Papers by Keyword: Sample Preparation

Abstract: The preparation of metallographic samples remains a crucial aspect of microstructural analysis, especially with the continuous development of advanced materials and imaging techniques. Despite its significance, sample preparation is often underestimated, yet achieving a surface with minimal structural distortion is essential for accurate microstructure evaluation and data interpretation. This study aimed to optimize steel sample preparation methods to obtain surfaces suitable for correlative imaging using multiple microscopic techniques, including modern scanning electron microscopy (SEM) with sample bias and electron backscatter diffraction (EBSD). The results demonstrate that specific contrast features observed in SEM can, in some cases, be qualitatively verified using EBSD. Furthermore, variations in SEM settings, such as lower landing energy, influence information depth, which in turn affects the accuracy of phase quantification, particularly when utilizing artificial intelligence-based methods.

Abstract: The main aim of this work is to develop an automated system for sample preparation. For the detection of small amounts of biological material, methods and procedures for concentration must be used. In this case, sample preparation refers to the concentration of bacteria in solutions. The problem of automated concentration of microbiological substances of low concentration in solution is discussed in more detail in this work. During sampling, volumes of approximately 100 mL are taken and processed. To achieve this goal, the construction of an automated system was planned and implemented. This system without contamination of the sample was implemented using a peristaltic pump, pinch valve, and air bubble detector. The influence of different system parameters has been investigated and the function of the system was tested for suitability in laboratory experiments. In addition, results from laboratory tests were evaluated. It was shown that a concentration of samples is possible with the help of a filter and backwash process. From this it is evident that an automated setup for this process should be aimed at, to make the procedure possible for non-specialized personal in this field. Furthermore, human error should additionally be minimized compared to all manual laboratory test. This study demonstrates such a system and shows the potential of filtering and backwashing of bacteria.

Abstract: In this paper, tests were performed by monitoring changes of strain amounts and their distribution by digital image correlation during static tensile testing of steel. The influence of different combination of speckles application on the sample surface (white speckles on the black sample surface and black speckles on the white sample surface) during cold deformation of steel was tested with the non-contacting digital image correlation. Strain amounts obtained by digital image correlation analysis of tested samples, with white on black and black on white painted speckle patterns, were compared. Different analysis for determining and monitoring strain amounts, provided by digital image correlation software, were used in this paper. The strain amounts were compared during cold deformation until the occurrence of sample fracture in both combinations of speckles application on the sample surface. Research has shown the importance of proper sample preparation for determination strain amounts and insignificant minor differences of strain amounts, between different sample preparations for digital image correlation, during cold deformation of tested steel.

Abstract: Molecularly Imprinted Polymer-Oleic Acid (MIPOA) and Molecularly Imprinted Polymer-Palmitic Acid (MIPPA) were synthesized using oleic acid and palmitic acid as the templates; acetonitrile as the porogenic solvent; and allylthiourea as the monomer; and EDGMA as a cross-linker via bulk polymerization. The non-imprinted polymers (NIP) as a control were prepared with the same procedure, but with the absence of template molecule. The synthesized MIPs and NIP were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and the results showed the narrowing of –OH peak which shows that crosslinking has occurred. Field Emission Scanning Electron Microscope-Energy Dispersive X-Ray (FESEM-EDX) was used to analyze the composition of in both MIPs and NIP. The results yielded a composition of C, O, and S. This analysis corresponds to the composition of oleic acid and sulfuric acid as both templates contain -COOH group. These results suggested that the molecularly imprinted polymers can be employed as a potential adsorbent for the removal of oleic acid and palmitic acid from palm fatty acid distillate (PFAD) waste.

Abstract: Blood sampling as well as sample preparation are time consuming and requires a strict procedure, which is generally performed by medical trained personal. Not carrying out the procedure correctly could result in an infection of the patient or contamination of the sample itself. These limitations should be especially considered in case of pandemic outbreaks. In order to handle such a high number of patients a novel sample preparation system paired with modern blood sampling procedure is necessary. For this reason, a new device for blood sampling and preparation is designed containing an integrated microfluidic system. The fabrication is carried out by utilizing micro moulding of PDMS as well as micro milling. A first set of initial experiments as part of a first-generation study shows promising results. However, further steps of optimisation considering flow time and preparation cycle are part of a second-generation study.

