bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring synergistic solid lubrication for enhanced tribological performance in biochar-reinforced aluminum matrix composites fabricated by induction sintering
Authors: Abdo Hany S. , Samad Ubair Abdus , Alnaser Ibrahim A. , Ragab Sameh A. , Fouly Ahmed
Published: October 2024

This study presents a pioneering methodology for the synthesis of aluminum matrix composites (AMCs) fortified with biochar, sourced from renewable biomass feedstocks. Employing a systematic approach, various biochar weight percentages were meticulously investigated to discern their impact on the mechanical and tribological properties of the resulting composites. Through a comprehensive battery of tests, encompassing evaluations of compressive strength and hardness, the study elucidated significant enhancements in mechanical robustness consequent to biochar integration. Notably, the mixture formulation with 7.5 wt. % biochar emerged as the optimal configuration, showcasing an impressive 8.83% augmentation in compressive strength and a notable 15% elevation in the hardness relative to the pristine aluminum pure matrix. The research extends beyond traditional analyses, introducing an exploration of tribological performance. The incorporation of biochar is anticipated to impart solid lubricating properties, influencing wear and friction characteristics. Future research directions may delve into the nuanced interplay between biochar content and tribological enhancements, offering insights into the tailored manipulation of mechanical and tribological properties in AMC through biochar reinforcement. The examination of wear and friction exhibited that the friction coefficient decreased by 6.4% when 10 wt. % of biochar was added. Furthermore, the wear resistance improved proportionally with the biochar weight percentage, regardless of the normal loads applied. The finite element model further demonstrated an enhancement in load-carrying capacity due to biochar incorporation. Finally, analysis of the texture of the rubbed surface presented that the inclusion of biochar in an AL matrix changed the way wear occurs and decreased the amount of weight lost during friction. The resulting materials not only exhibit improved mechanical strength but also hold promise for applications in industries that demand robust, environmentally conscious solutions with enhanced tribological performance.
Numerical tank for suspended sediment transport under strong nonlinear waves in shallow water zones
Authors: Jiang Yuanjun , Zhang Jianpeng , Chen Xin , Zhou You
Published: October 2024

Wave nonlinearity and free surface effects are recognized as important factors for sediment transport under nonlinear waves. Existing studies primarily focus on oscillatory water tunnel (OWT) instead of real waves for sediment transport due to the challenges in constructing real-scale wave tank. In contrast to OWT, the wave tank performs both wave nonlinearity and free surface effect on sediment transport. A numerical wave-sediment tank is developed for strong nonlinear wave propagation over sediment bed with low computational cost. The nonlinear wave is generated by defining the inlet boundary condition and absorbed by using a damping function, and the classical volume of fluid method is used to handle the free surface. The numerical tank further considers particle wake vortex effect and modifications in relative velocity of high sediment concentration, and incorporates phase lag, mass conservation, acceleration effect, and asymmetric wave boundary layer into near-bed sediment conditions. Therefore, the numerical tank avoids complex calculations for near-bed hyper-concentrated sediment in comparison with a two-phase model, i.e., the calculation of particle collision, friction, and detection of mobile bed surface. The numerical tank reasonably agrees with large-scale wave flume experiments and a two-phase model including free surface wave, and successfully performs sediment transport induced by strong nonlinear (second-order Cnoidal) wave. Compared to the OWT, the extra onshore streaming caused by free surface wave significantly enhances onshore sediment transport.
The smallest electrochemical bubbles
Authors: Gadea Esteban D. , Perez Sirkin Yamila A. , Molinero Valeria , Scherlis Damian A.
Published: October 2024

Many of the relevant electrochemical processes in the context of catalysis or energy conversion and storage, entail the production of gases. This often implicates the nucleation of bubbles at the interface, with the concomitant blockage of the electroactive area leading to overpotentials and Ohmic drop. Nanoelectrodes have been envisioned as assets to revert this effect, by inhibiting bubble formation. Experiments show, however, that nanobubbles nucleate and attach to nanoscale electrodes, imposing a limit to the current, which turns out to be independent of size and applied potential in a wide range from 3 nm to tenths of microns. Here we investigate the potential-current response for disk electrodes of diameters down to a single-atom, employing molecular simulations including electrochemical generation of gas. Our analysis reveals that nanoelectrodes of 1 nm can offer twice as much current as that delivered by electrodes with areas four orders of magnitude larger at the same bias. This boost in the extracted current is a consequence of the destabilization of the gas phase. The grand potential of surface nanobubbles shows they can not reach a thermodynamically stable state on supports below 2 nm. As a result, the electroactive area becomes accessible to the solution and the current turns out to be sensitive to the electrode radius. In this way, our simulations establish that there is an optimal size for the nanoelectrodes, in between the single-atom and ∼3 nm, that optimizes the gas production.
The highly invasive water hyacinth (
Eichhornia crassipes
[Mart.] Solms) and its control methods in Ethiopia’s freshwater ecosystems
Authors: Addis Awoke Damtie , Desta Takele Taye
Published: October 2024

