bluuebunny/crossref_metadata_2025 huggingface dataset:
Effectiveness of Different Cellulose-Based Filtration Materials against Inhalation of SARS-CoV-2-Like Particles
Authors: Araújo Alyne R. de , Nunes Lívio C. C. , Oliveira Karla C. B. F. , Carvalho Maria G. F. M. , Cardoso Juliana C. , Severino Patricia , Soares Monica F. L. R. , Souto Eliana B. , Lima Gildário D.
Published: July 2021

The respiratory protection equipment (RPE) used by health professionals consists of an essential device to prevent infectious diseases, especially those caused by biological agents such as the coronavirus (SARS-CoV-2). The current epidemiological panorama is worrying, and the context of creation and production of the mask has emerged as an alternative to RPE to face the public health crisis worldwide. The aim of this work is to present a low-cost alternative as an FFP2-like filter for a reusable respirator face mask. This study presents the comparison of different cellulose-based filtering materials performed by retention testing, time saturation testing, aerosol penetration testing, nanoparticle (~140 nm) filtration testing, bacterial filtration efficiency (BFE), analysis of material morphology and usability. The reusable respirator face mask used in this study is an open-source innovation, using 3D printing. Cotton disc proved to be the best filter material for the reusable mask, with satisfactory results and a performance similar to that shown by the N95-type mask. The cotton disc ensured effectiveness over 6 h of use, and after that, the reusable respirator face mask (here, Delfi-TRON®) needed to be sanitized and replenished with a new cotton disc. Upon preliminary analyses of filtration efficiency, the selected filter was shown to be a low-cost biodegradable and biocompatible alternative.
Metabolically Unhealthy Phenotype: A Key Factor in Determining “Pediatric” Frailty
Authors: Calcaterra Valeria , Cena Hellas , Ruggieri Annamaria , Zuccotti Gianvincenzo , De Silvestri Annalisa , Bonalumi Gianni , Pelizzo Gloria
Published: July 2021

Frailty (FI) and metabolic syndrome (MS) are each associated with adverse health outcomes. A relationship between FI and MS has previously been described in adults. We considered the prevalence of a metabolically unhealthy phenotype (MUP) in malnourished children with neurological impairment and in subjects with obesity in comparison to a group of elderly individuals at risk of FI, and we did so in order to define the potential similarities that may underline the risk of FI in specific children. We considered 50 undernourished (defined as having a body mass index of BMI ≤ 2, standard deviation score, SDS, according to World Health Organization) disabled children; 50 children with obesity (BMI ≥ 2 SDS); 50 children who were a normal weight (−1 SDS ≤ BMI ≤ +1 SDS); 21 patients who were >75 years old. MUP was defined as the presence of at least one of the following risk factors: hypertension, hyperglycemia or diabetes, hypercholesterolemia, and hypertriglyceridemia. In children with a disability and obesity, a higher prevalence (p < 0.001) and risk (disability OR 54.88, obesity OR 13.37) of MUP was noted compared to children of a normal weight. Compared to elderly patients, the prevalence of MUP did not differ in disabled children. On the contrary, MUP was lower in children with obesity (p < 0.001) and in pediatric subjects of a normal weight (p < 0.01). MS might play a key role in “pediatric” frailty. The extremities of the aging process and malnutrition are likely key factors in the development of FI. A multidisciplinary approach to FI may represent an important milestone for pediatric care.
Sesquiterpene Lactones: Promising Natural Compounds to Fight Inflammation
Authors: Matos Melanie S. , Anastácio José D. , Nunes dos Santos Cláudia
Published: July 2021

Inflammation is a crucial and complex process that reestablishes the physiological state after a noxious stimulus. In pathological conditions the inflammatory state may persist, leading to chronic inflammation and causing tissue damage. Sesquiterpene lactones (SLs) are composed of a large and diverse group of highly bioactive plant secondary metabolites, characterized by a 15-carbon backbone structure. In recent years, the interest in SLs has risen due to their vast array of biological activities beneficial for human health. The anti-inflammatory potential of these compounds results from their ability to target and inhibit various key pro-inflammatory molecules enrolled in diverse inflammatory pathways, and prevent or reduce the inflammatory damage on tissues. Research on the anti-inflammatory mechanisms of SLs has thrived over the last years, and numerous compounds from diverse plants have been studied, using in silico, in vitro, and in vivo assays. Besides their anti-inflammatory potential, their cytotoxicity, structure–activity relationships, and pharmacokinetics have been investigated. This review aims to gather the most relevant results and insights concerning the anti-inflammatory potential of SL-rich extracts and pure SLs, focusing on their effects in different inflammatory pathways and on different molecular players.
The Influence of Selected Factors on the Aqueous Cryptotanshinone Solubility
Authors: Kobryń Justyna , Dałek Jowita , Musiał Witold
Published: July 2021

