Increasing Sample Volume Research Articles

Refining Sampling Efforts for Fish Diversity Assessment in Subtropical Urban Estuarine and Oceanic Waters Using Environmental DNA With Multiple Primers

ABSTRACTThe environmental DNA (eDNA) approach is an emerging tool for monitoring marine biodiversity. However, the sampling effort needs optimization according to the site characteristics and target taxonomic groups. In this study, we optimized the eDNA sampling effort in terms of sample volume and number of replicates to monitor the diversity of marine vertebrates (mainly fish) in Hong Kong's subtropical waters that show a gradient of estuarine to oceanic waters. To maximize detection, we used three pairs of metabarcoding primers (12S‐v5, MiFish‐U, and MiFish‐E). We compared vertebrate diversity in 78 water samples, ranging from 1 to 10 L, collected from oceanic and estuarine sites. Metabarcoding yielded a total of 140 vertebrate species, of which 18 were unique to the estuarine site, 66 unique to the oceanic site, and 56 shared between both sites. The detected species were predominantly ray‐finned fish (136 species), and the three primer pairs exhibited differential sensitivity toward different taxa, especially cartilaginous fish and cetaceans. Increasing sampling volume per replicate generally increased the total detected species, average species per replicate, and species coverage, and sampling 3 or 4 × 4 L represented the most efficient sampling effort for the estuarine and oceanic sites, respectively. The diversity analysis revealed that sampling >2 L per replicate reduced variability and improved diversity analysis. The results also showed that a larger sampling volume per replicate increased the probability of detecting endangered, indicator, invasive, and elusive species, with 4 L representing the most efficient volume. This study recommended sampling 4 L per replicate and 3 replicates for estuarine and 4 for oceanic sites, respectively for effectively monitoring marine fish in subtropical waters using the eDNA approach.

Estimation of self-absorption correction coefficients for gross-alpha activity measurements

Optimizing the sample volume is an important consideration while preparing planchets for measuring gross-alpha activity in environmental water samples. A higher sample volume results in increased thickness, which has a significant impact on gross-alpha activity measurements due to self-absorption in the samples. Moreover, while evaporating water samples on planchets to dryness, necessary precautions must be taken to prevent the loss of sample mass due to excessive heating. The present study represents a preliminary effort to estimate self-absorption correction coefficients and the efficiency of the detector, corrected for self-absorption, for estimating gross-alpha activity. The self-absorption correction coefficient versus sample volume is determined by performing gross alpha counting of different volumes of IAEA reference water samples. This is achieved through planchet preparations using varying quantities of water samples (ranging from 1 ml to 5 ml in steps of 1 ml, and from 10 ml to 20 ml in steps of 5 ml). The study also examines the effect of sample volume on the detector's efficiency for gross-alpha activity measurements. Additionally, the study highlights the impact of different drying methods in planchet preparations on gross-alpha activity measurements. The study reveals that the self-absorption correction coefficient decreases with increasing sample volume, indicating that larger sample volumes require more corrections for efficiency. Furthermore, it is observed that the efficiency, corrected for self-absorption, decreases with an increase in sample volume, as expected.

A simple agglutination system for rapid antigen detection from large sample volumes with enhanced sensitivity

