Resistance Testing Research Articles

<i>Salmonella</i> and <i>Yersinia enterocolitica</i> through the pig meat chain in Sardinia: occurrence, antimicrobial resistance and genetic insight

The study aimed to characterize Salmonella and Yersinia enterocolitica detected in fattening pigs in Sardinia, examining genetic similarity and antimicrobial resistance of isolates from farms and slaughterhouses and evaluating carcass hygiene. Environmental samples were collected from six pig farms, and the same pigs were also sampled at the slaughterhouses. Palatine tonsils, mesenteric lymph nodes, colon content, and carcass surface samples were collected and tested for Salmonella and Y. enterocolitica. Antimicrobial resistance testing and whole genome sequencing were performed on all isolates. Carcass surface samples were tested for total aerobic colony count (ACC) and Enterobacteriaceae count (EBC). Y. enterocolitica was found in two farms (33%), while Salmonella was absent in environmental farm samples. At slaughterhouses, 13.1% of pigs were found positive for Salmonella (lymph nodes, colon content, and palatine tonsils samples), but Y. enterocolitica was not detected. Salmonella isolates were typed as monophasic S. Typhimurium ST34 and S. Goldcoast ST358, with few allelic differences among isolates of the same ST. Salmonella ST34 showed resistance towards ampicillin, streptomycin, sulfonamide, and tetracycline (blaTEM-1B, aph(3´´)-Ib, sul2 and tetB genes, R-type ASSuT). Y. enterocolitica isolates (biotype 2, ST853, and ST859) showed resistance to ampicillin and amoxicillin-clavulanic acid (blaA gene). Process hygiene criteria were generally met, with mean (log10 CFU/cm2 ± standard deviation) values for ACC and EBC being 2.23±0.74 and 0.75±0.81. Pigs of Sardinia are confirmed carriers of Salmonella and Y. enterocolitica, but overall hygienic status in farms and slaughterhouses in Sardinia is acceptable. Monophasic S. Typhimurium and Y. enterocolitica isolates showed typical resistance patterns. Monophasic S. Typhimurium ST34 isolates with R-type ASSuT are confirmed as epidemic clones.

The Effect Of Pylates-Based Exercıse Programs On Gırls' Quıckness And Strength

ABSTRACT To investigate the effects of Pilates-based exercise programs on girls' quickness and strength. Conducted at a private Pilates studio in Kırıkkale, the research involved 50 female students aged 9-10 years, with 25 in the experimental group and 25 in the control group. A 10-week training program included exercise sessions twice a week, focusing on basic Pilates movements, balance, and strength development. Quickness and strength levels were assessed at the beginning and end of the study using specific tests. Quickness was measured through short-distance running and reaction tests, while strength was assessed by the number of repetitions in various exercises and resistance tests. The findings indicated that Pilates-based exercise programs positively impacted the quickness and strength of the girls. Specifically, Pilates movements were particularly effective in enhancing muscle strength and developing quickness. These results suggest that Pilates exercises can effectively contribute to the physical development of children. It is recommended that educators and coaches implement Pilates-based programs for children, considering the benefits of such exercises.

Evaluation of Physiological Changes in Important Dried Apricot Varieties Under Drought Stress

Nearly all of the apricot varieties grown in Malatya are dried apricots and the plantation areas in this region are expanding daily. Due to the impact of climate change, producers are growing apricots mostly under limited irrigation or even dry conditions. Therefore, it is essential to determine the drought resistance characteristics of the varieties commonly cultivated in this region. In this study, different irrigation levels of 100%, 75%, 50% and 25% of available water were applied to Hacıhalioğlu, Kabaaşı, Çataloğlu, Hasanbey and Soğancı apricot varieties. To evaluate the resistance of the varieties to drought stress and its relationship with physiological changes, chlorophyll a and b, carotenoids, total sugar, total starch and abscisic acid contents in the leaves were analyzed. A decrease in chlorophyll a and b, carotenoids, total starch values and an increase in total sugar and ABA values were determined due to the decrease in irrigation rates. In Kabaasi and Hasanbey varieties, which were observed as the most resistant to water shortage, chlorophyll a and b, carotenoids, total starch values were higher and total sugar content was lower at decreased irrigation levels. No difference was detected between varieties in ABA values. As a result of the observations in the drought resistance tests and physiological analyses, it was concluded that the most resistant varieties were Kabaasi and Hasanbey. Unfortunately, the most sensitive variety was the most widespread Hacihaliloglu. In addition, analyzing and evaluating the physiological changes occurring in apricot under drought stress will be useful in developing the most appropriate irrigation strategies for each variety and increasing water use efficiency. It may also be useful in cross-breeding studies to develop new drought-resistant varieties.

