Journal articles on the topic 'Surface active agents – Analysis'
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Matsumoto, Kozo, Shin Tsuge, and Yukio Hirata. "Analysis of non-ionic surface active agents by supercritical fluid chromatography/mass spectrometry." Journal of the Mass Spectrometry Society of Japan 35, no. 1 (1987): 15–22. http://dx.doi.org/10.5702/massspec.35.15.
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Tubtimsri, Sukannika, and Yotsanan Weerapol. "Development of Nifedipine Amorphous Solid Dispersion Composed of Surface-Active Agents." Key Engineering Materials 901 (October 8, 2021): 35–39. http://dx.doi.org/10.4028/www.scientific.net/kem.901.35.
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The amorphous solid dispersions (ASDs) containing amino methacrylate copolymer and surface-active agents were prepared to improve the nifedipine (NDP) dissolution. The different types of surface-active agent i.e., polysorbates 80, sodium lauryl sulfate (SLS) and polyethylene glycol (PEG) 400 were used. In order to evaluate the ASDs formulation,powder X-ray diffractometry and thermal analysis to characterize NDP crystallinity in ASDs and the dissolution study of NDP have been performed to compare the dissolution profiles. The ASDs were kept for 6 months to investigate the stability. In the X-ray diffraction pattern, no peak was observed in all samples of ASDs. No peak was found in sample of all ASDs from the thermograms. These results suggest that the drug may be molecularly dispersed in matrix of amino methacrylate copolymer. The drug dissolution at 120 min, from ASDs without surface-active agent and NDP powder were 58.31% and 17.95%, respectively. The dissolved NDP from ASDs composed of SLS, polysorbate 80 and PEG400 were 96.25%, 88.86% and 75.32%, respectively. These results may occur due to the reduction of surface tension, the addition of the low amount of high efficiency of surface-active agent e.g., SLS (compared with PEG400 and polysorbate 80) provided the higher NDP dissolution. The content analysis of NDP in selected ASDs was studied at the end of 3 and 6 months, the NDP content remained unchanged after storage.
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Matysik, J., H. Kroszka, and A. Persona. "Analysis of Cationic Surface Active Agents Using DME and Its Relevance to Their Adsorption." Adsorption Science & Technology 4, no. 1-2 (March 1987): 53–57. http://dx.doi.org/10.1177/0263617487004001-205.
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The paper describes an application of dropping mercury electrode (DME) for analytical determination of certain cationic surface active agents and their mixtures and presents obtained thermodynamical data of adsorption of investigated substances.
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Thakur, Rachna, Sandya Devi S. Patil, Anil Kush, and K. Madhu. "SEM Analysis of Residual Dentin Surface in Primary Teeth Using Different Chemomechanical Caries Removal Agents." Journal of Clinical Pediatric Dentistry 41, no. 4 (January 1, 2017): 289–93. http://dx.doi.org/10.17796/1053-4628-41.4.289.
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Background: The purpose of this in vitro study was to analyze the residual dentinal surfaces following caries removal using two chemomechanical methods (Papacarie Duo and Carie Care), by scanning electron microscopy (SEM). Study design: Twenty extracted primary molars with active occlusal carious lesions were randomly assigned two groups depending on the CMCR agent used for the caries excavation – Group 1 – with Papacarie Duo and Group – 2 with Carie Care. After the caries excavation, the specimens were subjected to SEM analysis. Results: Though both the agents showed the minimal smear layer with the patent dentinal tubules, Carie care showed patent dentinal tubules with a clearly exposed peritubular and intertubular collagen network. Conclusion: Carie Care treated surface exhibited better surface morphology of residual dentin.
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Kurochkin, I., I. Ryzhikov, A. Sarychev, K. Afanasiev, I. Budashov, M. Sedova, I. Boginskaya, S. Amitonov, and A. Lagarkov. "New SERS-active junction based on cerium dioxide facet dielectric films for biosensing." Advanced Electromagnetics 3, no. 1 (October 23, 2014): 57. http://dx.doi.org/10.7716/aem.v3i1.266.
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Further enhance of the Raman scattering is the priority for the development of the modern molecular diagnostic methods. Expected increasing in detection sensitivity of the biological and chemical agents provides substantial progress in such areas as: proteomics (discovery of new disease markers), pharmacokinetics of drugs, analysis of toxins and infections agents, drug analysis, food safety, and environmental safety.In this paper we investigated the possibility of the facet structures, based on cerium dioxide to further enhance the SERS signal. During the studies a new metamaterial was developed. The metamaterial is based on the facet cerium dioxide films and plasmonic nanoparticles that are immobilized on its surface. The new metamaterial provides additional SERS signal amplification factor of 211. Thus developed material offers the prospect of increasing the sensitivity and selectivity of biochemical and immunological analysis.
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Shang Guan, Chang Cheng, Xing Long Zhou, Dong Yang Sun, and Peng Xiang Zhang. "Study on Flotation of Refractory Phosphorite at Normal Temperature." Applied Mechanics and Materials 522-524 (February 2014): 1488–92. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.1488.
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This article unfolded experiments of three kinds of normal temperature collector applying to a refractory phosphorite.The results showed that CC-1(the collector self-prepared) had higher collecting capacity,selecting feature than other collectors.Meanwhile,analysis of the action mechanism of surface active agents to increase effect and dissolving in CC-1 had been made.
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Gutierrez, Tony, Gordon Morris, Dave Ellis, Barbara Mulloy, and Michael D. Aitken. "Production and characterisation of a marine Halomonas surface-active exopolymer." Applied Microbiology and Biotechnology 104, no. 3 (December 7, 2019): 1063–76. http://dx.doi.org/10.1007/s00253-019-10270-x.
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AbstractDuring screening for novel emulsifiers and surfactants, a marine gammaproteobacterium, Halomonas sp. MCTG39a, was isolated and selected for its production of an extracellular emulsifying agent, P39a. This polymer was produced by the new isolate during growth in a modified Zobell’s 2216 medium amended with 1% glucose, and was extractable by cold ethanol precipitation. Chemical, chromatographic and nuclear magnetic resonance spectroscopic analysis confirmed P39a to be a high-molecular-weight (~ 261,000 g/mol) glycoprotein composed of carbohydrate (17.2%) and protein (36.4%). The polymer exhibited high emulsifying activities against a range of oil substrates that included straight-chain aliphatics, mono- and alkyl- aromatics and cycloparaffins. In general, higher emulsification values were measured under low (0.1 M PBS) compared to high (synthetic seawater) ionic strength conditions, indicating that low ionic strength is more favourable for emulsification by the P39a polymer. However, as observed with other bacterial emulsifying agents, the polymer emulsified some aromatic hydrocarbon species, as well as refined and crude oils, more effectively under high ionic strength conditions, which we posit could be due to steric adsorption to these substrates as may be conferred by the protein fraction of the polymer. Furthermore, the polymer effected a positive influence on the degradation of phenanthrene by other marine bacteria, such as the specialist PAH-degrader Polycyclovorans algicola. Collectively, based on the ability of this Halomonas high-molecular-weight glycoprotein to emulsify a range of pure hydrocarbon species, as well as refined and crude oils, it shows promise for the bioremediation of contaminated sites.
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Dzevochko, O., M. Podustov, and A. Dzevochko. "SYSTEM ANALYSIS OF THE SULFATION PROCESS IN THE PRODUCTION OF SURFACTANT SUBSTANCES." Integrated Technologies and Energy Saving, no. 4 (December 12, 2022): 23–38. http://dx.doi.org/10.20998/2078-5364.2022.4.03.
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Data on the use of surface-active substances in various areas of Ukrainian industry are given. The rapid development of the production of surface-active substances is shown. The main stages of the production of surface-active substances are given. It is shown that the sulfation stage is the main one, at which high quality indicators of the obtained products are achieved.
The main disadvantages and advantages of sulfating agents in the technology of surface-active substances (surfactants) are given. The characteristics of the equipment and technological schemes of the sulfation process of organic substances are given.
It is claimed that the use of tubular film absorbers with a downward flow of phases is currently the most promising for use in industrial conditions.
Convective diffusion equations for the simplified models of Lewis – Whitman, Levich, Higby, Dankverts are given.
It is proposed to present the process of sulfation in a tubular film absorber with the following stages: the process of mass transfer of gaseous sulfur trioxide to the surface of the interface, the process of absorption of sulfur trioxide by an organic substance with the passage of an exothermic chemical reaction, the process of heat exchange between the liquid phase and the gaseous air flow, the process of heat exchange between the liquid phase and the flow of cooling water. The equation for calculating the mass transfer coefficient is given, which allows obtaining data close to Gutierrez's experimental data. The passage of successive chemical reactions during the absorption of sulfur trioxide by organic raw materials is shown. Kinetic equations and methods of calculating the degree of sulfation and color of the obtained products are given. Basic equations for calculating heat transfer coefficients and heat transfer coefficients are given.
The results of mathematical modeling of the sulfation process in a tubular film absorber are given.
The possibility of achieving high quality indicators of the obtained product is shown: the degree of sulfation is 97,9 %, the color is 1 unit on the iodine scale.
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Cheng, Chien Min, Kai Huang Chen, Yuan Tai Hsieh, and Fuh Cheng Jong. "The Preparation of Flexible Substrate Using BaTiO3/Polymer Composites for Application in High Frequency Devices." Key Engineering Materials 512-515 (June 2012): 1142–45. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.1142.
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BaTiO3/ which has good dielectric properties, they were widely used in ceramic capacitors, thermistors, etc. In this study, BaTiO3/ ceramics prepared by sol-gel powder, then mixed in the organic polymer polyether imide (PEI) and dispersant (surface active agents) and silane coupling agent (Silane Coupling Agent) of the composite material on flexible substrates, And analysis of its properties and electrical properties. Increase by a ceramic powder, to explore the impact of the substrate. In the physical analysis is used XRD, SEM to measure the intensity of crystalline phase and surface uniformity of the electrical measurement using HP4294 measuring dielectric constant and dielectric loss.
