Cumulative Mass Loss Research Articles

Influence of particle lithology, size and angularity on rates and products of bedload wear: An experimental study

AbstractPhysical wear during bedload transport influences downstream changes in the size distributions and shapes of riverbed sediment, which in turn affect myriad fluvial processes ranging from incision into bedrock to provision of aquatic habitat. Here we use laboratory tumbling experiments to address several remaining knowledge gaps, including the roles of lithologic susceptibility to fragmentation, particle size distributions and particle angularity in controlling wear rates and the size distribution of wear products. To focus on the dynamics of particle wear in headwater channels, we used initially angular sediment and ran the experiments until 10% of the initial bedload particle mass had been lost to fine‐grained wear products. We measured individual particle mass and diameter by hand and used photo analysis to quantify particle shape and angularity. We find strikingly different wear patterns between limestone and welded tuff. Although wear rates in the tuff were an order of magnitude slower than the limestone, tuff wear was primarily by fragmentation while limestone wear was dominantly by attrition. Fragmentation of the tuff resulted in a widening of the bedload size distribution, a lack of consistent particle rounding and a fine‐wear product dominated by sand. In contrast, limestone particles rounded substantially and produced silt‐sized wear products. Differences in wear product size and susceptibility to fragmentation may reflect contrasts in the size distribution of mineral crystals in each lithology. Wear rates in both rock types declined substantially with increasing cumulative mass loss, due to rounding in the limestone and reduced fragmentation in the tuff. These results suggest that applications of the conventional exponential model to predict mass loss with travel distance need to account for lithologic influence on susceptibility to fragmentation and the influence of rounding on particle wear rates.

Comparison of volatiles evolving from selected highland and mare lunar regolith simulants during vacuum sintering

Volatiles evolving from JSC-1A, NU-LHT-4M and CSM-LHT-1G lunar regolith simulants during in vacuo thermal processing were analyzed using mass spectrometry as a function of temperature. Two high-fidelity simulants, JSC-1A (mare) and NU-LHT-4M (highland), were compared to a newly developed CSM-LHT-1G highland simulant, modified to closely match lunar geochemistry. Large autogenous gas loads were observed for all investigated materials. Mineralogical knowledge was used to identify and attribute individual volatile species to reacting, transforming, or decomposing constituents (hydrates, carbonates, sulfates, sulfides, clays, etc.) of the respective regolith simulant in the self-generated gas environment. Cumulative mass losses for individual simulant components as a function of temperature were quantified using mass spectrometry in conjunction with thermogravimetric analysis. Investigation of the four components of CSM-LHT-1G – anorthosite, basalt, augite, and glass – aided the attribution of volatile species to specific compounds and their respective sources. The results showed significant decomposition of non-lunar phases present in the man-made regolith simulants below the typical glass crystallization temperatures, which paves the way to devising methods for enhancing the fidelity of the simulants. High gas loads and corrosive gases (HF and HCl) were recognized as potential hazards, pertaining to the development of large testbed facilities.

Fracture toughness and cavitation erosion behavior of Fe-based amorphous composite coatings with Ni-coated Al2O3 addition

Fe-based amorphous composite coatings were prepared on 304 stainless steel substrates using atmosphere plasma spraying (APS), aiming to investigate the effect of Ni-coated Al2O3 particles addition on fracture toughness and cavitation erosion behavior of Fe-based composite coatings. The microstructure, phase composition, elastic modulus, microhardness and fracture toughness of the coating were characterized using scanning electron microscopy with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), microhardness tester and nanoindentation. The cavitation erosion behavior of Fe-based coatings was investigated by ultrasonic vibration cavitation method. Fe-based amorphous composite coatings exhibit a characteristic lamellar microstructure and reveal the presence of amorphous phases along with α-(Fe, Cr), NiO, Ni and Al2O3 crystalline phases. When the content of Ni-coated Al2O3 in coating increases from 0 wt% to 3 wt%, there is slight deterioration in porosity from 3.64 % to 4.75 % and fracture toughness from 2.579 MPa·m1/2 to 2.392 MPa·m1/2, yet an increase in microhardness from 925.4 HV0.5 to 1090.3 HV0.5. The composite coating with 3 wt% Ni-coated Al2O3 demonstrates the peak cavitation resistance and its cumulative mass loss is significantly reduced by 36.4 % compared to the pure Fe-based coating. The cavitation erosion failure of Fe-based amorphous composite coatings is predominantly characterized by the brittle fracture mechanism. The fundamental process driving cavitation erosion damage involves the material peeling and coating delamination instigated by intense micro-jet impact and shock wave propagation. The proposed Fe-based amorphous composite coatings can be applied to improve the anti-cavitation performance of components in contact with high-speed fluids, such as ship propellers and centrifugal pump blades.

