Dry Environment Research Articles

An investigation on tribology performance of Abutilon Indicum fibre reinforced polymer composites

This research work investigates the tribological characteristics of Abutilon Indicum Fiber (AIF) reinforced composites with epoxy as the binding agent. The Abutilon Indicum fiber reinforced composites were manufactured by compression molding technique. These composites were fabricated by varying the fiber volume fraction ranging from 5%, 10%, 15% and 20% respectively and considering the fiber length as a fixed factor due to its short length. This research paper illustrates the effects of different fiber volume fractions (5,10,15 and 20%) on the tribological properties such as Specific wear rate (SWR) and Coefficient of friction (µ) of Abutilon Indicum fiber reinforced composites. Sliding wear tests were carried out under dry environment conditions with pin-on-disc wear testing machine. The experiments were performed for each composite with different combinations of testing parameters, sliding loads (10, 20 and 30 N); sliding distances (1,2 and 3 km); sliding speeds (1,2 and 3 m/s). Shore D hardness of 78.22 is determined to be higher for 15% volume fraction of AIF composites. Results conclude that the addition of AIFs in these composites enhanced the tribological performance with good wear resistance in relation with the pure epoxy-based composites with 15% volume fraction of AIFs displaying best results with higher resistance to wear at various operating conditions. Composites produced with 20% volume fraction displays the effects of fiber agglomeration which in turn has an inverse effect on hardness; limits the wear resistance with higher friction and wear rate and such results agree well with the wear debris, pits and contact patches in micrographs. Optimal fiber volume fraction of 15% was suggested in fabrication of composites for usage of AIFs as friction material.

Tribological characteristics of graphene nanoplatelets-filled PTFE under dry sliding and sea water environmental conditions

This study focuses on enhancing the tribological performance of polytetrafluoroethylene (PTFE) composites by incorporating graphene nanoplatelets (GNPs) through compression moulding technique. The main aim of the research was to investigate how varying weight percentages of GNP (1 wt %, 3 wt % and 5 wt %) influence the friction and wear properties of PTFE composites under both dry sliding and saline water environment. A significant reduction in the coefficient of friction (COF) and wear rate was observed with the addition of GNP, particularly in seawater. Specifically, the reduction of COF in sea water reached up to 58.765% with 3% of GNP compared to dry sliding. For wear reduction, a reduction of up to 90.247% was observed with 5% GNP in sea water condition. These findings reveal the potential of GNP-filled PTFE composites in applications requiring enhanced tribological properties in both dry and aqueous environments. The originality of this work lies in the comprehensive analysis of the environmental influence on GNP-filled PTFE composites, providing understandings of their applicability in marine environments.

Determination of rates of occurrence for hydroplaning events with naturalistic driving data

Introduction: The degree to which hydroplaning occurs in real-world conditions is not entirely known. Naturalistic driving data can be helpful in addressing some of the limitations of existing data sources related to the incidence of hydroplaning. Method: Data from the Second Strategic Highway Research Program Naturalistic Driving Study were leveraged to estimate the incidence of hydroplaning. Two hydroplaning detection algorithms were used for candidate hydroplaning event generation. Hard braking events were also identified and analyzed as normative comparisons to the hydroplaning events. Results: A total of 1,141 hydroplaning events were found in the naturalistic driving data and utilized for analysis, including 650 hydroplaning events that were unnoticeable by the driver based on lack of observable reactions, 13 events that were deemed to be of “critical” severity, and only 3 events that resulted in crash events during more than 30 million miles of driving. Hard braking events occurred nearly four times more often, and at comparatively lower speeds, than hydroplaning events. Observable driver reactions also differed between event types. For example, more drivers changed their posture after a hydroplaning event than after a hard braking event and drivers maintained both hands on the wheel at higher rates after experiencing a hydroplaning event than after a hard braking event. Suspension of secondary tasks during hard braking and hydroplaning events was also observed. Conclusions: Overall, these findings suggest that drivers perceive hydroplaning events as more harmful than hard braking events, despite the large discrepancy and incompatibility in how often these driving situations lead to vehicular crashes. Practical application: The findings of this research will provide vehicle and tire designers with empirical data that quantifies the important tradeoffs they must make in balancing vehicle and tire performance in wet and dry environments, and in tradeoffs related to tire wear performance and grip.

