Small Volume Of Material Research Articles

Nanoscale Spatially Resolved Mapping of Uranium Enrichment

Spatially resolved analysis of uranium (U) isotopes in small volumes of actinide-bearing materials is critical for a variety of technical disciplines, including earth and planetary sciences, environmental monitoring, bioremediation, and the nuclear fuel cycle. However, achieving subnanometer-scale spatial resolution for such isotopic analysis is currently a challenge. By using atom probe tomography—a three-dimensional nanoscale characterisation technique—we demonstrate unprecedented nanoscale mapping of U isotopic enrichment with high sensitivity across various microstructural interfaces within small volumes (~100 nm3) of depleted and low-enriched U alloyed with 10 wt% molybdenum that has different nominal enrichments of 0.20 and 19.75% 235U, respectively. We map enrichment in various morphologies of a U carbide phase, the adjacent γ-UMo matrix, and across interfaces (e.g., carbide/matrix, grain boundary). Results indicate the U carbides were formed during casting, rather than retained from either highly enriched or depleted U feedstock materials. The approach presented here can be applied to study nanoscale variations of isotopic abundances in the broad class of actinide-bearing materials, providing unique insights into their origins and thermomechanical processing routes.

A Survey of Nanoindentation Studies on HPT‐Processed Materials

The development of high‐pressure torsion (HPT) processing has increased the possibility for achieving significant grain refinement, which leads to a material's ability to produce ultrafine‐grained or nanocrystalline materials having enhanced strength without a large expense of ductility at room temperature. Since the applied strain is locally changed across the sample disc during HPT, the microstructure and thus mechanical properties vary within the disc. Recently, as a promising tool for characterizing the mechanical behavior of the local regions within the disc, the nanoindentation technique becomes widely used mainly due to its simple and easy testing procedures and the requirement of only small volume of material. The nanoindentation technique provides important clues to better understand the relation between microstructural refinement and mechanical property enhancement of the HPT‐processed materials. Here, the nanoindentation studies performed on various HPT‐processed materials are reviewed with focus on a variety of micromechanical properties that can be estimated by nanoindentation and the interesting results are reported in the available literature.

Nanoscale Spatially Resolved Mapping of Uranium Enrichment in Actinide-Bearing Materials

Spatially resolved analysis of uranium isotopes in small volumes of actinide-bearing materials is critical for a variety of technical disciplines, including earth and planetary sciences, environmental monitoring, bioremediation, and the nuclear fuel cycle. However, achieving sub-nanometer scale spatial resolution for such isotopic analysis is currently a challenge. By using atom probe tomography, a three dimensional nanoscale characterization technique, we demonstrate unprecidented nanoscale mapping of uranium isotopic enrichment with high sensitivity across various microstructural interfaces within small volumes (100 nm3) of depleted and low enriched uranium alloyed with 10 wt % molybdenum with different nominal enrichments of 0.20 and 19.75% 235U respectively. The approach presented here can be applied to study nanoscale variations of isotopic abundances in the broad class of actinide-bearing materials, providing unique insights into their origin and thermo-mechanical processing routes.

Abstract 1621: Multiplex analysis of proteins for cancer diagnosis: A case study using ActivSignal technology

