A New Specimen Geometry for Evaluation of the Mechanical Orthotropic Properties Presented in Parts Printed by FDM

Additive manufacturing (AM) by FDM (Fused Deposition Modeling) has been increasingly adopted due to the low cost of 3D printers as an option capable of producing parts with complex geometries. Since the FDM process is a layer-by-layer manufacturing method, the characterization of the behavior of parts manufactured by this technology, especially with regard to anisotropic mechanical properties, has led to many works relating printing parameters with tensile strength. However, the use of specimens with the conventional flat "dog bone" and cylindrical geometries specified in the ASTM-638 standards do not perfectly suit the special characteristics of parts produced by FDM, since these standards were created for solid and isotropic materials. A new geometry for specimens printed in FDM to study anisotropy transverse to layer deposition is suggested in this work. Problems such as slippage and crushing in the grips of the test machines due to the fragility of the bound between the beds, as well as the appearance of lateral forces that distort the results due to misalignment of the tensile load, twists and curvature of the specimens, normally observed in the Strain measurements by extensometers, are suppressed with the adoption of the new geometry presented in this work. Keywords: Fused Deposition Modeling, Additive Manufacturing, Mechanical Strength, Tensile Testing, Specimen Geometry

Empowering Equitable Data Use Partnerships and Indigenous Data Sovereignties Amid Pandemic Genomics

The COVID-19 pandemic has inequitably impacted Indigenous communities in the United States. In this emergency state that highlighted existing inadequacies in US government and tribal public health infrastructures, many tribal nations contracted with commercial entities and other organization types to conduct rapid diagnostic and antibody testing, often based on proprietary technologies specific to the novel pathogen. They also partnered with public-private enterprises on clinical trials to further the development of vaccines. Indigenous people contributed biological samples for assessment and, in many cases, broadly consented for indefinite use for future genomics research. A concern is that the need for crisis aid may have placed Indigenous communities in a position to forego critical review of data use agreements by tribal research governances. In effect, tribal nations were placed in the unenviable position of trading short-term public health assistance for long-term, unrestricted access to Indigenous genomes that may disempower future tribal sovereignties over community members' data. Diagnostic testing, specimen collection, and vaccine research is ongoing; thus, our aim is to outline pathways to trust that center current and future equitable relationship-building between tribal entities and public-private interests. These pathways can be utilized to increase Indigenous communities' trust of external partners and share understanding of expectations for and execution of data protections. We discuss how to navigate genomic-based data use agreements in the context of pathogen genomics. While we focus on US tribal nations, Indigenous genomic data sovereignties relate to global Indigenous nations regardless of colonial government recognition.

Motion Analysis of Torsional Testing Machine to Reduce Impact Load Using SOLIDWORK

Mechanical testing is a standard and essential part of any design and manufacturing process, for ensuring safe working of mechanical component and for ensuring a cost-effective design. Torsion Testing Machine is designed for conducting Torsion and Twist on various metal wires, tubes, sheet materials, torque measurement, in this torque can be applied to testing specimen by geared motor through gear box. But the main difficulty with analytical torsion testing machine is that after test is complete and specimen breaks the trolley on which the test specimen is clamped it can impacted heavily to the rubber stopper mounted on the guide ways of the machine which distort the machine assembly. In this study motion study is done, using SOLIDWORK software by introducing spring at the place of stopper and try to minimise this impact load of the trolley on the machine. Keywords: Torsion testing, Motion analysis, impact load, spring design, SOLIDWORK software

Stabilization of Earth Block Using Rice Husk Ash as Partial Replacement in Cement

The most outstanding problem militating the production of earth block in Nigeria, is the exorbitant prices of cement, rice ash replaced with cement, stabilized compressed earth block to carry load. The main objective of this study was to investigate the sustainability of earthen construction block with a partial replacement of cement using Rice Husk Ash (RHA). RHA is a bye-product material obtained from the combustion of rice husk which consists of non-crystalline silicon dioxide with high specific surface area and high pozzolanic reactivity using a set of sieves 3.35um - 63um, weigh balance, oven maintained at a temperature of 105°C and 110°C, six meta trays, a bucket, a soap, wire brushes, and a mechanical shaker. It is used as pozzolanic material in earth block. Testing specimen were determined and examine in structural composition by means of unconfined compressive strength hydraulically compressed for crushing the composition of mix with RHA content ranges from 10% to 50% to respectively. The result of the compressed earth block shows a significant resistance of shear strength of 30 to 90 kg/mm2, proving that stabilized earth block can satisfactorily carry load when structurally loaded and can resist tensile and compressive stresses.

