Test Duration Research Articles

Viral Kinetics of SARS-CoV-2 in Nursing Home Residents and Staff

Background: Nursing home (NH) residents are at high risk of COVID-19 from exposure to infected staff and other residents. Understanding SARS-CoV-2 viral RNA kinetics in residents and staff can guide testing, isolation, and return to work recommendations. We sought to determine the duration of antigen test and polymerase chain reaction (PCR) positivity in a cohort of NH residents and staff. Methods: We prospectively collected data on SARS-CoV-2 viral kinetics from April 2023 through November 2023. Staff and residents could enroll prospectively or upon a positive test (identified through routine clinical testing, screening, or outbreak response testing). Participating facilities performed routine clinical testing; asymptomatic testing of contacts was performed within 48 hours if an outbreak or known exposure occurred and upon (re-) admission. Enrolled participants who tested positive for SARS-CoV-2 were re-tested daily for 14 days with both nasal antigen and nasal PCR tests. All PCR tests were run by a central lab with the same assay. We conducted a Kaplan-Meier survival analysis on time to first negative test restricted to participants who initially tested positive (day zero) and had at least one test ≥10 days after initially testing positive with the same test type; a participant could contribute to both antigen and PCR survival curves. We compared survival curves for staff and residents using the log-rank test. Results: Twenty-four nursing homes in eight states participated; 587 participants (275 residents, 312 staff) enrolled in the evaluation, participants were only tested through routine clinical or outbreak response testing. Seventy-two participants tested positive for antigen; of these, 63 tested PCR-positive. Residents were antigen- and PCR-positive longer than staff (Figure 1), but this finding is only statistically significant (p=0.006) for duration of PCR positivity. Five days after the first positive test, 56% of 50 residents and 59% of 22 staff remained antigen-positive; 91% of 44 residents and 79% of 19 staff were PCR-positive. Ten days after the first positive test, 22% of 50 residents and 5% of 22 staff remained antigen-positive; 61% of 44 residents and 21% of 19 staff remained PCR-positive. Conclusions: Most NH residents and staff with SARS-CoV-2 remained antigen- or PCR-positive 5 days after the initial positive test; however, differences between staff and resident test positivity were noted at 10 days. These data can inform recommendations for testing, duration of NH resident isolation, and return to work guidance for staff. Additional viral culture data may strengthen these conclusions.Disclosure: Stefan Gravenstein: Received consulting and speaker fees from most vaccine manufacturers (Sanofi, Seqirus, Moderna, Merck, Janssen, Pfizer, Novavax, GSK, and have or expect to receive grant funding from several (Sanofi, Seqirus, Moderna, Pfizer, GSK). Lona Mody: NIH, VA, CDC, Kahn Foundation; Honoraria: UpToDate; Contracted Research: Nano-Vibronix

Thermal response tests on boreholes in multi-layered ground with geothermal gradient

The design of ground source heat pump systems requires knowledge of the properties of the ground and boreholes, which are often measured through thermal response tests (TRTs). Conventional TRT analysis methods apply for uniform ground properties and undisturbed ground temperature. These assumptions become less valid for deeper boreholes, which penetrate more ground layers while the geothermal gradient becomes more important. In multi-layered ground without a geothermal gradient, conventional methods estimate the effective ground thermal conductivity kgr near the thickness-weighted average, but a geothermal gradient adds complications. In the present study simulated TRTs with quasi-steady-state and fully transient models demonstrate that the required test duration for conventional methods may become impractically large as the borehole depth increases. In general, this occurs when the dimensionless parameter |qratio| approaches 1 or less. This parameter represents the ratio of the externally imposed heat injection/extraction rate to the natural heat rate associated with the geothermal gradient. In these cases, the conventional methods do not estimate the thickness-weighted average value of kgr. On the other hand, a fully transient multi-layered ground model can determine the thickness-weighted average value of kgr. This model requires measured fluid vertical temperature profiles to estimate individual layer values of kgr within reasonable uncertainties.