The application of cryptotanshinone (CT), a diterpenoid obtained from the root of Salviae miltiorrhiza, is significantly hindered due to its poor aqueous solubility. The aim of the present research was to develop an optimal solvent for analytical and preparative procedures of prospective dermal hydrogel formulations with CT. The influence of pH, temperature, and cosolvent presence on the solubility of CT was examined. Various components were applied to increase CT solubility, i.e., ethanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-(hydroxymethyl)-1,3-propanediol, 2,2′,2″-nitrilotriethanol, and triisopropanoloamine. The concentration of CT was analyzed by spectral and chromatographic methods, including UV–vis and HPLC methods. The increased solubility of CT was demonstrated in alkaline solvents with ethanol as a cosolvent. CT solutions doped with alcoholamines are more stable compared to CT solutions doped with NaOH.
Process Modeling and Simulation of Tableting—An Agent-Based Simulation Methodology for Direct Compression
Authors: Martin Niels Lasse , Schomberg Ann Kathrin , Finke Jan Henrik , Abraham Tim Gyung-min , Kwade Arno , Herrmann Christoph
Published: July 2021

In pharmaceutical manufacturing, the utmost aim is reliably producing high quality products. Simulation approaches allow virtual experiments of processes in the planning phase and the implementation of digital twins in operation. The industrial processing of active pharmaceutical ingredients (APIs) into tablets requires the combination of discrete and continuous sub-processes with complex interdependencies regarding the material structures and characteristics. The API and excipients are mixed, granulated if required, and subsequently tableted. Thereby, the structure as well as the properties of the intermediate and final product are influenced by the raw materials, the parametrized processes and environmental conditions, which are subject to certain fluctuations. In this study, for the first time, an agent-based simulation model is presented, which enables the prediction, tracking, and tracing of resulting structures and properties of the intermediates of an industrial tableting process. Therefore, the methodology for the identification and development of product and process agents in an agent-based simulation is shown. Implemented physical models describe the impact of process parameters on material structures. The tablet production with a pilot scale rotary press is experimentally characterized to provide calibration and validation data. Finally, the simulation results, predicting the final structures, are compared to the experimental data.
Antitumor Activity against Human Colorectal Adenocarcinoma of Silver Nanoparticles: Influence of [Ag]/[PVP] Ratio
Authors: Cruz-Ramírez Omar Ulises , Valenzuela-Salas Lucía Margarita , Blanco-Salazar Alberto , Rodríguez-Arenas José Antonio , Mier-Maldonado Paris A. , García-Ramos Juan Carlos , Bogdanchikova Nina , Pestryakov Alexey , Toledano-Magaña Yanis
Published: July 2021

Silver nanoparticles (AgNPs) not only have shown remarkable results as antimicrobial and antiviral agents but also as antitumor agents. This work reports the complete characterization of five polyvinylpyrrolidone-coated AgNP (PVP-AgNP) formulations, their cytotoxic activity against human colon tumor cells (HCT-15), their cytotoxic effect on primary mouse cultures, and their lethal dose on BALB/c mice. The evaluated AgNP formulations have a composition within the ranges Ag: 1.14–1.32% w/w, PVP: 19.6–24.5% and H2O: 74.2–79.2% with predominant spherical shape within an average size range of 16–30 nm according to transmission electron microscopy (TEM). All formulations assessed increase mitochondrial ROS concentration and induce apoptosis as the leading death pathway on HCT-15 cells. Except for AgNP1, the growth inhibition potency of AgNP formulations of human colon tumor cancer cells (HCT-15) is 34.5 times higher than carboplatin, one of the first-line chemotherapy agents. Nevertheless, 5–10% of necrotic events, even at the lower concentration evaluated, were observed. The cytotoxic selectivity was confirmed by evaluating the cytotoxic effect on aorta, spleen, heart, liver, and kidney primary cultures from BALB/c mice. Despite the cytotoxic effects observed in vitro, the lethal dose and histopathological analysis showed the low toxicity of these formulations (all of them on Category 4 of the Globally Harmonized System of Classification and Labelling of Chemicals) and minor damage observed on analyzed organs. The results provide an additional example of the rational design of safety nanomaterials with antitumor potency and urge further experiments to complete the preclinical studies for these AgNP formulations.
Two Experimental Devices for Record and Playback of Tactile Data
Authors: Ohka Masahiro , Komura Hiraku , Watanabe Keisuke , Nomura Ryota
Published: July 2021

A tactile record and playback system will progress tactileology—a new cross-disciplinary field related to tactile sensations—as it will enhance its use in the instruction, archiving, and analysis of human manipulation. In this paper, we describe two key devices for achieving tactileology: a tactile sensor capturing human tactile sense (fingernail color sensor) and a robotic tactile sensor, both of which can detect not only normal force but also tangential force. This is beneficial because people manipulate objects and tools in various ways, such as grasping, picking, and rubbing. The fingernail color sensor registers the three-dimensional (3D) force applied to a fingertip by detecting the fingernail color change caused by blood distribution under the fingernail, which can be observed with green illumination and a miniature camera. Since detecting this color change is more complicated than using a robotic sensor, the relationships between the image and 3D force are learned using a convolutional neural network (CNN). In the robotic sensor, the 3D force applied to a robotic finger transforms into a bright area using an illuminated acrylic core, a rubber robotic finger skin, and a miniature camera. We measure normal force and tangential force by the brightness and movement of the bright area, respectively. Using a force gauge or an electronic scale for measurement, we perform a series of evaluation experiments. The experimental results show that the precision of both the fingernail color sensor and the robotic tactile sensor are sufficient for our system.
Flammability Characteristics of Thermally Modified Meranti Wood Treated with Natural and Synthetic Fire Retardants
Authors: Gaff Milan , Čekovská Hana , Bouček Jiří , Kačíková Danica , Kubovský Ivan , Tribulová Tereza , Zhang Lingfeng , Marino Salvio , Kačík František
Published: July 2021

