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Hydraulic fracturing is the primary method used for oilfield stimulation, and the migration and settlement pattern of proppant plays a crucial role in the formation of high conductivity propping fractures in the reservoir. This study summarizes two growth modes of sand dune: the ‘overall longitudinal growth’ mode and the ‘push growth along fracture length direction’ mode. To investigate these modes, a two-phase velocity test is conducted using PIV, and the exposure difference is utilized to separate the tracer and track the single-phase velocity. By analyzing the slickwater flow field and proppant velocity field, the micro-motion mechanism behind the two dune growth modes is quantitatively examined. The results indicate that mode 1 growth of the sand dune occurs when a pump with a large mesh number, high polymer viscosity, and large displacement is used. On the other hand, mode 2 growth is observed when a pump with a small mesh number, low polymer viscosity, and small displacement is employed. It is important to note that there is no clear boundary for the migration and sedimentation mode of proppant, as they can transition into each other under certain conditions. These modes only exist during specific stages of sand dune growth. In the case of the ‘backflow’ pattern, the settlement of proppant is primarily influenced by the vortex structure of slickwater. Conversely, in the ‘direct’ pattern, the proppant is propelled forward by the drag of the fluid and settles due to its own gravity. Once the proppant placement reaches equilibrium, the direction of proppant velocity follows a normal distribution within 0°. This approach establishes a connection between the overall placement of the sand dune and the microscopic movement of the proppant and slickwater. Optimizing construction parameters during fracturing construction can enhance the effectiveness of distal proppant placement in fractures.

Abstract Human enteroviruses are highly prevalent world-wide. Up to more than 100 subtypes of enteroviruses can cause several diseases, including encephalitis, meningitis, myocarditis, hand-foot-mouth disease, conjunctivitis, respiratory diseases, and gastrointestinal diseases, thus posing a great threat to human health. This study aimed to investigate the epidemiological characteristics of enterovirus in children in Hangzhou, China before and after the COVID-19 outbreak. Systematic monitoring of enterovirus infections was performed by collecting samples from the children admitted to the inpatient wards and outpatient departments in the Children’s Hospital, Zhejiang University School of Medicine, between January 2019 and May 2023. A commercial real-time RT PCR kit was utilized to detect enteroviruses. Among the 34,152 samples collected, 1162 samples, accounting for 3.4% of the samples, were tested positive for enteroviruses. The annual positive rates of the enteroviruses were 5.46%, 1.15%, 4.43%, 1.62%, and 1.96% in 2019, 2020, 2021, 2022, and May 2023, respectively. The positivity rate of the enteroviruses was highest among children aged 3–5 years and 5–7 years. Moreover, the monthly positivity rate of enterovirus infection ranged from 0.32% to 10.38%, with a peak in June and July. Serotypes, especially EV71 and CA16, causing severe symptoms such as HFMD, were decreasing, while the proportion of unidentified serotypes was on the rise. The incidence of enteroviruses in Hangzhou was higher in children aged 1–3 years and 7–18 years.

Abstract The life‐threatening colorectal cancer exhibits multilevel immunosuppressive characteristics, including low immunogenicity, abnormal cellular metabolism, and acidic immunosuppressive microenvironment. In this work, multi‐synergistic chemotherapeutic drug assemblies are fabricated to activate colorectal cancer immunotherapy by modulating the multilevel immunosuppressive characteristics. Without any drug excipients, the glycolysis inhibitor of lonidamine (LON), indoleamine 2,3‐dioxygenase 1 (IDO‐1) inhibitor of NLG919 (NLG), and the photosensitizer of chlorine e6 could self‐assemble into drug assemblies (LNC) with uniform nano‐size distribution and increased drug stability. Moreover, LNC could also promote cellular uptake and enhance drug penetration to enable efficient drug co‐delivery. Especially, the photodynamic therapy (PDT) of LNC could disrupt tumor cells to release tumor‐associated antigens, thus efficiently suppressing primary tumor growth and improving tumor immunogenicity. Meanwhile, LNC could also reduce the activity of IDO‐1 and attenuate the glycolysis metabolism, thereby reversing the multilevel immunosuppressive characteristics to promote T cell activation. Benefiting from the multi‐synergistic effects, LNC efficiently eradicates the primary tumor growth and also activates systemic antitumor immunity for metastatic tumor inhibition. Such a simple formulation but a multi‐synergistic strategy may accelerate the development of translational nanomedicine for colorectal cancer immunotherapy by using small molecular drug combinations.

