Slight Fluctuation Research Articles

Ecological vulnerability assessment and spatial-temporal variations analysis in typical ecologically vulnerable areas of China

Ecological vulnerability assessment is crucial for environment protection, ecological restoration and resource utilization. However, many former studies have limitations in the indicator system of the assessment, which were not comparable for different types of ecologically vulnerable areas. It is difficult to apply directly to the ecological vulnerability assessment of different types and in various regions. Aiming to solve these problems, the study proposed a well-established and comprehensive indicator system for ecological vulnerability assessment and conducted ecological vulnerability assessment application of five types of typical ecologically vulnerable areas of China based on remote sensing, meteorological, geographic and other data. The results show that the average EVIs value of Zhangbei County ranging from 0.525 to 0.559 are the highest among the five research areas during the four periods, followed by Zoige region and Xiamen bay. However, the region with the lowest average EVI value varies. In 2005 and 2015, it was Taihe County, while in 2010 and 2020, it was the Sanjiangyuan region. The variation of average EVIs in the five typical areas presents slight fluctuation and remains generally stable from 2005 to 2020. It indicates that the environmental protection measures and projects undertaken by the Chinese government in recent years have had a striking effect, curbing the trend of ecological environment deterioration.

A single-center study of reference intervals for TAT, PIC, TM and t-PAIC in healthy older Chinese adults

ObjectiveTo explore the distribution of thrombin–antithrombin complex (TAT), plasmin-α2-antiplasmin inhibitor complex (PIC), thrombomodulin (TM), and tissue plasminogen activator-inhibitor complex (t-PAIC) in healthy older Chinese adults, and establish the reference intervals (RIs).MethodsThe Biotech Shine i2900 chemiluminescence immune assay was used to measure the plasma concentrations of TAT, PIC, TM, and t-PAIC in 1628 adults ≥ 60 years. The RIs were established using the 2.5th and 97.5th percentiles of the distribution.ResultsTAT levels were lower in males than females across all ages. Differences between the ages of 60–79 and ≥ 80 in both sex groups were statistically significant, with an upward trend with age. PIC levels showed no difference between the sexes but increased with age in both groups. TM levels did not differ between the sex groups, with slight fluctuation with age. The level in females aged 60–69 was slightly higher than that in the other groups; the difference was statistically significant. T-PAIC levels were not significantly different between the sex groups, with less fluctuation with sex and age. The level in males ≥ 80 years old was slightly lower than that in the other groups; the difference was statistically significant. The RIs for all markers in healthy older Chinese adults were determined and statistically reported by age and sex. For TAT, the RIs for males aged 60–79 and ≥ 80 are 0.51–2.30 ng/mL and 0.88–3.72 ng/mL, respectively, whereas for females aged 60–79 and ≥ 80, the RIs are 0.68–2.82 ng/mL and 1.02–3.67 ng/mL, respectively. For PIC, the RIs for the age groups 60–69, 70–79, and ≥ 80 are 0.10–0.89 µg/mL, 0.12–1.00 µg/mL, and 0.21–1.04 µg/mL, respectively. The RI of TM for females aged 60–69 is 3.32–13.22 TU/mL, whereas it is 2.96–13.26 TU/mL for the other groups. The RI of t-PAIC for males aged ≥ 80 is 1.63–10.68 ng/mL, whereas it is 2.33–11.34 ng/mL for the other groups.ConclusionsDiscrepancies exist in thrombus markers among different sex and age groups. The RIs of TAT, PIC, TM and t-PAIC for healthy older Chinese adults were successfully established.

