Isothermal Tests Research Articles

Chemical Heating for Minimally Instrumented Point-of-Care (POC) Molecular Diagnostics

The minimal instrumentation of portable medical diagnostic devices for point-of-care applications is facilitated by using chemical heating in place of temperature-regulated electrical heaters. The main applications are for isothermal nucleic acid amplification tests (NAATs) and other enzymatic assays that require elevated, controlled temperatures. In the most common implementation, heat is generated by the exothermic reaction of a metal (e.g., magnesium, calcium, or lithium) with water or air, buffered by a phase-change material that maintains a near-constant temperature to heat the assay reactions. The ability to incubate NAATs electricity-free and to further to detect amplification with minimal instrumentation opens the door for fully disposable, inexpensive molecular diagnostic devices that can be used for pathogen detection as needed in resource-limited areas and during natural disasters, wars, and civil disturbances when access to electricity may be interrupted. Several design approaches are reviewed, including more elaborate schemes for multiple stages of incubation at different temperatures.

Effect of agitation during the early-age hydration on thixotropy and morphology of cement paste

AbstractThe effect of agitation during the early-age hydration on thixotropy and morphology of cement paste prepared with and without superplasticizers (SP) is investigated by applying penetration test, small amplitude oscillatory shear sweep test (SAOS), isothermal calorimetric test, scanning electron microscopy (SEM) and energy dispersive X-ray analyses (EDX). The results show that the agitation of cement paste during the induction period increases the heat flow rate and destroys existing structures of samples without changing the mineral composition of samples. Yet, if the agitation is applied during the acceleration period, the heat flow rate is significantly lowered and the morphology and mineral composition of samples undergo irreversible change, freshly formed syngenite is destroyed and no longer restored. The penetration force and the static yield stress grow linearly during the induction period and exponentially during the acceleration period. Agitation during the induction period destroys the structure, which causes the static yield stress and the penetration force values becoming nearly equal to zero. However, during the acceleration period, even after agitation the static yield stress and the penetration force exhibit high residual values, which indicates the impact of hydration to the structural build-up.

Effect of the flow behavior and dynamic recrystallization of EH420 marine steel on the morphology evolution of martensite substructures

The hot deformation behavior of EH420 marine steel was investigated by isothermal compression tests in the temperature range of 850~1050°C and the strain rate range of 0.01~10s−1. A high-temperature constitutive model and a hot processing map were developed. The results indicated that the microstructure of EH420 marine steel after hot deformation was mainly bainite and lath martensite. The martensite blocks gradually coarsened with the increase in temperature within the range of 950~1050°C/0.01s-1, and the average width increased from about 0.7 μm to 2.3 μm. At high strain rates, martensite blocks became coarse and disordered due to flow instability. The flow stress curve showed a single peak when the strain rate was low. There were more dynamic recrystallization (DRX) structures, resulting in fine and ordered martensite blocks. Under the deformation conditions of 0.1~10s-1/1000°C, the proportion of high-angle grain boundaries (HAGBs) decreased from 53.5% to 40.7% as the strain rate increased. Meanwhile, the hot deformation mechanism shifted from discontinuous dynamic recrystallization (DDRX) to the combined effect of DDRX and dynamic recovery (DRV) and finally transformed into DRV. The flow stress derived from the constitutive model was consistent with the experimental results. The activation energy of EH420 marine steel was 3.16×105J/mol. The optimal hot processing parameters were 950~1050°C and 0.01~0.1s-1.

A loop-mediated isothermal amplification test for yaws: a multi-country diagnostic accuracy evaluation

