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The leakage of shield tunnels built in confined aquifers of silt or fine sand may result in the erosion of soil. Due to the loss of ground support, significant distortions of the tunnel structure may arise. As an initial insight into the mechanisms driving disaster chains, the erosion morphology of silt or fine sand under converging flow should be made clear first. In this study, a series of laboratory tests were performed to investigate the erosion morphology of fine sand under converging flow and its spatiotemporal evolution. Notably, for consistency with practical engineering, the initial effective stress of the soil was also considered. The initial results indicated that the erosion process may involve the soil arching effect due to the presence of soil effective stress. On this basis, tests with two leakage points were conducted. It was found that successively opening the two leakage points may lead to a larger erosion area of superposition when compared with the case of simultaneously opening two leakage points. [ABSTRACT FROM AUTHOR]

In order to improve machining efficiency and quality of aero-engine blisks, a novel multi-spindle 5-axis machine tool is developed under the inspiration of the blisk structure. The proposed machine contains 8 spindles, which are arranged radially along the blisk and simultaneously participate in machining. The actuator of the machine contains three rotation axes and two translation axes, which can realize 5-axis CNC machining. Based on the unified kinematics model, the mechanism is analyzed in terms of forward and inverse kinematics, singularity, and flexible workspace. Meanwhile, the structural parameters of the machine are optimized according to the flexibility index to improve the kinematic performance of the mechanism. Theoretical and experimental results show that the machine tool has a more compact structure, fewer moving axes, and better kinematics performance, compared with the traditional multi-spindle modular machine tool. Therefore, the machine has significant advantages in processing efficiency and has great application potential in large batch machining of the blisk. [ABSTRACT FROM AUTHOR]

The coronavirus disease 2019 (COVID‐19) pandemic has greatly stressed the global community, exposing vulnerabilities in the supply chains for disinfection materials, personal protective equipment, and medical resources worldwide. Disinfection methods based on cold atmospheric plasma (CAP) technologies offer an intriguing solution to many of these challenges because they are easily deployable and do not require resource‐constrained consumables or reagents needed for conventional decontamination practices. CAP technologies have shown great promise for a wide range of medical applications from wound healing and cancer treatment to sterilization methods to mitigate airborne and fomite transfer of viruses. This review engages the broader community of scientists and engineers that wish to help the medical community with the ongoing COVID‐19 pandemic by establishing methods to utilize broadly applicable CAP technologies. [ABSTRACT FROM AUTHOR]

The climate change on the Tibetan Plateau (TP) exhibits a north-south dipole trend during the Holocene. However, it is unclear whether regional differences exist in the variations and driving mechanisms of dust storm activities across the entire TP, and whether these mechanisms align with those found in monsoonal northern China. Here, we present a high-resolution Holocene record of dust storms from an undisturbed lake in the research gap area of the TP, and compile previously published records from other TP regions. Our findings indicate that the dust storm activity increased from the early Holocene to the late Holocene, peaking after 5 cal ka BP. Importantly, our comparison with other dust storm records reveals a unified intensification of dust storm activity across the entire TP during the late Holocene, a pattern distinctly different from the north-south dipole trend of precipitation variation. Moreover, this unified pattern of dust storm intensification across the TP cannot be explained by the decreasing intensity of the East Asian winter monsoon (EAWM) during the Holocene. The observations suggested a limited role for precipitation and EAWM in modulating TP dust storms on the millennial timescale during this period. By contrast, the increases in dust storms on the TP after 5 cal ka BP correlates well to the southward shift of the westerly jet driven by the North Atlantic Oscillation (NAO). As the NAO transitioned to a negative phase during the late Holocene, a meandering westerly jet shifted southward to the interior of the TP, intensifying wind intensity and leading to dust storm outbreaks. • Holocene dust storm record in the crucial research gap area of the Tibetan Plateau (82 characters). • A spatial consistency in Holocene dust storm changes over the entire Tibetan Plateau (84 characters). • Low frequency of dust storm activity during the early and middle Holocene (73 characters). • Southward shift of the westerly drove dust storm outbreaks during the late Holocene (83 characters). [ABSTRACT FROM AUTHOR]

