Search

Background. Endothelial barrier disruption of human pulmonary vascular endothelial cells (HPVECs) is an important pathogenic factor for acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Mesenchymal stem cells-exosome (MSCs-Exo) represents an ideal carrier for cell-free therapy. The therapeutic implication and underlying mechanism of human placental MSCs-Exo (HPMSCs-Exo) in ALI/ARDS need to be further explored. Materials and Methods. HPMSCs-Exo was extracted from HPMSCs and characterized. Then, the therapeutic effects of exosomes were evaluated in ALI mice and HPVECs. RNA-sequencing was applied to reveal the miRNA profile of HPMSCs-Exo and differentially expressed genes (DEGs) in HPMSCs-Exo-pretreated HPVECs. The targets of miRNAs were predicted by bioinformatics methods and correlated to DEGs. Finally, the role of hsa-miR-148a-3p/ROCK1 pathway in HPVECs has been further discussed. Results. The results showed that HPMSCs-Exo could downregulate Rho-associated coiled-coil-containing protein kinase 1 (ROCK1), upregulate the expression of zonula occludens-1 (ZO-1) and F-actin, promote HPVECs migration and tube formation, reduce cytoskeletal disorders and cell permeability, and thus improve ALI/ARDS. RNA-sequencing revealed the DEGs were mainly enriched in cell junction, angiogenesis, inflammation, and energy metabolism. HPMSCs-Exo contains multiple miRNAs which are associated with cytoskeletal function; the expression abundance of hsa-miR-148a-3p is the highest. Bioinformatic analysis identified ROCK1 as a target of hsa-miR-148a-3p. The overexpression of hsa-miR-148a-3p in HPMSCs-Exo promoted the migration and tube formation of HPVECs and reduced ROCK1 expression. However, the overexpression of ROCK1 on HPVECs reduced the therapeutic effect of HPMSCs-Exo. Conclusions. HPMSCs-Exo represents a protective regimen against endothelial barrier disruption of HPVECs in ALI/ARDS, and the hsa-miR-148a-3p/ROCK1 pathway plays an important role in this therapeutics implication. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to examine the predictive ability of follicle‐stimulating hormone (FSH)/luteinizing hormone (LH) ratio and antimullerian hormone (AMH) levels in the same cohort when both are inconsistent and to identify which has an excellent ability to predict live birth and ovarian response to in vitro fertilization (IVF). Methods: A retrospective cohort study was performed within 6096 IVF cycles executed between January 2016 and August 2019 at the Center for Assisted Reproduction, The Third Affiliated Hospital of Zhengzhou University, and Jiaozuo Maternity and Child Health Care Hospital. Initially, IVF cycles were classified according to basal FSH/LH ratio and AMH values, and the primary outcome was a comparison of live birth rate per cohort. Secondary outcomes included characteristics of the study individuals such as body mass index (BMI), age, antral follicle count, ovarian sensitivity index, cycle cancellation rate, and cycle outcome data. Result(s): Women with FSH/LHhigh ratio and AMHnormal levels had a meaningly higher live birth rate compared with those with FSH/LHnormal ratio and AMHlow levels (46.59% vs. 21.21%, p < 0.001). In addition, women with FSH/LHnormal ratio and AMHlow levels were found to have a higher cancellation rate in their IVF cycles (80.98%). In women with FSH/LHnormal ratio, further multivariate analysis revealed that AMH level, age, number of retrieved oocytes, and FSH dosage were relevant risk factors for live birth. The relative risk of live birth was 0.11 (95% [CI] 0.06–0.20, p < 0.001) in patients with AMHlow compared with patients with AMHnormal. It also suggested that the probability of AMHlow level may be higher as the women's age (≥35 years, odd ratio [OR] 1.94, 95% [CI] 1.44–2.61; p < 0.001) and increasing BMI (≥28 kg/m2, OR 2.38, 95% [CI] 1.33–4.27; p = 0.004). Receiver operating characteristic curve analysis indicated that AMH had higher sensitivity and specificity to predict live birth compared with FSH/LH (AUC 0.627 vs. 0.539). Conclusion(s): AMH levels can be an excellent predictor of the discrepancy between FSH/LH ratio and AMH levels regarding living birth rates in women undergoing IVF. [ABSTRACT FROM AUTHOR]