Saliva as a testing specimen with or without pooling for SARS-CoV-2 detection by multiplex RT-PCR test

Background Sensitive and high throughput molecular detection assays are essential during the coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The vast majority of the SARS-CoV-2 molecular assays use nasopharyngeal swab (NPS) or oropharyngeal swab (OPS) specimens collected from suspected individuals. However, using NPS or OPS as specimens has apparent drawbacks, e.g. the collection procedures for NPS or OPS specimens can be uncomfortable to some people and may cause sneezing and coughing which in turn generate droplets and/or aerosol particles that are of risk to healthcare workers, requiring heavy use of personal protective equipment. There have been recent studies indicating that self-collected saliva specimens can be used for molecular detection of SARS-CoV-2 and provides more comfort and ease of use for the patients. Here we report the performance of QuantiVirus™ SARS-CoV-2 test using saliva as the testing specimens with or without pooling. Methods Development and validation studies were conducted following FDA-EUA and molecular assay validation guidelines. Using SeraCare Accuplex SARS-CoV-2 reference panel, the limit of detection (LOD) and clinical performance studies were performed with the QuantiVirus™ SARS-CoV-2 test. For clinical evaluation, 85 known positive and 90 known negative clinical NPS samples were tested. Additionally, twenty paired NPS and saliva samples collected from recovering COVID-19 patients were tested and the results were further compared to that of the Abbott m2000 SARS-CoV-2 PCR assay. Results of community collected 389 saliva samples for COVID-19 screening by QuantiVirus™ SARS-CoV-2 test were also obtained and analyzed. Additionally, testing of pooled saliva samples was evaluated. Results The LOD for the QuantiVirus™ SARS-CoV-2 test was confirmed to be 100–200 copies/mL. The clinical performance studies using contrived saliva samples indicated that the positive percentage agreement (PPA) of the QuantiVirus™ SARS-CoV-2 test is 100% at 1xLOD, 1.5xLOD and 2.5xLOD. No cross-reactivity was observed for the QuantiVirus™ SARS-CoV-2 test with common respiratory pathogens. Testing of clinical samples showed a positive percentage agreement (PPA) of 100% (95% CI: 94.6% to 100%) and a negative percentage agreement (NPA) of 98.9% (95% CI: 93.1% to 99.9%). QuantiVirus™ SARS CoV-2 test had 80% concordance rate and no significant difference (p = 0.13) between paired saliva and NPS specimens by Wilcoxon matched pairs signed rank test. Positive test rate was 1.79% for 389 saliva specimens collected from local communities for COVID-19 screening. Preliminary data showed that saliva sample pooling up to 6 samples (1:6 pooling) for SARS-CoV-2 detection is feasible (sensitivity 94.8% and specificity 100%). Conclusion The studies demonstrated that the QuantiVirus™ SARS-CoV-2 test has a LOD of 200 copies/mL in contrived saliva samples. The clinical performance of saliva-based testing is comparable to that of NPS-based testing. Pooling of saliva specimens for SARS-CoV-2 detection is feasible. Saliva based and high-throughput QuantiVirus™ SARS-CoV-2 test offers a highly desirable testing platform during the ongoing COVID-19 pandemic.

3D visualization of the fracture surface by the series of multilevel images

The method for visualization of details on the image of the still fracture surface of impact testing specimen on the base of the series of optical microscope images with the small focus depth is proposed. A series of images of a still object was obtained by successive change of the distance to focal plane with a certain fixed step. The local contrast maximum principle was applied to images in the sequence for construction of aggregated all-in-focus image. A level map was formed from the indexes of the image in the series, which at certain pixel indicates the most probable distance to the corresponding point of the object. The Chebyshev best approximation was used for estimation of the height of the relief to provide better 3-D visualization of a three-dimensional image of the fracture surface. The area of fracture surface was estimated by train-gulation of alpha shape.

Saliva as a testing specimen with or without pooling for SARS-CoV-2 detection by multiplex RT-PCR test

