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Effect of iron oxidation state on the catalytic performance of Fe/C in liquid phase flow hydrogenation of 2-butyne-1,4-diol

Cis-2-butene-1,4-diol and 1,4-butanediol are crucial precursors in producing bioplastics and biodegradable plastics. Moreover, cis-2-butene-1,4-diol is used in the production of vitamins A and B6, fungicides and insecticides. On an industrial scale, they are produced by hydrogenation of 2-butyne-1,4-diol with Ni Raney as catalyst at > 160 °C and > 15 MPa. Herein, the effect of mesoporous carbon, iron loading (2, 6, 10 and 14 wt%), and metal oxidation state on the activity and selectivity of iron catalysts in the liquid phase continuous flow 2-butyne-1,4-diol hydrogenation at mild conditions (at temperature range 10–65 °C and pressure range 1–20 bar) was performed. Catalytic investigations supported by statistical modeling and physicochemical characterization (TPR, H2-TPD, physisorption, TEM, XPS, and Mössbauer spectroscopy), showed that the activity of the Fe/C can be determined by the presence of functional groups in mesoporous support which are responsible for high metal dispersion and strong metal-support interaction, which boosts the catalytic activity of iron catalysts. Additionally, the formation of metastable iron carbides which are active in hydrogenation cannot be excluded. All of the catalysts showed 100% selectivity toward cis-2-butene-1,4-diol at the lowest temperature. However, the best compromise between selectivity and activity (TOF=336 h−1) was achieved with 2 wt% Fe at 1 bar and 25 °C.

Influence of carbon percentage on the wear and friction characteristics of ATOMET 4601 alloys in heavy-duty machinery

Heavy-duty machinery demands materials with strong wear resistance and good frictional properties, which conventional materials often lack. The knowledge of PM alloys’ friction and wear characteristics versus standard steel materials is limited. ATOMET 4601, a high-strength prealloyed powder with excellent compressibility, allows for parts with densities over 6.8 g/cm³. Carbon (0, 0.5, 1.0 wt.%) was added to enhance performance. These alloys, compacted to 75% of theoretical density and sintered at 1100 ± 10°C, were tested for wear and friction against EN31 steel. Results showed carbon improved tribological performance, with ATOMET 4601 + 1.0%C exhibiting the best wear resistance. Regression models and interaction plots indicated significant effects of load and speed on wear rate and coefficient of friction. Microstructural analysis revealed carbides and oxides in the ferrite matrix, with adhesive, abrasive, and oxidative wear as primary mechanisms.

A comparative study of low cyclic loading effects on plastic strain, nonlinear damping, and strength softening in fiber-reinforced recycled aggregate concrete

The incorporation of fibers significantly enhances the properties and structural performance of recycled aggregate concrete. This study introduces Fiber-Reinforced Recycled Aggregate Concrete (FRAC) by integrating steel fibers (SF) and polypropylene fibers (PPF) into the recycled aggregate concrete (RAC) matrix. A comprehensive series of cyclic loading tests, including reload and unload sequences, were conducted to meticulously analyze the deterioration of strength and energy dissipation capabilities of SF/PPF-reinforced RAC. The research examines the effects of fiber characteristics, volume ratios, lengths, and diameters on strength degradation after the peak stress along the stress-strain curve. Degradation models based on plastic strain were proposed for both SF-reinforced RAC and PPF-reinforced RAC. The study further investigates the fluctuation of strain energy in FRAC under low cyclic loading, revealing the correlation between plastic strain energy and equivalent viscous damping ratio. A nonlinear viscous damping model that accounts for the influence of the reinforcing index (RI) is proposed. This model effectively predicts the degradation of strength, the evolution of plastic strain, and the dynamics of nonlinear viscous damping in composite materials with varying fiber content. Ultimately, this research provides essential technical insights for the practical engineering application of RAC.

Incipient fault diagnosis for robot manipulators based on evolution of friction characteristics in transmission components

Abstract The tribological behavior can be informative about the incipient faults of robot manipulators. This study explores the evolution of friction characteristics from cold start to thermal equilibrium through a series of steady-state friction experiments. Based on these experimental observations, a friction-based fault diagnosis framework is proposed. The fault diagnosis process primarily involves defining the healthy state, decomposing friction curves and their features, and anomaly detection. Given the dependence of friction characteristics on different sources of faults, the parameters of steady-state experimental friction model are divided into two categories: one associated with contact interactions and the other related to non-contact regimes. Subsequently, confidence regions corresponding to distinguishable friction characteristics are independently constructed. These regions encapsulate the statistical description of the healthy state, characterized by mean values and the covariance of the friction characteristic parameter vectors during the unloaded state. In addition, we conduct experiments that consider the influence of applied loads on friction behavior. These experiments serve as a test set for comparison against nominal statistics. Leveraging the similarity between the effects of wear and load on friction, we introduce equivalent load thresholds to assess the severity of joint degradation. The results demonstrate the feasibility of employing confidence region views based on friction characteristic classification for fault detection and isolation.

