Effective Surface Research Articles

Tool life improvement for stamping dies in the coining process

ABSTRACT High temperature and high-speed pressing in minting operations lead to the failure of coin-stamping dies. As a result, new coining tools were required more frequently leading to lower operational productivity and higher production costs. This research has examined the effects of materials and surface coating selections on the tool life of the stamping dies in the coining process. The aim of this research was to explore the possibility of extending the tool life of stamping dies. The three kinds of materials under study were alloy tool steel, cold working tool steel, and hot working tool steel. Additionally, Titanium Nitride (TiN) and Chromium Nitride (CrN) surface coating materials using the Physical Vapour Deposition (PVD) process were investigated. The experiment results revealed that the hot working steel yielded the highest tool life of up to 1,300,000 coins, followed by cold working steel at 900,000 coins, and alloy tool steel at 600,000 coins. The CrN PVD coating provided up to more than 400,000 coins compared to TiN PVD coating on hot working tool steel.

The Effect of a Synthetic-Grass Sport Surface on Physiology and Perception During Intermittent Exercise in Hot Conditions.

The current study aimed to determine the effect of a synthetic-grass sport surface on core body temperature, skin temperature, heart rate, thermal sensation, thermal comfort, and rating of perceived exertion (RPE)during intermittent exercise in hot conditions. Using a randomized crossover design, 13 trained/developmental team-sport athletes completed two 50-minute standardized intermittent running protocols on a synthetic and anatural-grass surface, on separate days (control-condition air temperature 32.6 °C [1.3 °C], relative humidity 43.2% [5.3%]). Final skin temperature was significantly higher on synthetic compared with natural grass at the calf (40.1 °C [2.5 °C] vs 33.4 °C [0.6 °C]; P < .001), shoulder (36.6 °C [1.7 °C] vs 33.7 °C [0.7 °C]; P < .001), and chest (33.2 °C [1.1 °C] vs 31.8 °C [1.2 °C]; P = .02). Thermal sensation (median: 2.3; interquartile range [0.5] vs 2.2 [0.5], P = .03) and sweat rate (1.5 [0.4]L·h-1 vs 1.2 [0.3]L·h-1; P = .02) were also significantly higher on synthetic grass. While final core body temperature was significantly higher on the natural than synthetic grass (38.4 °C [0.3 °C] vs 38.2 °C [0.4 °C]),there were no significant differences in delta core temperature, as well as heart rate, thermal comfort, or RPE. Higher skin temperatures, thermal sensation, and sweat rates suggest that exercising on synthetic grass in hot conditions may increase some markers of heat strain during exercise. However, delta core body temperature, heart rate, thermal comfort, and RPE remained unaffected.

A very simple synthesis of defect-rich PdAg nanosponges for highly selective hydrogenation of furfural

Furfuryl alcohol (FA) is an important chemical and has extensive applications in varied fields. To realize the highly selective hydrogenation of furfural (FF) to produce FA, the key is the preparation of the catalysts with excellent performance. Herein, a very simple wet chemical method is developed for the one-step preparation of PdAg nanosponges (NSs). Specifically, with Pd(OAc)2 and AgNO3 as precursors, and ethylene glycol (EG) as both solvent and reducing agent, PdAg NSs can be grown and assembled at mild temperature of 40 °C. Throughout the reaction, no any surfactants and additional reducing agents are applied. The as-prepared PdAg NSs possess 3D self-supported alloy structures, “clean” surface, abundant pores, high specific surface area and rich defects. In the FF hydrogenation reaction at 60 °C under 1.5 MPa H2 pressure in the mixed solvent of ethanol and water (1 : 4 in volume ratio), the self-supported PdAg-1 NSs (1 : 1 in Pd/Ag molar ratio) exhibit superior catalytic performance than other PdAg NSs, pure Pd sample and commercial Pd/C (10%). With PdAg-1 NSs as catalyst in the absence of support, 100% FF can be converted and the selectivity toward FA is as high as 97.1% at 36.0 h of reaction. After 4 cycles, PdAg-1 NSs still maintain the high catalytic activity in FF hydrogenation and high selectivity toward FA, which may originate from the 3D self-supported structures, high specific surface area, “clean” surface, rich defects and electronic synergistic effect between Pd and Ag. This simple fabrication of PdAg NSs introduces new ideas for the synthesis of other nanostructured bi- and multi-metallic catalysts for highly selective FF hydrogenation to FA and other advanced applications.