Contact calculation is of great importance in predicting the material removal (MR) of flexible grinding process (FGP). The contact is mostly considered approximately constant in the existing MR models, while the situations that contact varies a lot after FGP are ignored. Therefore, a novel model is proposed in this paper to take those situations into consideration. Firstly, the nonconstant-contact situation is introduced. Then, an equivalent method is developed to convert the nonconstant-contact grinding process into the accumulation of several quasi-constant-contact grinding processes. Based on the equivalent method, a MR model is established, and the procedure to obtain the model parameters by the finite element analysis (FEA) is introduced. In the end, the equivalent method and the MR model are tested by a series experiments of different process parameters. Results show that the proposed MR model can predict the material removal effectively for the nonconstant-contact situations. [ABSTRACT FROM AUTHOR]

[Display omitted] As the fourth state of matter, plasma's unique properties and interactions with other states of matter offer many promising opportunities for investigation and discovery. In particular, cold atmospheric plasma (CAP), operating at atmospheric pressure and room temperature, has remarkable potential for biomedical applications through various delivery methods. These biomedical applications include sterilization, wound healing, blood coagulation, oral/dental diseases treatment, cancer therapy, and immunotherapy. Effective delivery of plasma constituents is critical to its efficacy for these applications. Therefore, this review presents the key research activities related to CAP delivery (including direct CAP delivery, delivery of plasma-activated media, biomedical device-assisted plasma delivery, and CAP delivery with other therapeutics) and needs for future research. This review will be of great interest for understanding the current state-of-the-art of biomedical applications of plasma medicine while also giving researchers from a broad range of communities insight into research efforts that would benefit from their contributions. Such communities include biomedicine, physics, biochemistry, material science, nanotechnology, and medical device manufacturing. [ABSTRACT FROM AUTHOR]

The sculptured surface has been widely used in aerospace and machinery manufacturing industries. CNC machining of sculptured surfaces is an important research area, and computation efficiency improvements are considered critical topics in this field. This paper presents a highly efficient method to generate smooth tool paths by establishing a mathematical model to describe the relationship between the relative curvature of sculptured surface and the machining strip width in five-axis machining. The method is improved from the middle-point error control method (MPECM) and the feasible tool position surface method (FTPSM), by changing the objective from the complete optimization for each drive point to the drive points' interpolation. The drive point with the narrowest machining strip width and some sample points is selected to interpolate the remaining points. Both theoretical analysis and test examples show the correctness of the proposed method. Under the same condition, compared with the MPECM and the FTPSM, the computing time of the new method decreases to 10% at least. Besides, the fluctuation of the tool path is reduced. The machining examples verified the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

The lower Yangtze is one of the regions of origin of rice agriculture but it is unclear if environmental change drove the transition from hunting-gathering to agriculture. Long-term and continuous lacustrine records of anthropogenic fire are a more effective means of addressing this problem than the fragmentary terrestrial records available for the lower Yangtze region. We constructed a Holocene fire history revealed by records of black carbon content (BCC) and grain size of the sediments of Lake Nanyi in the lower Yangtze. Our results show the following: 1) Peaks in fire activity occurred during ∼8400–6500 (fire peak P1) and ∼ 1100–0 cal BP (fire peak P2), while weaker fire activity occurred during ∼6500–1100 cal BP (S2). 2) This temporal pattern of fire activity, with a double peak (P1-S2-P2), was asynchronous from east to west across the lower Yangtze. The warm and humid climate would not have caused intense fires and the reduction of forest during ∼8400–6500 and ∼ 1100–0 cal BP. Therefore, we suggest that anthropogenic ignitions, corresponding to pronounced population fluctuations after 8400 cal BP, dominated the regional fire activity. Combined with archaeological evidence, the inverse relationship between the agricultural and population levels and fire intensity during the mid-Holocene suggests that fire intensity at this time was the result of the diversity of landscape types associated with prehistoric subsistence patterns, rather than the magnitude of anthropogenic activity. Combined with sea level, rainfall and archaeological evidence, we propose a mechanism whereby asynchronous water-level rise during ∼8400–6500 cal BP forced the migration of humans to the foothills where they often used fire to modify the landscape as part of a broad-spectrum subsistence pattern. Whereas, water-level fall after 6500 cal BP expanded the area of open ground for human settlement, and in this less diverse landscape, less use was made of fire in agricultural subsistence. Overall, our study reveals how regional water-level, driven by sea-level rise and extreme rainfall, delayed the transition from hunting-gathering to agriculture in the lower Yangtze region. • The Holocene fire history representing the lower Yangtze area is reconstructed. • Paleofire in the lower Yangtze area peaked during ∼8400-6500 cal BP and 1100-0 cal BP. • Increased burning of forests by human-induced fire peaks in the lower Yangtze area. • Prehistoric subsistence regimes dominated the burning strategy in the lower Yangtze area. • Rising water level delayed the emergence of prehistoric agriculture in the lower Yangtze area. [ABSTRACT FROM AUTHOR]