To meet the WHO target of eradicating yaws by 2030, highly sensitive and specific diagnostic tools are needed. A multiplex Treponema pallidum-Haemophilus ducreyi loop-mediated isothermal amplification (TPHD-LAMP) test holds promise as a near-patient diagnostic tool for yaws and H ducreyi. We conducted a prospective evaluation in Cameroon, Côte d'Ivoire, Ghana, and the Republic of the Congo to determine the diagnostic accuracy of the TPHD-LAMP test, as well as to assess its acceptability, feasibility, and cost. Active case searching within schools and communities was used to locate participants with clinically suspicious laws-like lesions. Individuals with serologically confirmed active yaws provided paired lesion swabs between March, 2021, and April, 2023. For each participant, one swab was tested with the TPHD-LAMP at a local district laboratory and the other with reference quantitative PCR (qPCR) tests conducted at national reference laboratories. The primary outcome was TPHD-LAMP test sensitivity and specificity compared with qPCR. Laboratory technicians were interviewed using a multiple-choice survey to gauge acceptability and feasibility of the TPHD-LAMP test. Costs of each test were calculated. Of 3085 individuals with at least one suspected yaws lesion, 531 (17%) were serologically confirmed. We enrolled 493 participants with seropositive yaws and a further 32 with negative serology. The sensitivity of the TPHD-LAMP test for detecting T pallidum was 63% (95% CI 56-70) and the specificity was 66% (95% CI 61-71). Sensitivity and specificity for T pallidum improved to 73% (63-82; p=0·0065) and 75% (68-80; p=0·0003), respectively, in H ducreyi-negative samples. Interviews highlighted challenges in user-friendliness and practicality of the TPHD-LAMP test. The cost of the test per sample was one third of that of qPCR, although the TPHD-LAMP test entailed higher costs to establish the assay. This was the first multi-country diagnostic evaluation of a molecular test for yaws. The TPHD-LAMP testing, in its current form, falls short of the WHO target product profile criteria for yaws diagnostics. These findings highlight the importance of assessing new diagnostics in real-world conditions to ensure their suitability for programmatic use. The EDCTP2 programme supported by the EU.

Assessment of dwell-fatigue properties of nickel-based superalloy coated with a multi-layered thermal and environmental barrier coating

A three-layered experimental thermal and environmental barrier coating (TEBC) was deposited using air plasma spraying technology on cylindrical specimens of nickel-based superalloy MAR-M247. TEBC consists of mullite (Al6Si2O13) and hexacelsian (BaAl2Si2O8) upper layer, Y2O3 stabilised ZrO2 interlayer and CoNiCrAlY bond coat deposited on the grit-blasted surface of MAR-M247. The cyclic plastic response and damage mechanisms in uncoated and TEBC-coated MAR-M247 have been studied in isothermal dwell-fatigue tests conducted under strain control with constant strain amplitude at 900 °C. In each cycle, 5-minute dwells were introduced in both tensile and compression peaks of the hysteresis loop. Fatigue hardening/softening curves, stress relaxation curves, cyclic stress-strain curves and fatigue life curves are reported. Ceaseless mild softening has been found in both uncoated and TEBC-coated MAR-M247. TEBC-coated MAR-M247 showed an improved lifetime in the whole range of tested strain amplitudes. Data obtained from stress relaxation curves were used to assess the fraction of creep damage. The generalised damage accumulation rule was used to evaluate damage due to fatigue-creep-environment interaction. A study of the surface relief and internal microstructure using SEM and TEM helped to interpret the specifics of fatigue behaviour of uncoated and TEBC-coated material. The effectiveness of this newly developed TEBC, together with the dwell sensitivity of MAR-M247, were discussed from the perspective relevant to dwell-fatigue cyclic straining.

Investigation on the thermal deformation mechanisms and constitutive model of Ti-55511 titanium alloy

This study presents a comprehensive analysis of the hot deformation behavior of the Ti-55511 alloy over a temperature range of 700 °C to 950 °C and strain rates from 0.001 s⁻1 to 1 s⁻1, utilizing isothermal compression testing alongside electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The investigation focuses on the influence of various hot deformation parameters on the microstructural evolution of distinct phase regions within the alloy. At higher strain rates (0.1 s⁻1 to 1 s⁻1), the primary softening mechanisms for β grains in the α+β two-phase region are identified as continuous dynamic recrystallization (CDRX) and dynamic recovery (DRV), while in the β single-phase region, discontinuous dynamic recrystallization (DDRX) and DRV predominate. Conversely, at lower strain rates (0.001 s⁻1 to 0.01 s⁻1), the softening of β grains in the two-phase region is primarily governed by DRV, whereas in the single-phase region, DDRX and CDRX are the dominant mechanisms. Additionally, based on stress-strain data corrected for friction and temperature effects, an elastoplastic constitutive model is developed, incorporating strain rate and temperature to predict peak stress in the two-phase regions of the Ti-55511 alloy. This examination of the thermal deformation behavior and microstructural evolution of the Ti-55511 alloy provides significant theoretical and practical insights for optimizing the manufacturing processes of aviation die forging, tailoring microstructures, and enhancing hot working techniques.