Developing Online ICP-MS Methodology for Examining Catalyst Degradation Dynamics during Electrochemical CO2 Reduction

The electrochemical CO2 reduction reaction (CO2RR) provides a path towards sustainable production of carbon-based fuels and chemicals, using renewable electricity to drive the conversion of CO2 into products such as ethylene, ethanol, and methane. A challenge limiting the implementation of CO2RR is catalyst stability during operation, and greater fundamental understanding is needed to uncover the governing physical, chemical, and electrochemical factors, as well as degradation mechanisms, operative under reducing conditions. One tool that can be used for conducting such fundamental studies is online inductively coupled plasma mass spectrometry (ICP-MS). In this study, an experimental framework was developed for using online ICP-MS for time-resolved degradation studies during CO2RR conditions. Using a customized flow cell setup, we coupled an ICP-MS to a potentiostat to simultaneously apply a potential or current while evaluating dynamics and degradation for both Au and Cu catalysts. Both ionic dissolution and degradation in the form of nanoparticle detachment can be detected and analyzed. The presence of nanoparticles is indicated by spikes in ICP-MS data. The intensity of the spikes is directly related to particle size. We used ICP-MS to determine particle mass, size distribution, and cumulative mass loss over time. We found the use of ICP-MS to obtain particle size distribution gave comparable results to transmission electron microscopy (TEM) determination of particle size distribution.Au foil as the CO2 reduction catalyst was used as a model system for detecting and quantifying degradation in situ using ICP-MS. We found Au degradation to occur in the form of nanoparticle detachment, with increasingly negative applied potential (0 V vs RHE to -1 V vs. RHE) in the presence of CO2 leading to increased number of nanoparticles in the electrolyte; however, no ionic dissolution was observed. In comparison, when the electrolyte was saturated with N2, nanoparticles detached from the electrode at a lower rate than in CO2-saturated conditions. We also examined Cu degradation under the same conditions as the Au system. Cu degradation occurs as both ionic dissolution and nanoparticle detachment, but under all conditions, Cu has less nanoparticle detachment and cumulative mass loss due to nanoparticles than Au. The developed experimental framework in this study would be translatable to a variety of electrocatalytic reactions and environments. Examination of catalyst degradation behavior in situ, including non-traditional degradation mechanisms such as nanoparticle detachment from bulk materials, can be used to obtain greater fundamental understanding of degradation mechanisms and rational design of materials with improved stability.

Cavitation erosion-corrosion properties of as-cast TC4 and LPBF TC4 in 0.6 mol/L NaCl solution: A comparison investigation

In this work study, a comparative analysis was undertaken to investigate investigation into the cavitation erosion (CE) and corrosion behavior of laser powder bed fusion (LPBF) TC4 and as-cast TC4 in 0.6 mol/L NaCl solution. Relevant results indicated that LPBF TC4 revealed a rectangular checkerboard-like pattern with a more refined grain size compared to as-cast TC4. Meanwhile, LPBF TC4 surpassed its as-cast counterpart in CE resistance, demonstrating approximately 2.25 times lower cumulative mass loss after 8 h CE. The corrosion potential under alternating CE and quiescence conditions demonstrated that both LPBF TC4 and as-cast TC4 underwent a rapid potential decrease at the initial stages of CE, while a consistent negative shift in corrosion potential was observed with the continuously increasing CE time, indicative of a gradual decline in repassivation ability. The initial surge in corrosion potential during the early CE stages was primarily attributed to accelerated oxygen transfer. As CE progressed, the significant reduction in corrosion potential for both LPBF TC4 and as-cast TC4 was attributed to the breakdown of the passive film. The refined and uniform microstructure in LPBF TC4 effectively suppresses both crack formation and propagation, underscoring the potential of LPBF technology in enhancing the CE resistance of titanium alloys. This work can provide important insights into developing high-quality, reliable, and sustainable CE-resistant materials via LPBF technology.

