Loss Of Durability Research Articles

Fractal correlation properties of heart rate variability and respiratory frequency as measures of endurance exercise durability.

Field-based measures of durability (exercise-related physiologic deterioration over time) for assessing athletic fitness often rely on changes in maximal power profiles or heart rate (HR) drift. This study aimed to determine whether an index of HR variability based on the short-term exponent of Detrended Fluctuation Analysis (DFA a1) along with respiratory frequency (fB) could demonstrate changes in durability during a Time to Task Failure (TTF) Trial. Ten participants performed a cycling TTF at an intensity of 95% of the respiratory compensation point (RCP) on two occasions, Control and a "Reward" where a monetary incentive was offered when task failure was signaled. Metabolic responses including oxygen uptake ( ), lactate and glucose along with HR, DFA a1 and fB were measured and compared over each quarter of the TTF up to the time of signaling (Q1, Q2, Q3, and Q4). The elapsed time of TTF sessions was statistically similar (p = 0.54). After initial equilibration, metabolic responses remained largely stable over Q2-Q4. HR, DFA a1 and fB displayed drift over Q2-Q4 with significant ANOVA. Repeatability of quarterly HR, DFA a1, and fB between Control and Reward sessions was high with ICC between 0.73 and 0.94, Pearson's r was between 0.83 and 0.98 with no difference in mean values by paired t testing. HR, fB and DFA a1 are useful metrics representing alteration in physiologic characteristics demonstrating durability loss during an endurance exercise session. These measures were repeatable across sessions and have the potential to be monitored retrospectively or in real time in the field with low-cost consumer equipment.

Innovative strategies for designing and constructing efficient fuel cell electrocatalysts.

Polymer electrolyte membrane fuel cells (PEMFCs) are one of the most promising energy conversion devices due to their high efficiency and zero emission; however, two major challenges, high cost and short lifetime, have been hindering the commercialization of fuel cells. Achieving low-Pt or non-precious metal oxygen reduction reaction (ORR) electrocatalysts is one of the main research ideas in this field. In this review, the degradation mechanism of Pt-based catalysts is firstly explained and elucidated, and then five strategies are suggested for the reduction of Pt usage without loss of activity and durability: modulation of metal-support interactions, optimization of local ionomers and mass transport, modulation of composition, modulation of structure, and multi-site synergistic effects. For carbon-based non-precious metal catalysts, the problems and challenges faced by heteroatom/transition-metal doped carbon-based catalysts are discussed, and several strategies to improve the activity of heteroatom/transition-metal doped carbon catalysts are suggested. Particularly, an innovative quantum well catalyst structure reported quite recently is presented which may open up new prospects for the development of fuel cell technology. Finally, this review concludes with a brief conclusion and prospects for future development of low-Pt and non-precious metal fuel cell electrocatalysts.

Relapse-free survival is progressively shortened in a subset of Black patients with immune-mediated TTP treated in the rituximab era.

Immune thrombotic thrombocytopenic purpura (iTTP) is a chronically relapsing disorder caused by autoantibody-mediated deficiency of ADAMTS13. Rituximab is frequently administered to prevent relapses, but whether the durability of rituximab effect is maintained with subsequent treatment courses has not been studied. Using the United States Thrombotic Microangiopathy Consortium (USTMA) retrospective iTTP registry, we evaluated clinical relapse-free survival (RFS) with subsequent courses of rituximab treatment in multiply relapsing patients. Separately, we evaluated overall RFS (composite of time to clinical relapse, ADAMTS13 relapse, or preemptive rituximab) in a prospective iTTP cohort from the Johns Hopkins University and the University of Minnesota. In the USTMA registry, median clinical RFS was shorter after the second or subsequent rituximab-treated episode than the first (2.1 vs 6.0 years; P=.04). White patients' clinical relapse risk after the second and subsequent rituximab courses was not significantly different compared with the first (hazard ratio [HR], 1.86; 95% confidence interval [CI], 0.22-15.80; P=.57), whereas for Black patients, clinical relapse risk was significantly higher after the second or subsequent courses (HR, 2.82; 95%CI, 1.52-5.24; P=.001). In the prospective cohort, overall RFS progressively shortened after each episode of rituximab treatment with the first episode having the longest RFS (2.8 years; interquartile range, 2.0-6.0) and this loss of response durability was most pronounced in Black patients. The durability of rituximab's effect declines with subsequent treatments, which is more pronounced in Black patients, who may benefit from closer monitoring and alternative immunomodulatory approaches such as maintenance rituximab and consideration of other agents.

