Split Test Research Articles

Experimental study on flexural fatigue resistance of fiber-reinforced sustainable walnut shell ash mortar

In recent research on building materials, researchers have increasingly focused on replacing cement with agricultural waste. This approach offers significant advantages in terms of reducing global CO2 emissions and promoting the sustainability of building materials. In this paper, the use of the agricultural waste walnut shell ash (WSA) to partially replace cement in sustainable green mortars is explored. Specifically, equal amounts of WSA (5%, 10% and 15%) were used to replace cement. To offset the reduction in strength caused by the partial replacement of cement with WSA, basalt fibers were added to the mortar mixture. The effect of these fibers on the mechanical properties of the WSA-reinforced mortar was examined in compression tests, split tensile tests, and flexural fatigue cycle tests. In the flexural fatigue tests, the parameter and length of basalt fibers were varied and different stress levels (0.85, 0.8 and 0.75) were applied. The fatigue equations were developed using the Weibull model and p–s–n curves with a survival probability of 0.5 were derived. The results showed that the compressive strength and split tensile strength of the specimens increased with the addition of basalt fibers, with maximum values of 34.7 MPa and 3.8 MPa, respectively, and maximum increases of 8.78% and 21.95%, respectively. In addition, the average fatigue life of WSA mortar was 247,541 cycles, which increased by 139.26% when the stress level was 0.75, fiber length was 9 mm, and dosage was 0.3%. The linear regression fitting showed good correlation and provided valuable insights for practical engineering applications.

Fracture Characteristics and Tensile Strength Prediction of Rock–Concrete Composite Discs Under Radial Compression

To investigate the fracture mechanism of rock–concrete (R–C) systems with an interface crack, Brazilian splitting tests were conducted, with a focus on understanding the influence of the interface crack angle on failure patterns, energy evolution, and RA/AF characteristics. The study addresses a critical issue in rock–concrete structures, particularly how crack propagation differs with varying crack angles, which has direct implications for structural integrity. The experimental results show that the failure paths in R–C disc specimens are highly dependent on the interface crack angle. For crack angles of 0°, 15°, 30°, and 45°, cracks initiate from the tips of the interface crack and propagate toward the loading ends. However, for angles of 60°, 75°, and 90°, crack initiation shifts away from the interface crack tips. The AE parameters RA (rise time/amplitude) and AF (average frequency) were used to characterize different failure patterns, while energy evolution analysis revealed that the highest percentage of energy consumption occurs at a crack angle of 45°, indicating intense microcrack activity. Moreover, a novel tensile strength prediction model, incorporating macro–micro damage interactions caused by both microcracks and macrocracks, was developed to explain the failure mechanisms in R–C specimens under radial compression. The model was validated through experimental results, demonstrating its potential for predicting failure behavior in R–C systems. This study offers insights into the fracture mechanics of R–C structures, advancing the understanding of their failure mechanisms and providing a reliable model for tensile strength prediction.

Theoretical and experimental study on the mechanical measurement of rock tensile fracture by ring radial compression

Conventional Brazilian disc splitting tests are hampered by stress concentration at the loading points, leading to test outcomes that do not truly represent the engineering failure strength of rocks. To enhance the accuracy of these tests, the specimen shape has progressed from the Brazilian disc to a circular ring. This study presents a theoretical analysis of the compression deformation process in circular rings, followed by platform-radial compression tests conducted on various types of rocks and metals, employing the digital speckle correlation method alongside an improved mechanical extensometer. The findings indicate that circular ring specimens failed under a combination of tensile and compressive stresses. The main crack originates along the loading direction on the inner wall of the ring and propagates outwards, resulting in the failure of the entire ring structure. While maximum tensile strain may serve as an indicator of rock failure, tensile stress alone should not be considered a definitive criterion for failure.