Lateral flow assays (LFAs) provide a simple and quick option for diagnosis and are widely adopted for point-of-care or at-home tests. However, their sensitivity is often limited. Most LFAs only allow 50 μL samples while various sample types such as saliva could be collected in much larger volumes. Adapting LFAs to accommodate larger sample volumes can improve assay sensitivity by increasing the number of target analytes available for detection. Here, a simple agglutination system comprising biotinylated antibody (Ab) and streptavidin (SA) is presented. The Ab and SA agglutinate into large aggregates due to multiple biotins per Ab and multiple biotin binding sites per SA. Dynamic light scattering (DLS) measurements showed that the agglutinated aggregate could reach a diameter of over 0.5 μm and over 1.5 μm using poly-SA. Through both experiments and Monte Carlo modeling, we found that high valency and equivalent concentrations of the two aggregating components were critical for successful agglutination. The simple agglutination system enables antigen capture from large sample volumes with biotinylated Ab and a swift transition into aggregates that can be collected via filtration. Combining the agglutination system with conventional immunoassays, an agglutination assay is proposed that enables antigen detection from large sample volumes using an in-house 3D-printed device. As a proof-of-concept, we developed an agglutination assay targeting SARS-CoV-2 nucleocapsid antigen for COVID-19 diagnosis from saliva. The assay showed a 10-fold sensitivity enhancement when increasing sample volume from 50 μL to 2 mL, with a final limit of detection (LoD) of 10 pg mL−1 (∼250 fM). The assay was further validated in negative saliva spiked with gamma-irradiated SARS-CoV-2 and showed an LoD of 250 genome copies per μL. The proposed agglutination assay can be easily developed from existing LFAs to facilitate the processing of large sample volumes for improved sensitivity.

A Comprehensive Phylogenetic Analysis of SARS-CoV-2: Utilizing a Novel and Convenient In-House RT-PCR Method for Characterization without Virus Culture and BSL-3 Facilities.

We developed a convenient method for amplifying the complete SARS-CoV-2 sequence using in-house RT-PCR without virus culture. Forty-one stored throat swabs and blood specimens were collected from eight SARS-CoV-2 infections at multiple time points. Total RNA was extracted using the QIAamp viral RNA mini kit and pooled for higher RNA levels. Only those positive specimens by commercial real-time RT-PCR (RT-qPCR) were selected and amplified by in-house RT-PCR for complete sequences, followed by sequencing. Phylogenetic trees and exploratory analyses were performed using MEGA 11 and Simplot 3.5.1 software. Swab samples had significantly higher total RNA concentrations than plasma (p < 0.01). Positive results were found mainly in swabs, but one was found in plasma. Successful gene amplification depended on Ct values (Ct < 38). A non-synonymous substitution was found in ORF1ab/Nsp3 (at NC045512.2 position 6312, C to A) and most spike protein mutations occurred in the S1 subunit (residues 14-685). The proposed method is time-saving and reliable for rapid genomic analysis. Increasing sample volume and pooling them for RNA extraction increases RNA concentration without culture. Combining nucleotide sequences from specific variable regions of the genome is more efficient than conventional methods.

Comparison of mouth rinsing performance between adults and children using a contactless vital sensing camera.

Evaluating mouth rinsing skills is useful for assessing oral function, however current evaluation methods are subjective. This study compared mouth rinsing between adults and children using a contactless camera to capture lip motion. The subjects comprised 16 adults and 13 children with no oral dysfunction. A compact vital sensing camera adapted from a Microsoft Xbox One Kinect Sensor® (Kinect) was placed 100 cm from the floor and 120 cm from the subject; 5, 10 and 15 ml of water were used as samples. Participants were instructed to hold the sample in the oral cavity, close the lips and move the sample alternatively left and right for 15 s. Maximum/minimum displacement from the reference plane and rinsing cycle for each sample were analysed by one-way analysis of variance. In adults, there was no significant difference in the maximum/minimum displacement between the left and right sides of the angulus oris due to differences in sample amount. In children, the right maximum significantly differed between the 5- and 15-ml and 10- and 15-ml samples, while the left maximum significantly differed between the 5- and 10-ml and 5- and 15-ml samples. The right minimum significantly differed between the 5- and 10-ml samples, as did the duration of mouth rinsing between the 5- and 15-ml samples. In children, lip movement and mouth rinsing duration tended to decrease with increasing sample volume. Evaluating lip movement using a contactless vital sensing camera is useful for assessing children's development of oral function.