Exceptional combination of mechanical properties and cavitation erosion-corrosion resistance in a Fe23.7Co23.8Ni23.8Cr23.7Mo5 multi-principal element alloy

This study analyzed cavitation erosion (CE) and cavitation erosion-corrosion (CE-C) of single-phase face-centered cubic structured Fe23.7Co23.8Ni23.8Cr23.7Mo5 multi-principal element alloy (MPEA) with varying grain sizes obtained through post-deformation annealing (PDA). The average grain sizes of the samples after annealing at 1100 °C for 60 s, 1150 °C for 60 s, and 1100 °C for 200 s are 4.1 µm, 10.3 µm, and 15.2 µm, respectively. Among them, the 4.1 µm sample exhibits the best combination of high ultimate tensile strength (889 MPa) and large elongation (40.3%), as well as good electrochemical corrosion resistance in NaCl solution. Under the conditions of CE and CE-C for a duration of 10 h, the 4.1 µm specimen exhibits cumulative mass losses of approximately 1.4 mg and 2.6 mg, respectively. In contrast, under identical conditions, the 316 L SS registers cumulative mass losses of approximately 16.7 mg and 24.8 mg, respectively. Due to the excellent mechanical properties and work hardening ability of the 4.1 µm sample, it can effectively resist the plastic deformation caused by cavitation erosion, reducing mass loss. In addition, the stable passivation film enhances its resistance to Cl- destruction, thus demonstrating notable corrosion resistance. Ultimately, under conditions where cavitation erosion and corrosion coexist, these combined properties enable the 4.1 µm sample to exhibit the least mass loss and damage.

Utilization of Alkali-Activated Rice Husk Ash for Sustainable Peat Stabilization

Abstract Peat is formed from organic matter (OM) in wetlands under an anaerobic environment. Peat is considered weak and problematic soil because of high-water retaining capability, high compressibility, and low shear strength. The cement is generally used to stabilize peat, but cement production is energy intensive and contributes 7–8 % of total carbon dioxide to the atmosphere. Nowadays, there is a need to use a potential “greener” alternative that is sustainable in the long term. Therefore, this research assesses the feasibility of rice husk ash (RHA)–based alkali-activated binder (AAB)–stabilized peat with varying fiber content (6–73 %) and OM (21–79 %). The RHA-based AAB was prepared by adding bauxite powder (as alumina source) to RHA in proportion to keep constant silica to alumina ratio (silica/alumina = 3). The samples were prepared using sodium hydroxide (NaOH) of molarities 3, 6, and 9 to activate the binder with percentages 10, 20, and 30 % by weight of dry peat and alkali (A) to binder (B) ratio chosen as 0.5, 0.7, and 0.9. The results illustrate that the factors like pH of pore solution, the molarity of NaOH, binder content, A/B ratio, OM, and curing affect the unconfined compressive strength (UCS) of treated peat. The maximum UCS of 962, 873, and 668 kPa was found at an optimum combination of molarity (6M), binder content (20 %), and A/B ratio (0.7) for sapric, fibric, and hemic peat. It was seen that OM has a negative impact, whereas the curing period positively impacts the UCS of treated peat. Furthermore, the cumulative mass loss of fibric peat (13.6 %) is more than hemic (11.4 %) and sapric (10.6 %) peat. The X-ray diffraction patterns and field emission scanning electron microscopy micrographs confirm the cementitious minerals that fill pore spaces or cavities to form a smooth and dense gel responsible for strength gain.

Litter Mass Loss of the Invasive Rhus typhina L. and Native Koelreuteria paniculata Laxm. Trees Alters Soil N-Fixing Bacterial Community Composition under Different N Forms

Soil N-fixing bacterial (NFB) community may facilitate the successful establishment and invasion of exotic non-nitrogen (N) fixing plants. Invasive plants can negatively affect the NFB community by releasing N during litter decomposition, especially where N input from atmospheric N deposition is high. This study aimed to quantitatively compare the effects of the invasive Rhus typhina L. and native Koelreuteria paniculata Laxm. trees on the litter mass loss, soil physicochemical properties, soil enzyme activities, and the NFB. Following N supplementation at 5 g N m−2 yr−1 in four forms (including ammonium, nitrate, urea, and mixed N with an equal mixture of the three individual N forms), a litterbag-experiment was conducted indoors to simulate the litter decomposition of the two trees. After four months of decomposition, the litter cumulative mass losses of R. typhina under the control, ammonium chloride, potassium nitrate, urea, and mixed N were 57.93%, 57.38%, 58.69%, 63.66%, and 57.57%, respectively. The litter cumulative mass losses of K. paniculata under the control, ammonium chloride, potassium nitrate, urea, and mixed N were 54.98%, 57.99%, 48.14%, 49.02%, and 56.83%, respectively. The litter cumulative mass losses of equally mixed litter from both trees under the control, ammonium chloride, potassium nitrate, urea, and mixed N were 42.95%, 42.29%, 50.42%, 46.18%, and 43.71%, respectively. There were antagonistic responses to the co-decomposition of the two trees. The litter mass loss of the two trees was mainly associated with the taxonomic richness of NFB. The form of N was not significantly associated with the litter mass loss in either species, the mixing effect intensity of the litter co-decomposition of the two species, and NFB alpha diversity. Litter mass loss of R. typhina was significantly higher than that of K. paniculata under urea. The litter mass loss of the two trees under the control and N in four forms mainly affected the relative abundance of numerous NFB taxa, rather than NFB alpha diversity.

