Determination of essential elements and trace heavy metals in agricrops by photoneutron activation analysis and X-ray fluorescence methods

Applicative researches in the field of environmental protection like X-ray fluorescence analysis, neutron activation analysis, and other methods, present real increasing importance related to the climate changes that can be observed nowadays. Scientific methods will enter step by step in our life, first of all, due to the accelerated technological development and due to the objective motivations of environmental monitoring necessary to take correct measures for the preservation and protection of nature on the Earth. Determination of some inorganic components, mainly heavy metals, in agricultural crops, is frequently required in health-related environmental studies, due to the high toxicity of trace amounts of such elements for the human organism. The main sources of trace elements to agricrops are their growing media, as soil-water-air ecosystem from which those nutrients are taken up by the root to the foliage. The goal of the present research was to determine the extent to which industrial inorganic pollutants are transferred to the crops. It was achieved by using multielement techniques as photon neutron activation method and X-ray fluorescence methods and statistical modeling in order to determine levels, pathways, and fate of toxic and non-toxic bioactive elements in selected agricrops along with the root soil. Some of the experimental trace metal values exceeded the threshold established by Romanian and EU regulations to protect vegetation and explain the estimated significant crop losses. Multivariate modeling by factor analysis and neural network simulation of the elemental concentration data showed always the component loaded with specific elements coming from industrial emissions. These kinds of studies are very requested regarding the vegetable meant for the human diet.

Single-molecule fluorescence vistas of how lipids regulate membrane proteins

The study of membrane proteins is undergoing a golden era, and we are gaining unprecedented knowledge on how this key group of proteins works. However, we still have only a basic understanding of how the chemical composition and the physical properties of lipid bilayers control the activity of membrane proteins. Single-molecule (SM) fluorescence methods can resolve sample heterogeneity, allowing to discriminate between the different molecular populations that biological systems often adopt. This short review highlights relevant examples of how SM fluorescence methodologies can illuminate the different ways in which lipids regulate the activity of membrane proteins. These studies are not limited to lipid molecules acting as ligands, but also consider how the physical properties of the bilayer can be determining factors on how membrane proteins function.

Study of Chemical Composition of Walnut Shell Coal

The article investigates the chemical composition of walnut shell coal by spectrographic and X-ray fluorescence methods. The composition of the ash content of walnut shell coal has been determined: Si, K, F, Ca, Mg, Fe, Na, Mn, Zn, Cu, I, Ba, As, Ni, etc. Carbon — 84–84.9%.

Optical sensor for the detection of mycotoxins

The methods of detection of mycotoxins in agricultural products have been analyzed. The advantages of using the fluorescence methods for the express diagnostics of the presence of mycotoxins in samples have been shown. The development of an optical biosensor, which allows the detection of mycotoxins in the field, has been presented. The principles of operation have been established, and the constructive solution of a sensor has been proposed. An electro-optical scheme for obtaining an information signal has been developed and tested. The particular attention has been paid to the choice of an element base of the proposed microsensor. The principles and procedure for its validation have been shown. The practical results of testing the developed technical solution have been presented. The achieved relative error in the linear approximation of the sensor conversion characteristics in the interval of concentrations 0…100 ppb at a temperature of 15…25 °С does not exceed 2%. The developed sensor can be used in agriculture for the express detection and evaluation of the mycotoxin contamination.

Enhancement of Recombinase-Aided Amplification (Raa) Assay by Betaine and Pullulan

In this research, nucleic acid amplification enhancers suitable for recombinase-aided amplification (RAA) assay were studied for the first time, and amplification of a long-fragment (509 bp) by the RAA assay was initially explored. Using recombinant plasmids and clinical samples, RAA fluorescence and basic methods were used to evaluate the efficacy. The fluorescence method was evaluated by threshold time (TT) and fluorescence value, and the basic method was interpreted by 2% agarose gel electrophoresis. Taking a previously established RAA assay for HPV18 as an example, we demonstrated that the addition of 0.2, 0.4, and 0.6 M betaine and 10% pullulan could enhance RAA. The new RAA assays with betaine and pullulan were called B-RAA and P-RAA, respectively. In the B-RAA and P-RAA fluorescence methods, TT values could be shortened by 1.72–2.32 and 2.60 minutes, respectively, and fluorescence values could be enhanced by 8847.25–9094.37 and 5250 mv, respectively. In the basic method, sensitivity could be increased by 10-fold. We successfully amplified a long-fragment of 509 bp in a P-RAA assay with a sensitivity of 102 copies/μL (compared with 103 copies/μL in the RAA assay). We thus conclude that betaine and pullulan are effective additives to enhance RAA assays.

Ratiometric Electrochemistry: Improving the Robustness, Reproducibility and Reliability of Biosensors

Electrochemical biosensors are an increasingly attractive option for the development of a novel analyte detection method, especially when integration within a point-of-use device is the overall objective. In this context, accuracy and sensitivity are not compromised when working with opaque samples as the electrical readout signal can be directly read by a device without the need for any signal transduction. However, electrochemical detection can be susceptible to substantial signal drift and increased signal error. This is most apparent when analysing complex mixtures and when using small, single-use, screen-printed electrodes. Over recent years, analytical scientists have taken inspiration from self-referencing ratiometric fluorescence methods to counteract these problems and have begun to develop ratiometric electrochemical protocols to improve sensor accuracy and reliability. This review will provide coverage of key developments in ratiometric electrochemical (bio)sensors, highlighting innovative assay design, and the experiments performed that challenge assay robustness and reliability.

Hierarchical dynamics in allostery following ATP hydrolysis monitored by single molecule FRET measurements and MD simulations

We report on a study that combines advanced fluorescence methods with molecular dynamics simulations to cover timescales from nanoseconds to milliseconds for a large protein, the chaperone Hsp90.

Overcoming the lithium analysis difficulties with a simple colorimetric/spectrophotometric method

ABSTRACT: Analytical determination of lithium ions is usually performed by atomic absorption and X-ray fluorescence methods. Chemical analysis based on polyfluoroporphyrin chromogenic methods is also being employed, specially for biological...