Time-varying moisture characteristics and C-S-H gel properties of concrete in dry and hot environments

The construction of deeply buried tunnels has intensified concerns regarding shrinkage cracking and the long-term performance deterioration of lining concrete in dry-hot environments. These issues are related to the dynamic interconversion of internal moisture states, the changing moisture behavior over time, and the evolution of calcium silicate hydrate (C-S-H) properties. However, the mechanisms underlying these phenomena are not fully understood. This study investigates the dynamics of moisture content across different states, the source and composition of evaporated water, as well as the mechanism of change in the microscopic properties of C-S-H in concrete subjected to dry-hot conditions (40℃ and 60℃) and standard curing environments through tests on water loss rates, chemically bound water, and low-field nuclear magnetic resonance. The findings reveal that at 40℃ and 60℃, hydration products were generated rapidly before mold removal, leading to significant increases in chemically bound water, interlayer water, and gel water, while capillary water was notably consumed. After mold removal, the rate of chemically bound water increase slowed, while interlayer water, gel water, and capillary water evaporated significantly, with gel water comprising 87.27 % and 83.51 % of the evaporated water at 40℃ and 60℃, respectively. From day 1 to day 28, interlayer water, gel water, and capillary water contents decreased significantly, with reductions of up to 85.98 % at 60℃. In dry-hot environments, moisture primarily exists as chemically bound water and gel water, contrasting with standard curing conditions where capillary water is also present. The study concludes that drying of C-S-H gels leads to both positive effects, such as interlayer space compression and increased indentation modulus, and negative effects, including increased microporosity and reduced matric densification, ultimately contributing to the deterioration of long-term mechanical properties.

Structure and function of skin barrier lipids: Effects of hydration and natural moisturizers in vitro

Lipid membranes play a crucial role in regulating the body’s water balance by adjusting their properties in response to hydration. The intercellular lipid matrix of the stratum corneum (SC), the outermost skin layer, serves as the body’s primary defense against environmental factors. Osmolytes, including urocanic acid (UCA) and glycerol, are key components of the natural moisturizing factor that help the SC resist osmotic stress from dry environments. This study examines the effects of UCA and glycerol (each at 5 mol %) on isolated human SC lipids. For this, different techniques were employed, offering complementary information of the system’s multiscale characteristics, including humidity-scanning quartz crystal microbalance with dissipation monitoring, infrared spectroscopy, x-ray diffraction, electrical impedance spectroscopy, and studies of water loss and permeability. Our results show that UCA increases water sorption and makes lipid films more liquid-like at high relative humidity, without significantly altering the lipid lamellar structure, chain order, or orthorhombic chain packing. Lipid films containing UCA exhibited higher water loss and significantly higher model drug permeability compared to lipid films without UCA. Further, incorporation of UCA resulted in kinetically faster changes in electrical properties upon contact with aqueous solution compared with control lipids. These observations suggest that UCA reduces lipid cohesion in regions other than the acyl chain-rich leaflets, which may impact SC desquamation. In contrast, glycerol did not influence the hydration or permeability of the SC lipid matrix. However, it increased the proportion of orthorhombic domains at high humidities and slowed the kinetics of the hydration process, as evidenced by slower changes in the dielectric properties of the lipid film. These findings suggest that glycerol enhances lipid cohesion rather than increasing water uptake, which is typically the expected function of humectants. Consequently, UCA and glycerol appear to have distinct roles in maintaining epidermal homeostasis.

Durability Assessment of Hybrid Double-Skin Tubular Columns under Wet–Dry Cyclic Environments

Durability Assessment of Hybrid Double-Skin Tubular Columns under Wet–Dry Cyclic Environments

A Foam of Blocks: Lawrence Halprin’s Architectural Language:A Crossing through the Venetian Wilderness: Architectures 1979-1999