Impact of plastic waste fiber and treated construction demolition waste on the durability and sustainability of concrete

This study explores the mechanical and durability properties of Plastic-Fibre Reinforced Concrete, incorporating hand-shredded plastic fibers sourced from polyethylene bags and PET bottles. Evaluations, including compressive and split tensile strength tests, were conducted on M40 grade mixes containing plastic fibers and 100% treated Construction and Demolition Waste (CDW), comparing them with conventional concrete. The results demonstrate a significant enhancement in strength properties with the addition of 0.25%, 0.5%, 0.75%, and 1% plastic-fibres, alongside the complete replacement of coarse aggregate with CDW, particularly noticeable at both 7 and 28-day curing ages. Although higher fiber dosages led to a slight reduction in compressive by 7% at the optimum percentage of 0.25% of PE and 0.5% of PET, the flexural strengths and split tensile strength exhibited a proportional increase of 11.7% and 18%. Surface analysis via Scanning Electron Microscopy (SEM) and elemental composition determination using Energy Dispersive Spectroscopy (EDS) revealed minimal fiber damage post-exposure, confirming its efficiency and contribution to higher strength and reduced weight loss in optimum mix. This novel approach combines manually recycled plastic waste as fibers with treated CDW, enhancing concrete properties while promoting sustainability. Sustainability analysis indicates that utilizing 100% CDW and plastic fiber contributes to reduced energy consumption, lower carbon emissions, and economic benefits. These findings underscore the potential of integrating non-degradable plastics into concrete mixtures, combined with treated CDW, offering both environmental sustainability and enhanced performance advantages in construction materials.

Evaluation of SMA-13 Asphalt Mixture Reinforced by Different Types of Fiber Additives

This research aims at systematically evaluating the properties of SMA-13 asphalt mixture reinforced by several fiber additives including flocculent lignin fiber (FLF), granular lignin fiber (GLF), chopped basalt fiber (CBF), and flocculent basalt fiber (FBF). Firstly, the thermal stability, moisture absorption, and oil absorption property of these fiber additives were analyzed. Secondly, the property of SMA-13 reinforced using four types of single fibers and two kinds of composite fibers (FLF + CBF and FLF + FBF) was comprehensively analyzed. Specifically, the high-temperature performance was evaluated using the uniaxial penetration test and the rutting test, the medium-temperature anticracking property was evaluated using the IDEAL-CT test, the low-temperature property was analyzed using the beam bending test, and the water stability was studied by the freeze–thaw splitting test. Thirdly, the dynamic mechanical response of different-fibers-modified SMA-13 was evaluated using the uniaxial compression dynamic modulus test. Finally, correlation analysis between the results of dynamic modulus and the high-, medium-, and low-temperature mechanical performance was carried out. The research results reveal that the stability of CBF and FBF under thermal action is better than that of GLF and FLF, and FBF shows the best thermal stability. The oil absorption property of FLF is better than that of GLF, followed by FBF and CBF. The comprehensive mechanical properties of CBF- and FBF-reinforced SMA-13 are better than those of FLF- and GLF-modified SMA-13. CBF can better reinforce the mechanical property of SMA-13 under low and medium temperature, while FBF can better reinforce the performance of SMA-13 at high temperature. FLF/CBF- and FLF/FBF-composite-modified SMA-13 show better high-temperature mechanical performance than that of the single-fiber-reinforced mixture, and FLF has some negative impact on the properties of FLF/FBF-composite-modified SMA-13 at low temperature. Fibers have no significant influence on the water stability of the mixtures. Meanwhile, the linear correlation between the mechanical performance of all the fiber-reinforced SMA-13 and the dynamic modulus result is good.

Infrared temperature distribution characteristics and state assessment method of sandstone under tension and compression stress

Abnormalities in infrared radiation temperature (IRT) often accompany the loading In this investigation, stress experiments and splitting tests were conducted on sandstone to investigate the IRT characteristics of sandstone under various loading conditions. The results shows that the Maximum Infrared Radiation Temperature (MAXIRT) increases by up to 5 °C, while in splitting tests, the minimum infrared radiation temperature (MINIRT) decreases by approximately 1.5 °C. Compared to the average infrared radiation temperature (AIRT), MAXIRT is more sensitive to compressive stress, whereas (MINIRT) is more responsive to tensile stress. The correlation between IRT indicators and stress were further analyzed. The findings reveal a positive correlation between IRT and compressive stress. At low stress levels, the correlation coefficient fluctuates between −0.4 and 0.6, generally showing low correlation. As stress increases, the correlation coefficient rises, reaching above 0.8, indicating a high correlation. Tensile stress exhibits a negative correlation, with a consistent trend. Additionally, a statistical analysis of the frequency distribution of IRT under different stress conditions was conducted, followed by hypothesis testing. The results demonstrate that the probability distribution of IRT during loading follows a skewed normal distribution. The changes in skewness can be divided into three stages: initial fluctuation, stable variation, and abrupt failure. Under compressive stress, a right-skewed distribution is observed, with skewness exceeding 3.5 before fracture and reaching above 10 near fracture. Under tensile stress, a left-skewed distribution is noted, with skewness reaching −4.5 near fracture. These findings contribute to the assessment of rock stress states and provide early warning information for predicting rock failure.