Investigation of start-up strategies and temperature regulation on enhanced methanogenesis in anaerobic digestion of food waste

Temperature is a crucial parameter for anaerobic digestion of food waste. Thermophilic anaerobic digestion (TAD) exhibits high methane production but has a hard initiation. This study compared two start-up strategies, one-step temperature increase and step-wise temperature increase, for achieving rapid TAD initiation. Compared to the step-wise temperature increase, the one-step temperature increase demonstrated stronger stability with slight pH fluctuation. Thermophilic communities were established more rapidly by the one-step temperature increase. Its substrate degradation was more enhanced through improving carbohydrates and lipid metabolisms than step-wise’s. These indicated one-step temperature increase strategy can initiate TAD efficiently. Additionally, a comparative analysis between TAD and mesophilic anaerobic digestion (MAD) was conducted on multilevels. TAD produced 25.29% more methane than MAD. The increased Defluviitoga and Hydrogenispora in TAD promoted hydrogenotrophic methanogenesis. The enriched genes related to the decomposition of glucose and glycerol resulted in higher substrate hydrolysis, acidogenesis, and acetogenesis in TAD than that in MAD. This study elucidated the full stages of TAD, which strengthened methanogenesis.

Molecular interaction of a protease inhibitor, leupeptin, with human serum albumin: Insights from calorimetry, spectroscopy, microscopy, and computational approaches

Leupeptin (LPN) possesses anti-inflammatory and inhibitory effects on periodontitis and gingivitis, and it also inhibits human coronavirus and SARS-CoV-2 in cells. The characterisation of its interaction with human serum albumin (HSA), the key transport protein in the blood circulation of the human body, contributes essential information to the drug's pharmacokinetic properties. Various techniques, such as isothermal titration calorimetry (ITC), circular dichroism (CD) spectroscopy, atomic force microscopy (AFM), molecular docking, and molecular dynamics simulation (MDS), were employed to characterise the LPN-HSA interaction. The ITC result revealed a moderate binding affinity in the LPN-HSA interaction with a binding constant (Ka) value of 4.27 ± 0.27 × 106 M−1. The thermodynamic analysis indicated that LPN binding to HSA was spontaneous, resulting from a negative Gibbs free energy change (∆G° = − 37.91 ± 0.04 kJ mol−1) and involving an exothermic reaction due to a combination of a negative enthalpy change (∆H° = − 11.4 ± 0.9 kJ mol−1) and a positive entropy change (∆S° = 88.82 ± 3.4 J mol−1K−1). The HSA secondary structure remained unaltered upon the addition of LPN, as evident from the far-UV CD results. AFM results showed HSA morphological changes induced by LPN binding due to the occurrence of aggregates in the LPN-HSA complex. Molecular docking results predicted that LPN preferably binds to site III of HSA, involving hydrogen bonds, electrostatic, van der Waals forces, and hydrophobic forces. The MDS demonstrated a slight deviation and fluctuation, which supported the overall stability of the LPN-HSA system. Thus, these findings provide additional information on the pharmacokinetics of this drug and contribute to designing new drugs for clinical use, particularly those related to inflammatory diseases.

The driving mechanisms of industrial air pollution spatial correlation networks: A case study of 168 Chinese cities

To enhance regional collaborative management and effectively address air pollution, this paper constructs the industrial air pollution network of 168 cities in China between 2010 and 2021. Social network analysis (SNA) and temporal exponential random graph model (TERGM) are used to investigate the structural characteristics and driving mechanisms of industrial air pollution spatial correlation networks. The results indicate the following: (1) Industrial air pollution levels in key Chinese cities showed a slight fluctuation between 2010 and 2015, but decreased after 2015. (2) The industrial air pollution linkage network exhibits small-world characteristics and path dependence, with different cities playing distinct roles in the network. (3) The evolution of the network is influenced by both exogenous and endogenous mechanisms. Local network structures such as reciprocity, connectivity, and transitivity make the network exhibit path-dependent characteristics. Cities’ attributes such as economic development level, green innovation capacity, and population density significantly influenced their status in the network and linkages between cities. Pollution linkages are more likely to occur in cities with similar levels of economic development, green technological innovation capacity, and institutional environments. Therefore, effective regional division for scientific collaborative governance should be considered from multiple perspectives. Based on these results, the paper provides several policy recommendations.

