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Due to the low permeability of tight reservoirs, throats play a significant role in controlling fluid flow. Although many studies have been conducted to investigate fluid flow in throats in the microscale domain, comparatively fewer works have been devoted to study the effect of adsorption boundary layer (ABL) in throats based on the digital rock method. By considering an ABL, we investigate its effects on fluid flow. We build digital rock model based on computed tomography technology. Then, microscopic pore structures are extracted with watershed segmentation and pore geometries are meshed through Delaunay triangulation approach. Finally, using the meshed digital simulation model and finite element method, we investigate the effects of viscosity and thickness of ABL on microscale flow. Our results demonstrate that viscosity and thickness of ABL are major factors that significantly hinder fluid flow in throats.

Zinc ions (Zn2+) act as a transcription factor in eukaryotic cells for mediating protein-protein interactions in human healthy. The simple and sensitive detection of Zn2+ is the crucial mission in analytical field. This work demonstrated a novel and fast Zn2+ detection strategy based on “signal on” mode with electrochemiluminescence (ECL) luminophore, in which singlet oxygen was generated via electrocatalytic reduction of zinc proto-porphyrin IX grafted onto Pd nanocubes (ZnPPIX-Pd NCs). In protocol, Pd NCs were synthetized under hydrothermal conditions and aminated through thermal oxidative polymerization of 3-aminopropyltriethoxysilane (APTES), followed by further linking with PPIX via amide reaction. The resulting PPIX-Pd NCs effectively captured Zn2+ in chelation and monitored by Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV-vis) absorption spectroscopy. By virtue of the metal resonance responses of Pd NCs, an intense monochromic, potential shuffling and enhanced ECL irradiation shows up for the hybrid nanocomposite with H2O2 as the coreactant. To this end, an ultrasensitive method based on the nanocomposite with a “signal-on” model was developed for Zn2+ detection with a low detection limit down to 0.38 nM (based on a S/N= 3), excellent precision and high stability. The ECL strategy reveals the potential application in molecular diagnosis and offers a new avenue for bioassay of structural Zn(II) proteins and zinc finger-binding nucleotides.

Electrochemiluminescence (ECL) has attracted significant interest because of its superior properties and potential applications in bioanalysis, and therefore many luminescent nanomaterials have been developed. Herein, well-defined Pd nanocones (Pd NCs) were facilely obtained by a one-pot hydrothermal method with poly- l -lysine (PLL) as a green protecting ligand, which were mainly characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Then, the as-obtained Pd NCs were first explored as an anodic ECL emitter, where tripropylamine (TPA) worked as the coreactant to boost the ECL emission. The possible ECL mechanism of Pd NCs/TPA system was extensively explored by ECL and electrochemical techniques. Briefly, the ECL emission underwent the oxidation-reduction route, in which both Pd NCs and TPA were initially oxidized, and then the oxidized TPA lost an proton to form reducing agent (TPA·) strongly reacted with the oxidized Pd NCs generating Pd NCs* for the emission. Furthermore, using dopamine (DA) as an ECL quencher, an ultrasensitive sensor was constructed for DA detection. The fabricated ECL sensor shows high sensitivity and selectivity, good stability, and wide linear range with the low detection limit of 0.46 pM. It offers a new avenue to exploit ECL illuminant and enriches the ECL emission theory.

Organophosphate esters (OPEs) are widely used flame retardants that are frequently released into the environment, causing potential harm to humans and ecosystems. Tibet is located on the Tibetan Plateau, known as the “roof of the world”, but the occurrence of OPEs in Tibet remains unclear. This is the first report of the occurrence, potential sources and risks of 12 OPEs in water, soil, sediment and snow from Xainza, a typical town at high elevation in Tibet (average elevation = 4700 m). Ten OPEs were observed, with ∑OPE concentrations of 46.45–1744.73 ng/L in surface water, 29.74–73.85 ng/g in soil, and 13.30–32.23 ng/g in sediment. Moreover, the mean ∑OPE concentration in snow was 413.90 ng/L. Tris (2-chloroethyl) phosphate (TCEP) and tris (2-chloroisopropyl) phosphate (TCPP) were the main OPEs in surface water and snow, while 2-ethylhexyl diphenyl phosphate (EHDPP) was dominant in soil and sediment. Local human activities and long-distance atmospheric transport may be the main sources of OPEs in Xainza. The assessment of ecological risk indicated that EHDPP in soil poses potential risk. The occurrence of OPEs in Xainza showed that more attention should be paid to persistent organic pollutants in high-elevation regions.

