Laboratory Specimens Research Articles

A retrospective safety study on screening of the samples in the clinical biobank of Beijing Hospital

To investigate whether the laboratory specimens preserved in Beijing Hospital Biobank during a specific period had been contaminated by SARS-Cov-2 through a cross-sectional study, and to establish a retrospective biobank safety screening system. Laboratory specimens were collected from the Department of Respiratory and Critical Care Medicine and the Fever Clinic of Beijing Hospital from November 1, 2019 to January 22, 2020, nucleic acid and serological antibody testing were performed for SARS-CoV-2 in these specimens (including 79 serum, 20 urine, 42 feces and 21 bronchoalveolar lavage fluid specimens). The safety of the stored samples during this period was defined by negative and positive results. Both the nucleic acid test and serological antibody test showed negative for SARS-CoV-2, indicating that these specimens were safely stored in the biobank. High-risk specimens collected in our hospital during the early stage of the COVID-19 outbreak are free of SARS-CoV-2, and a safety screening strategy for the clinical biobank is established to ensure the biosafety of these samples.

EMERGENCE OF MULTIDRUG RESISTANT NFGNB AS AN IMPORTANT CAUSE OF INFECTIONS

Background: The non fermenter gram negative bacilli (NFGNB) are primarily opportunistic pathogens and have emerged as an important cause of health care associated infections. The Methods: non fermenter organisms were isolated from various clinical specimens in a microbiology laboratory of a tertiary care hospital and were identied by the conventional bacteriological identication methods. Susceptibility testing was performed by methods as recommended by Clinical Laboratory Standard Institute (CLSI). Results: A total of 10,456 clinical specimens were processed, of which 442 (4.23%) non fermenter spp. were isolated. Most common infection caused by non fermenters was abscess. Maximum numbers of isolate (52.94%) were of Pseudomonas aeruginosa, followed by Acinetobacter baumannii (42.76%). Other species isolated were Acinetobacter calcoaceticus (1.81%), Pseudomonas putida (1.13%), Acinetobacter lwofi (0.68%), Pseudomonas stutzeri (0.45%), Stenotrophomonas maltophilia (0.23%). The isolation rate of non fermenters from ICU was much higher compared to general ward. High antibiotic resistance was noted for commonly used antibiotics like cephalosporins, quinolones, aminoglycosides. A total 58.60% of multi drug resistant (MDR) non fermenter isolates were obtained. The isolation rate of MDR isolates of non fermenters was more from ICU compared to general ward. Nosocomial infections res Interpretation and Conclusion: istant to most antimicrobials caused by non fermenter organisms have emerged, especially in ICU. Early identication and continued surveillance will help to prevent their spread in hospital environment.

Mechanical properties and fracturing of rock-backfill composite specimens under triaxial compression

In the mining industry, backfill is used to stabilize mined-out underground excavations, and backfill made from mine tailings has the added advantage of being sustainable and eliminating the hazards of storing tailings on the surface. Triaxial compressive tests were conducted on laboratory specimens containing both rock and backfill, in order to better understand the effects of rock/backfill volume fraction and confining pressure on the strength and fracturing in rock-backfill systems. The importance of the interface between rock and backfill was also studied by conducting before and after CT scanning. The results are very interesting and show that shear and tensile fracturing in the rock as loading progresses occurs concurrently with slip and failure of the rock-backfill interface, resulting in unique stress-strain behavior, crack dilatancy, and failure types. The backfill shows very little fracturing but has a major effect on the effective strength and elastic properties of the combined specimens. The results provide important details on the failure process of rock-backfill systems and provide guidelines for the safe design of underground excavations in rock.