Dynamic splitting tensile properties of high-strength ultrahigh-toughness cementitious composites (HS-UHTCCs)

In this study, the splitting tests were conducted to examine the effect of strain rate on the splitting tensile performance of high-strength ultrahigh-toughness cementitious composites (HS-UHTCCs). Hydraulic machine and split Hopkinson pressure bar (SHPB) were used to investigate the tensile properties of HS-UHTCCs. The strain rates ranged from 10-6 to 10-3 s−1 for hydraulic machine experiments and from 5 to 15 s−1 for SHPB tests, respectively. The splitting tensile strength, tensile stress-strain curves, dynamic increase factor (DIF) and energy absorption ability of HS-UHTCCs were analyzed. The new DIF models proposed for HS-UHTCCs fit well with the experimental data. In addition, the failure modes of specimens and fibers were investigated. The splitting tensile strain was obtained from digital image correlation (DIC) tests. The results indicate that the strain rate has a significant effect on the splitting tensile strength and energy absorption ability of HS-UHTCCs. On the contrary, the average splitting tensile strain showed a decreasing trend with the increase of strain rate. Besides, the DIF model of HS-UHTCCs was proposed with experimental data. The failure modes of specimens changed at high strain rates, transitioning from remaining intact to completely splitting into half. Two failure patterns of polyethylene (PE) fibers included pull-out failure and rupture were observed, while steel fibers experienced pull-out failure.

Influence of Basalt Fiber Morphology on the Properties of Asphalt Binders and Mixtures.

Basalt fiber (BF) has been proven to be an effective additive for improving the properties of asphalt mixtures. However, the influence of basalt fiber morphology on the properties of asphalt binders and mixtures remains inadequately explored. In this study, chopped basalt fiber (CBF) and flocculent basalt fiber (FBF) were selected to make samples for testing the influence of the two types of basalt fibers on asphalt materials. Fluorescence microscopy was used to obtain the dispersion of fiber in asphalt binders. Then, a temperature sweep test and a multiple stress creep recovery (MSCR) test were carried out to appraise the rheological characteristics of the binder. Moreover, the performance of the fiber-reinforced asphalt mixture was evaluated by a wheel tracking test, a uniaxial penetration test, an indirect tensile asphalt cracking test (IDEAL-CT), a low-temperature bending test, a water-immersion stability test, and a freeze-thaw splitting test. The results indicate that the rheological behavior of asphalt binders could be enhanced by both types of fibers. Notably, FBFs exhibit a larger contact area with asphalt mortar compared to CBFs, resulting in improved resistance to deformation under identical shear conditions. Meanwhile, the performance of the asphalt mixture underwent different levels of enhancement with the incorporation of two morphologies of basalt fiber. Specifically, as for the road property indices with FBFs, the enhancement extent of DS in the wheel tracking test, that of RT in the uniaxial penetration test, that of the CTindex in the IDEAL-CT test, and that of εB in the low-temperature trabecular bending test was 3.1%, 6.8%, 15.1%, and 6.5%, respectively, when compared to the CBF-reinforced mixtures. Compared with CBFs, FBFs significantly enhanced the elasticity and deformation recovery ability of asphalt mixtures, demonstrating greater resistance to high-temperature deformation and a more pronounced effect in delaying the onset of middle- and low-temperature cracking. Additionally, the volume of the air void for asphalt mixtures containing FBFs was lower than that containing CBFs, thereby reducing the likelihood of water damage due to excessive voids. Consequently, the moisture susceptibility enhancement of CBFs to asphalt mixture was not obvious, while FBFs could improve moisture susceptibility by more than 20%. Overall, the impact of basalt fibers with different morphologies on the properties of asphalt pavement materials varies significantly, and the research results may provide reference values for the choice of engineering fibers.