Freeze-Thaw Damage Characteristics of Concrete Based on Compressive Mechanical Properties and Acoustic Parameters.

Concrete is a versatile material widely used in modern construction. However, concrete is also subject to freeze-thaw damage, which can significantly reduce its mechanical properties and lead to premature failure. Therefore, the objective of this study was to assess the laboratory performance and freeze-thaw damage characteristics of a common mix proportion of concrete based on compressive mechanical tests and acoustic technologies. Freeze-thaw damage characteristics of the concrete were evaluated via compressive mechanical testing, mass loss analysis, and ultrasonic pulse velocity testing. Acoustic emission (AE) technology was utilized to assess the damage development status of the concrete. The outcomes indicated that the relationships between cumulative mass loss, compressive strength, and ultrasonic wave velocity and freeze-thaw cycles during the freezing-thawing process follow a parabola fitting pattern. As the freeze-thaw damage degree increased, the surface presented a trend of "smooth intact surface" to "surface with dense pores" to "cement mortar peeling" to "coarse aggregates exposed on a large area". Therefore, there was a rapid decrease in the mass loss after a certain number of freeze-thaw cycles. According to the three stages divided by the stress-AE parameter curve, the linear growth stage shortens, the damage accumulation stage increases, and the failure stage appears earlier with the increase in freeze-thaw cycles. In conclusion, the application of a comprehensive understanding of freeze-thaw damage characteristics of concrete based on compressive properties and acoustic parameters would enhance the evaluation of the performance degradation and damage status for concrete structures.

Effect of vitamin E–enhanced highly cross-linked polyethylene on wear rate and particle debris in anatomic total shoulder arthroplasty: a biomechanical comparison to ultrahigh-molecular-weight polyethylene

Particle-induced osteolysis resulting from polyethylene wear remains a source of implant failure in anatomic total shoulder designs. Modern polyethylene components are irradiated in an oxygen-free environment to induce cross-linking, but reducing the resulting free radicals with melting or heat annealing can compromise the component's mechanical properties. Vitamin E has been introduced as an adjuvant to thermal treatments. Anatomic shoulder arthroplasty models with a ceramic head component have demonstrated that vitamin E-enhanced polyethylene show improved wear compared with highly cross-linked polyethylene (HXLPE). This study aimed to assess the biomechanical wear properties and particle size characteristics of a novel vitamin E-enhanced highly cross-linked polyethylene (VEXPE) glenoid compared to a conventional ultrahigh-molecular-weight polyethylene (UHMWPE) glenoid against a cobalt chromium molybdenum (CoCrMo) head component. Biomechanical wear testing was performed to compare the VEXPE glenoid to UHMWPE glenoid with regard to pristine polyethylene wear and abrasive endurance against a polished CoCrMo alloy humeral head in an anatomic shoulder wear-simulation model. Cumulative mass loss (milligrams) was recorded, and wear rate calculated (milligrams per megacycle [Mc]). Under pristine wear conditions, particle analysis was performed, and functional biologic activity (FBA) was calculated to estimate particle debris osteolytic potential. In addition, 95% confidence intervals for all testing conditions were calculated. The average pristine wear rate was statistically significantly lower for the VEXPE glenoid compared with the HXLPE glenoid (0.81 ± 0.64 mg/Mc vs. 7.00 ± 0.45 mg/Mc) (P<.05). Under abrasive wear conditions, the VEXPE glenoid had a statistically significant lower average wear rate compared with the UHMWPE glenoid comparator device (18.93 ± 5.80 mg/Mc vs. 40.47 ± 2.63 mg/Mc) (P<.05). The VEXPE glenoid demonstrated a statistically significant improvement in FBA compared with the HXLPE glenoid (0.21 ± 0.21 vs. 1.54 ± 0.49 (P<.05). A newanatomic glenoid component with VEXPE demonstrated significantly improved pristine and abrasive wear properties with lower osteolytic particle debris potential compared with a conventional UHMWPE glenoid component. Vitamin E-enhanced polyethylene shows early promise in shoulder arthroplasty components. Long-term clinical and radiographic investigation needs to be performed to verify if these biomechanical wear properties translate to diminished long-term wear, osteolysis, and loosening.