Fatigue damage assessment of a large rail-cum-road steel truss-arch bridge using structural health monitoring dynamic data

Structural health monitoring (SHM) system provides valuable information for the fatigue assessment of existing rail-cum-road bridges. This paper aims to develop an effective fatigue assessment approach for the rail-cum-road bridge, Jiujiang Yangtze River Bridge, by utilising the SHM data, focusing on dynamic modal analysis, finite element model updating and fatigue assessment. First, the traffic load spectrum and modal characteristics of the bridge are investigated from the SHM data. A three-dimensional finite element model is constructed and then updated by using the measured modal data through the proposed regularised model updating method. Then, the updated numerical model is verified with the measured dynamic response data, which can be utilised for calculating stress response at critical structural components of the rail-cum-road bridge. Finally, an improved Corten-Dolan’s model is proposed to analyse the fatigue damage and structural reliability of the critical structural components of the bridge, taking into account the combined effects of train and highway vehicle loads. The results demonstrate that the proposed fatigue assessment method provides more reliable results for the rail-cum-road bridge by considering the combined effect of multi-level traffic loads and the non-linear fatigue damage accumulation. It is concluded that the short H-shaped suspender is identified as the most vulnerable structural member of the rail-cum-road bridge, and the remaining fatigue service life of the typical components of the bridge should meet the design requirement.

Impact of variable hydrostatic pressure and intermittent operation on filtration performance and biofouling layer in gravity-driven membrane system for practical decentralized water supply

The gravity-driven membrane (GDM) systems offer a promising solution for decentralized drinking water supply due to its low maintenance and energy consumption. However, research on the practical application of GDM under variable hydrostatic pressure (variable load) and intermittent operation conditions, particularly in response to high-turbidity water, remains limited. This study investigates the long-term performance and characteristics of the biofouling layer of GDM under ultra-low variable hydrostatic pressure (20–60 mbar) and intermittent operation (8–12 h) conditions in practical decentralized water supply. The results indicate that the membrane flux (1.9–6.0 L∙m−2∙h−1, LMH) remained relatively stable despite variations in gravity-driven pressure (ΔP). Long-term operation of GDM can stably remove turbidity and potential pathogens from raw water. The total protein/polysaccharide ratios of extracellular polymeric substances (EPS) in the biofouling layer were below 0.50, reducing contaminant adhesion on the membrane surface. The 0.2–0.4 μm transparent exopolymer particles (TEP) fraction might be crucial for biofouling layer formation. The key species, belong to Proteobacteria and Patescibacteria, significantly alleviated membrane fouling by degrading polysaccharide and proteins in biofouling layer. Comammox Nitrospira were significantly enriched, contributing to efficient nitrification. GDM with variable load maintained a stable flux of 2.2–5.2 LMH under high-turbidity water conditions (300–1200 NTU), and simple forward flushing combined with sludge discharge can quickly restore ΔP. Overall, the variable load GDM system effectively manages membrane fouling and maintains stable filtration performance through the combined effects of variable load and intermittent operation, ensuring long-term and low-maintenance operation for decentralized water supply.

Hybrid finite element modeling of subsurface-originated spalling in flexible bearings with hoop stresses

The flexible bearing in a harmonic reducer undergoes structural deformation after being mounted on the cam, causing the bearing to operate under a complex stress state. A hybrid finite element model is developed to investigate crack initiation and propagation in flexible bearings with hoop stress under rolling contact fatigue loading. The model is coupled with continuum damage mechanics, and the damage evolution equation takes the maximum shear stress amplitude as the damage-causing stress since the hoop stress inevitably affects the fatigue life. The model is verified by comparison with the fatigue life of the inner ring without hoop stress. The crack initiation and spalling formation mechanisms in the inner ring assembled with the cam are analyzed in detail. Moreover, the effects of contact load and equivalent interference on the inner ring’s spalling morphology and fatigue life are studied.