Abstract Pancreatic cancer is one of the deadliest types of cancer, killing over 50,000 each year in the US, and with a five-year survival rate below 8%. However, currently there are no reliable diagnostic tests for pancreatic cancer, and the great majority of cases are detected at a late stage, with bleak mortality rates as a result. The ActivSignal IPAD platform monitors activity of 26 cancer signaling pathways in multiplex, by examining phosphorylation status or expression of 70 protein targets. The technology utilizes pairs of antibodies per each protein target to ensure high specificity. These antibody pairs are carefully tested and selected. Detection will only take place if both antibodies in a pair bind to their specific target molecule during the analysis phase - avoiding false hits. The ActivSignal IPAD platform can be used to profile cell culture samples, tissues and different blood fractions. The IPAD assay requires a very small amount of sample. All these characteristics make it potentially adaptable for diagnostics, simultaneously profiling multiple proteins targets. We have tested the assay in a preliminary analysis of human pancreatic cancer patients. Several control and pancreatic ductal adenocarcinoma (PDAC) blood samples were used for analysis. The assay can be performed on a very small volume of material, and 100 microliters of each sample was obtained from a collaborating academic medical center. The profiling was performed on 40 previously identified, relevant proteins. The comparison of Normal controls and PDAC patient samples gave a clear pattern that discriminated these two population groups with a great degree of certainty. Thus, giving a proof of concept that the assay can be used for diagnostic development for pancreatic cancer detection, an urgent unmet need. Citation Format: Ilya Alexandrov, Malcolm Mackenzie, Irina Brandina. Multiplex analysis of proteins for cancer diagnosis: A case study using ActivSignal technology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1621.

In Situ Method Correlating Raman Vibrational Characteristics to Chemical Expansion via Oxygen Nonstoichiometry of Perovskite Thin Films.

Effective integration of perovskite films into devices requires knowledge of their electro-chemomechanical properties. Raman spectroscopy is an excellent tool for probing such properties as the films' vibrational characteristics couple to the lattice volumetric changes during chemical expansion. While lattice volumetric changes are typically accessed by analyzing Raman shifts as a function of pressure, stress, or temperature, such methods can be impractical for thin films and do not capture information on chemical expansion. An in situ Raman spectroscopy technique using an electrochemical titration cell to change the oxygen nonstoichiometry of a model perovskite film, Sr(Ti,Fe)O3- y , is reported and the lattice vibrational properties are correlated to the material's chemical expansion. How to select an appropriate Raman vibrational mode to track the evolution in oxygen nonstoichiometry is discussed. Subsequently, the frequency of the oxygen stretching mode around Fe4+ is tracked, as it decreases during reduction as the material expands and increases during reoxidation as the material shrinks. This methodology of oxygen pumping and in situ Raman spectroscopy of oxide films enables future in operando measurements even for small material volumes, as is typical for applications of films as electrodes or electrolytes utilized in electrochemical energy conversion or memory devices.

Low-impedance superconducting microwave resonators for strong coupling to small magnetic mode volumes

Recent experiments on strongly coupled microwave and ferromagnetic resonance modes have focused on large volume bulk crystals such as yttrium iron garnet, typically of millimeter-scale dimensions. We extend these experiments to lower volumes of magnetic material by exploiting low-impedance lumped-element microwave resonators. The low impedance equates to a smaller magnetic mode volume, which allows us to couple to a smaller number of spins in the ferromagnet. Compared to previous experiments, we reduce the number of participating spins by two orders of magnitude, while maintaining the strength of the coupling rate. Strongly coupled devices with small volumes of magnetic material may allow the use of spin orbit torques, which require high current densities incompatible with existing structures.

The Influence of Process Parameters and Build Orientation on the Creep Behaviour of a Laser Powder Bed Fused Ni-based Superalloy for Aerospace Applications.

Additive Layer Manufacturing (ALM) is an innovative net shape manufacturing technology that offers the ability to produce highly intricate components not possible through traditional wrought and cast procedures. Consequently, the aerospace industry is becoming ever more attentive in exploiting such technology for the fabrication of nickel-based superalloys in an attempt to drive further advancements within the holistic gas turbine. Given this, the requirement for the mechanical characterisation of such material is rising in parallel, with limitations in the availability of material processed restricting conventional mechanical testing; particularly with the abundance of process parameters to evaluate. As such, the Small Punch Creep (SPC) test method has been deemed an effective tool to rank the elevated temperature performance of alloys processed through ALM, credited to the small volumes of material utilised in each test and the ability to sample material from discrete locations. In this research, the SPC test will be used to assess the influence of a number of key process variables on the mechanical performance of Laser Powder Bed Fused (LPBF) Ni-based superalloy CM247LC. This will also include an investigation into the influence of build orientation and post-build treatment on creep performance, whilst considering the structural integrity of the different experimental builds.