The mineral oil (MO) in conjunction with paper is the main insulation components in oil-immersed transformers; their insulation properties play a significant role in the safe and stable operation of power transformers. To strengthen the insulation level of ultra-high voltage transformer and to reduce its size and weight, it is imminent to enhance the insulating performance of transformer oil and oil-impregnated cellulose. Recently, a unique novel effort of suspension of nanorods (NRs) into MO has been carried out and the results have exhibited improved insulation characteristics of transformer oil. The Al2O3 NRs with favorable features were prepared in our laboratory to develop transformer oil/paper insulation system with better insulation performance. The transformer oil-based nanofluids (NFs) were prepared with nanorod shape, oleic acid surface modification and 0.8 g/L concentration of NRs. The impregnated pressboards were prepared by impregnating them into dried oil and NF under vacuum beneath 1 kPa at 80 °C for almost 48 h to obtain the oil-impregnated pressboard (OIP) and nanofluid-impregnated pressboard (NIP), respectively. The interface at solid/liquid is considered weak link and is the main reason of oil-filled transformer collapse. The effect of Al2O3 NRs on creeping discharge and flashover traits of oil/pressboard (OP) interface under AC and impulse voltages were studied. Partial discharge and creeping flashover test of OIPs and NIPs were conducted. TSDC and PEA tests were applied to examine the space charge properties of OP interface before and after suspension of Al2O3 NRs. [ABSTRACT FROM AUTHOR]

Transformer pressboard impregnated in mineral oil modified by nanoparticles (nanofluid) exhibits substantially higher AC and DC breakdown voltage than that of the pure oil-impregnated pressboard (OP). Charge transport and decay characteristics of both pressboards were measured by pulse electroacoustic technique. It reveals that nanofluid-impregnated pressboard (NP) has a more uniform internal electric field and a higher charge decay rate compared to OP, which is caused by an increase of shallow trap density in NP related to the difference of internal structures, based on the test results of thermally stimulated current and Fourier transformed infra-red spectroscopy. [ABSTRACT FROM AUTHOR]

Transformer oil-based nanofluids with TiO2 semiconductive nanoparticles exhibit substantially higher AC and positive impulse breakdown voltage levels than that of pure transformer oils. Thermally stimulated current method (TSC) and pulse electroacoustic technique (PEA) have been used to measure charge trap and transportation characteristics of pure oils and nanofluids. It is found that electron shallow trap density and charge decay rate are greatly increased in nanofluids, i.e., fast electrons may be converted to slow electrons by electron trapping and de-trapping in shallow traps of nanofluids, resulting in improved breakdown performance compared to that of pure oil. [ABSTRACT FROM AUTHOR]

Recent studies have found that the surface flashover strength of oil-impregnated insulation paper can be improved by the modification of nanoparticles. To reveal the working mechanism, this paper presents an experimental study on the effects of TiO2 nanoparticles on streamer propagation process at the surface of oil-based nanofluid-impregnated insulation paper under lightning impulse voltage. The results show that the surface flashover voltage of nanofluid-impregnated insulation paper is significantly increased by 34.6%. Streamer characteristics including shape and length at the surface of oil-impregnated insulation paper were investigated using the schlieren technique. It is indicated that streamer characteristics are dramatically changed by the addition of TiO2 nanoparticles. For nanofluid-impregnated insulation paper, streamers with more but much shorter branches tend to develop into adjacent nanofluid rather than clinging to the paper compared to that for pure oil-impregnated paper. The reason responsible for the shape dissimilarity lies in the change of electrical force due to the permittivity difference between oil and paper. Furthermore, more shallow traps introduced by nanoparticles contribute to the faster surface charge dissipation of nanofluid-impregnated paper, reducing the charge accumulation at the streamer head and suppressing the electric field distortion. Thus, it is hard for streamers to develop at the surface of nanofluid-impregnated paper, resulting in an increase of surface flashover strength. [ABSTRACT FROM AUTHOR]

In this paper, prebreakdown streamers in transformer oil and transformer oil-based TiO2 nanofluid were observed by the schlieren method under positive lightning impulse voltage. Streamers in the nanofluid have numerous branches with much shorter length, whereas in the pure oil, they exhibit only certain filaments with longer length. The discrepancy in positive streamer pattern of both oils is further investigated under a range of applied voltages. The complexity of streamer patterns was quantitatively described using the fractal analysis method. Results indicate that the fractal dimension of streamer patterns shows different changing tendencies in both oils, and it keeps higher value in the nanofluid than that in pure oil during the whole propagation process, well corresponding with streamer propagating structures. Moreover, a new parameter, the ratio of fractal dimension to propagation length (D/L), is introduced to classify the complex streamer patterns for the first time. Three propagation zones in both nanofluid and pure oil are clearly categorized by the value of D/L, providing a quantitative way to distinguish the streamer patterns. [ABSTRACT FROM PUBLISHER]

Monodisperse Fe3O4nanoparticles modified by oleic acid were synthesized by a solvothermal method and dispersed into mineral transformer oil to prepare Fe3O4nanofluids. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis indicated that the obtained nanoparticles are single crystals with an average diameter of 15 nm. The test results indicate that the nanoparticles exhibited good dispersibility in the nanofluids at a wide range of concentrations. Moreover, the positive impulse breakdown strength of nanofluids was greatly improved by 36.6% at the optimum concentration of nanoparticles. [ABSTRACT FROM PUBLISHER]

