Influence of the interfacial reaction on interfacial adhesion in polyarylacetylene resin–silica glass composites

The influence of interfacial reaction on interfacial adhesion in silica glass/polyarylacetylene resin composites was studied. In order to achieve chemical reaction at the interface, vinyltrimethoxysilane was grafted onto silica glass surface to react with polyarylacetylene resin. The reaction between polyarylacetylene resin and vinyltrimethoxysilane was proved based on the model reaction between phenylacetylene and vinyltrimethoxysilane. At the same time, the modified silica glass surface characteristics were evaluated by contact-angle measurements and surface energy determination. The interfacial adhesion in silica glass/polyarylacetylene resin composites was evaluated by shear strength testing and fracture morphology analysis. It was concluded that polyarylacetylene resin reacted with vinyltrimethoxysilane. Furthermore, due to the reaction between polyarylacetylene resin and vinyltrimethoxysilane at the interface, the interfacial adhesion in composites was significantly increased. The improvement in interfacial adhesion was solely attributed to the interfacial reaction.     

Experimental solid–liquid equilibria and solid formation kinetics for carbon dioxide in methane for LNG processing

In cryogenic liquefaction processes, CO₂ poses a solid-formation risk even in trace concentrations. We present solid–fluid equilibrium (SFE) data for CO₂ in liquid methane at CO₂ concentrations from (52 to 500) ppm, extending the available data and indicating that models tuned to existing data over predict the solubility of CO₂ at LNG storage temperatures (~112 K) by nearly a factor of 3. The new data are used to improve the SFE model in the ThermoFAST software package. The formation kinetics of CO₂ solids in liquid methane are elucidated at conditions relevant to cryogenic gas processing. Repeated, ramped-temperature formation measurements provide a statistical basis for quantifying solidification risk. Nucleation rates extracted from the ramped-temperature data, consistent with those measured at fixed temperature, were used to extract parameters describing CO₂ solid formation in methane. These results significantly improve the ability to predict CO₂ solid formation risk in cryogenic natural gas processing.     

Potential Roles of Selectins in Periodontal Diseases and Associated Systemic Diseases: Could They Be Targets for Immunotherapy?

Periodontal diseases are predisposing factors to the development of many systemic disorders, which is often initiated via leukocyte infiltration and vascular inflammation. These diseases could significantly affect human health and quality of life. Hence, it is vital to explore effective therapies to prevent disease progression. Periodontitis, which is characterized by gingival bleeding, disruption of the gingival capillary’s integrity, and irreversible destruction of the periodontal supporting bone, appears to be caused by overexpression of selectins in periodontal tissues. Selectins (P-, L-, and E-selectins) are vital members of adhesion molecules regulating inflammatory and immune responses. They are mainly located in platelets, leukocytes, and endothelial cells. Furthermore, selectins are involved in the immunopathogenesis of vascular inflammatory diseases, such as cardiovascular disease, diabetes, cancers, and so on, by mediating leukocyte recruitment, platelet activation, and alteration of endothelial barrier permeability. Therefore, selectins could be new immunotherapeutic targets for periodontal disorders and their associated systemic diseases since they play a crucial role in immune regulation and endothelium dysfunction. However, the research on selectins and their association with periodontal and systemic diseases remains limited. This review aims to discuss the critical roles of selectins in periodontitis and associated systemic disorders and highlights the potential of selectins as therapeutic targets.     

Could Lower Testosterone in Older Men Explain Higher COVID-19 Morbidity and Mortalities?