Water hyacinth,
Eichhornia crassipes
, is an obtrusive aquatic vascular plant native to South America (Neotropics). It is among the notorious and invasive weeds that adversely affect the tropical and subtropical world. In Ethiopia,
E
.
crassipes
was first reported in 1956 on Lake Koka and a flooded waterway of Awash River. It was introduced to Ethiopia as an ornamental plant to spruce up its freshwater ecosystems. It is a perennial aquatic plant that forms monotypic mats (thick layers), can float freely, or is anchored in shallow water, and can grow up to 1 m when it forms dense mats. This invasive weed has spread across continents, countries, and freshwater environments mainly by humans, birds, rivers, and watersheds. But humans are the main agents for the spread of water hyacinths. Water hyacinth has both direct and indirect adverse impacts on freshwaters, wetlands, the production of fish, crops, livestock, electric power, irrigation, tourism, and public health.
E
.
crassipes
fast growth, rapid asexual propagation especially using stolons, a wide range of freshwater ecosystem adaptations, and complex root system made the control effort a demanding task. However, manual removal of water hyacinths at an early stage of growth and while they spread over a small area could be possible. Arthropods such as
Neochetina brunchi
and
Neochetina eichhorniae
, and parasitic fungi like
Alternaria alternata
,
Alternaria sp
,
Alternaria tenuissima
, and
Neofusicoccum parvum
have been used as biological control agents (at a trial level) in Ethiopia. When there is high infestation, chemical control methods including acetic acid, 2, 4-D dimethyl amine, and glyphosate can be cautiously used. Although laborious mechanical and manual control methods can be used to remove water hyacinths. An efficient control method that is cheap, safe, and relatively eco-friendly is the integrated use of biological and mechanical control methods. An all-inclusive effort is required to control the invasion of water hyacinth.
Corner and edge states in topological Sierpinski Carpet systems
Authors: Lage L L , Rappe N C , Latgé A
Published: October 2024

Fractal lattices, with their self-similar and intricate structures, offer potential platforms for engineering physical properties on the nanoscale and also for realizing and manipulating high order topological insulator states in novel ways. Here we present a theoretical study on localized corner and edge states, emerging from topological phases in Sierpinski Carpet (SC) within a π-flux regime. A topological phase diagram is presented correlating the quadrupole moment with different hopping parameters. Particular localized states are identified following spatial signatures in distinct fractal generations. The specific geometry and scaling properties of the fractal systems can guide the supported topological states types and their associated functionalities. A conductive device is proposed by coupling identical SC units providing transport response through projected edge states which carry on the details of the system’s topology. Our findings suggest that fractal lattices may also work as alternative routes to tune energy channels in different devices.
Investigating the exciton dynamics in InGaN/GaN core-shell nanorods using time-resolved cathodoluminescence
Authors: Loeto K , Kusch G , Brandt O , Coulon P-M , Hammersley S , Lähnemann J , Girgel I , Fairclough S M , Sarkar M , Shields P A , Oliver R A
Published: October 2024

This study examines the exciton dynamics in InGaN/GaN core–shell nanorods using time-resolved cathodoluminescence (TRCL), which provides nanometer-scale lateral spatial and tens of picoseconds temporal resolutions. The focus is on thick (>20 nm) InGaN layers on the non-polar, semi-polar and polar InGaN facets, which are accessible for study due to the unique nanorod geometry. Spectrally integrated TRCL decay transients reveal distinct recombination behaviours across these facets, indicating varied exciton lifetimes. By extracting fast and slow lifetime components and observing their temperature trends along with those of the integrated and peak intensity, the differences in behaviour were linked to variations in point defect density and the degree and density of localisation centres in the different regions. Further analysis shows that the non-polar and polar regions demonstrate increasing lifetimes with decreasing emission energy, attributed to an increase in the depth of localisation. This investigation provides insights into the intricate exciton dynamics in InGaN/GaN nanorods, offering valuable information for the design and development of optoelectronic devices.
Error-rejecting entanglement purification and concentration for one-dimensional waveguide-emitter system
Authors: Du Fang-Fang , Li Ling-Hui , Ren Xue-Mei , Wang Yang-Yang , Liu Wen-Yao
Published: October 2024

The distribution of maximal entanglement stands as a pivotal technique in long-distance practical quantum communication. Specifically, achieving high-fidelity entanglement distribution leans upon efficacious entanglement purification and entanglement concentration. In this paper, we materialize error-rejecting nonlocal entanglement purification protocol (EPP) and entanglement concentration protocol (ECP) for solid-state emitter systems assisted by the scattering property of photon-emitter in one-dimensional waveguide. The parity-check gates of both the EPP and ECP can herald the faulty events with the help of the detectors that click, so they are accomplished, in principle, with unity fidelities, which are conducive to implement two protocols. Moreover, additional emitters are unnecessary except a single photon.
The exchange interaction between neighboring quantum dots: physics and applications in quantum information processing
Authors: Zhou Zheng , Li Yixin , Wu Zhiyuan , Ma Xinping , Fan Shichang , Huang Shaoyun
Published: October 2024

