Base Monomer Research Articles

Rural Space Aesthetics and Rural Construction Paths from the Perspective of the Montage: The Cases of Seven Villages in Guangdong, China

In the rural areas of China, construction is growing vigorously, and the question of how to realize the creative inheritance and development of these areas in the regional context, as well as the exploration of new construction methods and paths, are important problems. Nowadays, there are two developing trends in terms of research methods. Firstly, the boundaries between various disciplines are becoming increasingly blurred, and interdisciplinary theoretical reference has become an effective means of realizing innovation in this field. The other trend relates to the great development of digital technology, such as parameterization and spatial information technology. This technological innovation sheds new light on rural image construction. This study aims to draw on the montage art concept and organization techniques and to integrate the new technical language into the construction of new aesthetic orientations and context-related inheritance paths of rural historical places in China. Based on the aesthetic relevance of montage aesthetics to rural regional characteristics, the aesthetic cognition of the rural area in Guangdong is analyzed and demonstrated. Then, the strategies and methods used for the construction of rural area are established based on four layers, i.e., the narrative clues, base site pattern, spatial interfaces and monomer construction. The present research expands on the perspectives and methods of rural reconstruction, provides new ideas for the current rural practice, and is conducive to promoting the systematic study of rural construction theory.

A semi-covalent molecularly imprinted electrochemical sensor for rapid and selective detection of tiotropium bromide.

Tiotropium bromide (TIO) is a long-acting bronchodilator used in the treatment of chronic obstructive pulmonary disease (COPD) and asthma. Specifically, it is used to prevent patients from worsening breathing difficulties. In this study, a new TIO-imprinted electrochemical sensor was designed to detect TIO in serum and pharmaceutical samples. Methacryloyl-L-histidine-cobalt(II) [MAH-Co(II)] has been used as a metal-chelating monomer for synthesizing selective molecularly imprinted polymer (MIP). MIP film has been developed on glassy carbon electrodes using MAH-Co(II) as the functional monomer, 2-hydroxyethyl methacrylate (HEMA) as the basic monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker in the photopolymerization method. The surface characterization of the developed MAH-Co(II)@MIP/GCE electrochemical sensor was done using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Also, the electrochemical behavior of the sensor was provided by differential pulse voltammetry (DPV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. Under optimized experimental conditions, the linearity range was in the range of 10-100 fM, and the limit of detection (LOD) and limit of quantitation (LOQ) values were calculated as 2.73 fM and 9.75 fM, respectively. The MAH-Co(II)@MIP/GCE sensor was used to precisely determine TIO in capsule and commercial serum samples. The results demonstrated that the MIP could specifically recognize TIO compared to structurally related drugs and could be reliably applied to the direct determination of drugs from real samples.

Synthesis of a Zinc Hydroxystannate/Sepiolite Hybrid Additive to Avoid Fire Propagation and Reduce Smoke Emission of EPDM Rubber Nanocomposites.

A zinc hydroxystannate/sepiolite (SEPZHS) hybrid additive was successfully prepared following a facile wet chemical route synthesis where zinc hydroxystannate (ZHS) nanoparticles were grown on the sepiolite’s surface. SEPZHS particles have a fibrillar structure with ZHS nanoparticles homogeneously dispersed and with significantly smaller particle sizes than the synthesized ZHS nanoparticles alone. Sepiolite and SEPZHS were organically modified and introduced in a basic ethylene propylene diene monomer rubber (EPDM) formulation for cable to evaluate the nanocomposite behavior under direct fire sources. The results confirmed the synergistic effect of the hybrid SEPZHS additive in the formation of a most stable and efficient char barrier, thus improving the flame-retardant behavior of EPDM nanocomposite in terms of heat emission, with reductions of more than 40% in the peak of Heat Release Rate (cone calorimeter test), and smoke suppression, with more than 25% reduction in the Total Smoke Production and Smoke Density parameters (smoke chamber test). Moreover, the addition of sepiolite-based additives increased the mechanical properties (hardness) of the nanocomposites, as a result of the matrix reinforcement. This suggests that the SEPZHS hybrid additive may provide a promising option for a new, cost-effective, eco-friendly, yet efficient flame-retardant solution.

