We propose a Michelson ultrasonic sensing system for detecting the acoustic emission generated by the partial discharge in power transformer. In order to guide the sensor head design in the sensing ...system for high sensitivity, a theoretical model is established to investigate the effects of the sensor head dimensions on the response sensitivity. After that, an optimized sensor head is designed. In the frequency range from 80 kHz to 200 kHz, whether the PZT sensor is installed in the oil or on the tank, the average response sensitivity of the proposed sensing system is higher than that of the conventional PZT system. When the distance between the sensor head and ultrasonic source is 300 mm in oil, the average detection limit of the Michelson ultrasonic sensing system is about 0.26 Pa, which is about 18.6% of that of the PZT system. Moreover, experiment results show that the detectable partial discharge initial voltage for the proposed optical system is 21.5% lower than that for the PZT system. The enhanced sensitivity makes the Michelson ultrasonic sensing system a potential method to detect the small defects in power transformer.
Energy and fresh water are essential for the sustainable development of human society, and both could be obtained from seawater. Herein, we explored the first covalent organic framework (COF) sponge ...(named BHMS) by in situ loading the benzoxazole-linked COF (DBD-BTTH) onto a porous polymer scaffold (polydimethylsiloxane) as a synergistic platform for efficient solar desalination and selective uranium recovery. In natural seawater, BHMS shows a high evaporation rate (1.39 kg m–2 h–1) and an exceptional uranium recovery capacity (5.14 ± 0.15 mg g–1) under 1 sun, which are due to its desirable inbuilt structural hierarchy and elastic macroporous open cells providing adequate water transport, increased evaporation sites of seawater, and selective binding sites of uranyl. Besides, the excellent photothermal performance and photocatalytic activity endow the BHMS with high solar desalination efficiency and excellent anti-biofouling activity and promote selective coordination of uranyl.
Galloping of overhead transmission lines (OHTLs) may induce conductor breakage and tower collapse, and there is no effective method for long distance distribution on-line galloping monitoring. To ...overcome the drawbacks of the conventional galloping monitoring systems, such as sensitivity to electromagnetic interference, the need for onsite power, and short lifetimes, a novel optical remote passive measuring system is proposed in the paper. Firstly, to solve the hysteresis and eccentric load problem in tension sensing, and to extent the dynamic response range, an 'S' type elastic element structure with flanges was proposed. Then, a tension experiment was carried out to demonstrate the dynamic response characteristics. Moreover, the designed tension sensor was stretched continuously for 30 min to observe its long time stability. Last but not the least, the sensor was mounted on a 70 m conductor model, and the conductor was oscillated at different frequencies to investigate the dynamic performance of the sensor. The experimental results demonstrate the sensor is suitable for the OHTL galloping detection. Compared with the conventional sensors for OHTL monitoring, the system has many advantages, such as easy installation, no flashover risk, distribution monitoring, better bandwidth, improved accuracy and higher reliability.
Mercury is one of the most toxic elements in the environment. Recently, a number of covalent organic frameworks (COFs) were developed for simultaneous detection and removal of mercury. They rely on ...post-synthetically modified sulfur-based ligands for irreversible mercury binding. In addition, their rigid structures resulted in low fluorescence yields. Herein, a novel highly luminescent COF named TFPPy-CHYD with a quantum yield of 13.6% was designed by integrating a pyrene-based building block with a flexible carbohydrazide linker. The nitrogen-based ligand allows reversible and highly selective binding of Hg2+. As a sensing platform, it has an ultralow detection limit of 17 nM mercury. More importantly, TFPPy-CHYD exhibits excellent performance in removing mercury from both air and water, providing very high Hg0 and Hg2+ adsorption capacities of 232 and 758 mg g–1, respectively. This work demonstrates enormous potential of luminescent COF for metal detection and remediation. By rational introducing metal ligands, a suite of new COF materials might be synthesized for the detection and removal of other metal ions.