Electron spins confined in semiconductor quantum dots (QDs) are one of potential candidates for physical implementation of scalable quantum information processing technologies. Tunnel coupling based inter exchange interaction between QDs is crucial in achieving single-qubit manipulation, two-qubit gate, quantum communication and quantum simulation. This review first provides a theoretical perspective that surveys a general framework, including the Helter−London approach, the Hund−Mulliken approach, and the Hubbard model, to describe the inter exchange interactions between semiconductor quantum dots. An electrical method to control the inter exchange interaction in a realistic device is proposed as well. Then the significant achievements of inter exchange interaction in manipulating single qubits, achieving two-qubit gates, performing quantum communication and quantum simulation are reviewed. The last part is a summary of this review.
Design and test of a module of a breathable Electrostatic Shield for the MITICA 1 MV negative ion Beam Source
Authors: Chitarin G. , Patton T. , Pilan N. , Sartori E.
Published: October 2024

The electrical insulation of the MITICA Beam Source at 1 MV is a challenging issue, which has not been fully addressed so far on the basis of experimental results and of theoretical models available in literature. Being MITICA the full-size prototype of the Heating Neutral Beam Injector for the ITER fusion experiment, its electrical insulation is constituted just by vacuum gaps and alumina insulators, since other insulating materials such as SF6 gas or fibreglass-reinforced plastic (FRP) would be quickly degraded by the expected neutron flux produced by fusion reaction. Extrapolations based on HV tests on reduced-scale models have recently indicated the risk of electrical breakdowns in the vacuum gap between electrodes nominally operating at -1 MV and the vacuum vessel (at ground potential). The risk of electrical breakdown can be mitigated by introducing an intermediate Electrostatic Shield (ES), which essentially is an equipotential (metallic) enclosure surrounding the HV electrode, so as to divide the vacuum gap in two independent insulating gaps of 400 kV and 600 kV respectively. However, for optimal negative ion production, the ion source shall operate in H2 or D2 at a pressure of ∼ 0.3 Pa and unavoidably produces a flow of gas leaking out in the surrounding vacuum. Thus, the presence of an intermediate shield can substantially increase the background gas pressure in the vacuum gaps, and, due to the large gap length (0.6 m), exacerbate the risk of breakdown when the pressure approaches the conditions of Paschen-type discharges. In addition to this, RF-induced breakdowns were found on the rear side of the ion source during the operation of the prototype source SPIDER, which were somewhat correlated to a relatively high hydrogen pressure in that area. For these reasons, a structure capable of constituting a full equipotential barrier all around the BS and, at the same time, having sufficient gas conductivity (breathability) to allow efficient pumping of background gas, has been designed. In the first part of the paper, the requirements and design optimization of a breathable module of the intermediate ES are described. Then, an experimental campaign for the validation of the electrode implementation the test configurations and the experimental procedure is discussed.
Radiocarbon as a tracer of the fossil fraction of regional carbon monoxide emissions
Authors: Blyth Liam , Graven Heather , Manning Alistair J , Levy Peter
Published: October 2024

Carbon monoxide (CO) is an atmospheric pollutant with a positive net warming effect on the climate. The magnitude of CO sources and the fraction of fossil vs biogenic sources are still uncertain and vary across emissions inventories. Measurements of radiocarbon (14C) in CO could potentially be used to investigate the sources of CO on a regional scale because fossil sources lack 14C and reduce the 14C/C ratio (Δ14C) of atmospheric CO more than biogenic sources. We use regional Lagrangian model simulations to investigate the utility of Δ14CO measurements for estimating the fossil fraction of CO emissions and evaluating bottom-up emissions estimates (United Kingdom Greenhouse Gas, UKGHG, and TNO Copernicus Atmosphere Monitoring Service, TNO) in London, UK. Due to the high Δ14CO in atmospheric CO from cosmogenic production, both fossil and biogenic CO emissions cause large reductions in Δ14CO regionally, with larger reductions for fossil than biogenic CO per ppb added. There is a strong seasonal variation in Δ14CO in background air and in the sensitivity of Δ14CO to fossil and biogenic emissions of CO. In the UK, the CO emissions estimate from TNO has a higher fraction from fossil fuels than UKGHG (72% vs 67%). This results in larger simulated decreases in Δ14C per ppb CO for TNO emissions. The simulated differences between UKGHG and TNO are likely to be easily detectable by current measurement precision, suggesting that Δ14CO measurements could be an effective tool to understand regional CO sources and assess bottom-up emissions estimates.
Fermion integrals for finite spectral triples
Authors: Barrett John W
Published: October 2024

Fermion functional integrals are calculated for the Dirac operator of a finite real spectral triple. Complex, real and chiral functional integrals are considered for each KO-dimension where they are non-trivial, and phase ambiguities in the definition are noted.
On the ground state of one-dimensional quantum droplets for large chemical potentials
Authors: Holmer J , Zhang K Z , Kevrekidis P G
Published: October 2024

In the present work we revisit the problem of the quantum droplet in atomic Bose–Einstein condensates with an eye towards describing its ground state in the large density, so-called Thomas–Fermi (TF) limit. We consider the problem as being separable into 3 distinct regions: an inner one, where the TF approximation is valid, a sharp transition region where the density abruptly drops towards the (vanishing) background value and an outer region which asymptotes to the background value. We analyze the spatial extent of each of these regions, and develop a systematic effective description of the rapid intermediate transition region. Accordingly, we derive a uniformly valid description of the ground state that is found to accurately match our numerical computations. As an additional application of our considerations, we show that this formulation allows for an analytical approximation of excited states such as the (trapped) dark soliton in the large density limit.
Numerical assessment of thermal bridging effects in 3D-printed foam concrete walls
Authors: Chamatete Kunda , Yalçınkaya Çağlar
Published: October 2024