Erosion wear analysis of heat exchange surfaces in a falling particle-based concentrating solar power system

Next generation concentrating solar power (CSP) plants that use solid particles as the heat transfer and storage medium provide opportunities for higher temperature operation, higher efficiency, and lower levelized cost. However, falling particles over component material surfaces can cause significant erosion, severely limiting the performance and operational service life of the components. An understanding of the particle erosion wear of heat transfer surfaces is imperative for designing components and operating conditions to minimize wear. Considering a shell-and-tube heat exchanger configuration, this study presents a computational analysis coupling falling particle flow around heat exchanger tubes and particle-scale erosion of the tube surfaces governed by the Finnie model. Several tube arrangements, particle flow and geometric parameters, and tube material parameters are systematically investigated for their effects on the erosion rate spatially and with time. Parameters that influence the erosion depth, the cumulative mass loss rate and the maximum erosion rate are elucidated. The results of the study may be used to help identify locations that experience the most erosion and devise ways for targeted erosion mitigation.

Designing Cu chemical distribution in Ti(AlCu)N coatings for enhanced erosion-corrosion and antibacterial performance

In order to enhance the erosion-corrosion resistance and antibacterial property simultaneously, we prepared PVD TiAlCuN coatings with periodically modulated TiAlCuN/TiAlN sublayers near the topmost surface. Firstly, Ti(AlCu)N phase and Cu nano-precipitates formed in TiAlCuN sublayers can improve coating mechanical performance. Secondly, apart from reducing galvanic corrosion potential, the Cu ions could preferentially diffuse upward to the topmost surface, along the grain boundaries in the columnar TiAlN sublayers, leading to Cu ions at the topmost surface and good antibacterial property. The interfaces between TiAlN and TiAlCuN sublayers can act as multiple barriers to crack propagation and prevent severe coating spallation. The optimized coating exhibits i) the lowest cumulative mass loss and erosion-corrosion rate after 24 h erosion-corrosion testing, which associates with the improved mechanical property and good corrosion resistance, and ii) excellent antibacterial property against Escherichia coli (E. coli) with an antibacterial rate of 99.68 % and a live/dead bacteria proportion of 7.40 %/92.60 %, due to the advanced homeostasis work of the primordial surface Cu ions. The design of modulating the surface Cu chemical distribution achieved by subsurface column-layer architecture provides a new design concept for incorporation of Cu in coatings for the applications of metal parts in critical marine environment.

Extended Nutritional Monitoring in Patients Undergoing Intensive Chemotherapy for Acute Myeloid Leukemia