The health scourge imposed on humanity by the COVID-19 pandemic seems not to recede. This fact warrants refined and novel ideas analyzing different aspects of the illness. One such aspect is related to the observation that most COVID-19 casualties were older males, a tendency also noticed in the epidemics of SARS-CoV in 2003 and the Middle East respiratory syndrome in 2012. This gender-related difference in the COVID-19 death toll might be directly involved with testosterone (TEST) and its plasmatic concentration in men. TEST has been demonstrated to provide men with anti-inflammatory and immunological advantages. As the plasmatic concentration of this androgen decreases with age, the health benefit it confers also diminishes. Low plasmatic levels of TEST can be determinant in the infection’s outcome and might be related to a dysfunctional cell Ca²⁺ homeostasis. Not only does TEST modulate the activity of diverse proteins that regulate cellular calcium concentrations, but these proteins have also been proven to be necessary for the replication of many viruses. Therefore, we discuss herein how TEST regulates different Ca²⁺-handling proteins in healthy tissues and propose how low TEST concentrations might facilitate the replication of the SARS-CoV-2 virus through the lack of modulation of the mechanisms that regulate intracellular Ca²⁺ concentrations.     

Development and verification of coarse-grain CFD-DEM for nonspherical particles in a gas–solid fluidized bed

Computational fluid dynamics coupled with discrete element method (CFD-DEM) has been widely used to understand the complicated fundamentals inside gas–solid fluidized beds. To realize large-scale simulations, CFD-DEM integrated with coarse-grain model (CG CFD-DEM) provides a feasible solution, and has led to a recent upsurge of interest. However, when dealing with large-scale simulations involving irregular-shaped particles such as biomass particles featuring elongated shapes, current CG models cannot function as normal because they are all developed for spherical particles. To address this issue, a CG CFD-DEM for nonspherical particles is proposed in this study, and the morphology of particles is characterized by the super-ellipsoid model. The effectiveness and accuracy of CG CFD-DEM for nonspherical particles are comprehensively evaluated by comparing the hydrodynamic behaviors with the results predicted by traditional CFD-DEM in a gas–solid fluidized bed. It is demonstrated that the proposed model can accurately model gas–solid flow containing nonspherical particles, merely the particle dynamics are somewhat lost due to the scaleup of particle size. Finally, the calculation efficiency of CG CFD-DEM is assessed, and the results show that CG CFD-DEM can largely reduce computational costs mainly by improving the calculation efficiency of DEM. In general, the proposed CG CFD-DEM for nonspherical particles strikes a good balance between efficiency and accuracy, and has shown its prospect as a high-efficiency alternative to traditional CFD-DEM for engineering applications involving nonspherical particles.     

Small amorphous and crystalline Ni–P particles synthesized in glycol for catalytic hydrogenation of nitrobenzene

Amorphous and crystalline Ni–P particles were synthesized via atmospheric solvothermal method using the cheap materials of nickel chloride hexahydrate and sodium hypophosphite. The Ni–P samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Uniform and small Ni–P particle sizes were obtained at facile conditions, and the phase state of Ni–P could be controlled conveniently by adjusting the synthetic time. In the hydrogenation of nitrobenzene, the amorphous Ni–P gave much higher activities compared to the counterpart crystalline Ni–P.     

Could the Epigenetics of Eosinophils in Asthma and Allergy Solve Parts of the Puzzle?

Epigenetics is a field of study investigating changes in gene expression that do not alter the DNA sequence. These changes are often influenced by environmental or social factors and are reversible. Epigenetic mechanisms include DNA methylation, histone modification, and noncoding RNA. Understanding the role of these epigenetic mechanisms in human diseases provides useful information with regard to disease severity and development. Several studies have searched for the epigenetic mechanisms that regulate allergies and asthma; however, only few studies have used samples of eosinophil, a proinflammatory cell type known to be largely recruited during allergic or asthmatic inflammation. Such studies would enable us to better understand the factors that influence the massive recruitment of eosinophils during allergic and asthmatic symptoms. In this review, we sought to summarize different studies that aimed to discover differential patterns of histone modifications, DNA methylation, and noncoding RNAs in eosinophil samples of individuals with certain diseases, with a particular focus on those with asthma or allergic diseases.     

Practical suggestions for meeting USEPA compliance monitoring requirements and in‐plant operational control of chlorine dioxide in drinking water.

