Molecular Dynamic (MD) Simulations of Organic Modified Montmorillonite

This study complements the knowledge about organobentonites, which are intended to be new binders in foundry technology. In the developed materials, acrylic polymers act as mineral modifying compounds. Modification of montmorillonite in bentonite was carried out in order to obtain a composite containing a polymer as a lustrous carbon precursor. The polymer undergoes thermal degradation during the casting process, which results in the formation of this specific carbon form, ensuring the appropriate quality of the casting surface without negative environmental impact. The present paper reports the results of computational simulation studies (LAMMPS software) aimed at broadening the knowledge of interactions of organic molecules in the form of acrylic acid and acrylate anions (from sodium acrylate) near the montmorillonite surface, which is a simplified model of bentonite/acrylic polymer systems. It has been proven that the –COOH group promotes the adsorption of acrylic acid (AA) to the mineral surface, while acrylate ions tend to be unpredictably scattered, which may be related to the electrostatic repulsion between anions and negatively charged clay surfaces. The simulation results are consistent with the results of structural tests carried out for actual organobentonites. It has been proven that the polymer mainly adsorbs on the mineral surface, although it also partially intercalates into the interlayer spaces of the montmorillonite. This comprehensive research approach is innovative in the engineering of foundry materials. Computer simulation methods have not been used in the production of new binding materials in molding sand technology so far.

Metal-Organic Framework Reinforced Acrylic Polymer Marine Coatings

Metal-organic frameworks (MOFs), a class of crystalline, porous, 3D materials synthesized by the linking of metal nodes and organic linkers are rapidly emerging as attractive materials in gas storage, electrodes in batteries, super-capacitors, sensors, water treatment, and medicine etc. However the utility of MOFs in coatings, especially in marine coatings, has not been thoroughly investigated. In this manuscript we report the first study on silver MOF (Ag-MOF) functionalized acrylic polymers for marine coatings. A simple and rapid microwave technique was used to synthesize a two-dimensional platelet structured Ag-MOF. Field tests on the MOF reinforced marine coatings exhibited an antifouling performance, which can be attributed to the inhibition of marine organisms to settle as evidenced by the anti-bacterial activity of Ag-MOFs. Our results indicate that MOF based coatings are highly promising candidates for marine coatings.

Design and Optimization of Cationic Nanocapsules for Topical Delivery of Tretinoin: Application of the Box-Behnken Design, In Vitro Evaluation, and Ex Vivo Skin Deposition Study

Cationic nanocapsules represent a promising approach for topical delivery purposes. We elaborated on a novel formulation based on the cationic nanocapsules to enhance the pharmacodynamic efficacy, user compliance, and photostability of tretinoin (TTN). To achieve this goal, TTN nanocapsules were prepared by the nanoprecipitation method. In order to statistically optimize formulation variables, a Box-Behnken design, using Design-Expert software, was employed. Three independent variables were evaluated: total weight of the cationic acrylic polymer ( X 1 ), oil volume ( X 2 ), and TTN amount ( X 3 ). The particle size and encapsulation efficiency percent (EE%) were selected as dependent variables. The optimal formulation demonstrated spherical morphology under scanning electron microscopy (SEM), optimum particle size of 116.3 nm, and high EE% of 83.2%. TTN-loaded nanocapsules improved photostability compared to its methanolic solution. The in vitro release study data showed that tretinoin was released in a sustained manner compared to the free drug. The ex vivo skin permeation study demonstrated that greater drug deposition into the epidermal region rather than the deep skin was observed with a gel containing TTN-loaded nanocapsules than that of drug solution, respectively. The skin irritation test revealed that the nanoencapsulation of the drug decreased its irritancy compared to the free drug. These results revealed the promising potential of cationic nanocapsules for topical delivery of tretinoin

Effect of Various Types of Superplasticisers on Consistency, Viscosity, Structure and Long-Term Strength of Geopolymer Products

This article presents the results of research on the effect of plasticisers made based on four different compounds—melamine (M), naphthalene (NF), acrylic polymers (AP) and polycarboxylic ethers (PC)—added to the tested mixes in the amount of 2% of the fly ash (FA). The influence of superplasticisers (SPs) on the consistency of the fresh concrete was investigated using a flow table and a penetrometer, and the air voids content was determined by means of a porosimeter. Additionally, the influence of plasticisers on the viscosity of the paste was investigated using a rheometer. Hardened mortar that matured under two different conditions was also tested at elevated and room temperatures. The tested properties were 7-, 28- and 90-days compressive strength and internal microstructure viewed under a microscope. NF had the greatest viscosity-reducing effect while it increased the air void volume in the mix at the same time. The highest early and late strengths were obtained after curing in elevated temperature samples with an acrylic-polymer-based superplasticiser. However, the increased curing temperature of the samples only influenced the early strength results. Its effect was not visible after 90 days. The AP addition also had a significant impact on improving the consistency of the mixture. The addition of plasticisers did not affect the microstructure of the specimens.