Background Fit patients (pts) with acute myeloid leukemia (AML) are conventionally administered repeated cycles of intensive chemotherapy, often followed by allogeneic hematopoietic stem cell transplant. AML pts need to be long hospitalized in a protected setting, they are often prescribed a neutropenic diet and chemotherapy-induced gastro-intestinal toxicity is common. As a result, malnutrition is frequently observed, it sensibly reduces the quality of life and has the potential to undermine eligibility for intensive treatment, increase treatment-related toxicity, and ultimately reduce survival. Aims Aim of this study was to systematically assess the nutritional status of fit pts undergoing treatment for AML and to explore early predictors and associations with known nutritional risk scores and relevant clinical outcomes. Methods Nutritional Risk Screening 2002 (NRS) score was calculated for each patient at time of diagnosis (a score of 3 or more is considered high). Then, nutritional monitoring included standard anthropometric measurements (body weight, BW; body mass index, BMI) and a bioelectrical impedance analysis (BIA) performed by a registered dietitian to assess fat-free mass, body cell mass (BCM, the metabolically active component of body mass), fat mass and the phase angle. Variations in nutritional parameters between admission and day 7 (end of CHT, called “dif7”) or between admission and day 14 (called “dif14”) were calculated and tested for correlation with variations of the same parameter at discharge from the same cycle (called “dif30”) or at discharge after the first consolidation (called “dif60”). Results Up to now, 26 pts with newly diagnosed AML (median age 55y, range 21-74) were prospectively monitored during a total of 61 cycles of intensive chemotherapy (35 induction cycles, 26 consolidation cycles). Median NRS score at enrolment was 3 (range 2-6). Median follow up for surviving pts is 300 days. We observed a significant reduction in fat-free mass and body cell mass during induction cycles. Similar trends, although not significant, were observed for consolidation cycles as well. These trends were observed irrespectively of baseline NRS, disease response, or whether admission was complicated by a fever lasting more or less than 7 days. A high NRS score was only associated with a greater fat mass loss between diagnosis and discharge after first consolidation (FM dif60), but the score failed to predict any meaningful nutritional parameter variation. For fat-free mass, body cell mass and the phase angle (but not for BW or BMI), dif7 correlated with dif30 for induction and consolidation cycles. For body cell mass and the phase angle, both dif7 and dif14 also correlated with dif60. Only variations in body cell mass at day 7 (BCM dif7) correlated with cumulative weight loss at discharge after the first consolidation cycle (BW dif60). Reduction in BW, BMI and fat mass at day 7, and of phase angle at day 14, were associated with extended length of stay for consolidation chemotherapy cycles only. Conclusions In this study, pts intensively treated for AML suffered a significant reduction in the metabolically active component of body mass during admission for induction chemotherapy and, cumulatively, during the first two treatment cycles. Bioelectrical impedance analysis performed as early as seven days from admission could already reveal the first signals of nutritional deterioration: body cell mass loss between day 0 and day 7 correlated with both cumulative body cell mass loss and cumulative body weight loss after two cycles of chemotherapy. Notably, a commonly used nutritional risk screening tool failed to predict the risk of malnutrition in our cohort of patients. “NUTRIAMO” is a prospective, observational trial currently starting at our institution, where pts intensively treated for AML are monitored via known nutritional assessment tools, new biochemical markers (e.g., prealbumin and retinol-binding protein) and microbiome analysis and variations. Our aim is to find more sensitive nutritional triggers to activate earlier and more effective support measures (e.g., oral nutritional supplements, diet variations, psychological support) and ultimately improve AML patients' quality of life and survival beyond the cure of their disease.

Effects of extreme melt events on ice flow and sea level rise of the Greenland Ice Sheet

Abstract. Over the past decade, Greenland has experienced several extreme melt events, the most pronounced ones in the years 2010, 2012 and 2019. With progressing climate change, such extreme melt events can be expected to occur more frequently and potentially become more severe and persistent. So far, however, projections of ice loss and sea level change from Greenland typically rely on scenarios which only take gradual changes in the climate into account. Using the Parallel Ice Sheet Model (PISM), we investigate the effect of extreme melt events on the overall mass balance of the Greenland Ice Sheet and the changes in ice flow, invoked by the altered surface topography. As a first constraint, this study estimates the overall effect of extreme melt events on the cumulative mass loss of the Greenland Ice Sheet. We find that the sea level contribution from Greenland might increase by 2 to 45 cm (0.2 % to 14 %) by the year 2300 if extreme events occur more frequently in the future under a Representative Concentration Pathway 8.5 (RCP8.5) scenario, and the ice sheet area might be reduced by an additional 6000 to 26 000 km2 by 2300 in comparison to future warming scenarios without extremes. In conclusion, projecting the future sea level contribution from the Greenland Ice Sheet requires consideration of the changes in both the frequency and intensity of extreme events. It is crucial to individually address these extremes at a monthly resolution as temperature forcing with the same excess temperature but evenly distributed over longer timescales (e.g., seasonal) leads to less sea level rise than for the simulations of the resolved extremes. Extremes lead to additional mass loss and thinning. This, in turn, reduces the driving stress and surface velocities, ultimately dampening the ice loss attributed to ice flow and discharge. Overall, we find that the surface elevation feedback largely amplifies melting for scenarios with and without extremes, with additional mass loss attributed to this feedback having the greatest impact on projected sea level.