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Казаков, Алексей Васильевич, Роман Александрович Емельянов, Дмитрий Викторович Бухтояров, and Денис Владимирович Полтавец. "ANALYSIS OF MODERN TECHNOLOGIES FOR EXTINGUISHING ACTIVE METALS." Pozharnaia bezopasnost`, no. 4(109) (December 16, 2022): 29–35. http://dx.doi.org/10.37657/vniipo.pb.2022.109.4.002.
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Проведен анализ огнетушащих составов, применяемых для тушения активных металлов (пожары класса D). Отмечено, что основные современные средства обеспечения пожаротушения представляют собой галогенсодержащие соли (фториды или хлориды щелочных и щелочно-земельных металлов), препятствующие доступу кислорода без ингибирующего эффекта по отношению к самому горящему металлу. При этом данные солевые композиции не лишены недостатков из-за их высокой гигроскопичности (содержания кристаллизационной воды), что усложняет тушение. Ввиду последнего разработка более эффективных огнетушащих составов для тушения активных металлов является достаточно актуальной и перспективной. Ignition of active metals and their alloys often results in significant material damage. This determines the relevance for development of means to eliminate the possibility of ignition of metals and their alloys in zones of their most likely occurrence - during their melting and refining in metallurgical processes, in the technological processes of their processing and manufacturing of products by enterprises of various industries. For these purposes it is necessary to equip both consumers and special fire departments with highly effective means to ensure fire safety. Burning of active metals is characterized by a very rapid development of the oxidation reaction in the air due to their high reactivity. At the same time, for example, in a D1 class fire (burning of light metals except alkaline), the upper temperature threshold can reach 3000 °C. Alkaline and alkaline-earth metals are able to sustain combustion with limited air oxygen or contact with nitrogen or oxygen-containing substances. Extinguishing metals and their compounds differs from extinguishing fires of other classes. The main extinguishing agent used at protection facilities is a special purpose extinguishing powder. Class D fire extinguishing with a special purpose extinguishing powder consists in creating a protective layer on the burning surface. The use of calming nozzles practically prevents the formation of the air suspension when applying a fire extinguishing agent to burning area. Thus, the principle of extinguishing metals with powder extinguishing agents is to isolate and interrupt the chain reaction of burning. Despite the sufficient effectiveness of the powder compositions used, there was also identified a number of significant drawbacks in the work: a large consumption of extinguishing agent, the difficulty of supplying extinguishing agent to the hearth due to high temperature, the high cost of special extinguishing powders of a new generation, etc. As a matter of fact, it is concluded that the search for more effective means of extinguishing fires of metals and their alloys is relevant and promising, with the absence of these shortcomings.
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Espinoza, Eumarielys, and Luis Isernia. "Role of the lattice-energy from chemical-agents in the activation of highly-condensed carbons." Journal of the Serbian Chemical Society, no. 00 (2021): 27. http://dx.doi.org/10.2298/jsc201211027e.
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Highly condensed carbons from pet-coke were first treated with Na/K hydroxides and carbonates and then with H2SO4. The esterification reaction of palmitic acid reached conversions of up to 97 % on the yielded activated carbons. The results evidence the relationship between the efficacy of Na/K hydroxides and carbonates as treatment agents and their lattice potential energy. Moreover, the analysis of carbonaceous solids confirms that both surface area and acidity are primary factors promoting activity in the esterification reaction. Furthermore, the results do not indicate a direct relationship between the activity and the oxidized species (SOx) arising from the treatment with H2SO4. The relatively low melting and decomposition temperature of Na/K hydroxides can improve their effect on the pet-coke matrix, leading to higher surface areas, acidities, and catalytic activities than treatment with carbonates. This supports an affinity between the carboxyl functions of the fatty acid molecules and the polar and catalytically active centers of the hydroxide-treated solid surface.
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Waglewska, Ewelina, and Urszula Bazylińska. "Biodegradable Amphoteric Surfactants in Titration-Ultrasound Formulation of Oil-in-Water Nanoemulsions: Rational Design, Development, and Kinetic Stability." International Journal of Molecular Sciences 22, no. 21 (October 29, 2021): 11776. http://dx.doi.org/10.3390/ijms222111776.
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Amphoteric amphiphilic compounds, due to their unique properties, may represent a group of safe and biocompatible surface-active agents for effective colloidal stabilization of nanoformulations. For this reason, the aim of this work was to develop and characterize the oil-in-water nanoemulsions based on two betaine-derived surfactants with high biodegradability, i.e., cocamidopropyl betaine and coco-betaine. In the first step, we investigated ternary phase diagrams of surfactant-oil-water systems containing different weight ratios of surfactant and oil, as the betaine-type surfactant entity (S), linoleic acid, or oleic acid as the oil phase (O), and the aqueous phase (W) using the titration-ultrasound approach. All the received nanoemulsion systems were then characterized upon droplets size (dynamic light scattering), surface charge (electrophoretic light scattering), and morphology (transmission electron as well as atomic force microscopy). Thermal and spinning tests revealed the most stable compositions, which were subjected to further kinetic stability analysis, including turbidimetric evaluation. Finally, the backscattering profiles revealed the most promising candidate with a size <200 nm for potential delivery of active agents in the future cosmetic, pharmaceutical, and biomedical applications.
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Baptiste, Keith E., and Max H. Cake. "Lipid Analysis of Lavage Samples from the Equine Guttural Pouch (Auditory Tube Diverticulum)." Annals of Otology, Rhinology & Laryngology 103, no. 5 (May 1994): 383–88. http://dx.doi.org/10.1177/000348949410300508.
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The guttural pouch is a large, air-filled diverticulum of the auditory tube, present in the horse and other species. Lipid analysis of saline lavage from the equine guttural pouch has demonstrated the presence of phospholipids and neutral lipids in amounts that are variable but consistently greater than in any other species described. A stain specific for choline-containing phospholipids has demonstrated the presence of phospholipid-containing vesicles only within the cells of subepithelial, seromucoidlike glands, suggesting that these cells incorporate phospholipids in their secretions. The functional significance of surface-active agents in the guttural pouch may be different from that proposed for other species because of the unique anatomical design and the different proposed functions of the guttural pouch.
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Annisa, Mutiara, Puteri Aulia Rizqi Kanina, Nur Liyana Binti Hamid, and Archadian Nuryanti. "<strong>Effectiveness of green tea, bay leaf, and lime peel extracts as toothpastes active agents for extrinsic stain removal on teeth, artificial teeth, and denture base</strong>." Padjadjaran Journal of Dentistry 34, no. 1 (April 9, 2022): 47. http://dx.doi.org/10.24198/pjd.vol34no1.32236.
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Introduction: Tea consumption causes extrinsic stain formation on teeth and denture surfaces, affecting personal appearance. Herbal plants extract such as green tea, bay leaf, and lime peel are potentially active agents for extrinsic stain removal. This study aimed to analyse the effectiveness of green tea, bay leaf, and lime peel extracts as toothpaste active agents for extrinsic stain removal on teeth, artificial teeth, and denture base. Methods: Twenty-five post-extracted human permanent central incisors, 25 artificial teeth, and 25 heat polymerised acrylic resin denture base (20x20x10mm) were divided into three treatment groups and two control groups. Pictures of all specimens were taken before and after stain induction and after brushing. All specimens were immersed in a tea solution made from 2 grams of tea and 100ml of 100°C boiled water to induce extrinsic stain. The immersion process was repeated every 24 hours for seven days. All specimens were then brushed using an automatic toothbrushing machine for 70 seconds on each surface, 200 grams loads, and five speeds/second. Toothpaste used for brushing were three different active agent toothpaste (treatment groups), no active agent toothpaste, and commercial whitening (control groups). Colour index analysis of the specimen pictures computerised by CIELAB method. The data were analysed by one-way ANOVA (α=0.05). Results: Green tea, bay leaf, and lime peel extract toothpaste and positive control had higher L-values of extrinsic stain removal than essential toothpaste on all specimens. There was a significant difference between green tea, bay leaf, and lime peel extract toothpaste and negative control toothpaste (p<0.05), while no significant difference was found when compared to the positive control toothpaste (p>0.05). Conclusion: Green tea, bay leaf, and lime peel extract toothpaste are effective as extrinsic stain removal on teeth and acrylic resin denture base because of abrasive materials that work together with the active agents such as epigallocatechin-3-gallate (EGCG) in green tea, eugenol in bay leaf, and naringin in lime peel.
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Weisheitelova, Marketa, Karel Klouda, and Stanislav Lasek. "Effects of Passive and Active Decontamination on Metal Materials Contaminated by Sulphur Mustard (Yperite)." Communications - Scientific letters of the University of Zilina 21, no. 2 (May 24, 2019): 37–43. http://dx.doi.org/10.26552/com.c.2019.2.37-43.
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This paper reports the results of the experimentally determined effects of decontaminating agents on metal surfaces resulting from passive and active decontamination after sulphur mustard (Yperite) contamination. The paper includes an analysis of the experimentally obtained results for each metal (Zinc, Nickel, Aluminium, Brass, Steel, Copper).
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Fernando, Angelo Ransirimal, and Byron Kratochvil. "Internal standards in differential pulse anodic stripping voltammetry." Canadian Journal of Chemistry 69, no. 4 (April 1, 1991): 755–58. http://dx.doi.org/10.1139/v91-111.
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The use of lead and cadmium as internal standards for each other in anodic stripping analysis was investigated. Although accuracy was not affected, precision was significantly improved. The surface active agents Triton-X 100 and starch affected the sensitivity of the anodic stripping procedure for lead and cadmium, leading to error if a calibration curve is used. Data for application of the procedure to the analysis of the marine biological reference material LUTS-1 and soil reference materials SO-2, SO-3, and SO-4 are provided. Key words: internal standard, anodic stripping voltammetry, calibration curve, standard addition, lead determination, cadmium determination.
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Furtat, Iryna, Oleksii Nechypurenko, Polina Vakuliuk, Maryna Vortman, and Valerii Shevchenko. "Antimicrobial activity of traditional and newly synthetized surface-active agents as a basis for the creation of new disinfectants." NaUKMA Research Papers. Biology and Ecology 5 (September 19, 2022): 25–32. http://dx.doi.org/10.18523/2617-4529.2022.5.25-32.