Iridium Thrifting and Circularity: Perspective, Progress, and Demonstration from an OEM

Proton exchange membrane water electrolysis (PEMWE) is a technology that has promise to help decarbonize the hydrogen sector and thus has recently been receiving significant attention. Incentives across the globe, including in the Hydrogen Hubs in the US and the European Hydrogen Bank, have been announced to support early projects and catalyze the industry. The PEMWE market growth was already starting due to recent technological advances and these incentives are helping further accelerate the industry. This acceleration is evident by the number of press releases on manufacturing capacity expansion and large projects being announced. With this market expansion, the industry will inherently demand more iridium – currently the only commercially viable OER catalyst for PEMWE. The mantra of reduce, reuse, and recycle is being applied to iridium where iridium thrifting (reduce) and circularity (recycle) are focal points.The first part of this talk will focus on iridium thrifting. Simply reducing the catalyst loading with today’s baseline technology results in performance and durability loss; therefore, advanced materials and technology must be developed to realize the iridium thrifting goals. Performance and durability data will be presented for state-of-the-art catalyst that enable low iridium loadings. The second part of this talk will cover iridium circularity. Various recycling streams exist including manufacturing waste, manufacturing scrap, and end-of-use devices from the field. The value recovery for each of these waste streams will be discussed and data demonstrating full circularity will be presented.

Insight into the Modification of the Low-Pt Electrocatalysts By the Defective Metal Oxide Additives: The Effect on the Oxygen Reduction Reaction in Acid Media

The global rise in energy consumption combined with severe environmental issues and climate change has promoted the development of green alternative technologies such as low-temperature proton exchange membrane fuel cells (PEMFCs). However, the performance and operational cost of PEMFC largely depend on the application of highly expensive state-of-the-art Pt-based systems, which are so far the most effective catalysts for the oxygen reduction reaction (ORR) at the fuel cell’s cathode. The widespread commercialization of the PEMFC technology has also been complicated by the limited lifetime of catalytic systems due to the instability of carbon supports as well as Pt catalytic centers. Due to these facts, it is of great significance to gain an in-depth insight into the ORR mechanism to optimize the activity of the ORR catalytic centers and their more efficient utilization while minimizing the Pt content without loss of performance and durability, which are essential features to ensure wider use of the low-temperature hydrogen-oxygen fuel cell systems. One of the reasonable strategies for ameliorating stability, and selectivity of carbon-supported low Pt content electrocatalysts for the ORR in acid media is their functionalization by selected nanostructured non-noble metal oxides (MOx)1. The strong mutual interactions between all components in such hybrid material (Pt, C, MOx) are capable of tuning the Pt electronic structure at the electrocatalytic interface, thus promoting centers for the adsorption of oxygen and the cleavage of O=O bonds as well as the durability of the carbon carriers can be improved under highly aggressive acidic conditions. Additionally, the application of metal oxide co-catalysts which are capable of inducing the decomposition of hydrogen peroxide and/or scavenging of free radicals can make a significant contribution to improving the durability and overall efficiency of fuel cells.Due to the unique structure, redox ability, oxygen vacancies, and other features resulting from the 4f electronic configuration of cerium, in the present studies, we synthesis the reduced CeOx nanostructured and investigate the influence of such additive on the stability and selectivity of low-Pt content electrocatalysts in the oxygen reduction reaction (ORR) in acidic media. The stable oxide phases with the tailored redox properties and the presence of oxygen vacancies were obtained by controlling their morphology and composition. Preparation of small ceria nanoparticles by microwave-assisted hydrothermal method and introduction of various dopants (e.g. Pr, Nb, Cu) into these oxide structures improve its reducibility and non-stoichiometry phase content, optimizing important parameters for catalytic activity. The received results revealed that the CeOx/M-CeOx additive is allowed to obtain a lower amount of undesirable H2O2 produced during the ORR and improve the Pt/C stability. It is assumed that the improved durability and the better selectivity towards 4e– reduction of oxygen of the modified catalyst result from the defective cerium oxide properties and strong interactions between all components. Acknowledgments: This research was funded by the National Science Center (Poland) under Sonatina Project (2022/44/C/ST5/00077) and under the auspices of the European Union EIT Raw Materials ALPE 19247 Project (Specific Grant Agreement No. EIT/RAW MATERIALS/SGA2020/1).