Dispersion of particulate in solvent cast magnetic thermoplastic polyurethane elastomer composites

Our research focuses on the processing of a thermoplastic magnetorheological elastomer (MRE) by solvent-casting a thermoplastic polyurethane (PU) elastomer with magnetic particulate for fused filament fabrication (FFF) applications. MREs are typically prepared by curing a thermoset silicone with magnetic particulate. Alternatively, thermoplastic MREs may be produced by the addition of magnetic particulate to a thermoplastic elastomer (TPE). FFF is a valuable manufacturing technique that allows for the creation of parts with inherent anisotropies. For the case of an MRE, FFF allows for the production of structures with tunable magnetic susceptibility along different axes. In these composites, the degree of particulate dispersion significantly affects the isotropy of material properties, which becomes increasingly important when small material volumes are used, such as in FFF. Incorporating solvent-casting as a method of producing polymer composites allows for greater control over the particulate addition method, leading to improved dispersion when compared to a polymer melt. For our purposes, composite films were produced in order to examine the effect of wet vs. dry addition of particulate on dispersion. The solvent used for casting was dimethylformamide (DMF). Preparation of polymer solutions included dissolution of PU in DMF to 20 w/v% followed by addition of the magnetic particulate. The particulates used were <150 µm iron powder and 2–4 µm magnetite powder. Composite solutions were made to concentrations of 20, 30, and 40 w/w% particulate to polymer by addition of either dry particulate or particulate pre-suspended in DMF. It was found that wet addition of particulate led to improvement in particulate agglomeration and magnetite particulate exhibited a significantly higher degree of agglomeration than iron.

Mechanical characterization of metals by small sampling size

Classical plasticity models permit to simulate accurately the macroscopic response of several metals. This ability supports the development of indirect material characterization methodologies based on non-destructive testing, potentially applied for the fast integrity assessment of structural components in operating conditions. In this context, reducing the sampling size mitigates the invasiveness of the experiments and improves the manageability of portable equipment, although the representativeness of the information collected from small material volumes may become an issue.This contribution focuses on the equivalence between the mechanical properties that can be inferred from metal sampling of typical dimensions of hundreds or dozens microns, corresponding to indentation tests carried out at maximum load differing by one order of magnitude. This topic is addressed by the comparison of the results gathered from experimental and numerical analyses of pipeline steel.

A critical assessment of the effect of indentation spacing on the measurement of hardness and modulus using instrumented indentation testing

With the advances in instrumented indentation systems and testing methodologies, high speed indentation mapping with indents that take less than a second is now possible. This can be gainfully used to measure the local mechanical properties of multi-phase alloys and small volumes of materials with high throughput, which brings into question the minimum spacing between indents required to prevent interactions from neighboring indents. In this study, extensive indentation experiments (~50,000) and finite element simulations are carried out for a wide range of materials to systematically determine the minimum spacing of indents. It was found that a minimum indent spacing of 10 times the indentation depth is sufficient to obtain accurate results for a Berkovich indenter. This is less than half of the commonly followed criteria of spacing the indents three times the lateral dimension (or 20 times the depth). Similar results were also found for other indenter geometries. It was found that non-overlapping plastic zones are not a requirement for determining the minimum indent spacing and the new criteria is rationalized by simple energy arguments. These results significantly enhance the capabilities of indentation mapping technique which is recently being used as a critical characterization tool for accelerating materials development.

