Effects of perfluoroalkyl substances (PFAS) on antioxidant depletion from a high-density polyethylene geomembrane.

To safely contain Per-and Polyfluoroalkyl substances (PFAS) in municipal solid waste landfills and contaminated soil monofills, it is necessary to understand how these substances interact with components of engineered systems designed to contain them. This paper examines the interaction between one of the most critical components of the system: a high-density polyethylene (HDPE) geomembrane. The same geomembrane is immersed in PFAS solution and synthetic municipal solid waste leachate containing PFAS for 2.5 years, and the effects of PFAS on antioxidant depletion time is examined. The geomembrane is incubated in ovens at 85-40 °C to obtain data for Arrhenius predictions at typical landfill temperatures. When exposed to PFAS solution alone, the antioxidant depletion times are smaller than when the same geomembrane is immersed in synthetic municipal solid waste leachate alone. The combination of the two has a synergistic effect which leads to an even greater reduction in antioxidant depletion time for this geomembrane, with results showing a 68% decrease in predicted antioxidant depletion time at a typical landfill temperature of 35 °C when PFAS is present in leachate. This study highlights the need to consider the potential impact of PFAS on the service life of geomembranes used to contain them.

Does carbon footprint reduction impair mechanical properties and service life of concrete?

The aim of this study is to evaluate how much the changes in the concrete mix design, which enable carbon footprint reduction, are impacting mechanical properties and predicted service life of concrete structure. The starting point of this study was concrete mix used in a recent reinforced concrete Peljesac Bridge in the Adriatic. In the first round of experiments the amount of cement in this initial mix was significantly lowered, without jeopardising workability of the mix. In the second round, the main part of the cement was substituted with the combination of fly ash and limestone or calcined clay and limestone. All supplementary cementitious materials used were sourced in the region of the structure. The calcined clays used in this study were collected locally and found to have a low kaolin content. On all mixes fresh and mechanical properties were tested to ensure that the requested equal or better workability and mechanical stability were reached. Furthermore, on each mix chloride migration was tested to evaluate the resistance of mix to chloride penetration. All mixtures were evaluated based on the overall performance considering mechanical, durability, and carbon footprints. The results indicate that the total cement content had a significant effect on durability and thus service life. The bridge mix design was determined to be 'over designed,' as all alternative mixes achieved a similar or higher sustainability index with lower amount of cement. Supplementary Information: The online version contains supplementary material available at 10.1617/s11527-022-02090-9.

EDS Microanalysis of Unhydrated Blast Furnace Slag Grains in Field Concrete with Different Service Life.

Because the essential quality metrics of blast furnace slag are based on its oxide composition, the determination of chemical compositions of unhydrated slag grains in an aged concrete could be useful for understanding its past performance and in predicting the remaining service life of existing slag-bearing concrete. In this research, the authors explored the feasibility of using standard-based energy-dispersive X-ray spectroscopy (EDS) microanalysis, in tandem with electron imaging, as a tool for quantitative measurement of the chemical composition of blast furnace slag grains in cement/concrete. In the experimental study, seven concrete samples representing various service life durations were collected in the Netherlands. The microanalysis results of the samples revealed that the change in slag chemistry is insignificant for samples B (1985) to F (2006); however, elevated CaO and SiO2 contents are found in slag used for sample G (2015), opposite to that of Al2O3 and MgO. After discussing compositional characterization, the paper discusses favorable microanalysis protocols for acceptable elemental quantification accuracy. It was concluded that quantitative EDS microanalysis is a strong tool to characterize the chemical composition of unhydrated slag used in field concrete, which could potentially contribute to understanding the correlations between composition and long-term performance in slag concrete structures.

Current Status and Applications for Hydraulic Pump Fault Diagnosis: A Review.