Ischemic injury in the heart is associated with death of cardiomyocytes and even after decades of research there is no appropriate therapeutic intervention to treat ischemic injury. The microRNA miR-34a is known to be induced in cardiomyocytes following ischemic injury. Another hallmark of ischemic injury is impaired glycolysis. The objective of the current study was to investigate the effects of short- and long-term exposure to hypoxia on miR-34a expression on apoptosis and regulation of key glycolysis metabolic enzymes. Both repeated short-term (30 min) burst of hypoxia with intermittent reoxygenation (30 min) as well as long-term (4 h) exposure to hypoxia followed by 6 h of reoxygenation robustly induced miR-34a levels. Hypoxia induced changes in cardiac permeability and localization of the channel protein connexin 34 as well as induced apoptosis as evident by levels of cleaved-caspase 3/7 and impaired cell proliferation. Hypoxia was also associated with decreased expression of key glycolytic enzymes hexokinase-1, hexokinase-2, glucose-6-phosphate-isomerase, and pyruvate dehydrogenase kinase 1. Attenuation of hypoxia-induced miR-34a by anti-miR-34a antagomir, but not a control antagomir, decreased miR-34a levels to those observed under normoxia and also inhibited apoptosis, potentially by rescuing expression of the key glycolytic enzymes. Cumulatively, our results establish that therapeutic targeting of miR-34a via antagomir might be a potent therapeutic mechanism to treat ischemic injury in the heart.

with the development of space exploration, the resolution of optical system is required to be higher and higher. According to the Rayleigh criterion, the resolution of the optical system is directly proportional to the aperture. However, due to the influence of processing capacity and size of the rocket fairing, it is difficult to achieve one single large aperture. Therefore, the scheme of using small size segmented-mirror to achieve one large aperture becomes an effective form. Because location difference between the deployment and the ideal position, the imaging quality will be affected, and cannot be imaged in serious case. For the analysis of influence of the position error on the imaging quality, the traditional method is to analyze on the optical transfer function and Strehl ratio in theory, ignoring the influence of various aberrations that cannot be corrected by the optical system itself. In this paper, the segmented-mirror primary mirror system model is established to analyze the influence of the position error and the real influence of the various aberrations of the system, so as to complete the analysis of the influence more comprehensively. Through the analysis of different position errors, we can get the final wave-front aberration and Strehl ratio of the system under the influence of position error, which can be used as a reference for the analysis of position error influence of segmented-mirror primary mirror form and sparse aperture form of large aperture optical system in the future.

A structure of suppressing stray light of space-based infrared optical system was designed. In order to reduce the internal radiation, reflective baffles and traditional baffles were designed. The system of reflective baffles described here consist of vanes whose outward facing surfaces are ellipsoids and whose backward facing surfaces are hyperboloids of one sheet. Software tracepro was also used to build the system model and simulate analysis of the system. According to the simulated dates, the PST curve was drawn. The results indicate that stray light off axis was well suppressed. Thermal radiation of the system respectively at different temperature were also simulated. When the temperature was down below 115 K, the illumination of target that gets to imager is an order of magnitude higher than the internal thermal radiation that gets to imager. The results indicate that thermal radiation was also well suppressed.

Good application of metal-organic frameworks (MOFs) on uranium adsorption has attracted increasing attention recently. MIL-53(Al)-AO, synthesized by introducing amidoxime groups to MIL-53(Al)-NH2 aimed to adsorb U(VI), was characterized by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis and fourier transformed infrared spectroscopy. The sorption capacity of MIL-53(Al)-AO for U(VI) in aqueous solutions has been enhanced to 2.36 times compared with MIL-53(Al)-NH2 at pH 6.0 under the same conditions according to the experimental results, possibly due to the strong chelation of amidoxime. Effects of contact time, pH, interfering ions, and U(VI) concentration on the sorption of U(VI) for MIL-53(Al)-AO were also investigated. The sorption was strongly dependent on pH and independent of coexist ions. Result of this study shows that the MIL-53(Al)-AO was a kind of potential material to enrich U(VI) from aqueous solutions, and amidoxime could be introduced to MOFs sorbent by transforming the grafted amino groups on MIL-53(Al)-NH2.