Improving the sensitivity of MAS spheres using a 9.5 mm spherical shell with 219 μL sample volume spinning in a spherical solenoid coil

Spherical rotors in magic angle spinning (MAS) nuclear magnetic resonance (NMR) experiments have potential advantages relative to cylindrical rotors in terms of ease of fabrication, low risk of rotor crash, easy sample exchange, and better microwave access. However, one major disadvantage so far of spherical rotors is poor NMR filling factor due to the small sample volume and large cylindrical radiofrequency (RF) coil. Here we present a novel NMR coil geometry in the form of a spherical coil. The spherical coil best fits the spherical sample to maximize sensitivity, while also providing excellent RF homogeneity. We further improve NMR sensitivity by employing a spherical shell as the rotor, thereby maximizing sample volume (219 μL in this case of 9.5 mm outer diameter spheres). The spinning gas is supplied by a 3D-printed ring stator external to the coil, thereby introducing a simplified form of MAS stators. In this apparatus, the RF field generated along the coil axis is perpendicular to the external magnetic field, regardless of rotor orientation. We observe a linear increase in sensitivity with increasing sample volume. We also simulate the RF performance of spherical and cylindrical solenoid coils with constant or variable pitch for spherical and cylindrical rotors, respectively. The simulation results show that spherical solenoid coils generate comparable B1 field intensities but have better homogeneity than cylindrical solenoid coils do.

Effect of Pore‐Scale Heterogeneity on Scale‐Dependent Permeability: Pore‐Network Simulation and Finite‐Size Scaling Analysis

AbstractA long‐standing issue in subsurface hydrology and many other related disciplines has been the scaling problem. Although the effect of length scale has been known for years, inconsistent results have been reported in the literature. Experimental data mostly indicate that the permeability k should increase with increasing sample volume, whereas simulations and some theoretical predictions appear to imply the opposite. In this paper, we use the concept of finite‐size scaling to propose a vigorous theoretical framework for addressing the effect of length scale on the permeability. We simulate fluid flow in 12 synthetic and 4 Fontainebleau pore networks to investigate the effect of small‐scale heterogeneities, such as pore‐throat size distribution and pore connectivity. Simulations were carried out for 10 pore coordination numbers, namely, Z = 1.5, 1.65, 1.75, 2, 3, 3.25, 3.5, 4, 5, and 6. For the synthetic pore networks we find a transition in the scale dependence of the permeability, with our results indicating that the permeability increases with the scale for larger pore coordination numbers, whereas the opposite is true for smaller Z. In Fontainebleau pore networks, on the other hand, the trends are decreasing permeabilities regardless of Z. Although the plot of the permeability versus the network size for each pore network appears scattered, through finite‐size scaling analysis the data collapse onto a single quasi‐universal curve. Our results demonstrate that finite‐size scaling analysis is a powerful approach for addressing the effect of length scale on the permeability.

Influence of Filter Pore Size on Composition and Relative Abundance of Bacterial Communities and Select Host-Specific MST Markers in Coastal Waters of Southern Lake Michigan.

Water clarity is often the primary guiding factor in determining whether a prefiltration step is needed to increase volumes processed for a range of microbial endpoints. In this study, we evaluate the effect of filter pore size on the bacterial communities detected by 16S rRNA gene sequencing and incidence of two host-specific microbial source tracking (MST) markers in a range of coastal waters from southern Lake Michigan, using two independent data sets collected in 2015 (bacterial communities) and 2016–2017 (MST markers). Water samples were collected from river, shoreline, and offshore areas. For bacterial communities, each sample was filtered through a 5.0-μm filter, followed by filtration through a 0.22-μm filter, resulting in 70 and 143 filter pairs for bacterial communities and MST markers, respectively. Following DNA extraction, the bacterial communities were compared using 16S rRNA gene amplicons of the V3–V4 region sequenced on a MiSeq Illumina platform. Presence of human (Bacteroides HF183) and gull (Gull2, Catellicoccus marimammalium) host-specific MST markers were detected by qPCR. Actinobacteriota, Bacteroidota, and Proteobacteria, collectively represented 96.9% and 93.9% of the relative proportion of all phyla in the 0.22- and 5.0-μm pore size filters, respectively. There were more families detected in the 5.0-μm pore size filter (368) than the 0.22-μm (228). There were significant differences in the number of taxa between the two filter sizes at all levels of taxonomic classification according to linear discriminant analysis (LDA) effect size (LEfSe) with as many as 986 taxa from both filter sizes at LDA effect sizes greater than 2.0. Overall, the Gull2 marker was found in higher abundance on the 5.0-μm filter than 0.22 μm with the reverse pattern for the HF183 marker. This discrepancy could lead to problems with identifying microbial sources of contamination. Collectively, these results highlight the importance of analyzing pre- and final filters for a wide range of microbial endpoints, including host-specific MST markers routinely used in water quality monitoring programs. Analysis of both filters may increase costs but provides more complete genomic data via increased sample volume for characterizing microbial communities in coastal waters.