Tribofilm distribution and tribological analysis of piston ring-cylinder liner interfaces under realistic engine conditions

The study investigates tribofilm distribution and tribology performance on piston ring-cylinder liner surfaces under realistic internal combustion (IC) engine conditions. By examining the effects of load, temperature, and oil film thickness ratio, the research reveals that the tribofilm is significantly greater on the cylinder liner surface compared to the piston ring surface. The findings highlight that a specific excitation pressure is necessary for tribofilm formation. An oil film thickness ratio of 1.8041 is evaluated as an accurate boundary for tribofilm distribution on the cylinder liner surface. These insights provide valuable data for designing piston ring-cylinder liner interfaces and improving IC engine performance.

Effect of Lateral Load to the Behavior of Single Piles Subjected to Earthquake Load in Sand

In fact, pile usually carry static and dynamic load in same time, the case of simulations lateral and dynamic load is possible occurred. This case is not cover enough by previous researches especially by laboratory model. Therefore, the purpose of this study is to determine the extent to which altering the horizontal lateral loads impacts the behavior of individual piles during seismic events. An experimental test was devised using a physical model with an advanced shaking table that using El Centro earthquake. Sandy soil with 65% relative density used raining technique. Lateral loads were applied at levels of 0%, 50% and 100% from allowable lateral load capacity. It was observed that when lateral load increased from 0% to 50% and 100%, the lateral displacement response decreased by 32.10% and 49.59% respectively. While the vertical displacement increased by 49.96% and 76.95%. Finally, the acceleration decreased by 34.39% and 41.03%. This is possibly due to the load acts at an angle opposite to the earthquake as a restraining factor for the pile. led to a decrease in lateral displacement, vertical displacement, and peak ground acceleration.

The effect of attentional load on modal and amodal completion

The effect of attentional load on modal and amodal completion

Reducing Viral Load Impact: Blood Transfusions as a Complementary Approach in HIV Treatment

Blood transfusions have traditionally been associated with the management of anemia in individuals living with HIV; however, their potential role as a complementary approach in reducing viral load impact is gaining attention. This review explores how blood transfusions can enhance immune function, improve oxygen delivery, and support the efficacy of antiretroviral therapy (ART), thereby contributing to better health outcomes for patients. By addressing complications associated with HIV, such as anemia and immune dysfunction, blood transfusions may play a crucial role in optimizing treatment strategies and enhancing the overall quality of life for individuals living with the virus. The relationship between viral load and immune function is critical in HIV management, as high viral loads are associated with increased morbidity and mortality. Blood transfusions can mitigate the negative effects of viral load by improving the physiological conditions necessary for an effective immune response. Enhanced oxygenation from transfusions supports immune cell proliferation and activity, potentially leading to better control of viral replication and lower viral load levels. Moreover, improving hemoglobin levels through transfusions can reduce fatigue, increase treatment adherence, and promote active participation in ART. Keywords: anemia, blood transfusions, HIV, immune response, viral load

Oscillating Heat Pipe Start-up and Flow Characteristics with Water as Working Fluid

Thermal management has grown more and more problematic as electronic components continue to get faster and smaller. One of the passive two-phase cooling systems are Oscillating heat pipe (OHP) that have the capacity to transmit a significant quantity of thermal energy across long distances. Oscillating heat pipe is a device that has the potential to satisfy this developing requirement. An investigation into the effects of orientation, filling ratio, and heat load on the initiation and characteristics of oscillatory motion, combining numerical simulations with experimental validation. A copper tube with a 2 mm inner diameter and a 2 mm wall thickness is used to fabricate the OHP. The condenser, evaporator, and adiabatic sections are designed with lengths of 50 mm, 50 mm, and 150 mm, respectively. Results showed that the onset of oscillation occurs more rapidly with increasing input heat flux values compared to lower heat input conditions. The amplitude variations of the temperature of evaporator raised with the raising of heating power. The curves for the higher heat inputs (60 and 80 watts) appear to have higher average evaporator temperatures throughout the test compared to the 40-watt curve. Oscillation movement in tubes is proportional to charge ratio, and it is observed that it rises as charge ratio increases. It demonstrates that in Closed-loop oscillating heat pipe, a sufficient charge ratio is required to maintain the motion of oscillation.