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Aim. The main goal of the study was to investigate the antibacterial and fungicidal properties of the traditional and newly synthesized surfactants of different classes, compare the analysis of their antimicrobial activity and find out the prospects for further use for the creation of disinfectants. Methods. The biocidal activity of the studied cationic, anionic and nonionic surfactants was determined in relation to representatives of the species Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, as well as fungi Candida albicans. The detection of antibacterial and fungicidal effect and determination of minimum inhibitory concentrations (MIC) was carried out by cultivation of the test cultures of microorganisms in Nutrient Broth (NB, Himedia, India) for 24–48 hours at 37 °С in the presence of different concentrations of experimental surfactants (1000–0.1 ppm). The number of cells that remained viable after exposure to surfactants was determined by optical density in McFarland units, which were then converted to the number of cells in 1 ml using the standard McFarland scale. Results. The newly synthesized guanidine-containing oligomer at concentrations of 1000 and 100 ppm inhibited the growth of all test cultures without exception by 100 %. The biocidal effect on the representatives of various taxonomic groups of microorganisms differed in its effectiveness for various anionic surfactants (trilon B, surfactant 2 and surfactant 3) even at the highest concentration of 1000 ppm. In particular, only trilon B completely inhibited the growth of all test cultures. However, at the concentrations indicated above, the examined cationic (surfactant 1 and triethanolamine) and nonionic (OP-10 and triton X-100) exhibited a rather low antimicrobial activity. Conclusions. The results obtained indicate that the guanidine-containing oligomer exhibited the highest antimicrobial activity among the investigated surfactants. Therefore, it can be considered a promising surfactant for further use in the creation of broad-spectrum antimicrobial agents. Enhancement of the biocidal effect of newly created disinfectants can be implemented by introducing the studied anionic and nonionic detergents, and glutaraldehyde can be used to stabilize them or enhance their antimicrobial activity. Instead, the application of cationic surfactants used in the work is impractical.
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Habib, Salma, Marian Lehocky, Daniela Vesela, Petr Humpolíček, Igor Krupa, and Anton Popelka. "Preparation of Progressive Antibacterial LDPE Surface via Active Biomolecule Deposition Approach." Polymers 11, no. 10 (October 17, 2019): 1704. http://dx.doi.org/10.3390/polym11101704.
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The use of polymers in all aspects of daily life is increasing considerably, so there is high demand for polymers with specific properties. Polymers with antibacterial properties are highly needed in the food and medical industries. Low-density polyethylene (LDPE) is widely used in various industries, especially in food packaging, because it has suitable mechanical and safety properties. Nevertheless, the hydrophobicity of its surface makes it vulnerable to microbial attack and culturing. To enhance antimicrobial activity, a progressive surface modification of LDPE using the antimicrobial agent grafting process was applied. LDPE was first exposed to nonthermal radio-frequency (RF) plasma treatment to activate its surface. This led to the creation of reactive species on the LDPE surface, resulting in the ability to graft antibacterial agents, such as ascorbic acid (ASA), commonly known as vitamin C. ASA is a well-known antioxidant that is used as a food preservative, is essential to biological systems, and is found to be reactive against a number of microorganisms and bacteria. The antimicrobial effect of grafted LDPE with ASA was tested against two strong kinds of bacteria, namely, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), with positive results. Surface analyses were performed thoroughly using contact angle measurements and peel tests to measure the wettability or surface free energy and adhesion properties after each modification step. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the surface morphology or topography changes of LDPE caused by plasma treatment and ASA grafting. Surface chemistry was studied by measuring the functional groups and elements introduced to the surface after plasma treatment and ASA grafting, using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). These results showed wettability, adhesion, and roughness changes in the LDPE surface after plasma treatment, as well as after ASA grafting. This is a positive indicator of the ability of ASA to be grafted onto polymeric materials using plasma pretreatment, resulting in enhanced antibacterial activity.
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Walzer, P. D., J. Runck, S. Orr, J. Foy, P. Steele, and M. White. "Clinically used antimicrobial drugs against experimental pneumocystosis, singly and in combination: analysis of drug interactions and efficacies." Antimicrobial Agents and Chemotherapy 41, no. 2 (February 1997): 242–50. http://dx.doi.org/10.1128/aac.41.2.242.
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We analyzed single drugs and combinations of drugs used clinically in the treatment of opportunistic infections and other conditions for their activities against Pneumocystis carinii pneumonia in immunosuppressed rats. When they were used alone, atovaquone, rifabutin, and dapsone were more active than clarithromycin or trimethoprim. Drug combinations were evaluated for synergistic activity by an analysis of variance model for two-way factorial experiments and a response surface model. Atovaquone combined with trimethoprim trimethoprim and some combinations of dapsone and clarithromycin was synergistic; however, the activities of combinations of atovaquone and rifabutin, atovaquone and clarithromycin, and atovaquone and dapsone were simply additive. Lovastatin, which inhibits 3-hydroxy-methylglutaryl coenzyme A reductase, was inactive whether it was used alone or in combination with other agents. None of the synergistic drug combinations was as effective as trimethoprim-sulfamethoxazole. We conclude that the rat model can be used to test combinations of anti-P. carinii agents for synergistic activity by well-established statistical techniques. While some combinations of clinically used antimicrobial drugs have enhanced anti-P. carinii activity, further studies are needed before clinical trials can be contemplated.
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Leong, Chean Ring, Nurul Shahida Daud, Woei Yenn Tong, See Yuan Cheng, Wen Nee Tan, Nurhanis Syafiqah Hamin, and Khairul Faizal Pa'ee. "Gelatine Film Incorporated with Clitoria ternatea-Derived Anthocyanin Microcapsules, A Food Packaging Material Effective Against Foodborne Pathogens." Food Technology and Biotechnology 59, no. 4 (September 30, 2021): 422–31. http://dx.doi.org/10.17113/ftb.59.04.21.7069.
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Research background. Microbial contamination of food products is one of the significant causes of food spoilage and foodborne illnesses. The use of active packaging films incorporated with antimicrobial agents can be a measure to improve food quality and extend shelf life. Nevertheless, antimicrobial agents such as silver, copper, titanium and zinc in the packaging films have raised concerns among consumers due to toxicity issues. Experimental approach. The current study aims to develop biodegradable gelatine- based edible films incorporated with microcapsules of Clitoria ternatea-derived anthocyanins as a natural antimicrobial agent. The impact of incorporation of microcapsules with anthocyanins on the morphology, thermal, mechanical, water vapour barrier and physicochemical properties of the gelatine films was evaluated in this study. The effectiveness of the developed films against foodborne pathogens and their application for perishable food protection were also investigated. Results and conclusions. The results show that incorporating anthocyanin microcapsules enhances the gelatine film physical and mechanical properties by increasing the thickness, tensile strength, Young’s modulus and elongation at break of the films. Scanning electronic microscopy analysis revealed that the film surface morphology with anthocyanin microcapsules had a homogeneous and smooth surface texture compared to the control. The thermogravimetric analysis also showed a slight improvement in the thermal properties of the developed films. Agar well diffusion assay revealed that the developed films exhibit significant inhibition against a broad-spectrum of bacteria. Furthermore, the films composed of gelatine with anthocyanin microcapsules significantly reduced the total viable count of microorganisms in the bean curd during storage for 12 days compared with the control films. Novelty and scientific contribution. Increasing global awareness of healthy and safe food with minimal synthetic ingredients as preservatives has sparked the search for the use of antimicrobial agents of natural origins in active food packaging material. In this study, a safe and effective active packaging film was developed using an environmentally friendly biopolymer, gelatine film incorporated with microcapsules of Clitoria ternatea-derived anthocyanins as a natural antimicrobial agent. This study demonstrated that such a method is not only able to improve the film physical properties but can also significantly prolong the shelf life of food products by protecting them from microbial spoilage.
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Rahman, Kazi Hasibur, and Asit Kumar Kar. "Hydroxylation-induced defect states and formation of a bidentate acetate adstructure of TiO2 catalysts with acetic acid variation for catalytic application." Semiconductor Science and Technology 37, no. 4 (February 24, 2022): 045008. http://dx.doi.org/10.1088/1361-6641/ac48dc.
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Abstract TiO2 is considered a promising candidate for catalysis applications. The addition of acetic acid and its variation creates a strong bond with oxide surfaces, which generates various oxidizing agents. X-ray diffraction analysis of the prepared TiO2 nanoparticles reveals their semicrystalline nature. The results show that holes are captured by the surface and subsurface, producing ≡ T i IV − O H . , ≡ T i IV − O . − − T i IV ≡ and the reducing agent = T i III − , which act as active oxidizers during photocatalysis, thus confirming the occurrence of an OH radical via an advanced oxidation process. Increasing the acetic acid amount leads to disordered structural defects below the conduction band (CB). X-ray photoelectron spectroscopy analysis shows the induction of hydroxylation of surface defects, such as Ti–OH. The results indicate that an oxygen vacancy is favourable due to a large number of surface defects. Detailed discussion of the energy band structure with the concept of a valence band (VB) and a CB maximum is implemented. The electron-withdrawing carboxylic group can affect oxygen vacancies and acetate ligands on the photocatalyst surface. The formation of a bidentate acetate adstructure with a lower acetic acid concentration leads to an explanation for higher visible-light-driven methylene blue degradation. The mechanism for the formation of an additional Ti–O–Ti bond by a condensation process is also illustrated elaborately. Theoretical calculations of the potentials of the VB and CB show the effects of active sites on degradation and can be associated with redox reactions for water splitting abilities. A possible model of sensitized photocatalysis for hydrogen production with hydrogen and oxygen evolution sites is also proposed in this article. Thus, TiO2 nanoparticles with acetic acid variation are promising sources for photocatalytic/catalytic applications.