This paper presents experimental research on creeping discharge characteristics of TiO2 nanofluid-impregnated pressboards (NPs) under sustained ac voltage. It was found that NPs possess higher resistance to creeping discharge than that of pure oil-impregnated pressboard. The results of permittivity and surface charge accumulation and decay characteristics reveal that the modification of nanoparticles can not only make the electric field more uniformly distributed at the interface of nanofluid/pressboard due to a better matching in permittivity but also significantly increase the surface charge decay rate via a trapping and detrapping process in shallower traps. Thus, the creeping discharge characteristics of NPs are greatly improved by the modification of TiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

Recent experiments have shown that some nanoparticles can influence the breakdown strength of transformer oil under lightning impulse voltage. To reveal the working mechanism, this paper presents an experimental study on the effect of TiO2 nanoparticles on the impulse breakdown strength and prebreakdown streamer propagation process in transformer oil-based nanofluid under both positive and negative lightning impulse voltage. The test results verify that the modification of nanoparticles on breakdown strength of transformer oil has a distinct polar effect: positive breakdown voltage of nanofluid is increased by up to 30.8%, whereas the negative one is decreased by 6.8%. Streamer shape, propagation length and velocity in both pure oil and nanofluid were investigated using the shadowgraph technique. It is revealed that the propagation characteristics of positive and negative streamers in nanofluid are markedly affected by the addition of TiO2 nanoparticles. The positive streamers in nanofluid form a bush-like structure with thicker and denser branches, developing much slower than tree-like streamers in pure oil. While negative streamers in nanofluid have a tree-like shape with much longer branches, propagating faster than the original bush-like streamer in pure oil. These differences in streamer propagation characteristics and breakdown strength in pure oil and nanofluid are closely related to the change of space charge distribution caused by shallow trap in nanofluid. More negative charges are formed through capturing fast electrons into slow electrons in shallow traps induced by the presence of TiO2 nanoparticles, which change the local electric field in front of the streamer tip. Thus, streamer propagation process in nanofluid is dramatically modified, leading to the change in breakdown strength. [ABSTRACT FROM AUTHOR]

The mineral oil or synthetic oil in conjunction with paper is mainly being applied as dielectric medium in many of the high voltage apparatus. However, the advent of high voltage levels such high voltage alternating current (HVAC) and high voltage direct current (HVDC) has prompted researchers to direct their focus onto an insulation system which can bear the rising high voltage levels. The modern insulating liquid material development is guided by various factors such as high electrical insulation requirements and other safety and economic considerations. Therefore transformer manufacturer companies have to design transformers with these new specific requirements. The transformer oil-based nanofluids with improved dielectric and thermal properties have the potential to replace mineral oil base products in the market place. They are favorable because they function more superior than mineral oil and they contribute definite insulating and thermal gains. This paper reviews recent status of nanofluids use as transformer oils. The nanofluids used as transformer oils are presented and their advantages are described in comparison with mineral oil. The multiple experimental works carried out by different researchers are described, providing an overview of the current research conducted on nanofluids. In addition scope and challenges being confronted in this area of research are clearly presented. [ABSTRACT FROM AUTHOR]

In order to improve dielectric performance of natural esters, TiO2 semiconductive nanoparticles were added to obtain an ester-based nanofluid. AC, lightning impulse voltage and partial discharge tests were applied to the natural ester and the ester-based nanofluid to check their dielectric performances. It was found that TiO2 nanoparticles can not only enhance AC breakdown voltage of the ester based nanofluid by a factor of 1.3 but also improve the partial discharge properties of the ester based nanofluid compared to that of the natural ester. Pulse electroacoustic (PEA) and thermally stimulated current (TSC) techniques were applied to investigate charge transport and trap characteristic in natural ester and ester-based nanofluid. It reveals that TiO2 nanoparticles can accelerate the charge dissipation rate and uniform the electric field and increase the shallow trap density in the ester-based nanofluid. It is proposed that electron trapping and de-trapping processes in the shallow traps could be one of the main charge transport processes in the ester based nanofluid. [ABSTRACT FROM AUTHOR]

Abstract: Transformer oil-based nanofluids (NFs) with TiO2 semiconductive nanoparticles (SNFs) exhibit substantially higher AC breakdown voltage than that of pure transformer oils at variable relative humidity from 20% to 80%. Charge accumulation and decay characteristics of pure oils and SNFs were measured by the pulse electroacoustic technique (PEA). It reveals that SNFs have more uniform internal electric fields and higher charge decay rate compared to pure oils under high relative humidity. It is confirmed by the test results of electrophoresis and thermally stimulated current (TSC) that the nanoparticles adsorb water molecules at the nanoparticle–oil interface, giving rise to the higher shallow trap density and resulting in better charge transport in SNFs. [Copyright &y& Elsevier]

Abstract: Well-crystalline ZnO nanorods were synthesized by a simple solution route employing dodecyl benzene sulfonic acid sodium salt (DBS) as a modifying agent. ZnO gas sensors were fabricated from ZnO nanorods with an average diameter of around 95nm and their gas-sensing properties were investigated. It was found that the sensors based on ZnO nanorods exhibit high responses and good selectivities to benzene and ethanol gas. Our results indicate that ZnO sensors will be promising candidates for practical detectors for dilute benzene and ethanol, respectively. [Copyright &y& Elsevier]

