•This paper proposes an improved grey wolf optimization (IGWO) for optimizing KELM.•A new hierarchical mechanism was established in the proposed IGWO.•Effectiveness of IGWO strategy is validated on ...functions and three practical applications.•Experimental results reveal the improved performance of the proposed algorithm.
Since its introduction, kernel extreme learning machine (KELM) has been widely used in a number of areas. The parameters in the model have an important influence on the performance of KELM. Therefore, model parameters must be properly adjusted before they can be put into practical use. This study proposes a new parameter learning strategy based on an improved grey wolf optimization (IGWO) strategy, in which a new hierarchical mechanism was established to improve the stochastic behavior, and exploration capability of grey wolves. In the proposed mechanism, random local search around the optimal grey wolf was introduced in Beta grey wolves, and random global search was introduced in Omega grey wolves. The effectiveness of IGWO strategy is first validated on 10 commonly used benchmark functions. Results have shown that the proposed IGWO can find good balance between exploration and exploitation. In addition, when IGWO is applied to solve the parameter adjustment problem of KELM model, it also provides better performance than other seven meta-heuristic algorithms in three practical applications, including students’ second major selection, thyroid cancer diagnosis and financial stress prediction. Therefore, the method proposed in this paper can serve as a good candidate tool for tuning the parameters of KELM, thus enabling the KELM model to achieve more promising results in practical applications.
Premature leakage of photosensitizer (PS) from nanocarriers significantly reduces the accumulation of PS within a tumor, thereby enhancing nonspecific accumulation in normal tissues, which inevitably ...leads to a limited efficacy for photodynamic therapy (PDT) and the enhanced systematic phototoxicity. Moreover, local hypoxia of the tumor tissue also seriously hinders the PDT. To overcome these limitations, an acidic H2O2‐responsive and O2‐evolving core–shell PDT nanoplatform is developed by using MnO2 shell as a switchable shield to prevent the premature release of loaded PS in core and elevate the O2 concentration within tumor tissue. The inner core SiO2‐methylene blue obtained by co‐condensation has a high PS payload and the outer MnO2 shell shields PS from leaking into blood after intravenous injection until reaching tumor tissue. Moreover, the shell MnO2 simultaneously endows the theranostic nanocomposite with redox activity toward H2O2 in the acidic microenvironment of tumor tissue to generate O2 and thus overcomes the hypoxia of cancer cells. More importantly, the Mn(ΙΙ) ion reduced from Mn(ΙV) is capable of in vivo magnetic resonance imaging selectively in response to overexpressed acidic H2O2. The facile incorporation of the switchable MnO2 shell into one multifunctional diagnostic and therapeutic nanoplatform has great potential for future clinical application.
Premature leakage of photosensitizer (PS) from nanocarriers reduces the accumulation of PS within tumor, leading to a limited efficacy for photodynamic therapy (PDT). Moreover, local hypoxia of tumor also seriously hinders the PDT. To overcome these limitations, an acidic H2O2‐responsive MnO2 shell is introduced to prevent the premature release of PS and simultaneously elevate O2 concentration within the tumor.
Today's state‐of‐the‐art perovskite solar cells (PSCs) are utilizing polycrystalline perovskite thin films via solution‐processing at low temperature (<150 °C). It is extremely significant to enlarge ...grain size and passivate trap states for perovskite thin films to achieve high power conversion efficiency. Herein, a strategy for defect passivation of perovskite films via metal ion Ni2+ is for the first time reported. It is found that addition of Ni2+ can significantly generate polyporous PbI2 films due to a different solubility between NiCl2 and PbI2 which benefits penetration of MAI and thus formation of large grain perovskite films eventually. It further demonstrated that Ni2+ ions can effectively passivate PbI3− antisite defects and restrain the generation of Pb0 by interacting with the under‐coordinated halide anions and halide‐rich antisites. Therefore, introducing moderate Ni2+ ions result in a significant increase in photoluminescence lifetime from 285 to 732 ns. Accordingly, a power conversion efficiency of 20.61% can be achieved for the 3% Ni2+ addition‐based PSCs with an enhanced cell stability under ambient conditions. This work provides a promising route toward perovskite films featuring with high crystallinity and low trap‐density.
An effective strategy of promoting grain growth and defects passivation simultaneously for perovskite film by using Ni2+ addition is demonstrated. An appreciated efficiency of 20.6% can be achieved for an inverted planar perovskite solar cells device based on a CH3NH3PbI3 (Ni2+) film.
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•Carboxyl functionalized Ti3C2Tx MXene (TCCH) was synthesized.•The stability of the TCCH in water was significantly improved compared with raw Ti3C2Tx.•The optimized TCCH showed ...superior U(VI) and Eu(III) adsorption capacities up to 334.8 mg/g and 97.1 mg/g, respectively.•The adsorption mechanism was associated with inner-sphere surface complexation and electrostatic interaction.