Wicking microfluidic approach to separate blood plasma from whole blood to facilitate downstream assays.

Separation of blood plasma or serum from blood is essential for accurate analysis. Conventional blood separation requires instrumentation, reagents, and large sample volumes, limiting this process to laboratory environments with trained personnel. Full implementation of effective blood separation and analysis on microliter sample volumes for point of care (POC) diagnostics has proven extremely challenging resulting in a growing market demand, with common challenges such as expensive device fabrication processes or devices being comprised of materials which are not easily disposable. We developed a membrane-based wicking microfluidic device which is made using a simple fabrication process. This device uses a unique 3D flow channel geometry, fabricated in a polycaprolactone-filled glass microfiber membrane, to efficiently separate microliter sample volumes of blood. Colorimetric assay chemistries were integrated to demonstrate utility of these devices in POC diagnostics. The devices are capable of separating both fresh and anticoagulant-treated blood at microscale sample volumes (<15.0μL). Modifications to the base device are also reported herein which increased sample volume capacity and separation efficiency. Integrated colorimetric assay enabled semi-quantitative detection of conjugated bilirubin in real blood samples (1.0-1.5mg/dL). These blood separation devices, fabricated on polycaprolactone-filled glass microfiber, enabled effective blood plasma (anticoagulant-treated blood) and serum (fresh blood) separation with microscale sample volumes. Sample volume capacity and separation efficiency are customizable for specific applications and devices can be integrated with downstream assay chemistries to develop complete POC devices that offer blood separation and diagnostics at the same time on a single membrane.

THE RESEARCH ON RELATIONS BETWEEN UNIVERSITY LECTURERS’ REFLECTION AND THEIR PROFESSIONAL SELF-CREATION

The article formulates the concept of university lecturers’ professional self-creation based on the theoretical analysis of scientific works and determinate the importance of reflection for their professional self-creation. The results of the performed empirical study on university lecturers’ reflection and its importance for their professional self-creation are presented. The following techniques were used: A. Karpov’s method examining reflexivity, D. Leontyev’s test “The differential type of reflection”, the method examining self-development and professional pedagogical work (L. Berezhnova, modification and adaptation by L. Podkorytova), the method examining an actualized need for self-development, the short scale for self-actualization. The examined university lecturers had average reflexivity (according to A. Karpov), general reflection, quasi-reflection and introspection (according to D. Leontiev) and high systemic reflection (according to D. Leontiev). The obtained results partially confirmed our hypothesis that lecturer’s reflection is average: it was really average in the terms of reflexivity, introspection and quasi-reflection, but high in the terms of systemic reflection. The lecturer’s had an average or higher desire for self-development and quite successfully implemented it, the respondents showed mostly high self-actualization. As for the identified problems in the studied sample, lecturers underestimated their personal qualities. The correlation analysis was applied for the studied indicators. A direct (positive) correlation was determined between university lecturers’ reflection and professional self-creation. Reflection, in general, contributed to lecturers’ professional creation, especially to the fulfilled need for self-development and self-creation. Systemic reflection was especially important for self-creation and self-development. We have substantiated and presented an art therapy program to develop university lecturers’ reflection. The program consisted of 10 lessons and contained art therapeutic exercises proposed by V. Kokorenko, L. Lebedeva, L. Podkorytova. The art therapy developing university lecturers’ reflection was chosen due to its following features: deep reflexive nature, resourcefulness, richness of metaphors. Further research are seen in increased sample volume and number of used psychological examining tools to clarify links between university lecturer’s reflection and their self-esteem, self-attitude, value system; to study analogues links characteristic for other professional groups; to approbate the developed art therapy training and to conduct a forming experiment to clarify a role of reflection in university lecturer’s professional self-creation.