This paper deals with the effect of synthetic and natural flame retardants on flammability characteristics and chemical changes in thermally treated meranti wood (Shorea spp.). The basic chemical composition (extractives, lignin, holocellulose, cellulose, and hemicelluloses) was evaluated to clarify the relationships of temperature modifications (160 °C, 180 °C, and 210 °C) and incineration for 600 s. Weight loss, burning speed, the maximum burning rate, and the time to reach the maximum burning rate were evaluated. Relationships between flammable properties and chemical changes in thermally modified wood were evaluated with the Spearman correlation. The thermal modification did not confirm a positive contribution to the flammability and combustion properties of meranti wood. The effect of the synthetic retardant on all combustion properties was significantly higher compared to that of the natural retardant.
Wetting Simulations of High-Performance Polymer Resins on Carbon Surfaces as a Function of Temperature Using Molecular Dynamics
Authors: Bamane Swapnil S. , Gaikwad Prashik S. , Radue Matthew S. , Gowtham S. , Odegard Gregory M.
Published: July 2021

Resin/reinforcement wetting is a key parameter in the manufacturing of carbon nanotube (CNT)-based composite materials. Determining the contact angle between combinations of liquid resin and reinforcement surfaces is a common method for quantifying wettability. As experimental measurement of contact angle can be difficult when screening multiple high-performance resins with CNT materials such as CNT bundles or yarns, computational approaches are necessary to facilitate CNT composite material design. A molecular dynamics simulation method is developed to predict the contact angle of high-performance polymer resins on CNT surfaces dominated by aromatic carbon, aliphatic carbon, or a mixture thereof (amorphous carbon). Several resin systems are simulated and compared. The results indicate that the monomer chain length, chemical groups on the monomer, and simulation temperature have a significant impact on the predicted contact angle values on the CNT surface. Difunctional epoxy and cyanate ester resins show the overall highest levels of wettability, regardless of the aromatic/aliphatic nature of the CNT material surface. Tetrafunctional epoxy demonstrates excellent wettability on aliphatic-dominated surfaces at elevated temperatures. Bismaleimide and benzoxazine resins show intermediate levels of wetting, while typical molecular weights of polyether ether ketone demonstrate poor wetting on the CNT surfaces.
Durable Modification of Wood by Benzoylation—Proof of Covalent Bonding by Solution State NMR and DOSY NMR Quick-Test
Authors: Namyslo Jan C. , Drafz Martin H. H. , Kaufmann Dieter E.
Published: July 2021

A convenient, broadly applicable and durable wood protection was recently published by Kaufmann and Namyslo. This procedure efficiently allows for esterification of wood hydroxyl groups with (1H-benzotriazolyl)-activated functionalized benzoic acids. The result of such wood-modifying reactions is usually monitored by an increase in mass of the wood material (weight percent gain value, WPG) and by infrared spectroscopy (IR). However, diagnostic IR bands suffer from overlap with naturally occurring ester groups, mainly in the hemicellulose part of unmodified wood. In contrast to known NMR spectroscopy approaches that use the non-commonly available solid state techniques, herein we present solution state NMR proof of the covalent attachment of our organic precursors to wood. The finding is based on a time-efficient, non-uniformly sampled (NUS) solution state 1H,13C-HMBC experiment that only needs a tenth of the regular recording time. The appropriate NMR sample of thoroughly dissolved modified wood was prepared by a mild and non-destructive method. The 2D-HMBC shows a specific cross-signal caused by spin–spin coupling over three bonds from the ester carbonyl carbon atom to the α-protons of the esterified wood hydroxyl groups. This specific coupling pathway requires a covalent bonding as a conditio sine qua non. An even more rapid test to monitor the covalent bonding was achieved with an up-to-date diffusion-ordered spectroscopy sequence (Oneshot—DOSY) based on 1H or 19F as the sensitive nucleus. The control experiment in a series of DOSY spectra gave a by far higher D value of (1.22 ± 0.06)∙10−10 m2∙s−1, which is in accordance with fast diffusion of the “free” and thus rapidly moving small precursor molecule provided as its methyl ester. In the case of a covalent attachment to wood, a significantly smaller D value of (0.12 ± 0.01)∙10−10 m2∙s−1 was obtained.
New Photoresponsive Poly(meth)acrylates Bearing Azobenzene Moieties Obtained via ATRP Polymerization Exhibiting Liquid-Crystalline Behavior
Authors: Cieciórski Piotr , Majewski Paweł W. , Megiel Elżbieta
Published: July 2021