Reconstructing runoff components and glacier mass balance with climate change: Niyang river basin, southeastern Tibetan plateau

The southeastern part of the Tibetan Plateau (TP), one of the regions with the largest glacier distribution on the plateau, has been experiencing a significant loss in glacier mass balance (GMB) in recent decades due to climate warming. In this study, we used the Spatial Processes in Hydrology (SPHY) model and satellite data from LANDSAT to reconstruct the runoff components and glacier mass balance in the Niyang River basin (NRB). The measured river discharge data in the basin during 2000–2008 were used for model calibration and validation. Then, the validated model was applied to reconstruct the runoff components and GMB in the Niyang River basin for the period 1969–2013. Results showed that rainfall runoff (67%) was the dominant contributor to total runoff, followed by snowmelt runoff (14%), glacier melt runoff (10%), and baseflow (9%). The NRB experienced a severe loss in GMB, with a mean value of −1.26 m w. e./a (corresponding to a cumulative glacier mass loss of −56.72 m w. e.) during 1969–2013. During periods Ⅰ (1969–1983), Ⅱ (1984–1998), and Ⅲ (1999–2013) glacier mass loss was simulated at rates of −1.27 m w. e./a, −1.18 m w. e./a, and −1.33 m w. e./a, respectively. The annual loss of glacier mass in the northern region of the NRB (−1.43 m w. e./a) was significantly greater than that of the southern region (−0.53 m w. e./a) from 1969 to 2013, largely due to temperature variations, especially in summer months. These findings enhance our understanding of how different hydrological processes respond to climate change and provide a potential method to study runoff components and GMB in other glacierized catchments worldwide.

Experimental Research Regarding the Effect of Mineral Aggregates on the Wear of Mixing Blades of Concrete Mixers.

Industrial mixers are equipment used to mechanically combine different types of materials in order to obtain homogeneous mixtures. In concrete industry production, mixers play a crucial role by facilitating the efficient and consistent blending of various constituents to create high-quality concrete. Because the mixers in the concrete industry work in conditions characterized by abrasive and erosive loadings, the authors of this paper tried to establish a dependence between the quality of the material from which the mixing elements are made and their wear resistance. Three types of cast irons alloyed with chromium, specific to the construction of mixing blades, were used in this research. The working environment was a mixture of crushed mineral aggregates corresponding to the granulometric class 4-8 mm. The tests were carried out on an experimental stand designed and built by the authors of this paper. The stand reproduces on a scale of 1:2 a drum made up of a double-axis horizontal mixer. The stand had the possibility to change the value of the attack angle of the mixing blades, corresponding to the following values: 30, 45, and 60 degrees. The results of the tests established the dependence between the type of material and the wear rate of the blades as well as the influence exerted by the angle of attack on the wear of the mixing blades. It was shown that when the inclination angle of the blade relative to the shaft axis increases, the cumulative mass loss decreases, with values between 43% and 55.83%, as a function of the quality of blade material.

Future state of Norwegian glaciers: Estimating glacier mass balance and equilibrium line responses to projected 21st century climate change

Glaciers and ice caps in Norway are presently undergoing mass loss, areal reduction, and frontal retreat, mainly a result of increased summer ablation due to rising summer temperatures over Scandinavia, especially after 2000 CE. In this paper, the glacier mass-balance response of 10 Norwegian glaciers with continuous mass balance observations (&gt;10 years) to climate projections from 1971–2000 to 2071–2100 have been estimated. Projected changes in mean summer temperature and mean winter precipitation from 1971–2000 to 2071–2100, applying the RCP8.5 emission scenario for five different regions in Norway; ‘Sogn og Fjordane’ and ‘Hordaland’, now Vestland County in western Norway, ‘Oppland’, now part of Innlandet County in eastern Norway, and Nordland County and Finnmark County, both in Northern Norway), range between +3.5°C and +5.0°C, and between +5% and +25%, respectively. These climate projections have been converted (by linear regression with overlapping observational mass-balance data) into specific surface glacier mass balance [winter balance ( Bw), summer balance ( Bs), and annual balance ( Ba) for 10 glaciers in Norway with mass-balance series [Ålfotbreen, Nigardsbreen (part of Jostedalsbreen), Austdalsbreen (part of Jostedalsbreen), Rembesdalskåka (part of Hardangerjøkulen), Blomstølskardsbreen (part of Søre Folgefonna), Storbrean, Hellstugubrean, Gråsubrean, Engabreen (part of Vestre Svartisen, Langfjordjøkelen (data: http://glacier.nve.no/glacier/viewer/ci/no/ ) yielding a total, cumulative surface glacier mass loss from 2000 to 2100 CE in the range of -85.2 ± 4 to -197.3 ± 10 m water equivalents. The estimated changes in equilibrium-line altitudes (ELAs), in the range of 230 ± 10 to 630 ± 30 m, indicate that the mean ELA may reach the upper part of 7 of the 10 glaciers included in this study [Ålfotbreen, Austdalsbreen, Rembesdalskåka, Blomstølskardsbreen, Gråsubrean, Engabreen and Langfjordjøkelen] by the end of the 21st century. The projected glacier mass loss and ELA rise, and thus changes in glacier length, area and volume, will most likely have profound consequences for future glacier hydrology (runoff), hydropower production, wildlife, ecosystems, glacier hazards, and tourism.