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Matmin, Juan, Irwan Affendi, Salizatul Ibrahim, and Salasiah Endud. "Additive-Free Rice Starch-Assisted Synthesis of Spherical Nanostructured Hematite for Degradation of Dye Contaminant." Nanomaterials 8, no. 9 (September 8, 2018): 702. http://dx.doi.org/10.3390/nano8090702.
Full textAbstract:
Nanostructured hematite materials for advanced applications are conventionally prepared with the presence of additives, tainting its purity with remnants of copolymer surfactants, active chelating molecules, stabilizing agents, or co-precipitating salts. Thus, preparing nanostructured hematite via additive-free and green synthesis methods remains a huge hurdle. This study presents an environmentally friendly and facile synthesis of spherical nanostructured hematite (Sp-HNP) using rice starch-assisted synthesis. The physicochemical properties of the Sp-HNP were investigated by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DR UV-Vis), and nitrogen adsorption–desorption analysis. The Sp-HNP showed a well-crystallized structure of pure rhombohedral phase, having a spherical-shaped morphology from 24 to 48 nm, and a surface area of 20.04 m2/g. Moreover, the Sp-HNP exhibited enhanced photocatalytic degradation of methylene blue dye, owing to the large surface-to-volume ratio. The current work has provided a sustainable synthesis route to produce spherical nanostructured hematite without the use of any hazardous agents or toxic additives, in agreement with the principles of green chemistry for the degradation of dye contaminant.
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Boyer, Ivan, Christina L. Burnett, Wilma F. Bergfeld, Donald V. Belsito, Ronald A. Hill, Curtis D. Klaassen, Daniel C. Liebler, et al. "Safety Assessment of PEGs Cocamine and Related Ingredients as Used in Cosmetics." International Journal of Toxicology 37, no. 2_suppl (September 2018): 10S—60S. http://dx.doi.org/10.1177/1091581818794417.
Full textAbstract:
The Cosmetic Ingredient Review Expert Panel assessed the safety of 47 polyethylene glycols (PEGs) cocamine and related ingredients, which are reported to function mostly as surfactants and antistatic agents. The Panel reviewed the relevant data and developed a framework to satisfy previously identified data deficiencies for this group of materials as well as extend the scope of related materials covered by the analysis. The irritation potential of these ingredients is consistent with the surface active properties that are characteristic of surfactants. The Panel concluded that the PEGs cocamine and related ingredients were safe as ingredients in cosmetic formulations in the current practices of use and concentration when formulated to be nonirritating.
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CHACÓN, C., J. A. HENAO, J. JAMALIS, P. RIVAS, W. VELÁSQUEZ, and G. E. DELGADO. "SYNTHESIS, CRYSTAL STRUCTURE AND HIRSHFELD SURFACE ANALYSIS OF 1-ACETYL-5-(2-METHYLPROPYL)-2-THIOXO-IMIDAZOLIDIN- 4-ONE." Periódico Tchê Química 15, no. 29 (January 20, 2018): 292–99. http://dx.doi.org/10.52571/ptq.v15.n29.2018.292_periodico29_pgs_292_299.pdf.
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The hydantoin and thiohydantoin heterocycles are present in a wide range of biologically active compounds including therapeutic drugs for the treatment of seizures and anti-tumor compounds. Thiohydantoins, have also been used as anti-convulsant agents and are present in fungicides, herbicides and natural products. However, the principal current interest comes from the application of thiohydantoins for the treatment of prostate cancers. Structural characterization of hydantoin and thiohydantoin are important to comprehend their effect mechanisms because of their considerable biological effects. In this work a thiohydantoin derivative, 1-acetyl-5-(2-methylpropyl)-2-thioxo-imidazolidin-4-one (I), has been obtained by the reaction of 2-amino-4-methylpentanoic acid with KSCN in acetic anhydride-acetic acid mixture. The heterocyclic compound was characterized by FTIR, NMR, powder and single-crystal X-ray diffraction analysis. This compound crystallizes in the triclinic system, space group P-1 (Nº2), Z=4, with two independent molecules in the unit asymmetric. The thiohydantoin (I) forms one-dimensional hydrogen bonded chains, via a single hydrogen bond between the carbonyl oxygens and the amine ring N3 position, that run along [100] direction, with graphset motif C(6). The nature of intermolecular interactions has been analyzed through Hirshfeld surfaces and 2D fingerprint plots.
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Pacholak, Amanda, Natalia Burlaga, and Ewa Kaczorek. "Evaluating the Effect of Azole Antifungal Agents on the Stress Response and Nanomechanical Surface Properties of Ochrobactrum anthropi Aspcl2.2." Molecules 25, no. 15 (July 23, 2020): 3348. http://dx.doi.org/10.3390/molecules25153348.
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Azole antifungal molecules are broadly used as active ingredients in various products, such as pharmaceuticals and pesticides. This promotes their release into the natural environment. The detailed mechanism of their influence on the biotic components of natural ecosystems remains unexplored. Our research aimed to examine the response of Ochrobactrum anthropi AspCl2.2 to the presence of four azole antifungal agents (clotrimazole, fluconazole, climbazole, epoxiconazole). The experiments performed include analysis of the cell metabolic activity, cell membrane permeability, total glutathione level and activity of glutathione S-transferases. These studies allowed for the evaluation of the cells’ oxidative stress response to the presence of azole antifungals. Moreover, changes in the nanomechanical surface properties, including adhesive and elastic features of the cells, were investigated using atomic force microscopy (AFM) and spectrophotometric methods. The results indicate that the azoles promote bacterial oxidative stress. The strongest differences were noted for the cells cultivated with fluconazole. The least toxic effect has been attributed to climbazole. AFM observations unraveled molecular details of bacterial cell texture, structure and surface nanomechanical properties. Antifungals promote the nanoscale modification of the bacterial cell wall. The results presented provided a significant insight into the strategies used by environmental bacterial cells to survive exposures to toxic azole antifungal agents.
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Rima, Maya, Asma Chbani, Christine Roques, and Fatima El Garah. "Seaweed Extracts as an Effective Gateway in the Search for Novel Antibiofilm Agents against Staphylococcus aureus." Plants 11, no. 17 (August 31, 2022): 2285. http://dx.doi.org/10.3390/plants11172285.
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Treatment of biofilm-associated infections has become a major challenge in biomedical and clinical fields due to the failure of conventional treatments in controlling this highly complex and tolerant structure. Therefore, the search for novel antibiofilm agents with increased efficacy as those provided by natural products, presents an urgent need. The aim of this study was to explore extracts derived from three algae (green Ulva lactuca, brown Stypocaulon scoparium, red Pterocladiella capillacea) for their potential antibiofilm activity against Staphylococcus aureus, bacterium responsible for several acute and chronic infections. Seaweed extracts were prepared by successive maceration in various solvents (cyclohexane (CH), dichloromethane (DCM), ethyl acetate (EA), and methanol (MeOH)). The ability of the different extracts to inhibit S. aureus biofilm formation was assessed using colony-forming unit (CFU) counts method supported by epifluorescence microscopic analysis. Effects of active extracts on the biofilm growth cycle, as well as on S. aureus surface hydrophobicity were evaluated. Results revealed the ability of four extracts to significantly inhibit S. aureus biofilm formation. These findings were supported by microscopy analyses. The gradual increase in the number of adherent bacteria when the selected extracts were added at various times (t0, t2h, t4h, t6h, and t24h) revealed their potential effect on the initial adhesion and proliferation stages of S. aureus biofilm development. Interestingly, a significant reduction in the surface hydrophobicity of S. aureus treated with dichloromethane (DCM) extract derived from U. lactuca was demonstrated. These findings present new insights into the exploration of seaweeds as a valuable source of antibiofilm agents with preventive effect by inhibiting and/or delaying biofilm formation.
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J.Hasson, Kahtan. "Enhancement of Atorvastatin Tablet Dissolution Using Acid Medium." Iraqi Journal of Pharmaceutical Sciences ( P-ISSN: 1683 - 3597 , E-ISSN : 2521 - 3512) 19, no. 1 (March 30, 2017): 82–85. http://dx.doi.org/10.31351/vol19iss1pp82-85.
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In this study some generic commercial products of Atorvastatin tablets were evaluated by dissolution test in acid medium by comparing with that of parent drug Lipitor of Pfizer Company. Some of solubilizing agents were studied in formulation of Atorvastatin tablet including; surface active agent and PEG 6000 .The most effective factor was the use of PEG6000 in formulation of Atorvastatin tablet which improved the dissolution and the results of dissolution profile of formulated tablet in this work was bioequivalent to that of Lipitor .The quantitative analysis of this work was performed by using reversed phase liquid chromatography and a proper mixture of mobile phase which give a retention time for Atorvastatin about 6 minutes .
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Zhang, Li Ping, Lei Ke, Miao Miao Xie, Yuan Jie Guo, Qian Yu Hu, and Xu Wen He. "Titanium Positive Plate Manufacturing Process and Denitrification Mechanism." Advanced Materials Research 148-149 (October 2010): 668–73. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.668.
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Prepared a electrode with high concentration and strong active oxidizing property which used titanium as anode’s substrate material, used gradient method the anode surface was coated with a definite ratio RuO2、TiO2、IrO2、SnO2、Ga and Ce in order to extend the operational life span. Use scanning electron microscope to present the surface property, the result shows that the surface coat of self-made titanium positive plate is densification and well-distributed which has good catalytic activity and reaction stability, meanwhile the surface coated with metallic oxides has less and short cracks which can extend the useful life. Through the electrochemistry property detection by electrochemistry workstation, Tafel curve shows that the chlorine precipitation potential is 1.41V which is just a little higher than the standard potential 1.36v of Cl- reacting to form Cl2, meanwhile lower than the oxygen precipitation potential, these shows that the plate has good electro-catalysis property and selectivity. The self-made experimental setup includes four parts as direct supply, reactive tank, electrode, collecting bottle. Prepared solution with deionized water and analytical pure agents with NH4Cl and NaCl, with draining water method collecting the electro-catalysis gas and gas chromatographic analysis shows the main component includes N2 62.73%, O2 21.47%，H2 13.95%，Cl2 1.85%, meanwhile analysis the trends of nitrogen forms concentration, chloridion concentration and pH by electrolysis time, concluding that the indirect oxidation is dominant process during electrochemistry, active substrate OCl- is the principal oxidation. The electrolyte pH keeps range between 7.5 and 9.5 which is favorable to free ammonia forming that can be directly electrochemical oxidized, meanwhile is disadvantage of free chlorine forming that can keep cyclic utilization in solution.