Using flower strips to promote green lacewings to control cabbage insect pests

Habitat management improves biological control by increasing the abundance and fitness of natural enemies through the provision of floral resources along field edges or between crops. Among the natural enemies reliant on flower resources, green lacewings often stand out due to their abundance, predation capacity and polyphagy. We evaluated the impact of tailored flower strips on the enhancement of natural enemies, especially green lacewings, in three organic cabbage (Brassica oleracea) farms in Southern Sweden. Insects were sampled from the flower strips, and cabbage pests and predators were visually recorded in the crop. In a laboratory assay, the pollen feeding preferences of Chrysoperla carnea (Stephens, 1836) were evaluated in a dual-choice test. The pollen consumed by the Chrysopidae was extracted from laboratory and field specimens, then quantified and identified. Flower strips were found to attract predators and parasitoids, whose abundance increased as flowers bloomed. Cabbage plants next to the flower strips showed lower pest infestation as compared to cabbage plant control, although no significant differences were observed in the number of predators. Chrysopidae used flower strips as feeding, reproduction and shelter sites and mainly consumed pollen from Phacelia tanacetifolia Benth. Under laboratory conditions, C. carnea showed a preference for P. tanacetifolia and Coriandrum sativum L. pollen over Borago officinalis L. and Fagopyrum esculentum Moench. We show that tailored flower strips could be an efficient tool for enhancing beneficial arthropods and should be considered in integrated pest management for cabbage crops.

Performance grade of asphalt mixtures based on mixture performance test thresholds

At present, the way of fingerprinting a multi-binder, heterogeneous asphalt mixture systems involves the testing of extracted and recovered binder from lab specimens or field cores. However, concerns have been raised over the recovery of a truly representative binder sample from mixtures with modified binder system (additives, recycled binder, etc). On the other hand, mixture performance tests have been shown to: a) distinguish between different constituents of an asphalt mixture, and b) correlate well to the field performance. This study attempts to establish necessary groundwork to allow the development of a mixture-based, usable temperature grading system as an alternative to the existing grading system for recovered binders. A novel Mixture Performance Grading system is proposed that utilizes two mixture tests, namely, the Hamburg wheel track test (HWTT) and Disk-shaped compact tension (DC(T)) test, to compute a mixture-based performance grade. Both tests have shown excellent correlation with field performance data, and permit high and low temperature grading along with the computation of a mixture-based Usable Temperature Interval (UTI). The grading system involves conducting the tests at multiple temperatures and then using appropriate thresholds to find a failure temperature, analogous to current specification to determine failure temperatures of recovered binder. Eight mixtures were tested in this study including mixtures placed on Missouri roads (referred to as Level 1 mixes) and mixtures with various modifications (referred to as Level 2 mixes). The mixture grading approach was found to appropriately credit mixtures composed of high-quality aggregate structures, binders, additives, interactions between mixture ingredients, and those with good mixture volumetric designs. Obviously, the ability to evaluate the efficacy of mixture-based ingredients and mixture design variables is a key evolutionary step over traditional (and cumbersome) binder grading for modern, heterogeneous recycled asphalt mixtures.

Optimization of Copper Stain Removal from Marble through the Formation of Cu(II) Complexes in Agar Gels.

Copper complexes with different ligands (ethylenediaminetetraacetic acid, EDTA, ammonium citrate tribasic, TAC, and alanine, ALA) were studied in aqueous solutions and hydrogels with the aim of setting the optimal conditions for copper stain removal from marble by agar gels, with damage minimization. The stoichiometry and stability of copper complexes were monitored by ultraviolet-visible (UV-Vis) spectroscopy and the symmetry of Cu(II) centers in the different gel formulations was studied by electron paramagnetic resonance (EPR) spectroscopy. Cleaning effectiveness in optimized conditions was verified on marble laboratory specimens through color variations and by determining copper on gels by inductively coupled plasma-mass spectrometry (ICP-MS). Two copper complexes with TAC were identified, one having the known stoichiometry 1:1, and the other 1:2, Cu(TAC)2, never observed before. The stability of all the complexes at different pH was observed to increase with pH. At pH 10.0, the gel’s effectiveness in removing copper salts from marble was the highest in the presence of ALA, followed by EDTA, TAC, and pure agar gel. Limited damage to the marble surface was observed when gels with added EDTA and TAC were employed, whereas agar gel with ALA was determined to be the most efficient and safe cleaning material.

Cyclic shearing behavior and dynamic characteristics of a fibrous peat

Cyclic shearing behavior, dynamic characteristics, and post-cyclic volume change of a peat sublayer from the Port Lands area of Toronto (Ontario, Canada) are investigated in this study. Laboratory specimens are trimmed from block samples collected from a depth of about 4.0 to 4.5 m. Constant-volume cyclic direct simple shear tests indicate an initial reduction of effective stress with number of stress cycles. However, the corresponding excess pore pressure ratios do not exceed 60%, indicating a cyclic mobility behavior in the peat specimens. Maximum shear moduli of the peat samples are also determined from shear wave velocity measurements. Post-cyclic volumetric strain, as well as the variations of secant modulus, modulus reduction, and damping ratio of the peat, are presented in terms of cyclic shear strain and compared with other studies. Empirical relationships are proposed for characterizing the shear modulus and damping ratio of Toronto peat.

