Crystallization in Zirconia Film Nano-Layered with Silica

Gravitational waves are detected using resonant optical cavity interferometers. The mirror coatings’ inherent thermal noise and photon scattering limit sensitivity. Crystals within the reflective coating may be responsible for either or both noise sources. In this study, we explored crystallization reduction in zirconia through nano-layering with silica. We used X-ray diffraction (XRD) to monitor crystal growth between successive annealing cycles. We observed crystal formation at higher temperatures in thinner zirconia layers, indicating that silica is a successful inhibitor of crystal growth. However, the thinnest barriers break down at high temperatures, thus allowing crystal growth beyond each nano-layer. In addition, in samples with thicker zirconia layers, we observe that crystallization saturates with a significant portion of amorphous material remaining.

Assessment of Maximum Sensitivity of Acoustic Emission Technique

Knowledge of the ultimate sensitivity of the acoustic emission (AE) method is useful in studies of the mechanisms of plastic deformation of the structure, the formation and development of micro-, meso- and macro-cracks, as well as continuous processes, such as the outflow of liquids and gases, friction and a number of others. Analysis of literary data on assessment of limit sensitivity at identification of AE sources was carried out. It has been shown that when using standard resonant piezoelectric transducers with a frequency bandwidth of 30 ± 10 kHz, the ultimate sensitivity is the fraction of the nanometer in the displacement of the surface of the object and the unit micron of the size of the microcrack during its formation and hopping development. When testing industrial facilities, in many cases the level of external noise is significantly higher, the detection of defects decreases and amounts to a fraction of a millimeter. However, an increase in the energy and amplitude of AE signals as the defect develops in the vast majority of cases leads to the fact that when a crack reaches dimensions that begin to threaten the strength of the monitored object, AE signals are reliably detected by the equipment. Knowledge of the maximum sensitivity of the AE method makes it possible to compare it with other NDT methods by this parameter.

Efecto antimicrobiano de la tunta (Solanum juzepczukii) sobre la Salmonella enterica subespecie enterica serovar Typhimurium

The objective of the study was to investigate the antimicrobial activity of tunta on Salmonella enterica subspecies enterica serovar Typhimurium. A natural isolate of this bacterium was used that was resistant to chloramphenicol. The experiment required the preparation of a standard solution of 0,8 g / ml of tunta extract. The Kirby Bauer technique was used for the antimicrobial evaluation of the tests and the Duraffourd scale to measure the level of sensitivity. Resulting, for the ten technical repetitions of the experimental group, an average halo of 10,40 mm and a standard deviation of 0,63 of DHI (level of limit sensitivity, according to said scale). In conclusion, our work shows evidence that tunta has an antimicrobial effect at a borderline sensitivity level on Salmonella enterica subspecies enterica serovar Typhimurium. After more in-depth research, this derivative of Solanum Jueepczukii could become an alternative for the development of antibiotics of natural origin and allow a sustainable development of Andean cultures.

Application of Graphene-Based Materials for Detection of Nitrate and Nitrite in Water—A Review

Nitrite and nitrate are widely found in various water environments but the potential toxicity of nitrite and nitrate poses a great threat to human health. Recently, many methods have been developed to detect nitrate and nitrite in water. One of them is to use graphene-based materials. Graphene is a two-dimensional carbon nano-material with sp2 hybrid orbital, which has a large surface area and excellent conductivity and electron transfer ability. It is widely used for modifying electrodes for electrochemical sensors. Graphene based electrochemical sensors have the advantages of being low cost, effective and efficient for nitrite and nitrate detection. This paper reviews the application of graphene-based nanomaterials for electrochemical detection of nitrate and nitrite in water. The properties and advantages of the electrodes were modified by graphene, graphene oxide and reduced graphene oxide nanocomposite in the development of nitrite sensors are discussed in detail. Based on the review, the paper summarizes the working conditions and performance of different sensors, including working potential, pH, detection range, detection limit, sensitivity, reproducibility, repeatability and long-term stability. Furthermore, the challenges and suggestions for future research on the application of graphene-based nanocomposite electrochemical sensors for nitrite detection are also highlighted.