The coupling effect of cavitation-erosion and corrosion for HVOF sprayed Cu-based medium-entropy alloy coating in 3.5 wt.% NaCl solution

Ship propellers suffered from serious coupling damage of cavitation-erosion (CE) and corrosion when operated with high-speed in the marine environment. To improve the CE-corrosion resistance of the Ni–Al bronze (NAB) propeller alloy, a novel Cu-based medium-entropy alloy coating (Cu55Al20Ni12Ti8Si5, at.%) was prepared by high-velocity oxygen-fuel spraying technology in this study. The characteristics and CE behavior of coating and NAB were comparatively investigated, then the CE damage mechanism was discussed by analyzing CE damage morphologies. The influence of CE on corrosion behavior and the coupling effect between CE and corrosion were further elucidated by electrochemical corrosion experiments. The results indicated that the as-sprayed coating mainly comprised of BCC solid solution phase and NiTi-rich precipitates, which possessed higher hardness (6.73 ± 1.23 GPa) and superior resilience (27.0%) than the NAB. The cumulative mass loss rate for the coating after 18 h CE in distilled water and 3.5 wt.% NaCl solution was only 38.7% and 80.6% that for the NAB, revealing the better anti-CE performance of the coating. The preferential CE of the BCC matrix around the NiTi-rich precipitates, fatigue fracture and lamellar spalling were summarized as the main CE damage mechanism for the coating in 3.5 wt.% NaCl solution. CE had a significant influence on corrosion behavior of coating and NAB, which resulted in corrosion performance degradation of both two materials. The CE-corrosion coupling effect led to the remarkable mass loss, and mechanical effect rather than corrosion effect was ascribed to be the dominated factor for the damage of coating and NAB.

Cavitation erosion-corrosion behaviour of Fe-19Cr-15Mn-0.66 N high nitrogen austenitic stainless steel in sodium chloride solution

In this work, the cavitation erosion (CE)-corrosion behaviors of high nitrogen austenitic stainless steel (HNSS) Fe-19Cr-15Mn-0.66 N were investigated under both static and CE conditions in 0.5 mol l−1 NaCl solution. For the sample after 8 h CE, the cumulative mass loss increased by 15% in 0.5 mol l−1 NaCl solution compared to distilled water, indicating that the corrosive media promoted mass loss. The corrosion behavior of the samples under static and CE conditions was evaluated using electrochemical techniques. The results showed that compared with the samples under static conditions, the samples under CE had a higher corrosion rate, and the corrosion resistance of the samples gradually decreased with the prolongation of C E time.The open circuit potential and potentiodynamic polarization tests showed a higher corrosion rate under CE conditions. The electrochemical impedance spectroscopy results revealed a decrease in corrosion resistance with increasing CE time. The XPS results showed that CE has a significant effect on the composition of the passive film, promoting a notable increase in Cr2O3 and Fe2O3.

Effect of Heat Treatment on the Cavitation Erosion Behavior of Nanocrystalline Surface Layer of 304 Stainless Steel

In this study, a nanocrystalline layer composed primarily of martensite phase was prepared on the surface of 304 stainless steel. Furthermore, the martensite phase content in the nanocrystalline layer was adjusted by heat treatment at 500 °C and 550 °C, respectively, and the cavitation erosion resistance of the nanocrystalline layer before and after heat treatment was investigated. The results showed that the nanocrystalline layer before and after heat treatment exhibited excellent erosion resistance, with cumulative mass loss of approximately 1/7, 1/5, and 1/3 that of the traditional 304 stainless steel, respectively. The nanocrystalline layer could significantly inhibit the growth of cavitation pits due to the high density of grain boundaries. However, due to the decrease in hardness of the nanocrystalline layer after heat treatment, the propagation speed of cavitation cracks was accelerated, and the cavitation erosion performance of the nanocrystalline layer showed a downward trend.