Here, we report our studies on photoresponsive poly(meth)acrylates containing azobenzene groups connected to a polymer backbone via a short methylene linker. A series of side-chain azobenzene polymers was synthesized via the atom transfer radical polymerization (ATRP) technique using several catalytic systems. The polymers synthesized under the optimized conditions were characterized by a narrow polydispersity (Đ ≤ 1.35), and they underwent a reversible transformation of their structure under light illumination. The fabricated polymers can store and release energy accumulated during the UV-light illumination by the thermal cis-trans isomerization of the chromophore groups. The enthalpy of the process (determined from DSC) was relatively high and equaled 61.9 J∙g−1 (17 Wh∙kg−1), indicating a high potential of these materials in energy storage applications. The liquid-crystalline behavior of the synthesized poly(meth)acrylates was demonstrated by the birefringent optical textures as observed in thin-films and X-ray scattering studies.
Analysis of PLA Composite Filaments Reinforced with Lignin and Polymerised-Lignin-Treated NFC
Authors: Gregor-Svetec Diana , Leskovšek Mirjam , Leskovar Blaž , Stanković Elesini Urška , Vrabič-Brodnjak Urška
Published: July 2021

Polylactic acid (PLA) is one of the most suitable materials for 3D printing. Blending with nanoparticles improves some of its properties, broadening its application possibilities. The article presents a study of composite PLA matrix filaments with added unmodified and lignin/polymerised lignin surface-modified nanofibrillated cellulose (NFC). The influence of untreated and surface-modified NFC on morphological, mechanical, technological, infrared spectroscopic, and dynamic mechanical properties was evaluated for different groups of samples. As determined by the stereo and scanning electron microscopy, the unmodified and surface-modified NFCs with lignin and polymerised lignin were present in the form of plate-shaped agglomerates. The addition of NFC slightly reduced the filaments’ tensile strength, stretchability, and ability to absorb energy, while in contrast, the initial modulus slightly improved. By adding NFC to the PLA matrix, the bending storage modulus (E’) decreased slightly at lower temperatures, especially in the PLA samples with 3 wt% and 5 wt% NFC. When NFC was modified with lignin and polymerised lignin, an increase in E’ was noticed, especially in the glassy state.
The Effects of Nanosilica on Mechanical Properties and Fracture Toughness of Geopolymer Cement
Authors: Rahmawati Cut , Aprilia Sri , Saidi Taufiq , Aulia Teuku Budi , Hadi Agung Efriyo
Published: July 2021

Nanosilica produced from physically-processed white rice husk ash agricultural waste can be incorporated into geopolymer cement-based materials to improve the mechanical and micro performance. This study aimed to investigate the effect of natural nanosilica on the mechanical properties and microstructure of geopolymer cement. It examined the mechanical behavior of geopolymer paste reinforced with 2, 3, and 4 wt% nanosilica. The tests of compressive strength, direct tensile strength, three bending tests, Scanning Electron Microscope-Energy Dispersive X-ray (SEM/EDX), X-ray Diffraction (XRD), and Fourier-transform Infrared Spectroscopy (FTIR) were undertaken to evaluate the effect of nanosilica addition to the geopolymer paste. The addition of 2 wt% nanosilica in the geopolymer paste increased the compressive strength by 22%, flexural strength by 82%, and fracture toughness by 82% but decreased the direct tensile strength by 31%. The microstructure analysis using SEM, XRD, and FTIR showed the formation of calcium alumina-silicate hydrate (C–A–S–H) gel. The SEM images also revealed a compact and cohesive geopolymer matrix, indicating that the mechanical properties of geopolymers with 2 wt% nanosilica were improved. Thus, it is feasible for nanosilica to be used as a binder.
Investigation on the Durability of E-Glass/Epoxy Composite Exposed to Seawater at Elevated Temperature
Authors: Idrisi Amir Hussain , Mourad Abdel-Hamid I. , Abdel-Magid Beckry M. , Shivamurty B.
Published: July 2021

In this manuscript, the durability of the E-glass/epoxy composite was determined under a seawater environment. The effect of harsh environment was investigated in terms of seawater absorption, microstructure and degradation in mechanical properties. E-glass epoxy composite specimens were conditioned in gulf seawater at 23 °C, 65 °C and 90 °C for the period of 12 months. It was observed that the mass of the samples increased after the immersion of 12 months at 23 °C and 65 °C whereas it reduced at 90 °C. The salt deposition was observed at the surface of specimens without any crack for the seawater conditioning at 23 °C and 65 °C. The swelling and crack formation were significantly visible on the surface of the specimen immersed for 12 months at 90 °C. It indicates that the degradation mechanism accelerated at elevated temperature results fiber/matrix debonding. The tensile test indicates slight variation in the elastic modulus and reduction in strength of E-glass epoxy composite by 1% and 9% for specimens immersed at 23 °C and 65 °C respectively. However, at 90 °C, the tensile strength sharply decreased to 7% and elastic modulus significantly increased in the exposure of 12 months. A prediction approach based on a time-shift factor (TSF) was used. This model predicted that the strength retention of E-glass/Epoxy composite will be reduced to 7% in 450 years after immersion in seawater at 23 °C. Lastly, the activation energy for the degradation of the composite was calculated.
Antimicrobial Polymeric Composites with Embedded Nanotextured Magnesium Oxide
Authors: Aničić Nemanja , Kurtjak Mario , Jeverica Samo , Suvorov Danilo , Vukomanović Marija
Published: July 2021