VERIFIKASI PENENTUAN ANGKA BAKTERI Escherichia coli PADA SAMPEL YANG DI-SPIKE MENGGUNAKAN METODE COLONY FORMING UNIT

The water that must be drunk is healthy water that meets the requirements of Bacteriology, Chemistry, Radioactivity and Physicality based on Republic of Indonesia Minister of Health Regulation No: 492 / MENKES / PER / IV / 2010 concerning the requirements and supervision of clean water quality which includes physical requirements which are odorless, not colored and tasteless, where for the Coliform value is 0/100 mL. Escherichia coli is a fecal coliform bacterium and an indicator of the quality of drinking water because its presence in water indicates that the water is contaminated by feces. The aim of this study was to determine the value of accuracy, precision, detection limit, sensitivity and specificity of the calculated numbers of Escherichia coli bacteria from spike samples using the CFU method with agar chromocult media. The results of the bacterial results obtained on accuracy parameters were 229.33%, precision ie 26.35%, LOD which was 13.85 CFU / ml, LOQ ie 138.54 CFU / ml, and Specificity of 0%. Based on the results of verification of bacterial numbers obtained from the results of the accuracy test, precision that is not within the range of general requirements indicates that the method cannot be valid to use factors that affect high dilution, rapid bacterial growth rate, adequate nutrition and observer vision, whereas specificity indicate that chromocult coliform is very specific to Escherichia coli.

Indicator Layers Based on Ethylene-Vinyl Acetate Copolymer (EVA) and Dicyanovinyl Azobenzene Dyes for Fast and Selective Evaluation of Vaporous Biogenic Amines

The article presents naked-eye methods for fast, sensitive, and selective detection of isopentylamine and cadaverine vapours based on 4-N,N-dioctylamino-4′-dicyanovinylazobenzene (CR-528) and 4-N,N-dioctylamino-2′-nitro-4′-dicyanovinylazobenzene (CR-555) dyes immobilized in ethylene-vinyl acetate copolymer (EVA). The reaction of CR-528/EVA and CR-555/EVA indicator layers with isopentylamine vapours caused a vivid colour change from pink/purple to yellow/orange-yellow. Additionally, CR-555/EVA showed colour changes upon exposure to cadaverine. The colour changes were analysed by ultraviolet–visible (UV/VIS) molecular absorption spectroscopy for amine quantification, and the method was partially validated for the detection limit, sensitivity, and linear concentration range. The lowest detection limits were reached with CR-555/EVA indicator layers (0.41 ppm for isopentylamine and 1.80 ppm for cadaverine). The indicator layers based on EVA and dicyanovinyl azobenzene dyes complement the existing library of colorimetric probes for the detection of biogenic amines and show great potential for food quality control.

Venomous Arachnid Diagnostic Assays, Lessons from Past Attempts

Diagnostic tests for arachnid accidents remain unavailable for patients and clinicians. Together with snakes, these accidents are still a global medical concern, and are recognized as neglected tropical issues. Due to arachnid toxins’ fast mechanism of action, quick detection and quantification of venom is required to accelerate treatment decisions, rationalize therapy, and reduce costs and patient risks. This review aims to understand the current limitations for arachnid venom identification and quantification in biological samples. We benchmarked the already existing initiatives regarding test requirements (sample or biomarkers of choice), performances (time, detection limit, sensitivity and specificity) and their validation (on animal models or on samples from envenomed humans). Our analysis outlines unmet needs for improving diagnosis and consequently treatment of arachnid accidents. Hence, based on lessons from past attempts, we propose a road map for raising best practice guidelines, leading to recommendations for future progress in the development of arachnid diagnostic assays.

Comparison of four functionalization methods of gold nanoparticles for enhancing the enzyme-linked immunosorbent assay (ELISA)

The enzyme-linked immunosorbent assay (ELISA) technique is based on the specific recognition ability of the molecular structure of an antigen (epitope) by an antibody and is likely the most important diagnostic technique used today in bioscience. With this methodology, it is possible to diagnose illness, allergies, alimentary fraud, and even to detect small molecules such as toxins, pesticides, heavy metals, etc. For this reason, any procedures that improve the detection limit, sensitivity or reduce the analysis time could have an important impact in several fields. In this respect, many methods have been developed for improving the technique, ranging from fluorescence substrates to methods for increasing the number of enzyme molecules involved in the detection such as the biotin–streptavidin method. In this context, nanotechnology has offered a significant number of proposed solutions, mainly based on the functionalization of nanoparticles from gold to carbon which could be used as antibody carriers as well as reporter enzymes like peroxidase. However, few works have focused on the study of best practices for nanoparticle functionalization for ELISA enhancement. In this work, we use 20 nm gold nanoparticles (AuNPs) as a vehicle for secondary antibodies and peroxidase (HRP). The design of experiments technique (DOE) and four different methods for biomolecule loading were compared using a rabbit IgG/goat anti-rabbit IgG ELISA model (adsorption, directional, covalent and a combination thereof). As a result, AuNP probes prepared by direct adsorption were the most effective method. AuNPs probes were then used to detect gliadin, one of the main components of wheat gluten, the protein composite that causes celiac disease. With this optimized approach, our data showed a sensitivity increase of at least five times and a lower detection limit with respect to a standard ELISA of at least three times. Additionally, the assay time was remarkably decreased.