Flow boiling heat transfer characteristics and mechanism analysis of high-pressure water in parallel twin narrow rectangular channels

Experimental investigations on the flow boiling heat transfer characteristics of high-pressure water are carried out in parallel twin narrow rectangular channels. An integrated structure was utilized to define the geometry of the test section in this study. The cross-sectional size of a single channel measures 60 × 2 mm, with an effective heating and flow length of 1450 mm. Experiments encompass a range of pressures 10–16 MPa, mass flux 500–1500 kg m−2·s−1 and heat flux 100–300 kW m−2. First, the heat transfer characteristics in the parallel twin channels are determined. Results show the heat transfer and flow distribution between the twin channels are generally balanced, with only a slight fluctuation observed near the saturation point. Besides, for one narrow rectangular channel, the boiling heat transfer coefficient is found to be essentially affected by the system parameters. The increases in mass flux, heat flux, and pressure will all exert the promotion of boiling enhancement. Among these factors, pressure and heat flux have a relatively more pronounced impact. In addition, heat transfer mechanisms in narrow rectangular channel with a large aspect ratio under high-pressure conditions are analyzed in detail. The transverse buoyancy effect has been identified as a significant factor in the regions of single-phase forced convection and partial subcooled boiling. Once the heat transfer reaches the stage dominated by nucleate boiling, the bubble nucleation and motion behaviors constitute the primary factors of heat transfer enhancement, under the coupling effects of channel structure and high-pressure conditions.

Elucidating the microstructure evolution and performance response of wire-arc directed energy deposited Al–Zn–Mg–Cu alloy at as-deposited and post-processing heat treatment states

Wire-arc directed energy deposition technology was employed to manufacture ultra-high-strength Al–Zn–Mg–Cu alloy taking advantage of variable polarity cold metal transfer (CMT) process. The grain characteristics and precipitation behavior under as-deposited (AD) and post-processing heat treatment (PHT) states were comparatively analyzed. The relationship between the microstructure evolution and mechanical performances was fully disclosed. The obtained results show that the grain structure of AD sample exhibited a nearly fully-equiaxed feature (average size: ∼45 μm), which was caused by the low heat input and variable polarity of CMT advance mode. The microhardness distribution of AD sample consisted of slight fluctuation and stable areas along the building direction due to the different thermal history and precipitation process. After the PHT process, the average grain size and morphology almost remained unchanged. However, compared with the size and type of precipitation phases under the AD state, high-density nanoscale (∼5 nm) metastable η′ phases were precipitated in the grain interior of the PHT sample, which contributed to the crucial precipitation strengthening effect. The homogeneous microhardness distribution was achieved with a high level (∼180 HV0.2). Meanwhile, tensile properties and elongation significantly increased to 524.68 ± 7.31 MPa and 7.10 ± 2.09 % after the PHT process, respectively.

Dynamics of respiratory infectious diseases under rapid urbanization and COVID-19 pandemic in the subcenter of Beijing during 2014–2022

ObjectiveThe study analyzed the impact of urbanization on epidemiological characteristics of respiratory infectious disease in Tongzhou District, Beijing during 2014–2022 to provide reference for prevention and control priorities of respiratory infectious diseases during the innovative urbanization process in China. MethodsThe incidence data of notifiable respiratory infectious diseases (NRIDs) in Tongzhou Beijing during 2014–2022 were summarized. The trend of incidence rate was analyzed by Joinpoint regression model, and entropy method was performed to construct the comprehensive index of urbanization (CIU) and generalized linear model was used to analyze the influence of CIU on the incidence rate of respiratory infectious diseases. ResultsTotally 72616 NRIDs cases were reported in Tongzhou District during 2014–2022, and the incidence rate of NRIDs was higher during 2017–2019 (153/100 000) than during 2014–2016 (930/100 000) and during 2020–2022 (371/100 000), respectively (both P < 0.001). The CIU constantly increased with slight fluctuation in 2016 and 2018, respectively. The incidence rate of NRIDs showed an increase along with the CIU during 2014–2019 (r = 0.95, P = 0.004), while the incidence rate's tendency was interrupted by COVID-19 during 2020 with slight decrease in 2020–2021 and rebounded in 2022. For the patients aged <15 years, the incidence rate of NRIDs revealed a very sharp rise at the urbanization period without COVID-19 pandemic compared with that under pre-urbanization period (RR = 7.93, 95 % CI 7.63−8.24), and dropped off to the similar level as of pre-urbanization period when COVID-19 pandemic spread. ConclusionsUrbanization process may increase the incidence of NRIDs but constrained by COVID-19. Certain measures should be taken to prevent and control the effects by urbanization process, such as good natural environment with less population density, ecological environment with good air quality, promoted hand hygiene, mask wearing, keeping interpersonal distance, vaccination, media publicity for NRIDs’ prevention and control.