Introducing the mineral powder to strengthen polyurethane grouting materials for crack repair of asphalt pavements

Cracking in asphalt pavement may lead to structural distress while existing crack repair materials have significant shortcomings in terms of cost and construction efficiency. This study incorporates mineral powder into the polyurethane grouting materials to provide a more economical and durable solution for repairing cracks in asphalt pavement. The results of bonding and tensile tests show that excessive mineral powder may deteriorate the mechanical properties of polyurethane grouting materials, which is caused by the agglomeration of mineral powder observed by the microscale characterization. Characterization tests indicate that ultraviolet exposure results in the evolution of the chemical components and thermal stability of polyurethane grouting materials, subsequently causing the degeneration in the mechanical properties. The addition of mineral powders was found to increase the tensile strength of polyurethane grouting materials after Ultraviolet aging by 12 %, while the elongation at break measured in tensile tests remained essentially unchanged. The results of the splitting test, bending test, and immersion Marshall test prove the enhanced low-temperature property and moisture resistance of mineral powder-modified polyurethane grouting materials as compared to the styrene-butadiene-styrene emulsified asphalt. The economic analysis shows that this study presents a practical approach to cost-effective asphalt pavement crack repair, offering insights for enhancing the durability of asphalt pavements.

Incentivization of Sexually Transmitted Infection Testing at a Large Public University

Abstract Background According to the United States (U.S.) Centers for Disease Control and Prevention, more than 2.5 million cases of syphilis, gonorrhea, and chlamydia were reported in 2022, with notable increases in gonorrhea and chlamydia. The highest rates of chlamydia, gonorrhea, and syphilis were found in men and women of college age. This study compared free STI testing events to usual care with regard to patient socio-economic factors and testing positivity rates. Methods The Department of Student Health & Wellness at a large, public university offers routine testing at a low cost, flat rate, including chlamydia, gonorrhea, hepatitis C Ab, syphilis and HIV testing. Two weeks of free testing were held during calendar year 2023. Utilization and positivity rates between free testing and regular testing weeks were compared using Pearson’s chi squared and Fisher Exact tests. Results A total of 8705 tests were performed during routine testing weeks with associated cost averaging 174 tests per week as compared to 1177 tests for the free testing weeks averaging 589 tests per week. Testing uptake during free testing weeks was higher among females (65.6% (n = 772) vs. 55.1% (n = 4797); p < 0.001) and minorities such as, Black or African American [11.3% (n = 133) vs. 9.4% (n = 813); p = 0.02], Hispanic [11.4% (n = 134) vs. 9.2% (n = 798); p = 0.02] and Asian [13.1% (n = 154) vs. 8.8% (n = 763); p < 0.001] when compared to testing during regular weeks. Chlamydial infection positivity rate was lower during the free testing weeks [1.8% (n = 7)] vs. [3.9% (n = 123); p = 0.04]. Gonorrhea, hepatitis C, HIV, and Syphilis positivity rates did not differ between the two testing periods. Conclusions Free STI testing in the context of a large, public university Student Health Department shows increased utilization. The establishment of free testing weeks was associated with an increase in female students and minorities use of testing services at a large public university. Key messages • Incentivization can improve STI testing utilization among university students. • The establishment of STI free testing periods can increase the use of testing services among minority students and females.

Assessing pavement characteristics: An in-depth evaluation of waste engine oil and Buton rock asphalt composite modified asphalt and its mixture

To investigate the cooperative influence of waste engine oil (WEO) and Buton rock asphalt (BRA) on asphalt characteristics, the WEO/BRA composite modified asphalt and its mixture with varied dosages were prepared. The high-, moderate-, and low-temperature assessments of WEO/BRA composite modified asphalt were conducted through temperature sweep tests, multiple stress creep and recovery (MSCR), and bending beam rheometer (BBR) tests. The softening point difference was used to analyze the storage stability of composite modified asphalt. Based on the Fourier transform infrared spectroscopy (FTIR) and fluorescence microscope (FM) test, the microscopic feature and chemical constitution of WEO/BRA composite modified asphalt were analyzed. Rutting test, low-temperature bending test, immersed Marshall test, freeze-thaw splitting test, and four-point fatigue bending test were carried out to verify the pavement properties of the WEO/BRA composite modified asphalt mixture. The results indicated that WEO improved the capability in low-temperature conditions and fatigue properties of asphalt modified with BRA. BRA enhanced the high-temperature property of asphalt modified with WEO. The synergistic effect of WEO, BRA, and neat asphalt was a physical reaction, and these modifiers were uniformly distributed in the asphalt. Meanwhile, WEO/BRA composite modified asphalt had excellent storage stability for the single modified asphalt. The test results of the asphalt mixture verified the results, indicating that WEO/BRA composite modified asphalt can be considered a new green and durable asphalt pavement material.