Preparing for the Unknown: Simulation-based Training in a New Procedural /PACU Area to Increase Patient Safety

<h3>Background Information</h3> Opening a new procedural area and post anesthesia care unit (PACU) can present potential risk of complications. An education need was identified to establish and test workflows for 3 new procedural areas to ensure patient safety measures. Simulation-based team training was developed for all interdisciplinary team members working in the new setting. <h3>Objectives of Project</h3> The goal of this training was to test new workflows to ensure efficiency and to establish patient safety measures in a new ambulatory procedural and PACU environment. <h3>Process of Implementation</h3> All interdisciplinary team members were surveyed prior to the simulation regarding their experience with simulation training and to assess primary patient safety concerns. Nursing leadership and informatics analysts coordinated the simulation planning. A test patient was developed in the customized electronic health record (EHR) template for the procedural and PACU area. A detailed workflow was developed covering the multiple roles impacting the patient's visit. Test patients were created with three separate scenarios for the different modalities. An additional scenario was included for the activation of the institutional Medical Emergency Rapid Intervention Team (MERIT). A brief was provided prior to each simulation scenario and tasks were assigned based on roles. The scenarios followed the patient from check-in through discharge. Each simulation included several anticipated workflow challenges such as laboratory testing, specimen collection, chest X-rays and MERIT team activation. At the completion of each simulation activity, a debrief session led by PACU nursing leadership was held to discuss identified areas of improvement, patient safety concerns, workflow challenges and team collaboration. Feedback forms were provided during the simulation to record specific patient safety concerns and barriers to providing safe care. A list was compiled to address critical needs prior to the scheduled go-live date. A post-survey was provided to evaluate the effectiveness of the simulation activity. <h3>Statement of Successful Practice</h3> Post-survey results revealed that 91% of participants felt confident and prepared; 76% felt safety concerns were addressed; 18% identified patient safety concerns and all participants felt that their learning needs were met. <h3>Implications for Advancing the Practice of Perianesthesia Nursing</h3> Providing simulation training for multidisciplinary teams in a new procedural and PACU area could improve patient outcomes, establish cohesive workflows, and increase knowledge and confidence.

Application of Composite Materials in an Upgraded Engine Low-Pressure Compressor for a Regional Passenger Aircraft

Computational and experimental studies have been carried out to evaluate the robustness and durability of components produced of polymer composite materials (PCM), as a part of the modernization of the low-pressure compressor (LPC) of the engine for the regional aircraft. For a preliminary assessment of the static and dynamic strength of the parts, a series of three-dimensional finite element calculations and tests of laboratory specimens, structural elements cut from finished parts, have been performed. Testing the laboratory samples made it possible to compare the obtained mechanical properties with the properties declared by PCM suppliers and to conduct a mor e correct assessment of the safety margins of the parts. To decide whether to install parts on the engine, fatigue and erosion tests of the structural elements cut from the finished parts were carried out. The final decision on the performance of the PCM parts was made after testing them as part of the upgraded LPC on the engine. The criterion for evaluating the erosion resistance of PCM parts has been introduced, which makes it possible to assess their performance during operation.

Standardised quantification of structural efficiency of hybrid reinforcement systems for developing concrete composites

Various types of materials and technologies have been developed either for reinforcing or strengthening concrete structures. However, there is no uniform methodology to quantify and compare the mechanical characteristics of different reinforcement systems. Residual stiffness of flexural elements is the suggested measure of the reinforcement’s structural effectiveness, involving concrete into composite action. This manuscript proposes a new testing layout designed to form multiple cracks in a small laboratory specimen and a simplified analytical approach to quantifying the flexural stiffness of the standardised test samples. The achieved analytical solution to the stiffness problem requires neither iterative calculations nor the loading history description. That makes it acceptable for quantifying and comparing the residual stiffness of elements with various combinations of reinforcement materials. The proposed analysis procedure also enables determining the mechanical performance decay under repeated and long-term loading conditions without a loss of the calculation adequacy. Flexural tests illustrate the application of the proposed technique—the 38 specimens were mechanically loaded until failure. Several composite reinforcement schemes, including steel and glass fibre reinforced polymer (GFRP) bars, externally bonded carbon fibre (CF) sheets, and near-surface mounted (NSM) carbon fibre reinforced polymer (CFRP) strips in various combinations, are considered. The analysis reveals an exceptional efficiency of hybrid reinforcement systems, combining steel and CFRP components.

