Clarifying the evaluation methods and factors influencing shale brittleness is of great practical significance for fracture mechanism analysis, rock mass stability evaluation, geophysical ...interpretation, ”sweet spot” engineering optimization, and exploration risk assessment. This paper comprehensively analyses and discusses the evaluation methods and factors influencing shale brittleness. This study shows that the methods for evaluating shale brittleness mainly include the rock stress–strain relationship, brittle minerals, and comprehensive evaluation methods. The factors influencing shale brittleness include internal geological and external environmental factors. The internal factors are mainly the type and content of brittle minerals, the content and maturity of organic matter, rock bedding, porosity, etc. In contrast, the external factors are the temperature and confining pressure environment under the controls of burial depth and horizontal geostress differences. These factors control the stress–strain characteristics, mechanical properties, and fracture characteristics of shale to different degrees, thereby affecting shale brittleness. Therefore, the combination of experimental testing and geophysical interpretation, the development of dynamic visualization technology, and the establishment of a geological evaluation model should be given more attention in the future to provide a reference for shale compressibility evaluation and optimization of favourable fracturing target intervals.
Phosphors emitting visible and near-infrared persistent luminescence have been explored extensively owing to their unusual properties and commercial interest in their applications such as ...glow-in-the-dark paints, optical information storage, and in vivo bioimaging. However, no persistent phosphor that features emissions in the ultraviolet C range (200-280 nm) has been known to exist so far. Here, we demonstrate a strategy for creating a new generation of persistent phosphor that exhibits strong ultraviolet C emission with an initial power density over 10 milliwatts per square meter and an afterglow of more than 2 h. Experimental characterizations coupled with first-principles calculations have revealed that structural defects associated with oxygen introduction-induced anion vacancies in fluoride elpasolite can function as electron traps, which capture and store a large number of electrons triggered by X-ray irradiation. Notably, we show that the ultraviolet C afterglow intensity of the yielded phosphor is sufficiently strong for sterilization. Our discovery of this ultraviolet C afterglow opens up new avenues for research on persistent phosphors, and it offers new perspectives on their applications in terms of sterilization, disinfection, drug release, cancer treatment, anti-counterfeiting, and beyond.
The clinical features and immune responses of asymptomatic individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been well described. We studied 37 ...asymptomatic individuals in the Wanzhou District who were diagnosed with RT-PCR-confirmed SARS-CoV-2 infections but without any relevant clinical symptoms in the preceding 14 d and during hospitalization. Asymptomatic individuals were admitted to the government-designated Wanzhou People's Hospital for centralized isolation in accordance with policy
. The median duration of viral shedding in the asymptomatic group was 19 d (interquartile range (IQR), 15-26 d). The asymptomatic group had a significantly longer duration of viral shedding than the symptomatic group (log-rank P = 0.028). The virus-specific IgG levels in the asymptomatic group (median S/CO, 3.4; IQR, 1.6-10.7) were significantly lower (P = 0.005) relative to the symptomatic group (median S/CO, 20.5; IQR, 5.8-38.2) in the acute phase. Of asymptomatic individuals, 93.3% (28/30) and 81.1% (30/37) had reduction in IgG and neutralizing antibody levels, respectively, during the early convalescent phase, as compared to 96.8% (30/31) and 62.2% (23/37) of symptomatic patients. Forty percent of asymptomatic individuals became seronegative and 12.9% of the symptomatic group became negative for IgG in the early convalescent phase. In addition, asymptomatic individuals exhibited lower levels of 18 pro- and anti-inflammatory cytokines. These data suggest that asymptomatic individuals had a weaker immune response to SARS-CoV-2 infection. The reduction in IgG and neutralizing antibody levels in the early convalescent phase might have implications for immunity strategy and serological surveys.
The large-scale development and utilization of shale gas is significant for achieving the “Carbon Peak and Carbon Neutrality” goals. However, addressing the ecological environmental challenges ...stemming from extensive hydraulic fracturing is imperative. Drawing from the successful exploration and development of shale gas in the Sichuan Basin, this paper employs a bibliometric approach and utilizes the Web of Science database as its data source to review the impact of shale gas development on the ecological environment. Furthermore, effective strategies for achieving coordinated development of shale gas benefit exploitation and ecological environmental conservation in China are identified. The findings highlight that the ecological impact of shale gas development has been a major focus of research over the past decade, primarily involving concerns such as water resources consumption, groundwater pollution, methane emissions, and waste management. These challenges can be addressed by adopting measures such as responsible water usage, maintaining well integrity, proper storage and disposal of fracturing flowback fluids, and appropriate management of drilling solid waste. The key to achieving green and efficient shale gas development in China lies in constructing a solid theoretical framework for benefit exploitation, refining environmental management standards and regulations, and promoting the development of clean production technologies specific to shale gas. Additionally, establishing a distinct exploration and development theory and fostering technical innovation for deep shale gas (buried depth > 3500m) are pivotal for enhancing and stabilizing production in China. Clarifying the theoretical logic of benefit development and improving the environmental protection law of shale gas development are of great significance for realizing the scale benefit development of shale gas and the harmonious development of ecological environment in China.