Significant Improvements to Si Calendar Lifetime Using Rapid Electrolyte Screening via Potentiostatic Holds

Silicon-based lithium-ion batteries exhibit severe time-based degradation resulting in poor calendar lives. This has been identified as the major impediment towards commercialization with cycle life considered a solved issue through nanosizing and protective coatings allowing over 1000 cycles of life to be achieved. In this work, rapid screening of sixteen electrolytes for calendar life extension of Si-rich systems (70 wt% Si) is performed using the voltage hold (V-hold) protocol. V-hold significantly shortens the testing duration over the traditional open circuit voltage reference performance test allowing us to screen electrolytes within a span of two months. We find a novel ethylene carbonate (EC) free electrolyte formulation containing lithium hexafluorophosphate (LiPF6) salt, and binary solvent mix of fluoroethylene carbonate (FEC), ethyl methyl carbonate (EMC) that extends calendar life of Si cells as compared to conventional EC based electrolyte. Our coupled experimental-theoretical analysis framework provides a decoupling of the parasitic currents during V-hold, allowing us to extrapolate the capacity loss to predict semiquantitative calendar lifetimes. Subsequently, cycle aging and oxidative stability tests of the EC free system also show enhanced performance over baseline electrolyte.

Improving assay feasibility and biocompatibility of 3D cyclic olefin copolymer microwells by superhydrophilic modification via ultrasonic spray deposition of polyvinyl alcohol

Sample partitioning is a crucial step towards digitization of biological assays on polymer microfluidic platforms. However, effective liquid filling into microwells and long-term hydrophilicity remain a challenge in polymeric microfluidic devices, impeding the applicability in diagnostic and cell culture studies. To overcome this, a method to produce permanent superhydrophilic 3-dimensional microwells using cyclic olefin copolymer (COC) microfluidic chips is presented. The COC substrate is oxidized using UV treatment followed by ultrasonic spray coating of polyvinyl alcohol solution, offering uniform and long-term coating of high-aspect ratio microfeatures. The coated COC surfaces are UV-cured before bonding with a hydrophobic pressure-sensitive adhesive to drive selective filling into the wells. The surface hydrophilicity achieved using this method remains unchanged (water contact angle of 9°) for up to 6 months and the modified surface is characterized for physical (contact angle & surface energy, morphology, integrity of microfeatures and roughness), chemical composition (FTIR, Raman spectroscopy) and coating stability (pH, temperature, time). To establish the feasibility of the modified surface in biological applications, PVA-coated COC microfluidic chips are tested for DNA sensing (digital LAMP detection of CMV), and biocompatibility through protein adsorption and cell culture studies (cell adhesion, viability, and metabolic activity). Kidney and breast cells remained viable for the duration of testing (7 days) on this modified surface, and the coating did not affect the protein content, morphology or quality of the cultured cells. The ultrasonic spray coated system, coating with 0.25 % PVA for 15 cycles with 0.12 A current after UV oxidation, increased the surface energy of the COC (naturally hydrophobic) from 22.04 to 112.89 mJ/m2 and improved the filling efficiency from 40 % (native untreated COC) to 94 % in the microwells without interfering with the biocompatibility of the surface, proving to be an efficient, high-throughput and scalable method of microfluidic surface treatment for diagnostic and cell growth applications.

Telerehabilitation improves cardiorespiratory and muscular fitness and body composition in older people with post-COVID-19 syndrome.