To implement Prognostics Health Management (PHM) for hydraulic pumps, it is very important to study the faults of hydraulic pumps to ensure the stability and reliability of the whole life cycle. The research on fault diagnosis has been very active, but there is a lack of systematic analysis and summary of the developed methods. To make up for this gap, this paper systematically summarizes the relevant methods from the two aspects of fault diagnosis and health management. In addition, in order to further facilitate researchers and practitioners, statistical and comparative analysis of the reviewed methods is carried out, and a future development direction is prospected.

Prediction Method of Soft Fault and Service Life of DC-DC-Converter Circuit Based on Improved Support Vector Machine.

A data-driven prediction method is proposed to predict the soft fault and estimate the service life of a DC-DC-converter circuit. First, based on adaptive online non-bias least-square support-vector machine (AONBLSSVM) and the double-population particle-swarm optimization (DP-PSO), the prediction model of the soft fault is established. After analyzing the degradation-failure mechanisms of multiple key components and considering the influence of the co-degradation of these components over time on the performance of the circuit, the output ripple voltage is chosen as the fault-characteristic parameter. Finally, relying on historical output ripple voltages, the prediction model is utilized to gradually deduce the predicted values of the fault-characteristic parameter; further, in conjunction with the circuit-failure threshold, the soft fault and the service life of the circuit can be predicted. In the simulation experiment, (1) a time-series prediction is made for the output ripple voltage using the model proposed herein and the online least-square support-vector machine (OLS-SVM). Comparative analyses of fitting-assessment indicators of the predicted and experimental curves confirm that our model is superior to OLS-SVM in both modeling efficiency and prediction accuracy. (2) The effectiveness of the service life prediction method of the circuit is verified.

Simultaneous Determination of Droplet Size, pH Value and Concentration to Evaluate the Aging Behavior of Metalworking Fluids.

Metalworking fluids (MWFs) are widely used to cool and lubricate metal workpieces during processing to reduce heat and friction. Extending a MWF's service life is of importance from both economical and ecological points of view. Knowledge about the effects of processing conditions on the aging behavior and reliable analytical procedures are required to properly characterize the aging phenomena. While so far no quantitative estimations of ageing effects on MWFs have been described in the literature other than univariate ones based on single parameter measurements, in the present study we present a simple spectroscopy-based set-up for the simultaneous monitoring of three quality parameters of MWF and a mathematical model relating them to the most influential process factors relevant during use. For this purpose, the effects of MWF concentration, pH and nitrite concentration on the droplet size during aging were investigated by means of a response surface modelling approach. Systematically varied model MWF fluids were characterized using simultaneous measurements of absorption coefficients µa and effective scattering coefficients µ's. Droplet size was determined via dynamic light scattering (DLS) measurements. Droplet size showed non-linear dependence on MWF concentration and pH, but the nitrite concentration had no significant effect. pH and MWF concentration showed a strong synergistic effect, which indicates that MWF aging is a rather complex process. The observed effects were similar for the DLS and the µ's values, which shows the comparability of the methodologies. The correlations of the methods were R2c = 0.928 and R2P = 0.927, as calculated by a partial least squares regression (PLS-R) model. Furthermore, using µa, it was possible to generate a predictive PLS-R model for MWF concentration (R2c = 0.890, R2P = 0.924). Simultaneous determination of the pH based on the µ's is possible with good accuracy (R²c = 0.803, R²P = 0.732). With prior knowledge of the MWF concentration using the µa-PLS-R model, the predictive capability of the µ's-PLS-R model for pH was refined (10 wt%: R²c = 0.998, R²p = 0.997). This highlights the relevance of the combined measurement of µa and µ's. Recognizing the synergistic nature of the effects of MWF concentration and pH on the droplet size is an important prerequisite for extending the service life of an MWF in the metalworking industry. The presented method can be applied as an in-process analytical tool that allows one to compensate for ageing effects during use of the MWF by taking appropriate corrective measures, such as pH correction or adjustment of concentration.

[Influence Factor and Evaluation Discuss of IVD Medical Equipment Service Life].