Study on the influence of early frost attack on the performance of cement mortar

The loss of strength and durability caused by early frost attack is the macro performance of internal microstructure deterioration. Understanding the influence mechanism of early frost attack at the micro level is necessary to avoid or minimize the early frost attack to macro performance. In this study, the influence of early frost attack on the strength, water sorptivity, chloride permeability, and microstructure of cement mortar was investigated. The fresh mortars were pre-cured for 10, 12, 14, and 16 h and then frozen at −10 °C for 7 days to simulate an early frost attack. After freezing, the standard curing (20 °C) was carried out until the testing. It is found that after standard curing of 28 days, the strength of early-frozen mortar can reach more than 95 % of the 28-day strength of unfrozen mortar. Interestingly, the sorptivity coefficient and total charge passed of early-frozen mortar are much higher than the level of unfrozen mortar, and the loss of resistance to water penetration and chloride ion penetration exceeds 20 %, indicating that early frost attack causes more severe damage to the durability than to the strength of mortar. Mercury intrusion porosimetry (MIP) results show that early frost attack can increase the pore volume of >50 nm and coarsen the pores within 10–50 nm. Correspondingly, key pore parameters (critical pore diameter, threshold pore diameter, and tortuosity) that affect the durability of mortar are also negatively affected. Energy dispersive spectroscopy (EDS) analysis also shows that after suffering early frost attack, the interfacial transition zone (ITZ) thickness of mortar is increased from 4 to 10 μm to 8–13 μm, and the probability of high Ca/Si ratios (4–10) in the ITZ is also increased. Finally, it is concluded that the coupling effect of pore structure coarsening and ITZ degradation leads to more severe durability loss.

Moisture Sensitivity of Hot Mix Asphalt Modified with Micronized Calcium Carbonate

Moisture sensitivity in an HMA refers to the loss of mastic cohesion and durability between the bitumen and aggregates due to water presence. Various methods exist to mitigate this type of sensitivity, with one of the most important approaches being the incorporation of anti-stripping agents into either the bitumen or aggregate materials. Based on this premise, the current study investigates the impact of using micronized calcium carbonate powder (MCCP or CaCo3) as a modifier for bitumen on moisture sensitivity in HMA. Three types of aggregates with different mineralogical properties (limestone, granite, and quartzite), and PG 64–16 bitumen (along with 2% and 4% MCCP based on the mass of the bitumen) were utilized. The modified Lottman test was performed under 1 to 5 freeze-thaw cycles while measuring surface free energy (SFE) elements for both bitumens and aggregates with Wilhelmy Plate (WP) and Universal Sorption Device (USD), respectively. The results of the moisture sensitivity test on the asphalt mixtures used in this study demonstrate that the addition of MCCP in the modified samples has led to a reduction in the sensitivity of the asphalt mixtures, particularly in multiple freeze-thaw cycles, compared to the control samples. Furthermore, findings from SFE analysis demonstrated that MCCP enhanced cohesion free energy (CFE) which subsequently reduced rupture probability within the bitumen membrane. Additionally, it improved adhesion between acidic aggregates susceptible to moisture-induced sensitivity and bitumens.