Simple solution immersion for realizing bifunctional catalyzation of water splitting in various electrolytes

Developing cost-effective, highly efficient and scalable bifunctional electrocatalysts for hydrogen production is crucial for advancing hydrogen energy systems. However, current methods are hindered by high energy consumption and material limitations. This work introduces a bifunctional electrocatalyst (NiFe-OH@Co2P@NF), by simply immersing a hierarchical cobalt phosphide electrode in mixed Ni/Fe solution, followed by forming layered nickel-iron hydroxides on the surface. Electrochemical tests reveal that this catalyst enhances active site exposure, accelerates electron transfer, and significantly lowers the overpotential for water electrolysis. It requires minimal overpotentials (79 mV at 10 mA cm−2, 175 mV at 150 mA cm−2) in 1 M KOH solution. In a dual-electrode electrolytic cell system, the catalyst enables efficient hydrogen production at a current density of 10 mA cm−2 with just 1.52 V, demonstrating robust stability during prolonged alkaline water splitting tests. Moreover, the bifunctional electrodes display good performance and durability in simulated alkaline seawater and 1 M KOH + seawater.

Effect of Recycled Asphalt Mixture and Solid Waste-Based Solidification Materials on Performance of Cold-Regenerated Asphalt Mixture

In this study, an aging asphalt mixture was regenerated by a waste-based rejuvenator and cemented by solid waste-based solidification materials (SSMs). A splitting test, wheel tracking test, and three-point bending test were conducted to evaluate the properties of the regenerated asphalt mixture (RAM). The results reveal that the properties of the asphalt mixture were not diminished or were moderately enhanced by the 30% substitution of RAP. With the substitution of RAP to 100%, the splitting tensile strength, dynamic stability, and splitting strength ratio were decreased by 13%, 15%, and 5%, respectively. With the 100% substitution of SSMs for cement, the compressive strength, dynamic stability, flexural strain, and splitting strength ratios of the RAM were increased by 40%, 32%%, 14%, and 8%, respectively. The lightweight components can be supplemented, and low-temperature deformation and interlayer flowability can be improved by the incorporation of the rejuvenator. The generation of hydrated calcium silicate and ettringite for SSMs is greater than those of cement. The massive generation of ettringite has been observed to increase the solid phase volume by 120%, which may facilitate a more complete filling of the remaining pores in the RAM due to water evaporation. The regeneration and cement on green and the high performance of the rejuvenator and the SSM markedly enhanced RAM performance.

Outcomes of acetaminophen infusion on visual analogue scale with varying pain intensity during labour, A randomized controlled trial

Objective: Acetaminophen (Paracetamol) is the most widely used analgesic. We aimed to determine its efficacy in labour with varying pain intensity, to make labour less painful for women. Methods: This randomized controlled trial was conducted on primigravida’s in their active phase of first stage of labour at Pharmacology department of Army Medical College, National University of Medical Sciences in collaboration with Gynecology department of Pak Emirates Military hospital, Rawalpindi. It was a registered trial with trial number of IRCT20220308054220N1. Duration of study was from May 2022 to October 2022. Patients were divided into two groups, Group-I received two doses of I/V 100 ml normal saline whereas Group-II received I/V two doses of 1000 mg acetaminophen in 100 ml normal saline. Calculated sample size was 130, 65 in each group. Visual analogue scale was used as a tool for data measurement. Data was analysed using split plot anova test. Results: Mean VAS in acetaminophen infusion group was found to be less than placebo for 1st dose, but this effect was apparent only one hour after 2nd dose intervention. The difference in means between groups was statistically significant only for 1st dose with p-value of 0.003 (for second dose p-value 0.21). In acetaminophen infusion group, for both doses mean VAS decreased as an immediate effect of drug, but then it increased with time. The difference in VAS between intervals had p-value of <0.001 for 1st dose and 0.005 for 2nd dose. Conclusion: Acetaminophen is an effective non opioid labour analgesic in active phase of first stage of labour. doi: https://doi.org/10.12669/pjms.40.10.8425 How to cite this: Najeeb W, Komal N, Noor M, Khan MA, Chaudry A. Outcomes of acetaminophen infusion on visual analogue scale with varying pain intensity during labour, A randomized controlled trial. Pak J Med Sci. 2024;40(10):2163-2169. doi: https://doi.org/10.12669/pjms.40.10.8425 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Utilization of thermoplastic resin as foamed asphalt modifier in cold recycled mixtures

