Nanodevices have potential as intelligent sensing systems for detection of microRNAs (miRNAs) in living cells. However, the resolution offered by “always active” nanodevices is often insufficient to ...manipulate miRNA sensing with high spatiotemporal control. In this work, using DNA nanotechnology we constructed an activatable DNA nanodevice programmed to detect miRNAs in vitro and in vivo with the high spatial and temporal precision of NIR light. Our nanodevice is functionalized on the surface of upconversion nanoparticles (UCNPs) with a rationally designed DNA beacon that displays UV light-activatable miRNA sensing activity. The UCNPs absorb deep-tissue-penetrable NIR light and emit high-energy UV light locally, which serve as transducers to operate the nanodevice in the NIR window. The nanodevice can naturally enter cells and enable remote regulation of its fluorescent imaging activity for miRNAs in living cells by NIR light illumination in a chosen place and time. Furthermore, we demonstrate that the nanodevice can be expanded to activatable imaging of intratumoral miRNAs in living mice. This work illustrates the potential of DNA nanodevices for miRNA detection with high spatiotemporal resolution, which could expand the toolbox of technologies for precise biological and medical analysis.
Shale gas is a major component of the hydrocarbon economy, and there are abundant studies in related exploration and exploitation fields using simulations and experiments. In this paper, the kinetic ...processes of adsorption and displacement during shale gas exploitation are analyzed using enthalpy-driven and entropy-driven processes with molecular dynamics simulations and statistical mechanics analyses. First, the changes in symmetry of CH4 and CO2 adsorbed on the graphene surface are analyzed. The adsorption process is a spontaneous process, where the Gibbs free energy decreases. During this process, the gas molecular entropy and the enthalpy of the system decrease, which indicates an enthalpy-driven process. The changes in entropy and enthalpy of various gas molecules (CH4, CO2, N2, and H2O) during the adsorption process are obtained. Through comparing the entropy and enthalpy changes before and after the displacement of CH4 by the different displacement media (CO2, N2, and H2O). The CO2-injected displacement of CH4 is driven by both enthalpy and entropy, and the N2-injected displacement of CH4 is driven by entropy. However, H2O-injected displacement of CH4 is not a spontaneous process. It plays a certain displacement role by reducing the partial pressure of CH4. To clarify the detailed spontaneous processes, the entropy change and exothermic processes during the supercritical fluid displacement of shale gas are discussed; then, the differences in displacement efficiency of different supercritical fluids are explained. This study is useful for understanding the kinetics mechanism of adsorption and displacement of shale gas.
•Entropy changes of molecules during adsorption and displacement are analyzed.•Enthalpy and free energy changes of the CH4 displacement by different molecules are analyzed.•The spontaneous and exothermic processes during the displacement of shale gas are determined.•A new perspective to explain the efficiency of supercritical fluids in displacing shale gas is provided.
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•The limiting heat of CH4 adsorption on graphene has been obtained.•Adsorption properties of CH4 on graphene have been clarified.•We provide a direct evidence of graphene as a model ...of shale in simulations.
In this paper, we explored material similarity between graphene and shale for methane (CH4) adsorption in the shale gas recovery simulations. The reasons of choosing graphene to model shale have been clarified. Through theoretical analysis, we obtained the attenuation law of interaction potential between CH4 and multilayer graphene. It indicates the adsorption energy of CH4 on monolayer graphene is closest to that on shale. The limiting heat of adsorption of CH4 on graphene was calculated by molecular dynamics (MD) simulation. The adsorption isotherms and adsorption heats on the monolayer graphene, whose width of the slit pore ranges from 2nm to 11nm, were calculated by using grand canonical Monte Carlo (GCMC) simulations at different temperatures. The computed adsorption heat is validated by experimental data, which indicates that the adsorption properties of CH4 on shale are quite similar with that of CH4 on graphene. Our study may provide a direct evidence of using graphene in modeling shale in simulating the shale gas adsorption/desorption.
Sepsis-associated cerebral dysfunction is complex pathophysiology, generated from primary infections that are developed elsewhere in the body. The neonates, elderly population and chronically ill and ...long-term hospitalized patients are predominantly vulnerable to sepsis and related cerebral damage. Generally, electrophysiological recordings, severity and sedation scales, computerized imaging and spectroscopy techniques are used for its detection and diagnosis. About the underlying mechanisms, enhanced blood-brain barrier permeability and metalloprotease activity, tight junction protein loss and endothelial cell degeneration promote the influx of inflammatory and toxic mediators into the brain, triggering cerebrovascular damage. An altered neutrophil count and phenotype further dysregulate the normal neuroimmune responses and neuroendocrine stability via modulated activation of protein kinase C-delta, nuclear factor kappa-B and sphingolipid signaling. Glial activation, together with pro-inflammatory cytokines and chemokines and the Toll-like receptor, destabilize the immune system. Moreover, superoxides and hydroperoxides generate oxidative stress and perturb mitochondrial dynamics and ATP synthesis, propagating neuronal injury cycle. Activated mitochondrial apoptotic pathway, characterized by increased caspase-3 and caspase-9 cleavage and Bax/Bcl2 ratio in the hippocampal and cortical neurons, stimulate neurocognitive impairments. Additionally, altered LC3-II/I and P62/SQSTM1, p-mTOR, p-AMPK1 and p-ULK1 levels and dysregulated autophagosome-lysosome fusion decrease neuronal and glial energy homeostasis. The therapies and procedures for attenuating sepsis-induced brain damage include early resuscitation, cerebral blood flow autoregulation, implantable electric vagus nerve stimulation, antioxidants, statins, glucocorticoids, neuroimmune axis modulators and PKCδ inhibitors. The current review enumerates the pathophysiology of sepsis-induced brain damage, its diagnosis, the role of critical inducers and mediators and, ultimately, therapeutic measures attenuating cerebrovascular degeneration.