How pore structure non‐stationarity compromises flow properties representativity (REV) for soil samples: Pore‐scale modelling and stationarity analysis

AbstractClassic soil physics relies heavily on the concept of representative elementary volume (REV), which is necessary to perform upscaling from the studied soil samples and parameterize continuum scale hydrological models (e.g., based on Richards or Darcy equations). In this paper, we explore the boundaries of the classic REV concept and conventional representativity studies that claim REV for any given physical property, and that its values converge to a steady value with increasing sample volume. We chose two undisturbed soil samples of standard size from Ah and B horizons, subcropped two subvolumes within each of them and performed pore‐scale flow simulations using binarized X‐ray microtomography scans as input data. The volume of the simulation domains was 9003 voxels, with a physical volume within two orders of magnitude of the whole soil core. Based on the 3D pore geometry images and the resulting flow velocity and pressure fields, we performed REV analysis for the saturated hydraulic conductivity and porosity. Although in general subvolumes showed classical REV behaviour (convergence of porosity and saturated hydraulic conductance (Ksat)to plateau‐like behaviour), their flow properties converged to different REV values. We also evaluated the stationarity of pore structures by computing the directional correlation functions to explain the observed non‐unique behaviour. We concluded that neither of the studied samples can be considered to be representative due to their structural non‐stationarity. We extensively discussed the implications of these results for the upscaling and parameterization of continuum‐scale flow models. We argued that the plateau in Ksat (or any other physical property) is a necessary, but insufficient, condition for the REV, which requires (at least) pore structure stationarity as an additional criterion. REV as a concept is much broader than previously anticipated and the possibility of establishing REVs in structured soils will require an analysis of tensorial flow properties with correct boundary conditions, multiscale soil structure imaging with stationarity analysis, and pore‐scale simulations on fused multiscale images.Highlights Ksat analysis within subvolumes showed classical REV behaviour but resulted in non‐unique REVs for the soil samples studied Based on the stationarity analysis we argued that the conventional soil core samples studied were not REVs Plateau‐like behaviour in physical properties is a necessary but insufficient condition for REV Soil structure information is necessary to properly establish REV or upscale flow properties

Determination of the Total Concentration of Halogen- and Sulfur-Organic Compounds in Vegetable Oils of Different Degrees of Purity—a New Approach to Assessing Their Safety

A methodology is proposed for the highly selective, sensitive, and reliable determination of the total concentration of halogen and sulfur organic compounds in vegetable oils in the presence of inorganic salts, based on the direct high-temperature conversion of an oil sample in a stream of pure oxygen, absorption of inorganic salts in a reactor, absorption of the products of analyte conversion with deionized water to form F–, Cl–, Br–, and S $${\text{O}}_{4}^{{2 - }}$$ anions, and their determination in the absorbate by ion chromatography. An increase in the reliability of the determination of F–, Cl–, and Br– anions is provided by combining the registration of retention times in the direct determination of anions with an analysis of the flow of the same absorbate after the selective removal of F–, Cl–, and Br– anions (together) using corresponding adsorption columns packed with cation exchangers R–Al3+ (for F–) and R–Ag+ (for Cl– and Br–) (possibility of distortion of the determination result of these anions due to potentially coeluted components is excluded). Using the proposed methodology, the total concentration of halogen and sulfur organic compounds is determined in samples of vegetable oils of varying degrees of purity. It ranged from 2 × 10–6 to 6.0 × 10–2% (in terms of element), depending on the sample and element, at a sample volume of 1 μL. A possibility of increasing sample volume by up to 15 times and lowering the limits of detection to 10–7% (in terms of element) is shown.