With the development of nuclear power, the negative environmental impact such as radioactive pollution has become an urgent issue to impede the utilization of nuclear energy. The construction of promising organic-inorganic hybrid materials is considered as an effective strategy for environmental remediation of radioactive contamination. In this work, two-dimensional transition metal carbide (MXene), an emerging inorganic layered material, has been successfully modified by carboxyl terminated aryl diazonium salt to both enhance its chelating ability to radionuclides and improve its water stability. The carboxyl functionalized Ti3C2Tx MXene (TCCH) shows excellent removal ability for U(VI) and Eu(III), evidenced by ultrafast adsorption kinetics (3 min), high maximum adsorption capacities (344.8 mg/g for U and 97.1 mg/g for Eu) and high removal percentage of radionuclides from artificial groundwater (> 90%). The adsorption of U(VI) and Eu(III) on TCCH are in good accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. Ionic strength experiments, X-ray photoelectron spectroscopy (XPS) and Extended X-ray absorption fine structure (EXAFS) analyses were conducted to assess the detailed adsorption mechanism. The results reveal that the adsorption of U(VI) on TCCH follows an inner-sphere configuration, whereas the adsorption of Eu(III) is determined by both inner-sphere complexation and electrostatic interaction.
Abstract
Background
Emerging evidence has shown that circular RNAs (circRNAs) play a crucial regulatory role in the occurrence and development of cancer. Exploring the roles and mechanisms of ...circRNAs in tumorigenesis and progression may help to identify new diagnostic markers and therapeutic targets. In the present study, we investigated the role and regulatory mechanism of hsa_circ_0004872 in gastric cancer (GC).
Methods
qRT-PCR was used to determine the expression of hsa_circ_0004872 in GC tissues and cells. EdU, CCK-8, transwell and scratch wound healing assays were used to assess the role of hsa_circ_0004872 in GC cell proliferation, invasion and migration, respectively. Subcutaneous and tail vein tumor injections in nude mice were used to assess the role of hsa_circ_0004872 in vivo. RIP assay, biotin-coupled probe pull-down assay, FISH and luciferase reporter assay were performed to confirm the relationship between hsa_circ_0004872 and the identified miRNA. ChIP assay, luciferase reporter assay and western blot were used to determine the direct binding of Smad4 to the promoter of the ADAR1 gene.
Results
In this study, we found that hsa_circ_0004872 was dramatically downregulated in GC tissues compared with adjacent noncancerous tissues. The expression level of hsa_circ_0004872 was associated with tumor size and local lymph node metastasis. Enforced expression of hsa_circ_0004872 inhibited the proliferation, invasion and migration of GC cells, whereas knockdown of hsa_circ_0004872 had the opposite effects. Nude mice experiments showed that ectopic expression of hsa_circ_0004872 dramatically inhibited tumor growth and metastasis in vivo. Moreover, we demonstrated that hsa_circ_0004872 acted as a “molecular sponge” for miR-224 to upregulate the expression of the miR-224 downstream targets p21 and Smad4. Importantly, we found that the RNA-editing enzyme ADAR1 inhibited hsa_circ_0004872 expression and further led to the upregulation of miR-224. Smad4, the downstream target of miR-224, could further affect hsa_circ_0004872 levels by directly binding to the promoter region of ADAR1 to inhibit ADAR1 expression.
Conclusions
Our findings showed that hsa_circ_0004872 acted as a tumor suppressor in GC by forming a negative regulatory loop consisting of hsa_circ_0004872/miR-224/Smad4/ADAR1. Thus, hsa_circ_0004872 may serve as a potential biomarker and therapeutic target for GC.
The development of new techniques and materials that can separate ethylene from ethane is highly relevant in modern applications. Although adsorption-based separation techniques using metal–organic ...frameworks (MOFs) have gained increasing attention, the relatively low stability (especially water resistance) and unscalable synthesis of MOFs severely limit their application in real industrial scenarios. Addressing these challenges, we rationally designed and synthesized two new C2H6-selective MOF adsorbents (NKMOF-8-Br and -Me) with ultrahigh chemical and thermal stability, including water resistance. Attributed to the nonpolar/hydrophobic pore environments and appropriate pore apertures, the MOFs can capture C2 hydrocarbon gases at ambient conditions even in high humidity. The single-crystal structures of gas@NKMOF-8 realized the direct visualization of adsorption sites of the gases. Both the single-crystal data and simulated data elucidate the mechanism of selective adsorption. Moreover, the NKMOF-8 possesses high C2H6 adsorption capacity and high selectivity, allowing for efficient C2H6/C2H4 separation, as verified by experimental breakthrough tests. Most importantly, NKMOF-8-Br and -Me can be scalably synthesized through stirring at room temperature in minutes, which confers them with great potential for industrial application. This work offers new adsorbents that can address major chemical industrial challenges and provides an in-depth understanding of the gas binding sites in a visual manner.