Antibacterial waterborne polyacrylate coated fabric with underwater superoleophobicity and underoil superhydrophobicity for continuous oil/water separation

Antibacterial superamphiphilic materials with green and facile preparation process have attracted extensive attention in oil/water separation. Herein, an antibacterial waterborne polyacrylate (AWBPA) composed of [2-(methacryloyloxy)-ethyl] trimethylammonium chloride (METAC) and basic acrylate monomers has been successfully developed using the emulsion polymerization method and water as the sole solvent. By sequentially simple dip-coating of polyethyleneimine (PEI) and AWBPA, the polyester fabric can be endowed with the superamphiphilic and antibacterial properties. By prewetting with water/oil, the modified fabric holds underwater superoleophobicity/underoil superhydrophobicity, and can be used for continuous separation of light oil/water, heavy oil/water and light oil/water/heavy oil mixtures. Importantly, these modified fabrics have high antibacterial activity (99.3 ± 0.2 %), and can maintain its underwater superoleophobicity and underoil superhydrophobicity even after immersion in corrosive solution for 15 d, 100 g sand impact and 200-cycle adhesive tape-peeling, and are suitable for practical large-scale production applications.

Research on Mesoscale Nucleation and Growth Processes in Solution Crystallization: A Review

In recent studies, the existence of mesoscale precursors has been confirmed in crystallization. Different from the classical crystallization theory, which only considers the sequential attachment of basic monomers (atoms, ions, or molecules), the nonclassical crystallization process involving precursors such as prenucleation clusters, nanoparticles, and mesocrystals is more complicated. The mesoscale structure is important for the quantitative description and directional regulation of the solution crystallization process. It is necessary to explore the mechanism by the mesoscale scientific research methods on the base of traditional chemical engineering and process system engineering research methods. Therefore, the paper reviews several representative nonclassical nucleation and growth theories, mainly including two-step nucleation theory, prenucleation clusters theory, particle agglomeration theory, amorphous precursor growth theory, particle attachment growth theory and mesocrystal growth theory. Then, the mesoscale structure and its spatiotemporal dynamic behavior are discussed, and the application of the EMMS model in the nucleation and growth process is analyzed. Finally, we put forward our views on the prospect of the paradigms and theoretical innovations of using mesoscale methods in crystal nucleation and growth.

Effect of Fluorinated Comonomer, Polymerizable Emulsifier, and Crosslinking on Water Resistance of Latex Coatings

Common latex coatings suffer from poor water resistance, which often limits their practical application. This paper reports on the preparation of polyacrylate latexes using various approaches to tune the water resistance, wettability, and surface properties of their coating films. The mutual effects of fluorinated monomer copolymerization, emulsifier type (polymerizable and general), and intra- or interparticle covalent crosslinking (due to allyl methacrylate copolymerization and a keto-hydrazide reaction, respectively) were studied. The polyacrylate latexes were synthesized through a two-step semicontinuous emulsion polymerization of 2,2,2-trifluoroethyl methacrylate, butyl acrylate, methyl methacrylate, and methacrylic acid as the basic monomers. The fluorinated monomer was incorporated into the second-step polymer (at a content of 30 wt.% based on the second-step monomer feeds). The water resistance, wettability, and surface properties of the coating films were evaluated with focus on the water absorption, water whitening, water contact angle, and surface topography using atomic force microscopy. It was found that highly water-resistant and hydrophobic coatings that possessed a self-healing ability were prepared, provided that the polymerizable emulsifier and the fluorinated monomer were involved in the latex synthesis, along with the intra- and interparticle covalent crosslinking.

The production of monomers by dehydrogenation at PJSC «Nizhnekamskneftekhim»

The paper describes the production of base monomers by dehydrogenation at PJSC «Nizhnekamskneftekhim». Special emphasis is made on the development of advanced domestic catalysts in cooperation with Kazan Federal University. Drawbacks of the existing catalytic systems and possible variants of their improvement are described.