Abstract The kagome lattice is an exciting solid state physics platform for the emergence of nontrivial quantum states driven by electronic correlations: topological effects, unconventional superconductivity, charge and spin density waves, and unusual magnetic states such as quantum spin liquids. While kagome lattices have been realized in complex multi-atomic bulk compounds, here we demonstrate from first-principles a process that we dub kagomerization, in which we fabricate a two-dimensional kagome lattice in monolayers of transition metals utilizing an hexagonal boron nitride (h-BN) overlayer. Surprisingly, h-BN induces a large rearrangement of the transition metal atoms supported on a fcc(111) heavy-metal surface. This reconstruction is found to be rather generic for this type of heterostructures and has a profound impact on the underlying magnetic properties, ultimately stabilizing various topological magnetic solitons such as skyrmions and bimerons. Our findings call for a reconsideration of h-BN as merely a passive capping layer, showing its potential for not only reconstructing the atomic structure of the underlying material, e.g. through the kagomerization of magnetic films, but also enabling electronic and magnetic phases that are highly sought for the next generation of device technologies.

Abstract To enhance the security of image data transmission, and address the weaknesses of existing image encryption schemes based on chaotic systems, particularly concerning resistance to differential attacks and the unstable performance of chaotic systems, this article introduces an improved four-dimensional chaotic system and integrates evolutionary operators to propose an image encryption scheme. Firstly, a method for generating pseudo-random sequences associated with the plaintext is designed. The change rate of the ciphertext pixel value exceeds 0.9967 after a slight modification of the plaintext pixel value, significantly improving the plaintext sensitivity and the scheme's ability to resist selected plaintext attacks. Secondly, an individual rearrangement operation is introduced to achieve bit-level scrambling, and pixel-level scrambling is achieved by selection strategy. Subsequently, crossover and mutation operations are incorporated into image encryption. To reflect the randomness of the pairing, we adopt the pseudo-random sequence generated by the chaotic system to control the crossover and mutation operators, and a diffusion operation is performed on selected pixel pairs. Finally, ciphertext feedback is applied. Experimental results and performance analysis demonstrate that the proposed scheme not only enhances the security of encrypted images but also effectively resists noise and cropping attacks. This method effectively meets the high-security requirements of images in network transmission and provides new ideas for further research in the field of image encryption.

Since the discovery of innovative two-dimensional (2D) materials, significant efforts have been dedicated to exploring their intriguing properties and emerging applications. Among all candidates, transition metal dichalcogenides (TMDs) have proven to be exceptional for gas sensing, while defects engineering has been introduced to modify the pristine TMDs for better gas sensing performances. In this review, we systematically summarize types of defects, advanced characterization techniques, and state-of-the-art controllable synthetic methods. Various types of defects in TMDs can induce diverse changes in chemical and electron structures, which are closely correlated with gas sensing ability. Therefore, connections between defects and gas sensing mechanisms and performances have been addressed based on both defect categories and electron affinity of gases. This review will be a guide for researchers in defective materials and open up the field of precisely synthesis chemistry and deepen the understanding of the underlying effects of defects in other 2D materials.

The Omicron variant of SARS-CoV-2 has become dominant in most countries and has raised significant global health concerns. As a global commerce center, New York, New York, USA, constantly faces the risk for multiple variant introductions of SARS-CoV-2. To elucidate the introduction and transmission of the Omicron variant in the city of New York, we created a comprehensive genomic and epidemiologic analysis of 392 Omicron virus specimens collected during November 25–December 11, 2021. We found evidence of 4 independent introductions of Omicron subclades, including the Omicron subclade BA.1.1 with defining substitution of R346K in the spike protein. The continuous genetic divergence within each Omicron subclade revealed their local community transmission and co-circulation in New York, including both household and workplace transmissions supported by epidemiologic evidence. Our study highlights the urgent need for enhanced genomic surveillance and effective response planning for better prevention and management of emerging SARS-CoV-2 variants.

While membrane electrode assembly water electrolyzers are a promising renewable energy technology, further optimizations are needed before wide-spread implementation can occur. Here, authors examine a device with a porous membrane that enables oriented catalyst intergrowth to improve performances.