Critical fuel property evaluation for potential gasoline and diesel biofuel blendstocks with low sample volume availability

We show that early-stage evaluation of critical fuel properties of new gasoline or diesel blendstock candidates can be accomplished using small volumes of material (<15 mL, compared to the ∼1 L typically required). The approach utilizes dilution and autoignition resistance via measurement of ignition delay to estimate the octane number or cetane number of a new blendstock. The ignition delay can be converted to a derived cetane number and derived octane number, providing a useful estimate of a critical combustion property. The results were validated against known compounds. Measurement of autoignition is important for evaluating blendstocks derived from biomass, where generating large volumes for initial evaluation may be prohibitively expensive. We have used this approach for several materials identified as having potential biological production pathways. Also, synthetic organic chemistry was employed to produce sufficient quantities of samples for autoignition measurement for those materials with no established biological scale-up route. The materials investigated were isomers of 5,5-dimethyl-2-ethyl-1,3-cyclopentadiene; branched alcohols and ketones; and hydrotreated terpenoid mixtures. Several candidates were identified with favorable fuel properties for either gasoline (derived research octane number greater than 90) or diesel (derived cetane number higher than 40).

Ultrastrong and High‐Stroke Wireless Soft Actuators through Liquid–Gas Phase Change

AbstractSoft actuators and robots, which depart from classical paradigms in rigid robot construction, increase the safety of robot–human and robot–environment interactions, bring superior adaptation capabilities, and extend the range of robotic operations to fragile and sensitive objects and environments. Pneumatic soft actuators are a key building block for soft robotics due to their inherent simplicity, high forces, and large strokes. However, pressure lines connected to large pumps, regulators, and valves put significant mobility limitations on these actuators. Recently, it has been demonstrated that by using phase changes of liquids, pumps can be eliminated in favor of on‐board pressure generation. Here, it is shown that power and control of soft actuators can be realized through phase change of liquids stimulated by inductor‐capacitor resonant receivers placed in an external magnetic field. The method requires no pumps, no external fluidic or electrical wiring, and no batteries on‐board, leading to the possibility of small and low profile wireless soft actuators and robots which can operate for long durations. The phase change enables ultrahigh forces and high strokes with a small volume of active material. An ultralow profile, strong and soft pneumatic bellows‐style actuator powered and controlled wirelessly demonstrates the potential of this technique.

Effect of Different Factors on Measured Values of Indentation Hardness of Interstitial Free Steel by Depth Sensing Indentation

Nanomechanical testing using depth sensing indentation (DSI) provides a straightforward solution for quantitatively characterizing each of phases in microstructure because it is very powerful technique for characterization of materials in small volumes. Measuring the local properties (indentation hardness HIT, indentation modulus EIT, indentation energy: total Wtotal, elastic Welast, plastic Wplast) of each microstructure component separately in multiphase materials gives information that is valuable for the development of new materials and for modelling. The mechanical properties of materials measured by DSI are affected by the experimental procedure, by the measurement conditions and factors which result from the material characteristics and device construction. We have to determine the effect of individual factors on the measurement in order to reach the repeatability and to allow the comparing the mechanical properties of the material. The aim of this investigation is to determine the measurement factors that affect indentation hardness of individual microstructural components and global mechanical properties of thin steel sheets. We investigated the factors which result from the material characteristics (crystallographic orientation of grain, grain boundary and anisotropy), preparation of the sample surface (roughness of sample surface) and method of measurement (pile-up, ISE).

Optimization of a Laser Ablation‐Single Collector‐Inductively Coupled Plasma‐Mass Spectrometer (Thermo Element 2) for Accurate, Precise, and Efficient Zircon U‐Th‐Pb Geochronology