Bioactive Properties of Phosphate-Modified Silicon Oxycarbide Protective Coatings: Morphology and Functional Evaluation.

This article presents a study on the functional properties and morphology of coatings based on amorphous silicon oxycarbide modified with phosphate ions and comodified with aluminum and boron. The objective of this modification was to enhance the biocompatibility and bioactivity without affecting its protective properties. The comodification was aimed toward stabilization of phosphate in the structure. The coatings were prepared according to the typical procedure for polymer-derived ceramics: synthesized via the sol-gel method, deposited using the dip-coating technique, and subsequently pyrolyzed. Comprehensive analyses of the morphology, surface properties, corrosion resistance, and bioactivity were conducted to assess their functional performance. The coatings exhibited uniform and smooth surfaces, with phase separation observed in the boron-modified SiBPOC series. Surface wettability and free energy measurements demonstrated that SiPOC and SiBPOC coatings possessed moderate hydrophilicity and favorable surface free energy for cell adhesion and bone tissue mineralization. Corrosion resistance tests in Ringer's solution revealed that SiBPOC coatings provided the highest protection against ion leaching, while SiAlPOC showed decreased resistance due to surface cracks. Bioactivity tests indicated calcium phosphate precipitation on the surface of all samples with higher hydroxyapatite formation on SiPOC and SiAlPOC coatings. In vitro tests using MG-63 osteoblast-like cells confirmed the biocompatibility of the coatings, with SiPOC and SiBPOC exhibiting the best combination of bioactivity, cell adhesion, and proliferation. These findings suggest that the phosphate- and boron-modified SiOC-based coatings are promising candidates for enhancing bone integration in orthopedic implants.

Thymidine Analogue Mutations with M184V Significantly Decrease Phenotypic Susceptibility of HIV-1 Subtype C Reverse Transcriptase to Islatravir

Islatravir (ISL) is the first-in-class nucleoside reverse transcriptase translocation inhibitor (NRTtI) with novel modes of action. Data on ISL resistance are currently limited, particularly to HIV-1 non-B subtypes. This study aimed to assess prevalent nucleos(t)ide reverse transcriptase inhibitor (NRTI)-resistant mutations in HIV-1 subtype C for their phenotypic resistance to ISL. Prevalent single and combinations of NRTI-resistant mutations were selected from a routine HIV-1 genotypic drug resistance testing database and introduced into HIV-1 subtype C-like pseudoviruses, which were then tested for ISL susceptibility. Single NRTI-resistant mutations were susceptible or showed only a low level of resistance to ISL. This included thymidine analogue mutations (TAMs, i.e., M41L, D67N, K70R, T215FY, and K219EQ) and non-TAMs (i.e., A62V, K65R, K70ET, L74IV, A114S, Y115F, and M184V). Combinations of M184V with one or more additional NRTI-resistant mutations generally displayed reduced ISL susceptibilities. This was more prominent for combinations that included M184V+TAMs, and particularly M184V+TAM-2 mutations. Combinations that included M184V+K65R did not impact significantly on ISL susceptibility. Our study suggests that ISL would be effective in treating people living with HIV (PLWH) failing tenofovir disoproxil fumarate (TDF)/lamivudine (3TC) or TDF/emtricitabine (FTC)-containing regimens, but would be less effective in PLH failing zidovudine (AZT) with 3TC or FTC-containing regimens.

Influence of Textural and Compositional Heterogeneities on the Staining of Silicate Ornamental Rocks