The recently emerged Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has quickly spread around the world. Although many consensus mutations of the Omicron variant have been recognized, little is known about its genetic variation during its transmission in the population. Here, we comprehensively analyzed the genetic differentiation and diversity of the Omicron variant during its early outbreak. We found that Omicron achieved more structural variations, especially deletions, on the SARS-CoV-2 genome than the other four variants of concern (Alpha, Beta, Gamma, and Delta) in the same timescale. In addition, the Omicron variant acquired, except for 50 consensus mutations, seven great new non-synonymous nucleotide substitutions during its spread. Three of them are on the S protein, including S_A701V, S_L1081V, and S_R346K, which belong to the receptor-binding domain (RBD). The Omicron BA.1 branch could be divided into five divergent groups spreading across different countries and regions based on these seven novel mutations. Furthermore, we found that the Omicron variant possesses more mutations related to a faster transmission rate than the other SARS-CoV-2 variants by assessing the relationship between the genetic diversity and transmission rate. The findings indicated that more attention should be paid to the significant genetic differentiation and diversity of the Omicron variant for better disease prevention and control.

Developing an electrolyte that is compatible with both high-voltage cathodes and Li metal anodes has always been challenging. Here, the authors created a new strategy by engineering a passivating electric double layer to achieve a fast-charging and lowtemperature high voltage lithium metal batteries.

In September 2011, Zhuonai Lake (ZL) in the northeast of Hoh Xil (HX) on the Qinghai–Tibet Plateau (QTP) broke out. The outburst event seriously changed the environmental hydraulics in this region. Due to the insufficient temporal resolution of observations, it is challenging to assess the impact of this event on short-period variations of water volumes in three lakes downstream of ZL. Combining multisource remote sensing data, we constructed long and high-temporal-resolution time series for the lake level, area, and lake water storage (LWS) of Kusai Lake (KL) to characterize the variabilities before and after the outburst. The water level, area, and LWS time series contain 1051 samples from 1990 to 2022, with uncertainties of 0.16 m, 2.5 km2, and 0.016 km3, respectively. The accuracies verified using the Database for Hydrological Time Series of Inland Waters (DAHITI) are 0.26 m, 2.64 km2, and 0.08 km3 for water level, area, and LWS, respectively. We characterized the LWS variations during the past 30 years based on the high temporal resolution LWS time series. Before the outburst, the 1-year and 3.5-year variations dominated the LWS time series, and there was no obvious semi-annual signal. After the outburst, the 3.5-year variation disappeared, and a strong semi-annual oscillation was observed. From 2012 to 2015, the periodic LWS variations in KL were disturbed by the ZL outburst and the subsequent outflow of KL led by the outburst. Regular cyclic signals have been restored since 2016, with an amplified annual fluctuation. By analysis, precipitation, evaporation, and glacier area change are excluded as driving factors of the pattern change in LWS variations of KL. It can be concluded that the altered recharge pattern of KL triggered by the outburst directly resulted in the observed changes in TWS behavior. For the first time, we identified the periodic patterns of LWS variations of KL during the past 30 years and revealed that the ZL outburst event significantly influenced these patterns. This finding contributes to the comprehensive understanding of the effects of the ZL outburst on downstream lake dynamics. Furthermore, the presented procedure for constructing long and high-resolution time series of LWS allows for monitoring and characterizing the short-period variabilities of Tibetan lakes that lack hydrological data.

ABSTRACT SARS-CoV-2 continues adapting to human hosts during the current worldwide pandemic since 2019. This virus evolves through multiple means, such as single nucleotide mutations and structural variations, which has brought great difficulty to disease prevention and control of COVID-19. Structural variation, including multiple nucleotide changes like insertions and deletions, has a greater impact relative to single nucleotide mutation on both genome structures and protein functions. In this study, we found that deletion occurred frequently in not only SARS-CoV-2 but also in other SARS-related coronaviruses. These deletions showed obvious location bias and formed 45 recurrent deletion regions in the viral genome. Some of these deletions showed proliferation advantages, including four high-frequency deletions (nsp6 Δ106-109, S Δ69-70, S Δ144, and Δ28271) that were detected in around 50% of SARS-CoV-2 genomes and other 19 median-frequency deletions. In addition, the association between deletions and the WHO reported variants of concern (VOC) and variants of interest (VOI) of SARS-CoV-2 indicated that these variants had a unique combination of deletion patterns. In the spike (S) protein, the deletions in SARS-CoV-2 were mainly in the N-terminal domain. Some deletions, such as S Δ144/145 and S Δ243-244, have been confirmed to block the binding sites of neutralizing antibodies. Overall, this study revealed a conservative regional pattern and the potential effect of some deletions in SARS-CoV-2 over the whole genome, providing important evidence for potential epidemic control and vaccine development. IMPORTANCE Mutations in SARS-CoV-2 were studied extensively, while only the structure variations on the spike protein were discussed well in previous studies. To study the role of structural variations in virus evolution, we described the distribution of structure variations on the whole genome. Conserved patterns were found of deletions among SARS-CoV-2, SARS-CoV-2-like, and SARS-CoV-like viruses. There were 45 recurrent deletion regions (RDRs) in SARS-CoV-2 generated through the integration of deleted positions. In these regions, four high-frequency deletions parallelly appeared in multiple strains. Furthermore, in the spike protein, the deletions in SARS-CoV-2 were mainly in the N-terminal domain, blocking the binding sites of some neutralizing antibodies, while the structural variations in SARS-related coronavirus were mainly in the N-terminal domain and receptor binding domain. The receptor binding domain is highly related to hosting recognition. The deletions in the receptor binding domain may play a role in host adaption.