Abstract: Optical properties of ZnO star-shaped nanostructures grown by wet chemical solution method were investigated by using Raman scattering and temperature-dependent photoluminescence. High intensity of Raman mode with narrow FWHM of 9cm−1 appearing at 436cm−1 indicates the good quality of ZnO wurtzitic structure. Temperature-dependent ultraviolet photoluminescence was studied over the temperature range from 78 to 293K. At low-temperatures and low-excitation intensities, the dominant spontaneous emissions are due to radiative recombination of excitons bound to donors and one longitudinal optical phonon assistant free exciton A. Finally, only the first-order longitudinal–optical phonon replica of the A free exciton recombination was observed at room temperature. The exciton emission behaviour, including excitonic energy, intensity and line width dependents on the temperature and excitation intensities are discussed. The deep-level emission band is barely observable both at room temperature and at cryogenic temperature measurements. [Copyright &y& Elsevier]

Dolostone reservoirs are crucial for global oil and gas storage, holding a significant portion of hydrocarbon reserves within carbonate formations. Understanding the chemical mechanism of dolomite dissolution with organic acids and associated porosity development in these reservoirs is vital for optimizing hydrocarbon recovery. In this work, two sets of simulation experiments are designed to understand the controls of temperature and ionic effects on porosity enhancement during the dissolution of dolomite with acetic acid. In specific, we discovered a three-step reaction process between dolomite and acetic acid, involving acetic acid dissolution in water, acetic acid dissociation, and dolomite dissolution. Burial environments with higher temperatures reduce the degree of acetic acid dissociation, leading to a corresponding decrease in dolomite dissolution in acetic acid solutions. The presence of salt ions in the solution influences the reaction process, with magnesium chloride (MgCl 2) having the most significant enhancing effect on dolomite dissolution, followed by sodium chloride (NaCl), while calcium chloride (CaCl 2) has a limited impact. Sodium sulfate (Na 2 SO 4) enhances dolomite dissolution at lower temperatures; however, at higher temperatures (>100 °C), it may reduce dolomite dissolution due to the precipitation of CaSO 4. Despite a relatively short open-flow time, episodic burial dissolution of dolomite by acetic acid fluids under overburden pressure leads to a "net increase" in the reservoir space and enhances its connectivity attributes. During burial diagenesis, geological forces episodically drive organic acid fluids to the dolomite reservoir, predominantly dissolving dolomite along pre-existing pore development zones and geological interfaces, exhibiting inheritance, episodicity, and localization characteristics. Overall, this study provides insights into the dissolution and diagenetic processes of dolomite in the presence under acetic acids, from the point of dissolution simulation experiments. Collectively, these findings enhance our understanding of pore-system evolution and fluid-rock interactions in deep carbonate reservoirs. • Simulations reveal temperature and ions' effects on dolomite porosity in acetic acid. • Higher temperatures reduce acetic acid dissociation and dolomite dissolution. • Nonlinear response of dolomite dissolution under Na 2 SO 4 -contained acid with temperature. • Episodic acetic acid-dolomite dissolution enhances reservoir space and connection. [ABSTRACT FROM AUTHOR]

With the commencement of high voltage alternating current (HVAC) and high voltage direct current (HVDC), the demands on insulating reliability of power transformer is getting more and more imperative. The mineral oil (MO/TO) in conjunction with paper is the main insulation components in oil-immersed transformers; their insulation properties play a significant role in the safe and stable operation of power transformers. To strengthen the insulation level of ultra-high voltage transformer and to reduce its size and weight, it is imminent to enhance the insulating performance of transformer oil and oil-impregnated cellulose. Recently, a unique novel effort of suspension of nanoparticles (NPs) into mineral oil (MO) has been carried out and the results have exhibited improved insulation characteristics of transformer oil. The Al 2 O 3 nanoparticles with favorable features were prepared in our lab to develop transformer oil/paper insulation system with better insulation performance. The transformer oil-based nanofluids (NFs) were prepared with nanorod shape, oleic acid (OA) surface modification and 0.8 g/L concentration of NPs. The pressboards were cut into the desired sizes (85 mm.55 mm). The thickness of the pressboards was 2 mm applied in flashover tests. The prepared pressboards were put into an oven at 105 °C for almost 48 h to carry out the hot air drying operation. Then they were put in the vacuum drying at 85 °C for 48 h. The impregnated pressboards were prepared by impregnating them into dried oil and NF under vacuum beneath 1 kPa at 80 °C for almost 48 h to obtain the oil-impregnated pressboard (OIP) and nanofluid-impregnated pressboard (NIP) respectively. Additionally, the prepared insulation system samples of liquid (MO and NFs) and solid (OIPs, NIPs) were thermally aged at 130 °C for 30 days. The effect of alumina NPs on thermal aging of transformer oil and pressboard were also investigated. The results showed that Al 2 O 3 NPs can slow down the aging of oil and pressboard. The average AC and positive LI BDV of aged NFs was 11% higher than aged MOs. The average LI creeping FOVs of NIPs were 6% higher than OIPs. Additionally, average AC creeping FOVs of NIPs were 8% higher than that of OIPs. The enhancement in insulating performance of aged NFs and NIPs as compared to MO and OIPs is interpreted in light of electron traps theory. • Nanoparticles have the potential to influence the breakdown performance of oil/paper insulation system. • Suspension of Al2O3 nanoparticles may slow down the aging process of the oil/paper insulation system. • The enhancement in insulting performance of oil/paper insulation system may be interpreted in light of electron traps theory. [ABSTRACT FROM AUTHOR]