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Mahony, Helen, Ambuj Kumar, Rahul Mhaskar, Branko Miladinovic, Keith Wheatley, and Benjamin Djulbegovic. "Maintenance Therapies for Multiple Myeloma (MM): A Network Meta-Analysis." Blood 120, no. 21 (November 16, 2012): 236. http://dx.doi.org/10.1182/blood.v120.21.236.236.
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Abstract Abstract 236 Background: There is little consensus on which maintenance therapy clinicians should choose for their patients. Since 1999, the three novel agents of bortezomib, lenalidomide, and thalidomide have been approved for use among patients with MM. These agents have been increasingly used as maintenance therapy. To date, only two randomized controlled trials of maintenance therapy have examined the efficacy of these novel agents head-to-head. Here, we conduct a network meta-analysis of bortezomib, lenalidomide, and thalidomide to determine which of these novel agents could potentially increase overall survival (OS) and progression-free survival (PFS). Methods: A comprehensive literature search of MEDLINE (PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL), and meetings abstracts from American Society of Hematology, American Society of Clinical Oncology, European Society for Medical Oncology and European Hematology Association was undertaken to identify all phase III randomized controlled trials (RCTs) of maintenance therapy published until July 2012. We applied the Bayesian mixed treatment comparison (MTC) method under the random-effects model. The indirect comparisons were constructed from trials that have one treatment in common. For each included RCT, we calculated the hazard ratio (HR) and its corresponding standard error and used this to calculate the indirect estimates of HR and corresponding credible intervals (CrI). We also ranked the treatments according to the probability of best treatment and calculated the surface underneath the cumulative ranking curve (SUCRA). All analyses were conducted in WinBUGS 1.4.3 and Stata 11.2. Results: The network, number of trials for each comparison, and number of patients enrolled is shown in Figure 1. The network for OS was based on 12 RCTs enrolling 5542 patients and the network for PFS was constructed from 13 RCTs and 5784 patients. The MTC networks were consistent for both OS and PFS. For both OS and PFS, two comparisons were produced (Figure 2). For OS, the analysis showed that none of the treatments were superior. For PFS, lenalidomide was superior to thalidomide (HR = 0.58, 95% CrI [0.37, 0.94]). The estimates of SUCRA and rank probabilities (Figure 3) suggested that for OS bortezomib was best followed by lenalidomide and thalidomide. For PFS, lenalidomide was best followed by bortezomib and thalidomide. Conclusion: Using the MTC method, we found no evidence that any of the novel agents are superior to one another in terms of OS. Lenalidomide was the only novel agent which was superior to another active therapy (thalidomide). While these results provide preliminary evidence to which novel agent may be more beneficial as maintenance therapy, definitive conclusions cannot be reached until large, well designed RCTs evaluating these therapies head-to-head are conducted. Disclosures: No relevant conflicts of interest to declare.
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Sharma, Deepansh, Baljeet Singh Saharan, Nikhil Chauhan, Anshul Bansal, and Suresh Procha. "Production and Structural Characterization ofLactobacillus helveticusDerived Biosurfactant." Scientific World Journal 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/493548.
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A probiotic strain oflactobacilliwas isolated from traditional soft Churpi cheese of Yak milk and found positive for biosurfactant production.Lactobacillireduced the surface tension of phosphate buffer saline (PBS) from 72.0 to 39.5 mNm−1pH 7.2 and its critical micelle concentration (CMC) was found to be 2.5 mg mL−1. Low cost production ofLactobacilliderived biosurfactant was carried out at lab scale fermenter which yields 0.8 mg mL−1biosurfactant. The biosurfactant was found least phytotoxic and cytotoxic as compared to the rhamnolipid and sodium dodecyl sulphate (SDS) at different concentration. Structural attributes of biosurfactant were determined by FTIR, NMR (1H and13C), UPLC-MS, and fatty acid analysis by GCMS which confirmed the presence of glycolipid type of biosurfactant closely similar to xylolipids. Biosurfactant is mainly constituted by lipid and sugar fractions. The present study outcomes provide valuable information on structural characterization of the biosurfactant produced byL. helveticusMRTL91. These findings are encouraging for the application ofLactobacilliderived biosurfactant as nontoxic surface active agents in the emerging field of biomedical applications.
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Pini, N. I. P., D. A. N. L. Lima, J. R. Lovadino, C. Ganss, and N. Schlueter. "In vitro Efficacy of Experimental Chitosan-Containing Solutions as Anti-Erosive Agents in Enamel." Caries Research 50, no. 3 (2016): 337–45. http://dx.doi.org/10.1159/000445758.
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The present study evaluated the effect of chitosans with different viscosities, dissolved in an AmF/SnCl2 solution, against erosion or erosion/abrasion. A total of 192 specimens were assigned to 2 × 6 groups (n = 16 specimens each): negative control, 4 chitosan solutions (groups Ch50, Ch500, Ch1000, and Ch2000, with viscosity of 50, 500, 1,000, or 2,000 mPas, respectively, 0.5% chitosan, 500 ppm F-, 800 ppm Sn2+, pH 4.4), and positive control (500 ppm F-, 800 ppm Sn2+, pH 4.3). One half of the groups was demineralized (experiment 1, E1; 10 days, 6 × 2 min/day, 0.5% citric acid, pH 2.8) and exposed to solutions (2 × 2 min/day); the other half was additionally brushed (15 s, 200 g) with non-fluoridated toothpaste before solution immersion (experiment 2, E2). Treatment effects were investigated by profilometry, energy-dispersive X-ray spectroscopy and scanning electron microscopy (SEM). In E1, all the chitosan-containing solutions reduced enamel loss by 77-80%, to the same extent as the positive control, except for Ch2000 (p ≤ 0.05), which completely inhibited tissue loss by the formation of precipitates. In E2, Ch50 and Ch500 showed best performance, with approximately 60% reduction of tissue loss compared to the negative control group (p ≤ 0.05 compared to other groups). SEM analysis showed differences between negative control and the other groups but only minor differences amongst the groups treated with active agents. In both E1 and E2, treatment with active agents resulted in surface enrichment of carbon and tin compared to negative control (p ≤ 0.001); brushing removed parts of carbon and tin (p ≤ 0.001). Chitosan shows different properties under erosive and erosive/abrasive conditions. Under erosive conditions high viscosity might be helpful, whereas lower viscosity seems to be more effective in cases of chemo-mechanical challenges.
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Anthoney, Daud, Shahreen Zahid, Hina Khalid, Zohaib Khurshid, Asma Tufail Shah, Aqif Anwar Chaudhry, and Abdul Samad Khan. "Effectiveness of Thymoquinone and Fluoridated Bioactive Glass/Nano-Oxide Contained Dentifrices on Abrasion and Dentine Tubules Occlusion: An Ex Vivo Study." European Journal of Dentistry 14, no. 01 (February 2020): 045–54. http://dx.doi.org/10.1055/s-0040-1703418.
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Abstract Objectives Dentin hypersensitivity (DH) is mainly due to the loss and replenishment of minerals from tooth structure, where the lost minerals can be rehabilitated with a biomimetic approach. The objectives were to determine the relative dentin abrasivity (RDA) of experimental (EXT) dentifrices and to determine the efficacy to occlude dentinal tubules. Materials and Methods Experimental dentifrices contained nano-fluoridated bioactive glass (n-FBG: 1.5 wt.% [EXT-A], 2.5 wt.% [EXT-B], and 3.5 wt.% [EXT-C]), nano-zinc oxide (n-ZnO), and thymoquinone as active agents. Bovine dentin blocks were subjected to brushing treatments as per groups, that is, distilled water; commercial dentifrice (control, CT); EXT toothpastes; and EXT-D without active agents. Samples were tested for three-dimensional (3D) abrasion analysis according to ISO-11609:2010 (International Organization for Standardization [ISO]). The roughness average (Ra), RDA, surface topography, and elemental compositions were investigated. Statistical Analysis One-way analysis of variance (ANOVA) with post-hoc Tukey’s and Tamhane’s test was performed for characterizations using Statistical Package for the Social Sciences (SPSS) version 21. The result was considered significant with p-value ≤ 0.05. Results Comparisons of Ra differed significantly between all groups with p < 0.05 except CT and EXT-A. The RDA values of EXT-A, EXT-B, and EXT-C were calculated as 74.04, 84.26, and 116.24, respectively, which were well within the acceptable limit set by international standards. All n-FBG containing dentifrices demonstrated uniform occlusion of dentinal tubules; however, highly concentrated EXT dentifrices showed more occlusion. Conclusions Acceptable range of RDA and superior occlusion of tubules by novel dentifrices suggest that it may be recommended for treating DH.
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Ismailov, U., and A. Zurdinov. "Pharmacoepidemiological Analysis of the Use of Oral Hypoglycemic Preparations: Factors Affecting the Effectiveness of Pharmacotherapy for Type 2 Diabetes Mellitus." Bulletin of Science and Practice 7, no. 10 (October 15, 2021): 214–24. http://dx.doi.org/10.33619/2414-2948/71/23.