Effect of the Geometrical Constraints to the Wenner Four-Point Electrical Resistivity Test of Reinforced Concrete Slabs.

The main objectives of this study are to evaluate the effect of geometrical constraints of plain concrete and reinforced concrete slabs on the Wenner four-point concrete electrical resistivity (ER) test through numerical and experimental investigation and to propose measurement recommendations for laboratory and field specimens. First, a series of numerical simulations was performed using a 3D finite element model to investigate the effects of geometrical constraints (the dimension of concrete slabs, the electrode spacing and configuration, and the distance of the electrode to the edges of concrete slabs) on ER measurements of concrete. Next, a reinforced concrete slab specimen (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)) was used for experimental investigation and validation of the numerical simulation results. Based on the analytical and experimental results, it is concluded that measured ER values of regularly shaped concrete elements are strongly dependent on the distance-to-spacing ratio of ER probes (i.e., distance of the electrode in ER probes to the edges and/or the bottom of the concrete slabs normalized by the electrode spacing). For the plain concrete, it is inferred that the thickness of the concrete member should be at least three times the electrode spacing. In addition, the distance should be more than twice the electrode spacing to make the edge effect almost negligible. It is observed that the findings from the plain concrete are also valid for the reinforced concrete. However, for the reinforced concrete, the ER values are also affected by the presence of reinforcing steel and saturation of concrete, which could cause disruptions in ER measurements.

Mesoscale modeling of fracture in cement and asphalt concrete

In this paper, mesoscale modeling is performed to simulate and understand fracture behavior of two concrete composites: cement and asphalt concrete using disk-shaped compact tension (DCT) tests. Mesoscale models are used as alternative to macroscale models to obtain better realistic behavior of composite and heterogeneous materials such as cement and asphalt concrete. In mesoscale models, aggregate and matrix are represented as distinct materials and each material has its characteristic properties. Disk-shaped compact tension test is used to obtain tensile strength and fracture energy of materials. This test can be used as a better alternative to other tests such as three points bending tests because it is more convenient for both field and laboratory specimens in addition to its accurate results. Comparing the numerical results of the mesoscale models of cement and asphalt concrete specimens with experimental data shows that these models can predict the behavior of these composite materials very well as seen in the curves of load-crack mouth opening displacement (CMOD). Also, the mesoscale modeling highlights the variability of crack direction where it is dependent on the random distribution of aggregate.

Improving thе propеrtiеs of building matеrials from limеstonе-shеll roсk by imprеgnating sulfur-сontaining prеparations basеd on loсal raw matеrials

Thе artiсlе prеsеnts rеsеarсh data on thе еffесtivеnеss of imprеgnation with polysulfidе solutions of limеstonе-shеll roсk usеd as a faсing and wall matеrial, as wеll as for thе manufaсturе of road produсts. It is еstablishеd that for сalсium polysulfidе, whеn thеy arе dilutеd with watеr or mixеd with aсid solutions, primary sulfur nanopartiсlеs with an avеragе sizе of 20 nm arе formеd, whiсh arе subsеquеntly еnlargеd in two stagеs to miсron sizеs. Modifiсation of limеstonе-shеll roсk with thе imprеgnating сomposition dеvеlopеd by us – an aquеous sulfur-сontaining solution basеd on сalсium polysulfidе, сontaining alсohols and surfaсtants - сan signifiсantly rеduсе thеir watеr absorption and inсrеasе thеir durability. Proсеssing of shеll limеstonе with a solution of сalсium polysulfidе providеs еduсation on thе surfaсе of thе porеs of thе stonе сoating basеd on nano-sulfur, whiсh partially fills thе porе spaсе and having watеr rеpеllеnсy, rеduсе watеr absorption of thе samplеs 5-8 timеs, inсrеasеs thе avеragе dеnsity of 22-27%, thе strеngth of 1.2–1.3 timеs, softеning сoеffiсiеnt – in 6-19%, whiсh allows to prеdiсt thе inсrеasе of durability of building matеrials on thе basis of limеstonе up to 1.5–2 timеs or morе. Thе imprеgnation of wall, faсing and road сonstruсtion matеrials and produсts madе of limеstonе-shеll with a polysulfidе сomposition allows to improvе thеir opеrational propеrtiеs, inсrеasе thеir rеsistanсе to atmosphеriс influеnсеs, and еxpand thеir sсopе of appliсation in сlimatiс сonditions.