Integrating smart technology and advanced materials in the construction industry has revolutionized traditional building practices, enhancing efficiency, sustainability, and overall performance. Researchers and professionals in the construction sector have shown significant interest in three-dimensional concrete printing (3DCP) for automating structural engineering tasks. Despite its potential as a sustainable solution to modern construction issues, there is a lack of research on the thermal insulation performance of three-dimensional printed concrete (3DPC) building envelopes, and the potential for integrating foam concrete (FC) to enhance energy efficiency has not yet been studied. This paper presents a numerical analysis examining how different infill geometries affect the thermal performance of 3D-printed foam concrete (3DPFC) lattice envelopes. Six lattice structures were designed with identical thickness, height, length, and comparable insulation areas. The effects of the contact (intersection) area of webs with the interior face shell, webs, and infill rows on the thermal performance of granularly insulated envelopes were studied. The effectiveness of insulation was also established. The findings indicate that the thermal transmittance of 3DPC envelopes correlates directly with the contact area of the webs and the interior surface, with U-values ranging from 0.151 W m2·K to 0.652 W/m2·K. Notably, the absence of direct connections between exterior and interior surfaces enhances insulation efficiency, with double-row structures achieving up to 94% insulation efficiency. However, when there is a direct connection between the two surfaces, the thermal performance of these envelopes is mainly affected by the contact (intersection) area of the webs with the interior face rather than the number of webs. By integrating foam concrete and double-row walls, this study demonstrates an innovative approach to reducing thermal bridging and improving energy performance in 3D-printed construction. The results offer novel insight into optimizing the thermal behavior of 3DPC systems for sustainable building practices.
Stretchable printed circuit boards using a silicone substrate of variable stiffness and conventional PCB fabrication methods
Authors: Jamali Armin , Lehmann Christoph , Aditya Ravi Teja , Goldschmidtboeing Frank , Woias Peter , Comella Laura M
Published: October 2024

Stretchable printed circuit boards (S-PCBs) offer unique advantages over rigid PCBs such as enabling conformability to changing environments and ergonomic designs with increased lifetime under dynamic loads. This study introduces an innovative fabrication method and a cost-effective solution for rapid prototyping S-PCBs using commercially available materials. By utilizing silicone substrates with different levels of stiffness and structured copper sheets for electrical connections, the S-PCBs feature ‘stiff islands’ embedded in a flexible base material. This fabrication method helps alleviate mechanical strain on strain-sensitive components while allowing local deformation of the S-PCB. The proposed fabrication method does therefore enable to integrate surface mount device components into S-PCBs and facilitates complex circuit designs while maintaining stretchability and fatigue resistance. Through material characterization, video strain analysis, as well as quasi-static and cyclic loading tests, this article demonstrates the efficacy of our approach. Based on the experimental results, we provide insights into failure modes and suggest design principles to further enhance the durability of S-PCBs fabricated with our method. We then conclude by presenting a soft wearable S-PCB demonstrator. The S-PCBs fabricated with this method withstood mechanical strains up to 100% and cyclic loads with 30% strain up to 625 cycles. The results are very promising for applications in soft robotics, wearable devices, and soft sensors and actuators. Overall, our study offers a comprehensive toolkit for fast S-PCB prototyping, paving the way for advancements in stretchable electronics with a high degree of complexity and stretchability.
MVSF-AB: Accurate antibody-antigen binding affinity prediction via multi-view sequence feature learning
Authors: Li Minghui , Shi Yao , Hu Shengqing , Hu Shengshan , Guo Peijin , Wan Wei , Zhang Leo Yu , Pan Shirui , Li Jizhou , Sun Lichao , Lan Xiaoli
Published: October 2024

Motivation

Predicting the binding affinity between antigens and antibodies accurately is crucial for assessing therapeutic antibody effectiveness and enhancing antibody engineering and vaccine design. Traditional machine learning methods have been widely used for this purpose, relying on interfacial amino acids’ structural information. Nevertheless, due to technological limitations and high costs of acquiring structural data, the structures of most antigens and antibodies are unknown, and sequence-based methods have gained attention. Existing sequence-based approaches designed for protein-protein affinity prediction exhibit a significant drop in performance when applied directly to antibody-antigen affinity prediction due to imbalanced training data and lacking design in the model framework specifically for antibody-antigen, hindering the learning of key features of antibodies and antigens. Therefore, we propose MVSF-AB, a Multi-View Sequence Feature learning for accurate Antibody-antigen Binding affinity prediction.

Results

MVSF-AB designs a multi-view method that fuses semantic features and residue features to fully utilize the sequence information of antibody-antigen and predicts the binding affinity. Experimental results demonstrate that MVSF-AB outperforms existing approaches in predicting unobserved natural antibody-antigen affinity and maintains its effectiveness when faced with mutant strains of antibodies.