Влияние скин-эффекта и активных потерь на интенсивность линий ЭПР в полупроводящих веществах

The influence of the skin effect and active losses in samples of a semiconducting composite with a wide range of conductivity values on the intensity of the EPR absorption line was studied. An approach is proposed that makes it possible to obtain a satisfactory agreement between the calculated and experimental results. It is shown that, depending on the conductivity of the test substance, absorption line intensity, corresponding to a unit volume, can decrease significantly with increasing sample volume.

Descriptors for High Throughput in Structural Materials Development.

The development of novel structural materials with increasing mechanical requirements is a very resource-intense process if conventional methods are used. While there are high-throughput methods for the development of functional materials, this is not the case for structural materials. Their mechanical properties are determined by their microstructure, so that increased sample volumes are needed. Furthermore, new short-time characterization techniques are required for individual samples which do not necessarily measure the desired material properties, but descriptors which can later be mapped on material properties. While universal micro-hardness testing is being commonly used, it is limited in its capability to measure sample volumes which contain a characteristic microstructure. We propose to use alternative and fast deformation techniques for spherical micro-samples in combination with classical characterization techniques such as XRD, DSC or micro magnetic methods, which deliver descriptors for the microstructural state.

Field Test and Validation of the Multiplier Measles, Mumps, Rubella, and Varicella-Zoster Multiplexed Assay System in the Democratic Republic of the Congo by Using Dried Blood Spots.

Here we describe baseline validation studies and field performance of a research-use-only chemiluminescent multiplex serology panel for measles, mumps, rubella, and varicella-zoster virus used with dried blood spots in support of the 2013-2014 Democratic Republic of the Congo Demographic and Health Survey. Characterization of the panel using U.S. FDA-cleared commercial kits shows good concordance for measles, mumps, rubella, and varicella-zoster with average sensitivity across assays of 94.9% and an average specificity of 91.4%. As expected, performance versus available standards validated for plaque-reduction assays does not provide a 1:1 correspondence with international units and yet demonstrates excellent linearity (average Hill's slope = 1.02) and ∼4 logs of dynamic range. In addition, for the four assays, the multiplexed format allowed for inclusion of three positive and two negative controls for each sample. A prototype Dynex Multiplier chemiluminescent automated immunoassay instrument with a charge-coupled device camera provided a rugged and robust processing and data acquisition platform. Performance of a multiplex instrument for serological testing in a substantially resource-limited environment shows excellent reproducibility, minimal cross-reactivity, and a clear discrimination between specific assays and should be considered a viable option for future serosurveys.IMPORTANCE The critical evaluation of immunization programs is key to identifying areas of suboptimal vaccination coverage, monitoring activities, and aiding development of public health policy. For evaluation of vaccine effectiveness, direct antibody binding assay methods, including enzyme immunoassay, enzyme-linked fluorescence assays, and indirect immunofluorescence assay, are most commonly used for detection of IgG antibodies. However, despite their well-demonstrated, reliable performance, they can be labor-intensive and time-consuming and require separate assays for each individual marker. This necessitates increased sample volumes, processing time, and personnel, which may limit assessment to a few key targets in resource-limited settings, that is, low- and middle-income locations where funding for public health or general infrastructure that directly impacts public health is restricted, limiting access to equipment, infrastructure, and trained personnel. One solution is a multiplexed immunoassay, which allows for the detection of multiple analytes in a single reaction for increased efficiency and rapid surveillance of infectious diseases in limited-resource settings. Thus, the scope of the project precluded a full validation, and here we present abbreviated validation studies demonstrating adequate sensitivity, specificity, and reproducibility.