An overview of current US Environmental Protection Agency (EPA) compliance objectives in the use and control of chlorine dioxide (ClO₂) in public drinking water treatment will be presented. Although these objectives were proposed in the 1994 Disinfectants/Disinfection Byproducts Rule (D/DBP), simple modifications to the frequency and approved list of analytical methods in the final Rule will greatly enhance public health protection afforded by operators at water treatment plants.

Ongoing concerns of acute health risks are associated with overexposure to ClO₂ or its principal DBP, the chlorite ion. Water leaving the plant needs to be monitored for both compounds on a daily basis using either approved or newly‐devised, more accurate methods such as Lissamine Green B. Monthly determinations for chlorite and chlorate ion species, using approved ion chromatography (EPA method 300.0 or 300.1), must also be carried out on samples from 3 locations in the distribution system. Lack of control of the generation process can influence purity of the ClO₂, possibly leading to elevated levels of undesirable byproducts associated with its use. Notable organoleptic episodes of peculiar and unusually obnoxious character may result from such high levels in finished waters. Specific examples of simplified testing methods and suggestions for operator and process control are outlined. Operational steps may be taken that ensure accurate ClO₂ feed control, equipment reliability and simple assessment of finished water for residual oxidants. Such operator‐based practices can be easily established on a day‐to‐day basis. These practices compliment the recent USEPA D/DBP Stage 1 final compliance monitoring schedules, provide adequate in‐plant operator control of chemical feed, and can lead to avoidance of severe public notification required by USEPA in the event of non‐compliance.     

Fluidization of elongated particles—Effect of multi-particle correlations for drag,lift, and torque in CFD-DEM

Having proper correlations for hydrodynamic forces is essential for successful CFD-DEM simulations of a fluidized bed. For spherical particles in a fluidized bed, efficient correlations for predicting the drag force, including the crowding effect caused by surrounding particles, are already available and well tested. However, for elongated particles, next to the drag force, the lift force, and hydrodynamic torque also gain importance. In this work, we apply recently developed multi-particle correlations for drag, lift and torque in CFD-DEM simulations of a fluidized bed with spherocylindrical particles of aspect ratio 4 and compare them to simulations with widely used single-particle correlations for elongated particles. Simulation results are compared with previous magnetic particle tracking experimental results. We show that multi-particle correlations improve the prediction of particle orientation and vertical velocity. We also show the importance of including hydrodynamic torque.     

Syngas methanation for substitute natural gas over Ni–Mg/Al2O3 catalyst in fixed and fluidized bed reactors

A comparative study was conducted for laboratory syngas methanation over a self-made Ni–Mg/Al₂O₃ catalyst to demonstrate the technical advantages of fluidized bed over fixed bed reactor. At different reaction temperatures, gas velocities and pressures, the CO conversion and selectivity to CH₄ in fluidized bed were shown to be higher than in fixed bed, and much closer to the thermodynamic equilibriums. The spent catalysts from fluidized bed methanation had distinctively low and easy-oxidizing deposited carbon in comparison with that from fixed bed. The results were attributed to the bigger effective catalytic surface, better heat and mass transfer in fluidized bed reactor.     

Aluminum- and calcium-incorporated MCM-41-type silica as supports for the immobilization of titanium(IV) isopropoxide in ring-opening polymerization of l-lactide and ε-caprolactone

Aluminum- and calcium-incorporated MCM-41-type silica with various Al/Si and Ca/Si ratios were evaluated as catalytic supports for ring-opening polymerization (ROP) of l-lactide and ε-caprolactone. The catalytic centers were generated by grafting titanium(IV) isopropoxide onto the support. All prepared heterogeneous catalysts better restrained the ROP of lactide than the homogeneous analog, titanium(IV) isopropoxide. Compared to siliceous MCM-41, the incorporation of aluminum or calcium in MCM-41 framework improved the molecular weight of the polymers although it lessened the polymerization rate. The more acidic Al-MCM-41 support appeared to be more favorable than the more basic Ca-MCM-41 support for the ROP reactions.     