Nanotextured magnesium oxide (MgO) can exhibit both antibacterial and tissue regeneration activity, which makes it very useful for implant protection. To successfully combine these two properties, MgO needs to be processed within an appropriate carrier system that can keep MgO surface available for interactions with cells, slow down the conversion of MgO to the less active hydroxide and control MgO solubility. Here we present new composites with nanotextured MgO microrods embedded in different biodegradable polymer matrixes: poly-lactide-co-glycolide (PLGA), poly-lactide (PLA) and polycaprolactone (PCL). Relative to their hydrophilicity, polarity and degradability, the matrices were able to affect and control the structural and functional properties of the resulting composites in different manners. We found PLGA matrix the most effective in performing this task. The application of the nanotextured 1D morphology and the appropriate balancing of MgO/PLGA interphase interactions with optimal polymer degradation kinetics resulted in superior bactericidal activity of the composites against either planktonic E. coli or sessile S. epidermidis, S. aureus (multidrug resistant-MRSA) and three clinical strains isolated from implant-associated infections (S. aureus, E. coli and P. aeruginosa), while ensuring controllable release of magnesium ions and showing no harmful effects on red blood cells.
Effect of Femtosecond-Laser-Structured Injection Molding Tool on Mechanical Properties of the Manufactured Product
Authors: Kun Krisztián , Weltsch Zoltán
Published: July 2021

During the injection molding process, the melt travels with a flow due to friction. As the velocity of the layers next to the wall is less than that of those flowing in the middle of the channel, a fountain flow is formed at the melt front. The temperature of the polymer surface decreases from the melt temperature to the contact temperature after contacting the mold surface. Based on all this, a complex shell–core structure is formed in injection-molded products, which can be influenced by the processing parameters and the surface of the tool insert. This paper focuses on investigating the effect of the microstructures replicated from the insert to the polymer product on its mechanical properties. During the research, two microstructured surfaces were created, with different effects on the melt flow formed by the femtosecond laser. These were compared with a ground insert to analyze the effects. For examining the effect of technological variables on the mechanical properties, an experimental design was used. The structure created by the femtosecond laser on the surface of the tool influenced the mechanical properties of the polymer products. Recognizing the effect of microstructures on the melt front and, through this, the change in mechanical properties, a predefined polymer product property can be achieved.
Applied Rheology as Tool for the Assessment of Chitosan Hydrogels for Regenerative Medicine
Authors: Sánchez-Cid Pablo , Jiménez-Rosado Mercedes , Alonso-González María , Romero Alberto , Perez-Puyana Victor
Published: July 2021

The regeneration of soft tissues that connect, support or surround other tissues is of great interest. In this sense, hydrogels have great potential as scaffolds for their regeneration. Among the different raw materials, chitosan stands out for being highly biocompatible, which, together with its biodegradability and structure, makes it a great alternative for the manufacture of hydrogels. Therefore, the aim of this work was to develop and characterize chitosan hydrogels. To this end, the most important parameters of their processing, i.e., agitation time, pH, gelation temperature and concentration of the biopolymer used were rheologically evaluated. The results show that the agitation time does not have a significant influence on hydrogels, whereas a change in pH (from 3.2 to 7) is a key factor for their formation. Furthermore, a low gelation temperature (4 °C) favors the formation of the hydrogel, showing better mechanical properties. Finally, there is a percentage of biopolymer saturation, from which the properties of the hydrogels are not further improved (1.5 wt.%). This work addresses the development of hydrogels with high thermal resistance, which allows their use as scaffolds without damaging their mechanical properties.
Thermally Conductive Shape Memory Polymer Composites Filled with Boron Nitride for Heat Management in Electrical Insulation
Authors: Rybak Andrzej , Malinowski Lukasz , Adamus-Wlodarczyk Agnieszka , Ulanski Piotr
Published: July 2021

The evaluation of a possible application of functional shrinkable materials in thermally conductive electrical insulation elements was investigated. The effectiveness of an electron beam and gamma radiation on the crosslinking of a selected high density polyethylene grade was analyzed, both qualitatively and quantitatively. The crosslinked polymer composites filled with ceramic particles were successfully fabricated and tested. On the basis of the performed investigation, it was concluded that the selected filler, namely a boron nitride powder, is suitable for the preparation of the crosslinked polymer composites with enhanced thermal conductivity. The shape memory effect was fully observed in the crosslinked samples with a recovery factor reaching nearly 99%. There was no significant influence of the crosslinking, stretching, and recovery of the polymer composite during shape memory phenomenon on the value of thermal conductivity. The proposed boron nitride filled polyethylene composite subjected to crosslinking is a promising candidate for fabrication of thermally shrinkable material with enhanced heat dissipation functionality for application as electrically insulating components.
Multicore Assemblies from Three-Component Linear Homo-Copolymer Systems: A Coarse-Grained Modeling Study
Authors: Javan Nikkhah Sousa , Turunen Elsi , Lepo Anneli , Ala-Nissila Tapio , Sammalkorpi Maria
Published: July 2021