A study of The use of Manuka Honey and Methylglyoxal to Impart Antimicrobial Activity to Wool Textiles and Polymers

<p><b>Methylglyoxal (MGO), which is an ingredient in New Zealand Manuka honey (MH) possesses unique antimicrobial properties against a broad range of bacteria. MGO has been determined to have a low minimum inhibitory concentration against bacteria. This provides a new opportunity to develop the use of this compound as a natural antimicrobial agent to impart such antimicrobial properties to wool textiles. This is the focus and detailed research work of this thesis. Also, its application to paper and polymer surfaces has been investigated briefly.</b></p> <p>Due to their protein-based structure and porosity, woollen textiles provide a hospitable host for the growth of microorganisms. This microbial growth on such textiles can pose an undesirable health risk to humans and can negatively affect textile sales. the textile market. Similarly, microbial growth on other substrates such as walls, floors and various equipment can also pose health risks. There are a number of antimicrobial treatments on the market, but with the move to more natural-based antimicrobial agents, there is an opportunity to capture the natural antimicrobial properties of MH and particularly the active ingredient MGO, as a natural antimicrobial agent in wool textiles and paper and polymer substrates.</p> <p>This research developed a novel approach and methodology to incorporate MH and also MGO itself as an isolated component and antimicrobial agent of MH, into the wool fibres and chemically bonding it to the fibre proteins. This approach commenced with determining the extent of uptake of MH, based on its MGO concentration, and MGO itself into wool fibres. The extent of MH and MGO uptake has been determined with High-Performance Liquid Chromatography (HPLC). This uptake was studied over a range of MH and MGO concentrations and temperatures using loose top wool, yarn and finished wool fabric. An increase in temperature from room temperature up to 80 °C resulted in significantly higher amounts of MGO and MH being absorbed by the wool. Also, higher concentrations of the initial MGO and MH solutions accelerated the uptake rates and resulted in higher uptake amounts. The relatively slow diffusion rate of MGO into the wool necessarily required a long period of time, up to 14 days, for the particular uptake to generally reach the saturation level. The maximum amounts of MH and MGO that were incorporated into wool fibres in this study were 21.2 mg g-1 and 299 mg g-1 wool, respectively.</p> <p>The chemical interactions between MGO and MGO in MH with the wool fibres have been characterised by Fourier-Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). FTIR spectra showed that the MGO absorption by the wool changed the intensity of particular peaks between 2,000 and 700 cm-1 characteristic of the wool proteins, and the NH stretching peaks of the wool at 3,270 cm-1. The TGA and DSC analyses showed a thermal stability of the wool after MGO absorption and the likely formation of new bonds, probably H-bonds, between the MGO and the wool. Confirming these findings, the MGOWool and MH-Wool showed a resistance against MGO leaching on washing with water, where less than 1% (relative) of MGO leached out. These results suggest the MGO is likely chemically bound to the wool fibres through hydrogen bonding.</p> <p>The MGO-Wool and also MGO-paper composites produced in a similar way with MGO-Wool, exhibited antimicrobial activities against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). The MGO-Wool showed bacteriostatic properties for all composites even after three months of being synthesised. This opens up potential applications for the use of MH and MGO in antimicrobial woollen apparel, medical textiles and bandages.</p> <p>In addition, MGO was incorporated into samples of an acrylic polymer NeoCryl® XK-98 and a polyurethane, Kamthane K-5000, polymer resin, respectively. The interaction of MGO with the respective polymer chains resulted in similar hydrogen bonding between MGO and the polymers. At high MGO concentrations this bonding was confirmed by the presence of a new endothermic peak in the DSC pattern. The addition of MGO also modified the polymer surface and resulted in a more hydrophobic surface with an increased water droplet contact angle of 87.5°. The new polymer compositeswere successfully tested against S. aureus and E. coli microbes and were shown to exhibit antimicrobial properties.</p>