Availability and implementation

Datasets we used and source code are available on our public GitHub repository https://github.com/TAI-Medical-Lab/MVSF-AB.
Investigating interferon type I responses in patients with suspected giant cell arteritis and polymyalgia rheumatica
Authors: van Nieuwland Marieke , Mulder A H Leontine , Colin Edgar M , Alves Celina , van Bon Lenny , Brouwer Elisabeth
Published: October 2024

Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are closely related inflammatory disorders. Easily measurable biomarkers defining active disease and identifying patients in need of glucocorticoid sparing treatment options are highly desired. Interferon Type I (IFN-I) might be involved in disease pathology; however, evidence is limited. This study explores a systemic IFN-I signature and expression of IFN-I markers in GCA and PMR patients. Treatment naive GCA and PMR patients, and PMR patients with glucocorticoid treatment were included. Patients suspected of but not diagnosed with GCA were used as controls. Five relevant IFN-I-stimulated genes were identified in literature, and relative expression levels were determined using quantitative reverse transcription polymerase chain reaction (RT-qPCR) in peripheral blood mononuclear cells. An IFN-I score was generated. Serum levels of IFN-I induced C-X-C motif chemokine 10 (CXCL10) and Galectin-9 were determined by multiplex immunoassay. There were no differences in IFN-I scores between the groups. An IFN-I signature was observed in 0/9 controls, 2/11 GCA patients, 4/20 treatment naive PMR patients, and 2/10 PMR patients with treatment. Serum CXCL10 and Galectin-9 were not increased in GCA or PMR patients compared to control patients. Treated PMR patients had lower CXCL10 levels [423.2 pg/ml (375.1–491.1)] compared to treatment naive PMR patients [641.8 pg/ml (552.8–830.6)]. An IFN-I signature does not distinguish GCA and PMR patients from controls. Also, IFN-I-induced serum markers are not upregulated in GCA and PMR patients. Easily measurable IFN-I-induced serum markers will therefore probably not aid in diagnosis and additional treatment options in newly diagnosed GCA and PMR patients.
A-003 Beckman Coulter DxI 9000 Immunoassay Analyzer’s High Sensitivity Troponin I achieves >90% six sigma performance when assessed against clia 2024 performance goals
Authors: Westgard S
Published: October 2024

Background

In July 2024, the Clinical Laboratory Improvement Act (CLIA) proficiency testing (PT) criteria will directly regulate Troponin I performance for the very first time. The new CLIA goal is 0.9 ng/mL or 30%, whichever is greater. CAP previously set a goal of 30% or 3 times the group standard deviation (SD), whichever is greater, a more permissive setting. Estimates of current instrument group performance from an international proficiency testing (PT) survey have shown none of the 5 major diagnostic instruments can achieve the biological minimum goal at a 6-Sigma level, while 4 of the 5 instruments perform at 3 Sigma or below. Performance of these platforms was assessed using the methodology introduced in 2006 by Westgard JO and Westgard SA. The DxI 9000 high sensitivity Troponin I assay was assessed to determine if it could achieve the new CLIA 2024 goals.

Methods

The DxI 9000 high sensitivity Troponin I assay was assessed with three reagent lots, on both serum and Lithium Heparin (LiHep) samples, following Clinical Laboratory Standards Institute (CLSI) protocols EP05 and EP09 to estimate imprecision and bias. The new CLIA 2024 PT criteria supplied the allowable total error for the standard Sigma-metric calculation: Sigma-metric = (TEa - |bias|) / SD The Sigma-metric predicts not only future problems with PT, but also potential optimization of QC procedures, including fewer Westgard Rules, control levels, even reduced QC frequency which can lead to less cost, time, and materials.

Results

The majority (91.7%) of data points across the analytical measuring range for DxI 9000’s high sensitivity Troponin I assay from both serum and LiHep samples achieved 6-Sigma performance. For serum, only 8.3% of samples achieved 5-sigma performance. For LiHep, only 4.2% of the performance was 4 Sigma. None of the performance was 3 Sigma or lower.

Conclusions

The superior precision observed on DxI 9000 high sensitivity Troponin I delivers overwhelming 6-sigma performance when assessed by CLIA’s 2024 goal. This assay is highly unlikely to face PT difficulties and can be optimized for reduced Westgard Rules, reduced control levels leading to a reduction in time, materials, and cost.
A-008 Verification of Interchangeability of Results for High-Sensitivity Troponin (TNIH) Between Atellica Solution® and Atellica CI® Analyzers
Authors: Ruiz-Alvarez M , Lapeña-Garcia S , Garcia-Valdecasas S , Costales-Lucia T , Moreno-Romero A , Sanchez-Fuertes J , Barrionuevo-Gonzalez M
Published: October 2024

Background

Method intercomparison is an essential requirement that must be carried out in Clinical Laboratories before changing a method or instrument to verify the interchangeability of results. High-sensitivity troponin (TNIH) is an extraordinarily sensitive marker for detecting myocardial damage. Currently, it is determined in Atellica Solution® autoanalyzers (Siemens Healthineers) in our laboratory. After validating a new Siemens device, the Atellica CI®, it is essential to ensure the interchangeability of results in our laboratory accredited by ISO 15189: 2012.

Objectives

Our objective is to verify if the TNIH method in serum is interchangeable between the analyzers: Atellica Solution® and CI®.