The Tibetan Empire, the only united regime in Tibetan history, existed between 618 and 877 CE, when Tibet was a unified world power, contesting control of Central Asia with the Tang Empire and the Abbasid Caliphate. Before its collapse in the 9th century, this was the world's highest elevation empire, ruling a vast territory that extended well beyond the Tibetan Plateau. However, factors leading to the rapid decline of this powerful highland empire remain elusive. Here we use a highly resolved lake sediment record from the western Tibetan Plateau to demonstrate that pronounced fluctuations in the climate regime between the 7th and 9th centuries played a key role in the fragmentation of the Tibetan Empire. Specifically, we demonstrate that a nearly complete shift from planktonic to benthic diatom life strategy signified markedly drier conditions and lower lake-levels. The height of the empire's power (ca. 600–800 CE) coincided with two centuries of uncharacteristically warm and humid conditions, whereas the empire's collapse (ca. 800–877 CE) co-occurred with an abrupt onset of severe drought conditions that were clearly registered in the paleolimnological records. Severe drought conditions combined with decreased social resilience might have led to rapid declines in crop production, which fostered a surge in domestic conflicts and expediated the final collapse of the Tibetan Empire. Although religious and political factors are commonly cited to explain the fall of this formidable great power, our paleoenvironmental analyses underscore that harsh environmental factors might have hastened the cultural decline of this highland region. • Paleolimnological data from a rare freshwater lake in the western Tibetan Plateau. • Abrupt collapse of the Tibetan Empire around 9th century linked to severe drought. • Rise and fall of empire linked to marked climate shifts between 7th and 9th centuries. • These changes were detrimental to the political unity of the Tibetan Plateau. • Diatoms closely tracked changes in lake level. [ABSTRACT FROM AUTHOR]

• Presents an indirect evaluation of the equivalent notch root radius of the surface profile——the arch-height & chord-length formula. • No single direct index of surface profile can determine the fatigue strength, but the indirect indexes, the notch bottom radius and the stress concentration factor can be used. • The surface notch roots radius ρ is the key to the stress concentration coefficient. Using the arch-height & chord-length formula, the linear fitting goodness of the stress concentration coefficient and the fatigue strength reaches 0.9. Considering the current controversy about the key indicators of surface roughness, this paper presents an indirect evaluation of the equivalent notch root radius of the surface profile. Using this method, the influence of surface roughness on fatigue strength on GH4169 is studied. Various sets of specimens with different fabrication conditions are machined to get a wide range of surface roughness. Vacuum annealing treatment is conducted on some of the specimens to eliminate the effect of residual stresses. Different classical formulae for stress concentration factor based on the notch root radius of the surface profile are used and the fatigue life reduction factor for various surface roughness values is presented. The results show that no single direct index of surface profile can determine the fatigue strength, but the indirect indexes, the notch bottom radius and the stress concentration factor can be used. The surface notch roots radius ρ is the key to the stress concentration coefficient. Using the arch-height & chord - length formula proposed in this paper to evaluate ρ , the linear fitting goodness of the stress concentration coefficient and the fatigue strength reaches 0.9. [ABSTRACT FROM AUTHOR]