Crack formation,exfoliation, and ridge formation in 500 °C annealed sol–gel silica coatings on stainless steel SUS304: Part II Spectroscopic and mechanical analyses and insights into mechanisms controlling coating characteristics

This report is a continuation of Part I of my studies of a non-aqueous sol–gel silica coating deposited on stainless steel SUS304. Part I discussed the microscopic observation of cracks, ridges and interlayers within the resulting silica coatings, and provided limited insight into their respective mechanisms of formation. This report provides further explanation for the mechanisms of these processes, as evidenced by spectroscopic and nano-indentation analyses of the coatings. Specifically, the coatings were analyzed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Auger electron spectroscopy. These results are discussed along with those obtained in Part I to further assess the mechanisms of crack formation in the coatings, and it was found that coating shrinkage and tension most likely caused crack formation. It seems that the O-deficient interlayers were formed under a mild oxidation condition existed around the silica/SUS304 interface during ～500 °C annealing. Additionally, nano-indentation analysis indicated that the coatings were compact, but the coatings’ hardness was intermediate. Suggestions for improvement of sol–gel silica coatings on stainless steel are also provided.     

Is There a Role for Immunoregulatory and Antiviral Oligonucleotides Acting in the Extracellular Space? A Review and Hypothesis

Here, we link approved and emerging nucleic acid-based therapies with the expanding universe of small non-coding RNAs (sncRNAs) and the innate immune responses that sense oligonucleotides taken up into endosomes. The Toll-like receptors (TLRs) 3, 7, 8, and 9 are located in endosomes and can detect nucleic acids taken up through endocytic routes. These receptors are key triggers in the defense against viruses and/or bacterial infections, yet they also constitute an Achilles heel towards the discrimination between self- and pathogenic nucleic acids. The compartmentalization of nucleic acids and the activity of nucleases are key components in avoiding autoimmune reactions against nucleic acids, but we still lack knowledge on the plethora of nucleic acids that might be released into the extracellular space upon infections, inflammation, and other stress responses involving increased cell death. We review recent findings that a set of single-stranded oligonucleotides (length of 25–40 nucleotides (nt)) can temporarily block ligands destined for endosomes expressing TLRs in human monocyte-derived dendritic cells. We discuss knowledge gaps and highlight the existence of a pool of RNA with an approximate length of 30–40 nt that may still have unappreciated regulatory functions in physiology and in the defense against viruses as gatekeepers of endosomal uptake through certain routes.     

Membrane distillation and pervaporation for ethanol removal: are we comparing in the right way?

A new glance on the comparison between membrane distillation (MD) and pervaporation is performed. There is a difficulty in this comparison, mainly due to different hydrodynamic conditions reported in the literature. Pervaporation and MD are similar although the comparison between these two processes can be tricky. In that way, how can we make a proper comparison between results of these two processes? This study proposes a reasonable comparison between MD and pervaporation for ethanol–water separation. Two very distinct regions of results in terms of selectivity and flux are presented. Feed temperature and composition and concentration polarization effects were also investigated.     

Fine particles sampled at an urban background site and an industrialized coastal site in Northern France—Part 2: Comparison of offline and online analyses for carbonaceous aerosols