Objective: This study aims to compare the results of staining tests carried out on natural silicate ornamental stone samples. The staining test was applied to different regions of the same slab of rock, assessing the behavior of a staining agent, oil, in relation to the textural variations and compositional characteristics of the natural rocks investigated. From this analysis, we hope to better understand how these properties influence the interaction with the staining agent, contributing to knowledge about the durability and aesthetic maintenance of ornamental stones in commercial use. Theoretical background: Ornamental stones, as well as being beautiful, must be durable and functional, maintaining their aesthetic, physical and chemical properties (ASTM, 2005). However, cleaning products, food and environmental factors can alter these characteristics. Aires-Barros (1991) defines this “alterability” as a function of intrinsic factors (material and porosity), extrinsic factors (environment) and time, which together determine the durability of stone. Method/project/approach: A study compared the behavior of three types of stone exposed to oil as a staining agent, applying a stain resistance test methodology. The procedure followed Document 20 of the ABIROCHAS Technical Documents Collection on the technological characterization of cladding stones and the practices described by Castilho (2018) in Technological Characterization of Ornamental Stones: Laboratory Practices. Results and conclusion: The study carried out in this work showed that the same slab of natural ornamental stone can have areas that are more susceptible to oil staining than other areas on the same slab. The areas with the finest crystalline texture and consequently the least expressive cracking were the areas least affected by oil staining. Another observation based on the results obtained was the loss of shine associated with the areas subjected to staining, even those where the stain was visually removed. In addition to these observations, the color of the ornamental stone, as well as the type of surface finish on the slabs, may also be important variables in the effect of oil staining, since the Anthracite stone with a black color and brushed surface finish was the lithotype that did not show stains after contact with oil. Implications of the research: Natural ornamental stone comprises materials with textural, compositional and structural heterogeneities observed even in a single slab, so the work seeks, through comparisons, to observe areas of greater susceptibility in natural ornamental stone slabs that can interact with oil staining agents. Originality/value: to contribute to the improvement of technologies that contribute to the best performance of natural ornamental stones, taking into account the type of resin and associated finishes.

Novel calibration method for fine soil electrical resistivity based on van der Pauw configuration

Abstract Soil electrical resistivity (ER) serves as an important parameter for indirectly monitoring various physical properties. The Miller box, based on Ohm’s Law, is commonly employed to measure resistivity. However, its probes tend to insert destructively into the soil sample. Van der Pauw (vdP) method is a classical, non-destructive technique used for measuring the ER of thin samples. Applying the vdP method to soil, which is a non-flat sample, presents certain challenges. In this paper, a novel soil resistivity calibration method (vdP box) is developed based on the vdP method, with consideration given to thickness extension. The relative resistivity error between the VDP box and Miller box for fine soil is less than 1% with various diameters and moisture content, which verified the accuracy and stability of the new device. This device achieves simple, fast, and non-destructive testing of soil resistivity and provides a novel method to study other properties of soil indirectly through resistivity.

Determination of antimicrobial resistance genes in patients with infected miscarriage. A rapid identification and optimized empirical therapy

BACKGROUND: The infectious factor during pregnancy remains the leading cause not only of maternal mortality, but also of premature pregnancy loss and subsequent reproductive function impairment. Patients with infected miscarriage represent a special cohort in terms of complexity of clinical decision-making, while the choice of antimicrobial chemotherapy is particularly difficult in conditions of accumulation of scientific knowledge about the main microbial agents. For adequate treatment, it is essential to use all modern methods of microbiota diagnosis and conduct regular monitoring of microorganism resistance in order to update empirical schemes of antibacterial therapy. AIM: The aim of this study was to evaluate the correlation relationship between antimicrobial resistance genes and identified microbial agents in patients with infected miscarriage in order to optimize empirical antimicrobial chemotherapy. MATERIALS AND METHODS: We prospectively studied 42 samples of genital tract discharge in patients with infected miscarriage. The classical culture method was used to determine microorganism sensitivity to standard antibacterial drugs by the disc diffusion test. A molecular genetic study of the species composition of clinically significant microbial agents and genes of resistance to β-lactam and glycopeptide antibiotics was performed using Femoflor Screen and BakRezista GLA test systems (“DNA-Technology” LLC., Russia), respectively. RESULTS: In the cultural study, one microbial agent was identified in 59.5% of cases, two in 40.0% of cases, and three in 7.1% of cases. The following microorganisms were most frequently identified: Enterococcus spp. in 25.0% of cases, Esherichia coli in 16.7% of cases, and Candida spp. in 11.7% of cases. During the molecular genetic study, Lactobacillus spp. were identified in 64.3% of the samples, the microorganisms associated with bacterial vaginosis in 45.3% of the samples, Candida spp. in 23.8% of the samples, and Herpesviridae family viruses in 14.3% of the samples. In 45.2% of the samples, one to 14 genes of resistance to β-lactam and glycopeptide antibiotics were identified, while Tem (19.0%), Oxa-40-like (19.0%), Stx-M1 (14.3%), Ges (14.3%), Oxa-51-like (11.9%), and Van A/B (9.5%) were most frequently determined in the samples positive for resistance genes. Comparison between phenotypic susceptibility testing and genetic prediction for antibiotics resistance demonstrated that the specificity varied from 96.4 to 100%, and the sensitivity from 40.0 to 85.7%. CONCLUSIONS: The use of molecular genetic diagnostic methods allows for the identification of clinically significant urogenital tract infections and the detection of markers of their resistance to β-lactam antibiotics and glycopeptides in the shortest possible time. The data obtained make it possible to optimize the initial antimicrobial chemotherapy.