This paper is part of a bigger study on Lawrence Halprin, conducted through the analysis of his personal archives present at the University of Pennsylvania, Philadelphia, and the Seattle’s City archives, together with trips and dedicated surveys for some of his projects. Many of Halprin’s urban projects are culturally linked to the 60s and 70s: the assassination of Martin Luther king Jr in Memphis and of Robert Kennedy in Los Angeles, the student protests against the Vietnam War, and the subsequent occupying of university campuses, and the violent clashes between protesters and the police. Yet as public space became the stage for confrontation in many American cities, Halprin’s open space projects seemed to encourage a different type of use: joyful playfulness, performance, dace. Many of his designs in fact, were developed with the idea of performance in mind, not surprising, as Halprin’s wife, Anna Halprin, was an important contemporary dancer and choreographer with whom he collaborated often, as well as one of his collaborators, Angela Danadjieva, a former designer of constructivist-inspired sets for Bulgarian state films. Larger urban renewal interventions were also fueled by the Federal Housing Act of 1949 that encouraged “slum removal”, inner cities-neighborhoods deemed beyond repair, and the “Federal-Aid Highway Act” of 1968, that encouraged the construction of superhighways to increase connectivity between cities and states. What appeared simply radical, is the fundamentally traditional idea of designing public spaces within the city with the deliberate intention for them to be beautiful and pleasurably utilized by the surrounding communities. These ideas had simply been replaced by design principles developed for the car, like multi lane roads, parking lots, shopping centers, drive thrus, etc.... The significance of these spaces can be seen for example in the Portland sequence – “Lovejoy Fountain, Pettygrove Park, and Forecourt (later renamed Ira Keller) Fountain, along with the lesser-known Source Fountain – represented a new kind of urban plaza, a grandly sculptural, metaphorical experience of nature that welcomed an activity largely absent from the midcentury American downtown: play”. Skyline park in Denver, project that linked together three downtown blocks also encouraged play though the creation of metaphorical high-mountain cascades, canyons and open fields, designed through a series of fractured geometries of blocks and water basins for fountains. The presence of water features is a constant in Halprin’s designs, inspired by the wet and dry environments of the High Sierra. In fact, Halprin believed that only with flowing water can true beauty be achieved. This is very visible in all of his fountains but perhaps particularly in Seattle’s Freeway Park, where the water cascades, with their loud roaring manage to drown out the sounds of the adjacent freeway. His fountains are actual pieces of wilderness, geometrically mutated and transplanted into the city that with their glittering and static effects, without any type of barrier, effectively invite active participation, and encourage human activities like splashing, climbing, crawling, bathing, contemplating... In a cultural context that seemed to promote separation and isolation between different parts of established cities, Lawrence Halprin, with small or large commissions in Portland, San Francisco, Minneapolis, Denver, Seattle attempted (and in many ways succeeded) to create connections on the small, urban, human scale. By the 1990s, Halprin’s blend of nature, theater and urbanism would be established in a growing collection of plazas, and parks that, in each case, set the stage for major new public spaces.

Mechanism of Boron Carbide Oxidation in a Dry Environment

ABSTRACT We analyze in detail the published experimental data on the high-temperature oxidation of compact boron carbide in dry oxygen in the range of 600–1200°C. The results of the analysis show that the oxidation of boron carbide occurs with the accumulation of excess (compared to stoichiometry) boron. Using experimental data, the time dependences of the thickness of the boron oxide melt layer formed on the sample surface during its oxidation and the mass of boron oxide evaporated from the sample surface are determined. For different temperatures, the evaporation rates of boron oxide are determined. Based on the analysis, a model of the high-temperature oxidation of compact boron carbide in dry environment was developed. Using the developed model, calculations of the process of boron carbide oxidation at different temperatures were carried out. Based on the results of calculations, the time dependences of the mass of the sample, the mass of the resulting carbon dioxide, and the thickness of the boron oxide melt layer were determined. The calculation results are compared with the experimental data and with the theoretical temperature dependence of the boron oxide melt evaporation rate, calculated using the Hertz – Knudsen equation. Based on the simulation results, it is concluded that the rates of chemical reactions are finite, and the process of B4C oxidation cannot be reduced only to oxygen diffusion through the boron oxide layer.