In order to help the IVD medical equipment manufacturers to establish the service life of products scientifically, we analyze the main factors that may affect the service life of IVD medical equipment in accordance with the guiding principles for technical review of active medical devices issued by the center of medical device evaluation of NMPA, and focuse on an evaluation method of accelerated fatigue test, in order to standardize and guide the IVD medical equipment manufacturers to evaluate and formulate the product service life scientifically.

[Study on PET/CT Service Life Based on Key Components].

In this study, through the analysis of the composition of domestic large radioactive medical equipment PET/CT and the characteristics of each subsystem, combing the vulnerable spots, according to the standard requirements of PET/CT for 10 years in its service life, we research the PET/CT service life's effectiveness. Firstly, this study introduces the concept of service life, the relationship between service life and risk analysis, the pivotal system composition of PET/CT, the importance of reliability of each component, the traditional test method to verify its reliability is researched. This study suggests a test procedure and method to prove the reliability of various components of PET/CT equipment during the service life. This method is described in detail, and the specific test process in practical engineering application is discussed, which proves that it is beneficial to ensure the effectiveness of PET/CT during the service life.

An Ag2 S@ZnS-coated fiber for efficient, long-life solid-phase microextraction of polycyclic aromatic hydrocarbons in water.

Although an efficient and stable fiber coating is essential for the development of solid-phase microextraction technique, it remains a challenging prospect. Herein, an inorganic nanocomposite material Ag2 S@ZnS was prepared and used as a coating for fibers to detect polycyclic aromatic hydrocarbons in water samples in combination with a GC with flame ionization detector. Compared with a single ZnS material, the Ag2 S@ZnS composite shows many uneven nano-protrusions on the surface of the microspheres. In conjunction with the relatively scattered microstructure of the coating and the effective anion-π interaction formed between ZnS and the hydrocarbons, it has a large specific surface area, fast diffusion of the target molecule on its surface, and appropriate adsorption of the target molecules; therefore, it exhibits good extraction efficiency for the hydrocarbons. Under optimal conditions, the proposed analytical method exhibits superior performance with good linearity (0.01-500 µg/L) and low limits of detection (0.001-0.200 µg/L). Combined with high thermal, chemical, and mechanical stability, the service life of the coating was improved and could be used 200 times without a significant reduction in the extraction performance, and at least 2000 extraction-desorption cycles can be achieved. Satisfactory results were also obtained for the real samples.

Prediction of the service life of surgical instruments from the surgical instrument management system log using radio frequency identification.

BACKGROUND: Bar code- or radio frequency identification (RFID)-based medical instrument management systems have gradually been introduced in the field of surgical medicine for the individual management and identification of instruments. We hypothesized that individual management of instruments using RFID tags can provide previously unavailable information, particularly the precise service life of an instrument. Such information can be used to prevent medical accidents caused by surgical instrument failure. This study aimed to predict the precise service life of instruments by analyzing the data available in instrument management systems. METHODS: We evaluated the repair history of instruments and the usage count until failure and then analyzed the data by the following three methods: the distribution of the instrument usage count was determined, an instrument failure probability model was generated through logistic regression analysis, and survival analysis was performed to predict instrument failure. RESULTS: The usage count followed a normal distribution. Analysis showed that instruments were not used uniformly during surgery. In addition, the Kaplan-Meier curves plotted for five types of instruments showed significant differences in the cumulative survival rate of different instruments. CONCLUSIONS: The usage history of instruments obtained with RFID tags or bar codes can be used to predict the probability of instrument failure. This prediction is significant for determining the service life of an instrument. Implementation of the developed model in instrument management systems can help prevent accidents due to instrument failure. Knowledge of the instrument service life will also help in developing a purchase plan for instruments to minimize wastage.

Evaluation of data-driven models for predicting the service life of concrete sewer pipes subjected to corrosion.