Reliability‐based optimization of a prestressed concrete roof girder using a surrogate model and the double‐loop approach

AbstractThe paper describes the reliability‐based optimization of a TT‐shaped precast roof girder produced in Austria. An extensive experimental programme was performed using laboratory specimens to gain information on the mechanical fracture parameters of the utilized concrete. Subsequently, destructive shear tests were performed on scaled‐down and full‐scale girders under laboratory conditions. The experiments helped in the development of an accurate numerical model of the girder. The developed model was consequently used for the advanced stochastic analysis of structural response, followed by reliability‐based optimization, which was used to maximize the shear and bending capacities of the girder and minimize production cost under defined reliability constraints. The enormous computational requirements of the double‐loop optimization approach were significantly reduced by the utilization of an artificial neural network‐based surrogate model instead of the original nonlinear finite element model of the optimized structure.

Incidence of missing pathology specimens in dermatology.

Occasionally specimen containers are received in the dermatopathology laboratory without an accompanying specimen. The consequences in this scenario can range from delay in care and inconvenience to patients to increased morbidity and even mortality. Data regarding incidence and associated characteristics of missing specimens are scant. Over a 10-year period (7 January 2010 to 7 January 2020) all cases with a missing specimen in a single academic dermatopathology laboratory and a single dermatopathology practice embedded within a dermatology practice were reviewed. Out of 270,754 specimens received, 83 empty specimen containers were identified for an incidence of 0.031%. There were 14 (0.005%) cases in which patients had a separate procedure and a second container with both specimens in it accompanying the empty container. The most common missing specimen-generating procedures were shave biopsies (51%) with most common clinical diagnosis being unspecified (30%). The most common specimen location from the 97 total specimen bottles containing either zero or two specimens was head/neck (53%). Although no further procedures were performed after the specimen was lost for 48% of cases, re-biopsy occurred for 28%. Failure to insert specimens into the correct container is rare, but represents a potential significant negative event where vigilance and improvement is required.

Improved histological fixation of gelatinous marine invertebrates

BackgroundGelatinous zooplankton can be difficult to preserve morphologically due to unique physical properties of their cellular and acellular components. The relatively large volume of mesoglea leads to distortion of the delicate morphology and poor sample integrity in specimens prepared with standard aldehyde or alcohol fixation techniques. Similar challenges have made it difficult to extend standard laboratory methods such as in situ hybridization to larger juvenile ctenophores, hampering studies of late development.ResultsWe have found that a household water repellant glass treatment product commonly used in laboratories, Rain-X®, alone or in combination with standard aldehyde fixatives, greatly improves morphological preservation of such delicate samples. We present detailed methods for preservation of ctenophores of diverse sizes compatible with long-term storage or detection and localization of target molecules such as with immunohistochemistry and in situ hybridization and show that this fixation might be broadly useful for preservation of other delicate marine specimens.ConclusionThis new method will enable superior preservation of morphology in gelatinous specimens for a variety of downstream goals. Extending this method may improve the morphological fidelity and durability of museum and laboratory specimens for other delicate sample types.

Rapid Cell Transfer by Means of Nylon Mesh to Improve Cellular Diagnosis: The Role of Immunocytochemistry

Immunocytochemistry (ICC) is an important ancillary technique in clinical cytology for not only identifying and characterizing tumor cells but also gaining prognostic or therapeutic information. Although cell blocks are often prepared for immunocytochemical evaluation of body cavity fluid and fine-needle aspiration specimens, they are not suitable for hypocellular samples. Liquid-based cytology can help prepare additional smears from residual cytological specimens. However, since conventional methods are used for nongynecological specimens in most laboratories, ICC is often limited by the number of cytological smears. Cell transfer methods permit to evaluate several immunocytochemical markers in a single cytological smear. Yet, these methods have some limitations; for example, they are time-consuming (about 3–40 h) and medium membranes with their attached cells are occasionally stretched or torn when peeled off the slides. Therefore, in an attempt to solve these problems, we developed a rapid and reliable cell transfer method using a nylon mesh. Our method requires no special equipment or reagent and can significantly reduce the turnaround time, as compared to previous methods.