A DNA Aptamer for 2-Aminopurine: Binding-Induced Fluorescence Quenching.

2-Aminopurine (2AP) is a fluorescent analog of adenine, and its unique properties make it valuable in various biochemical and biotechnological applications. Its fluorescence property probes local dynamics in DNA and RNA because stacking with the surrounding bases quench its fluorescence. 2AP-labeled DNA or RNA sequences have been used for the detection of genetic mutations, viral RNA, or other nucleic acid-based markers associated with diseases like cancer and infectious diseases. In this study, we isolated aptamers for 2AP using the library immobilization capture-SELEX technique. A dominating aptamer family was isolated after 15 rounds of selection. The Kd values for the most abundant 2AP1 aptamer are 209 nM in a fluorescence assay and 72 nM in an isothermal titration calorimetry test. A 32 nM 2AP limit of detection was tested based on its intrinsic fluorescence change upon aptamer binding. Additionally, we conducted some mutation analysis. Furthermore, we tested the selectivity of this aptamer and discovered that it can bind adenine and adenosine with approximately 100-fold lower affinity than 2AP.

Belite–ye’elimite–ferrite cements produced from London Clay

London Clay (LC) is generated in significant quantities from major infrastructure development projects within and around London, UK. Excavated LC spoils are typically landfilled or used for landscaping purposes with minimal value. This study investigates the feasibility of producing belite–ye’elimite–ferrite (BYF) cements using LC in combination with kaolin or low-grade bauxite. Six cement clinkers with varying compositions were synthesised at 1300°C. The phase composition of the synthesised clinkers was quantified using X-ray diffraction analysis (XRD) coupled with Rietveld refinement. The hydration behaviour, phase assemblage evolution and mechanical performance of the cements were examined using isothermal calorimetry, XRD, thermogravimetric analysis and compressive strength testing, respectively, up to 90 days of curing. It is demonstrated that LC can be used either on its own or with kaolin or low-grade bauxite to produce BYF cements with a wide range of composition: 31 to 64 wt% belite, 9.3 to 27 wt% ye’elimite and 2.1 to 31 wt% ferrite. The use of LC as the sole alumina source resulted in low compressive strength at early stages. Nevertheless, the strength developed over time, reaching 27.8 MPa at 90 days (0.5 w/b). Possible approaches to develop LC further for producing viable BYF cements are discussed.

On the Origin of Enhanced Tempering Resistance of the Laser Additively Manufactured Hot Work Tool Steel in the As-Built Condition

Abstract In laser additive manufacturing (AM) of hot work tool steels, direct tempering (DT) of the tool from as-built (AB) condition without prior conventional austenitization and quenching results in enhanced tempering resistance. To date, intercellular retained austenite (RA) decomposition, leading to a shift in secondary hardening peak temperature, and finer martensite substructure are reported to be responsible for such a behavior. In this work, authors aimed at studying the strengthening contributions by performing isothermal tempering tests for long times (up to 40 hours) at elevated temperatures (up to 650 °C) on DT and quenched and tempered (QT) specimens. The thermal softening kinetics and the microstructural evolution were evaluated with the support of computational thermodynamics. The results suggest that the main contributor to enhanced temper resistance in DT condition is the larger fraction of thermally stable and extremely fine (~ 20 nm) secondary (tempering) V(C,N) compared with QT. This could be explained by the reduction of available V and C in austenitized and quenched martensite for a later secondary V(C,N) precipitation during tempering, because of equilibrium precipitation of relatively large (up to 500 nm) vanadium-rich carbonitrides during the austenitization process. A complementary effect of the substructure refinement (i.e., martensite block width) in rapidly solidified highly supersaturated martensite was also quantified in terms of Hall–Petch strengthening mechanism. The significant effect of secondary V(C,N) was successfully validated by assessing a laser AM processed vanadium-free hot work tool steel in QT and DT condition, where no significant differences in strength and temper resistance between the two conditions were evident. Graphical Abstract