WebMRT: An online tool to predict summertime mean radiant temperature using machine learning

Mean Radiant Temperature (Tmrt) is the most critical atmospheric variable influencing outdoor human thermal exposure and comfort in hot, dry environments. However, accurately quantifying Tmrt requires time-consuming field measurements with expensive equipment or complex, resource-intensive computations. We introduce WebMRT, an online tool to predict Tmrt using a data-driven approach. It features an intuitive interface using air temperature, shading status, and built environment features as predictors of Tmrt for a user-selected summer day, time, and location. Utilizing a tree-based ensemble model, WebMRT is trained on state-of-the-art human-biometeorological data collected by MaRTy using LightGBM after evaluating its performance against several candidate machine learning regressors. Feature engineering was applied to the day and time input, and two additional temporal features were derived: ‘Solar Altitude’ and ‘Minutes-from-Sunrise’. These inputs are integrated into the user interface, emphasizing simplicity and easy access for users at the frontend. After training the regressor on MaRTy datasets and employing k-fold cross-validation with ten folds, the model demonstrated strong predictive power (R2=0.92) with acceptable error (RMSE=3.43, MAPE=5.33) and bias (MBE=0.20). WebMRT also features optional fisheye photo uploads, processed using transfer learning techniques for image segmentation, further enhancing the tool's predictive accuracy, user experience, and applications towards climate action decision-making processes.

Molecular dynamics study on bonding behaviors of γ–FeOOH/CSH interface under aggressive conditions

The steel fiber reinforced concrete structure exposed to the marine environment is vulnerable to the intrusion of water and aggressive ions, especially the interface between concrete and steel fibers, which affects their bonding behaviors and causes durability defects. In this paper, molecular dynamics simulation is used to elucidate the effects of water and ions on the bonding behaviors and mechanical responses of concrete and steel fiber interface under different environmental exposures. On the basis of the formation of CaCSH–Owater bonds and hydrogen bonds between water and CSH, aggressive ions further attract H2O molecules to CSH surface and occupy the coordination site between CSH and γ–FeOOH, leading to the reduction of their interaction energy and a decline in the bonding behaviors of the γ–FeOOH/CSH interface. The order of interfacial bonding deterioration degree affected by environment is NaCl + Na2SO4 > Na2SO4 > NaCl > Water > Dry. In the NaCl + Na2SO4 environment, the interaction energy of γ–FeOOH/CSH interface is reduced by 31.2 %, and the shear strength of γ–FeOOH has a reduction of 58.8 % compared with the dry environment.

Hohenbergia alba and Hohenbergia sparsiflora, two striking new bromeliads from the Brazilian Atlantic Forest

We present two new species, Hohenbergia alba and H. sparsiflora, endemic to the Brazilian Atlantic Forest in the southern region of the state of Bahia. These species were identified as understory epiphytes in forest fragments near highways. These newly described species are morphologically similar to the “giant Hohenbergia species group”, characterized by their significantly larger size compared to species found in the highlands and dryer environments. Notable unique features include the compact rosette and a 3-4-branched inflorescence with white-colored petals for H. alba and sparsely-flowered spikes for H. sparsiflora, a feature not yet reported for the genus. Additionally, we provide illustrations, and a comparative table of morphological data of these species and related taxa, as well as information on the conservation status and phenology.

The genomes of Australian wild limes

Australian wild limes occur in highly diverse range of environments and are a unique genetic resource within the genus Citrus. Here we compare the haplotype-resolved genome assemblies of six Australian native limes, including four new assemblies generated using PacBio HiFi and Hi-C sequencing data. The size of the genomes was between 315 and 391 Mb with contig N50s from 29.5 to 35 Mb. Gene completeness of the assemblies was estimated to be from 98.4 to 99.3% and the annotations from 97.7 to 98.9% based upon BUSCO, confirming the high contiguity and completeness of the assembled genomes. High collinearity was observed among the genomes and the two haplotype assemblies for each species. Gene duplication and evolutionary analysis demonstrated that the Australian citrus have undergone only one ancient whole-genome triplication event during evolution. The highest number of species-specific and expanded gene families were found in C. glauca and they were primarily enriched in purine, thiamine metabolism, amino acids and aromatic amino acids metabolism which might help C. glauca to mitigate drought, salinity, and pathogen attacks in the drier environments in which this species is found. Unique genes related to terpene biosynthesis, glutathione metabolism, and toll-like receptors in C. australasica, and starch and sucrose metabolism genes in both C. australis and C. australasica might be important candidate genes for HLB tolerance in these species. Expanded gene families were not lineage specific, however, a greater number of genes related to plant-pathogen interactions, predominantly disease resistant protein, was found in C. australasica and C. australis.