How chemical structure and composition impact on the release of salt-like drugs from hydrophobic matrices: Variation of mechanism upon adding hydrophilic features to PMMA

The adaptation of polymeric matrices to tailor their drug release characteristics requires the complete understanding of the mechanism involved. We thus explored how chemical and structural modifications of film forming polymethyl methacrylate (PMMA), a polymer often used for its biocompatibility, impact on its release features. Comparing Diclofenac Sodium (NaD) salt release from pure PMMA, mPEG–b–(PMMA)n, and mPEG–b–(PMMA–ran–DMAEMA)n polymeric films (n = 1, 2), we evidenced the impact of successive polymer modifications on the release rate and equilibrium. Thus, PEGylation increased both the release rate and the amount of NaD desorbed (up to 53%) introducing, however, a “burst phase” not present with pure PMMA; the latter released only 3% of NaD. The presence of DMAEMA in mPEG–b–(PMMA–ran–DMAEMA)n, instead, decreased the release rates and led to the complete NaD desorption at physiological conditions. We rationalized our observations with electronic structure calculations and lattice stochastic simulations. The former suggested a tendency for NaD to accumulate in the hydrophilic mPEG portion via the coordination of the sodium cation in low polarity casting solvents. Stochastic simulations, instead, suggested that mPEG ought to form small domains on the film surface favouring fast NaD desorption in the release medium. Importantly, DMAEMA reduced the NaD tendency to accumulate in the mPEG portion due to the coordination on MMA–DMAEMA motifs. In physiological conditions (i.e., pH ≃ 6.4), the basic monomer also dampens the burst phase and reduces the release rate compared to the other matrices thanks to salt bridges between the drug and amino group.

Sequential assembly enabled surface precise imprinting on Janus nanosheets for highly specific separation of adenosine 5′-monophosphate

• The sequential imprinting assembly strategy was demonstrated to precisely control the imprinting process. • Janus amphiphilic polymer nanosheets acted as the carrier of J-MIPs to simplify the collection process. • Binding sites with high affinity to AMP of J-MIPs accounted for about 76.71% of the total sites. • J-MIPs could be used for selective enrichment of targeted AMP in complex biological samples. Precise control of imprinting processes and reasonable selection of molecularly imprinted polymers (MIPs) carriers are essential for realizing highly selective and fast separation. In this work, Janus polymer nanosheets (J-PNs) with different wettabilities on two sides were synthesized by self-polymerizing dopamine based on octadecylamine (ODA) lamellae with a bilayer structure, followed by a sequential imprinting assembly of low pKa boronic acid and pyrimidine base monomers on the hydrophilic side of J-PNs to prepare Janus imprinting sorbents (J-MIPs) for highly specific separation of adenosine 5′-monophosphate (AMP). The sequential assembly strategy integrated two different functional monomers together to simultaneously interact with the surrounding template AMP molecule and to precisely control the imprinting site orientation, enabling the resulting J-MIPs with strong and specific binding toward AMP. Janus amphiphilic J-MIPs can be well fixed at the dodecane/water interface, which was benefit for their fast recycle and simple regeneration, and the uptake amount of the fifth adsorption/elution cycle was 86.08% of the first one. The equilibrium time and maximum adsorption capacity of tailor-made J-MIP were 4.0 h and 13.69 μmol g −1 at 298 K, respectively. Taking the advantage of cooperative multi-point interaction, binding sites with high affinity to AMP accounted for about 76.71% of the total sites, and the high imprinting factor (2.182) of the J-MIP against non-imprinted counterpart was observed. In addition, 61.30% of AMP in spiked human serum sample can be selectively extracted by J-MIPs, due to the highly specific receptor sites from sequential imprinting assembly.

Optical characteristics of experimental dental composite resin materials

ObjectivesTo derive the K-M optical coefficients of experimental composites and compare the inherent CIE L*, a* and b* color parameters, translucency parameters and both perceptibility and acceptability thresholds. MethodsExperimental composites were prepared with 4 base-monomers: Bis-GMA, UDMA, Bis-EMA and Fit852 with TEGDMA used as a co-monomer and 3 filler:resin fractions (50:50wt%, 60:40wt% and 70:30wt%). The optical absorption (K) and scattering (S) coefficients over the visible spectra were derived. Corrected reflectivity spectra were calculated using the corrected Kubelka-Munk reflectance model and were used to calculate CIE color parameters (X, Y, Z) values. Translucency parameter (TP) was calculated using the CIEDE2000 color difference. A three-way repeated measures ANOVA was used to analyze the CIE L*a* and b* color parameters at infinite thickness. A two-way ANOVA was used to analyze the translucency parameter at 2 mm thickness. Pairwise comparisons were assessed using Bonferroni-corrected Student's t-tests. For all statistical testing α = 0.05 was used. Color parameters (ΔE00) were calculated for every experimental composite using the CIEDE2000 color differences. Perceptibility threshold (PT), acceptability threshold (AT) and translucency differences (ΔTP) were used to compare experimental composites in both filler fraction within every resin and every resin within each filler fraction. ResultsThe statistical analysis revealed a 3-way interaction (P < 0.0001) between base monomer, filler and direction factors. For the translucency parameter, when comparing filler fraction within base monomers, there were statistically significant differences between the filler fraction within all base monomers. The analysis of color differences (ΔE00) of base monomers within filler fraction revealed that the comparison between experimental composites where beyond the acceptability threshold. The comparison of the differences in translucency parameter (ΔTP) of base monomers within filler fraction were beyond the perceptibility threshold, except between base monomers UT and FT. SignificanceDifferent base monomer and filler fraction combination influences the optical characteristics of experimental composites such as: light transmission, translucency, and color appearance.