Optimizing Driving Parameters of the Jumbo Drill Efficiently with XGBoost-DRWIACO Framework: Applied to Increase the Feed Speed.

The jumbo drill is a commonly used driving equipment in tunnel engineering. One of the key decision-making issues for reducing tunnel construction costs is to optimize the main driving parameters to increase the feed speed of the jumbo drill. The optimization of the driving parameters is supposed to meet the requirements of high reliability and efficiency due to the high risk and complex working conditions in tunnel engineering. The flaws of the existing optimization algorithms for driving parameter optimization lie in the low accuracy of the evaluation functions under complex working conditions and the low efficiency of the algorithms. To address the above problems, a driving parameter optimization method based on the XGBoost-DRWIACO framework with high accuracy and efficiency is proposed. A data-driven prediction model for feed speed based on XGBoost is established as the evaluation function, which has high accuracy under complex working conditions and ensures the high reliability of the optimized results. Meanwhile, an improved ant colony algorithm based on dimension reduction while iterating strategy (DRWIACO) is proposed. DRWIACO is supposed to improve efficiency by resolving inefficient iterations of the ant colony algorithm (ACO), which is manifested as falling into local optimum, converging slowly and converging with a slight fluctuation in a certain dimension. Experimental results show that the error by the proposed framework is less than 10%, and the efficiency is increased by over 30% compared with the comparison methods, which meets the requirements of high reliability and efficiency for tunnel construction. More importantly, the construction cost is reduced by 19% compared with the actual feed speed, which improves the economic benefits.

Spatio-Temporal Variation and Future Sustainability of Net Primary Productivity from 2001 to 2021 in Hetao Irrigation District, Inner Mongolia

The Hetao Irrigation District in Inner Mongolia, a vital grain-producing region in northern China, faces growing environmental challenges. Studying net primary productivity (NPP) is essential for understanding spatiotemporal vegetation shifts and guiding locally adapted restoration and management efforts. Utilizing MOD17A3/NPP data, this study applies the Theil–Sen median trend, Mann–Kendall significance, and the Hurst index to scrutinize the spatiotemporal distribution patterns of NPP from 2001 to 2021 and forecast future changes in the area. The findings reveal cyclic temporal trends, forming a “∧” shape with initial increases followed by decreases, notably during the July to August period each year. The multi-year average NPP exhibits a slight upward fluctuation trend, averaging 172.40 gCm−2a−1. Peaks occur approximately every three years, reaching the highest average in 2012 at 218.96 gCm−2a−1. Spatially, NPP distribution stays consistent over the years, influenced by various land cover types, especially cropland, shaping the spatial patterns. Monthly and yearly NPP trends over the 21 years indicate a significant decrease in May and June, with other months mostly showing a non-significant increase. The Hurst index for monthly and yearly NPP changes over 21 years shows relatively high weak anti-persistence. In summary, over the past 21 years, the NPP trend in the study area has not significantly improved and is expected to decline in the future. This study offers data support and a scientific foundation for refining the carbon cycle model, quantifying vegetation carbon sequestration capacity, addressing climate change policies, and striving for carbon peak and neutrality in the Hetao Irrigation District.