PM2.5 samples were collected at an urban site (WD) and a suburban site (TH) in Wuhan from August 2012 to July 2013. The mass concentrations of water-soluble inorganic ions, carbonaceous species and ...elements of PM2.5 were measured. The annual mean concentrations of PM2.5 were 106.5μg/m3 and 114.9μg/m3 at WD and TH, respectively. The chemical compositions of PM2.5 at WD were similar to those at TH and the fractions of the major components of PM2.5 in Wuhan were in the following order of trace elements<chloride<EC (elemental carbon)<ammonium<nitrate<soil dust<sulfate<OM (organic matter). As the secondary ionic aerosols (SIA) and dominant ions, SO42−, NO3− and NH4+ all exhibited strong seasonal distributions, consistently with the lowest values in summer and the highest in winter. OM was the most abundant component in PM2.5, the lowest concentrations of which were observed in summer at both sites, while the highest concentrations of OC (organic carbon) appeared in winter at WD and autumn at TH, respectively. The highest OC concentration observed in autumn was tightly related to the biomass burning near the suburban site. The crustal elements (Mg, K, Ca and Fe) dominated the 20 detected elements in PM2.5, with the highest concentrations in spring in Wuhan, which might be due to frequent sandstorm from north carrying abundant soil dusts in spring in China. Ten trace elements (Cu, Ga, Ag, Tl, Ca, As, Zn, Pb, Se and Cd) were enriched in PM2.5 and the higher EF for Ag, Pb, Se and Cd in PM2.5 indicated that the air pollution from vehicle exhaust emission and coal burning in Wuhan was serious and noteworthy.
•PM2.5 is a pollutant of regional concern in Wuhan, Central China.•The mass concentrations of water-soluble inorganic ions, carbonaceous species and elements of PM2.5 were measured.•The air pollution from vehicle exhaust emission and coal burning in Wuhan was serious and noteworthy.
We proposed a strategy to synergistically enhance uranium capture capacity through photothermal desalination, and prepared a COF hydrogel (KTG) through a simple process for the first time. KTG with ...ideal broadband light absorption capacity could be used as an outstanding photothermal conversion material. Meanwhile, the built-in elastic honeycomb structure endowed the KTG with good mechanical properties and adequate water transport performance that accelerated the diffusion and mass transfer ability of uranyl. Under a simulated sunlight, the adsorption capacity, selectivity, adsorption rate and cycle capacity of uranium could be significantly improved. Moreover, benefiting from the outstanding photocatalytic performance, KTG exhibited a high anti-fouling activity against marine biological entities, thereby achieving long-term efficient uranium adsorption and solar desalination.
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•The first example of COF hydrogel for solar desalination and uranium recovery.•COF hydrogel for synergistically enhance uranium capture through photothermal desalination.•COF hydrogel shows a high evaporation rate and exceptional uranium recovery capacity.•COF hydrogel has high anti-biofouling activity and good reusability.
Capturing of uranium from the natural seawater is considered to be one of the most promising methods to meet the current demand for nuclear energy. Herein, we prepared a reduced graphene oxide-based (rGO-based) covalent organic framework hydrogel (KTG) with three-dimensional porous structure as a platform for enhancing uranium capture capacity through photothermal desalination. Under light irradiation, the KTG produces a local heat that can be used to generate steam while promoting the rapid diffusion of uranium inside the hydrogel 3D network, thereby increasing the adsorption efficiency and capacity of uranium. KTG can achieve exceptional uranium capture capacity (521.6 mg g−1) under one sun irradiation, which is 42.4% higher than that under dark conditions. In addition, excellent photocatalytic activity and mechanical properties make KTG possess high anti-biofouling activity, good reusability, and achieving continuous uranium capture and solar distillation.
Covalent organic framework nanosheets (COF NSs) provide well-ordered π–π structures that can be used to develop luminescent materials. However, most COF NSs have problems of weak luminescence and low ...fluorescence quantum yield. In this work, we prepared covalent organic framework nanosheets (Bpy-NSs) with good water dispersibility, nitrogen-rich functional groups, and regular pore structure. We explored the coordination of Bpy-NSs with Al3+ to eliminate the fluorescence quenching process caused by photoinduced electron transfer (PET). Thus, the fluorescence “turn-on” signal linearly increases with Al3+ concentration, achieving a 15.7-fold improved in fluorescence, and the absolute fluorescence quantum yield increased from 0.15 to 1.74%. Furthermore, this is the first COF fluorescence sensor that can be used for high sensitivity and selectivity detection of Al3+ in the aqueous phase. We anticipate that the expansion of metal ions coordination strategy in the aqueous phase will not only significantly enhance the fluorescence of COF NSs but also extend the functional range of COF NSs.
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•High selectivity imidazole was introduced as linkage in varying degree hydroxylation covalent organic polymers.•Benefiting from the introduction of hydroxyl groups, the uranium ...adsorption capacities were largely enhanced.•The TpDAB endowed prominent selectivity towards multiple metal ions including vanadium.•The hydroxyl groups significantly influenced the uranium coordination mechanism of imidazole functional group.