TiO2 nanoparticles can improve the electrical performance of oil paper insulation. In this study, 10 nm TiO2 nanoparticles were prepared and dispersed into transformer oil, and then immerse pressboards in it to obtain nanofluid impregnated pressboards (NP). Its thermal aging was accelerated together with the reference sample at 130°C for 36 days. Analyzing the acid value in the oil, polymerization degree, surface topography, AC breakdown strength, surface flashover characteristics and surface potential decay characteristics. It was observed that TiO2 nanoparticles can reduce the acid value and improve AC breakdown strength of oil. However, the degree of polymerization and surface appearance of NP and oil impregnated pressboards (OP) during thermal aging did not differ significantly. During the aging process, the energy level of pressboard surface traps shifted first towards the shallow and then gradually towards the deep. During all the aging stages, the surface flashover voltage of NP was always higher or close to that of OP. The mechanism of TiO2 nanoparticles improving the breakdown and surface flashover characteristics of oil–paper insulation during thermal aging is discussed from the perspective of water molecules and aging by‐products adsorption and introduction of shallow traps by nanoparticles. [ABSTRACT FROM AUTHOR]

TiO2 nanoparticle with good dispersibility and stability in transformer oil was prepared and used to modify insulating property of aged oil. It was found that space charge decay rate in the modified aged oil can be significantly enhanced to 1.57 times of that in the aged oil at first 8 s after polarization voltage was removed. The results of trap characteristics reveal that the modification of nanoparticle can not only greatly lower the shallow trap energy level in the aged oil but also increase the trap density, resulting in improved charge transportation via trapping and de-trapping process in shallower traps. [ABSTRACT FROM AUTHOR]

In this paper, TiO2 semiconductive nanoparticles with a large relaxation time constant is added into transformer oil to form semiconductive nanofluids (SNFs), with the aim of enhancing insulating characteristics. ac, dc and lightning impulse breakdown voltage and partial discharge (PD) characteristics of oil samples before and after modification were measured according to ASTM standard methods. It was found that SNFs have ac, dc and lightning impulse breakdown voltage up to 1.2 times compared with pure oil. Meanwhile, the partial discharge resistance of SNFs was also dramatically improved. Charge trap and transportation characteristics of both samples have been measured by thermally stimulated current method (TSC) and pulse electroacoustic technique (PEA). It was found that electron shallow trap density and charge decay rate are greatly increased in semiconductive nanoparticles modified transformer oil. It is proposed that electron trapping and de-trapping processes in the shallow traps could be one of the main charge transport processes in dielectric liquids. [ABSTRACT FROM PUBLISHER]

The phenolic adhesive and casein adhesive are two kinds of adhesives used in pressboard block production. The partial discharge characteristics of pressboard block containing the two types of adhesives under AC, DC and AC/DC composite voltage are researched in this paper. Using the block samples with phenolic adhesive or casein adhesive, the partial discharge characteristics, flashover characteristics and the influence of the adhesive layer orientations were obtained. The results show that the use of adhesive may introduce a weak zone of insulation performance and reduce the insulation strength of the pressboard block. There exist polar effects on partial discharge and flashover characteristics under DC voltage, and there is no significant difference in the partial discharge characteristics and flashover voltages between the pressboard blocks with casein and phenolic adhesive. The phenomena are analyzed in terms of molecular characteristics of adhesives and cellulose pressboard. The research results of this paper provide significant theoretical and practical reference for the optimization of transformer insulation materials. [ABSTRACT FROM AUTHOR]

Abstract: An icephobic surface is always desirable for high voltage overhead transmission lines to reduce ice formation on their aluminum surface, especially in a low temperature and high humidity environment. This work studied the effects of two hydrophobic coatings when applied on aluminum surfaces under cold and raining conditions in an artificial climatic chamber. Compared with bare hydrophilic aluminum surfaces, the aluminum surfaces coated with hydrophobic room temperature vulcanized silicone rubber (RTV SR) did resist ice formation but was covered by a layer of ice after 30min of spraying supercooled water. However, a superhydrophobic coating can largely prevent ice formation on the surface except a few ice growth spots at a working temperature of −6°C. Furthermore, such coating keeps average water contact angles larger than 150° even at a working temperature of −10°C. This highly icephobic performance of the above samples is mainly attributed to the superhydrophobic property of the coating, which was obtained on micronanoscale structured aluminum surfaces after the low surface-energy stearic acid treatment. [Copyright &y& Elsevier]