Antibiotic patterns of ampicillin, streptomycin, and tetracycline in stray cats

This research was conducted to determine the presence of Escherichia coli bacteria in anal swabs of wild cats, determine the existence of antibiotic resistance in Escherichia coli bacteria, and determine resistance patterns in Escherichia coli bacteria. A total of 90 swab samples were taken, consisting of 30 anal swab samples from wild cats in the East Surabaya Region and 30 anal swab samples from wild cats in the West Surabaya Region. Samples were tested at the Veterinary Health Laboratory, Faculty of Veterinary Medicine, Wijaya Kusuma University, Surabaya. Samples were brought using buffered peptone water. Samples were isolated and identified using Mac Conkey Agar differential selective media. Isolates identified as Escherichia coli were then subjected to gram staining tests, biochemical tests, and sensitivity tests to determine the presence of resistance and multidrug resistance. The results of the study showed that 95.5% (86/90) of the samples contained Escherichia coli bacteria and the results of the sensitivity test showed that there was antibiotic resistance showing that 25.5% (22/86) were resistant to the antibiotic ampicillin, 19.3% (17/86) were resistant to tetracycline antibiotics, and 13.9% (12/86) were resistant to streptomycin antibiotics. The resistance test results showed that multidrug resistance in Escherichia coli bacteria taken from cat anal swabs was 6.9% (6/86).

Same-day identification and genotypic antibiotic resistance testing of Mycobacterium tuberculosis complex and non-tuberculous mycobacteria from positive blood culture bottles – a proof of principle assessment

Background and Aims: patients suffering from systemic mycobacterial spread are at high risk of unfavorable clinical outcomes. Rapid microbiological diagnosis, however, is complicated due to the very slow cultural growth of mycobacteria. To facilitate the diagnostic workflow, we assessed a workflow allowing mass spectrometry-based identification and molecular resistance testing of mycobacteria directly from blood culture pellets. Materials and Methods: for this study, 50 blood cultures spiked with n=10 Mycobacterium tuberculosis (MTC) isolates and n=40 isolates belonging to 12 other species of non-tuberculous mycobacteria (n=13 M. abscessus complex, n=5 M. avium, n=3 M. chimaera, n=5 M. fortuitum, n=5 M. intracellulare, n=2 M. lentiflavum and n=2 M. mucogenicum, n=1 for each one of the species M. elephantis, M. hassiacum, M. marseillense, M. nebraskense and M. parascrofulaceum) were used next to two clinical cases of a disseminated infection in HIV patients. Results: the application of the MBT Sepsityper® kit allowed the correct species level identification by applying mass spectrometry as well as correct molecular resistance testing results as compared to the diagnostic reference approach applied with mycobacterial culture material. Conclusions: in conclusion, the results provide a proof-of-principle of the suitability of the assessed potential workflow in order to achieve a shortened time-to-result for the diagnosis of systemic mycobacterial infections. Future studies in high endemicity settings are desirable to assess the clinical applicability and impact of such a shortened workflow.