Effects of Monomer Composition of Urethane Methacrylate Based Resins on the C=C Degree of Conversion, Residual Monomer Content and Mechanical Properties.

(1) Background: This study investigated the influence of Bis-GMA, TEGDMA, UDMA, and two different polyethylene glycol (PEG)-containing, UDMO-based co-monomers on the Young’s modulus and flexural strength, degree of methacrylate C=C double bond conversion and residual monomer elution of experimental dental resins. (2) Methods: Urethane methacrylate-based monomer was synthesised via a radical chain growth polymerization mechanism using PEG in order to improve the mechanical properties. Dental resins were formulated using Bis-GMA, UDMA, or UDMO as base monomers combined with TEGDMA as a dilution monomer and DMAEM + CQ as the photo-initiator system. Degree of conversion (DC), mechanical properties, and residual monomer content of light-activated methacrylate resin formulations were evaluated and statistically analysed by ANOVA and a Tukey’s test. (3) Results: PEG-containing UDMO resins had lower Young’s modulus and elastic strength than UDMA-derived resin for all irradiation times. The highest DC (67,418%) was observed for the PEG-containing UDMO-based resin formulation when light cured for 40 s. For all samples, DC increased with the photo-polymerization time. The amount of residual monomer decreased after increasing the light-curing period from 20 to 40 s, resin with UDMO content 0.01 mol of PEG having the smallest amount of free eluted monomer. (4) Conclusions: A strong structure–property relationship exists in photo-cured dimethacrylate-based dental resins. The time and quantity of the photochemical initiation system can influence the physical–mechanical properties of the resins but also the monomers in their composition.

Comparative investigation of tribological behavior of hybrid dental restorative composite materials

Dental restorative composite materials require appropriate tribological characteristics to bear different stresses in the oral environment. This study inspects the tribological aspects of micro-nano parttticulate filled dental restorative composite materials. Nano-hydroxyapatite (nHA) (0, 2, 4, 6, and 8 wt%), alumina (20 wt%), and titanium oxide (20 wt%) were reinforced in the form of hybrid into the dental resin matrix. The dental resin matrix was fabricated from a base monomer, diluents, initiator, and accelerator. Two body sliding wear tests were conducted by rubbing the prepared nano-composites against a Carbon steel-EN 31 counter plate. ANOVA was used to find significant statistical factors. Besides, the wear mechanisms were clarified via scanning electron microscopy. EDS (energy dispersive spectroscopy) analysis was also done to identify the organic and inorganic groups incorporated in the dental composite samples. The results showed that incorporating high amounts of nHA nanoparticles can improve the wear properties of dental composites. The results of specific wear rate were found significant as per literature.

Comparison of genomes of different species of coronaviruses using spectra of periodicities

In the genomes of different organisms, there are periodicities, i.e. fragments of DNA (RNA)-sequences formed by tandem repetition of the basic monomer (period). The spectra of periodicities with lengths exceeding the ‘noise’ threshold are quite compact and visible even for complete genomes. This makes them an acceptable tool for differentiating closely related objects. The objects of analysis in this work are the periodicities at genomes of three species of coronavirus: MERS, SARS, and SARS-CoV-2. It has been shown that there are markers in the form of periodicities that make it possible to distinguish between these species of coronaviruses. None of the periodicities identified in the genomes of the MERS species (except for the poly-a tract in the 3‘UTR) is found in the genomes of SARS and SARS-CoV-2 and vice versa. Revealed periodicities common to SARS and SARS-CoV-2, as well as inherent only to genomes of one species. The number of periodicities in SARS and SARS-CoV-2 significantly exceeds the number of periodicities in random sequences. The periodicities found in almost all genomes of only ‘their’ species are of the greatest interest in terms of revealing the pathogenic potential of the virus.

