Search results for "Biological materials"

Electrochemical characterization of mangrove sediments: A proposal of new proxies for organic matter oxidation

2019

Abstract The voltammetric response of microparticulate deposits resulting from solvent evaporation of ethanolic extracts of mangrove sediments in contact with aqueous acetate buffer is hereby described. Dated sediment cores sampled from the Peruvian mangrove system (“Manglares de Tumbes” National Sanctuary) presented voltammetric responses dominated by oxidative signals of organic components that exhibit significant variations depending on the depth. Voltammetric data allowed for the definition of electrochemical indexes representative of the electrochemically oxidable organic matter fraction. These electrochemical indexes were fEAOM (for the total amount of organic matter being electrochem…

Modelling hydrolysis: Simultaneous versus sequential biodegradation of the hydrolysable fractions

2018

Hydrolysis is considered the limiting step during solid waste anaerobic digestion (including co-digestion of sludge and biosolids). Mechanisms of hydrolysis are mechanistically not well understood with detrimental impact on model predictive capability. The common approach to multiple substrates is to consider simultaneous degradation of the substrates. This may not have the capacity to separate the different kinetics. Sequential degradation of substrates is theoretically supported by microbial capacity and the composite nature of substrates (bioaccessibility concept). However, this has not been experimentally assessed. Sequential chemical fractionation has been successfully used to define i…

A comparative molecular dynamics-phase-field modeling approach to brittle fracture

2016

Abstract In this work, a novel comparative method for highly brittle materials such as aragonite crystals is proposed, which provides an efficient and accurate in-sight understanding for multi-scale fracture modeling. In particular, physically-motivated molecular dynamics (MD) simulations are performed to model quasi-static brittle crack propagation on the nano-scale and followingly compared to macroscopic modeling of fracture using the phase-field modeling (PFM) technique. A link between the two modeling schemes is later proposed by deriving PFM parameters from the MD atomistic simulations. Thus, in this combined approach, MD simulations provide a more realistic meaning and physical estima…

Eine quantitative Bestimmungsmethode des Uracilgehaltes biologischen Materials im Nanogramm-Bereich mit Hilfe der Hochdruck-Flüssigchromatografie / A…

1974

Abstract A method is described for the estimation of the uracil content in biological materials by means of high-pressure liquid chromatography. Hydrolysis of the tissues and total liberation of RNA bases are carried out in 70% perchloric acid. Less than 1 mg of the materials are needed for analysis. A pre-purification of the hydrolyzates is carried out by anion-exchange chromatography. Recoveries are estimated by isotope dilution analysis with [2-14C] labelled uracil. The method is highly sensitive - about 6000 pmol of uracil content can at least be estimated quantitatively - and analysis time is short. In routine analysis a single sample needs 4 hours to be completed. When preparing sever…

Micro-determination of DNA in biological materials by gas-chromatographic and isotope dilution analysis of thymine content

1970

Challenges in the use of Near Infrared Spectroscopy for improving wood quality: A review

2018

Aims of study: Forestry-related companies require quality monitoring methods capable to pass a large number of samples. This review paper is dealing with the utilization of near infrared (NIR) technique for wood analysis.Area of study: We have a global point of view for NIR applications and characterization of different kind of wood species is considered.Material and methods: NIR spectroscopy is a fast, non-destructive technique, applicable to any biological material, demanding little or no sample preparation. NIR spectroscopy and multivariate analysis serve well in laboratories where the conditions are controlled. The main challenges to NIR spectroscopy technique in field conditions are mo…

Voltammetric determination of platinum in perfusate and blood: Preliminary data on pharmacokinetic study of arterial infusion with oxaliplatin

2012

Abstract Because Platinum Group Elements have found widespread use in catalytic converters in cars and as chemotherapeutic agent, interest in the development of reliable analytical methods is carried out in order to monitor these analita in humans to protect the citizen's health. Considering that information on the levels of many trace elements in biological matrices is scarce and for many non-essential elements, baseline levels in the population, and especially in those particularly exposed to the risk are lacking, in this paper we optimize an analytical method for biological matrices, using a voltammetric technique to measure the concentration of Pt in blood and perfusate. The amount of P…