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As a result of the pharmacoepidemiological study, factors have been established that make it possible to increase the effectiveness of hypoglycemic therapy and the compliance of patients with diabetes mellitus in Kyrgyzstan. The structure of the prescribed oral hypoglycemic agents was investigated; the assessment, according to the results of the questionnaire of patients, was given of the effectiveness of the hypoglycemic therapy they received, as well as the level of its compliance with modern medical guidelines for the diagnosis and treatment of diabetes. At the time of filling out the questionnaire, only 44% of respondents had a target fasting glucose level (≤7 mmol/l). According to the data obtained, it can be concluded that in real clinical practice, the effectiveness of diabetes treatment remains low. We have obtained data that 47.8% of patients with diabetes are not adherent to treatment, which may also contribute to a rather low percentage of patients among the respondents who have reached the target blood glucose level. As for the use of drugs, the analysis of the data showed that the majority of patients (62.81%) receive monotherapy with oral hypoglycemic agents. According to the analysis, metformin is the most commonly used drug among the oral hypoglycemic agents. It is accepted by 60.1% of the respondents. Most diabetic patients spend 1000 som or more per month on oral hypoglycemic agents. Taking into account the cost of living in the country, it can be concluded that the acquisition of oral hypoglycemic agents significantly affects the budget of citizens and that there are problems with the economic availability of oral hypoglycemic agents. The results of our research indicate the insufficient effectiveness of the treatment and prophylactic measures for type 2 diabetes in our country, requiring more active work in this direction. The work was carried out in the design of a simple one-step prospective descriptive epidemiological study within the framework of a pharmacoepidemiological study.
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Shang, Xiaoran, and Daniel C. Nelson. "Contributions of Net Charge on the PlyC Endolysin CHAP Domain." Antibiotics 8, no. 2 (May 28, 2019): 70. http://dx.doi.org/10.3390/antibiotics8020070.
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Bacteriophage endolysins, enzymes that degrade the bacterial peptidoglycan (PG), have gained an increasing interest as alternative antimicrobial agents, due to their ability to kill antibiotic resistant pathogens efficiently when applied externally as purified proteins. Typical endolysins derived from bacteriophage that infect Gram-positive hosts consist of an N-terminal enzymatically-active domain (EAD) that cleaves covalent bonds in the PG, and a C-terminal cell-binding domain (CBD) that recognizes specific ligands on the surface of the PG. Although CBDs are usually essential for the EADs to access the PG substrate, some EADs possess activity in the absence of CBDs, and a few even display better activity profiles or an extended host spectrum than the full-length endolysin. A current hypothesis suggests a net positive charge on the EAD enables it to reach the negatively charged bacterial surface via ionic interactions in the absence of a CBD. Here, we used the PlyC CHAP domain as a model EAD to further test the hypothesis. We mutated negatively charged surface amino acids of the CHAP domain that are not involved in structured regions to neutral or positively charged amino acids in order to increase the net charge from -3 to a range from +1 to +7. The seven mutant candidates were successfully expressed and purified as soluble proteins. Contrary to the current hypothesis, none of the mutants were more active than wild-type CHAP. Analysis of electrostatic surface potential implies that the surface charge distribution may affect the activity of a positively charged EAD. Thus, we suggest that while charge should continue to be considered for future engineering efforts, it should not be the sole focus of such engineering efforts.
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Aribi Al-Zoobaee, Farah Wasim, Loo Yee Shen, Sajesh K. Veettil, Divya Gopinath, Mari Kannan Maharajan, and Rohit Kunnath Menon. "Antiviral Agents for the Prevention and Treatment of Herpes Simplex Virus Type-1 Infection in Clinical Oncology: A Network Meta-Analysis." International Journal of Environmental Research and Public Health 17, no. 23 (November 30, 2020): 8891. http://dx.doi.org/10.3390/ijerph17238891.
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Cancer therapy may be complicated and compromised by viral infections, including oral herpes simplex virus (HSV) infection. This network meta-analysis aimed to identify the best antiviral agent to prevent or treat oral HSV infection in patients being treated for cancer. A search was conducted for trials published since inception until the 10th of May 2020 in MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. A network meta-analysis was performed on the data from randomized controlled trials that assessed antiviral agents for preventive or therapeutic activity vs. placebo, no treatment or any other active intervention in patients being treated for cancer. The agents were ranked according to their effectiveness in the prevention of oral HSV using surface under the cumulative ranking (SUCRA). Grading of Recommendations, Assessment, Development and Evaluations (GRADE) was used to assess the certainty of the evidence. In total, 16 articles were included. The pooled relative risk (RR) to develop oral HSV infection in the acyclovir group was 0.17 (95% CI: 0.10, 0.30), compared to 0.22 (95% CI: 0.06, 0.77) in the valacyclovir group. Acyclovir ranked highest for the prevention of oral HSV followed by valacyclovir. Subgroup analysis with different acyclovir regimens revealed that the best regimens in terms of HSV-1 prevention were 750 mg/m2 acyclovir administered intravenously followed by 1600 mg per day orally. Acyclovir (250 mg/m2 per day) administered intravenously was the least effective against the prevention of oral HSV.
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Ben Osman, Yasmine, Samar Hajjar-Garreau, Dominique Berling, and Hanene Akrout. "Elaboration of Highly Modified Stainless Steel/Lead Dioxide Anodes for Enhanced Electrochemical Degradation of Ampicillin in Water." Separations 10, no. 1 (December 22, 2022): 5. http://dx.doi.org/10.3390/separations10010005.
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Lead dioxide-based electrodes have shown a great performance in the electrochemical treatment of organic wastewater. In the present study, modified PbO2 anodes supported on stainless steel (SS) with a titanium oxide interlayer such as SS/TiO2/PbO2 and SS/TiO2/PbO2-10% Boron (B) were prepared by the sol–gel spin-coating technique. The morphological and structural properties of the prepared electrodes were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that the SS/TiO2/PbO2-10% B anode led to a rougher active surface, larger specific surface area, and therefore stronger ability to generate powerful oxidizing agents. The electrochemical impedance spectroscopy (EIS) measurements showed that the modified PbO2 anodes displayed a lower charge transfer resistance Rct. The influence of the introduction of a TiO2 intermediate layer and the boron doping of a PbO2 active surface layer on the electrochemical degradation of ampicillin (AMP) antibiotic have been investigated by chemical oxygen demand measurements and HPLC analysis. Although HPLC analysis showed that the degradation process of AMP with SS/PbO2 was slightly faster than the modified PbO2 anodes, the results revealed that SS/TiO2/PbO2-10%B was the most efficient and economical anode toward the pollutant degradation due to its physico-chemical properties. At the end of the electrolysis, the chemical oxygen demand (COD), the average current efficiency (ACE) and the energy consumption (EC) reached, respectively, 69.23%, 60.30% and 0.056 kWh (g COD)−1, making SS/TiO2/PbO2-10%B a promising anode for the degradation of ampicillin antibiotic in aqueous solutions.
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elhelece, Wael A. A. "Influence of Chemical Treatment on the Spectral and Thermal Behavior of Activated Carbon Obtained from Olive Oil Solid Waste." Journal of Physics: Conference Series 2305, no. 1 (August 1, 2022): 012032. http://dx.doi.org/10.1088/1742-6596/2305/1/012032.
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Abstract Solid waste remained after the extraction of oil from olive oil fruits (OOSW), was used to obtain active carbon depending on chemical activation using H3PO4, KOH and ZnCl2 as activating agents. The changes in composition due to chemical treatment and pyrolysis were investigated by chemical analysis, spectral (IR), and thermal analysis (DTA). Thermodynamic parameters of formation (activation energy (ΔEa*), enthalpy change (ΔH*), entropy change (ΔS*) and free energy change (ΔG*) related to the thermal decomposition process were calculated. Adsorption of both iodine and methylene blue at very low concentrations were done, the quantity of the iodine adsorbed (iodine number) indicated the micropores content of carbon by the uptake of iodine from the solution. It is equivalent to surface area of carbon between 900m2/g and 1100 m2/g. To characterize activated carbons as well as determining the adsorption capacity adsorption of methylene blue was done.
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Escamilla-García, Monserrat, Raquel A. Ríos-Romo, Armando Melgarejo-Mancilla, Mayra Díaz-Ramírez, Hilda M. Hernández-Hernández, Aldo Amaro-Reyes, Prospero Di Pierro, and Carlos Regalado-González. "Rheological and Antimicrobial Properties of Chitosan and Quinoa Protein Filmogenic Suspensions with Thyme and Rosemary Essential Oils." Foods 9, no. 11 (November 6, 2020): 1616. http://dx.doi.org/10.3390/foods9111616.
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Food packaging faces the negative impact of synthetic materials on the environment, and edible coatings offer one alternative from filmogenic suspensions (FS). In this work, an active edible FS based on chitosan (C) and quinoa protein (QP) cross-linked with transglutaminase was produced. Thyme (T) and rosemary (R) essential oils (EOs) were incorporated as antimicrobial agents. Particle size, Z potential, and rheological parameters were evaluated. The antimicrobial activity against Micrococcus luteus (NCIB 8166) and Salmonella sp. (Lignieres 1900) was monitored using atomic force microscopy and image analysis. Results indicate that EOs incorporation into C:QP suspensions did not affect the Z potential, ranging from −46.69 ± 3.19 mV to −46.21 ± 3.83 mV. However, the polydispersity index increased from 0.51 ± 0.07 to 0.80 ± 0.04 in suspensions with EO. The minimum inhibitory concentration of active suspensions against Salmonella sp. was 0.5% (v/v) for thyme and 1% (v/v) for rosemary. Entropy and fractal dimension of the images were used to confirm the antimicrobial effect of EOs, which modified the surface roughness.
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Padervand, Mohsen. "Well-Supported Ag3VO4–AgBr Nanostructures for Visible Light-Driven Treatment of Wastewaters." Progress in Reaction Kinetics and Mechanism 42, no. 3 (September 2017): 251–58. http://dx.doi.org/10.3184/146867817x14821527549176.
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Ag3VO4–AgBr nanoparticles were loaded on fluorapatite (FA) and carboxymethyl cellulose (CMC) supports by an ionic liquid-mediated precipitation method and used as effective visible light-driven photocatalysts for the degradation of Acid Blue 92 (AB92) azo dye as a typical wastewater. The products were characterised by powder X-ray diffraction (XRD), diffuse reflectance spectroscopy, FTIR, scanning electron microscopy (SEM) and nitrogen adsorption–desorption isotherms using Brunauer–Emmett–Teller (BET) analysis. The XRD patterns confirmed the formation of Ag3VO4 and AgBr crystalline phases. Moreover, the SEM images indicated that the photoactive agents were homogeneously dispersed on the surface and the average size of the particles was between 45 and 95 nm. During the treatment time, the photogenerated electron–hole pairs reacted with the species in the solution and produced OH•, HO2• and O2•– species which attacked the organic pollutants and destroyed the crucial bonds. Recycling experiments confirmed that the CMC-based photocatalyst was more active during the first time of using while the FA analogue was determined to be sufficiently active after five cycles of usage.