Practical 6-DoF Manoeuvring Simulation of a BB2 Submarine Near the Free Surface

It is necessary to predict the manoeuvring performance of a submarine accurately at the early design stage for its safe and effective operations. In this paper, the practical 6-DoF simulation models of an X-form stern plane submarine operating near the free surface are proposed. A 1/15 scaled model of ‘BB2 submarine’ is constructed, the captive model tests are performed in a towing tank of Korea Research Institute of Ships and Ocean Engineering (KRISO) at the full-scale depths, 30, 15.4 (snorkel depth), and 4.5 metres (surfaced depth). Resistance and propulsion tests are performed at the deepest depth, 30 metres. The vertical planar motion mechanism (PMM) tests including the forced rolling motions are also carried out at the depth of 30 metres. The horizontal PMM tests are conducted at three kinds of depths, respectively. The depth-varying horizontal plane coefficients in the model are identified, and the coefficients which are little influenced by the depths are treated as the constant values for the practical purpose. Some of velocity coupled terms are approximated by using the added mass coefficients on the assumption that the viscous components are negligible. In addition, the resistance increases, vertical suction forces and moments are measured in the straight-ahead tests with varying the submergence depths. The free surface effects are considered as the exponential function terms in the proposed models. Based on the present tests and the previous studies about the free surface effects on the submerged bodies, it is practically assumed that the free surface effects are exponentially decayed with the depths, and are already negligible when the submergence depth is 30 metres, approximately three times the hull depth. Horizontal and vertical plane manoeuvring motions as well as the neutral flights are simulated with the control plane deflections less than 15 degrees. The present simulations are in good agreements with existing free-running model test results.

Size-dependent thermoelastic dissipation and frequency shift in micro/nano cylindrical shell based on surface effect and dual-phase lag heat conduction model

Size-dependent thermoelastic dissipation and frequency shift in micro/nano cylindrical shell based on surface effect and dual-phase lag heat conduction model

Surface Defects Control Bulk Carrier Densities in Polycrystalline Pb-Halide Perovskites.

The (opto)electronic behavior of semiconductors depends on their (quasi-)free electronic carrier densities. These are regulated by semiconductor doping, i.e., controlled "electronic contamination". For metal halide perovskites (HaPs), the functional materials in several device types, which already challenge some of the understanding of semiconductor properties, this study shows that doping type, density and properties derived from these, are to a first approximation controlled via their surfaces. This effect, relevant to all semiconductors, and already found for some, is very evident for lead (Pb)-HaPs because of their intrinsically low electrically active bulk and surface defect densities. Volume carrier densities for most polycrystalline Pb-HaP films (<1µm grain diameter) are below those resulting from even < 0.1% of surface sites being electrically active defects. This implies and is consistent with interfacial defects controlling HaP devices in multi-layered structures with most of the action at the two HaP interfaces. Surface and interface passivation effects on bulk electrical properties are relevant to all semiconductors and are crucial for developing those used today. However, because bulk dopant introduction in HaPs at controlled ppm levels for electronic-relevant carrier densities is so difficult, passivation effects are vastly more critical and dominate, to first approximation, their optoelectronic characteristics in devices.