Methods

A total of 77 serum samples from patients with TNIH values ranging from 2.5 to 25000 ng/L were processed by both analyzers. The statistical analysis of the results was performed using Passing-Bablok regression and Bland-Altman analysis, along with the Pearson correlation coefficient as a criterion to verify the adequacy of the sample size. Results are expressed with a 95% confidence interval. The statistical intercomparison study was conducted using Method Validator Version 1.19

Results

In statistical analysis of Bland-Altman, no statistically significant differences were observed between the results obtained on both Atellica Solution® and CI 1900® analyzers since the 95% CI of the mean difference obtained includes the null value.Passing-Bablok regression shows a statistically significant, nearly negligible proportional systematic error, as the lower limit of the 95% CI is very close to 1; and a constant systematic error since the 95% CI of the intercept does not include the value 0

Conclusions

Considering the 99th percentile established in our laboratory as a clinical decision value obtained after our own study of 45 ng/L, we do not exceed our quality specification for TNIH based on biological variability, which is 19.4%. Therefore, we can conclude that the determination of TNIH between both analyzers is interchangeable.
A-075 Comparability of Free Testosterone Measurements- Results of the Interlaboratory Study
Authors: Danilenko U , Zhou H , Sugahara O , Vesper H W
Published: October 2024

Background

Assessment of free testosterone (FT) has been recommended as a biomarker for diagnosis and management of hypogonadism and female hyperandrogenism. Reliable laboratory measurements are essential for correctly diagnosing and treating these diseases. FT is currently measured using direct commercial immunoassays, assays employing equilibrium dialysis (ED) or other separation techniques, or it is estimated by calculating free testosterone (cFT). There are concerns about the accuracy and reliability of current methods that may impact patient care. To obtain more information about variability of FT measurements used in patient care, CDC’s Clinical Standardization Programs (CDC CSP) conducted an interlaboratory comparison study.

Methods

CDC CSP developed an accurate, automated method using ED coupled with isotope dilution ultra-high-performance liquid chromatography tandem mass spectrometry (ED-UHPLC-MS/MS). The ED step follows an internationally recognized procedure. The method is calibrated with primary reference material (National Measurement Institute-M914) and was used to assign target values to sera used in the study. The FT concentrations ranged from 3 to 339 pg/mL. In the interlaboratory comparison study single-donor serum samples were provided to participants operating FT methods used in patient care. The participating methods included commercially available platforms utilizing Chemiluminescence Immunoassay or radioimmunoassay techniques, as well as laboratory-developed assays using ED-LC-MS/MS.

Results

Preliminary findings of the CSP interlaboratory comparison study found large variability among participating assays. The agreement among IA and among ED-LC-MS/MS assays was close. However, FT concentrations obtained by IAs were in average 6 times lower compared to the ED-LC-MS/MS methods. Results estimated using the Vermeulen equation overestimated FT in average by 15% compared to the ED-LC-MS/MS methods and by over 6 times compared to IAs.

Conclusions

Large variability is observed between FT laboratory developed tests (LDTs) and IAs. As both LDTs and IAs are used in patient care, standardization of FT measurements to assure better patient care is needed. CDC CSP is addressing the need by developing highly accurate and precise FT method and conducting an interlaboratory comparison studies that can aid with improvement of the agreement among assays and identifying potential factors causing differences among assays.
A-089 Development and Implementation of an online learning Environment for clinical chemistry resident education: UAMS experience
Authors: Hagrass H A
Published: October 2024

Background

The clinical chemistry resident teaching rotation extends over 12 weeks, equivalent to a three-month period. The first chemistry rotation is scheduled for the first year, the second for the second year, and the final rotation for the fourth year. Throughout the 12-week teaching rotation, residents are exposed to a range of clinical chemistry concepts, including laboratory management, quality assurance, and test interpretation, among others. By the end of the program, residents should be well-equipped to provide expert guidance and advice on clinical chemistry matters. The current generation of learners values education that is flexible and accessible, leading to the growth and integration of blended or hybrid learning in various educational settings. This research aims to assess the effectiveness of the newly implemented online platform by analyzing feedback from residents and their quiz scores before and after the change.

Methods

A Box folder was created for the clinical chemistry rotation and divided into three subfolders for each rotation. Each subfolder contains materials for quizzes, cases for discussions, articles, and presentations. All the residents have access to the Box folder for educational materials. Previously, reading assignments were emailed the day before sessions, while quizzes and cases were given during sessions. In order to assess the efficacy of the online platform, we conducted an analysis of the average quiz scores before and after its implementation. In addition, we utilized the feedback provided by residents to evaluate the platform's practicality and adaptability.

Results

On average, the residents post-implementation scores (30 quizzes) increased by 20% (10%-35%). The pre-implementation average score was 50%, which increased to an 80% success rate after implementation. The residents unanimously agreed that the new online learning environment was very helpful in preparing them for the in-person session. They also expressed dissatisfaction with the previous learning style, which made it difficult for them to focus on learning while answering questions given on the spot. Instead, they preferred being provided with the questions beforehand, which allowed them to carefully read and search for answers to quizzes and case studies. The residents found that speed-reading through the questions and quickly glancing over the answers and explanations was not helpful to their learning process. Overall, the new learning format was able to alleviate their stress levels and helped them better prepare for the in-person session.