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Aidarova, Saule B., Assem B. Issayeva, Altynay A. Sharipova, Dmitry O. Grigoriev, Reinhard Miller, Tulegen M. Seilkhanov, Alpamys A. Babayev, and Miras O. Issakhov. "Analysis of NMR Spectra of Submicro-Containers with Biocide DCOIT." Colloids and Interfaces 4, no. 4 (December 9, 2020): 56. http://dx.doi.org/10.3390/colloids4040056.
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Nowadays, the search for and development of new forms of materials with biocides is an actual problem of the modern science of nanosized materials due to the problem of microbiological contamination, which can be solved by using nanocontainers carrying biocides. Depending on the morphology of the nanocontainers and the filled active agents, it is possible to create coatings with specially designed self-healing functionality or multifunctional properties. The purpose of this work was to produce submicro-containers (SMCs) with a shell of SiO2 nanoparticles and a core of polymerized 3-(trimethoxysilyl) propyl methacrylate filled with 5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) in an oil in water (O/W) emulsion. The chemical nature of the individual components of the system and nano-capsules were investigated using NMR spectroscopy. The size and zeta potential of the SMCs were measured by a dynamic light scattering method (d = 170–180 nm, polydispersity index PDI = 0.125 and zeta-potential = 55 mV), the morphology of their outer surface was determined using SEM. The results of NMR analysis showed that during the addition of the biocide into the SMCs, its chemical structure is retained, as is its activity. Minor changes in the chemical shifts of the 1H NMR spectra of the SMCs with DCOIT, as well as of the biocide itself, confirm the inclusion of DCOIT inside the SMCs.
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ANDERSON, ANTHONY M., and STEPHEN H. DAVIS. "Solidification of free liquid films." Journal of Fluid Mechanics 617 (December 25, 2008): 87–106. http://dx.doi.org/10.1017/s0022112008003753.
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We examine steady longitudinal freezing of a two-dimensional single-component free liquid film. In the liquid, there are thermocapillary and volume-change flows as a result of temperature gradients along the film and density change upon solidification. We examine these flows, heat transfer, and interfacial shapes using an asymptotic analysis which is valid for thin films with small aspect ratios. These solutions depend sensitively on contact conditions at the tri-junctions. In particular, when the sum of the angles formed in the solid and liquid phases falls below a critical value, the existence of steady solutions is lost and the liquid film cannot be continuous, suggesting breakage of the film owing to freezing. The solutions are relevant to the freezing of foams of metals or ceramics, materials unaffected by surface active agents.
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Dandamudi, Akhila, William Seibel, Huzoor Akbar, and Yi Zheng. "Structure-Activity Relationship Analysis of Analogs of Rhosin, a RhoA Inhibitor, Reveals a New Generation of Improved Antiplatelet Agents." Blood 138, Supplement 1 (November 5, 2021): 3989. http://dx.doi.org/10.1182/blood-2021-153108.
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Abstract Platelet activation and aggregation play a key role in mediating hemostasis and thrombosis. The antiplatelet therapies currently available in the market are associated with a high risk of hemorrhage and are mostly irreversible in suppressing platelet activity; hence, there is a need to develop better therapeutic agents. Previous genetic and pharmacological studies have implicated the small GTPase RhoA in multiple platelet signaling pathways. We devised a lead RhoA activity-specific inhibitor, Rhosin/G04, based on the structure-function relationship of RhoA interaction with its activator, guanine nucleotide exchange factor (GEF) (Figure 1A). Rhosin/G04 binds to RhoA directly with micromolar affinity at a surface groove that is essential for GEF recognition and blocks GEF-mediated GTP loading to RhoA. Rhosin/G04 inhibits platelet spreading on fibrinogen and thrombin-induced platelet aggregation, mimicking effects of RhoA gene targeting. In the current work, we have utilized the inhibitory activity of G04 for platelet activation and its biochemical activity to define its structure-activity relationship (SAR) and to understand its mechanism of action in an effort to improve efficacy and druggability. The structure of G04 in a groove of RhoA interaction was hypothesized based on the docking studies using Molsoft ICM-Pro. Cincinnati Children's Hospital Medical Center's compound library of over 360,000 chemicals was scanned for G04 analogs by similarity and substructure searches. In the initial screen, a human platelet aggregation assay was performed at both a low concentration (1 µg/ml) and a high concentration (5 µg/ml) of collagen. The first round similarity search resulted in a set of 7 compounds (Set-1), from which, compound 177629 showed significantly enhanced potency relative to G04 (Figure 1B). The second round of similarity searches for compounds more closely related to 177629 (Set-2) identified 14 compounds. The third-round search for other related compounds (Set-3) led to 9 additional compounds that add to the understanding of the SAR. The compounds that showed enhanced antiplatelet activity were examined for their potency and selectivity in in vitro biochemical binding assays and in suppressing RhoA-GTP formation and downstream phosphorylation of myosin light chain (p-MLC) signaling in platelets. The active compounds were further examined for their anti-platelet activities under diverse stimuli including thrombin, ADP, U46619 (a stable thromboxane receptor agonist), and arachidonic acid. The most active compounds from Set-1, Set-2, and Set-3 inhibited platelet aggregation by at least 70% and showed IC 50 values below 6 µM. Of these compounds, 12 showed significantly greater potency than the initial compound, G04. The most active compounds were 177618, 177619, 177628, 177629, 177633, and 177634. These compounds specifically inhibited RhoA activity and blocked p-MLC. SAR analyses led us to believe that the quinoline is optimally attached to the hydrazine at the 4-position. The halogen (choloro- or trifluoromethyl-) substitution at the 7- or 8- position improved activity, and the 7- position may be slightly favored. The aryl group is considerably variable with similar potency between the indole, methylphenyl, and dichlorophenyl- groups. Rhosin/G04 is the R enantiomer (i.e. Rhosin is R-G04), so its S enantiomer, S-G04 was also evaluated (Figure 1C). S-G04 is significantly more potent than R-G04 in inhibiting collagen-stimulated RhoA-GTP formation and aggregation of platelets, and its effect is completely reversible by washing the platelets. Finally, R-G04 and S-G04 showed differential inhibition of arachidonic acid and U46619 stimulated primary and secondary aggregation, highlighting the potential utilities of the inhibitors in dissecting different platelet activation mechanisms. S-G04 is active in inhibiting thrombin, ADP, U46619, and arachidonic acid-mediated platelet activation at submicromolar concentration, suggesting a broad role of RhoA signaling in integrating platelet signal cross talk. In summary, evaluation of Rhosin/R-G04 analogs in a platelet activity screen identified a new generation of improved small-molecule RhoA inhibitors, including an enantiomer with significantly improved efficacy. These analog studies of novel anti-platelet agents provide a new approach to effectively and reversibly manipulate platelet activities. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.
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Call-Cummings, Meagan, Melissa Hauber-Özer, and Karen Ross. "Struggling with/against the unintentional reproduction of power structures in participatory research: Using reconstructive horizon analysis." Action Research 18, no. 2 (April 3, 2019): 171–93. http://dx.doi.org/10.1177/1476750319837324.
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Shared power and democratic decision making are core epistemological commitments of participatory action research. Scholars who engage in participatory action research with youth seek to share ownership and disrupt adult/child or knower/learner binaries traditional in the Global North, in which adults are the active agents who own and transfer knowledge to children, who remain in a passive role. Yet, we have noticed during several of our projects with youth that, despite our best efforts, these knower/learner binaries can be reproduced with younger coresearchers as we exhibit care in the form of protection and provision of security. In this article, we examine three scenes from our recent youth participatory action research projects using reconstructive horizon analysis to surface and explore backgrounded validity claims that highlight the tensions between our efforts to democratize the research process and our commitment to an ethic of care for those with whom we engage in participatory knowledge production. We suggest that explicit attention to these tensions as part of the inquiry process is important for making participatory research with youth a more equitable endeavor and to build the validity of such work.
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Perez, Javier Christian Ramirez, Tatiana Alves Dos Reis, and Marcia de Almeida Rizzutto. "Identifying and detecting Entomopathogenic fungi using Surface-enhanced Raman spectroscopy / Identificação e detecção de fungos entomopatogênicos utilizando Superficie-enhanced Raman espalhamento." Brazilian Journal of Animal and Environmental Research 4, no. 4 (October 1, 2021): 4833–51. http://dx.doi.org/10.34188/bjaerv4n4-002.
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In the natural ecosystem, fungal entomopathogens are the most efficient biocontrol agents against insect pests. In this study we offer an alternative for conventional fungal diagnostic, Surface-enhanced Raman spectroscopy (SERS) technique combine with principal component analysis (PCA) for detection and identification three entomopathogenic fungi, namely, IBCB 66 Beauveria bassiana, IBCB 130 Isaria fumosorosea, and IBCB 425 Metarhizium anisopliae. Using a simple preparation approach, highly active silver nanoparticles suitable for detecting complex biomolecules were produced for application in the SERS technique. Entomopathogens fungi produced highly enhanced and reproducible Raman signals based on their biochemical composition due to the high density of hot spots at the confluence of silver nano-aggregates, allowing the three entomopathogens species to be differentiated in the SERS spectrum fingerprint region, 550-1700 cm-1. The SERS method, along with PCA analysis, accounted for over 99 % of total variance and allowed for very high probability discrimination between the three entomopathogens, allowing taxonomic affiliation to be determined in a short period of time. These findings suggest that the SERS methodology can be used to develop a new, fast, accurate, and cost-effective diagnostic method for fungal entomopathogens.