Evaluation of entropy-coupled multi-criteria decision-making methods for enhancing machinability

Optimizing machining parameters is crucial, enhancing machinability while maintaining high product quality standards. This study bridges a critical research gap by evaluating and comparing five Taguchi-based Multi-Criteria Decision Making (MCDM) techniques—Combined Compromised Solution (CoCoSo), Grey Relational Analysis (GRA), Multi-Objective Optimization Ratio Analysis (MOORA), Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), and Complex Proportional Assessment (COPRAS)—coupled with the Entropy method to optimize machining parameters for enhancing machinability in turning medium carbon steel. The focus is on feed rate and cutting speed under dry and Minimum Quantity Lubrication (MQL) environments considering six critical machining responses: material removal rate, surface roughness, main cutting force, cutting temperature, cutting ratio, and tool life.The results reveal that MQL consistently improves machining performance, with COPRAS, TOPSIS, MOORA, and GRA converging on an optimal setting favoring an MQL environment, a 0.14 mm/rev feed rate, and a cutting speed of 137 m/min, whereas CoCoSo suggests a different optimal parameter setting. CoCoSo and GRA demonstrate the highest reliability, evidenced by minimal discrepancies between predicted and experimental results, with absolute percentage errors of 0.647 % and 0.659 %, respectively. The COPRAS method also shows strong predictive accuracy with a 5.573 % error, outperforming MOORA and TOPSIS. Spearman's rank correlation analysis reveals a high agreement between COPRAS, MOORA, and TOPSIS, with COPRAS emerging as a potential replacement for the latter in similar decision-making scenarios. SEM and EDX analyses confirm that MQL conditions reduce tool wear, enhance surface quality, and extend tool life compared to dry machining. This research provides insights into effective parameter optimization strategies for improving machinability and underscores the benefits of adopting MQL for sustainable manufacturing processes.

Feasibility of ultrasonic non-destructive testing of ancient funerary urns: Experimental and analytical parametric model

Non-invasive modalities are being developed as the computer tools and industrial non-destructive testing capabilities become more widespread. Using the same investigation methods as those applied to modern objects, we seek to study ancient funerary urns containing human bones. The exploration of ancient urns is key to increasing our understanding of the practices of burial and cremation in archaeo-anthropology. But those urns present at archaeological sites are exposed to diversified environments (wet, temperate or dry environment), and can be subjected to chemical or mechanical destructive actions over time. As ancient funeral urns containers are sometimes made of lead, stone or ceramic, the use of X-ray scanners is difficult or even impossible for in situ control. In this work, we propose an engineering technique based on ultrasonic non-destructive testing and wave propagation in urns. An analytical parametric model is developed using mathematical signal processing tools and validated by means of laboratory experiments under controlled conditions of propagation through reproductions of ancient urns for two ultrasonic frequencies (500 kHz and 1 MHz). The aim is to characterise an ancient urn by creating an analytical model, and to use a parametric identification algorithm to determine the presence or absence of bone fragments. The parametric identification algorithm based on the Levenberg–Marquardt method makes it possible to determine the geometrical (thickness) and physical (wave velocity and attenuation, mass density) parameters when the urn is filled with water, with water and bones, and with water, bones and sand. We show that the model makes it readily (processing time ≈15 sec) possible to find the different times of flight between the transducer and the different walls of the urn and the parameters with an accuracy less than 10%.

Pre-, Per- and post-cooling strategies used by competitive tennis players in hot dry and hot humid conditions.