A study on estimating deterioration in multi recycled aggregate concrete using surface imaging techniques

The study presents a novel method for sustainable construction using multi-recycled concrete, embracing a cradle-to-cradle approach. It utilies image analysis to detect concrete deterioration due to different chemical exposures. It also demonstrates the effectiveness of the Compressible Packing Method in improving recycled aggregate properties and reducing cement content for sustainable concrete production. The image-based colour stability analysis for determining Hue (H), Saturation (S), and Intensity (I) values reveals the significant deterioration is caused by sulphuric acid and hydrochloric acid exposures relevant to field applications. A unified factor termed as Durability Loss Factor (DLF) provides a comprehensive metric for assessing deterioration, with sulphuric acid exposure resulting in the most substantial deterioration. Also, there is a strong correlation between residual strength of concrete specimen and the parameters governing image analysis in the current study. These findings offer valuable insights into mix design strategies, colour-based indicators of deterioration, and the development of a comprehensive Durability Loss Factor for multi-recycled concrete.

ANALYSIS OF UNCONTROLLED WEAR IN THE AREA OFA BELLEVILLE SPRING OF A FRICTION TORSIONAL VIBRATIONDAMPER IN A MOTOR VEHICLE CLUTCH

The article describes the problem of excessive tribological wear of a torsional vibration damper built intoa single-disc friction clutch of a truck vehicle. In contrast to the controlled, design-based wear of damper’sfriction rings, i.e., wear whose kinetics are known and predictable, uncontrolled wear at Belleville springcontact surfaces effects in a premature decrease in the damper’s friction torque and, consequently, loss ofdurability. As a result of the analyses and experimental work, the causes of accelerated wear were identified.Sets of springs and friction rings from the 10 used vibration dampers that worked under similar operatingconditions but with different operating periods were used as the basic research material. The influence ofabrasive wear of Belleville springs on their load-deflection characteristic was identified. A comparativeanalysis of the characteristics of the new spring and the used springs is also presented to illustrate changes inthe axial load in the assemblies of the analyzed dampers.

Contemporary experience of mitral transcatheter edge-to-edge repair technology in patients with mitral annular calcification.

Mitral annular calcification (MAC) has been an exclusion for many of the earlier pivotal trials that were instrumental in gaining device approval and indications for mitral transcatheter edge-to-edge repair (M-TEER). To evaluate the impact of MAC on the procedural durability and success of newer generation MitraClip® systems (G3 and G4 systems). Data were collected from Northwell TEER registry. Patients that underwent M-TEER with third or fourth generation MitraClip device were included. Patients were divided into -MAC (none-mild) and +MAC (moderate-severe) groups. Procedural success was defined as ≤ grade 2 + mitral regurgitation (MR) postprocedure, and durability was defined as ≤ grade 2 + MR retention at 1 month and 1 year. Univariate analysis compared outcomes between groups. Of 260 M-TEER patients, 160 were -MAC and 100 were +MAC. Procedural success was comparable; however, there were three patients who required conversion to cardiac surgery during the index hospitalization in the +MAC group versus none in the -MAC group (though this was not statistically significant). At 1-month follow-up, there were no significant differences in MR severity. At 1-year follow-up, +MAC had higher moderate-severe MR (22.1% vs. 7.5%; p = 0.002) and higher mean transmitral gradients (5.3 vs. 4.0 mmHg; p = 0.001) with no differences in mortality, New York Heart Association functional class or ejection fraction. In selective patients with high burden of MAC, contemporary M-TEER is safe, and procedural success is similar to patients with none-mild MAC. However, a loss of procedural durability was seen in +MAC group at 1-year follow-up. Further studies with longer follow-ups are required to assess newer mTEER devices and their potential clinical implications in patients with a high burden of MAC.