Evaluation of diametral tensile and compressive strengths of different types of nanocomposites for dental applications

This study aims to evaluate the diametral tensile strength (DTS) and compressive strength (CS) of restorative composite resins that applied as restorative materials in the field of dentistry. The composites were prepared from different sets of monomers which divided into six groups (A, B, C, D, E, and F) according to the type and ratios of monomers used in preparing the matrix materials, excepted the basic monomer (2, 2 propyl bisphenol glycidyl dimethacrylate (Bis-GMA)) that added at constant ratio (40 wt%), in addition tothe nano-inorganic fillers [SiO2, ZrO2, HA, and Al2O3] which adding individually. Ninety specimens were prepared for diametral tensile strength test, which divided into six groups according to the prepared resin matrix and five sub-divided groups according to types of fillers of prepared composites, and for compressive strength test, the same numbers of specimens were prepared. In the beginning, the diametral tensile strength (DTS) and compressive strength of the prepared matrices were determined and then study the effect of adding the nano-inorganic fillers on the results of these properties for the prepared dental restorations nanocomposites materials. The results show that the composites based on resin matrix of group (D) having the selected monomers (BIS-GMA, meth acrylamide, methacrylic acid, and 1–6 hexanediol methacrylate) that reinforced with silica nanoparticle have higher properties as compared with other types of the prepared nanocomposite, where these values reached to (54 MPa and 174 MPa) for diametral tensile strength and compressive strength, respectively.

Metal-Organic Frameworks as Versatile Media for Polymer Adsorption and Separation.

Molecular recognition is of paramount importance for modern chemical processes and has now been achieved for small molecules using well-established host-guest chemistry and adsorption-science principles. In contrast, technologies for recognizing polymer structure are relatively undeveloped. Conventional polymer separation methods, which are mostly limited in practice to size-exclusion chromatography and reprecipitation, find it difficult to recognize minute structural differences in polymer structures as such small structural alterations barely influence the polymer characteristics, including molecular size, polarity, and solubility. Therefore, most of the polymeric products being used today contain mixtures of polymers with different structures as it is challenging to completely control polymer structures during synthesis even with state-of-the-art substitution and polymerization techniques. In this context, development of novel techniques that can resolve the challenges of polymer recognition and separation is in great demand, as these techniques hold the promise of a new paradigm in polymer synthesis, impacting not only materials chemistry but also analytical and biological chemistry.In biological systems, precise recognition and translation of base monomer sequences of mRNA are achieved by threading them through small ribosome tunnels. This principle of introducing polymers into nanosized channels can possibly help us design powerful polymer recognition and separation technologies using metal-organic frameworks (MOFs) as ideal and highly designable recognition media. MOFs are porous materials comprising organic ligands and metal ions and have been extensively studied as porous beds for gas separation and storage. Recently, we found that MOFs can accommodate large polymeric chains in their nanopores. Polymer chains can spontaneously infiltrate MOFs from neat molten and solution phases by threading their terminals into MOF nanochannels. Polymer structures can be recognized and differentiated due to such insertion processes, resulting in the selective adsorption of polymers on MOFs. This enables the precise recognition of the polymer terminus structure, resulting in the perfect separation of a variety of terminal-functionalized polymers that are otherwise difficult to separate by conventional polymer separation methods. Furthermore, the MOFs can recognize polymer shapes, thus enabling the large-scale separation of high purity cyclic polymers from the complex crude mixtures of linear polymers, which are used as precursor materials in common cyclization reactions. In solution-phase adsorption, many factors, including molecular weight, terminal groups, polymer shape, polymer-MOF interaction, and coexisting solvent molecules, influence the selective adsorption behavior; this yields a new liquid chromatography-based polymer separation technology using an MOF as the stationary phase. MOF-packed columns, in which a novel separation mode based on polymer insertion into the MOF operates under a dynamic insertion/rejection equilibrium at the liquid/solid interface, exhibited excellent polymer separation capability. The polymer recognition principle described in this study thus has a high probability for realizing previously unfeasible polymer separations based on monomer composition and sequences, stereoregularity, regioregularity, helicity, and block sequences in synthetic polymers and biomacromolecules.