Effect of Microstructure Deficiency on Quasi-static and Dynamic Compressive Strength of Crystalline Rocks

Grain size and microdeficits control static and dynamic behavior of crystalline rocks. Therefore, characterization and evaluation of the impact of such intrinsic parameters on mechanical behavior of rocks are necessary. Two marble stones of Baghat and Maroon in Iran, which consist of a unique mineral composition but different microstructural features, were selected as test samples. Microstructures of rocks were characterized using different techniques such as scanning electronic microscopic, fluorescent replacement and polarization microscopic techniques. A number of both rock types with different sizes were prepared and subjected to quasi-static and dynamic loading by a split Hopkinson pressure bar under different strain rates conditions, and mechanical properties of both marbles were measured. Microscopic studies about microstructure deficits show that fractal dimension in Maroon marble is higher than in Baghat marble. The results also show that the dynamic strength in both marbles is higher than their static strength. Strain rate controls mechanical properties in both rock types; however, in Baghat marble with a relatively lower microstructure intensity, this phenomenon is more significant. With increasing sample volume, dynamic strength of rocks is decreased. Morphology study of fracture surface in microscale indicated that in dynamic loading the intensity of created microcracks particularly intercrystalline microcracks is increased compared to the quasi-static loading condition.

Deterministic lateral displacement (DLD) in the high Reynolds number regime: high-throughput and dynamic separation characteristics

Recent progress in the development of biosensors has created a demand for high-throughput sample preparation techniques that can be easily integrated into microfluidic or lab-on-a-chip platforms. One mechanism that may satisfy this demand is deterministic lateral displacement (DLD), which uses hydrodynamic forces to separate particles based on size. Numerous medically relevant cellular organisms, such as circulating tumor cells (10–15 µm) and red blood cells (6–8 µm), can be manipulated using microscale DLD devices. In general, these often-viscous samples require some form of dilution or other treatment prior to microfluidic transport, further increasing the need for high-throughput operation to compensate for the increased sample volume. However, high-throughput DLD devices will require a high flow rate, leading to an increase in Reynolds numbers (Re) much higher than those covered by existing studies for microscale (≤ 100 µm) DLD devices. This study characterizes the separation performance for microscale DLD devices in the high-Re regime (10 < Re < 60) through numerical simulation and experimental validation. As Re increases, streamlines evolve and microvortices emerge in the wake of the pillars, resulting in a particle trajectory shift within the DLD array. This differs from previous DLD works, in that traditional models only account for streamlines that are characteristic of low-Re flow, with no consideration for the transformation of these streamlines with increasing Re. We have established a trend through numerical modeling, which agrees with our experimental findings, to serve as a guideline for microscale DLD performance in the high-Re regime. Finally, this new phenomenon could be exploited to design passive DLD devices with a dynamic separation range, controlled simply by adjusting the device flow rate.

Investigation of Water-Washing Process Parameters for Removal of Alkali Metals and Chlorides from Electric Arc Furnace Dust (EAFD)

The present study investigated the effect of a water-washing process, which is part of the acid hydrometallurgical process for recovery of high purity of zinc, on the removal of alkali metals and chlorides (Na, K, Ca, Cl) from Electric arc furnace dust (EAFD). Two EAFD samples with different properties were characterized by particle size, XRD and element analysis, and their washing efficiencies (%) on alkali metals and chlorides were compared according to pH, washing time, liquid to solid (L/S) ratio and number of washings. The results show that the alkali metals and chlorides could be effectively removed by the washing (at L/S ration of 3 for more than 30 min., pH 10~11) while minimizing loss of zinc (<0.1%), in which the washing efficiency was Na-78%, K-76%, Cl >99%, respectively. Na and K could be removed up to 97% and 89% respectively by 3 times of repeated washings. With increased sample volume (10 times) of the mixed (1:1, w/w) sample with two types of EAFD, it was confirmed that the pH(10~11) can be used as the main process control parameter for the washing of the alkali metals regardless of EAFD properties. Key words: EAFD, pH, Water-Washing, Alkali Metals, Chlorides