Improvement of crack detectivity for noisy concrete surface by machine learning methods and infrared images

In order to maintain serviceability and reliability of concrete structures, it is essential to assess their condition as concrete structures deteriorate in time. Cracks develop in concrete due to several reasons such as severe loading, environmental effects, chemical effects etc. and cause durability loss in the structure which may also lead to loss of stability. In this research, crack detection is realized by machine learning and an infrared image. The effects of infrared images on crack detection are confirmed by random forest algorithm to select useful explanatory features. Selected features are applied to random forest algorithm and neural network algorithm. Effective filters are selected as a feature selection technique to improve the accuracy. Crack detection is also conducted by U-Net with RGB and infrared images, and the detection characteristics are compared to conventional methods. The performance of two conventional machine learning methods, random forest and neural network, are evaluated based on F1 score and false positives. Applying selected features improves the accuracy of the crack detection from an infrared image. False positives decreased due to monitoring conditions and camera specifications in the infrared image. The most effective image processing filter is the blur filter for each algorithm. Comparing algorithms for crack detection using selected features, different accuracy values are obtained. U-Net enables more accurate crack detection compared to conventional methods. The number of false positives is reduced compare to conventional method. In the detection results by three algorithms, infrared image affects the balance of false negatives and false positives.

(Invited) Enhancement of Activity of Low-Pt-Content-Catalysts Toward Oxygen Reduction through Admixing with Metal Oxide Cocatalysts

The proton-exchange membrane fuel cell (PEMFC) technology is one of the most promising approaches for energy conversion in automotive applications. Despite the use of expensive noble metal electrocatalysts, the sluggish kinetics of the oxygen reduction reaction (ORR) in acid media, and formation of the undesirable hydrogen peroxide intermediate are still the main drawbacks, on top of the stability problems, when it comes to the widespread commercialization of PEMFC devices. The progress in this subject is greatly hindered by the high cost and scarcity of the state-of-the-art platinum-based materials which are regarded as the most effective cathode catalysts. Therefore, most of the current research studies have been devoted to the optimization of active centers and maximization of their utilization, which should allow the lowering of the cathode Pt loadings without loss of performance and durability. Unfortunately, the problem of electrochemical stability and the danger of generation of higher quantities of the undesirable hydrogen peroxide intermediate may become even more serious in the case of systems utilizing lower amounts of the Pt catalystAmong important strategies is hybridization, activation, and stabilization of carbon-supported Pt catalysts by functionalization through admixing with certain nanostructured and typically substoichiometric metal oxides. Special attention is paid to application of the bi- or multi-metallic Pt-based alloys in their various forms and structures. Additionally, doping of carbon carriers with heteroatoms would produce surface functional groups and active centers capable of not only improving the catalysts’ performance, but also affecting their stability. Among other important issues are such features as porosity, hydrophilicity, and degree of graphitization of carbon components, in addition to the existence of metal–support interactions, high electrochemical active surface area, electronic structure of interfacial Pt, and the feasibility of adsorptive or activating interactions with oxygen molecules.Platinum is a main catalyst for the electroreduction of oxygen, the reaction of primary importance to the technology of low-temperature fuel cells. Because of high cost of platinum. there is a need to significantly lower its loadings at interfaces. But then O2-reduction proceeds often at less positive potentials and produces higher amounts of undesirable H2O2-intermediate. Hybrid supports, which utilize metal oxides (e.g., CeO2, WO3, Ta2O5, Nb2O5, ZrO2), stabilize Pt and carbon nanostructures, diminish their corrosion while exhibiting high activity toward the four-electron (most efficient) reduction of oxygen. Porosity of carbon supports facilitates dispersion and stability of Pt nanoparticles. The catalytic efficiency depends on geometric (decrease of Pt–Pt bond distances) and electronic (increase of d-electron vacancy in Pt) factors, in addition to possible metal-support interactions and interfacial structural changes affecting adsorption and activation of O2-molecule.