The utilization of foamed virgin asphalt in cold recycled mixtures results in insufficient bonding strength between aggregates, leading to rapid deterioration to the recycled asphalt pavement. This ultimately causes inefficient clean production and increased carbon emissions. The foaming performance of thermoplastic resin modified asphalt (TRA) under different foaming conditions was analyzed. Micro-scale chemical and physical tests were utilized to discover the foaming mechanism of TRA. The road performance of cold recycled mixtures with foamed TRA was evaluated through splitting, rutting and fatigue tests. The results showed that the increase in the TRA polar functional group index led to an increase in its surface tension, thus limiting its expansion capacity. However, the increase in the specific heat capacity of TRA indicated that it preserves a low viscosity level essential for its foaming efficacy post-ejection from the foaming machine, thereby enhancing its half-life. Furthermore, the dynamic viscosity of the TRA with an 8% thermoplastic resin dosage exceeded 40000 Pa s at 60 °C, meeting the specification requirements for high viscosity asphalt, while exhibiting a notably lower viscosity of only 120 mPa s at the foaming temperature of 170 °C. The observed low viscosity of the asphalt is anticipated to favorably enhance the formation of a stable foam structure. The mechanical properties and overall road performance of the cold recycled mixture with foamed TRA were significantly enhanced, especially in terms of moisture damage resistance and low-temperature crack resistance. The purpose of this paper is to serve as a valuable reference for investigating the mechanism of modified asphalt foaming and to enhance the efficiency of cold recycled pavement regeneration processes.

Split crRNA-motivated amplification-free RNA testing with CRISPR–Cas12a

Split crRNA-motivated amplification-free RNA testing with CRISPR–Cas12a

Comparative analysis of lumped and semi-distributed hydrological models in humid Mediterranean environments

ABSTRACT This study conducts a comparative analysis of four hydrological models—GR4J, HBV-light, HEC-HMS, and WEAP—to evaluate their effectiveness in simulating surface water responses in humid Mediterranean climates. The Longaví basin, located in the Maule River basin of central Chile, was selected for its characteristic climate. The models used lumped and semi-distributed approaches to simulate the basin’s hydrological cycle. The study area was divided into three zones, considering climate, soil properties, and altitude. Results showed that GR4J, HEC-HMS, and WEAP performed well during the winter months (June to October), while HBV-light was more effective in summer (November to May). WEAP model, with its extensive parameterization, effectively captured streamflow variability during the rainy season. The Differential Split Sample Test indicated that GR4J and WEAP offered the best fit for analysing climatic variability. These models are highly recommended for climate change impact studies, given their strong performance in capturing seasonal hydrologic responses across similar regions.

Study on the Compressive and Tensile Properties of Latex-Modified Cement Stone.

The integrity of wellbores is essential for the safe and efficient operation of drilling activities. Cement plays a critical role in this process, serving as a primary barrier that isolates the casing from the surrounding formation. To ensure the proper application of cement in wells, a thorough understanding of its mechanical properties is essential. Latex-modified cement stone (LMCS) offers significant advantages due to its anti-channeling, anti-corrosion, and mechanical characteristics. This study examined the mechanical properties of LMCS through uniaxial and triaxial compression and Brazilian splitting tests. Under uniaxial compression, the elastic modulus, Poisson's ratio, and compressive strength of LMCS were found to range from 4.08 to 8.29 GPa, 0.05 to 0.46, and 15.82 to 22.21 MPa, respectively. In triaxial compression tests with confining pressures of 2 MPa, 4 MPa, 6 MPa, 8 MPa, and 10 MPa, the elastic modulus ranged from 4.48 to 6.87 GPa, Poisson's ratio from 0.05 to 0.16, and compressive strength from 27.38 to 39.58 MPa. The tensile strength of LMCS ranged from 2.34 to 3.72 MPa. Moreover, the compressive strength of LMCS increased with confining pressure, showing enhanced resistance to failure due to the confining effect. However, the rate of increase gradually diminished. Strength criteria for LMCS, including Mohr-Coulomb and Drucker-Prager parameters, were derived from the triaxial compression tests. These strength criteria parameters provide a useful reference for developing the constitutive model of LMCS and for simulating triaxial compression conditions. The findings of this research offer valuable insights that can guide the construction of oil and gas wells.