AbstractMany applications specific to detrital mineral U‐Th‐Pb geochronology in the Earth sciences necessitate large numbers of age observations to be made from samples and require accurate and precise isotope measurements across wide dynamic ranges in elemental concentrations and signal intensities. This implies that the laser system and mass spectrometer cannot be tuned between individual analyses as to optimize measurements based on the isotope composition and concentrations of samples and that intensity matching between the unknowns to be dated and the reference material(s) used for fractionation correction is impossible to ensure. We describe methodologies for optimization of laser ablation‐single collector‐inductively coupled plasma‐mass spectrometer for the accurate determination of initial‐Pb‐corrected (using measured 204Pb) U‐Th‐Pb zircon ages, taking full advantage of the high sensitivity provided by the Thermo Element 2 ICP‐MS instruments fitted with a high‐performance low ultimate vacuum Jet interface. “We describe an approach that corrects for nonlinearity of the detector—the primary obstacle avoided with sample‐specific tuning—as well as element‐ and mass‐dependent fractionation and instrumental drift by using a suite of three zircon reference materials with known isotopic ratios from isotope dilution‐thermal ionization mass spectrometry measurements but with differing U and Pb concentrations.” This approach allows for (experimentally) determining an instrumental fractionation versus ion beam intensity curve used for standard‐sample bracketing, thus taking into consideration an important instrumental variable that is commonly ignored in most applications of U‐Pb dating using laser ablation‐single collector‐inductively coupled plasma‐mass spectrometer. We show that these methodologies yield uncertainties and age offsets typically better than ±2.0% for individual measurements of small (e.g., 10‐μm depth × 20‐μm diameter) volumes of material.

A method for site-specific and cryogenic specimen fabrication of liquid/solid interfaces for atom probe tomography

A site-specific, cryogenic, focused ion beam (FIB) method is presented for the preparation of atom probe tomography (APT) specimens from a frozen liquid/solid interface. As a practical example, the interface between water and a corroded boroaluminosilicate glass has been characterized by APT for the first time. The water/glass interface is preserved throughout specimen preparation by plunge freezing the corroding glass particles with the corrosion solution into slush nitrogen. Site-specific specimen preparation is enabled through a new approach to extract and mount a small volume of material using a cryogenically cooled FIB stage and micromanipulator. The prepared APT specimens are subsequently transferred from the FIB to APT under cryogenic and high-vacuum conditions using a novel FIB/APT transfer shuttle and home-built environmental transfer hub attached to the APT system. Particular focus is given to the technical methods for specimen fabrication under cryogenic conditions. Persistent challenges are discussed in addition to future opportunities for this new specimen preparation method.

Estimating mechanical properties from spherical indentation using Bayesian approaches

Instrumented indentation enables rapid characterization of mechanical behavior in small material volumes. The heterogeneous deformation fields beneath the indenter however make it difficult to infer the intrinsic constitutive properties (e.g., Young's modulus, yield strength). This inverse problem is addressed in the literature using optimization techniques that are generally unable to yield robust values for the properties of interest and cannot quantify property uncertainty. Furthermore, current approaches tend to exhibit very high sensitivity to the error definitions and the optimization techniques employed. In order to overcome these difficulties, we propose an alternate approach that involves two main steps: (i) Development of a Gaussian Process (or kriging) surrogate model using finite element models of spherical indentation, and (ii) inverse solution using a Bayesian framework and Markov Chain Monte Carlo sampling. These approaches are demonstrated using selected case studies.

High-Strain-Rate Material Behavior and Adiabatic Material Instability in Impact of Micron-Scale Al-6061 Particles

Impact of spherical particles onto a flat sapphire surface was investigated in 50-950 m/s impact speed range experimentally and theoretically. Material parameters of the bilinear Johnson–Cook model were determined based on comparison of deformed particle shapes from experiment and simulation. Effects of high-strain-rate plastic flow, heat generation due to plasticity, material damage, interfacial friction and heat transfer were modeled. Four distinct regions were identified inside the particle by analyzing temporal variation of material flow. A relatively small volume of material near the impact zone becomes unstable due to plasticity-induced heating, accompanied by severe drop in the flow stress for impact velocity that exceeds ~ 500 m/s. Outside of this region, flow stress is reduced due to temperature effects without the instability. Load carrying capacity of the material degrades and the material expands horizontally leading to jetting. The increase in overall plastic and frictional dissipation with impact velocity was found to be inherently lower than the increase in the kinetic energy at high speeds, leading to the instability. This work introduces a novel method to characterize HSR (109 s−1) material properties and also explains coupling between HSR material behavior and mechanics that lead to extreme deformation.