Mechanical Performance of Cementitious Materials Reinforced with Polyethylene Fibers and Carbon Nanotubes

The cracking of cementitious materials due to their quasi-brittle behavior is a major concern leading to a loss in strength and durability. To limit crack growth, researchers have incorporated microfibers in concrete mixes. The objective of this study is to determine if nano-reinforcements can arrest cracks and enhance the material performance in comparison to microfibers. A total of 28 specimens were prepared to investigate and compare the effects of incorporating carbon nanotubes (CNTs) as a nano-reinforcement and polyethylene (PE) fibers at a macro-level and their combination. Compressive and flexural strengths were experimentally tested to assess the mechanical performance. The microstructure of the mortar samples was also examined using a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). The ductility increased by almost 50% upon the addition of CNTs, while no significant enhancement was witnessed for the compressive strength. The flexural strength increased by 169% and the flexural strain by 389% through the addition of the combination of CNTs and PE fibers.

PRODUCTION OF SELF-HEALING MORTAR USING BACTERIAL SPORES ENCAPSULATED WITH JUTE FIBRE

Cement-based composites have various advantages such as low cost, easy shaping, and high compressive strength. Therefore, they are widely used in the construction industry. However, their brittle structure makes them prone to cracking, which must be repaired promptly to avoid possible loss of strength and durability and ultimate structural failures. Microbially-induced calcite precipitation (MICP) offers an effective method for healing these cracks. Unlike other treatments, MICP method is a natural and environment-friendly option for self-healing of cracks. However, bacteria can be damaged by cement and mechanical impacts; therefore, encapsulation is necessary to protect them. Encapsulation in fibres is a simpler and more cost-effective method than the other techniques. This study tested the effectiveness of encapsulating Bacillus megaterium spores in jute fibres and added them to cement-based mortars. Different nutrient supplements were used, and physical analyses and compressive strength tests were conducted on 28-day cured cube specimens. Present findings revealed that Bacillus megaterium-type bacteria encapsulated in jute fibres improved the compressive strength recovery and healed the loading-induced cracks.

Response Duration and Relapse Free Survival Shorten after Each Episode of Immune Thrombotic Thrombocytopenic Purpura (iTTP) Treated in the Rituximab Era

INTRODUCTION: Immune thrombotic thrombocytopenic purpura (iTTP) is caused by an autoantibody mediated deficiency of ADAMTS13 and characterized by recurrent episodes of life-threatening thrombotic microangiopathy. Rituximab (anti-CD20 monoclonal antibody) reduces relapse rates in many cases. This multicenter observational aimed at comparing durability of rituximab response (measured as relapse free survival, RFS) in first versus subsequent episodes of iTTP based on the clinical observation that patients with multiply relapsing disease may have attenuated responses to rituximab. METHODS: We first evaluated clinical RFS (time from rituximab treatment to clinical relapse) in the United States Thrombotic Microangiopathy Consortium retrospective iTTP registry that includes data from 15 high volume academic centers. We performed a subsequent analysis from the well-phenotyped Johns Hopkins University (JHU) and University of Minnesota (UM) prospective iTTP cohorts, that additionally include serial assessments of ADAMTS13 activity in remission, to confirm our findings and to evaluate overall RFS [a composite of clinical relapse, ADAMTS13 relapse including ADAMTS13 relapse treated with preemptive rituximab) which is a clinically relevant endpoint in the era of ADAMTS13 monitoring and receiving preemptive rituximab. ADAMTS13 relapse was defined as ADAMTS13 <20% without thrombocytopenia or symptoms. In both analyses, we included only patients with > 1 year follow up after treatment with rituximab (either during iTTP episodes or preemptive) and excluded those who received immunosuppression other than rituximab or steroids. Patients who started maintenance rituximab (every 3 or 6 months) were censored at that point). We used Cox regression to examine factors associated with clinical RFS and overall RFS including first versus subsequent rituximab treatment episodes as a covariate, and Kaplan-Meier survival curves to visualize these relationships. RESULTS: In the USTMA registry, 310 unique patients had a total of 384 iTTP episodes treated with rituximab (310 first, 53 second, and 21 were 3rd to 5th courses of rituximab) between 2003-2019. Presenting in relapsed iTTP [HR 2.10 (95% CI 1.24 - 3.58)], Black race [HR 3.12 (95% CI 1.68-5.80)] and second or subsequent rituximab course [HR 2.80 (95% CI 1.53-5.10)] were associated with clinical relapse in a Cox regression model that also included age, sex, and exacerbations. Median RFS was higher after the first compared with subsequent (2nd-5th) rituximab courses (6.0 vs 2.1 years, P = 0.04). Since race was significantly associated with clinical RFS in the Cox regression model, we evaluated clinical RFS after first and subsequent rituximab courses separately for Black and White participants. Among White patients, clinical RFS after the second or subsequent rituximab courses was not significantly different compared to the first course [HR=1.86 (95% CI 0.22-15.80), P=0.57]. However, in Black patients, clinical RFS was shorter after the second and subsequent rituximab courses [HR=2.82 (95% CI 1.52-5.24), P=0.001]. The JHU and UM cohort included 97 patients with 266 episodes of rituximab treatment. Similar to the USTMA cohort, median clinical RFS was shortened with reach subsequent rituximab course. Median overall RFS (time to clinical or ADAMTS13 relapse) was also longest after the first rituximab course [2.8 (IQR 2.0-6.0) years] followed by the second course [2.0 (IQR 1.2-3.6) years], and third and subsequent episodes courses [1.0 (IQR 0.5-2.5) years] (P< 0.001). Overall RFS was shorter in White patients and the loss of response durability with later courses was most prominent in Black versus patients. For examples, median overall RFS from the first to the third or later courses reduced from 3.6 years to 1.5 years for White patients, and from 2.7 years and 0.9 years in Black patients (Figure 1). CONCLUSIONS: Despite's rituximab's known effect of prolonging RFS in iTTP, the time to clinical relapse or ADAMTS13 relapse (often a precursor of clinical relapse) shortens with multiple episodes/treatment courses with an earlier ‘wearing off’ effect in Black patients especially those being treated in relapse. Patients who have had ≥ 2 rituximab courses may need closer monitoring and and consideration of maintenance rituximab or other immunomodulators.