The effects of post-coronavirus disease 2019 (COVID-19) syndrome on the cardiorespiratory and muscular fitness in older people are of utmost relevance. This study aimed to evaluate the effects of a 12-week telerehabilitation programme on cardiorespiratory and muscular fitness and body composition in older patients with post-COVID-19 syndrome. One hundred twenty older patients with post-COVID-19 syndrome were randomly assigned to one of two groups: patients who carried out the telerehabilitation programme (n=60; age: 65.0±5.2; female: 14.2%) and a control group (n=60; age: 64.3±5.0; female: 24.5%). An incremental cardiopulmonary exercise testing, isokinetic strength test, and bioelectrical impedance analysis were performed to compare cardiorespiratory and muscle strength responses and body composition between telerehabilitation and control groups. A significant increase in the cardiopulmonary exercise testing duration was found in the telerehabilitation group compared to the control group (mean difference=88.9s, P=0.001). Peak oxygen uptake increased in the telerehabilitation group (mean difference=3.0mL·kg-1·min-1, P<0.001) and control group (mean difference=1.9mL·kg-1·min-1, P<0.001). Power output in cycle ergometer (mean difference=25.9 watts, P<0.001), fat free mass (mean difference=2.1kg, P=0.004), soft lean mass (mean difference=2.1kg, P=0.003), and skeletal muscle mass (mean difference=1.4kg, P=0.003) only increased in the telerehabilitation group. A significant increase in the power output was observed in the telerehabilitation group compared with the control group in both lower limbs after isokinetic strength test of the leg extension at a speed of 60° (right: mean difference=18.7 watts, P=0.012; left: mean difference=15.3 watts, P=0.010). The peak torque of right leg extension increased only in the telerehabilitation group after isokinetic strength test at a speed of 60° (mean difference=13.1N·m, P<0.001). A significant increase in the power output was observed in the telerehabilitation group compared with the control group in the left leg extension after isokinetic strength test at a speed of 180° (mean difference=30.2 watts, P=0.003). The telerehabilitation programme improved cardiorespiratory and muscular fitness, and body composition in older patients with post-COVID-19 syndrome to a greater extent than a control group. The telerehabilitation programmes may be an alternative to improve the sequelae of post-COVID-19 syndrome in older patients.

Digital symbol-digit modalities test with modified flexible protocols in patients with CNS demyelinating diseases

Cognitive impairment (CI) is prevalent in central nervous system demyelinating diseases, such as multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). We developed a novel tablet-based modified digital Symbol Digit Modalities Test (MD-SDMT) with adjustable protocols that feature alternating symbol-digit combinations in each trial, lasting one or two minutes. We assessed 144 patients (99 with MS and 45 with NMOSD) using both MD-SDMT protocols and the traditional paper-based SDMT. We also gathered participants’ feedback through a questionnaire regarding their preferences and perceived reliability. The results showed strong correlations between MD-SDMT and paper-based SDMT scores (Pearsons correlation: 0.88 for 2 min; 0.85 for 1 min, both p < 0.001). Among the 120 respondents, the majority preferred the digitalized SDMT (55% for the 2 min, 39% for the 1 min) over the paper-based version (6%), with the 2 min MD-SDMT reported as the most reliable test. Notably, patients with NMOSD and older individuals exhibited a preference for the paper-based test, as compared to those with MS and younger patients. In summary, even with short test durations, the digitalized SDMT effectively evaluates cognitive function in MS and NMOSD patients, and is generally preferred over the paper-based method, although preferences may vary with patient characteristics.

Characterization of atmospheric pressure plasma deposited (APPD) coatings to improve the friction behavior of thermoplastic surfaces

Achieving a significant friction reduction is crucial for using thermoplastic materials as substrates in tribological applications and presents an eligible alternative to the use of light metals. In this study, previously developed MoS2/graphite/zinc composite coatings, applied by an atmospheric pressure plasma deposition (APPD) process, were investigated to extend the understanding of their characteristics and the influence of the process and environmental parameters on friction behavior. Tribological tests were conducted in ambient conditions and at elevated temperatures (110 °C) to study the friction behavior under application-oriented conditions. The presence of atmospheric oxygen during the deposition process was shown to influence the durability of the coatings, which motivated the application of an inert gas atmosphere for the coating deposition. A novel shrouding plasma nozzle was introduced, which further lowered the friction coefficients. The oxidizing effect of the plasma spray deposition was studied with X-ray photoelectron spectroscopy to investigate the strong impact of the deposition current on the friction behavior and durability of the deposited coatings. Coating composition, morphology, and the effects of the tribological testing were evaluated using optical microscopy, 3D surface measurements, scanning electron microscopy, X-ray diffraction, and nanoindentation. The fabricated coatings with thicknesses in the 10 μm range and good adhesion on the polyamide substrate were stable under extended testing durations and at elevated temperatures and accomplished a significant friction reduction compared to the uncoated polyamide. Thus, APPD-fabricated MoS2/graphite/zinc coatings represent an excellent candidate for low-friction applications of thermoplastic substrates.