Unraveling the key molecular events of Pinot noir berry ripening under varying crop load

Aligned to exploring the physiological and molecular complexity of grape berry development, there is a need to characterize the influence of the source:sink relationships on the genetic regulation of fruit composition. Crop load, as defined by the amount of fruit produced per unit vegetative growth at dormancy, is a common measure of source:sink relationships used to evaluate vineyard production efficiency. We studied the impact of varying crop load on the transcriptome and metabolome of Pinot noir grape berries by comparing the development and ripening of fruit grown on vines with either 50 % or 75 % of their grape clusters removed immediately following fruit set compared to unthinned vines for three consecutive vintages. A clear impact on the general phenylpropanoid pathway resulting in a redistribution between stilbenes and anthocyanins was revealed under varying crop loads and consistent with the transcriptomic profiles of the corresponding branches. Moreover, we identified genes, such as LBDIa3 and AG2, modulated by crop load around veraison, representing putative transcriptional key triggers of the berry ripening phase responding to differences in the vine source:sink ratio generated by the application of cluster thinning. Genes, specifically EXPA1 and EXPA18, involved in softening and other crucial events of ripening initiation responded to crop load and likely influenced the progression of the ripening process. Beyond the major impacts represented by a shift of the onset and completion of ripening, we were able to highlight more subtle effects of the crop load, related to the rate at which the molecular and metabolic changes occur. This study asserts that grape metabolism and transcriptome are remarkably flexible, and that manipulations such as cluster thinning induce extensive, genome-wide changes in expression during berry development. The insights gained here pave the way to progress towards the construction of robust models depicting the molecular network that characterizes berry development and the impact of crop load on its molecular regulation.

Analysis of concrete damage at anchorage end of the high-speed railway bridge sound barrier under the 400 km/h train-induced wind loads

The sound barrier installed on high-speed railway bridges withstands repeated train-induced wind load, which may lead to concrete damage at its anchorage end. This paper focuses on the assessment of concrete static damage at the sound barrier anchorage end under train-induced wind loads. The nonlinear finite element model of the sound barrier anchorage system is established to analyze the stress distribution, strain distribution and static damage of concrete structure at the anchorage end under 400 km/h train-induced wind loads in respect of different bolt preloads. The simulated results illustrate that both mortar and concrete near bolt holes suffer a certain degree of tensile and compressive damage. The maximum tensile and compressive damage factor values for mortar and concrete are 0.930, 0.643 and 0.892, 0.434 respectively. In addition, the effects of train-induced wind load on the internal force of the sound barrier anchorage take nearly no account, with a maximum of only 0.68 %. The results indicate that bolt preload is the most significant factor for concrete static damage, while the train-induced wind load appears negligible. An appropriate bolt preload can avoid the concrete static damage of the sound barrier anchorage end, and guarantee the structural stability of the sound barrier.

Effects of marine environment and fatigue pre-damage on the residual tensile properties of SFCBs

Steel-fiber reinforced polymer (FRP) composite bars (SFCBs) present a promising solution to corrosion issues associated with conventional reinforcement in marine environments, offering a viable alternative. While the performance of SFCBs under marine environments or fatigue loading is well understood, their behavior under combined conditions remains unreported. This study conducted tension-tension fatigue tests on seawater-immersed SFCBs to assess the effects of fatigue loading (at a stress level of 0.36), various aging temperatures (23°C, 40°C, and 60°C), and durations (30, 180, and 360 days) on their residual properties. Microscopic analysis was used to investigate the degradation mechanisms due to environmental aging. The results indicate that environmental aging deteriorates the GFRP matrix in the outer layer of SFCBs, with fatigue loading further causing matrix cracking and reducing the quasi-static tensile strength. The residual tensile strength of SFCBs decreases with increasing aging times or temperatures, while aging shows no significant effect on their fatigue life. Additionally, a model predicting the residual tensile strength of SFCBs based on damage accumulation was proposed. According to the model, tensile strength initially rapidly decreases with aging time and eventually stabilizes. These findings offer practical insights for the application of SFCBs in concrete structures.

Effect of human-induced dynamic loading and its mitigation on pedestrian steel truss bridges

Effect of human-induced dynamic loading and its mitigation on pedestrian steel truss bridges

MRI-compatible and sensorless haptic feedback for cable-driven medical robotics to perform teleoperated needle-based interventions.