Stacking fault energy during DRV-DRX competition in high-nitrogen austenitic stainless steel used in orthopedic implants

High-nitrogen (high-N) austenitic stainless steels (ASS) are used in orthopedic implants due to their mechanical properties, human biocompatibility, and affordable cost. However, the high content of (Ni–Nb–N)-rich precipitates can cause allergic reactions and significant challenges in the manufacturing of prostheses. This study investigates the competition between work hardening (WH), dynamic recovery (DRV), and dynamic recrystallization (DRX) during the physical simulation of an ASTM F-1586 steel by thermomechanical processing, using the Kocks-Mecking and Avrami constitutive models. The parameters were obtained through continuous isothermal torsion tests at the temperature range of 900–1200 °C, strain rates between 0.01 and 10 s−1 and a total deformation of 4.0. Determined by compositional-analytical methods, the stacking fault energy (γsfe) was correlated with the stress level (σi) according to the Uesugi and Dai models. Results indicated a high activation energy for hot deformation (Qdef = 587 kJ/mol), affecting the shape of the curves. The γsfe value varied along the curves, delaying the onset of the DRX (σc = 0.928σp). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses revealed a direct competition between work-hardened and recrystallized grains in the early part of the curves, due to WH-DRV synergy. After the peak stress (σp), the progress of DRX was slow, with the Avrami exponent (n) between 1.1 and 1.9, completing only after large deformations (σss = 0.714σp). The moderate γsfe value (69 mJ/m2) and fine precipitates of the Z-phase (CrNbN) (<20 nm) influence the grain boundary mobility during the DRV-DRX competition, delineating the stress-strain curve shape.

Study on hot deformation behavior and dynamic recrystallization mechanism of recycled Al–Zn–Mg–Cu alloy

This study utilized Al–Zn–Mg–Cu alloy chips as raw materials to prepare recycled billets through a solid-state recycling process. Isothermal hot compression tests were conducted using a thermal simulation machine to establish an Arrhenius-type constitutive equation and the hot processing map based on the dynamic materials model. The microstructure of the recycled Al–Zn–Mg–Cu alloy after hot compression was characterized and analyzed using SEM, EBSD, and TEM, exploring the microstructural evolution mechanisms of the recycled alloy at different temperatures and strain rates. The results indicate that the optimal hot deformation parameters for the recycled Al–Zn–Mg–Cu alloy are 300–360 °C at a strain rate of 0.01–0.05 s⁻1 and 400–450 °C at a strain rate of 0.05–0.3 s⁻1. At the same strain rate, as the deformation temperature increases, low-angle grain boundaries gradually disappear, and the grain structure becomes more stable. Dynamic recrystallization replaces dynamic recovery as the dominant mechanism. At the same deformation temperature, low strain rates allow more time for the migration of low-angle grain boundaries, thereby promoting the growth of dynamically recrystallized grains and ultimately forming new, undistorted grains.

Development of a Spot Test (ST) Based on the Nucleic Acid Amplification Test (NAAT) for Ginseng Species Authentication

It is very challenging to distinguish between Panax ginseng (P. ginseng) and Panax quinquefolius (P. quinquefolius) based on their physical appearances. Therefore, a molecular test that can be performed in commercial settings is needed to address this challenge. We have selected a locus containing a single nucleotide polymorphism (SNP) site in the Dammarendiol-II Synthase (DS) gene to differentiate between P. ginseng and P. quinquefolius. An isothermal nucleic acid amplification test (NAAT) developed previously was adapted and used on a spot test (ST) format consisting of a sample pad, a nitrocellulose membrane, and an adsorbent pad. An ST with a colorimetric detection method has been developed with visual detection based on 20-nm gold nanoparticles. The presence of the target DNA will generate a red color signal, which is visible to the naked eye. The assay comprises the capture probes, constructed based on the DS gene of ginseng, and the ends of the probe sequences sit on the SNP site for the P. ginseng and P. quinquefolius sequences; the detection probe employed in the assay is tagged with gold. The NAAT amplifies the extracted plant genomic samples and enhances the detection of specific SNPs. This NAAT technique was used to authenticate two ginseng root samples, showing greater specificity ratios than our previous work.