Physicomechanical Properties of Carbon Nanotubes Reinforced Cementitious Concrete – A Review

Though concrete is one of the most widely used construction materials, there are some concerns and shortcomings associated with it. Cementitious materials' quasi-brittle behavior, which leads to cracking and a loss of durability, is a major concern in structural applications. In this review, the latest research on reinforcing cementitious concrete with carbon nanotubes (CNTs) is reviewed, with an emphasis on the material's structural performance in building and a comparison of CNTs to other reinforcing fibers. The improvement of the macro mechanical properties of carbon nanotube-reinforced composite structures has been discussed in the form of functionally graded carbon nanotubes reinforced composites (FG-CNTRC). Several researches have, in the past, used other forms of reinforcements to enhance the properties of concrete till the implementation of nanotechnology in concrete production by incorporating CNTs into the concrete mixes. Concrete's crucial mechanical properties as a structural material and the durability of conventional cement-based building materials can both be improved by CNTs. They have drawn a lot of interest because they are an engineering material with a wide range of uses. The creation and characterization of cement-based materials reinforced with CNTs have been studied by researchers. Comparisons between the effects of CNT and other fibers on concrete have also been made. This concrete reinforcement type's environmental impact and sustainability have also been discussed. According to studies, CNT can greatly enhance the performance of cement-based materials.

Degradation mechanisms in overpack concrete of spent nuclear fuel dry storage systems: A review