Multicore polymer micelles and aggregates are assemblies that contain several cores. The dual-length-scale compartmentalized solvophobic–solvophilic molecular environment makes them useful for, e.g., advanced drug delivery, high-precision synthesis platforms, confined catalysis, and sensor device applications. However, designing and regulating polymer systems that self-assemble to such morphologies remains a challenge. Using dissipative particle dynamics (DPD) simulations, we demonstrate how simple, three-component linear polymer systems consisting of free solvophilic and solvophobic homopolymers, and di-block copolymers, can self-assemble in solution to form well-defined multicore assemblies. We examine the polymer property range over which multicore assemblies can be expected and how the assemblies can be tuned both in terms of their morphology and structure. For a fixed degree of polymerization, a certain level of hydrophobicity is required for the solvophobic component to lead to formation of multicore assemblies. Additionally, the transition from single-core to multicore requires a relatively high solvophobicity difference between the solvophilic and solvophobic polymer components. Furthermore, if the solvophilic polymer is replaced by a solvophobic species, well-defined multicore–multicompartment aggregates can be obtained. The findings provide guidelines for multicore assemblies’ formation from simple three-component systems and how to control polymer particle morphology and structure.
Stress Distribution and Fracture Toughness of Underground Reinforced Plastic Pipe Composite
Authors: Abdellah Mohammed Y. , Alfattani Rami , Alnaser Ibrahim A. , Abdel-Jaber G. T.
Published: July 2021

Reinforced composite materials have many applications in the aerospace, marine, and petroleum industries. Glass fiber-reinforced pipes are of considerable importance as pressurized vessels, infrastructure materials, and petroleum wastewater pipelines. The stress intensity factor due to through-thickness discontinuities is a major parameter in fracture mechanics to understand the failure mechanisms in glass fiber-composite pipes. The stress intensity factor is calculated for a composite cylinder subjected to internal pressure using the linear extended finite element method based on the law of energy release evaluation of surface damage. The analytical model needs two material properties; they are the tensile strength and the fracture toughness; therefore, a standard tensile test was carried out on a standard specimen taken from the pipe’s wall thickness. Moreover, the compact tension test specimen was manufactured from the pipe’s wall thickness to obtain the fracture toughness. The average tensile strength was measured as 21.5 MPa with a standard deviation of 5.59 MPa, moreover, the average Young’s modulus was measured as 32.75 GPa with a standard deviation of 6.64 GPa. The fracture toughness was measured as 2322 (MPa m) with a standard deviation of 142.5 (MPa m), whereas the average surface release energy (GIC) was 153.6 kJ/m2 with a standard deviation of 22.53 kJ/m2. A valuable design equation was extracted from the finite element model to measure the effect of cracks on the hoop stress of the cylinder wall thickness based on a nonlinear model. Moreover, an acceptable equation was used to calculate the correction and shape factor of a cylinder with movable and unmovable through-thickness cracks. This study provides useful tools and guidance for the design and analysis of composite cylinders.
Auto-Disinfectant Acrylic Paints Functionalised with Triclosan and Isoborneol—Antibacterial Assessment
Authors: Machado Querido Micaela , Paulo Ivo , Hariharakrishnan Sriram , Rocha Daniel , Pereira Cristiana Costa , Barbosa Nuno , Bordado João Moura , Teixeira João Paulo , Galhano dos Santos Rui
Published: July 2021

Environmental surface contamination with microorganisms is a serious concern worldwide. Triclosan and isoborneol present good antimicrobial activity. Their immobilisation to paint substrates allows for development of a material that stays effective over a longer time. In this work, we disclosed the preliminary studies to evaluate the antimicrobial activity of the active molecule after being functionalised with isocyanates for further immobilisation on the paint substrate. Overall, the newly developed non-release antimicrobial coating provides an effective way of preventing the spread of diseases and has been proven to inhibit bacterial growth and with a considerable antimicrobial activity towards S. aureus, E. coli, and K. variicola at the tested concentrations.
A Molecular Simulation Study of Silica/Polysulfone Mixed Matrix Membrane for Mixed Gas Separation
Authors: Asif Khadija , Lock Serene Sow Mun , Taqvi Syed Ali Ammar , Jusoh Norwahyu , Yiin Chung Loong , Chin Bridgid Lai Fui , Loy Adrian Chun Minh
Published: July 2021

Polysulfone-based mixed matrix membranes (MMMs) incorporated with silica nanoparticles are a new generation material under ongoing research and development for gas separation. However, the attributes of a better-performing MMM cannot be precisely studied under experimental conditions. Thus, it requires an atomistic scale study to elucidate the separation performance of silica/polysulfone MMMs. As most of the research work and empirical models for gas transport properties have been limited to pure gas, a computational framework for molecular simulation is required to study the mixed gas transport properties in silica/polysulfone MMMs to reflect real membrane separation. In this work, Monte Carlo (MC) and molecular dynamics (MD) simulations were employed to study the solubility and diffusivity of CO2/CH4 with varying gas concentrations (i.e., 30% CO2/CH4, 50% CO2/CH4, and 70% CO2/CH4) and silica content (i.e., 15–30 wt.%). The accuracy of the simulated structures was validated with published literature, followed by the study of the gas transport properties at 308.15 K and 1 atm. Simulation results concluded an increase in the free volume with an increasing weight percentage of silica. It was also found that pure gas consistently exhibited higher gas transport properties when compared to mixed gas conditions. The results also showed a competitive gas transport performance for mixed gases, which is more apparent when CO2 increases. In this context, an increment in the permeation was observed for mixed gas with increasing gas concentrations (i.e., 70% CO2/CH4 > 50% CO2/CH4 > 30% CO2/CH4). The diffusivity, solubility, and permeability of the mixed gases were consistently increasing until 25 wt.%, followed by a decrease for 30 wt.% of silica. An empirical model based on a parallel resistance approach was developed by incorporating mathematical formulations for solubility and permeability. The model results were compared with simulation results to quantify the effect of mixed gas transport, which showed an 18% and 15% percentage error for the permeability and solubility, respectively, in comparison to the simulation data. This study provides a basis for future understanding of MMMs using molecular simulations and modeling techniques for mixed gas conditions that demonstrate real membrane separation.
Special Issue on “CFD Based Researches and Applications for Fluid Machinery and Fluid Device”
Authors: Kim Jin-Hyuk , Kim Sung-Min , Choi Minsuk , Tan Lei , Huang Bin , Pei Ji
Published: July 2021