Optimization method of parameters inverse identification for hot deformation constitutive model of 2Cr13 martensitic stainless steel using genetic algorithm

Constitutive models are considered a key prerequisite to investigate the thermal deformation behavior of materials. Accurate identification of their parameters is crucial for enhancing the predictive precision of the models. A novel optimization method for accurate inverse identification of parameters using the genetic algorithm (GA) in the Modified Zerilli-Armstrong (MZA) model was proposed in this work. Under conditions of temperatures ranging from 1223 K to 1473 K at intervals of 50 K and strain rates of 0.01, 0.1, 1, and 5 s−1, uniaxial isothermal hot compression tests were performed on 2Cr13 martensitic stainless steel (MSS) employing a Gleeble-1500D thermal simulation test machine. Based on the experimental data, the conventional linear regression method was utilized to solve the MZA model of 2Cr13 MSS. Initial values for the material constants I1, S1, C5, and C6 to be optimized were assigned drawing from the calculated results. The GA-based iteratively optimized MZA (G-ZA) model was established by minimizing the mean squared error as an objective function between the experimental and predicted flow stress values. Compared to the MZA model, a significant enhancement in predictive performance was achieved with the G-ZA model, while good generalization was also demonstrated. Both models were successfully integrated into the Forge® finite element analysis software through the secondary development of user subroutines. Numerical simulation results indicated that the G-ZA model demonstrated a better agreement with the experimental data in predicting the load-displacement curve. This validated that a more accurate constitutive model for the hot deformation of 2Cr13 MSS can be effectively constructed using the GA-based parameter inverse identification strategy.

Real-Time Visualization of HIV-1 RNA Detection Using Loop-Mediated Isothermal Amplification-Enabled Particle Diffusometry.

Isothermal nucleic acid amplification tests, NAATs, such as reverse transcription-loop-mediated isothermal amplification (RT-LAMP), offer promising capabilities to perform real-time semiquantitative detection of viral pathogens. These tests provide rapid results, utilize simple instrumentation for single-temperature reactions, support efficient user workflows, and are suitable for field use. Herein, we present a novel and robust method for real-time monitoring of HIV-1 RNA RT-LAMP utilizing a novel implementation of particle diffusometry (PD), a diffusivity quantification technique using fluorescent particles, to quantify viral concentration in nuclease-free water. We monitor changes in particle diffusion dynamics of 400 nm fluorescently labeled particles throughout the RT-LAMP of HIV-1 RNA in nuclease-free water, enabling measurement within 20 min and detection of concentrations as low as 25 virus particles per μL. Moreover, in a single-blind study, we demonstrate semiquantitative detection by accurately determining the initial concentration of an unknown HIV-1 RNA within a 10% absolute error margin. These results highlight the potential of real-time PD readout for quantifying HIV-1 RNA via RT-LAMP, offering promise for viral load monitoring of HIV and other chronic infections.

The Recombinase Polymerase Amplification Test for Strongyloides stercoralis Is More Sensitive than Microscopy and Real-Time PCR in High-Risk Communities of Cusco, Peru.

Strongyloidiasis is a neglected, soil-transmitted helminth infection prevalent worldwide. The true burden of strongyloidiasis is unclear due to the lack of sensitive, field-friendly diagnostic tests. PCR tests to detect Strongyloides DNA in stool are sensitive and specific, but the need for expensive equipment limits their use in endemic regions. Isothermal PCR amplification tests are easier to deploy while maintaining sensitivity and specificity. We developed and evaluated a recombinase polymerase amplification lateral flow assay (RPA-LFA) to detect Strongyloides stercoralis in human stool samples. Three hundred stool samples were collected in three communities in the jungle of Cusco, Peru. Samples were tested for S. stercoralis larvae using microscopy (Baermann's, agar plate culture (APC), and rapid sedimentation), real-time PCR, and RPA-LF for Strongyloides DNA. The RPA-LFA showed an analytical limit of detection of 20 pg/µL. The prevalence of S. stercoralis was 27%, 38%, 46.3%, and 46% using microscopy, PCR, microscopy/PCR, and RPA-LFA, respectively. RPA-LFA had a sensitivity and specificity of 59.3% and 58.9%, 66.2% and 71.4%, and 77.2% and 73.1% when microscopy, microscopy/PCR, and real-time PCR were used as the gold standards, respectively. The Strongyloides RPA-LFA is a novel, fast, highly sensitive, and specific molecular method with the potential for deployment in endemic regions.