Particulate matter was sampled in Northern France during two summer and winter periods at both an urban background site (Douai, DO) and an industrialized coastal site (Grande-Synthe, GS). Ambient levels of particulate carbonaceous species and Polycyclic Aromatic Hydrocarbons (PAH) were measured by real-time measurements and via collection and analysis of offline filters (F). The comparison between online organic matter (OM) measured by an Aerosol Mass Spectrometer (AMS) and organic carbon (OC) determined by an offline thermal-optical method showed good linear trends in wintertime GS (r² = 0.82 while only 0.50 in summer), and DO (r² = 0.86 in summer and 0.92 in winter). However, significant differences were observed between analytical methods and sites with OC_AMS/OC_F ratios decreasing from 0.80 in DO during winter to ≈0.20 for GS in summer, suggesting that a large part of OM could be in the PM₁–PM_2.5 fraction. The simultaneous measurements of Black Carbon (BC) and Elemental Carbon (EC) concentrations in PM_2.5 were also well correlated at both sites with r² = 0.61–0.97 and slopes between 0.6 and 0.8. PAHs were analyzed in PM_2.5 and also measured online by AMS in PM₁. Their wintertime concentrations were highly correlated in DO (r² = 0.98) and to a lesser degree in GS (r² = 0.67). r² values determined for comparison between online and offline parameters (OC and PAHs) in GS were lower than in DO, probably due to a more complex aerosol composition and a higher variability of the physical and chemical properties resulting from the coastal situation and diversity of emission sources in the vicinity of GS.

Copyright © 2018 American Association for Aerosol Research     

New approach for simultaneous enhancement of anticorrosive and mechanical properties of coatings: Application of water repellent nano CaCO3–PANI emulsion nanocomposite in alkyd resin

New alkyd coatings were prepared by addition of water-based polyaniline–4% CaCO₃ (PAC) nanocomposites into alkyd resin. Pure polyaniline (PANI) and PAC were synthesized using ultrasound assisted emulsion polymerization and added to alkyd resin to form nanocomposite coating. Nano CaCO₃ was added in different percentage ranging from 0% to 8% of monomer during the synthesis of polyaniline. XRD and TEM reveals that water repellent nano CaCO₃ is thoroughly dispersed in PANI matrix. The effect of PANI and PAC nanocomposite on mechanical and anticorrosion performance of alkyd coating was evaluated. An electrochemical measurement (Tafel Plots) shows that corrosion current I_corr was decreased from 0.89 to 0.03 μA/cm², when PAC nanocomposite was added to neat coatings. Positive shift of E_corr. also indicates that PAC nanocomposite acts as an anticorrosive additive to alkyd coating. Presence of water repellant nano CaCO₃ in PAC nanocomposite has exhibited dual effect, such as improvement in mechanical and anticorrosion properties. The experimental results have shown superiority of PAC nanocomposite over PANI when PAC nanocomposite added to alkyd coatings.     

Straightforward synthesis and structural characterization of the first alkoxy-zircono-silsesquioxanes — Potential models for zirconia–silica epoxidation catalysts: Molecular hybrid materials mimicking solution exchange in MOFs

The first representatives of alkoxy-zircono-silsesquioxane compounds, dinuclear [Cy₇Si₇O₁₂]Zr(ROH)(μ-OR)₂Zr(ROH)[O₁₂Si₇Cy₇], where R = ⁿPr, ⁿBu, ^tBu; Cy = c-C₆H₁₁, and [Cy*₇Si₇O₁₂]Zr(μ-ROH)(μ-OR)₂Zr[O₁₂Si₇Cy*₇], R = ^tBu; Cy* = c-C₅H₉, have been prepared with quantitative yield by interaction of the corresponding zirconium alkoxides with the cycloalkyl-substituted cage silsesquioxanes in hexane. The X-ray single crystal study of the n-butoxide derivative revealed that zirconium atoms are hexacoordinated with the 3 oxygen atoms of the cage ligand, 2 — from the bridging alkoxide groups and one — from the solvating alcohol molecule in the coordination sphere. The molecule is additionally supported by a hydrogen bond between the solvating alcohol and an oxygen atom belonging to the cage ligand coordinated by the other zirconium atom. The structures of produced silsesquioxanes display behavior typical for metal–organic frameworks as they crystallize initially as hexane clathrates, but lose the solvent on storage in inert atmosphere. This results in formation of empty channels situated along the c-axis.