The Effects of Parameter Settings on Triggering Time and Climb Rate during Lean-Premixed Combustion Thermoacoustic Oscillations

This study theoretically explored the effects of parameter settings on thermoacoustic oscillations with a low-order model. Three factors were explored—combustor length, inlet gas temperature and thermal power. The research findings indicate that optimizing the parameter settings can yield better thermoacoustic oscillation suppression results. The sound pressure amplitude decreased from 3.2 × 105 Pa to 2.1 × 105 Pa as the combustor length increased from 1.2 m to 6.0 m. The triggering time increased from 0.32 s to 0.91 s when the combustion chamber length increased. The climb rate declined from 23.38 × 105 Pa/s to 3.75 × 105 Pa/s when the combustor length was elongated. The sound pressure amplitude decreased from 3.44 × 105 Pa to 2.4 × 105 Pa as the gas temperature rose from 0 to 100 °C. The triggering time and climb rate variation tendency were similar when the gas temperature increased—both declined as the gas temperature rose. The sound pressure amplitude experienced a slight fluctuation when the thermal power rose. However, the triggering time decreased from 0.26 s to 0.043 s when the thermal power improved. The climb rate increased from 18.72 × 105 Pa/s to 27.65 × 105 Pa/s when the thermal power rose. The oscillation frequency presented was completely different in three cases that had different wavelengths and oscillation intensities. The triggering time and climb rate fluctuated extensively in varying conditions, and the above two factors were interrelated and contradictory to each other when thermoacoustic oscillation was excited. This study explored parameters’ effects on triggering time and climb rate, thereby providing references for constructing a model-based control system for thermoacoustic oscillation feedback control.

Numerical Study on the Torsional and Lateral Vibrations of Double Universal Joint Driveline System

Utilizing a universal joint can lead to significant vibration within a driveline system. This study presents a model for analyzing the torsional and lateral vibrations of a driveline connected by a double universal joint. The governing equations of motion are derived, and the Runge-Kutta method computes steady-state responses across a spectrum of input rotational speeds. The focus is to examine the effect of system parameters, including static angular misalignment, load torque, and lateral stiffness. Relative amplification is used to analyze the effects of parameters on system vibration. Results indicated that the second-order component of input rotational speed induced by the universal joint was the factor that caused the vibrations. For the considered system, static angular misalignment significantly impacts both the torsional and lateral vibrations. Increasing the angular misalignment from 15° to 30° results in a threefold increase in lateral vibration amplification, while torsional vibration amplification is increased by nearly two times. The effect of load torque is almost linearly proportional to torsional vibration but is nonlinear to lateral vibration. Thus, lateral vibration is significantly impacted compared to torsional vibration for higher load torque. Changing the stiffness leads to a modification of the natural frequency. Increasing the lateral stiffness shifts the critical speed to a higher speed range, resulting in reduced lateral vibration amplitude. It is demonstrated that a slight fluctuation in angular misalignment due to lateral vibration will not affect the torsional vibration even if both vibrations are coupled. The findings may enhance understanding of how changing system parameters affects vibration.

Inner Surface Morphology and Roughness Evolution of Pilgering Thick-Walled Tubes.

A hot-working die steel thick-walled tube Pilger rolling test was carried out using an LG40 Pilger mill, and the morphology and roughness evolution of the inner surface were examined using a white-light interferometer. The experimental results showed that micro-wrinkles formed on the basis of the original inner surface morphology, the altitude difference (Sz) between the peaks and valleys of the inner surface profile increased from 3.18 to 3.686 μm, and Sa increased from 0.722 to 0.892 μm in the diameter reduction zone. As the tube continued to feed into the wall thickness reduction zone, the micro-wrinkles gradually flattened, Sz and Sa were decreased to 1.625 and 0.174 respectively, and Sa maintained a slight fluctuation of 0.174~0.2 μm in the final sizing zone. From the diameters of the roller groove and taper of the mandrel, the three-dimensional strain of the tube in the wall thickness reduction zone was calculated, and the strain state of the tube in the complete deformation zone could be analyzed by finite element simulations. We found that in the diameter reduction zone, the inner surface was not supported by the mandrel and was free, while micro-wrinkles formed under circumferential compressive strain. In the wall thickness reduction zone, the deformation of the inner surface was controlled by the mandrel, and the micro-wrinkles were gradually flattened by radial compressive strain. The ratio of radial to circumferential strain was the key to flattening the micro-wrinkles, and when the ratio increased, the inner surface roughness (Sa) was reduced to 0.174 μm. In the sizing zone, the radial and circumferential strains were small, and the inner surface roughness showed no obvious fluctuation.