A study of The use of Manuka Honey and Methylglyoxal to Impart Antimicrobial Activity to Wool Textiles and Polymers

<p><b>Methylglyoxal (MGO), which is an ingredient in New Zealand Manuka honey (MH) possesses unique antimicrobial properties against a broad range of bacteria. MGO has been determined to have a low minimum inhibitory concentration against bacteria. This provides a new opportunity to develop the use of this compound as a natural antimicrobial agent to impart such antimicrobial properties to wool textiles. This is the focus and detailed research work of this thesis. Also, its application to paper and polymer surfaces has been investigated briefly.</b></p> <p>Due to their protein-based structure and porosity, woollen textiles provide a hospitable host for the growth of microorganisms. This microbial growth on such textiles can pose an undesirable health risk to humans and can negatively affect textile sales. the textile market. Similarly, microbial growth on other substrates such as walls, floors and various equipment can also pose health risks. There are a number of antimicrobial treatments on the market, but with the move to more natural-based antimicrobial agents, there is an opportunity to capture the natural antimicrobial properties of MH and particularly the active ingredient MGO, as a natural antimicrobial agent in wool textiles and paper and polymer substrates.</p> <p>This research developed a novel approach and methodology to incorporate MH and also MGO itself as an isolated component and antimicrobial agent of MH, into the wool fibres and chemically bonding it to the fibre proteins. This approach commenced with determining the extent of uptake of MH, based on its MGO concentration, and MGO itself into wool fibres. The extent of MH and MGO uptake has been determined with High-Performance Liquid Chromatography (HPLC). This uptake was studied over a range of MH and MGO concentrations and temperatures using loose top wool, yarn and finished wool fabric. An increase in temperature from room temperature up to 80 °C resulted in significantly higher amounts of MGO and MH being absorbed by the wool. Also, higher concentrations of the initial MGO and MH solutions accelerated the uptake rates and resulted in higher uptake amounts. The relatively slow diffusion rate of MGO into the wool necessarily required a long period of time, up to 14 days, for the particular uptake to generally reach the saturation level. The maximum amounts of MH and MGO that were incorporated into wool fibres in this study were 21.2 mg g-1 and 299 mg g-1 wool, respectively.</p> <p>The chemical interactions between MGO and MGO in MH with the wool fibres have been characterised by Fourier-Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). FTIR spectra showed that the MGO absorption by the wool changed the intensity of particular peaks between 2,000 and 700 cm-1 characteristic of the wool proteins, and the NH stretching peaks of the wool at 3,270 cm-1. The TGA and DSC analyses showed a thermal stability of the wool after MGO absorption and the likely formation of new bonds, probably H-bonds, between the MGO and the wool. Confirming these findings, the MGOWool and MH-Wool showed a resistance against MGO leaching on washing with water, where less than 1% (relative) of MGO leached out. These results suggest the MGO is likely chemically bound to the wool fibres through hydrogen bonding.</p> <p>The MGO-Wool and also MGO-paper composites produced in a similar way with MGO-Wool, exhibited antimicrobial activities against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). The MGO-Wool showed bacteriostatic properties for all composites even after three months of being synthesised. This opens up potential applications for the use of MH and MGO in antimicrobial woollen apparel, medical textiles and bandages.</p> <p>In addition, MGO was incorporated into samples of an acrylic polymer NeoCryl® XK-98 and a polyurethane, Kamthane K-5000, polymer resin, respectively. The interaction of MGO with the respective polymer chains resulted in similar hydrogen bonding between MGO and the polymers. At high MGO concentrations this bonding was confirmed by the presence of a new endothermic peak in the DSC pattern. The addition of MGO also modified the polymer surface and resulted in a more hydrophobic surface with an increased water droplet contact angle of 87.5°. The new polymer compositeswere successfully tested against S. aureus and E. coli microbes and were shown to exhibit antimicrobial properties.</p>

SUBSTANTIATION OF THE EFFECTIVENESS OF A COMPREHENSIVE ALGORITHM OF ORTHOPEDIC REHABILITATION FOR THE PREVENTION OF PATHOLOGY OF THE ORAL MUCOSA