Concrete corrosion is one of the most significant failure mechanisms of sewer pipes, and can reduce the sewer service life significantly. To facilitate the management and maintenance of sewers, it is essential to obtain reliable prediction of the expected service life of sewers, especially if that is based on limited environmental conditions. Recently, a long-term study was performed to identify the controlling factors of concrete sewer corrosion using well-controlled laboratory-scale corrosion chambers to vary levels of H2S concentration, relative humidity, temperature and in-sewer location. Using the results of the long-term study, three different data-driven models, i.e. multiple linear regression (MLR), artificial neural network (ANN), and adaptive neuro fuzzy inference system (ANFIS), as well as the interaction between environmental parameters, were assessed for predicting the corrosion initiation time (ti) and corrosion rate (r). This was performed using the sewer environmental factors as the input under 12 different scenarios after allowing for an initiation corrosion period. ANN and ANFIS models showed better performance than MLR models, with or without considering the interactions between environmental factors. With the limited input data available, it was observed that ti prediction by these models is quite sensitive, however, they are more robust for predicting r as long as the H2S concentration is available. Using the H2S concentration as a single input, all three data driven models can reasonably predict the sewer service life.

Defining clogging potential for permeable concrete.

Permeable concrete is used to reduce urban flooding as it allows water to flow through normally impermeable infrastructure. It is prone to clogging by particulate matter and predicting the long-term performance of permeable concrete is challenging as there is currently no reliable means of characterising clogging potential. This paper reports on the performance of a range of laboratory-prepared and commercial permeable concretes, close packed glass spheres and aggregate particles of varying size, exposed to different clogging methods to understand this phenomena. New methods were developed to study clogging and define clogging potential. The tests involved applying flowing water containing sand and/or clay in cycles, and measuring the change in permeability. Substantial permeability reductions were observed in all samples, particularly when exposed to sand and clay simultaneously. Three methods were used to define clogging potential based on measuring the initial permeability decay, half-life cycle and number of cycles to full clogging. We show for the first time strong linear correlations between these parameters for a wide range of samples, indicating their use for service-life prediction.

Development of a Hydrogen Sulfide End-of-Service-Life Indicator for Respirator Cartridges Using Cobinamide.

An inexpensive paper-based sensor was developed for detecting low ppm concentrations of hydrogen sulfide gas. A piece of filter paper containing aquohydroxocobinamide [OH(H2O)Cbi] was placed on the end of a bifurcated optical fiber, and the reflectance spectrum of the OH(H2O)Cbi was monitored during exposure to 10.0 ppm hydrogen sulfide gas (NIOSH recommended exposure limit). Reaction of sulfide (HS-) yielded an increase in reflectance from 400-450 nm, and decrease from 470-550 nm. Spectral changes were monitored as a function of time at 25, 50, and 85% relative humidity. Spectral shifts at high-er humidity suggested reduction of the Cbi(III) compound. The sensor was used to detect hydrogen sulfide breakthrough from respirator carbon beds and results correlated well with a standard electrochemical detector. The simple paper-based sensor could provide a real-time end-of-service-life alert for hydrogen sulfide gas.

Evaluation of a passive optical based end of service life indicator (ESLI) for organic vapor respirator cartridges.

A passive visual end of service life indicator (ESLI) for certain organic vapors has been attached to the inside wall of an organic vapor respirator cartridge. The opposite side of the ESLI touches activated carbon inside the cartridge. During use, organic vapors moving through the cartridge adsorb into both the carbon and the ESLI. The cartridge body is clear so that when vapor concentrations meet a certain threshold, the user may observe the progressive development of an indicator bar down the side of the ESLI. The cartridge is deemed ready to change when any part of the indicator bar touches a marked end line. The performance of the ESLI was observed when the cartridge was tested against a variety of organic vapors, exposure concentrations above the minimum indication level, humidities, temperatures, flow rates, and mixtures. In all cases, the ESLI indicated end of service life with more than 10% cartridge service life remaining (which is a NIOSH test criteria). The results were also compared to mathematical predictions of cartridge service life.