Conclusions

The online learning environment has been found to be a preferred mode of education by UAMS pathology residents. It has been deemed effective and suitable for our academic setting.
A-097 Body Fluid Validation for 11 Analytes on a Chemistry Analyzer
Authors: Boyert N , McShane A J
Published: October 2024

Background

Most clinical chemistry assays are intended for use in serum, plasma, urine, and/or CSF with no performance characteristics on body fluids. However, testing of body fluids can be medically necessary for certain diagnoses. Such as determining the cause of fluid buildup in peritoneal spaces, pleural effusions, whether effusions are transudates or exudates, and even diagnosing some joint disorders. To provide these medically necessary tests, the burden is on the laboratory to perform regulatory-required validations. Herein is the validation of 11 clinical chemistry analytes in several common body fluids.

Methods

Mixing and stability studies were performed for the following analytes on the Roche cobas c702 (Roche Diagnostics), using the methods intended for use with serum/plasma samples: Albumin, Amylase, Bilirubin, Urea Nitrogen, Cholesterol, Creatinine, Glucose, Lactate Dehydrogenase, Lipase, Protein, and Triglycerides. Six individual fluid samples were mixed with the intended use matrix in 3 ratios: 1:3, 1:1, and 3:1. The following matrices were evaluated: pleural, peritoneal, JP drainage, synovial, and pancreatic cyst fluids. Stabilities were tested for 7 days at room temperature (RT) and 2-8°C. A maximum dilution study was also performed for Amylase.

Results

Mixing Study: The results are shown in the table below:

Stability: For most body fluids, analytes were stable for 7 days at RT and 2-8 °C. The following analytes displayed shorter stability at RT: Bilirubin (peritoneal: 2 days, pleural: 1 day, JP drainage: 1 day), Urea Nitrogen (JP drain fluid: 2 days), Lipase (peritoneal fluid 5 days), and Triglycerides (peritoneal fluid: 5 days). Lactate dehydrogenase in pleural fluid showed a stability of 5 days at RT and 2 days at 2-8 °C. Maximum Dilution A 1:505 compounded manual and automated dilution displayed a <7% bias.

Conclusions

No sample matrix interferences were observed for any of the body fluids-analyte pairs tested allowing for this medically necessary testing.
A-109 The impact of adjusting circulating calcium levels for changes in albumin
Authors: Hashim I , Joseph J
Published: October 2024

Background

Correcting patients’ circulating calcium to albumin level is a common clinical practice to aid in the evaluation of calcium disorders. More recent studies have called into question the utility of the calculation relative to its ubiquity. The purpose of this study is to re-evaluate the practice of calcium adjustment and thus impact on the interpretation of calcium level.

Methods

Retrospective calcium and albumin levels performed and reported during May 2022 were retrieved. Reference intervals for both serum calcium and albumin were statistically derived using the Hoffman regression method following removal of outliers. Samples exhibiting hypoalbuminemia had their calcium adjusted using the formula (corrected calcium = (0.8 * (derived mean normal albumin - patient's albumin) + calcium). Patients who had their calcium levels adjusted were then compared to the currently in use reference interval to determine if their initial classification of calcium levels was impacted.

Results

Reported calcium and albumin results from a total of 1639 patients (712 males and 927 females) were obtained. Male patients, 137 (19%) were found to exhibit hypoalbuminemia and their calcium levels were adjusted with 15 patients (2% of total) had their initial calcium status change. 13 patients were reclassified from a state of hypocalcemia to normocalcemia (average increase in calcium levels was 0.9 mg/dL), while 2 patients were reclassified as being hypercalcemic. Among females, 151 (16%) found to exhibit hypoalbuminemia had their calcium levels adjusted with 12 patients (1.3% of total) having their initial calcium classification changed. 11 were reclassified from a state of hypocalcemia to normocalcemia (average increase in calcium levels was 0.89 mg/dL) and one patient was reclassified as hypercalcemic. There was no gender specific significant difference in the extent of required calcium adjustment (p= 0.92). Among the 474 black patients 88 (19%) exhibited hypoalbuminemia and mean calcium level of 9.51 mg/dL. Of those 88 patients, 4 were reclassified from a state of hypocalcemia to normocalcemia (average calcium increase of 0.96 mg/dL) and one patient status changed from normocalcemia to hypercalcemia. Furthermore, among the 1094 white patients, 191 (17%) exhibited hypoalbuminemia and had a mean calcium level of 9.38 mg/dL. Among the white patients, 21 (2%) changed from a state of hypocalcemia to normocalcemia (average calcium increase of 0.88 mg/dL). One patient changed from a state of normocalcemia to hypercalcemia. There was no significant racial difference in in the extent of required calcium adjustment (p=0.65).

Conclusions

The practice of adjusting calcium to account for albumin levels lead to changes in patients’ calcium status and thus likely to be of benefit in clinical management. There were no significant gender or racial differences in the relative proportion of changes in calcium status following albumin correction.
A-117 Discordance of CKD stage assignment by different Western and Asian estimated GFR formulae in patients of Eastern India
Authors: Hazra A , Goswami K , Dhar A , Chatterjee N
Published: October 2024

Background

Chronic Kidney Disease (CKD) Stage based on estimated GFR governs the decision between treatment choices eg dialysis, transplant etc. There is no customized eGFR formula for Indians, and hardly any data is available regarding concordance between CKD staging by various formulae on Indian population.