Two-parameter C-history method: A fast and accurate method for determining the characteristic parameters of formaldehyde/VOC early-stage emissions from building materials

With the worsening indoor air quality in developing countries, more and more attention is being paid to indoor air pollution, especially formaldehyde and volatile organic compounds (VOCs) emitted from indoor building materials. A series of methods, such as the C-history method, have been proposed to determine the mechanistic parameters of formaldehyde and other VOC emissions. However, these methods require a relatively long test duration (at least 3 days) and may yield a multi-solution problem for these parameters. Therefore, we have developed a novel method, the two-parameter C-history method, to overcome these limitations by measuring the two early-stage emission characteristic parameters for formaldehyde/VOCs. The experimental results validate the accuracy of this method for different building materials and showed that the test duration can be substantially shortened to within 12 h. Based on this, we propose a new method to quickly predict the two emission characteristic parameters at different temperatures. We optimize the experimental parameters and discuss their influence to further improve accuracy. This method will be useful in engineering applications.

Association of digital device usage and dry eye disease in school children.

To investigate the influence of digital device use (computers, laptops, tablets, smartphones) on dry eye disease (DED) in a pediatric population. This was a cross-sectional study. School children studying in grades 5-9 at two private schools in the city of Ahmedabad, the capital city of Gujarat, India were invited to participate in the study. In this study, 462 children underwent ocular examination including tear film breakup time (TBUT) and Schirmer's test. Questionnaires were administered for collecting information on the type and duration of digital device usage separately for academic and leisure activities and the Ocular Surface Disease Index (OSDI) score. The mean age of participants was 11.2 + 1.4 years, and 63% were boys. The mean OSDI score was 37.2 + 11.8, and 90.5% had symptoms of DED. Children with moderate to severe DED (n = 88, 19%) had longer daily duration of device use and lower Schirmer's test and TBUT values compared to children with mild DED (P = 0.001). A cumulative exposure time of more than 3-3.5 h per day had a significantly increased risk of DED. Multivariable logistic regression analysis showed that increment in computer usage (odds ratio [OR] 1.94 for every half an hour increase, 95% confidence interval [CI] = 1.2-3.1) and children studying in higher grades (OR 1.30, 95% CI = 1.1-1.6) had a higher risk of moderate to severe dry eye. Cumulative device exposure time of more than 3-3.5 h per day had a significantly increased risk of pediatric DED. Children with an increment in computer usage by half an hour per day had a higher chance of experiencing moderate to severe dry eye. Policymakers should aim to restrict the screen time below 3 h on a daily basis.

Effects of mechanical surface pre-treatment on integrity and corrosion of bare and coated AA6082 substrates

In this study, two classes of surface pre-treatment methods, namely three blast-cleaning methods with different abrasive materials (for initial preparation) and three mechanical methods (for repair applications) were applied to study their effects on surface morphology, composition, and corrosion of AA6082 substrates in artificial seawater. Coating adhesion and coating corrosion protection ability were investigated by applying a single-layer epoxy coating (250 μm dry film thickness) onto the substrates.The mechanical methods delivered cleaner surfaces with more regular surface morphologies, whereas the blast-cleaning methods revealed less clean surfaces and more irregular surface morphologies. The latter methods promoted the detrimental embedment of abrasive particles into the substrates. The corrosion performance of the pre-treated substrates was worse after blast-cleaning compared to mechanical treatments. However, all methods met the adhesion requirements for offshore applications. Regarding coating degradation, only the filiform corrosion test delivered meaningful results, whereas the duration of the cyclic corrosion test (3000 h) was too short to distinguish between the different methods because of neglectable degradation. Mechanical interlocking and isotropic surface morphologies are found to be more important for coating performance than a cleaner surface, and the remains of blasting material were neglectable too.