Abstract 204: In vitro metabolomics of mesothelioma: Challenges and outcomes

Abstract Introduction Early detection of malignant pleural mesothelioma (MPM) is likely to improve outcome in affected patients. From our previous studies (MesoBreath 1 &amp; 2) we developed a screening tool in which volatile organic compounds (VOCs) in breath allowed discrimination of MPM patients from at risk controls. However it is not yet clear which VOCs arise from the neoplastic cells themselves or from the host response. Identifying the cancer cell-specific compounds should increase the specificity of our breathomic signature model. Therefore, we set up an in vitro experimental setup model for VOC analysis from the headspace of mesothelioma cell lines. Methods Standard polystyrene culture flasks (NunclonTM Delta Surface, Thermo Scientific) were mounted with an adapted cap accommodating teflon inlet and outlet tubes. The inlet tube provides environmental air while an external pump (Gilian GilAir Plus, Sensidyne) draws headspace air from the outlet tube over an adsorption column (Tenax GR, Markes International, UK). The adsorption columns were further processed on a GC-MS platform (GC: Focus GC, Thermo Finnigan, Milan, Italy; DSQII Single Quadrupole MS, Thermo Finnigan, Austin, TX, USA). VOC profiles were processed using supervised clustering algorithms and principal component analysis. Results Using this setup, we have investigated the impact of flow and total sampled volume on the concentration and range of VOCs detected. For a constant flow, VOCs were detected in higher concentrations with increasing sample volume. For a constant volume, a lower sampling flow yielded a higher concentration of detected VOCs. Most of the VOCs obtained were alkanes and ketones. We will show data illustrating the differential VOC profiles of container plastic, cell culture medium and growing mesothelioma cancer cells, as well as the differential VOC output of epithelioid vs sarcomatoid mesothelioma cell lines. Conclusions We have succesfully developed an in vitro experimental setup allowing collection and analysis of VOCs emanating from mesothelioma cancer cell line cultures. This platform will allow us to investigate how VOC profiles are impacted in different experimental conditions (e.g. hypoxia, nutrient deprivation, cytostatics, co-culture with leukocytes). The data collected will help us to pinpoint the cancer cell-derived VOCs from patient exhaled breath, and increase the robustness of our mesothelioma breathomic signature. Note: This abstract was not presented at the meeting. Citation Format: Sabrina Lagniau, Kevin Lamote, Lore Vandermeersch, Herman Van Langenhove, Jan P. van Meerbeeck, Karim Y. Vermaelen. In vitro metabolomics of mesothelioma: Challenges and outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 204. doi:10.1158/1538-7445.AM2017-204

Evaluation of HBsAg and anti-HBc assays in saliva and dried blood spot samples according HIV status

Influence of HIV status in HBV markers detection in saliva and dried blood spots (DBS) was not well established. This study aims to evaluate the performance of optimized commercial immunoassay for identifying HBsAg and anti-HBc in saliva and DBS according HIV status. A sum of 535 individuals grouped as HIV+, HBV+, HIV/HBV+ and HIV/HBV- were recruited where 347 and 188 were included for HBsAg and anti-HBc evaluation, respectively. Serum, DBS collected in Whatman 903 paper and saliva obtained using salivette device were analyzed using EIA. Increased sample volume and ROC curve analysis for cut off determination were used for DBS and saliva testing. HBsAg detection in saliva and DBS exhibited sensitivities of 80.9% and 85.6% and specificities of 86.8% and 96.3%. Sensitivity of anti-HBc in saliva and DBS were 82.4% and 76.9% and specificities in saliva and DBS were 96.9% and 91.7%. Low sensitivities were observed for HBsAg (62%) and anti-HBc (47%) detection in saliva of HIV/HBV+ individuals. OD values were also lower for HBsAg detection in DBS and saliva of HIV/HBV+ individuals compared to their serum samples. Statistical significance was found for sensitivities in HBsAg detection between saliva and DBS demonstrating high sensitivity for DBS specimens. In conclusion, HIV status or antiretroviral treatment appears to interfere in the performance of HBsAg and anti-HBc detection in DBS and saliva samples using the adapted commercial EIA.