Synthesis of Poly(ε-caprolactone) Diacrylate for Micelle-Cross-Linked Sodium AMPS Hydrogel for Use as Controlled Drug Delivery Wound Dressing.

This study focuses on the synthesis of poly(ε-caprolactone) diacrylate (PCLDA) for the fabrication of micelle-cross-linked sodium AMPS wound dressing hydrogels. The novel synthetic approach of PCLDA is functionalizing a PCL diol with acrylic acid. The influences of varying the PCL diol/AA molar ratio and temperature on the suitable conditions for the synthesis of PCLDA are discussed. The hydrogel was synthesized through micellar copolymerization of sodium 2-acrylamido-2-methylpropane sulfonate (Na-AMPS) as a basic monomer and PCLDA as a hydrophobic association monomer. In this study, an attempt was made to develop new hydrogel wound dressings meant for the release of antibacterial drugs (ciprofloxacin and silver sulfadiazine). The chemical structures, morphology, porosity, and water interaction of the hydrogels were characterized. The hydrogels' swelling ratio and water vapor transmission rate (WVTR) showed a high swelling capacity (4688-10753%) and good WVTR (approximately 2000 g·m-2·day-1), which can be controlled through variation of the PCLDA concentration. The mechanical property results confirmed that PCLDA improved the mechanical properties of the hydrogel; the stress increased from 37 to 68 kPa, and the strain increased from 198 to 360% with increasing PCLDA (0-30% wt of Na-AMPS). These hydrogels presented no cytotoxicity based on over 70% cell viability responses (L929 fibroblasts) using an in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Additionally, the drug release mechanism, kinetic models, and antibacterial activity were determined. The results demonstrated that antibiotics were released from the hydrogel with a Fickian diffusion mechanism and antibacterial activity against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus). Based on the results obtained, and bearing in mind that further progress still needs to be made, the fabricated hydrogels show considerable potential for meeting the stringent property requirements of hydrogel wound dressings.

A predictive model for salt nanoparticle formation using heterodimer stability calculations

Abstract. Acid–base clusters and stable salt formation are critical drivers of new particle formation events in the atmosphere. In this study, we explore salt heterodimer (a cluster of one acid and one base) stability as a function of gas-phase acidity, aqueous-phase acidity, heterodimer proton transference, vapor pressure, dipole moment and polarizability for salts comprised of sulfuric acid, methanesulfonic acid and nitric acid with nine bases. The best predictor of heterodimer stability was found to be gas-phase acidity. We then analyzed the relationship between heterodimer stability and J4×4, the theoretically predicted formation rate of a four-acid, four-base cluster, for sulfuric acid salts over a range of monomer concentrations from 105 to 109 molec cm−3 and temperatures from 248 to 348 K and found that heterodimer stability forms a lognormal relationship with J4×4. However, temperature and concentration effects made it difficult to form a predictive expression of J4×4. In order to reduce those effects, heterodimer concentration was calculated from heterodimer stability and yielded an expression for predicting J4×4 for any salt, given approximately equal acid and base monomer concentrations and knowledge of monomer concentration and temperature. This parameterization was tested for the sulfuric acid–ammonia system by comparing the predicted values to experimental data and was found to be accurate within 2 orders of magnitude. We show that one can create a simple parameterization that incorporates the dependence on temperature and monomer concentration on J4×4 by defining a new term that we call the normalized heterodimer concentration, Φ. A plot of J4×4 vs. Φ collapses to a single monotonic curve for weak sulfate salts (difference in gas-phase acidity &gt;95 kcal mol−1) and can be used to accurately estimate J4×4 within 2 orders of magnitude in atmospheric models.