Experimental Study on Mechanical Properties and Stability of Marine Dredged Mud with Improvement by Waste Steel Slag

As marine-dredged mud and waste steel slag in coastal port cities continue to soar, the traditional treatment method of land stockpiling has caused ecological problems. Thus, it is necessary to find a large-scale resource-comprehensive utilization method for dredged mud and waste steel slag. This study uses waste steel slag and composite solidifying agents (cement, lime, fly ash) to physically and chemically improve marine-dredged mud. The physical improvement effect of the particle size and dosage of waste steel slag was studied by the shear strength test under the effect of freeze–thaw cycle. Then, based on the Box–Behnken design of the response surface method, the interaction effects of the solidifying agent components on the unconfined compressive strength were studied. Then, the water stability under dry–wet cycles and a microscopic mechanism were analyzed by XRD and SEM tests. The results show that the waste steel slag with a dosage of 30% and a particle size of 1.18~2.36 mm has the best improvement. The interaction between cement and lime and lime and fly ash has a significant effect on the linear effect and surface effect of 7d unconfined compressive strength, and the strength increases first and then decreases with the increase in its dosage. For the 14d unconfined compressive strength, only the interaction between cement and lime is still significant. The unconfined compressive strength prediction model is established to optimize the mix ratio of the composite solidifying agent. In the water stability, the water stability coefficients of the 7d and 14d tests are 0.68 and 0.95, respectively, and the volume and mass loss rates are all below 1.5%, showing a good performance in dry–wet resistance and durability. Microscopic mechanism analysis shows that waste steel slag provides an ‘anchoring surface’ as a skeleton, which improves the pore structure of dredged mud, and the hydration products generated by the solidifying agent play a role in filling and cementation. The results of the study can provide an experimental and technical basis for the resource engineering of marine-dredged mud and waste steel slag, helping the construction of green low-carbon and resource-saving ports.

Antimicrobial surface coating in the emergency department as protective technology for infection control (ASEPTIC): a pilot randomized controlled trial

Study objectiveWe examined the effectiveness of an antimicrobial surface coating for continual disinfection of high touch-frequency surfaces in the emergency department (ED).MethodsFollowing a preliminary observation identifying stretcher rails as the surface with highest touch-frequency in the ED, we conducted a pilot randomized controlled trial involving 96 stretcher rails. The stretchers were randomized to receive an antimicrobial surface coating or placebo coating. Routine cleaning of stretchers subsequently continued as per hospital protocol in both arms. Sampling for total aerobic, gram-positive halophilic, gram-negative and methicillin-resistant Staphylococcus aureus bacteria was performed pre- and post-treatment at 24 h, 7 days and 180 days. Individuals who applied the coating and outcome assessors were blinded to the allocated arms. The primary outcome is contamination of antimicrobial versus placebo rails measured as colony forming units per cm2(CFU/cm2).ResultsBaseline total aerobic bacteria was comparable between placebo and intervention arms (0.84 versus 1.32 CFU/cm2, P = 0.235). Total aerobic bacteria contamination was significantly lower on antimicrobial versus placebo rails at 24 h (0.61 versus 1.01 CFU/cm2, median difference 0.40 CFU/cm2, 95% confidence interval [CI] 0.01 to 1.01 CFU/cm2). There was a non-statistically significant tendency for contamination to be lower on antimicrobial versus placebo rails at 7 days (1.15 versus 1.50 CFU/cm2, median difference 0.35 CFU/cm2, 95% CI -0.64 to 1.28 CFU/cm2), but higher at 180 days (2.06 versus 1.84 CFU/cm2, median difference − 0.22 CFU/cm2, 95% CI -1.19 to 0.78 CFU/cm2).ConclusionThis is the first double-blinded, placebo-controlled, randomized trial to evaluate an antimicrobial surface coating on high touch-frequency surfaces in the emergency department. Total aerobic bacteria found on antimicrobial-coated patient transport stretcher rails was significantly lower than placebo rails at 24 h.

Modeling of elastic plastic deformation of near-surface layers of materials

According to the results of strain measurements, a kinematically hardening body model is used to describe the process of elastic-plastic deformation of 1X18H9T steel. Special attention is paid to the processes occurring in the surface layers. The model takes into account the increasing tightness of shear deformations deep into the material. The increase in the stress of the plastic flow in depth is described by a second-order polynomial. The main parameters of the surface effect were determined experimentally and by calculations using the method of reduction coefficients in the process of successive approximations: depth, coefficient of hardening of the material, stresses of plastic flow on the surface and inside the material. It is shown that in order to study the near-surface effect by the strain gauge method, it is necessary to give preference to bending tests of samples rather than stretching. The presence of the surface effect explains the following facts: the destruction of the sample during the tensile test does not begin from the surface, but from the inside, the origin of fatigue cracks occurs under the surface, the surface effect practically does not affect the deformed state of the elastic body, but very strongly affects the stress state at the surface.