Liquid AlCoCrFeNi and AlCoCrFeNiX (X = Mo, Ta) high-entropy alloys on graphite: Wetting, reactivity and CALPHAD modelling

Wettability and interfacial reactivity with graphite of three equimolar High-Entropy Alloys (HEAs), namely AlCoCrFeNi (HEA-base), AlCoCrFeNiMo (HEA-Mo) and AlCoCrFeNiTa (HEA-Ta), were investigated for the first time, aiming to support industrial sectors involving liquid-phase processing routes. Isothermal high-temperature wettability tests were performed at 1400 °C for HEA-base and HEA-Mo, and at 1580 °C for HEA-Ta. The samples were then analysed by SEM-EDS. Based on the in-house-built GHEA thermodynamic database, CALPHAD calculations were used to simulate and discuss liquid-solid interactions occurring at high temperatures as well as transformations taking place in the samples during cooling. HEA-base wetted the graphite well after 5 min and the wetting behaviour significantly improved for HEA-Mo after the same contact time. HEA-Ta, after initial melting and wetting stage, solidified due to high-melting phases formation. All the graphite/HEA samples formed refractory carbides. For HEA-base and HEA-Mo, such carbides were found homogeneously dispersed in the whole drop. In HEA-Ta, TaC formed a compact layer separating two liquids of different compositions, with only one of these being in contact with the graphite substrate. The here proposed combination of experiments and thermodynamic calculations allowed to understand and discuss both high-temperature reactivity and evolution of the systems over cooling. Overall, a remarkable agreement between equilibrium calculations and experimental findings was observed for these complex dynamic systems.

A-251 Simplification of Molecular Diagnostics for Sexually Transmitted Infection Point-of-Care Testing

Abstract Background HPV-caused cancers contribute to a large disease burden, accounting for 5% of all cancers. It is estimated that over 700,000 people develop HPV-related cancers each year with the majority being cervical cancer. The burden of this disease is disproportionately carried by low-income countries with the highest rates of HPV cervical infections primarily found in sub-Saharan Africa, Latin America, Eastern Europe, and South-East Asia. Many regions in low-resource countries lack adequate access to sensitive point-of-care screening tools, preventing timely diagnosis and treatment. Current low-cost methods, such as Pap smears and visual inspection using acetic acid suffer from low sensitivity, specificity, and reproducibility which limit their effectiveness as a screening modality. Many countries use nucleic acid amplification tests (NAATs) to identify key HPV infections which may progress towards cervical cancer. However, the expenditure for NAAT-capable equipment and reagents are cost-prohibitive for rural and underserved communities. To reduce screening barriers, we developed an isothermal HPV molecular test that can detect all 14 cancer-causing HPV strains using a novel amplification methodology combined with G-quadruplex DNAzyme colorimetric detection. Methods We developed a novel isothermal amplification technique that is related to loop-mediated isothermal amplification (LAMP) but uses modified looped primers to enable exponential amplification at 60°C for 1 hour. The modified primers only require two binding sites compared to 4-6 in LAMP. To detect the amplified products, we used G-quadruplex peroxidase-like DNAzyme probes which reduce ABTS to produce a visually interpreted result. Analytical validation evaluated the method’s limit of detection, specificity, and accuracy. As proof of concept in a relevant matrix, clinical cervical brushings collected ThinPrep Pap media were tested with the new method and compared to an FDA-approved reference qPCR test. Results Repeated experiments demonstrate that the lowest detectable HPV DNA concentration was approximately 1000 genomic copies/µL with no amplification with other pathogens. As proof of concept, the comparison to the reference standard demonstrated high accuracy. Conclusions The application of our assay is intended as a near-patient screening tool with further evaluation by a clinician for confirmation. With an accurate and rapid screening tool, we envision low-resource regions across the world will have the tools to rapidly detect and treat cervical cancers in their early stages.