Evaluation of the Mechanical and Electrical Properties of Multistage Drawn Copper-Clad Aluminum Wire After Annealing Process

This study evaluates the mechanical and electrical properties of copper-clad aluminum (CCA) wire prepared with a total cross-section reduction of 89% through a multistage cold drawing process and subjected to annealing at various temperatures. In addition to the CCA wire, individual samples of oxygen-free copper and aluminum, drawn with a cross-sectional reduction of 50%, were annealed under the same temperature conditions to enable a comparative analysis. Tensile tests for strength and elongation measurements were conducted, while electrical conductivity was assessed through resistivity tests. SEM and EDS analyses were performed to examine the diffusion thickness and the composition of intermetallic compounds generated at the Al/Cu interface of CCA wire. The tensile strength of the CCA wire decreased and its elongation increased up to 250 °C, after which were maintained. As the annealing temperature increased, intermetallic compound layers of Al2Cu, AlCu, and Al4Cu9 were formed at the Al/Cu interface of the CCA wire, and their thickness increased. Electrical conductivity reaches a maximum at 200 °C and then continuously decreases, showing a negative linear correlation with an increase in the diffusion layer thickness of intermetallic compounds. The study confirmed that cold-drawn CCA wire achieves stable mechanical properties and maximum electrical conductivity at the optimal annealing temperature.

Catalytic Ozonation of Formaldehyde with an Oxygen-Vacancy-Rich MnOx/γ-Al2O3 Catalyst at Room Temperature

Formaldehyde (HCHO) is known as one of the important indoor organic pollutants. How to remove and decompose the low concentration of formaldehyde at room temperature is important for indoor environments. Catalytic ozonation is an efficient method to thoroughly remove HCHO at room temperature, with high efficiency and few byproducts. A series of MnOx/γ-Al2O3 catalysts were prepared in this work via the impregnation method and treated with different reagents (acid, alkali, and H2O2) to evaluate their catalytic activity for HCHO removal. The results showed that MnAl-II (acid treatment) performed well in activity tests, reaching a nearly 100% HCHO conversion at an O3/HCHO of 2.0 and attaining a CO2 selectivity of above 95% at an O3/HCHO of 3.0 at 30 °C, with almost no ozone residual existing. The larger specific surface area, abundant oxygen vacancies, and higher number of acid sites contributed to the excellent performance of MnAl-II. Stability and H2O resistance tests of MnAl-II were also conducted. To reveal the intermediate product formation and further investigate the reaction mechanism of HCHO ozonation, in-situ DRIFTS measurement was carried out combined with DFT calculations.

Comprehensive pathogen identification and antimicrobial resistance prediction from positive blood cultures using nanopore sequencing technology

BackgroundBlood cultures are essential for diagnosing bloodstream infections, but current phenotypic tests for antimicrobial resistance (AMR) provide limited information. Oxford Nanopore Technologies introduces nanopore sequencing with adaptive sampling, capable of real-time host genome depletion, yet its application directly from blood cultures remains unexplored. This study aimed to identify pathogens and predict AMR using nanopore sequencing.MethodsIn this cross-sectional genomic study, 458 positive blood cultures from bloodstream infection patients in central Taiwan were analyzed. Parallel experiments involved routine microbiologic tests and nanopore sequencing with a 15-h run. A bioinformatic pipeline was proposed to analyze the real-time sequencing reads. Subsequently, a comparative analysis was performed to evaluate the performance of species identification and AMR prediction.ResultsThe pipeline identified 76 species, with 88 Escherichia coli, 74 Klebsiella pneumoniae, 43 Staphylococcus aureus, and 9 Candida samples. Novel species were also discovered. Notably, precise species identification was achieved not only for monomicrobial infections but also for polymicrobial infections, which was detected in 23 samples and further confirmed by full-length 16S rRNA amplicon sequencing. Using a modified ResFinder database, AMR predictions showed a categorical agreement rate exceeding 90% (3799/4195) for monomicrobial infections, with minimal very major errors observed for K. pneumoniae (2/186, 1.1%) and S. aureus (1/90, 1.1%).ConclusionsNanopore sequencing with adaptive sampling can directly analyze positive blood cultures, facilitating pathogen detection, AMR prediction, and outbreak investigation. Integrating nanopore sequencing into clinical practices signifies a revolutionary advancement in managing bloodstream infections, offering an effective antimicrobial stewardship strategy, and improving patient outcomes.

Enhancing the Mechanical and Fire-Resistant Properties of GFRP Composite using Boric Acid and Sodium Silicate Fillers

This study investigates the effects of Boric Acid (BA) , H3BO3, and Sodium Silicate (SS), Na2SiO3, as single fillers on the mechanical and fire-resistant properties of Glass Fiber Reinforced Polymer (GFRP) composites. Various compositions of BA and SS were incorporated into the GFRP matrix, and the resulting composites were analyzed using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermo-Gravimetric Analysis (TGA), and Differential Thermal Analysis (DTA). The results demonstrate that BA significantly enhances the amorphous structure and mechanical strength of GFRP composites, with optimal performance at 10% BA content. In contrast, SS improves thermal stability but reduces mechanical strength at higher concentrations due to agglomeration. Fire resistance testing revealed that both fillers increase the ignition time and decrease the burning rate, with BA exhibiting superior performance. These findings suggest that BA is a more effective filler for improving the mechanical and fire-resistant properties of GFRP composites, while SS can serve as a complementary additive to enhance thermal stability.