Surgical robotics have demonstrated their significance in assisting physicians during minimally invasive surgery. Especially, the integration of haptic and tactile feedback technologies can enhance the surgeon's performance and overall patient outcomes. However, the current state-of-the-art lacks such interaction feedback opportunities, especially in robotic-assisted interventional magnetic resonance imaging (iMRI), which is gaining importance in clinical practice, specifically for percutaneous needle punctures. The cable-driven 'Micropositioning Robotics for Image-Guided Surgery' (µRIGS) system utilized the back-electromotive force effect of the stepper motor load to measure cable tensile forces without external sensors, employing the TMC5160 motor driver. The aim was to generate a sensorless haptic feedback (SHF) for remote needle advancement, incorporating collision detection and homing capabilities for internal automation processes. Three different phantoms capable of mimicking soft tissue were used to evaluate the difference in force feedback between manual needle puncture and the SHF, both technically and in terms of user experience. The SHF achieved a sampling rate of 800Hz and a mean force resolution of 0.26 ± 0.22N, primarily dependent on motor current and rotation speed, with a mean maximum force of 15N. In most cases, the SHF data aligned with the intended phantom-related force progression. The evaluation of the user study demonstrated no significant differences between the SHF technology and manual puncturing. The presented SHF of the µRIGS system introduced a novel MR-compatible technique to bridge the gap between medical robotics and interaction during real-time needle-based interventions.

Experimental investigation of dynamic drying in single pharmaceutical granules containing acetaminophen or carbamazepine using synchrotron X-ray micro computed tomography

Drying time, velocity, and temperature are important aspects of the drying process for pharmaceutical granules observed during tablet manufacturing. However, the drying mechanism of single granules is often limited to modelling and simulation, with the internal and physical changes difficult to quantify at an experimental level. In this study, in-situ synchrotron-based X-ray imaging techniques were used for the first time to investigate the dynamic drying of single pharmaceutical granules, quantifying internal changes occurring over the drying time. Two commonly used excipients (lactose monohydrate (LMH) and microcrystalline cellulose (MCC)) were used as pure components and binary mixtures with one of either two active pharmaceutical ingredients of differing hydrophilicity/hydrophobicity (acetaminophen (APAP) and carbamazepine (CBZ)). Water was used as a liquid binder to generate single granules of 25 % to 30 % moisture content. Results showed that for most samples, the drying time and composition significantly influences the pore volume evolution and the moisture ratio, with the velocity and temperature of the drying air possessing mixed significance on increasing the rate of pore connectivity and moisture removal depending on the sample composition. Effects of active ingredient loading resulted in minimal influence on the drying of CBZ and generated binary mixtures, with APAP and its respective mixtures’ drying behaviour dominated by the material’s hydrophilic nature.

Investigation of the effect of cefazolin drug on swelling and mechanical and thermal properties of polyacrylamide-hydrogels using molecular dynamics approach

Through molecular dynamics simulations, this study examined the interactions between water and cross-linked hydrogels, with a particular emphasis on the effect of cefazolin drug loading. The swelling percentage, ultimate strength, Young's modulus, heat flux, and thermal conductivity of polyacrylamide-based hydrogels were evaluated in relation to their respective drug concentrations (0 %, 3 %, 5 %, 15 %, and 30 %). The study results show that after 10 ns, the kinetic energy and total energy of atomic specimens stabilized at values of 12,532 and 12,488 kcal/mol, respectively. As the drug ratio increased from 0 to 15 %, the volume of polyacrylamide decreased from 342,722 to 302,583 ų, with further increased from 15 to 30 % reducing the volume to 298,562 ų due to pore and interatomic space closure by the drug. As the drug ratio increased from 0 to 3 %, the ultimate strength of the simulated structure slightly decreased from 0.0333 to 0.0332 MPa, then increased to 0.0333 MPa at a 5 % drug ratio, and remained constant beyond that. The heat flux value decreased from 1583 to 1563 W/m2 with a drug ratio increase from 0 to 3 %, but then increased from 1563 to 1585 W/m2 as the drug ratio further increased to 30 %. Increasing the drug ratio had no effect on the thermal properties of simulated structure, and the thermal conductivity remained constant at 0.57 W/m·K with increasing cefazolin dosage.

Experimental and numerical study of a hinged floating bridge under waves and moving loads

ABSTRACT As an important means of water transportation, floating bridges have broad application prospects. In this paper, a numerical calculation model of the floating bridge considering the combined actions of waves and moving loads is established based on the potential flow theory, and model tests are carried out to verify the accuracy of the numerical method. The effects of motorcade loads and wave parameters on the dynamic responses of the floating bridge were further investigated. The results show that the larger vertical displacements of the floating bridge are affected by both the increase in the number of vehicles and the decrease in vehicle distances. The wave frequency and wave amplitude ranges dominated by the waves and vehicle loads were provided. The extreme dynamic responses of the hinged floating bridge under the combined effect of the waves and moving loads are less than the linear superposition of the individual effect.