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Sułek, Adam, Barbara Pucelik, Marcin Kobielusz, Przemysław Łabuz, Grzegorz Dubin, and Janusz M. Dąbrowski. "Surface Modification of Nanocrystalline TiO2 Materials with Sulfonated Porphyrins for Visible Light Antimicrobial Therapy." Catalysts 9, no. 10 (September 29, 2019): 821. http://dx.doi.org/10.3390/catal9100821.
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Highly-active, surface-modified anatase TiO2 nanoparticles were successfully synthesized and characterized. The morphological and optical properties of the obtained (metallo)porphyrin@qTiO2 materials were evaluated using absorption and fluorescence spectroscopy, scanning electron microscopy (SEM) imaging, and dynamic light scattering (DLS). These hybrid nanoparticles efficiently generated reactive oxygen species (ROS) under blue-light irradiation (420 ± 20 nm) and possessed a unimodal size distribution of 20–70 nm in diameter. The antimicrobial performance of the synthetized agents was examined against Gram-negative and Gram-positive bacteria. After a short-term incubation of microorganisms with nanomaterials (at 1 g/L) and irradiation with blue-light at a dose of 10 J/cm2, 2–3 logs of Escherichia coli, and 3–4 logs of Staphylococcus aureus were inactivated. A further decrease in bacteria viability was observed after potentiation photodynamic inactivation (PDI), either by H2O2 or KI, resulting in complete microorganism eradication even when using low material concentration (from 0.1 g/L). SEM analysis of bacteria morphology after each mode of PDI suggested different mechanisms of cellular disruption depending on the type of generated oxygen and/or iodide species. These data suggest that TiO2-based materials modified with sulfonated porphyrins are efficient photocatalysts that could be successfully used in biomedical strategies, most notably, photodynamic inactivation of microorganisms.
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Babaee, Saeed, Zahra Monjezi, and Milad Saadat Tagharoodi. "Statistical Taguchi Optimization for Preparation and Adhesion Evaluation of Epoxy Insulator to the Surface of Double Base Propellant Grain." Journal of New Developments in Chemistry 2, no. 1 (December 8, 2018): 38–47. http://dx.doi.org/10.14302/issn.2377-2549.jndc-18-2479.
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In this work, Taguchi design (orthogonal array, OA9) was used for the adhesion investigation of an epoxy insulator to a double base (DB) propellant grain. In this manner three epoxy resins based on diglycidylether bisphenol A (DGEBA) and three polyamine curing agents with an active diluent based on DGEBA were used. Therefore, the effects of resin type, curing agent type with its amount and diluent quantity as main factors were investigated on the single lap shear strength (adhesion strength) and then the results were quantitatively evaluated by the analysis of variance (ANOVA). The data given of ANOVA predicted that the best adhesion strength of 15.584 ± 1.606 MPa was obtained for the optimum conditions of MANA POX-102 as epoxy resin, H-37 as curing agent with 57 phr, ERYSYS GE-30 as diluent with 5 phr. In comparison, practical result of adhesion strength obtained for the optimum conditions was 15.4 ± 0.2 MPa. Also the Pull-off test results on the surface of the DB propellant showed that the maximum adhesion strength (related to the optimal conditions) is 2.64 ± 0.2 MPa.
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Kostevšek, Nina. "A Review on the Optimal Design of Magnetic Nanoparticle-Based T2 MRI Contrast Agents." Magnetochemistry 6, no. 1 (February 28, 2020): 11. http://dx.doi.org/10.3390/magnetochemistry6010011.
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Relaxivity r2 and thus the contrast efficacy of superparamagnetic nanoparticles (NPs) can be enhanced via either NP’s magnetic properties or coating optimization. Numerous reports can be found about the investigation of the optimal iron oxide nanoparticles (IO NPs) size, shape, crystallinity and composition that yield high saturation magnetization (ms) values and, consequently, high r2 values. Although the use of an appropriate coating can boost up the NPs MRI contrast agent efficiency, this topic has been largely understudied. Therefore, in this review, the factors affording r2 enhancement of spherical magnetic NPs are discussed. Based on the literature, the requirements for an optimal surface coating that may increase r2 values and ensure stability and biocompatibility of NPs are listed. One of the best candidates that fulfil these requirements are liposomes with embedded magnetic NPs, so-called magneto-liposomes. The analysis of the literature elucidated the most appropriate phospholipid compositions for the relaxivity enhancement and for magneto-liposomes in vivo stability. Finally, the future directions in the development of NP-based contrast agents are given. For example, most of the synthetic NPs are recognized and eliminated as a foreign substance by the immune system. To overcome this issue, a design of a biomimetic, cell-membrane-based nanocarrier for contrast agents is proposed. Disguised with cell membranes, NPs or other active components can act as autogenous cells and thus ensure the inherent biocompatibility.
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McMaster, W. R., C. J. Morrison, M. H. Macdonald, and P. B. Joshi. "Mutational and functional analysis of the Leishmania surface metalloproteinase GP63: similarities to matrix metalloproteinases." Parasitology 108, S1 (March 1994): S29—S36. http://dx.doi.org/10.1017/s0031182000075697.
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SUMMARYThe major surface glycoprotein of Leishmania, referred to as GP63, is a zinc metalloproteinase of 63000 Mr present on promastigotes and amastigotes from diverse species of Leishmania. GP63 shares several characteristics with the members of the matrix metalloproteinase family including degradation of at least one component of the extracellular matrix, location at the cell surface, requirement for Zn2+ for proteinase activity and inhibition of the proteinase activity by chelating agents and α2–macroglobulin. Site-directed mutagenesis of the cloned L. major GP63 genes was carried out to determine whether the proposed active site of Leishmania GP63 was homologous to those of other zinc metalloproteinases. The codon encoding the catalytic glutamic acid was modified to encode an aspartic acid and when expressed in COS–7 cells the resulting mutant GP63 had no demonstrable proteinase activity compared to wild type GP63. GP63 was predicted to be synthesized as a precursor protein containing a pro region at the NH2–terminus of GP63 implicated to be involved with the regulation of proteinase activity. As with many other proteinases, including matrix metalloproteinases, these enzymes are synthesized as latent proteinases that require activation for full proteinase activity. L. major recombinant GP63 (rGP63) has been produced in the baculovirus expression system where rGP63 was secreted as a latent proteinase. To study the activation of baculovirus rGP63, purified rGP63 was incubated with the mercurial compound, HgCl2, at concentrations previously shown to result in activation of other latent matrix degrading metalloproteinases and resulted in a significant enhancement of GP63 proteinase activity. The similarity of GP63 to the family of matrix-degrading proteinases suggests that the proteinase activity of GP63 maybe involved with the pathology of lesion formation in the mammalian host and may also be involved with the promastigote life stage in the sandfly vector. To study the functional role of GP63 proteinase, mutant strains of L. major, deficient in the expression of GP63, are currently being derived by targeted gene deletion. Using this strategy results have demonstrated the deletion of an entire L. major GP63 locus, containing in total six GP63 genes. Strategies to delete the second GP63 gene locus are developed and will determine whether deletion of both loci results in viable promastigotes. L. major strains deficient in the expression of GP63 may then be used to address the function of GP63 glycoprotein in the life cycle of Leishmania.
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Gao, Wen Yuan, Xing Xin Jia, Mei Hong Niu, Nai Ling Tang, and Zhi Qiang Hu. "Preparation of Nano-TiO2 in Inverse Micro-Emulsion System with Compound Surfactant." Advanced Materials Research 412 (November 2011): 25–31. http://dx.doi.org/10.4028/www.scientific.net/amr.412.25.
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The nanosized TiO2 is prepared by micro-emulsion process in the system of cyclohexane / [Span80 combined with OP-10] / water with TiCl4 as raw material. The selection method of the surface-active agents was investigated and the influence of amount of surfactant, water / oil ratio and concentration of reactants on the particle size were discussed in this work. The temperature schedule, crystal structure, particle size distribution and appearance of the nanocrystalline TiO2 were analyzed by differential thermal analysis (DTA) combined with X-ray diffraction (XRD), laser particle size analysis (LPSA) and scanning electron microscope (SEM). The results showed that: under these conditions of mixture of 8g Span80 and 2g OP-10 as the emulsifier, water / oil mass ratio of 1/4, TiCl4 concentration of 0.6mol / L and calcinations temperature of 510°C, nanoTiO2 powder with smaller particle size and better dispersion was prepared . And the average size of the product was 27.3nm.
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Piferi, Cecilia, Ruggero Barni, H. Eduardo Roman, and Claudia Riccardi. "Current Filaments in Asymmetric Surface Dielectric Barrier Discharge." Applied Sciences 11, no. 5 (February 26, 2021): 2079. http://dx.doi.org/10.3390/app11052079.
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In this study, we examine the statistical properties of asymmetric surface dielectric barrier discharges (SDBD) produced by applying a periodic high voltage between two conducting displaced electrodes, located at the opposite sides of a flat dielectric panel. Here, the asymmetry refers to the fact that the lower electrode is fully covered with an insulating material, while the upper one, glued onto the dielectric surface, is otherwise left exposed to the air. Such a configuration allows the formation of a thin layer of plasma above the insulating surface. A single cycle signal consists of two well-separated half-cycle patterns, denoted as forward and backward strokes, corresponding to positive and negative voltages, respectively. They display a quite complex discharge pattern constituted by a sequence of individual peaks (bursts) of varying current and time duration. Specifically, we find that backward stroke bursts carry a positive mean charge Q≃0.3 nC and mean current I≃35 mA, with a mean duration τ≃15 ns, while forward stroke bursts have a negative mean charge Q≃−0.1 nC, a mean current I≃−20 mA, and a mean duration τ≃11 ns. The statistical analysis suggests that power injection can be tailored to produce the active agents in the plasma needed for a particular application. We also determined discharge spatial correlation patterns from measurements of the associated stimulated optical emission. The optical excitations occur as a result of the ionizing effect of the electromagnetic waves which ignite the discharge, followed by the electric current flow. In particular, we point out that one of the phases of the discharge is compatible with a cathode directed streamer phenomenon (backward stroke), while the mechanism acting for a forward stroke has a different structure.