Development of a cobinamide-based end-of-service-life indicator for detection of hydrogen cyanide gas.

We describe an inexpensive paper-based sensor for rapid detection of low concentrations (ppm) of hydrogen cyanide gas. A piece of filter paper pre-spotted with a dilute monocyanocobinamide [CN(H2O)Cbi] solution was placed on the end of a bifurcated optical fiber and the reflectance spectrum of the CN(H2O)Cbi was monitored during exposure to 1.0-10.0 ppm hydrogen cyanide gas. Formation of dicyanocobinamide yielded a peak at 583 nm with a simultaneous decrease in reflectance from 450-500 nm. Spectral changes were monitored as a function of time at several relative humidity values: 25, 50, and 85% relative humidity. With either cellulose or glass fiber papers, spectral changes occurred within 10 s of exposure to 5.0 ppm hydrogen cyanide gas (NIOSH recommended short-term exposure limit). We conclude that this sensor could provide a real-time end-of-service-life alert to a respirator user.

Breakthrough curves for toluene adsorption on different types of activated carbon fibers: application in respiratory protection.

Activated carbon fibers (ACF) are considered viable alternative adsorbent materials in respirators because of their larger surface area, lighter weight, and fabric form. The purpose of this study was to characterize the breakthrough curves of toluene for different types of commercially available ACFs to understand their potential service lives in respirators. Two forms of ACF, cloth (AC) and felt (AF), with three surface areas each were tested. ACFs were challenged with six toluene concentrations (50-500 p.p.m.) at constant air temperature (23°C), relative humidity (50%), and air flow (16 l min-1) at different bed depths. Breakthrough data were obtained using continuous monitoring by gas chromatography using a gas sampling valve. The ACF specific surface areas were measured by an automatic physisorption analyzer. Results showed unique shapes of breakthrough curves for each ACF form: AC demonstrated a gradual increase in breakthrough concentration, whereas AF showed abrupt increase in concentration from the breakpoint, which was attributed to the difference in fiber density between the forms. AF has steeper breakthrough curves compared with AC with similar specific surface area. AC exhibits higher 10% breakthrough times for a given bed depth due to higher mass per bed depth compared with AF, indicating more adsorption per bed depth with AC. ACF in respirators may be appropriate for use as protection in environments with toluene concentration at the Occupational Safety and Health Administration Permissible Exposure Limit, or during emergency escape for higher toluene concentrations. ACF has shown great potential for application in respiratory protection against toluene and in the development of thinner, lighter, and more efficient respirators.

Carbonation Resistance of Ternary Portland Cements Made with Silica Fume and Limestone.

Ternary blended cements, made with silica fume and limestone, provide significant benefits such as improved compressive strength, chloride penetration resistance, sulfates attack, etc. Furthermore, they could be considered low-carbon cements, and they contribute to reducing the depletion of natural resources in reference to water usage, fossil fuel consumption, and mining. Limestone (10%, 15%, and 20%) with different fineness and coarse silica fume (3%, 5%, and 7%) was used to produce ternary cements. The average size of coarse silica fume used was 238 µm. For the first time, the carbonation resistance of ternary Portland cements made with silica fume and limestone has been assessed. The carbonation resistance was assessed by natural carbonation testing. The presence of coarse silica fume and limestone in the blended cement led to pore refinement of the cement-based materials by the filling effect and the C-S-H gel formation. Accordingly, the carbonation resistance of these new ternary cements was less poor than expected for blended cements.

Facile fabrication of arecanut palm sheath based robust hydrophobic cellulose nanopapers via self-assembly of ZnO nanoflakes and its shelf-life prediction for sustainable packaging applications.