This research investigated the pre-, per- and post cooling strategies used by competitive tennis players from various levels of play who occasionally train and compete in hot (>28°C) and humid (>60% rH), and dry (<60% rH) environments. 129 male tennis players (Mage = 24.9) competing at regional (N = 54), national (N = 30) and international (N = 45) levels, completed an online questionnaire regarding their use (i.e., timing, type, justification and effectiveness) of pre- (i.e., before practice), per- (i.e., during exercise) and post-cooling strategies when playing tennis in hot dry (HD) and hot humid (HH) conditions. Individual follow-up interviews were also carried on 3 participants to gain an in-depth understanding of the player's experience. Competitive tennis players used both internal and external cooling strategies to combat the negative effects of HD and HH conditions, but considered the HH to be more stressful than HD and experienced more heat-related illness in HH environments. International players used cold packs and cold towel more frequently than the regional and national players in hot environments, and used cold water immersion and cold vest more frequently than the latter in HH. Differences in strategy use were mostly observed during per-cooling where regional and national players more frequently used cold drinks than international players who more frequently used cold packs in HD and cold towel in HH conditions. Moreover the latter more frequently used cold towel, cold packs and cold water immersion as post-cooling strategies than regional players. When playing tennis in the heat, it is strongly recommended to employ cooling strategies to maintain health, limit declines in performance, and promote recovery. We also recommend improving education regarding the appropriate use and effectiveness of cooling strategies, and increasing their availability in tournaments.

All-solid-state continuous-wave mode-locked Er:Lu2O3 laser at 3 µm

In this paper, we demonstrated stable continuous-wave passively mode-locked operation of an Er:Lu2O3 laser at 3 µm, utilizing a semiconductor saturable absorber mirror (SESAM). By operating the laser in a dry nitrogen environment and utilizing a thermoelectric cooler (TEC) temperature control device to mitigate the thermal effects of Er:Lu2O3 and enhance laser stability, we further compensated for group delay dispersion within the laser cavity through chirped mirrors, an shortest pulse duration of 12.0 ps at a average output power of 150 mW was achieved, which occurred at a center wavelength of 2844 nm, and a pulse repetition rate of 83.5 MHz. Additionally, we achieved a maximum continuous-wave mode-locked output power of 213 mW at an absorbed pump power of 8.3 W, equivalent to a pulse energy of 1.3 nJ. The RF spectrum analysis of the pulse train indicated a high SNR of nearly 70 dB, signifying excellent stability. To the best of our knowledge, This is the first report on the realization of an ultrashort pulse width mode-locked Er:Lu2O3 laser in the mid-infrared band.

Long-term potato response to different irrigation scheduling methods using saline water in an arid environment

Crops’ water requirement is generally higher than the annual average precipitation in arid environments characterized by scarce freshwater resources. While using saline water for irrigation can help sustain agriculture in water-stressed regions, several challenges arises concerning productivity and soil salinization. However, adoption of efficient irrigation techniques such as drip irrigation, irrigation scheduling, and deficit irrigation can help optimize water productivity and mitigate salinity problems in irrigated agriculture. In southern Tunisia, potato is considered among the main cultivated horticultural crops due to its high economic value while it is considered as a crop sensitive to salinity. This crop (cv. Spunta) was the subject of long-term studies (2002–2020) conducted during the fall period in the arid region of Médenine. The crop response to full and deficit irrigation with saline water was assessed for several seasons under contrasting climatic conditions. Scheduling using the soil water balance (SWB) method consisted of the total and/or partial replacement of accumulated crop evapotranspiration (ETc), as derived from climatic data and crop coefficients. The impact of decreasing amounts of irrigation waters on crop yield and soil salinity with waters having a salinity ranging between 3 and 7 dS m−1 was evaluated. Results showed improvements in yield (30% to 37%) obtained with the SWB strategy under actual farming conditions, supporting the use of this strategy for irrigation. Appropriate scheduling also seems to be a key element in saving water (15%–22%) and in reducing risks of soil salinization. In the dry environment of southern Tunisia, optimum supply seems to correspond to a replacement of 100% to approximately 70%–80% of ETc. Applying such irrigation levels resulted in a lower salinity buildup in the root zone and higher crop water productivity. Natural salt leaching seems to be more effective under a more humid soil profile. Yield decreases and soil salinity increases almost linearly (r2 = 0.60) with decreasing irrigation water amounts. Future work should focus on the integration of management practices when using saline water. Investigating the relationship and interaction between irrigation amounts, cultivar, fertilizer supply, and salt leaching will help in resolving productivity and environmental issues.