Load distribution by zones of frame sub-constructions of D2 class buggy racing car

In this paper, the authors consider the loading of the buggy car system under the most typical loading modes: the mode of approach of the front wheel to the obstacle, the mode of the rear wheel approach to the obstacle, the mode of diagonal loading, as well as the mode of twisting the frame around the longitudinal axis. For the convenience of analysis, the frame of the buggy car is divided into substructures, which, in turn, are divided into zones. For each of the zones of each sub-structure, the bar graph shows the proportion of the perceived load for each type of loading. The presented graphs make it easy to analyze overloaded and underloaded areas. For example, the rods of the upper zone of the rear subframe take a very small load, given the proportion of their volume. The reverse situation is observed in the sidewall region: in this zone much lower load is accounted for by a much smaller volume of material. At the same time, the areas of the floor and the middle perceive a load share, consistent with its volume fraction, which can be considered the optimal indicator of load distribution by volume. In this connection, it is important to note that the presented diagrams of the distribution of medium stresses over zones of substructures can be used as a starting point for optimizing of existing or for developing of such structures “from scratch”. Calculation of the load applied to the substructure was carried out by summing the average stresses on the elements constituting the considered subconstruction. In addition, with the help of the appropriate coefficient, an estimate was made to the correspondence of the proportion of the volume of the zone of a particular subconstruction to the proportion of the load applied to it. This information can then be used to optimize the design or used as a starting point for the design of similar structures. All the presented calculations were performed in the SolidWorks software using the finite element method.

Serum and Plasma Copy Number Detection Using Real-time PCR.

Serum and plasma cell free DNA (cfDNA) has been shown as an informative, non-invasive source of biomarkers for cancer diagnosis, prognosis, monitoring, and prediction of treatment resistance. Starting from the hypothesis that androgen receptor (AR) gene copy number (CN) gain is a frequent event in metastatic castration resistance prostate cancer (mCRPC), we propose to analyze this event in cfDNA as a potential predictive biomarker. We evaluated AR CN in cfDNA using 2 different real-time PCR assays and 2 reference genes (RNaseP and AGO1). DNA amount of 60 ng was used for each assay combination. AR CN gain was confirmed using Digital PCR as a more accurate method. CN variation analysis has already been demonstrated to be informative for the prediction of treatment resistance in the setting of mCRPC, but it could be useful also for other purposes in different patient settings. CN analysis on cfDNA has several advantages: it is non-invasive, rapid and easy to perform, and it starts from a small volume of serum or plasma material.

Microscale stirred-cell filtration for high-throughput evaluation of separation performance

Membrane filtration is a key separations technique in downstream bioprocessing applications: for a commercial bioprocess operation, 10–20 membrane-related steps are typically required. At the laboratory scale, the evaluation of membrane separation performance often involves a ‘stirred cell device’; however, this simple tool is poorly suited for conducting high-throughput studies of separation performance. Here, we designed a high-throughput stirred cell (HTSC) device which is ideally suited for conducting optimization studies, especially at the early stages of bioprocess development when small volumes of feed material are available. The HTSC allows for up to six filtration experiments to be run simultaneously with continuous mixing above each membrane facilitated by suspended magnetic stir elements. Using fluorescently-labeled dextrans as model biomolecules and commercial ultrafiltration membranes, it was shown that the HTSC device gave the same separation performance as a traditional stirred cell, but with the added benefits of operating at a faster pace (due to its parallel nature) and requiring nearly an order of magnitude lower sample volumes. Furthermore, the utility of the HTSC was demonstrated by concurrently evaluating the performance of four different ultrafiltration membranes for the same model biomolecule and the membrane selectivity for a mixture of two model bio-macromolecules.