Cellulose nanofibers have been extracted from arecanut palm sheath fibers via mild oxalic acid hydrolysis coupled with steam explosion technique. Cellulose nanofibers with diameter of 20.23 nm were obtained from arecanut palm sheath fibers. A series of robust hydrophobic cellulose nanopapers were fabricated by combining the synergistic effect of surface roughness induced by the successful deposition of zinc oxide (ZnO) nanoflakes and stearic acid modification via a simple and cost-effective method. In this work, agro-waste arecanut palm sheath was employed as a novel source for the extraction of cellulose nanofibers. 2 wt% of ZnO nanoflakes and 1 M concentration of stearic acid were used to fabricate mechanically robust hydrophobic cellulose nanopapers with a water contact angle (WCA) of 134°. During the deposition of zinc oxide nanoflakes on the CNP for inducing surface roughness, a hydrogen bonding interaction is formed between the hydroxyl groups of cellulose nanofibers and the zinc oxide nanoflakes. When this surface roughened CNP was dipped in stearic acid solution. The hydroxyl groups in zinc oxide nanoflakes undergoes esterification reaction with carboxyl groups in stearic acid solution forming an insoluble stearate layer and thus inducing hydrophobicity on CNP. The fabricated hydrophobic cellulose nanopaper displayed a tensile strength of 22.4 MPa and better UV blocking ability which is highly desirable for the sustainable packaging material in the current scenario. Furthermore, the service life of the pristine and modified cellulose nanopapers was predicted using the Arrhenius equation based on the tensile properties obtained during the accelerated ageing studies. The outcome of this study would be broadening the potential applications of hydrophobic and mechanically robust cellulose nanopapers in sustainable packaging applications.

Crack Length of Elastomeric Sealants and Their Service Life in Contrasting Canadian Climates: Effects of Climate Change.

The longevity of polymer-based sealant and jointing products, including elastomers, significantly depends on the level of exposure to sunlight and joint movement. These factors are particularly crucial in the application of polymers in construction due to their susceptibility to degradation under environmental conditions. For instance, diurnal cycles of contraction and dilation, arising from daily temperature fluctuations, impose significant stress on sealants and joints, impacting their durability over time. The elastic nature of polymeric sealants enables them to endure these cyclic mechanical loads. Athough there is considerable information on sealant durability obtained from laboratory accelerated aging, there is limited knowledge about the effect of climatic factors using historical and projected weather data on the durability and expected service life of these products. This study employed the Shephard crack growth model to predict the performance of sealants in a Canadian context; the crack growth and time-to-failure of hypothetical silicone sealants were investigated across 564 locations, for which historical climate data were obtained from 1998 to 2017, including gridded reanalysis data for the period of 1836-2015. The historical climate data were classified into four climate categories, and crack growth was estimated based on historical climatic data within the valid range for the Shephard model, revealing that locations in colder climates with lower levels of precipitation typically exhibit higher cumulative crack growth. The impact of climatic variation and environmental stressors on the longevity of sealants in the context of climate change was also investigated using future projected data.

Long-Service-Life Rigid Polyurethane Foam Fillings for Spent Fuel Transportation Casks.

Soft materials bearing rigid, lightweight, and vibration-dampening properties offer distinct advantages over traditional wooden and metal-based fillings for spent fuel transport casks, due to their low density, tunable structure, excellent mechanical properties, and ease of processing. In this study, a novel type of rigid polyurethane foam is prepared using a conventional polycondensation reaction between isocyanate and hydroxy groups. Moreover, the density and size of the pores in these foams are precisely controlled through simultaneous gas generation. The as-prepared polyurethane exhibits high thermal stability exceeding 185 °C. Lifetime predictions based on thermal testing indicate that these polyurethane foams could last up to over 60 years, which is double the lifetime of conventional materials of about 30 years. Due to their occlusive structure, the mechanical properties of these polymeric materials meet the design standards for spent fuel transport casks, with maximum compression and tensile stresses of 6.89 and 1.37 MPa, respectively, at a testing temperature of -40 °C. In addition, these polymers exhibit effective flame retardancy; combustion ceased within 2 s after removal of the ignition source. All in all, this study provides a simple strategy for preparing rigid polymeric foams, presenting them as promising prospects for application in spent fuel transport casks.