Functional lower extremity strength influences stepping strategy in community-dwelling older adults during single and dual-task walking

As age increases, a decline in lower extremity strength leads to reduced mobility and increased fall risks. This decline outpaces the age-related reduction in muscle mass, resulting in mobility limitations. Older adults with varying degrees of mobility-disability use different stepping strategies. However, the link between functional lower extremity strength and stepping strategy is unknown. Therefore, understanding how age-related reductions in functional lower extremity strength influence stepping strategy is vital to unraveling mobility limitations. Twenty participants (17F, 72 ± 6 years) were recruited and tested at a local community event. Participants were outfitted with inertial measurement units (IMU) and walked across a pressurized walkway under single and dual motor task conditions (walking with and without carrying a tray with water) at their usual and fast speeds. Participants were dichotomized into normal (11) or low functional strength groups (9) based on age-specific normative cutoffs using the instrumented 5-repetition Sit-to-Stand test duration. Our study reveals that older adults with normal strength prefer adjusting their step time during walking tasks, while those with reduced strength do not exhibit a preferred stepping strategy. This study provides valuable insights into the influence of functional lower extremity strength on stepping strategy in community-dwelling older adults during simple and complex walking tasks. These findings could aid in diagnosing gait deviations and developing appropriate treatment or management plans for mobility disability in older adults.

Rating of Perceived Exertion: A Large Cross-Sectional Study Defining Intensity Levels for Individual Physical Activity Recommendations

BackgroundPhysical inactivity is a growing risk factor worldwide, therefore getting people into sports is necessary. When prescribing physical activity, it is essential to recommend the correct training intensities. Cardiopulmonary exercise testing (CPX) enables precise determination of individuals’ training intensities but is unavailable for a broad population. Therefore, the Borg scale allows individuals to assess perceived exertion and set their intensity easily and cost-efficiently. In order to transfer CPX to rating of perceived exertion (RPE), previous studies investigated RPE on specific physiological anchors, e.g. blood lactate (bLa) concentrations, but representativeness for a broad population is questionable. Some contradictory findings regarding individual factors influencing RPE occur, whereas univariable analysis has been performed so far. Moreover, a multivariable understanding of individual factors influencing RPE is missing. This study aims to determine RPE values at the individual anaerobic threshold (LT2) and defined bLa concentrations in a large cohort and to evaluate individual factors influencing RPE with multivariable analysis.MethodsCPX with bicycle or treadmill ergometer of 6311 participants were analyzed in this cross-sectional study. RPE values at bLa concentrations 2 mmol/l, 3 mmol/l, 4 mmol/l, and LT2 (first rise in bLa over baseline + 1.5 mmol/l) were estimated by spline interpolation. Multivariable cumulative ordinal regression models were performed to assess the influence of sex, age, type of ergometry, VO2max, and duration of exercise testing on RPE.ResultsMedian values [interquartile range (IQR)] of the total population were RPE 13 [11; 14] at 2 mmol/l, RPE 15 [13; 16] at 3 mmol/l, RPE 16 [15; 17] at 4 mmol/l, and RPE 15 [14; 16] at LT2. Main influence of individual factors on RPE were seen especially at 2 mmol/l: male sex (odds ratio (OR) [95%-CI]: 0.65 [0.587; 0.719]), treadmill ergometry (OR 0.754 [0.641; 0.886]), number of stages (OR 1.345 [1.300; 1.394]), age (OR 1.015 [1.012; 1.018]), and VO2max (OR 1.023 [1.015; 1.030]). Number of stages was the only identified influencing factor on RPE at all lactate concentrations/LT2 (3 mmol/l: OR 1.290 [1.244; 1.336]; 4 mmol/l: OR 1.229 [1.187; 1.274]; LT2: OR 1.155 [1.115; 1.197]).ConclusionOur results suggest RPE ≤ 11 for light intensity, RPE 12–14 for moderate intensity, and RPE 15–17 for vigorous intensity, which slightly differs from the current American College of Sports Medicine (ACSM) recommendations. Additionally, we propose an RPE of 15 delineating heavy and severe intensity domain. Age, sex, type of ergometry, duration of exercise, and cardiopulmonary fitness should be considered when recommending individualized intensities with RPE, primarily at lower intensities. Therefore, this study can be used as a new guideline for prescribing individual RPE values in the clinical practice, predominantly for endurance type exercise.