Background: Impaired endometrial receptivity is a major reason for embryo implantation failure. There's a paucity of information regarding the role of circRNAs on endometrial receptivity. Here, we investigated the function of hsa_circ_001946 on endometrial receptivity and its mechanisms. Methods: A total of 50 women composing 25 with recurrent implantation failure and 25 who conceived after their implantation were recruited in this study. Expression of hsa_circ_001946, miR-135b, and HOXA10 was evaluated by quantitative RT-PCR (qRT-PCR) in biopsied endometrial tissue samples. The levels of HOXA10, and cell cycle markers (CCNB1, CDK1, and CCND1) were determined by IHC and western blotting assays. Binding relationship among miR-135b, hsa_circ_001946 and HOXA10 were confirmed by dual luciferase reporter assays and western blotting. MTT assays and cell cycle assays by FACS were employed to evaluate the proliferation and cell cycle of cells. T-HESCs were cultured with 1 µM medroxyprogesterone acetate (MPA) and 0.5 mM 8-bromoadenosine 3':5'-cyclic monophosphate (8-Br-cAMP) to induce decidualization. The mechanisms and functions of hsa_circ_001946 on decidualization were further assessed by qRT-PCR evaluating the expression of hsa_circ_001946, miR-135b, HOXA10 and decidual markers (PRL and IGFBP1) in T-HESCs. Results: Endometrial tissues from patients with recurrent implantation failure had lower hsa_circ_001946 expression, higher miR-135b expression, and lower HOXA10 expression. Hsa_circ_001946 promoted HOXA10 expression by sponging miR-135b in T-HESCs. Overexpression of hsa_circ_001946 restored cell proliferation and cell cycle that were disrupted by miR-135b overexpression in T-HESCs. Decidualized T-HESCs had higher hsa_circ_001946 expression, lower miR-135b expression, and higher HOXA10 expression. Overexpression of hsa_circ_001946 reversed the expression of decidual markers (PRL and IGFBP1) that were suppressed by miR-135b overexpression in T-HESCs. Conclusions: In conclusion, our findings suggest that hsa_circ_001946 promotes cell proliferation and cell cycle process and increases expression of decidualization markers to enhance endometrial receptivity progression via sponging miR-135b and elevating HOXA10. [ABSTRACT FROM AUTHOR]

Transformer oil-based nanofluid-impregnated pressboard (NIP) with TiO 2 nanoparticles has been previously shown to exhibit substantially higher AC breakdown strength than that of pure oil-impregnated pressboard (OIP). In this study, OIP and NIP with TiO 2 nanoparticles were prepared and experiments on DC breakdown strength of were performed. It was found that NIP possesses higher resistance to DC breakdown strength than that of OIP. To reveal the working mechanism, a pulsed electro acoustic (PEA) device was used to measure the space charge accumulation and dissipation characteristics in OIP and NIP. The results show that the density of deep level traps in NIP is visibly reduced owing to the addition of TiO 2 nanoparticles and homopolar space charge accumulation on both sides of NIP is suppressed. Moreover, the charges injected from electrodes into NIP under DC voltage is also restrained owing to the increase of the Schottky potential barrier. Thus, the DC breakdown performance of NIP is considerably improved. [ABSTRACT FROM AUTHOR]

Four-electron process and the interference of Cl- make sluggish kinetics on oxygen evolution reaction (OER) for seawater electrolysis. Herein, NiFe LDH grown on NiFe-foam with CeO 2 modification and (W 2 O 7)2- intercalation was synthesized by one-step hydrothermal method. It only needs 353.8 and 386.7 mV to achieve a large current density of 1000 mA·cm−2 in 1 M KOH and alkaline natural seawater, respectively. The catalytic material can stand 100 h with a retention of 98.1% at 1000 mA·cm−2 in alkaline natural seawater. Experiments and theoretical calculations confirm that the state-of-the-art OER activity comes from the introduced CeO 2 with optimized adsorption energy of intermediates. The improved stability and selectivity in seawater can be ascribed to the preferential adsorption of Ni and Fe with higher valence on OH- based on hard and soft acid based (HSAB) principle by (W 2 O 7)2- intercalation. This work provides a viable approach to develop efficient catalytic material for large-current seawater electrolysis. NiFe LDH nanosheets with (W 2 O 7)2- intercalation and CeO 2 modification show state-of-the-art large-current seawater-electrooxidation performance contributed partially from introduced CeO 2 adjusting adsorption energy of intermediates during OER process, partially from preferential adsorption of OH- on metal active sites based on hard and soft acid based (HSAB) principle by (W 2 O 7)2- intercalation. [Display omitted] • NiFe LDH nanosheets with (W 2 O 7)2- intercalation and CeO 2 modification have been successfully synthesized. • It only needs an overpotential of 386.7 mV to achieve 1000 mA cm−2 in alkaline natural seawater electrocatalysis. • (W 2 O 7)2- intercalation enhances OH- selectivity and CeO 2 modification optimizes adsorption energy towards OER intermediates. [ABSTRACT FROM AUTHOR]