The dissolved oxygen level of the low-latitude Pacific thermocline is a sensitive tracer of global ocean circulation, especially at high latitudes. However, its variability covering ...glacial–interglacial cycles has not been well documented. Based on the thermocline-dwelling foraminiferal population extracted from Calypso Core MD06–3047, we derived a record of the Western Tropical Pacific (WTP) thermocline oxygenation over the last 700 kyr. We found that the glacial thermocline oxygenation gradually enhanced to dome-like peaks during glacial periods, with significant relative abundance of thermocline-dwelling species minimum events. We suggest that the remote physical process of lateral O2 supply (dominated by Southern Ocean (SO) ventilation and Antarctic Intermediate Water advection, with a minor contribution of North Pacific Intermediate Water (NPIW)) and the local biological process of O2 consumption (by organic biological productivity, determined by iron supply and NPIW-driven nutrient supply) may together control the WTP thermocline oxygenation on glacial–interglacial cycles. The surprisingly synchronous co-variation indicates that SO ventilation and Antarctic Intermediate Water advection have the potential to be the primary controlling factors. Furthermore, the consistent and simultaneous dramatic increments in Marine Isotope Stages 13–11 transition and each deglacial period provide robust support for a close coupling between the global (mid-Brunhes) climatic shift scenario of SO ventilation and the WTP thermocline oxygenation.
•Deglacial enhanced oxygenation in the Western Tropical Pacific (WTP) thermocline have existed since at least ∼700 ka.•The remote physical and the local biological processes may together control WTP thermocline oxygenation on glacial–interglacial cycles.•Southern Ocean ventilation and the WTP thermocline oxygenation have a close coupling in mid-Brunhes climatic shift scenario.
In this work, CeO2 NRs were synthesized by a hydrothermal approach and their microstructures were controlled by modifying the concentration of the hydroxide ions. The as-synthesized CeO2 NRs appeared ...highly crystallized with a cubic structure, while their lengths increased from ∼20 to 50 nm as the concentration of the hydroxide ions increased. By tuning their surface properties, the CeO2 NR samples exhibited favorable band structures, which enabled them to effectively absorb large amount of photon energies and enhance the photocatalytic properties. The optimum CeO2 sample showed the highest H2 production rate (∼25.10 μmol/g after solarlight irradiation for 5 h), largest Brunauer-Emmett-Teller specific surface area (65.26 m2/g), smallest pore size (7.0 nm), and largest amount of oxygen vacancies. The photocatalytic H2 evolution properties were attributed to the preferred planes of the CeO2 NRs and the redox capacity of CeO2. The photocatalytic process is mainly related to the conversion of Ce3+/Ce4+ cycle of CeO2, and the redox capability of CeO2 is related to the amount of its oxygen vacancies.
•The heterogeneous CeO2 nanorods (NRs) were synthesized by using a facile hydrothermal method.•The surface performances of CeO2 NRs were effectively tuned by hydroxide ions.•The favorable heterogeneous structure of CeO2 NRs attributed to the wider range of solar light absorption.•The optimum CeO2 sample shows about 25.10 μmol g−1 H2 production within 5 h.•The amount of oxygen vacancies of CeO2 affects the catalytic behavior.
Geogenic As enrichment is prevalent in freshwater systems worldwide, yet the connection between such enrichment and regional tectonics remains poorly understood, especially within orogenic ...environments like the Tibetan Plateau. To provide new insights into the sources and processes of arsenic, as well as its relationship with tectonics in the plateau basin, we selected the Yarlung Tsangpo basin, situated at the collision zone between the Indian (Himalaya block) and Eurasian plates (Lhasa block) as the study area. We analyzed and compared the chemical compositions of waters and sediments across various litho-tectonic domains. This also involved assessing arsenic concentrations in river waters, suspended particulate matter (SPM), sediments, geothermal waters, and rocks. The main findings are as follows: (a) High-arsenic geothermal waters and igneous rocks are common in the Lhasa block, and the discharge of these geothermal waters is the main source of dissolved As in river water, whereas erosion of igneous rocks contributes most of the As in sediments. (b) Metal oxides adsorb dissolved As, which leads to further As enrichment in the sediments. (c) The occurrence of high As concentrations in the southern Tibetan Plateau can be explained by a crustal cycling model. Arsenic likely originated in Neo-Tethys oceanic crustal rocks and was concentrated in the upper crust of the active continental margin (Lhasa block) during geological cycling at convergent plate boundaries. These studies highlight the role of tectonic settings on influencing arsenic enrichment in the plateau basin.
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•Geothermal water discharge in the Lhasa block identified as the primary source of dissolved arsenic.•Erosion of magmatic rocks in the Lhasa block contributes the majority of arsenic found in sediments.•Adsorption onto metal oxides further increases arsenic enrichment in sediments.•A crustal recycling model explains the arsenic enrichment in shallow crustal materials of the southern Tibetan Plateau.
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