Maximising the benefits of NIR rapid analysis for sugarcane mill laboratories

Obtaining, training and retaining laboratory personnel for Australian sugarcane mills is a growing concern within the industry. The test duration for some primary laboratory methods is often too long to make the required process adjustments in time, such as altering the high-grade centrifugal settings. Once established, near-infrared (NIR) laboratory instruments using mature calibrations provide many advantages that address both issues, such as ease of use, speed of analysis, multiple constituent results generated in one scan for multiple mill products, and precision and accuracy of results. However, an initial “development” procedure is required to achieve mature calibrations, followed by an ongoing “operation” procedure. This paper demonstrates how the “development” and “operation” procedures were successfully applied to two sugarcane mills. A previously generated globalised calibration, created from various mill instruments and sample populations, was used to develop a mature localised calibration specific to the mill sample sets and their respective laboratory instruments. Stored raw sugar (pol. sugar, water), fresh raw sugar (pol. sugar, water), and molasses (dry substance, sucrose, and final molasses sucrose) were the targeted products considered for the two mills. The “development” methodology used as much data as was practical to rapidly represent the mill sample populations until the equation achieved stability, i.e. the standard error of prediction (SEP) was less than the error control limit (ECL) for each product’s constituent equations. Once matured, the “operation” methodology was implemented, where only 10% of the total sample population scanned by the NIR instrument was required for validation to monitor and maintain prediction performance. Novel software tools were implemented to improve the efficiency of the validation process. Both mill instruments underwent the “development” procedure during the 2019 season. Multiple NIR calibration updates were applied to achieve SEPs that were within or converging to their respective ECLs. The “operation” procedure was implemented during the 2020 and 2021 seasons, where only a single-seasonal NIR calibration update was required for each mill for all product constituent equations to meet the required prediction performance criteria. Providing reliable NIR test results within such short time frames allowed near real-time decisions to be made by process operators with minimal training requirements. The two-stage NIR development/operation methodology can be employed with the appropriate data for similar products.

Comparison of Foraging Interactive D-prime and Angular Indication Measurement Stereo with different methods to assess stereopsis

Purpose Stereopsis is a critical visual function, however clinical stereotests are time-consuming, coarse in resolution, suffer memorization artifacts, poor repeatability, and low agreement with other tests. Foraging Interactive D-prime (FInD) Stereo and Angular Indication Measurement (AIM) Stereo were designed to address these problems. Here, their performance was compared with 2-Alternative-Forced-Choice (2-AFC) paradigms (FInD Stereo only) and clinical tests (Titmus and Randot) in 40 normally-sighted and 5 binocularly impaired participants (FInD Stereo only). Methods During FInD tasks, participants indicated which cells in three 4*4 charts of bandpass-filtered targets (1,2,4,8c/° conditions) contained depth, compared with 2-AFC and clinical tests. During the AIM task, participants reported the orientation of depth-defined bars in three 4*4 charts. Stereoscopic disparity was adaptively changed after each chart. Inter-test agreement, repeatability and duration were compared. Results Test duration was significantly longer for 2-AFC (mean = 317s;79s per condition) than FInD (216s,18s per chart), AIM (179s, 60s per chart), Titmus (66s) or RanDot (97s). Estimates of stereoacuity differed across tests and were higher by a factor of 1.1 for AIM and 1.3 for FInD. No effect of stimulus spatial frequency was found. Agreement among tests was generally low (R2 = 0.001 to 0.24) and was highest between FInD and 2-AFC (R2 = 0.24;p&lt;0.01). Stereoacuity deficits were detected by all tests in binocularly impaired participants. Conclusions Agreement among all tests was low. FInD and AIM inter-test agreement was comparable with other methods. FInD Stereo detected stereo deficits and may only require one condition to identify these deficits. AIM and FInD are response-adaptive, self-administrable methods that can estimate stereoacuity reliably within one minute.

Effect of flexible membrane in triaxial test on the mechanical behaviour of rockfill material using Discrete Element Method