The Impact of Adherence Counselling Incorporating a Point of Care Urine Tenofovir Assay on Virologic Suppression among Individuals Failing Tenofovir-Lamivudine-Dolutegravir: A Pre - Post intervention Study.

To examine if point-of-care urine tenofovir testing-informed counseling could be used to improve virologic suppression (VS) among participants with virologic failure (VF) after ≥1 prior round of enhanced adherence counseling (EAC). Participants were enrolled from 42 clinics across Namibia. At each monthly medication pick-up, participants completed the point-of-care urine test and received EAC informed by this testing (EAC+). If VS was not achieved after 3 months of EAC+, up to 3 additional rounds of EAC+ were provided, with resistance testing at month (M)9. Of 310 potentially-eligible participants across 42 clinics in Namibia, we enrolled 211 participants with VF (median age 33 years, 61% female); 195 reached M3 defined as receiving EAC+ and follow-up viral load testing; 169 achieved VS within M3 (87%, p<0.001) and 97% by M9 (181/186) compared to 40% (22/55) prior to the intervention (p<0.001). Resistance testing was performed in five remaining participants with VF at M9, of whom 1/5 (20%) developed dolutegravir resistance. The urine tenofovir assay when incorporated into adherence counseling has potential to be a cost-effective intervention among participants failing tenofovir-based regimens, increasing VS to 97% in those failing TLD. Encouraging results of this pre-post intervention will be rigorously tested in a randomized trial.

Evaluation of fly ash-based geopolymer concrete incorporating coarse and fine recycled aggregates

Geopolymer Concrete (GC) is emerging as a promising material due to its lower carbon footprint compared to conventional Portland Cement (PC) concrete. One of the ways to further enhance the sustainability of GC is by incorporating Recycled Aggregates (RA). This study focuses on evaluating the performance of GC made with Coarse Recycled Aggregate (CRA) and Fine Recycled Aggregate (FRA). The mechanical property in terms of compressive strength and long-term durability properties, such as the Capillary Suction Test (CST), Initial Surface Absorption Test (ISAT), and acid attack test, were evaluated for all GC mixes. Ultrasonic Pulse Velocity (UPV) test and the electrical resistivity test, have also been done on all GC mixes. The results show that FRA beyond 25%, along with 50% CRA, is having an adverse impact on the long-term durability properties of GC. The GC mix with a combination of 50% CRA and 25% FRA shows at par compressive strength and electrical resistivity values relative to the Natural Aggregates (NA) GC. The findings from this study are expected to provide valuable insights into the optimal use of RA in GC and contribute to the broader goal of developing sustainable construction materials.

Study on the effect of nano-silica on the early-age strength and microstructure of cement paste mixed with calcium nitrite under negative temperature conditions

During construction at low temperatures, fresh concrete is susceptible to early freeze damage, which can permanently damage the concrete structure. Therefore, this study aimed to enhance the early-age strength and durability properties of the cement paste at −5 ℃ by incorporating calcium nitrite (CN) antifreeze and nano-silica (NS). First, the effects of CN and NS on the fresh properties of the cement paste were measured by setting time and bleeding rate tests. Subsequently, the mechanical properties and chloride content after salt solution erosion were tested for each group of specimens, and the change in slurry densification was further observed by ultrasonic pulse velocity and resistivity tests. Finally, the hydration products and microstructure of the specimens were analyzed using XRD and SEM tests. The results showed that the addition of CN and NS could reduce the setting time of cement paste and avoid the bleeding phenomenon of cement paste under negative temperature environment. The decrease in curing temperature and the use of NS both inhibited the promotion of C3A hydration by nitrite ions, which led to a decrease in nitrite-AFm content. However, NS can compensate for the reduced nitrite-AFm content by promoting the production of hydrated C-S-H through nucleation and pozzolanic effects. Ultimately, the strength and resistance of the slurry to chloride erosion are improved.