Incorporation of Multiple Binding Sites into an Adaptive MOF for Sieving Butane Isomers

AbstractEfficient separation of liner alkanes from branched alkanes is of prime importance in the petrochemical industry. Herein an adaptive metal‐organic framework FJI‐H38 is reported with 1D channel which can vary delicately ≈4.0 Å. The activated FJI‐H38 displays extremely large butane (n‐C4H10) capacity, especially at low pressure (44.15 cm3 g−1 at 298 K and 0.1 bar), but barely adsorbs isobutane (iso‐C4H10). Remarkably, FJI‐H38 possesses a high n‐C4H10/iso‐C4H10 selectivity of 246.75. Gas‐loaded single crystal X‐ray analysis and modeling calculation reveal that the synergetic effect of pore confinement and surfaces decorated with uncoordinated carboxyl group plays a critical role in the capture of the relatively smaller n‐C4H10 while the exclusion of the larger iso‐C4H10. In addition, dynamic breakthrough tests explicitly prove FJI‐H38 displays prominent separation performance for n/iso‐C4H10 under various conditions with ultra‐high productivity of high‐purity n‐C4H10 (42.48 L/kg, ≥99.0%) and iso‐C4H10 (42.35 L/kg, ≥99.95%).

Investigation of static buckling and bending of nanoplates made of new functionally graded materials considering surface effects on an elastic foundation

Investigation of static buckling and bending of nanoplates made of new functionally graded materials considering surface effects on an elastic foundation

Conjugate heat transfer effects of tri-periodic minimal surfaces on cooling performance in turbine internal cooling channels

As the cooling potential of traditional cooling structures diminishes and turbine inlet temperature rise, there is an urgent need to develop new, efficient cooling designs to reduce the target surface temperature. Triply Periodic Minimal Surface (TPMS) configurations have attracted significant attention due to their unique geometric properties and superior heat transfer performance. This study employs a conjugate heat transfer numerical method to evaluate the heat transfer performance of TPMS configurations compared to traditional pin fins across a Reynolds number range of 2500–20,000. The results indicate that compared to the traditional pin-fin structure, TPMS configurations have a higher overall cooling efficiency under the same pressure loss. Moreover, the rate of improvement in heat transfer performance for TPMS configurations accelerates with increasing Reynolds numbers, meaning that TPMS configurations significantly enhance the overall cooling effectiveness of the system, with improvements ranging from 12.71 % to 51.46 %. The paper further investigates the impact of different TPMS configurations on overall cooling effectiveness. The TPMS-Horizontal configuration demonstrates 1.38 % to 3.44 % higher cooling effectiveness than the TPMS-Vertical configuration under identical boundary conditions, but it requires a greater pressure loss. After accounting for pressure loss, the vertical configuration demonstrates superior overall performance. Overall, the TPMS configuration is significantly superior to the traditional pin-fin structure, possessing substantial cooling potential and research value.

Scale-Dependent Effects of Urban Canopy Cover, Canopy Volume, and Impervious Surfaces on Near-Surface Air Temperature in a Mid-Sized City

