ADVANCES IN NATURAL EXTRACTS USED FOR ANTIBIOTIC-RESISTANT BACTERIA TREATMENT: THE GRAM-NEGATIVE CASES
Background: Infectious diseases are a global problem, the second human cause of death. Infectious diseases caused by pathogenic bacteria have been treated with a high degree of efficacy. However, even when the 20th century was considered the “golden age” of antibiotics, bacteria developed a different resistance mechanism to antibiotics. In 2017, the WHO issued an alert about 12 bacteria with an urgent need to develop new antibiotics. Aims: The aim of the present review is to analyze the current knowledge of the antibacterial activity of natural extract-based treatments against the pathogens listed by WHO. Methods: A systematic review of the literature in PubMed was performed to search for publications describing the use of natural extracts as antibiotics over bacteria. We focused on the Gram-Negative group. The exclusion criteria consisted of limiting papers on natural extracts tested over the bacteria culture related to eight selected bacteria, according to an alert issued by WHO in 2017, and seven plant extracts. Results: All the Gram-Negative bacteria listed in 2017 by WHO have been treated, with different degrees of advance, with some of the plant extracts and plant-based compounds reviewed. In general, the first approach is using inhibition disks applied over the bacterial biofilm in solid culture media. Discussion: While Salmonellae and P. aeruginosa have been extensively studied, over N. gonorrhoeae, A. baumannii have been tested with fewer natural extracts. Edible herbs are more often used, as well as artemisa and wine byproducts. In all cases, they are in the early stages of study, not being tested in patients at present. Conclusions: Plant extracts and plant-based compounds are effective as antibacterial, with minimal effects on the host cell. Furthermore, they are sustainable, environmentally friendly, and renewable.
Read ArticleCOMPARISON OF TWO STAINING METHODS FOR ANODIZING IN ALLOY 6063 ALUMINUM PROFILES
Background: Aluminum stands out for being a light, corrosion-resistant, and recyclable metal, achieving wide coverage in the market. When incorporated into alloying elements, it is possible to acquire other desirable characteristics. Alloy 6063, intended for architectural purposes, has aesthetic, structural, and strength functions. Anodized finishing is performed through an electrolytic process, ensuring a more resistant aluminum oxide film than that formed naturally. For decorative purposes, the anodic film coloration can be performed by several methodologies, in this case, for the coloration by organic adsorption, with the use of aniline, and the electrolytic coloration, composed of tin sulfate salts, both for obtaining the black color. Aim: Compare of two different staining methods on the surface of anodized profiles of aluminum alloy 6063. Methods: Profile samples were collected and tests were carried out to measure the thickness of the anodic layer, immersion tests with 3,5 percent sodium chloride, for 1000 hours, and neutral saline mist, for 600 hours. Results and Discussion: Both methodologies proved to be resistant to immersion tests with sodium chloride, as well as with neutral saline mist, and these tests are quite aggressive and provide corrosion of the material when not well treated. Corrosion points were only seen at the intersections performed, and in the rest of thearea, no points were detected. Conclusions: The result of both methodologies was positive, considering tht there was no corrosion in the tested samples, except in the intersections performed, as well as the maintenance of the color in both tested methodologies, which was not expected in the literature. For future work, it is suggested to deepen the study to perform electrochemical impedance spectroscopy tests for exaluate the strength of the anodic film and perform anodizing with the same parameters, however, with different anilines to analyze their behavior.
Read ArticleCOMPARATIVE STUDY OF DPD REAGENTS FOR CHLORINE MEASUREMENT IN DRINKING WATER AND DEVELOPMENT OF A JAVASCRIPT INTERPOLATION TOOL
Background: Determining chlorine in water ensures safety. Among other methods, the DPD colorimetric method is used. The DPD Method relies on colorimetric reactions to measure free and total chlorine concentration in water samples with pink compound formation. Aims: To perform a comparative chlorine analysis using DPD, assessing reagents from 3 makers and 2 Hach instruments to identify disparities and propose adjustments for more accurate measurements. Methods: Hach High-Range and Low-Range Free chlorine determination procedures were followed. DR300 and POCKET Colorimeter II spectrophotometers were used. Tests were conducted for each DPD manufacturer in low/high ranges and in two HACH devices to determine the chlorine concentrations. Hach was used as the reference; LaMotte and PoliControl compared against it. Statistical analyses were compiled using MS Excel. Results: The tests findings were gathered in Tables 1-5. JavaScript and HTML scripts were created to convert LaMotte and PoliControl outcomes into values equivalent to those of HACH through linear interpolation. Discussion: Various DPD reagents and equipment provided slightly different readings, prompting empirical evaluation of these differences. Adjusting the results to Hach's results was selected as both the reagent and spectrophotometer were from the same brand. Differences in spectrophotometer readings were more pronounced in high-range tests nearing the upper limit of the test. Conclusions: Equipment variations caused minor result differences; DPD reagents are not interchangeable without correlation. The Open-source code developed aided in reducing reading disparities.
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