Rational phosphorization of ferrocene-based metal organic framework for enhanced oxygen evolution and urea oxidation performance

Developing high-performance and inexpensive water-splitting electrocatalysts is crucial for addressing current energy and environmental issues. In this work, a ferrocene (Fc)-based metal organic framework (MOF) was rationally phosphorized to construct a CoFeP/MOF composite electrocatalyst. Thanks to the excellent conductivity, high specific surface area, and rich heterojunction interfaces, the prepared catalyst exhibits outstanding catalytic activity and long-term endurance, which can realize 50 mA cm−2 at an overpotential of 246 mV for oxygen evolution reaction (OER) in 1.0 M KOH and a cell potential of 1.441 V (vs. RHE) for urea oxidation reaction (UOR) in 1.0 M KOH and 0.5 M urea. The electrolyzer assembled from the prepared electrode and Pt/C electrode can drive 50 mA cm−2 at 1.605 V and 1.524 V (vs. RHE) in the overall/urea-assisted water splitting tests, demonstrating great application prospects. This work provides valuable reference for improving the performance of MOF type bifunctional water electrolysis catalysts.

A-268 Comparison of the Elecsys® HCV Duo Assay to Standard of Care Algorithmic Testing

Abstract Background Traditional hepatitis C virus (HCV) testing methods, though effective, may miss crucial diagnostic opportunities. The goal of this study was to assess the utility of Elecsys® HCV Duo antibody/antigen (Ab/Ag) assay as an alternative to traditional HCV algorithmic testing in the United States. Methods A prospective study was conducted at Barnes Jewish Hospital in St. Louis, Missouri. Patients with concurrent HCV Ab and molecular testing ordered within 48 h were enrolled. A total of 1,351 remnant serum and plasma-EDTA specimens were frozen following standard of care testing, which consisted of the Abbott Architect anti-HCV assay with reflex to cobas® HCV molecular assay. Patient demographics, risk factors, and results from both standard of care and HCV Duo testing were recorded. Results Among 1351 specimens, the HCV positivity rate as defined by algorithm was 19.9% (269/1351). Risk factors including homelessness and prior intravenous drug use were significantly associated with HCV diagnosis (P<0.0001). HCV Duo testing demonstrated a positivity rate of 19.6% (263/1345) based on Ab/Ag dual positivity. Comparing the HCV Duo Ab module to standard of care serology revealed a 95.1% PPA (95% CI, 93.1-96.5) and 98.8% NPA (95% CI, 97.7-99.4), while the HCV Duo Ag component exhibited a 72.3% PPA (95% CI, 66.7-77.3) and 99.6% NPA (95% CI, 99.1-99.9) when compared to molecular testing. In HCV-RNA+ patients, the Ag component was positively correlated to viral load with a Spearman r of 0.770 (95% CI, 0.715-0.815). The median viral load with for patients with Ag+ results was 6.27 log10 IU/mL (IQR, 5.90-6.69) and for patients with Ag- results was 5.08 log10 IU/mL (IQR, 4.47-5.61). Of HCV-RNA+ specimens , 266/271 (98.2%) were successfully detected on the Ab module. Among anti-HCV+/HCV-RNA+ cases, 99.2% (261/263) were detected as Ab+/Ag+ on the HCV Duo assay. These had a turnaround time (TAT) from serology to molecular results of 28.1 ± 23.5 h, which may have been significantly decreased if Ab/Ag dual positivity was solely used to establish a diagnosis (average TAT of 27 min). The remaining two discrepant specimens were from patients with a prior history of HCV infection, which may represent false negatives or seronegative chronic HCV infections. Notably, 5/8 (62.5%) anti-HCV-/HCV-RNA+ specimens were detected on the HCV Duo assay, which would have been missed by traditional algorithmic testing. These five patients had viral loads ranging from 323-41,400,000 IU/mL, compared to <15-5,400 IU/mL in the three undetected specimens. Of these five additional patient specimens captured on HCV Duo, two patients received an organ from an HCV+ donor, while the remaining three had no known history of HCV infection or transplant from an HCV+ donor. Conclusions The Elecsys® HCV Duo Ab/Ag assay, with its high sensitivity and specificity, drastically shortens the diagnostic window. Importantly, it successfully identified several anti-HCV-/HCV-RNA+ cases, a subgroup often undiagnosed by current algorithmic testing, demonstrating promise for improved diagnostic efficiency and accuracy in HCV detection. Further investigation is needed to determine whether improved diagnostic efficiency is due to enhanced antibody or antigen detection.