A high-stability neutron generator for industrial online elemental analysis

The yield stability of the neutron generator directly affects the accuracy of elemental analysis. This paper presents an industrial fully automatic neutron generator with a 48 mm neutron tube based on PLC to improve the stability and reliability of the neutron generator in industrial applications. By integrating a Kalman Filter with the PID algorithm in a PLC, the neutron yield of the generator is remarkably stabilized, achieving 1 × 108n/s. The neutron generator has been employed for industrial online elemental analysis. The results demonstrate that only a slight fluctuation of ±0.82 % exists in the neutron yield, and the reproducibility of the generator holds at a significant level of 0.05. This improved neutron generator can be applied to the online bulk analysis of carbon in coal-fired power stations and absolute measurement of neutron source emission rate.

Interplay of sociodemographic factors and antenatal care attendance with free maternal care policy: a case study of Ghana

IntroductionThe Free Maternal Care Policy (FMCP) was introduced in Ghana around 2008 as part of the government’s efforts to improve maternal and child health outcomes in the country. The policy...

Sensorless control of dual three-phase permanent magnet synchronous motor based on speed feedback and frequency-variable tracking.

The dual three-phase Permanent Magnet Synchronous Motor (PMSM) control system is characterized by its high reliability, slight torque fluctuation and low harmonic content. It is very suitable for systems requiring high power output and high reliability, for instance, electric vehicles, aerospace and military equipment. In this paper, a full speed domain sensorless control technology for dual three-phase PMSM is proposed which solves the limitations of other sensorless controls, improves system accuracy and stability, and has high practicality in fields such as new energy vehicles. The mathematical model of this motor in a static coordinate system is established, and the sine and cosine signals along with the velocity and angle information are obtained by using the flux linkage observer. Moreover, the estimated angle error parameter is introduced into the flux linkage observer; as a result, the estimation accuracy is improved by the estimated speed feedback, and the current frequency is tracked by the stator current Frequency-Variable Tracker (FVT) to reduce the current error. Meanwhile, to make the observer's estimation more accurate and to improve its ability to resist disturbance, a rotor disturbance is added to act as a disturbance variable. Through the mechanical motion equation of the motor, a fourth-order Extended State Observer (ESO) is built to calculate the rotor position and speed. Finally, the technology accuracy is verified using simulation and experimental results. The findings prove that the sensorless detection technology, with speed feedback introduce in this paper, has good reliability and high precision for dual three-phase PMSM under dynamic and static conditions.

Response of surface energy fluxes and hydrothermal characteristics to night‐time precipitation changes in the southeastern Tibetan Plateau

AbstractThis study aimed to evaluate the applicability of the land‐surface model CLM 4.5 in the southeastern Tibetan Plateau by utilizing field observation data from Kabu and Pailong sites. Furthermore, the study investigated the impact of night‐time precipitation changes on radiation, surface energy fluxes and soil hydrothermal characteristics in this region. Results revealed that CLM 4.5 accurately simulated upward shortwave/longwave radiation, surface energy fluxes and soil temperature in this region. However, the simulation of soil moisture exhibited a slight fluctuation of the simulated value during precipitation, resulting in poorer performance during heavy precipitation and a failure to simulate the rapid change of latent heat flux and soil moisture. Sensitivity experiments demonstrated that night‐time precipitation significantly influenced upward shortwave/longwave radiation, energy budge and soil hydrothermal processes, with each element changing considerably with changes in precipitation. Surface energy fluxes and hydrothermal characteristics were found to be more sensitive to increased precipitation than decreased precipitation. Additionally, soil moisture was found to play a crucial role in the impact of precipitation changes on surface energy fluxes and hydrothermal characteristics. Furthermore, the study also found that changes in precipitation had a more pronounced effect on relatively dry areas and seasons than already extremely wet areas and seasons. Finally, the variation in soil moisture was found to be restricted by the original soil moisture. In conclusion, this study highlighted the significant influence of night‐time precipitation on surface hydrothermal characteristics and surface energy budget in the southeastern Tibetan Plateau.