The CKD-EPI-Pakistan formula, developed through a collaboration involving original authors of MDRD/CKD-EPI, is the Asian formula ethno-geographically closest to India. However it has not been tested on Indians.

Methods

We compared 4 eGFR formulae: MDRD(4-factor), CKD-EPI-2009, and CKD-EPI-2021-Creatinine and CKD-EPI-Pakistan for 126 patients undergoing kidney function testing in a tertiary care center in Eastern India. Input for race was non-black in all.

Results

Thirty six of 126 (29%) were discordant by 1 stage between 1 or more formula-pairs, and Kendall's W was 0.034366339 suggesting weak concordance.

Among the MDRD CKD3b and CKD4 cases, CKD-EPI Pakistan re-classified 12% by one stage higher. In the same cases, CKD-EPI-2009 and 2021 both assigned 1 stage lower than MDRD in about 18% and 35% respectively. For MDRD-CKD3a cases too CKD-Epi-Pakistan predicted one stage higher in 50%, whereas both CKD-EPI-2009 and 2021 gave one stage lower in 25%. CKD5 staging were mutually concordant, except Pak formula giving 66% more CKD5.

Conclusions

There is a significant under-staging of CKD stages of Indian patients using western CKD-EPI equations compared to MDRD, whereas CKD-EPI-Pakistan over-stages them especially in the severe stages. If Asian CKD-EPI-Pakistan is considered biologically appropriate for Indians, about 20-30% of treatment-needing patients might currently be under-classified and denied life-saving treatment modalities e.g. Dialysis/CRRT/Transplant, and it might become worse if CKD-EPI 2009 or 2021 is adapted instead of MDRD, especially for higher CKD Grades.

The mutual discordance highlights urgent need of having formulae customized for Indian population validated over a large number of patients locally using measured GFR.
A-127 Stability of Ionized Calcium in Blood Gas Specimens
Authors: Reust J , Poventud-Fuentes I , Patel K
Published: October 2024

Background

Ionized calcium monitoring is crucial for monitoring critically ill patients as well as patients undergoing apheresis. According to CLSI C31-A2:2001, the acceptable stability time for all tests to be run on blood gas analyzers in heparinized syringes is thirty minutes from collection. We sought to determine whether the stability of ionized calcium in blood gas samples can be extended to accommodate prolonged transport times.

Methods

Sixty whole blood samples were collected into 1CC syringes containing 23 IU of heparin (Vital Signs, Inc.) and sent to the laboratory for ionized calcium and pH analysis on the Siemens RAPIDLab 1265. If the remaining sample was sufficient, it was set aside for additional testing 40, 60 and 90 minutes after receipt in the laboratory. All samples were kept at room temperature during all timepoints. The three timepoints were compared to the initial reported baseline result and the average percent bias and standard deviation was determined.

Results

When compared to the baseline result, samples analyzed at the 40-, 60-, and 90-minute timepoints showed negligible bias for both pH and ionized calcium. The absolute bias was within +/- 0.6 and +/-0.4 for ionized calcium and pH, respectively.

Conclusions

This study showed that accurate measurements of both ionized calcium and pH can be obtained from blood gas samples collected in heparinized syringes at least till 90 minutes after collection.
A-128 Evaluation of the Analytical Performance of Three Inflammation Related Assays on the Atellica CI Analyzer
Authors: Carter R H , Tyler C , Coward T , Micklitsch C , Arrode-Bruses G , Snyder J
Published: October 2024

Background

The Atellica® CI Analyzer is an automated, high-throughput integrated chemistry and immunoassay analyzer utilizing both Atellica® CH and Atellica® IM Assays. This study evaluated the analytical performance of the the Atellica CH Complement C3 (C3), Complement C4 (C4), and Alpha-1-acid Glycoprotein (AAG) Assays on the Atellica CI Analyzer.

Methods

Precision studies were performed according to CLSI EP05-A3 using native and contrived human serum samples. One aliquot of each sample was tested in duplicate in two runs per day ≥2 hours apart on each analyzer for ≥20 days. Precision was evaluated using three reagent lots on one system. Method comparison (MC) studies were performed using three reagent lots according to CLSI EP09c. Individual native and contrived human serum samples were analyzed using the Atellica CH C3, C4, and AAG Assays on the Atellica CH Analyzer and the Atellica CI Analyzer. LoB and LoD were determined as described in CLSI EP17-A2.

Results

Representative precision and MC results for each assay are listed in the table. For the three assays tested, repeatability and within-lab %CVs were <1.4% and <3.3%, respectively. Slopes determined by the Deming linear regression model were approximately equal to 1. Detection capability for the Atellica CH C3 Assay on the Atellica CI Analyzer was estimated at 0.2 mg/dL (0.00 g/L) and 0.4 mg/dL (0.00 g/L) for LoB, and LoD. For the Atellica CH C4 Assay, LoB and LoD were determined at 0.1 mg/dL (0.00 g/L) and 0.2 mg/dL (0.00 g/L). For the Atellica CH AAG Assay, LoB and LoD were determined at 0.9 mg/dL (0.01 g/L) and 2.0 mg/dL (0.02 g/L).

Conclusions

Evaluation of the Atellica CH C3, C4, and AAG Assays using the Atellica CI Analyzer demonstrated good precision and equivalent performance compared to the same assays on the Atellica CH Analyzer.