Dry storage systems are successfully used for interim storage of commercial spent nuclear fuel (SNF). Many of these systems consist of sealed, welded canisters placed inside concrete storage modules. Associated with the need for extending the operational periods of some of these systems, there are concerns that their concrete overpacks could degrade over time. This could lead to a loss of strength and durability. Potential degradation mechanisms include chemical attacks, concrete cancer, or freeze–thaw (F-T) cycles, making them prone to failure during extended periods of dry storage, especially when stressed during a hazardous event, such as an earthquake. The concrete mixtures that have been used in dry storage systems have not changed significantly since their introduction, and available mixtures often have the same ingredients used in conventional concrete. With the latest evolutions in material science, new concrete composites with ultra-high strength and outstanding thermal and mechanical properties can be utilized in such structures. Within a collaboration between the University of Idaho and the Idaho National Laboratory, enabled by funding provided by the Center of Advanced Energy Systems (CAES), a thorough review of SNF dry storage system overpack degradation observations were conducted. Further, the latest technologies in concrete composite materials with extraordinary strength, outstanding durability were identified. This paper presents and summarizes the most relevant mechanism of concrete deterioration in SNF systems, and identifies new materials to be used in future concrete mixtures to increase the service life of SNF dry storage systems and to lengthen inspection intervals.

The use of low alkalinity MgO-SiO2 formulation to encapsulate bacteria for self-healing concrete

Concrete structures are inherently brittle, rendering them susceptible to cracking, which in turn allows moisture, carbon dioxide, and harmful ions to penetrate, ultimately resulting in a loss of durability and strength. Incorporating encapsulated or immobilized bacteria in concrete has proven to be an effective way to promote the self-healing of cracks. However, the commonly used bacteria-based capsules and carriers tend to significantly reduce the matrix strength. To address the strength reduction while facilitating self-healing, the present study proposes utilizing the MgO-SiO2 formulation, a low alkalinity cementitious system, for encapsulating bacteria in self-healing concrete. Results showed that the incorporation of the capsule can maintain the strength of a cement paste. Furthermore, the addition of the capsule to the PC paste can engage effective self-healing. Cracks between 250 and 350 µm can reach 97% closure while cracks between 350 and 600 µm can reach 85% of closure, and the water passing through the crack reduced around 80% after 40 wet/dry conditioning cycles. Besides, the capsule possessed long-term stability where the concentration of viable bacteria remained stable in the capsule.

Atomic layers of ruthenium oxide coupled with Mo2TiC2Tx MXene for exceptionally high catalytic activity toward water oxidation

Progress in acidic water splitting has remained limited because of low oxygen evolution reaction (OER) activities, sluggish reaction kinetics, and severe catalyst degradation. Thus, a highly active and durable OER catalyst is required for the commercialization of acidic water electrolyzers. Here, we report t-phase ruthenium oxide atomic layers implanted on Mo2TiC2Tx MXene (RAL-M) as a model electrocatalyst for the OER in acidic media, which exhibits a remarkable mass activity (6.2 A mg−1), excellent turnover frequency (TOF; 2.4 s−1), and negligible loss of durability after 22 h in a two-electrode cell configuration. The mass activity and TOF of RAL-M are 150 times (RuO2-Premetek Co.) and 540 times (RuO2-Sigma-Aldrich) greater than the industrially adopted electrocatalysts at pH 0.48. Computational calculations show that the ruthenium active sites of RAL-M have a strong affinity to oxygen species (e.g., OH*, O*, and OOH*), which efficiently adapts water dissociation and favors both the adsorbate evolution and lattice oxygen mechanistic pathways to accelerate the OER.

Enhancing durability of polymer electrolyte membrane using cation size selective agents

Radical species generated during proton exchange membrane fuel cell operation considerably limit the achievable durability, particularly for heavy-duty vehicle applications. A promising solution to the problem is the incorporation of radical scavenger additives such as cerium which mitigates chemical attacks on the membrane. However, these additives migrate during fuel cell operation causing a loss in durability and performance due to detrimental interaction with various components of the fuel cell. Here, we study cation size selective agents as a means to immobilize cerium within perfluorosulfonic acid (PFSA) membranes. We synthesized an organometallic complex of cerium with 15-Crown-5 and investigated the effectiveness of this complex to immobilize cerium. Over 300% increase in cerium retention and an 80% increase in chemical durability were observed owing to the stabilization effect of crown ethers on cerium. Migration under a potential gradient can be eliminated while the complex also contributes to the enhancement in cerium radical scavenging activity. Current challenges with the proposed solution are highlighted and future work is discussed.