The investigation of rockfill materials poses challenges due to their large particle size, associated high cost, and long laboratory testing duration. As a result, empirical correlations based on historical experimental studies are commonly used to design and analyse rockfill structures. However, the extensive use of rockfill in a wide range of applications and limited understanding of its mechanical behaviour emphasize the need for further research. These make it necessary to develop a robust technique capable of capturing key parameters such as particle shape and breakage, allowing for the simulation and study of large-scale assemblies with realistic boundary conditions. Given that the behaviour of rockfill is highly scale-dependent, primarily due to particle breakage, the simplified laboratory tests on the scaled-down assemblies can be misleading. Particle breakage is a fundamental phenomenon in the mechanical behaviour of rockfill and significantly affects shear strength, deformability, and porosity under different stress levels. The particle breakage is influenced by factors such as the rockfill’s maximum particle size, mineralogy, particle shape, gradation, and confining stresses. This study adopts a computationally efficient breakage method called the Modified Particle Replacement Method (MPRM) based on the Discrete Element Method. A Tile-Based Flexible Membrane (TBFM) for triaxial test modelling has been developed by employing segmental rectangular walls to create a deformable membrane. The effects of critical parameters, including particle shape, confining stress, membrane resolution, degree of flexibility, and the characteristic strength of the particles, are examined. The findings of the combined MPRM-TBFM approach demonstrate the significant influence of membrane flexibility on volumetric-related behaviour.Graphical

Arrangement of Nondestructive Tests for Technical Inspection Process of Electrofusion Weld in Gas Polyethylene Pipe

Due to the reduction of operational costs, Non-corrosiveness, and ease of implementation, polyethylene pipes are a suitable replacement for steel pipes in gas distribution networks. Considering the irreversible events of gas leakage, effective and feasible non-destructive testing of electrofusion welding is an essential factor to avoid the hazards of gas leakage. To control the quality of welds, the nature of the electrofusion structure leads us to manufacture vacuum boxes, internal pressure devices, and Tapping Saddle Connector for testing polyethylene joint leakages. This article focuses on the sequence of these non-destructive tests to monitor the health of polyethylene electrofusion joint structures under gas network project implementation conditions. To examine the testing chain and the proposed sequence of non-destructive tests, the data gathering process was performed, and with respect to the sensitivity of the electrofusion weld to the operator's skill, welding process, and the condition of the pipe and fittings, in each case the influential factors to find the key parameters were evaluated. The results of laboratory tests in cases of short tests and long-life tests using artificial defects such as slow crack growth with defective samples of on-site joints and defects reported in projects were compared. To validate leak detection, leak location, and leak measurement, weld simulation with finite element and CFD software analysis conforming to real conditions was considered. The test sequence, acceptance criteria, and calibration method of the tools according to EN 1555 standard were argued for performing the final inspection steps. In this perspective, for each leak testing technique, the average type, pressure level, test duration, and finally the acceptance criteria were proposed. The main outcome is the technical specifications for electrofusion weld assessment and baseline risk- based inspection scheme in gas supply projects. In this regard, a database software based on the proposed ITP (Inspection and Testing Plan) has been developed, which is fundamental for monitoring the whole project from the first stage of polyethylene granule control, pipe and fitting manufacture, and gas injection to the final stage in network and commissioning. Operations to determine failure causes and suitability for performance assessment. Another proposed idea is standardizing the recent technical specifications internationally. This idea will be implemented when management realizes that non-destructive testing can lead to cost savings, protection of humans and the environment, and when codes and standards encompass such requirements.

Effectiveness and Safety of Dexmedetomidine in Neonates With Hypoxic Ischemic Encephalopathy Undergoing Therapeutic Hypothermia.

The objective of this study was to evaluate and compare the effectiveness and safety of dexmedetomidine as monotherapy between neonates with mild hypoxic ischemic encephalopathy (HIE) and moderate to severe HIE treated with therapeutic hypothermia (TH). This retrospective study included neonates of gestational age ≥36 weeks with a diagnosis of HIE and undergoing TH between January 2014 and December 2021. Patients were included if they received at least 6 hours of continuous sedation with dexmedetomidine. Baseline characteristics, dose and duration of medication, adverse events, liver and kidney function tests, and hospital course were reviewed. Of the 97 neonates included, 46 had mild, 42 had moderate, and 9 had severe HIE. Dexmedetomidine was initiated at a median 5 hours of life, and the median infusion duration was 77 (46-87) hours. Fifty-two (53.6%) required at least 1 breakthrough opioid or sedative during the first 24 hours of dexmedetomidine infusion. Overall, 40 patients (41.2%) had at least 1 bradycardia episode with heart rate <80 beats/min and 14 patients (14.4%) had heart rate <70 beats/min. Hypotension was experienced by 7 patients (7.2%). Fifty-two patients (53.6%) were intubated in the delivery room and 33/52 (63.5%) were extubated on day of life 1 during dexmedetomidine infusion. Dexmedetomidine as monotherapy was effective and safe sedation for infants with HIE undergoing hypothermia. The most common side effect of dexmedetomidine was bradycardia. -Dexmedetomidine may be considered as first and single agent for neonates with HIE undergoing TH.