The demand for computational fluid dynamics (CFD)-based numerical techniques is increasing rapidly with the development of the computing power system [...]
Study on Electrostatic Preparation High-Ash Coal from China Using Roll-Type Electrostatic Separator and the Combustion Characteristics of the Cleaned Coal
Authors: Liu Chengyuan , Wang Qingyue
Published: July 2021

The dry roll-type electrostatic coal beneficiation technology under high voltage is used to study the beneficiation of low-grade and high-ash coal in Inner Mongolia, northern China. The optimal coal beneficiation conditions are determined by adjusting three parameters: the electrode voltage, the distance between the electrode and the drum, and the angle θ of the electrode. The best quality clean coal is obtained under the condition of voltage of 30 kV, angle θ of 75°, and electrode distance of 7 cm. Moreover, after separation, the quality of clean coal accounted for 48.41% of the raw coal mass, while the ash ratio decreased from 38.6% of the raw coal to 18.71% of the clean coal, which significantly improves the coal usability. Finally, through the methods of combustion characteristics analysis, infrared spectrum analysis, and combustion exhaust gas analysis of raw and clean coal, it is proven that the roll-type electrostatic separation technology has a high coal beneficiation effect on the high-ash, low-grade coal in Inner Mongolia.
Carob Pulp: A Nutritional and Functional By-Product Worldwide Spread in the Formulation of Different Food Products and Beverages. A Review
Authors: Rodríguez-Solana Raquel , Romano Anabela , Moreno-Rojas José Manuel
Published: July 2021

Carob (Ceratonia siliqua L.) pod is a characteristic fruit from the Mediterranean regions. It is composed by seeds, the valuable part due to the extraction of locust bean gum, and the pulp, considered a by-product of the fruit processing industry. Carob pulp is a mixture of macro- and micronutrients, such as carbohydrates, vitamins and minerals, and secondary metabolites with functional properties. In the last few years, numerous studies on the chemical and biological characteristics of the pulp have been performed to encourage its commercial use. Its potential applications as a nutraceutical ingredient in many recipes for food and beverage elaborations have been extensively evaluated. Another aspect highlighted in this work is the use of alternative processes or conditions to mitigate furanic production, recognized for its toxicity. Furthermore, carob pulp’s similar sensorial, chemical and biological properties to cocoa, the absence of the stimulating alkaloids theobromine and caffeine, as well as its low-fat content, make it a healthier potential substitute for cocoa. This paper reviews the nutritional and functional values of carob pulp-based products in order to provide information on the proclaimed health-promoting properties of this interesting by-product.
Research on Prediction Accuracy of Coal Mine Gas Emission Based on Grey Prediction Model
Authors: Zeng Jun , Li Qinsheng
Published: July 2021

In order to achieve the accuracy of gas emission prediction for different workplaces in coal mines, three coal mining workings and four intake and return air roadway of working face in Nantun coal mine were selected for the study. A prediction model of gas emission volume based on the grey prediction model GM (1,1) was established. By comparing the predicted and actual values of gas emission rate at different working face locations, the prediction error of the gray prediction model was calculated, and the applicability and accuracy of the gray prediction method in the prediction of gas gushing out from working faces in coal mines were determined. The results show that the maximum error between the predicted and actual measured values of the gray model is 2.41%, and the minimum value is only 0.07%. There is no significant prediction error over a larger time scale; the overall prediction accuracy is high. It achieves the purpose of accurately predicting the amount of gas gushing from the working face within a short period of time. Consequently, the grey prediction model is of great significance in ensuring the safety production of coal mine working face and promote the safety management of coal mine.
Preparation of K Modified Three-Dimensionally Ordered Macroporous MnCeOx/Ti0.7Si0.3O2 Catalysts and Their Catalytic Performance for Soot Combustion
Authors: Zhang Chunlei , Yu Di , Peng Chao , Wang Lanyi , Fan Xiaoqiang , Yu Xuehua , Zhao Zhen
Published: July 2021

Soot particles in diesel engine exhaust is one of the main reasons for hazy weather and elimination of them is urgent for environmental protection. At present, it is still a challenge to develop new catalysts with high efficiency and low cost. In this paper, a kind of K modified three-dimensionally ordered macroporous (3DOM) MnCeOx/Ti0.7Si0.3O2 catalysts are designed and synthesized by a sample method. Due to the macroporous structure and synergistic effect of K, Mn, and Ce, the KnMnCeOx/Ti0.7Si0.3O2 (KnMnCeOx/M-TSO) catalysts exhibit good catalytic performance for soot combustion. The catalytic activity of K0.5MnCeOx/M-TSO was the best, and the T10, T50, and T90 are 287, 336, and 367 °C, respectively. After the prepared catalyst was doped with K, the physicochemical properties and catalytic performance changed significantly. In addition, the K0.5MnCeOx/M-TSO catalyst also somewhat exhibits sulfur tolerance owing to it containing Ti. Because of its simple synthesis, high activity, and low cost, the prepared KnMnCeOx/M-TSO catalysts are regarded as a promising candidate for application.
India’s Other Religious Freedom Problems
Authors: Shah Timothy S.
Published: July 2021