Which physiological measurements can characterize core and surface body temperature? A case study in stable thermal environment

Core and surface body temperature are physiological indicators commonly used in human-environment researches, but which specific body temperatures can characterize them have not been thoroughly explored. A case study was conducted in three stable thermal environments, where five kinds of body temperatures (intra-abdominal temperature, oral temperature, auditory canal temperature, breath temperature, and skin temperature) and two types of thermal perception (thermal sensation and thermal comfort) votes were regularly collected. Upon comparing measurements with theoretical classification principles, we found that both oral temperature and intra-abdominal temperature exhibited characteristics consistent with core temperature, while both mean skin temperature and breath temperature exhibited characteristics consistent with surface temperature. In addition, the comparison analysis between newly proposed indicators and gold standards further confirmed application prospects, as the average temperature difference between intra-abdominal and oral remained consistently below 0.1 °C, and the average temperature difference between skin and breath exhibited a slight fluctuation around fixed values. Generally, the findings of this study provide insights into the selection and application of body temperature indicators, while reminding researchers should not blindly follow the previous standards.

Polypyrrole zinc-doped film deposited on a plasma-treated surface improves the tribocorrosion behavior of titanium dental implant material

Polypyrrole (PPy) films have shown attractive electrochemical properties and promising implant applications when electrodeposited on plasma electrolytic oxidation (PEO) surfaces. Although the PEO + PPy surface demonstrates excellent mechanical and electrochemical performance, there are no reports on the effects of combined corrosion and mechanical interactions, which simulates the oral environment. In addition, since implant failures may be related to deficiencies in the osseointegration process, the electrodeposition of zinc (Zn) on the coating can promote an osteogenic substrate. Therefore, we aimed to investigate the tribocorrosion behavior of PEO-treated surfaces coated with PPy films with and without Zn and whether such PPy films affect the cellular response of MG-63 human osteoblast-like cells. Titanium discs with machined and PEO-modified surfaces were considered as controls. The experimental groups used PEO surfaces followed by electrodeposition of PPy (PEO + PPy) and PPy and Zn (PEO + PPy/Zn). The surfaces' physical-chemical properties were assessed. The tribocorrosion tests were run under free potential and potentiostatic (anodic and cathodic potentials) conditions using a pin-on-disk tribosystem simulating the oral environment (load = 1 N, stroke = 2 mm, number of cycles = 2000). Electrochemical impedance spectroscopy was performed before and after tribocorrosion to analyze the changes in corrosion kinetics. Worn areas were observed using white-light-interferometry and scanning electron microscopy. For in vitro cell experiments, the viability, number of live/dead cells, adhesion ability, and mineralization property of cells were evaluated. Our outcomes revealed that PPy films improved tribocorrosion performance by exhibiting more positive OCP values and slight fluctuation and variation of the current value during the sliding phases. In general, due to the films' morphology and “cushion effect”, PPy films enhanced the surface resistance against corrosion and wear, indicating a low total weight loss (Kwc) and wear-corrosion degradation mechanism. The PEO + PPy/Zn surface was cytocompatible, enhancing the cell adhesion and proliferation on the surface. Overall, PPy films represent a promising coating to improve the stability and lifetime of biomedical implants.

Brushed Nano‐Stirbars for Measuring Viscosity in Microscopic Systems

AbstractConventional methods for measuring viscosity rely on macroscopic device components, which are difficult to miniaturize. The magnetic nano‐stirbars are small enough to enter tiny spaces and can spin without precise installation, making them an ideal candidate for exploring new methods. It is shown that a dense layer of Au nanowires can be grown on the silica surface of the nano‐stirbars, as a means to modulate the viscous resistance during their spinning and to make them visible under an optical microscope. The uniform growth of Au nanowires and the slight fluctuation of the spinning rates are investigated. It is shown that the nano‐stirbars with the hairy layer of Au nanowires can be used to measure the viscosity in microscopic liquid systems, such as microfluidic chambers and capillary tubes, involving cell media and blood samples. It is believed that the success with the proof‐of‐concept tests will open a window for further miniaturization of the nano‐stirbars for measuring in ultrasmall systems.