BackgroundSensitive and high throughput molecular detection assays are essential during the coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The vast majority of the SARS-CoV-2 molecular assays use nasopharyngeal swab (NPS) or oropharyngeal swab (OPS) specimens collected from suspected individuals. However, using NPS or OPS as specimens has apparent drawbacks, e.g. the collection procedures for NPS or OPS specimens can be uncomfortable to some people and may cause sneezing and coughing which in turn generate droplets and/or aerosol particles that are of risk to healthcare workers, requiring heavy use of personal protective equipment. There have been recent studies indicating that self-collected saliva specimens can be used for molecular detection of SARS-CoV-2 and provides more comfort and ease of use for the patient. Here we report the performance of QuantiVirus™ SARS-CoV-2 multiplex test using saliva as the testing specimens with or without pooling.MethodsDevelopment and validation studies were conducted following FDA-EUA and molecular assay validation guidelines. Using SeraCare Accuplex SARS-CoV-2 reference panel, the limit of detection (LOD) and clinical evaluation studies were performed with the QuantiVirus™ SARS-CoV-2 multiplex test. For clinical evaluation, 85 known positive and 90 known negative clinical NPS samples were tested. Additionally, twenty paired NPS and saliva samples collected from recovering COVID-19 patients were tested and the results were further compared to that of the Abbott m2000 SARS-CoV-2 PCR assay. Results of community collected 389 saliva samples for COVID-19 screening by QuantiVirus™ SARS-CoV-2 multiplex test were also obtained and analyzed. Moreover, saliva pooling with 6 and 12 samples together were also evaluated.ResultsThe LOD for the QuantiVirus™ SARS-CoV-2 multiplex test was confirmed to be 100-200 copies/mL. The clinical evaluation using contrived saliva samples indicated that the positive percentage agreement (PPA) of the QuantiVirus™ SARS-CoV-2 multiplex test is 100% at 1xLOD, 1.5xLOD and 2.5xLOD. No cross-reactivity was observed for the QuantiVirus™ SARS-CoV-2 multiplex test with common respiratory pathogens. Testing of clinical samples showed a positive percentage agreement (PPA) of 100% (95% CI: 94.6% to 100%) and a negative percentage agreement (NPA) of 98.9% (95% CI: 93.1% to 99.9%). QuantiVirus ™SARS CoV-2 multiplex test had 80% concordance rate and no significant difference (p=0.13) in paired saliva and NPS specimens by Wilcoxon matched pairs signed rank test. Positive test rate was 1.79% for 389 saliva specimens collected from the communities for COVID-19 screening. Preliminary data showed that saliva sample pooling up to 6 samples for SARS-CoV-2 detection is feasible (sensitivity 94.8% and specificity 100%).ConclusionThe studies demonstrated that the QuantiVirus™ SARS-CoV-2 multiplex test has a LOD of 200 copies/mL in contrived saliva samples. The clinical performance of saliva-based testing is comparable to that of NPS-based testing. Pooling of saliva specimens for SARS-CoV-2 detection is feasible. Saliva based and high-throughput QuantiVirus™SARS-CoV-2 multiplex test offers a highly desirable test during the ongoing COVID-19 pandemic.

Ultrasonic and Conventional Fatigue Endurance of Aeronautical Aluminum Alloy 7075-T6, with Artificial and Induced Pre-Corrosion

Ultrasonic and conventional fatigue tests were carried out on the AISI-SAE AA7075-T6 aluminum alloy, in order to evaluate the effect of artificial and induced pre-corrosion. Artificial pre-corrosion was obtained by two hemispherical pitting holes of 500-μm diameter at the specimen neck section, machined following the longitudinal or transverse direction of the testing specimen. Induced pre-corrosion was achieved using the international standard ESA ECSS-Q-ST-70-37C of the European Space Agency. Specimens were tested under ultrasonic fatigue technique at frequency of 20 kHz and under conventional fatigue at frequency of 20 Hz. The two applied load ratios were: R = −1 in ultrasonic fatigue tests and R = 0.1 in conventional fatigue tests. The main results were the effects of artificial and induced pre-corrosion on the fatigue endurance, together with the surface roughness modification after the conventional fatigue tests. Crack initiation and propagation were analyzed and numeric models were constructed to investigate the stress concentration associated with pre-corrosion pits, together with the evaluation of the stress intensity factor in mode I from crack initiation to fracture. Finally, the stress intensity factor range threshold ΔKTH was obtained for the base material and specimens with two hemispherical pits in transverse direction.

Evaluation of Positive B- and T-Cell Gene Rearrangement Studies in Patients With Negative Morphology, Flow Cytometry, and Immunohistochemistry

Context.— The significance of positive immunoglobulin (IG) or T-cell receptor (TCR) gene rearrangement studies in the context of otherwise normal ancillary findings is unknown. Objective.— To examine long-term hematologic outcomes of individuals with positive gene rearrangement studies with otherwise unremarkable blood or bone marrow studies in parallel. Design.— Data from patients who underwent IG or TCR gene rearrangement testing at the authors' affiliated Veterans Affairs Hospital January 1, 2013 to July 6, 2018 were extracted from medical records. Date of testing, specimen source, and morphologic, flow cytometric, immunohistochemical, and cytogenetic characterization of the tissue source were recorded. Gene rearrangement results were categorized as test positive/phenotype positive (T+/P+), test positive/phenotype negative (T+/P−), test negative/phenotype negative (T−/P−), or test negative/phenotype positive (T−/P+) based on comparison to other studies and/or final diagnosis. Patient records were reviewed for subsequent diagnosis of hematologic malignancy for patients with positive gene rearrangements but no other evidence for a disease process. Results.— A total of 136 patients with 203 gene rearrangement studies were analyzed. For TCR studies, there were 2 T+/P− and 1 T−/P+ results in 47 peripheral blood assays, as well as 7 T+/P− and 1 T−/P+ results in 54 bone marrow assays. Regarding IG studies, 3 T+/P− and 12 T−/P+ results in 99 bone marrow studies were identified. None of the 12 patients with T+/P− TCR or IG gene rearrangement studies later developed a lymphoproliferative disorder. Conclusions.— Positive IG/TCR gene rearrangement studies in the context of otherwise negative bone marrow or peripheral blood findings are not predictive of lymphoproliferative disorders.