There is no doubt that India is far from perfect when it comes to religious freedom. Indeed, India’s religious freedom problems have become an increasing focus of scholarly and policy attention. However, almost all of this attention is directed at one particular subset of religious freedom problems—i.e., restrictions imposed on the religious freedom of India’s minority communities, and particularly Muslims and Christians. Meanwhile, serious religious freedom challenges experienced by members of India’s Hindu majority population tend to be ignored. In this article: (1) I first describe the religious freedom situation in India as a complex terrain that requires a multi-dimensional mapping. (2) I then survey existing, influential studies of the religious freedom situation in India and identify their tendency to generate flat, one-dimensional mappings, and their consequent failure to analyze restrictions on the religious freedom of India’s Hindus, including both Hindu individuals and institutions. (3) I briefly analyze India’s regime of “Hindu Erastianism”—i.e., its extensive system of state regulation and control of Hindu institutions—and suggest how and why this regime amounts to a direct attack on core features of institutional religious freedom. (4) I conclude by briefly suggesting that the whole range of India’s religious freedom problems—including its “other”, less discussed problems—can be traced to a longstanding and destructive pattern of ideological polarization that owes as much to an uncompromising statist secularism as to Hindu nationalism. The existence of this now deeply ingrained pattern bodes ill for improvements in India’s religious freedom situation in the short term, and suggests that it is the country’s public culture, rather than its political balance of power, that must change if the world’s largest democracy is to enjoy greater religious freedom and tolerance in the future.
Application of M5 Model Tree in Passive Remote Sensing of Thin Ice Cloud Microphysical Properties in Terahertz Region
Authors: Dong Pingyi , Liu Lei , Li Shulei , Hu Shuai , Bu Lingbing
Published: July 2021

This article presents a new method for retrieving the Ice Water Path (IWP), the median volume equivalent sphere diameter (Dme) of thin ice clouds (IWP < 100 g/m2, Dme < 80 μm) in the Terahertz band. The upwelling brightness temperature depressions caused by the ice clouds at 325.15, 448.0, 664.0 and 874.0 GHz channels are simulated by the Atmospheric Radiative Transfer Simulator (ARTS). The simulated forward radiative transfer models are taken as historical data for the M5 model tree algorithm to construct a set of piecewise functions which represent the relation of simulated brightness temperature depressions and IWP. The inversion results are optimized by an empirical relation of the IWP and the Dme for thin ice clouds which is summarized by previous studies. We inverse IWP and Dme with the simulated brightness temperature and analyze the inversion performance of selected channels. The 874.4 ± 6.0 GHz channel provides the most accurate results, because of the strong brightness temperature response to the change of IWP in the forward radiative transfer model. In order to improve the thin ice clouds IWP and Dme retrieval accuracy at the middle-high frequency channels in Terahertz band, a dual-channel inversion method was proposed that combines the 448.0± 3.0 GHz and 664.0 ± 4.2 GHz channel. The error analysis shows that the results of the 874.4 ± 6.0 GHz channel and the dual-channel inversion are reliable, and the IWP inversion results meet the error requirement range proposed by previous studies.
Monitoring Changes in the Transparency of the Largest Reservoir in Eastern China in the Past Decade, 2013–2020
Authors: Li Teng , Zhu Bozhong , Cao Fei , Sun Hao , He Xianqiang , Liu Mingliang , Gong Fang , Bai Yan
Published: July 2021

Based on characteristics analysis about remote sensing reflectance, the Secchi Disk Depth (SDD) in the Qiandao Lake was predicted from the Landsat8/OLI data, and its changing rates on a pixel-by-pixel scale were obtained from satellite remote sensing for the first time. Using 114 matchups data pairs during 2013–2019, the SDD satellite algorithms suitable for the Qiandao Lake were obtained through both the linear regression and machine learning (Support Vector Machine) methods, with remote sensing reflectance (Rrs) at different OLI bands and the ratio of Rrs (Band3) to Rrs (Band2) as model input parameters. Compared with field observations, the mean absolute relative difference and root mean squared error of satellite-derived SDD were within 20% and 1.3 m, respectively. Satellite-derived results revealed that SDD in the Qiandao Lake was high in boreal spring and winter, and reached the lowest in boreal summer, with the annual mean value of about 5 m. Spatially, high SDD was mainly concentrated in the southeast lake area (up to 13 m) close to the dam. The edge and runoff area of the lake were less transparent, with an SDD of less than 4 m. In the past decade (2013–2020), 5.32% of Qiandao Lake witnessed significant (p < 0.05) transparency change: 4.42% raised with a rate of about 0.11 m/year and 0.9% varied with a rate of about −0.09 m/year. Besides, the findings presented here suggested that heavy rainfall would have a continuous impact on the Qiandao Lake SDD. Our research could promote the applications of land observation satellites (such as the Landsat series) in water environment monitoring in inland reservoirs.