Synthesis of phosphate and silane-based conjugated polymers derived from bis-azomethine: Photophysical and thermal characterization

Polyazomethines including phosphate and silane groups were studied in this work. In the first step, two Schiff base monomers, SBs with two hydroxyl functional groups were synthesized as a result of a condensation reaction between diamine and aldehyde. Then, Schiff bases were polymerized by HCl elimination between hydroxyl groups of the SBs and chlorine of phenyl dichlorophosphate (P) or dichlorodiethylsilane (Si) to obtain two different polyazomethines for each. FT-IR, 1H NMR, 13C NMR and thermal analysis were utilized to characterize the synthesized SBs, P-polyazomethines and Si-polyazomethines. The optical band gap values (Eg) of the synthesized P-polyazomethines and Si-polyazomethines were calculated using UV–Vis spectrophotometer. The study of solvent effects on the absorption of P-polyazomethines and Si-polyazomethines was also included into this work. Low band gaps of the synthesized polyazomethines could be evaluated as semi-conductive material for the production of electronic and optoelectronic materials. Photoluminescence (PL) measurements revealed that PP1 gave a greenish-yellow color emission upon excitation at blue light of 480 nm with a 16.2% of quantum yield although the response of SiP1 had white light emitting property. Besides, PP2 had multicolor emission property and SiP2 had white light emitting property. No obvious fluorescence changes were observed within 3600 s under the same conditions, serving as evidence of stability of PL emission of PP1, SiP1, PP2 and SiP2 to be steady along with wavelength of the exciting light. Thermal properties of the synthesized polyazomethines indicated that they were thermal stable materials up to 300 °C. The residual of P-polyazomethines and Si-polyazomethines was observed between 39.8% and 64.7% at 1000 °C.

Influence of Alumina Nanoparticles on the Mechanical Properties of a Bioresin Composite

A significant part of the research and production activities is represented in the field of bioengineering by the biomaterials used in hard tissue restorations. They are of great interest in dental science, intending to improve technological aspects, monitoring their biological responses to the living organisms, but also to redesign economic aspects, beginning with the choice of raw materials. In the present work, light-curing composite biomaterials were made from a composite polymer matrix consisting of specific concentrations of bisphenol A-glycidyl methacrylate base monomer (Bis-GMA), a mixture of two co-monomers, triethylene glycol dimethacrylate and ethoxylated bisphenol A-dimethacrylate (TEGDMA/BisEMA), and two alumina nanopowder concentrations (5 wt.% and 10 wt.%). These materials were mechanically tested for flexural strength and compressive strength. The structural analysis of these materials consisted of SEM microscopy and EDX elementary mapping. In order to extract 3D projections of sample surfaces, but also to produce indicative values of their roughness, the SEM micrographs were processed with open-source software. In order to observe a clear evolution of the mentioned properties, the composite biomaterials were compared with materials formed only with the Bis-GMA/TEGDMA/BisEMA composite, and with a commercial composite resin, Filtek™ Supreme Ultra Universal Restorative, also. The findings showed an increase in the mechanical properties of the materials manufactured concerning the concentration of nanoparticles of aluminum. EDX analyzes confirmed the good homogeneity of nanoparticles in the polymer matrix. Mechanical properties of the manufactured nanocomposite biomaterials were reported 28.8 % higher than the control biomaterial. The comparison results with the commercial resin composite are encouraging.

Metagenomic Discovery and Characterization of Multi-Functional and Monomodular Processive Endoglucanases as Biocatalysts

Biomass includes cellulose, hemicelluloses, pectin and lignin; constitutes the components of dietary fibre of plant and alge origins in animals and humans; and can potentially provide inexhaustible basic monomer compounds for developing sustainable biofuels and biomaterials for the world. Development of efficacious cellulases is the key to unlock the biomass polymer and unleash its potential applications in society. Upon reviewing the current literature of cellulase research, two characterized and/or engineered glycosyl hydrolase family-5 (GH5) cellulases have displayed unique properties of processive endoglucanases, including GH5-tCel5A1 that was engineered and was originally identified via targeted genome sequencing of the extremely thermophilic Thermotoga maritima and GH5-p4818Cel5_2A that was screened out of the porcine hindgut microbial metagenomic expression library. Both GH5-tCel5A1 and GH5-p4818Cel5_2A have been characterized as having small molecular weights with an estimated spherical diameter at or &lt; 4.6 nm; being monomodular without a required carbohydrate-binding domain; and acting as processive β-1,4-endoglucanases. These two unique GH5-tCel5A1 and GH5-p4818Cel5_2A processive endocellulases are active in hydrolyzing natural crystalline and pre-treated cellulosic substrates and have multi-functionality towards several hemicelluloses including β-glucans, xylan, xylogulcans, mannans, galactomannans and glucomannans. Therefore, these two multifunctional and monomodular GH5-tCel5A1 and GH5-p4818Cel5_2A endocellulases already have promising structural and functional properties for further optimization and industrial applications.