Supercritical Methane Adsorption Characteristics and Pore Structure Characteristics of Deep Middle Rank Coal

Abstract In order to accurately analyze the adsorption characteristics, pore structure, and fractal law of deep middle rank coal, high-pressure isothermal adsorption tests based on magnetic levitation high-pressure thermobalance and pore structure tests based on mercury intrusion method were carried out on coal samples collected from typical kilometer level deep wells. The fractal law of sponge model was studied. The results showed that: a. The weight method adsorption test showed “excess adsorption” phenomenon with the increase of equilibrium pressure, and the modified Gibbs surface excess adsorption theory was in line with the Langmuir adsorption model; b. The distribution of macropore volume in deep middle rank coal accounts for a dominant proportion of 57.44% to 62.47%, and the proportion of microporous specific surface area reaches 72.96% to 74.27%, indicating that microporous adsorption capacity is the strongest; c. The pore structure parameters and adsorption constants exhibit strong nonlinear characteristics.

A comparative study of hot tensile deformation behavior of 6016 aluminum alloy under LSTM neural network and Arrhenius model

Abstract The isothermal tensile test of 6016-T6 aluminum alloy was carried out on Gleeble-3500 at the temperature range of 400 °C–550 °C and the strain rate range of 0.01–10 s−1. The results show that the thermal deformation mechanism of 6016-T6 is dynamic recovery and dynamic recrystallization. In this paper, the phenomenological Arrhenius constitutive model and the data-driven WOA-LSTM constitutive model for predicting the hot tensile deformation behavior of 6016-T6 aluminum alloy were studied in contrast. The whale optimization algorithm was used to optimize the hyperparameters of LSTM neural network to improve the prediction accuracy of flow stress. The optimization results show that the optimal hidden layer node, maximum training period, initial learning rate and mini batch size of WOA-LSTM are 46, 260, 0.0248 and 16, respectively. In addition, the influence of the number of hidden layers on the results of the network was discussed. The appropriate hidden layer of the network was determined to be 2. The result show that the prediction accuracy of WOA-LSTM constitutive model is better than the Arrhenius constitutive model. The mean absolute error and correlation coefficient are 0.9348% and 0.99952, respectively. Among them, in this study, the Arrhenius constitutive model has low precision and only has high precision within a single temperature range.

Enhancing the Accuracy of Peripheral Pulmonary Tuberculosis Diagnosis: A Comparative Evaluation of CapitalBioTM Mycobacterium Nucleic Acid Detection Test and Mycobacterium tuberculosis Isothermal RNA Amplification Assay Using Endobronchial Ultrasonography with Guide Sheath.

The diagnosis of tuberculosis located in the peripheral zone remains challenging and requires ultrasound bronchoscopy-guided maneuvers. We assessed the precision of CapitalBioTM Mycobacterium nucleic acid detection test (CapitalBio MTB test) and Mycobacterium tuberculosis isothermal RNA amplification test (MTB-RNA) using endobronchial ultrasonography with a guide sheath (EBUS-GS) for peripheral pulmonary tuberculosis (PTB) and compared it with those of acid-fast bacilli (AFB) smear and MTB culture tests. This retrospective analysis included 287 patients suspected of peripheral pulmonary tuberculosis who underwent EBUS-GS examinations, medical examination results of AFB smears, MTB culture, CapitalBio MTB test, and MTB-RNA were analyzed. We evaluated the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic curve (AUC), and its diagnostic accuracy for peripheral PTB was evaluated in comparison with the final clinical diagnosis. The overall sensitivity, specificity, PPV, NPV, and AUC of CapitalBio MTB test were 44.83%, 100.00%, 100.00%, 54.07%, and 0.72, respectively; those of MTB-RNA were 22.99%, 100.00%, 100.00%, 45.75%, and 0.61, respectively, and those for parallel test (CapitalBio MTB test or MTB-RNA) were 46.55%, 100.00%, 100.00%, 54.85%, and 0.73, respectively. These values for AFB smear were 9.2%, 97.35%, 84.21%, 41.04%, and 0.53, respectively, and those of MTB culture were 31.03%, 100.00%, 100.00%, 48.50%, and 0.69, respectively. The CapitalBio MTB test showed the best diagnostic performance compared with AFB smear, MTB culture, and MTB-RNA assays and was similar to the parallel test (CapitalBio MTB test or MTB-RNA). The CapitalBio MTB test combined with EBUS-GS had satisfactory diagnostic accuracy for diagnosing peripheral PTB.