Shale gas stored in deep shale is in a supercritical state. Therefore, it is necessary to study the adsorption and desorption properties of supercritical shale gas. To accurately determine the state ...of methane (CH4) in the pores of deep shale, the fractal characteristics of several shale samples drilled at a depth of 2650 m are analyzed using scanning electron microscopy (SEM) and image analysis. We find nanopores with different fractal features in the shale. The effects of adsorption energy and substrate strain on adsorption capacity are clarified. The virial coefficients of CH4 are obtained by molecular dynamics (MD) simulations and are consistent with the experiment. The adsorption and desorption of CH4 in different fractal nanopores are modeled using grand canonical Monte Carlo (GCMC) simulations at different temperatures and pressures (from capillary condensation to supercritical state). Additionally, the gas-in-place (GIP), excess adsorption, and absolute adsorption isotherms are obtained. We find the crossover of excess adsorption isotherms, which was observed in the experiment, and the absolute adsorption amount increases with the increase in pressure in the case of ultrahigh pressure (>40 MPa). Moreover, we obtain an ultrahigh-pressure dual-site Langmuir equation, and it can accurately describe observed adsorption isotherms from low pressure to ultrahigh pressure. Our study visually reproduces the adsorption/desorption behaviors of CH4 under in situ conditions in deep shale and reveals their microscopic mechanism.
The decay of soil strength and the change of soil infiltration characteristics caused by the dry and wet cycle effect generated by the rainfall-evaporation process are important factors that induce ...slope instability. How to consider the effect of soil strength decay and water-soil characteristic curve hysteresis effect on transient stability change of slope is the key to solve this problem. In this paper, transient stability analysis of slopes considering soil strength decay and water-soil characteristic curve hysteresis is carried out based on Geo-Studio. The results of the study showed that the change of transient safety factor of the slope caused by rainfall-evaporation dry and wet cycle process has an overall decreasing trend and the safety factor decreased by 43% compared to the initial state. The seepage characteristics of the rainfall-evaporation dry-wet cycle have certain regularity. The location of slope measurement points has a greater influence on the magnitude of the pore pressure change: foot of slope > middle of slope > top of slope. Also, there is a significant response hysteresis in the change of pore pressure with increasing depth at the same location. The rainfall intensity has a certain influence on the change of slope safety factor, but its influence is not obvious when the rainfall intensity exceeds a certain amount.
The shale revolution has provided abundant shale oil/gas resources for the world, but the efficient, sustainable, and environmentally friendly exploitation of shale oil/gas is still challenging. ...Kerogen is the primary hydrocarbon source of shale oil/gas. The research on the kerogen chemo-mechanical properties significantly influences the development of shale oil/gas extraction technology. Rapid reconstruction of the kerogen molecular models is the most effective way to study the generation mechanism of shale oil/gas from the bottom-up molecular level. However, due to the combinatorial explosion problem, the reconstruction complexity of kerogen increases sharply because of the kerogen’s characteristics of complex origin, large molecular weight, and diverse functional groups. The traditional kerogen molecular reconstruction methods require professionals to comprehensively analyze various experimental information to approximate the actual kerogen molecular models through trial-and-error. So, the traditional methods are time and material-consuming and extremely inefficient. These shortcomings make researchers spend too much strength on the reconstruction of kerogen molecular models and cannot focus on the study of kerogen chemo-mechanical properties. For the past few years, state-of-the-art machine learning (ML) methods have been applied to intelligently reconstruct the kerogen molecular models through high-throughput and predict shale oil/gas production mechanisms. Although the current work is still in the infancy stage, ML methods are believed to be the most promising way to solve the drawbacks of traditional methods and reconstruct kerogen in reliable and large molecular weight. Hence, mechano-energetics is proposed to study the efficient development and utilization of energy based on mechanics and ML. This paper briefly reviews the development history of kerogen molecular model reconstruction methods and the research of ML in the fields of kerogen reconstruction and shale oil/gas exploitation. Some recommendations for further ML-based work are also suggested. We are convinced that the ML methods will accelerate the research of kerogen and promote the significant development of unconventional oil/gas exploitation technologies.
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