Blade is the core component of aero-engine, and its manufacturing capability improvement has always been the focus of aviation manufacturing industry. With the high-efficiency machining of multi-spindle machine tool, this paper proposes a synchronous polishing method based on the cluster grouping of actual blade profile. Firstly, the multi-spindle machining system, flexible polishing with determined path, and synchronous polishing process cycle are analyzed in detail. Secondly, the allowable difference within group is determined by the relationship of polishing compression and surface roughness/removal. Then, the distribution of grouping mark points is determined by the profile differences of sampled blades. Thirdly, the consistency of each two blade profiles is expressed as the vector difference of measurement data, and the grouping result can be established with the Ray-Turi index. Finally, a typical blade is used to demonstrate the effectiveness and efficiency. After multi-spindle synchronous polishing, the average synchronous polishing cycle time is 3.14 times less than single-spindle machine tool, the profile error and its difference are less than 0.0685 mm and 0.048 mm, the surface roughness can satisfy Ra ≤ 0.4 μ m , which can meet the design requirement of aero-engine blade. [ABSTRACT FROM AUTHOR]

A six-axis machining configuration is proposed to improve the surface quality and finishing efficiency of an aeroengine blisk. It flexibly enlarges the accessible interference-free space of the tool for finishing the full-shape surface, including the blade body, root, and hub surfaces. An error model for tool contact posture with respect to the kinematic axis errors is established, revealing the relationship between the kinematic deviation of the axes and resultant profile error. An improved Sobol method is applied for error sensitivity analysis to identify crucial error terms based on the quasi-Monte Carlo algorithm. In particular, an efficient error sensitivity index is proposed by combining a unified objective function to identify crucial error terms, followed by the simulations and cutting experiments for validation. As a result, the blade profile error was successfully suppressed by approximately 40 % in most. This work provides a fundamental framework for elevating the multi-axis machining accuracy of aeroengine blisk. • A six-axis machine tool has been proposed to achieve the full-shape-surface grinding on the blisk. • A constrained error sensitivity index model was proposed to compensate for key error terms. • Sensitivity analysis was conducted using an improved Sobol method incorporated quasi-Monte-Carlo algorithm. • The effectiveness of error sensitivity analysis and corresponding tool-path-based compensation were verified. [ABSTRACT FROM AUTHOR]

This article discusses the use of cold atmospheric plasma (CAP) as a potential treatment for chordomas, a type of skull base tumor that is difficult to treat. CAP is a room temperature gas that has been shown to have anti-tumor effects in various types of cancer. The study found that CAP exposure decreased the survival of chordoma cells in vitro. Further research is needed to understand the mechanism of cell death and how to increase the sensitivity of chordoma cells to CAP. [Extracted from the article]

The aero-engine blade is typically a thin-walled part with poor rigidity and a complex structure. This causes aero-engine blades to be susceptible to flutter and deformation during the machining processing, leading to the dimensional and positional accuracy outside the stipulated tolerance values. With the aim of improving the machining precision of the blades, the conventional blade processing methods were analysed in this study. Based on the analysis, a novel deformation control method named reverse segment machining method was proposed. Additionally, a stress-free auxiliary fixture was designed to improve the stiffness of thin-walled parts. Finally, an experiment was conducted to study the effectiveness of the developed reverse segment method and the stress-free auxiliary fixture in comparison to the forward machining methods. The results show that they can significantly improve machining precision. [ABSTRACT FROM AUTHOR]

This article presents a resistor-array-tuning-based hybrid adaptive digital delay compensated rectifier for wireless power transfer systems. A no-crossing problem and nonlinearity problem for conventional delay-compensations are analyzed. In order to enhance the robustness of digital control, the on-delay and off-delay are compensated with different compensation schemes. The on-delay is compensated with a comparator-offset-adjusted technique, while the off-delay is compensated with a pulsewidth modulation (PWM)-based technique to guarantee falling zero-voltage crossing and adjust off-delay time linearly. Compared with the previous works, the delay time is adjusted by tuning the voltage drop across resistor arrays instead of changing the injected offset current of push–pull comparator so as to improve the power conversion efficiency (PCE) and loop stability. Implemented in a 0.18- $\mu$ m BCD process with a total area of 0.446 mm $^{2}$ , the rectifier delivered a maximum output power of 54.5 mW. With a 13.56 MHz ac input voltage in the range of 2.5 and 3.3 V, the measurement results show the peak VCR of 96.1 $\%$ and peak PCE of 93.1 $\%$ for the load resistance of 2 k $\Omega$ and 500 $\Omega$ , respectively. [ABSTRACT FROM AUTHOR]