Triboelectric nanogenerators (TENGs) are a promising technology to convert mechanical energy to electrical energy based on coupled triboelectrification and electrostatic induction. With the rapid ...development of functional materials and manufacturing techniques, wearable and implantable TENGs have evolved into playing important roles in clinic and daily life from in vitro to in vivo. These flexible and light membrane‐like devices have the potential to be a new power supply or sensor element, to meet the special requirements for portable electronics, promoting innovation in electronic devices. In this review, the recent advances in wearable and implantable TENGs as sustainable power sources or self‐powered sensors are reviewed. In addition, the remaining challenges and future possible improvements of wearable and implantable TENG‐based self‐powered systems are discussed.
Wearable and implantable triboelectric nanogenerators (TENGs) are developed for harvesting biomechanical energy, which can be used for sustainable power sources and self‐powered biosensors in vitro and in vivo. Research advances for these TENGs with different electric performance and the corresponding applications are discussed in detail. The perspectives on the challenges and solutions for these TENGs are proposed.
Electronic devices with various functions bring great convenience and revolutionize the way we live. They are inevitable to degrade over time because of physical or chemical fatigue and damage during ...practical operation. To make these devices have the ability to autonomously heal from cracks and restore their mechanical and electrical properties, self‐healing materials emerged as the time requires for constructing robust and self‐healing electronic devices. Here the development of self‐healing electronic devices with different functions, for example, energy harvesting, energy storage, sensing, and transmission, is reviewed. The new application scenarios and existing challenges are explored, and possible strategies and perspectives for future practical applications are discussed.
Self‐healing technology can restore the structure and electrical performance of electronic devices from damage, effectively improving the reliability and service life. Self‐healing materials, structure design strategies, and working performances of self‐healing electronic devices are reviewed. The challenges and possible strategies for the future development of self‐healing electronic devices are emphasized.
Self-powered implantable medical electronic devices that harvest biomechanical energy from cardiac motion, respiratory movement and blood flow are part of a paradigm shift that is on the horizon. ...Here, we demonstrate a fully implanted symbiotic pacemaker based on an implantable triboelectric nanogenerator, which achieves energy harvesting and storage as well as cardiac pacing on a large-animal scale. The symbiotic pacemaker successfully corrects sinus arrhythmia and prevents deterioration. The open circuit voltage of an implantable triboelectric nanogenerator reaches up to 65.2 V. The energy harvested from each cardiac motion cycle is 0.495 μJ, which is higher than the required endocardial pacing threshold energy (0.377 μJ). Implantable triboelectric nanogenerators for implantable medical devices offer advantages of excellent output performance, high power density, and good durability, and are expected to find application in fields of treatment and diagnosis as in vivo symbiotic bioelectronics.
Soft wearable electronics for underwater applications are of interest, but depend on the development of a waterproof, long-term sustainable power source. In this work, we report a bionic stretchable ...nanogenerator for underwater energy harvesting that mimics the structure of ion channels on the cytomembrane of electrocyte in an electric eel. Combining the effects of triboelectrification caused by flowing liquid and principles of electrostatic induction, the bionic stretchable nanogenerator can harvest mechanical energy from human motion underwater and output an open-circuit voltage over 10 V. Underwater applications of a bionic stretchable nanogenerator have also been demonstrated, such as human body multi-position motion monitoring and an undersea rescue system. The advantages of excellent flexibility, stretchability, outstanding tensile fatigue resistance (over 50,000 times) and underwater performance make the bionic stretchable nanogenerator a promising sustainable power source for the soft wearable electronics used underwater.
We report acute antibody responses to SARS-CoV-2 in 285 patients with COVID-19. Within 19 days after symptom onset, 100% of patients tested positive for antiviral immunoglobulin-G (IgG). ...Seroconversion for IgG and IgM occurred simultaneously or sequentially. Both IgG and IgM titers plateaued within 6 days after seroconversion. Serological testing may be helpful for the diagnosis of suspected patients with negative RT-PCR results and for the identification of asymptomatic infections.
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