Cities are significantly warmer than their surrounding rural environments. Known as the ‘urban heat island effect’, it can affect the health of urban residents and lead to increased energy use, public health impacts, and damage to infrastructure. Although this effect is extensively researched, less is known about how landscape characteristics within cities affect local temperature variation. This study examined how tree canopy cover, canopy volume, and impervious surface cover affect daytime near-surface air temperature, and how these effects vary between different scales of analysis (10, 30, 60, 90 m radii), ranging from approximate street corridor to city block size. Temperature data were obtained from a car-mounted sensor, with traverse data points recorded during morning, afternoon, and evening times, plotted throughout the city of Portland, OR. The variability in near-surface air temperature was over 10° F during each traverse period. The results indicate that near-surface air temperature increased linearly with impervious surface cover and decreased linearly with tree canopy cover, with canopy volume reducing the temperature by 1° F for every 500 cubic feet of canopy volume for evening temperatures. The magnitude of the effect of tree canopy increased with spatial scale, with 60 and 90 m scales having the greatest measurable effect. Canopy volume had a positive relationship on presumed nighttime and early-morning temperatures at 60 and 90 m scales, potentially due to the impacts of wind fluctuation and air roughness. Canopy cover still contributed the largest overall decrease in street-scale temperatures. Increasing tree canopy cover and volume effectively explained the lower daytime and evening temperatures, while reducing impervious surface cover remains critical for reducing morning and presumed nighttime urban heat. The results may inform strategies for urban foresters and planners in managing urban land cover and tree planting patterns to build increased resiliency towards moderating urban temperature under warming climate conditions.

Antibacterial Materials: Influence of the Type and Conditions of Biological Tests on the Measured Antibacterial Activity.

In recent years, the growing problem of antibiotic resistance has highlighted the need for antibacterial materials to prevent the development of infections. Different types of tests exist to certify the antibacterial properties of materials. Variations in results can occur due to the unique requirements of each test technique. The antibacterial test result may be influenced, in particular, by the distinct modes of action of leaching and non-leaching compounds. Using antibacterial materials prepared by the dispersion of an amphiphilic cationic synthetic copolymer in a polyurethane matrix, the influence of the reaction medium and the contact time on the results obtained by two well-established tests: ISO 22196 and CERTIKA is investigated. This shows that the kinetics of killing is bacteria dependent and depending on the test conditions (concentration of salt, time of contact, or media), contradictory results could be obtained. Moreover, the influence of the ionic strength (called salt effect) in both free solution and antibacterial surface is highlighted.

Two-Phase Flow Modelling Based on Roughness Surface Effect of Roller Compacted Concrete

One of the most important considerations that are interest to researchers on the stepped spillway in hydraulic structure is the location of the point at which the flow begins to transform into two phase-flow and the development of boundary layers. In this study, an unconventional rough surface was used (RCC materials), which has completely different properties from what is used in previous laboratory studies, which uses smooth surfaces in reality to represent the actual roughness of the surface. Benchmark mixes are evaluated as a reference standard concrete to determine the optimal combination proportions for RCC according to The U.S. Army Corps of Engineers Standard. A laboratory study of different models enhanced by a mathematical model CFD with VOF technics to described the two- phase interaction to investigate the location of the inception point and compare the results with the proposed equations assumed by different researchers in this topic. The results obtained from the study showed a clear effect of surface roughness on the location of the inception point and the formation of the boundary layer for laboratory models. It’s clearly found that the two-phase flow starts with closer locations than it is for conventional models and the ratios vary (10 % - 20 %) according to the discharge values (where the effect of surface roughness is evident in the low discharges compared to the high discharges in which the boundary Lear effect begins to fade.

Effect of Enamel Surface Coating on Staining Capability Due to Iron-Containing Supplements on Primary Teeth: An in Vitro Study

ABSTRACT Background: The staining of primary teeth due to iron-containing supplements is a common concern among parents and healthcare providers. Materials and Methods: Forty extracted primary teeth were divided into two groups of 20 each. Group A served as the control and received no enamel coating, while Group B was treated with a commercially available enamel surface coating. Both groups were then exposed to iron-containing supplements for 7 days. The teeth were assessed for color changes using a spectrophotometer before and after exposure. The degree of staining was quantified using the CIELAB color space values, specifically the ΔE* value, which indicates the change in color. Results: The mean ΔE* value in Group A (control) was 12.5 ± 1.8, indicating significant staining. In contrast, Group B (coated) showed a mean ΔE* value of 4.2 ± 1.1, reflecting minimal staining. The difference between the two groups was statistically significant (P &lt; 0.001), demonstrating the effectiveness of the enamel surface coating in reducing staining caused by iron supplements. Conclusion: Enamel surface coatings significantly reduce the staining effect of iron-containing supplements on primary teeth.