Investigation on the influence of the slip at the wheel-rail contact patch on the shakedown limit of rail material

Research on factors affecting rolling contact fatigue (RCF) damage of rail materials has become increasingly important since developing effective measures to mitigate RCF damage is crucial. This study focuses on exploring the influence of full slip and partial slip contact modes at the wheel-rail contact patch on the RCF damage behavior and the shakedown limit of the pearlite rail material through wheel-rail RCF rolling-sliding tests. Firstly, based on the wheel-rail adhesion-creep curves in dry, water and oil environments, the creepage required to achieve full slip during the rolling-sliding tests was determined. Then, rolling-sliding tests under full slip contact with different adhesion coefficients were carried out in a dry atmosphere and with the assistance of a third body medium (i.e., oil and water), respectively. Meanwhile, rolling-sliding tests under partial slip contact with the similar contact parameters were performed in a dry atmosphere. The results indicated that RCF damage and wear rates of the rail material under a full slip contact with an adhesion coefficient below the saturation peak on the adhesion-creep curve were significantly less than those under partial slip contact with similar contact parameters. Moreover, under full slip contact with an adhesion coefficient below the saturation peak on the adhesion-creep curve, the pearlite rail materials could exhibit a higher shakedown limit. Furthermore, the influence of full slip and partial slip contact on wheel-rail contact behavior was further analyzed using finite element simulations. Finally, a novel friction modification strategy to mitigate RCF damage and wear of rails was proposed. By applying a specific low-coefficient friction modifier to the wheel-rail interface, the operation of powered wheelsets under controlled creepage conditions that reach the threshold of full slip contact at the wheel-rail contact interface could be employed to achieve the desired adhesion coefficient. Thus, this approach could ensure that the achieved adhesion coefficient met the on-site target adhesion force while reducing RCF damage and wear of rail materials.

Ecological networks in savannas reflect different levels of hydric stress in adjacent palm swamp forest ecosystems.

Palm swamp forests are wetland ecosystems typical of the Brazilian Cerrado, which in recent decades have undergone intense changes due to land use alterations and climate change. As a result of these disturbances, many palm swamps have been experiencing significant drying, which can also affect adjacent vegetation. In the present study, we evaluated whether the drying of palm swamps affects the structure of plant-herbivore networks located in adjacent savanna areas in Brazil. Our results show that savanna areas adjacent to dry zones of palm swamps have fewer interactions, fewer interacting species, and a less specialized topology, which corroborates our expectations. Our findings indicate that the drying of palm swamps also has propagated impacts on adjacent savanna vegetation, impairing more specialized interactions in these environments. On the other hand, contrary to expectations, plant-herbivore networks in dry zones displayed higher modularity, lower nestedness and lower robustness than those in wet zones, suggesting that in dry environments, species tend to compartmentalize their interactions, even with lower interaction specialization. This is the first study to investigate the impacts of environmental drying on the structure of plant-herbivore networks in tropical ecosystems, highlighting the complexity of these effects and their differential impact on specialized and generalized interactions. Understanding these dynamics is crucial for developing effective conservation and management strategies in the face of ongoing environmental changes.

What do frog calls tell us about males? The advertisement call of Physalaemus albifrons (Amphibia: Leptodactylidae) in the Brazilian semiarid region does not reflect either gonadal investment or energy storage

ABSTRACT Anuran advertisement calls can provide accurate information on the reproductive quality of the male callers, thus providing females with indicators for the selection of mates. Body size is generally correlated with the dominant frequency of male advertisement calls. However, it is unclear whether and to what extent call parameters are associated with gonadal investment and the energy reserves of the males. Given that in tropical seasonally dry environments the wet season is very short, gathering information about gonadal investment and energy reserves of mates should be particularly important. In the present study, we evaluated the relationship between acoustic performance, gonadal condition, and fat storage in the Neotropical frog Physalaemus albifrons from the Brazilian semiarid region, testing the hypothesis that the advertisement call (repetition rate, call duration, and fundamental and dominant frequencies) would be a good predictor of male quality in terms of gonadal investment (testicle length) and energy reserves (mass of fat bodies). Contrary to our predictions, neither testicle length nor the mass of fat bodies was related to any of the acoustic parameters of the advertisement calls of P. albifrons. These results indicate that the advertisement call of P. albifrons does not provide reliable information on gonadal investment or energy storage of males. Possibly, in habitats with little and unpredictable rainfall, males of P. albifrons should present small variation in gonadal and fat storage conditions during its short reproductive window. Our findings contribute to the understanding of anuran reproductive strategies in seasonally dry environments.