Nanoparticles have exhibited great potential in improving insulating property of liquid and solid dielectrics. To explore their modification mechanism on transformer oil-impregnated pressboards, TiO2 nanoparticles with different diameters of 5nm, 10nm, and 15nm were synthesized and used to prepare transformer oil-based nanofluids. The creeping flashover characteristics of both pure oil-impregnated paperboards (OPs) and nanofluid-impregnated pressboards (NPs) were examined under lightning impulse and AC voltages. It was found that the creeping flashover property of NPs is significantly improved with the decreasing of nanoparticle size. Especially, it is enhanced by 2.44 times under positive lighting impulse as nanoparticle size reduced from 15 nm to 5 nm. The results of space charge decay and trap characteristics reveal the decrease of nanoparticle size can lower trap depth and greatly enhance the space charge dissipation rate, leading to more uniform electric field distribution at the interface between nanofluid and pressboards and higher creeping flashover property. [ABSTRACT FROM AUTHOR]

The polarity reversal test is one of the routine tests for the evaluation of electric insulation in converter transformers. The polarity reversal time (PRT) has significant effect on the accumulation of interface charges in oil-impregnated pressboard insulation. IEC standard recommends that polarity reversal should be performed within 2 min so as to match with the dispersion rate of interface charges in uniform filed, but not necessarily in the non-uniform field. In order to investigate the influence of PRT on the dissipation rate of interface charges in non-uniform electric field, the density of interface charges was measured by an electrostatic capacitance probe in the needle-plate non-uniform field at the PRT of 2 ms, 4 ms and 2 min respectively. The results showed that the polarity of interface charges did not change with the applied voltage jump at the PRT of 2 ms and 4 ms, while the polarity of interface charges almost synchronously changed with the polarity reversal of applied voltage at the PRT of 2 min. For the PRT of 2 ms and 4 ms, the electric field nearby the needle electrode would be enhanced with applied electric field of the same direction, whilst the total electric field of insulation system would be weakened at the PRT of 2 min. It was inferred that polarity of interface charge might have not enough time to change in polarity reversal test within the PRT of 4 ms under non-uniform electric field, which was more close to the severe condition of covert transformer. The paper suggest that the value of PRT be reconsidered when the polarity reversal test is performed in non-uniform electric field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compositional regulation by introducing MoS 2 provides rich H adsorption sites. • Internal electronic regulation in heterostructure accelerates the RDS in OER process. • MnCo 2 S 4 @MoS 2 employed as a bifunctional catalyst for efficient hydrogen production. • Operating stably in industrial condition with structural reconstruction at the anode. • The electron redistribution and reaction pathways are explained by DFT calculations. It remains to be challenging to develop bifunctional catalysts for overall water splitting (OWS) with high activity and durability at large current density. In an attempt to overcome this bottleneck, unique MnCo 2 S 4 hexagonal stars covered with MoS 2 nanosheets were in-situ grown on nickel foam (NF) to obtain MnCo 2 S 4 @MoS 2 /NF heterostructure with optimized composition and local electronic structure in this work. When employed as a bifunctional catalyst, it only needs low overpotentials of 208 and 332 mV in 6.0 M KOH to drive 1000 mA cm−2 with small Tafel slopes of 56.8 and 75.6 mV dec-1 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. In addition, MnCo 2 S 4 @MoS 2 /NF showed remarkable stability in simulated industrial conditions, operating stably for 50 h at 1000 mA cm−2 without any attenuation for HER/OER. Thus, the MnCo 2 S 4 @MoS 2 /NF can function as a bifunctional electrocatalyst for OWS, only requiring 1.795 V to afford 1000 mA cm−2 with splendid stability. The improved performance is ascribed to dual electric and compositional regulation, which endow MnCo 2 S 4 @MoS 2 /NF with rich active sites and heterointerfaces, thereby promoting electron transfer and boosting the reaction kinetic. Furthermore, density functional theory (DFT) calculations reveal that the construction of heterostructure can help regulate intrinsic electronic structure, resulting in accelerated reaction kinetics. This work provides a reasonable and meaningful method for boosting industrial green hydrogen production. [ABSTRACT FROM AUTHOR]

The relationship between the permittivity of a two-phase porous composite material and its structure forms the basis for the adjustment and analysis of the permittivity of the porous material. However, existing calculation models exhibit significant errors at low frequencies. A wide-frequency equivalent model is proposed in this paper based on the geometrical structural characteristics of porous materials, considering the effects of interface polarization and dielectric relaxation process. The relationship between the two-phase porosity material and the dielectric response of its framework and filling medium in a wide-frequency range can be calculated. Furthermore, the modified Cole–Cole model is adopted to analyze the dielectric spectrum characteristics of cellulose and aramid, thereby exhibiting the effects of polar bonds in the molecular structure and impurity ions in the material on the polarization strength and polarization process. The results obtained from this study can provide key parameters and a basis for the analysis of the polarization process of two-phase combined porous materials and the design of low-permittivity insulating paper. [Display omitted] [ABSTRACT FROM AUTHOR]