Due to their potential benefits, cold atmospheric plasmas (CAPs), as biotechnological tools, have been used for various purposes, especially in medical and agricultural applications. The main effect of CAP is associated with reactive oxygen and nitrogen species (RONS). In order to deliver these RONS to the target, direct or indirect treatment approaches have been employed. The indirect method is put into practice via plasma-activated water (PAW). Despite many studies being available in the field, the permeation mechanisms of RONS into water at the molecular level still remain elusive. Here, we performed molecular dynamics simulations to study the permeation of RONS from vacuum into the water interface and bulk. The calculated free energy profiles unravel the most favourable accumulation positions of RONS. Our results, therefore, provide fundamental insights into PAW and RONS chemistry to increase the efficiency of PAW in biological applications. [ABSTRACT FROM AUTHOR]

In this work, honeycomb-like SiO x coating was successfully prepared on steel surface by atmospheric pressure low temperature plasma jet. The surface morphology, corrosion resistance and stability of the coating were systematically analyzed. In addition, the growth mechanism of the coating was discussed. The analysis revealed that the coatings were primarily composed of Si-O-Si and Si-OH groups, with a minor presence of Si-CH 3 moieties. The coating obtained after two deposition cycles exhibits the highest level of uniformity and density, with minimal porosity and superior corrosion resistance. The increase in deposition cycles led to particle aggregation, augmented particle dimensions and porosity, which adversely affected the coating's performance. The dense SiO x coating resulted in a significant reduction in the corrosion current density of the alloy steel, and showed no significant corrosion defects when exposed to the crude oil simulant in 25 °C. The coating simultaneously enhanced the hydrophilicity and oil transfer of the steel surface. Finally, the coating exhibited self-cleaning properties, stability and high potential for safeguarding steel pipes against low-viscosity crude oil contamination. This study provides a general surface modification method for the preparation of corrosion-resistant coatings on metal surfaces under mild conditions. [ABSTRACT FROM AUTHOR]

In the present paper, the strength and interfacial properties of square-wave joints under tension are analyzed. By using the bilinear cohesive zone model, three main factors in practice, including geometric parameters, preexisting defects and mismatches, are considered. It is found that the strength and fracture toughness of the joints can be improved by proper adjustment of geometric parameters of the joint. What is more, the length of defect has a great influence on the mechanical properties of the adhesive joints, different from the defect's location. Compacting adherends tightly during glue consolidation, making the bonding part as symmetrical as possible and introducing some protuberances on square-wave plug are found to be helpful to improve the joints' mechanical behavior. The findings should be useful for the design of square-wave joints and the assessment of mechanical properties of adhesive joints in practical and potential applications. [ABSTRACT FROM AUTHOR]

A novel method for the in situ visualization and profilometry of a plasma-facing surface is demonstrated using a long-distance microscope. The technique provides valuable in situ monitoring of the microscopic temporal and morphological evolution of a material surface subject to plasma–surface interactions, such as ion-induced sputter erosion. Focus variation of image stacks enables height surface profilometry, which allows a depth of field beyond the limits associated with high magnification. As a demonstration of this capability, the erosion of a volumetrically featured aluminum foam is quantified during ion-bombardment in a low-temperature argon plasma where the electron temperature is ∼7 eV and the plasma is biased relative to the target surface such that ions impinge at ∼300 eV. Three-dimensional height maps are reconstructed from the images captured with a long-distance microscope with an x–y resolution of 3 × 3 μm2 and a focus-variation resolution based on the motor step-size of 20 μm. The time-resolved height maps show a total surface recession of 730 μm and significant ligament thinning over the course of 330 min of plasma exposure. This technique can be used for developing plasma-facing components for a wide range of plasma devices for applications such as propulsion, manufacturing, hypersonics, and fusion. [ABSTRACT FROM AUTHOR]