Aflatoxins are naturally occurring high-toxic secondary metabolites, which cause worldwide environmental contaminations and wastes of food and feed resources and severely threaten human health. Thus, the highly efficient methods and technologies for detoxification of aflatoxins are urgently needed in a long term. In this work, we report the construction of recombinant Kluyveromyces lactis strains GG799(pKLAC1-Phsmnp), GG799(pKLAC1-Plomnp), GG799(pKLAC1-Phcmnp), and then the food-grade expression of the three manganese peroxidases in these strains, followed by the degradation of aflatoxin B1 (AFB1) using the fermentation supernatants. The expression of the manganese peroxidases was achieved in a food-grade manner since Kluyveromyces lactis is food-safe and suitable for application in food or feed industries. The inducible expression process of the optimal recombinant strain GG799(pKLAC1-Phcmnp) and the aflatoxin B1 degradation process were both optimized in detail. After optimization, the degradation ratio reached 75.71%, which was an increase of 49.86% compared to the unoptimized results. The degradation product was analyzed and determined to be AFB1-8,9-dihydrodiol. The recombinant strain GG799(pKLAC1-Phcmnp) supernatants degraded more than 90% of AFB1 in the peanut samples after twice treatments. The structural computational analysis for further mutagenesis of the enzyme PhcMnp was also conducted in this work. The food-grade recombinant yeast strain and the enzyme PhcMnp have potential to be applied in food or feed industries.

Multiwalled carbon nanotubes (MWCNTs) have excellent electronic, mechanical, and structural characteristics; however, their poor dispersion structure and large aggregates severely inhibit their function. A stable MWCNT dispersion in an aqueous solvent has been realized via ultrasonic dispersion and surfactant modification, providing a reference for improving MWCNT dispersion in various materials and solvents. In this study, a cyclic olefin copolymer with high transmittance to terahertz (THz) waves is used to prepare microfluidic chips. Then, the microfluidic and THz technologies are combined to study the THz absorption characteristics of MWCNT aqueous dispersion under different electric field (EF) intensities, magnetic field (MF) intensities, and MF action time. The results show that the THz spectral intensity of MWCNT aqueous dispersion decreases and the absorption coefficient increases with the increase of EF intensity, MF intensity, and MF action time. This phenomenon is explained from a microscopic perspective. The combination of microfluidic and THz technologies provides technical support for studying the characteristics of MWCNT aqueous dispersion and lays a foundation for elucidating the molecular microstructure of MWCNT aqueous dispersion.

Terahertz radiation enables nondestructive testing of biological samples, but is challenged by its high absorption in aqueous samples, so microfluidic technology is introduced to reduce the absorption. In this study, we designed a special temperature control device and an electric field device for a microfluidic chip to examine the terahertz spectral characteristics of konjac gum at different temperatures, concentrations, and electric field exposure time using the terahertz time domain spectroscopy system. Results demonstrate that higher concentrations of konjac gum lead to higher transmission intensity of terahertz radiation and a lower absorption of the radiation. Higher temperatures of the konjac gum lead to lower terahertz transmittance, and longer exposure time in the electric field leads to a lower transmittance of terahertz radiation and its higher absorption by the konjac gum. At the same time, we explain this phenomenon from the perspective of micromolecules. This study provides technical guidance for the detection of konjac gum by terahertz technology.