Актуальность : известно, что съемные ортопедические конструкции зубных протезов на протяжении долгого времени являются сложными раздражителями слизистой оболочки полости рта (СОПР). Грамотное выполнение технологических этапов изготовления, своевременная коррекция, рекомендации по профессиональной и индивидуальной гигиене полости рта и самих зубных протезов не всегда гарантируют отсутствие микробной колонизации на поверхности базисов условно-патогенными и патогенными представителями и воспалительной реакции со стороны тканей протезного ложа. При выборе базисного материала в качестве замещающей и восстанавливающей конструкции и при ортопедическом лечении в целом перед врачом-стоматологом встает вопрос о профилактике осложнений дисбиотического и воспалительного характера. Целью настоящего исследования является изучение влияния базисного материала съемных ортопедических конструкций на состояние тканей протезного ложа и доказательство эффективности предложенного авторами комплексного метода профилактики дисбиоза полости рта, влияющего на успех всего протезирования и качество стоматологического здоровья. Методика исследования: в клинике ортопедической стоматологии пациенты, нуждающиеся в съемном протезировании, были сформированы на 3 равноценные группы исследования, каждой из которых был предложен определенный алгоритм лечебно - профилактических мероприятий. Для решения поставленной задачи на предмет эффективности авторской методики далее использовали методику макрогистохимической реакции, что позволило оценить состояние слизистой оболочки под базисами съёмных протезов из акрилового полимера через сутки, 7 и 14 дней наложения съемного зубного протеза, также изучали количественный и качественный состав микробиоциноза слизистой оболочки полости рта. Результаты исследования: результаты клинико-микробиологического исследования слизистой оболочки протезного ложа указывают на целесообразность применения предложенной авторами методики ортопедической реабилитации для профилактики дисбиоза полости рта. Заключение : исследования, направленные на изучение данных проблем, особенно важны для повышения эффективности ортопедической реабилитации для снижения стоматологических осложнений у пациентов воспалительного и дисбиотического характера Relevance: it is known that removable orthopedic structures of dentures for a long time are complex irritants of the oral mucosa (SOPR). Competent implementation of the technological stages of manufacturing, timely correction, recommendations for professional and individual hygiene of the oral cavity and the dentures themselves do not always guarantee the absence of microbial colonization on the surface of the bases by conditionally pathogenic and pathogenic representatives and an inflammatory reaction from the tissues of the prosthetic bed. When choosing a basic material as a replacement and restoring structure and during orthopedic treatment in general, the dentist faces the question of preventing complications of a dysbiotic and inflammatory nature. The purpose of this study is to study the influence of the basic material of removable orthopedic structures on the state of the prosthetic bed tissues and to prove the effectiveness of the complex method of prevention of oral dysbiosis proposed by the authors, which affects the success of all prosthetics and the quality of dental health. Research methodology: in the clinic of orthopedic dentistry, patients in need of removable prosthetics were formed into 3 equivalent study groups, each of which was offered a certain algorithm of therapeutic and preventive measures. To solve the problem for the effectiveness of the author's technique, the method of macrohistochemical reaction was further used, which made it possible to assess the state of the mucous membrane under the bases of removable dentures made of acrylic polymer after a day, 7 and 14 days of applying a removable denture, and the quantitative and qualitative composition of microbiocinosis of the oral mucosa was also studied. Results of the study : the results of clinical and microbiological examination of the mucous membrane of the prosthetic bed indicate the expediency of using the method of orthopedic rehabilitation proposed by the authors for the prevention of oral dysbiosis. Conclusion: studies aimed at studying these problems are especially important for improving the effectiveness of orthopedic rehabilitation to reduce dental complications in patients of an inflammatory and dysbiotic nature

Predicting the Swelling Behavior of Acrylic Superabsorbent Polymers Used in Diapers

Acrylic polymer is a superabsorbent for water and widely used in diapers, in which its swelling behavior can be significantly affected by several factors, i.e., the time, temperature, pH, and salt concentration, and thus the product performance in the applications. In this work, the water absorption behavior of acrylic superabsorbent polymers by each of these individual factors was investigated. The results showed that the water absorbency increases with the pH in the range of 2 to ~7 and decreases when the pH continues to increase. However, it decreases with the increases in NaCl concentration in the solution. Moreover, more water can be absorbed by the acrylic polymers at the higher temperature. Based on a previously developed kinetic swelling model and the information from the above investigations, a semiempirical model for predicting the swelling behavior of superabsorbent polymers (SAPs) under different conditions has been developed. Data showed that the model can predict (with a relative error of <4.5%) the amount of water absorbed by acrylic SAPs under different swelling conditions. The model would be very helpful to the practical application in both product design and its performance evaluation.