An optimised and validated surrogate analyte A-TEEM-PARAFAC-PLS technique for detecting and quantifying the biological oxygen demand in surface water.

A 5-day test duration makes BOD5 measurement unsatisfactory and hinders the development of a quick technique. Protein-like fluorescence peaks show a strong correlation between the BOD characteristics and the fluorescence intensities. For identifying and measuring BOD in surface water, a simultaneous absorbance-transmittance and fluorescence excitation-emission matrices (A-TEEM) method combined with PARAFAC (parallel factor) and PLS (partial least squares) analyses was developed using a tyrosine and tryptophan (tyr-trpt) mix as a surrogate analyte for BOD. The use of a surrogate analyte was decided upon due to lack of fluorescent BOD standards. Tyr-trpt mix standard solutions were added to surface water samples to prepare calibration and validation samples. PARAFAC analysis of excitation-emission matrices detected the tyr-trpt mix in surface water. PLS modelling demonstrated significant linearity (R2 = 0.991) between the predicted and measured tyr-trypt mix concentrations, and accuracy and robustness were all acceptable per the ICH Q2 (R2) and ASTM multivariate calibration/validation procedures guidelines. Based on a suitable and workable surrogate analyte method, these results imply that BOD can be detected and quantified using the A-TEEM-PARAFAC-PLS method. Very positive comparability between tyr-trypt mix concentrations was found, suggesting that tyr-trypt mix might eventually take the place of a BOD-based sampling protocol. Overall, this approach offers a novel tool that can be quickly applied in water treatment plant settings and is a step in supporting the trend toward rapid BOD determination in waters. Further studies should demonstrate the wide application of the method using real wastewater samples from various water treatment facilities.

Accelerated testing of the Wear Behavior of 3D-printed Spur Gears

This paper presents the results of an in-depth investigation of 3D-printed plastic gears made of ABS, PLA, and annealed PLA. Wear tests performed on a specialized rig underscore the superior wear resistance of ABS gears, while the annealing process shows a modest improvement in PLA gear durability. The novelty of this study is a comprehensive evaluation of the wear behavior of different 3D printed materials under different loading conditions. This study introduces an innovative accelerated testing method, emphasizing efficiency in product development through reduced testing durations and adaptability to various scenarios.

Exercise capacity and cardiac allograft ischemic time in recent heart transplant recipients

BackgroundProlonged ischemic times (IT) for transplant hearts transported under cold storage conditions are associated with an increased risk of mortality, however the impact of IT on functional outcomes, such as exercise capacity, is not fully understood. This prospective, observational cohort study aimed to determine the association between exercise capacity, a strong predictor for post-transplant survival, and relatively longer IT. MethodsThirty heart transplant recipients were grouped dichotomously according to relatively longer (>180 min) or shorter (≤180 min) IT. A cardiopulmonary exercise test (CPET) was performed post-transplant upon entry into cardiac rehabilitation, during which peak VO2 was measured using a metabolic cart. CPET variables, including exercise capacity and test duration, were compared between groups. ResultsThis cohort was predominantly male (n=22, 73%) with a median age of 57.5 years [Q1-Q3: 54.0 - 65.0]). Baseline demographics and characteristics were similar between groups aside from UNOS listing status, in which patients listed as Status 1 or 2 were more likely to have long IT. Twelve (40%) participants received a donor heart with long IT. Surprisingly, higher peak VO2 was observed in those with long (15.0±2.8) than short (13.1±3.7) IT (p=0.009). However, CPET duration was significantly shorter in recipients with a long IT (6.3 vs. 7.7 minutes, p=0.048) despite similar time since transplant, rate of perceived exertion, protocol performed, and exercise capacity. ConclusionsIn this modest-sized cohort, exercise capacity was higher in heart transplant recipients with donor IT >180 minutes compared to those with IT ≤180 minutes. However, exercise duration was significantly shorter in those with relatively longer IT.