The unmanned aerial–underwater vehicle (UAUV) is a new type of vehicle that can fly in the air and cruise in water and is expected to cross the free water surface several times to perform continuous uninterrupted observation and sampling. To analyze the hydrodynamic and motion characteristics of the vehicle, the whole water-entry process of a multi-degree-of-freedom UAUV with various velocity and pitch angle was investigated through a Reynolds-averaged Navier–Stokes method. The computational domain was meshed by trimmer cells. The relative movement between the vehicle and fluid domain was simulated using moving reference frame overset mesh to delineate the interaction region around vehicle body. To reduce the computational cost, adaptive mesh refinement and adaptive time-stepping strategy were used to capture the slamming pressure accurately with reasonable computational effort. First, convergence study is considered. Simulations of the vehicle with various initial velocities and different pitch angles were performed. The variable physical properties were analyzed, and detailed results through the time-varying force and velocity were shown. Initial velocity and pitch angle are found to significantly influence hydrodynamic behavior, including the time-varying force, while thickness ratio has a great impact on added mass and pressure. The results show that higher entry velocity results in greater peak vertical force. The transverse hydrodynamic characteristics for oblique water entry of the vehicle with varies pith angle are quite different.

Neuroblastoma (NB) is a rare type of cancer but frequently occurred in children. However, it is still unclear whether circular RNAs (circRNAs) play key roles in NB tumorigenesis or progression. In this study, we identified 39,022 circRNAs across the 39 neuroblastoma and 2 normal cell lines. With the gene and circRNA expression data, we classified the NB cell lines, identified and characterized the functional circRNAs in the 3 NB classes. Specifically, 29 circRNAs were found to be dysregulated in the NB classes. Notably, 7 circRNAs located within MYCN-amplified regions were upregulated in cell lines with the high activities of MYC targets and MYCN amplification, and were highly correlated with expression of their parental gene, NBAS . Subsequently, we constructed ceRNA networks for the functional circRNAs. Specifically, hsa_circ_0005379 was identified as a critical regulator in the ceRNA networks because of targeting 13 genes, which formed a complex competing endogenous RNA (ceRNA) network. Moreover, hsa_circ_0002343, which was connected with few genes, might regulate the PI3K/Akt/mTOR signaling via RAC1. Furthermore, 3 genes, including NOTCH2, SERPINH1, and LAMC1, involved in epithelial mesenchymal transition (EMT) were observed to connect with hsa_circ_0001361, suggesting that this circRNA was closely associated with EMT. Consequently, 7 genes, such as DAD1, PPIA, NOTCH2, PGK1, BUB1, EIF2S1, and TCF7L2, were found to be closely associated with both event-free survival (EFS) and overall survival (OS). In conclusion, the present study identified functional circRNAs and predicted their functionality in neuroblastoma cell lines, which not only improved the understanding of circRNAs in neuroblastoma, but also provided the evidences for the related researchers.

Video recording is one of the most commonly used techniques for reflection, because video allows people to know what they look like to others and how they could improve their performance, but it is problematic because some people easily fall into negative emotions and worry about their performance, resulting in a low benefit. In this study, the possibility of applying a simple VR-based reflection method was explored. This method uses virtual reality (VR) and a head-mounted display (HMD) to allow presenters to watch their own presentations from the audience’s perspective and uses an avatar, which hides personal appearance, which has low relevance to the quality of presentation, to help reduce self-awareness during reflection. An experimental study was carried out, considering four personal characteristics—gender, personal anxiety, personal confidence and self-bias. The goal of this study is to discuss which populations can benefit more from this system and to assess the impact of the avatar and HMD-based VR. According to the results, the individuals with low self-confidence in their public speaking skills could benefit more on self-evaluation from VR reflection with HMD, while individuals with negative self-bias could reduce more anxiety by using an avatar.

Arbutin (also called β-arbutin) is a natural product occurring in the leaves of a variety of different plants, the bearberries of the Ericaceae and Saxifragaceae families being prominent examples. It is a β-glucoside derived from hydroquinone (HQ; 1,4-dihydroxybenzene). Arbutin has been identified in traditional Chinese folk medicines as having, inter alia, anti-microbial, anti-oxidant, and anti-inflammatory properties that useful in the treatment of different ailments including urinary diseases. Today, it is also used worldwide for the treatment of skin ailments by way of depigmenting, which means that arbutin is a component of many products in the cosmetics and healthcare industries. It is also relevant in the food industry. Hundreds of publications have appeared describing the isolation, structure determination, toxicology, synthesis, and biological properties of arbutin as well as the molecular mechanism of melanogenesis (tyrosinase inhibition). This review covers the most important aspects with special emphasis on the chemical and biocatalytic methods for the production of arbutin.