Unified correlation of constraints with crack arrest toughness for high-grade pipeline steel

There is much controversy surrounding using laboratory specimens to predict the fracture behavior of high-grade pipeline steel due to their different constraints. Since there is a lack of unified parameters to quantitatively characterize the constraint effects, a model for the transformation of crack arrest toughness between different specimens and pipes has not been formed. In order to solve this problem, the evolution law of the plastic zone of the crack tip with the crack tip opening degree under different in-plane and out-of-plane constraints is explored using the finite element simulation technology. On this basis, a constraint parameter η which is based on the area APEEQ surrounded by the isoline of equivalent plastic strain εp at the crack tip is proposed. The feasibility of this parameter to characterize both in-plane and out-of-plane constraints is discussed, and a quantitative correlation model between it and the crack arrest toughness, critical crack tip opening angle (CTOAC), is established. The results show that the proposed parameter can be used to characterize the overall constraints caused by different specimens with different loading forms and geometries. The normalized arrest toughness, CTOAC/CTOAref, has a linear relationship with η1/2, and the correlation line is only related to the material. The quantitative correlation model has universal applicability for different specimens and is expected to predict the transformation of crack arrest toughness between laboratory specimens and pipelines.

Automatic Identification and Geometrical Modeling of Steel Rivets of Historical Structures from Lidar Data

Riveting is a joining technique that was widely used in iron and steel structures from the mid-nineteenth to the early twentieth century. Nowadays, many of these riveted structures are still in service around the world, and in many instances, also constitute an important part of the built cultural heritage. The maintenance and conservation of this type of construction is a crucial task for which the HBIM (Historic Building Information Modeling) methodology has recently gained increased attention, postulating itself as the ideal tool for tracking control and conservation-related actions. In the process of data collection and 3D modeling of the structure, the rivets are an important part to be taken into account in the structural safety assessment and health monitoring over time. Any structure of this typology typically presents thousands of rivets, so its measurement and subsequent 3D geometrical modeling is a laborious task and a source of possible errors. Accordingly, this work presents a novel methodology that allows the automatic identification and 3D modeling of rivets in iron and steel structures from Lidar data. The proposed methodology has been tested with both laboratory specimens and a full-scale real bridge.

Analysis of the stress distribution in a laminar direct simple shear device and implications for test data interpretation

Direct simple shear (DSS) testing allows observation of load-deformation response under rotation of the major principal stress plane, which is descriptive of many actual field problems. While the simplicity of the test configuration makes its use popular in research and industry, key uncertainties still remain regarding the interpretation of the laboratory data. This study uses laboratory validated discrete element method (DEM) models to examine the stress transmission in laminar-type direct simple shear devices under drained constant effective stress conditions. The DEM models (comprised of spheres) closely replicate physical specimens of precision chrome steel ball bearings for which the properties (e.g., shape, surface friction, and stiffness) were measured directly. The DEM models were also validated using experimental tests, so that conclusions regarding the system response can be derived with confidence from the available DEM data. The testing program included both loose and dense specimens, allowing for a comparison of the influence of density on stress state which has not been examined in previous simple shear DEM studies. Differences were observed between vertical effective stresses and shear stresses derived from boundary measurements (as commonly carried out in experimental programs) and those derived from force measurements within the DEM specimens. The failure state of the material in simple shear was also examined through Mohr’s circles of stress. The evolution of stresses on both the horizontally and vertically oriented planes were considered so that established methods of direct simple shear interpretation could be critically assessed. For the loose specimens, the angle of shearing resistance can be confidently estimated considering the maximum shear stress acting on the horizontal plane, which is easily inferred from measurements of the shear force during the physical test. This was true considering both internal and boundary calculated stresses. This approach, however, is inaccurate for the dense specimens. Analysis of the particle-scale kinematics of the response illustrates that the deformation field within the central portion of the specimen is in simple shear, although the magnitude of this shearing was significantly larger than what was measured on the boundary. This study and the conclusions derived focus on smooth spherical particle specimens; the objective was to examine the stress distribution within DSS devices and the implications for test interpretation using DEM models that more closely matched the physical laboratory specimens tested than in previous studies. When considered alongside the existing studies, the findings show that there is no broad conclusion that can be applied for all materials and all conditions in simple shear and that interpretation should be carefully tied to the physical conditions simulated.