Despite the promise of immune checkpoint blockade (ICB) for cancer treatment, challenges associated with this therapy still exist, including low response rates and severe side effects in patients. Here, we report a hydrogel-mediated combination therapy for enhanced ICB therapy. Specifically, cold atmospheric plasma (CAP), an ionized gas consisting of therapeutically effective reactive oxygen species (ROS) and reactive nitrogen species (RNS), can effectively induce cancer immunogenic cell death, releasing tumor-associated antigens in situ and initiating anti-tumor immune responses, which, therefore, can synergistically augment the efficacy of immune checkpoint inhibitors. To minimize the systemic toxicity of immune checkpoint inhibitors and improve the tissue penetration of CAP, an injectable Pluronic hydrogel was employed as a delivery method. Our results show that major long-lived ROS and RNS in CAP can be effectively persevered in Pluronic hydrogel and remain efficacious in inducing cancer immunogenic cell death after intratumoral injection. Our findings suggest that local hydrogel-mediated combination of CAP and ICB treatment can evoke both strong innate and adaptive, local and systemic anti-tumor immune responses, thereby inhibiting both tumor growth and potential metastatic spread. [ABSTRACT FROM AUTHOR]

Selective and sensitive determination of L -cysteine (L -Cys) plays an important role in clinical diagnoses and regulation of L -Cys level. However, glutathione (GSH) interferes greatly with the L -Cys detection due to their similar electrochemically active functional sulfhydryl groups and the high abundance of GSH in biological samples. Herein, Ni 2 P nanocrystallines anchored on black phosphorus nanosheets (Ni 2 P @ BPNSs) electrocatalysts were prepared by an in-situ solvothermal method using BPNSs as phosphorus sources and substrate. The electrochemical behaviors of Ni 2 P @ BPNSs with different Ni 2 P contents were studied for L -Cys determination. The experimental and DFT calculation results reveal the extraordinary electrocatalytic and selective sensing mechanism of Ni 2 P @ BPNSs toward L -Cys is attributed to the high selective adsorption and electrocatalytic activity of Ni active sites, and BPNSs matrix. The electrochemical sensor displays low detection limit (2 nM), more negative oxidation potential (+0.30 V), extremely broad linear range (0.02 −1000 μM), excellent sensitivity (396.00 μA mM−1 cm−2), and extraordinary selectivity. The sensor has been practically applied in detection of L -Cys concentrations in serum and urine samples. This work opens the avenues for the engineering design of metal atoms decorated BP materials in biosensors with enhanced sensing performance by adjusting the properties of materials, allowing for more selective and sensitive analyte detection. [Display omitted] • 2D Ni 2 P nanocrystallines anchored BP nanosheet is fabricated through solvothermal method. • The Ni 2 P @ BPNSs hybrids exhibit extraordinary selective electrocatalytic activity to cysteine. • The Ni 2 P @ BPNSs show low overpotential, wide linear range and low LOD for cysteine detection. • The sensor is successfully applied to detect cysteine in various biological samples. • The electrocatalytic and selective sensing mechanism were clarified. [ABSTRACT FROM AUTHOR]

The improvement of the ignition and combustion performance of aerospace engines under extreme conditions such as high altitude, low temperature, low pressure, and high speed is a research topic of broad and current interest. Plasma technology has attracted increasing attention due to its significant potential in improving ignition and combustion performance. Scientists and engineers have conducted numerous investigations and experiments on the use of plasma technology in aerospace engines, especially in aviation gas turbine engines, driving the research and applications of plasma-assisted ignition (PAI) and plasma-assisted combustion (PAC). The aim of this comprehensive review paper is to summarize and discuss the developments and applications of PAI and PAC in the fields of aerospace engines during the last ten years, including ignition, lean blow-out, combustion efficiency, emission, outlet temperature distribution quality, combustion stability, and fuel distribution. This review paper mainly focuses on experimental research progress. We also introduce new applications of PAI and PAC in novel aerospace engines and discuss the prospects for its practical implementation. [ABSTRACT FROM AUTHOR]