Abstract: The sample preparation for biological and chemical probes involves following a strict workflow to eliminate any contamination to the sample beforehand. Furthermore, it is time consuming and must be carried out by trained personnel such as a nurse or other supervisors, making it therefore expensive. The development of novel sample preparation techniques paired with modern sample analysis systems is focused on improving the operability while keeping a constant quality of results. This is important to analyse samples, which cannot be determined with current screening conditions. The analysis of analytes is required to receive a more detailed picture of the patient and to fully understand its complexity. Possible samples for in-depth analysis of chemical origin can be cholesterol or glucose. More complex samples, such as blood or saliva, require a sophisticated system, which analyses the samples for their individual compounds.

Abstract: Sample preparation of metastable austenitic-ferritic steels can have a significant effect on the apparent microstructure due to the transformation of austenite to martensite (γ - α'). As a result, these steels often have a complex microstructure with ferrite and martensite, which have relatively similar crystal structures, making it very difficult to analyse. However, the quantitative analysis of such microstructures and the effect of the sample preparation are very important for the further study of the steel. In this research, the effect of sample preparation in metastable austenitic-ferritic stainless steel was studied by using three different sample preparation methods. In addition to conventional mechanical etching with colloidical silica and electropolishing, focused ion beam (FIB) milling was used to create an optimal sample surface to be further analysed with electron backscatter diffraction (EBSD). Micrographs were obtained from each sample before and after sample preparation using field emission scanning electron microscopy (FESEM) and laser scanning confocal microscopy (LSCM), and the microstructure was analysed using EBSD. The surface flatness required for good EBSD analysis was significantly better using FIB milling than mechanical polishing, while electropolishing results in the greatest topography and an arched sample surface. The amount of martensite was found to be dependent on the sample preparation: least martensite was formed during electropolishing, while surprisingly mechanical polishing and FIB milling resulted in equal amounts of martensite.

Abstract: A novel TEM sample preparation method is proposed in this paper, which utilizes magnetorheological finishing to thin TEM sample. It can effectively reduce subsurface damage caused by mechanical lapping. A magnetorheological polishing tool is designed to meet TEM sample thinning requirements. Thinning testis conducted on Φ3mm single crystal silicon. Polished surface is observed by using transmission electron microscope, and high-resolution microscopy image of single crystal silicon can be achieved.

Abstract: A fast and simple method to allow routine analysis of waste phosphors was developed and fully validated. Pb, Hg in waste fluorescent lamps phosphors (WFP) and Pb, Cd in waste CRT phosphors (WCP) were quantified by inductively coupled plasma atomic emission spectrometry (ICP-OES). Analytical conditions, including choice of analytical spectral lines, sample dissolution methods and many other standards, were studied. Wavelengths of 220.353, 228.802, and 184.886 nm were selected as analytical lines for determination of Pb, Cd, and Hg respectively. Studies showed that, Nitric acid could be used for dissolving Cd and Hg, and alkali fusion method for Pb. Detection limits of Pb, Cd, and Hg found were 1.8, 0.3 and 3mg/kg respectively. The proposed method was used in determination of target elements in waste rare earth phosphors, giving values of recovery in the ranges of 96.5%-104%, 98.5%-105% for Pb, Hg in WFP, and 98%-104.5%, 98%-104.5% for Pb, Cd in WCP respectively, and values of RSD less than 8%. Also, influences by dilution factor, coexisting elements and HNO3 Concentration etc. were discussed in the paper.

Abstract: The turbine wheel is the most affected element in passenger car turbochargers. In order to meet the requirements for the high temperature corrosion, vibrations and the mechanical resistance in the oxidizing environment of the exhaust gases, the turbine wheel is produced from polycrystalline nickel based superalloys, Inconel 713C in the as-cast condition. In this work the methods and results of turbine wheel failure analysis are presented. For this type of research, correlative microscopy, light microscope Axio Imager Z2m (LM), scanning electron microscope Zeiss Ultra Plus with field emission (FESEM) equipped with EDX detector and stereoscopic microscope were used. The results of this work suggest that the Inconel 713C turbine wheel was damaged by two factors: fatigue cracking at low frequencies and grain boundaries oxidation.