Comportamento higrotérmico de tijolo cerâmico de olaria do sul do Brasil

Abstract The presence of moisture in buildings can lead to pathological manifestations, and the behavior of materials when exposed to various conditions can be predicted through computational simulations. For this purpose, the hygrothermal characteristics of building elements are paramount. In Brazil, there is a gap in studies on the hygrothermal properties of materials, compromising simulations. This article discusses the possibilities of using European data in simulating moisture transport in ceramic brick walls in the southern region of Rio Grande do Sul, Brazil. The results were generated by comparing hygrothermal simulations with WUFI Pro 6.5 using the simulation program database with data collected from laboratory tests on ceramic bricks from a southern Brazilian brickyard. Tests for water vapor diffusion resistance, water absorption, and hygroscopic curves were conducted. Although both situations led to the growth of filamentous fungi, experimental data led to3% lower values compared to database results. Regarding surface condensation, a likely higher occurrence was observed when using laboratory test data.

Waterborne superhydrophobic bio-epoxy coating on Al alloy for corrosion-resistant and self-cleaning applications

Aluminum (Al) and its alloys are important engineering materials in modern industry due to their numerous advantages and have been widely used in various fields, including aerospace, marine, civilian industries and so on. However, they are prone to corrosion and contamination under harsh environmental conditions, particularly in marine environment when exposed to salty water or moisture for a long time, which can adversely affect their aesthetic appearance and desired functionalities or even cause economic losses and serious accidents. To prevent or delay the corrosion, the hydrophilic nature of Al and its alloy surfaces can be transformed to be hydrophobic or superhydrophobic. In this study, we reported an environment-friendly waterborne superhydrophobic bio-epoxy coating (WSBC) without using volatile solvents. The coating is composed of bio-epoxy resin, nano silica, silane coupling agent as well as hydrophobic curing agent, and applied by spin method on Al alloy substrates. The surface morphology and roughness were characterized by a field emission scanning electron microscope (FESEM) and an atomic force microscope (AFM). The WSBC with 22.2 wt% nano silica loading without considering the solvent of DI water displays a water contact angle (CA) as high as 165.8 ± 3.3° and a sliding angle (SA) as low as 5.3 ± 2.5°. Electrochemical measurement results showed that the as-prepared WSBC has a significant shift from −1.160 V to −0.708 V in the corrosion potential (Ecorr) and 3 orders of magnitude decrease in the corrosion current density (Jcorr), indicating excellent corrosion resistance. The WSBC was further proven to function well after immersion in deionized (DI) water and common organic solvents including ethanol and acetone for 48 h, and weathering resistance test. In addition, the as-prepared WSBC also showed good self-cleaning performance. The developed coating is green and no harm to human health and environment. The facile and eco-friendly process is of great importance for many industrial applications which can provide an attractive way towards anti-wetting surfaces for corrosion protection and self-cleaning effect on a variety of engineering substrates.

Comparative study of PS and PES and their sulfonated forms in antifouling behavior and rejection efficiency

In this study, novel hybrid ultrafiltration (UF) membranes were developed using polyethersulfone (PES), polysulfone (PS), and their sulfonated counterparts (SPES and SPS) to enhance water flux and antifouling properties. FTIR and XRD analyses validated the successful incorporation of sulfonate groups and structural changes, while SEM images revealed more porous and uniform membrane structures. Thermogravimetric analysis (TGA) showed enhanced thermal stability for the sulfonated membranes. Mechanical property evaluations demonstrated that the sulfonated membranes maintained good tensile strength and flexibility. Water uptake and porosity measurements indicated increased hydrophilicity and porosity for SPES and SPS membranes compared to their pristine forms. The pure water flux of SPES (130 L/m2·h) is significantly higher compared to PES (110 L/m2·h). The sulfonated membranes (SPS and SPES) exhibit significantly enhanced antifouling properties, as demonstrated by the improved flux recovery ratios (FRR) for SA, BSA, and HA compared to their non-sulfonated counterparts (PS and PES), reaching up to 75 % for SPES. The rejection performance for BSA, HA, and SA solutions showed that SPES membranes achieved 95 %, 90 %, and 92 % rejection rates, respectively, compared to 80 %, 75 %, and 70 % for PS membranes. Fouling resistance tests using BSA, HA, and SA solutions showed that SPES and SPS membranes had significantly higher flux and lower fouling tendencies.