CFD Analysis of Takeoff from a Water Surface for an Insect-Scale Aerial/Aquatic Robot

To develop an insect-scale aerial/aquatic robot, we analyzed takeoff mechanisms to counteract surface tension, such as paddling, slapping, and clap-and-fling. Because a diving beetle, Eretes griseus, takes off directly from the water surface, a flapping-wing robot is promising as an alternative to a drone with multiple rotary wings. In this study, we first investigated diving beetle flight with a three-dimensional high-speed camera system and analyzed the motion characteristics. Subsequently, we developed a computational fluid dynamics method that tracked the water surface using a volume of fluid method, reproduced the motion with a multibody model, treated the deformation of the elastic membrane wing with the phase delay of the joint angle functions, and simulated takeoff, that is, the transition from water to air, and hovering near the water surface. The simulation result showed that during the transition, the slapping motion exerted the maximum and average lift per unit of body weight of 18 and 9.2, respectively, while those of paddling produced 0.46 and 0.23, respectively. The water surface effect improved the lift by 25% at the normalized height of less than 0.44 and disappeared at a height greater than 0.7. During hovering, while the clap-and-fling motion improved lift by 2.6% and the water surface effect was 9.8%, the synergy effect was 22%. In addition, the former enhanced it significantly after the fling, while the latter was remarkable during the wing acceleration phase. In contrast to ground effects, flapping reduced the water level and caused the ripples, dynamically changing the water surface effect.

Anticancer effect of surface functionalized nano titanium dioxide with 5‐fluorouracil on oral cancer cell line—An in vitro study

Anticancer effect of surface functionalized nano titanium dioxide with 5‐fluorouracil on oral cancer cell line—An in vitro study

Synthesis of silica-coated polygonal Fe3O4 nanoparticles

The small size, surface effect, and tunneling effect of nanomaterials enable their applications in various fields, including catalysis, sensing. Fe3O4 has been widely used in nanotechnology owing to its excellent photoelectromagnetic properties. In this study, polygonal Fe3O4 nanoparticles were prepared through a high-temperature synthesis method. Subsequently, silica coating was applied via the Stöber method to obtain a nanomaterial with uniform particles. The prepared Fe3O4 exhibited a distinct crystal structure and an ultra-high saturation magnetization, reaching up to 134.2 emu/g. Moreover, the dodecyl trimethyl ammonium bromide (DTAB) templating agent facilitated the coating of Fe3O4 with silica. The coated Fe3O4@SiO2 particles featured a well-defined core–shell structure and corrosion resistance, making them highly promising candidates for magnetic targeting medical tools, magnetic resonance imaging agents and other biological applications.

Curcumin-loaded zein nanoparticles: A quality by design approach for enhanced drug delivery and cytotoxicity against cancer cells

Zein, a maize protein, has been explored for constructing potential biomaterial due to its hydrophobic nature, self-assembly capability, and biocompatibility. In its nanoparticulate form, zein is a promising material for drug delivery applications, particularly in cancer treatment. Despite the importance of colloidal stability for effective drug delivery, systematic studies investigating the effect of various surface modifying agents (MAs) on the zein nanoparticles (ZNPs)-based formulations are limited. This study employs quality-by-design (QbD) approach to optimize curcumin-loaded ZNPs, enhancing colloidal stability, size, and drug-encapsulation efficiency using different MAs for potential cancer therapy. Gum arabic (GA) emerged as the optimal stabilizer, with GA-stabilized curcumin-loaded ZNPs (GA-Cur-ZNPs) achieving a particle size of 184.8 ± 2.85 nm, zeta potential of −23.4 ± 0.56 mV and 87.1 ±1.55 % drug encapsulation efficiency, along with excellent colloidal stability over two months. The optimal formulation also demonstrated sustained release of Cur over 72 h. GA-Cur-ZNPs demonstrated lower IC50 values and higher anti-proliferative effects on three different cancer cell lines compared to the free drug, while also exhibiting superior intracellular uptake. With negligible toxicity to human dermal fibroblast cells, the optimized Cur-GA-ZNPs show promise for safe and effective killing of cancer cells.