Low-temperature preparation of efficient electron transport layer (ETL) can effectively expand the application of perovskite solar cells (PSCs). We herein introduce anatase TiO 2 nanoparticles (NPs) with an average diameter of 15 nm prepared by hydrothermal method and optimized with acetic acid (AA) as well as oleic acid (OA). The Ti3+ as well as Ti–OH signals indicate the surface defects of TiO 2 NPs investigated by X-ray photoelectron spectroscopic (XPS) are observed to be passivated by the modifiers through chelate or bridging pattern. Thus, when the modified NPs are dispersed into the precursor for spin-coating ETLs under 150 °C, higher power conversion efficiency (PCE) of 20.15% and 19.41% is achieved based on planar structured PSC using TiO 2 modified with AA and OA, respectively. The device stability is also considerably increased. Analyzed by photoluminescence and electrochemical impedance spectroscopies, the improved cell performance can be ascribed to the reduced charge transport resistance, enhanced electron extraction, and suppressed recombination behavior. We anticipate this facile approach of fabricating efficient TiO 2 ETLs can be further employed into PSCs commercialization. [ABSTRACT FROM AUTHOR]

The adhesion of ice to high -voltage overhead transmission lines should be small to ensure ease of ice shedding under small external forces. In this work, we studied the influence of the microstructure of superhydrophobic surfaces on the strength of ice adhesion at a working temperature of --6 °C. Compared to a bare aluminum surface, the microstructure superhydro-phobic aluminum surfaces did decrease ice adhesion strength. The superhydrophobic alumi-num surfaces with a larger number of micro-holes produced the lowest strength of ice adhesion; its ice adhesion strength was ~163.8 times lower than that for the bare aluminum samples. Furthermore, such microstructure aluminum surfaces had water contact angles larger than 150° and water sliding angles of less than 8.2° even at a working temperature of --6°C. The low values of the ice adhesion strength of the above samples were mainly attributed to the superhydrophobic property, which was obtained by creating a structure of micro-nano-scale holes on the aluminum surface after treatment with a low- surface-energy fluoroalkylsi-lane (FAS). [ABSTRACT FROM AUTHOR]

Creeping flashover of mineral-oil-impregnated pressboard under impulse stress is a common insulating failure in oil-immersed transformers, arousing increasing attention. Recent studies have shown that the breakdown strength of transformer oil under positive lightning impulse voltage can be significantly improved through nanoparticles-based modification, and Fe3O4 has shown the best improvement in breakdown strength compared to other nanoparticles that have been used. This paper presents the creeping flashover characteristics of pure oil-impregnated pressboard (OIP) and nanofluid-impregnated pressboard (NIP) based on Fe3O4 nanoparticles under positive and negative lightning impulse voltages, respectively. It was found that NIP possessed higher resistance to creeping flashover than OIP. The relative permittivities of oil and oil-impregnated pressboard before and after nanoparticles-based modification were measured, and the results revealed that the addition of nanoparticles led to a better match in relative permittivity between oil and oil-impregnated pressboard, and a more uniform electric field distribution. Furthermore, the shallow trap density in NIP was obviously increased compared to that of OIP through the thermally stimulated depolarization current (TSDC), which promoted the dissipation of surface charges and weakened the distortion of the electric field. Therefore, the creeping flashover characteristics of oil-impregnated pressboard were greatly improved with Fe3O4 nanoparticles. [ABSTRACT FROM AUTHOR]

Polarization and traps determine the electrical property of oil-paper insulation, but most attention has been paid to the modification of insulating oil with nanoparticles, so there are is little research about oil-impregnated paper, and the origin for performance variation is not understood yet. In this paper, spherical nanoscale titanium dioxide was prepared by the hydrolysis method and nanofluid-impregnated paper (NP) was fabricated through oil-impregnation. The frequency domain spectrum was measured for polarization analysis, and both thermally stimulated depolarization current (TSDC) and isothermal surface potential decay (ISPD) methods were used to reveal trap parameters. Results show that NP's low frequency permittivity is much larger, and another peak appears in the spectrum even though the content of nanoparticles is very low. With the addition of TiO2 nanoparticles, TSDC's amplitude and peak temperature increase, and the trap energy becomes shallower. TiO2 nanoparticles' strong polarization and high activation energy contribute to NP's larger interface polarization intensity and activation energy. Furthermore, because of oxygen vacancies, TiO2 nanoparticles offer a transfer site for holes and electrons to escape from deep traps; thus, the trap energy is greatly reduced. [ABSTRACT FROM AUTHOR]