Highly effective and reliable adsorbents for uranium extraction are vital significant for environmental protection and social development. Herein, inspired by the interaction between imidazole affinity ligand of histidine and uranium, a series of varying degree hydroxylation imidazole linked covalent organic polymers were developed for the first time via one step facile reaction without any post treatment between 2,4,6-triformylphloroglucinol (Tp), 2,4,6-triformylresorcinol (Bd), 2,4,6-triformylphenol (Hb) and 3,3′-diaminobenzidine (DAB), denoted as TpDAB, BdDAB, and HbDAB, respectively. Benefiting from the hierarchical structure of the covalent organic polymer and synergistic effects originating from hydroxyl groups and imidazole linkages, TpDAB, BdDAB, and HbDAB displayed as the promising adsorbents for uranium extraction with high extraction ability and fast capture kinetics. X-ray photoelectron spectroscopy results revealed that both nitrogen atoms in imidazole and oxygen atom in hydroxyl took part in uranium coordination. With the increasing of hydroxyl group amounts, TpDAB achieved highest extraction capacity of uranium. Furthermore, TpDAB with imidazole affinity group possessed eminent selectivity for uranium in the multiple metal ions solution, and especiallyovercome the unavoidable problem of vanadium interfering with amidoxime adsorption uranium. This work provided a promising uranium extraction strategy with high selectivity and easy preparation for environmental protection and human health.
Dysregulated maternal nutrition, such as vitamin deficiencies and excessive levels of glucose and fatty acids, increases the risk for congenital heart disease (CHD) in the offspring. However, the ...association between maternal amino‐acid levels and CHD is unclear. Here, it is shown that increased leucine levels in maternal plasma during the first trimester are associated with elevated CHD risk in the offspring. High levels of maternal leucine increase embryonic lysine‐leucylation (K‐Leu), which is catalyzed by leucyl‐tRNA synthetase (LARS). LARS preferentially binds to and catalyzes K‐Leu modification of lysine 339 within T‐box transcription factor TBX5, whereas SIRT3 removes K‐Leu from TBX5. Reversible leucylation retains TBX5 in the cytoplasm and inhibits its transcriptional activity. Increasing embryonic K‐Leu levels in high‐leucine‐diet fed or Sirt3 knockout mice causes CHD in the offspring. Targeting K‐Leu using the leucine analogue leucinol can inhibit LARS activity, reverse TBX5 K‐Leu modification, and decrease the occurrence of CHD in high‐leucine‐diet fed mice. This study reveals that increased maternal leucine levels increases CHD risk in the offspring through inhibition of embryonic TBX5 signaling, indicating that leucylation exerts teratogenic effects during heart development and may be an intervening target of CHD.
Increased gestational leucine levels are significantly associated with risk for congenital heart disease (CHD) in offspring. Increased embryonic lysine‐leucylation (K‐Leu), generated via maternal high‐leucine‐chow feeding, or Sirt3 knockout, causes CHD in the offspring of mice, through elevating embryonic K‐Leu of TBX5 and inhibiting TBX5 activity. Targeting K‐Leu via leucinol reverses K‐Leu modifications and lowers the occurrence of CHD in mice.
•The farming technique of alternating small and large ridges with film mulching was introduced.•The technique significantly improved grain yield and water use efficiency of linseed flax.•Increased ...linseed productivity was explained by optimized water supply and thermal balance.•The technique substantially promoted economic profitability of dryland linseed production.
The farming practice of alternating ridges–furrows with plastic film mulching is widely used to improve field productivity of most staple crops such as maize and wheat in the semiarid Loess Plateau, but whether the technology has similar benefits on oil crops such as linseed flax (Linum usitatissimum L.), still remains unknown. From 2012–2013, a 2–year field experiment was carried out to evaluate the effects of different ridges–furrows mulching patterns on soil hydrothermal parameters, linseed yield performance, water use efficiency and economic benefit at a rainfed semiarid site of the Loess Plateau. Four different treatments were designed as: i) alternating small and large ridges with full film mulching (RFM), ii) alternating ridges and furrows with plastic film mulching only on the ridges (RM), iii) flat planting with fully film mulching (FM) and iv) conventional flat planting without mulching (CK). Local widely cultivated variety Tianya 9 was used as testing cultivar. The results indicated that soil water storage during early growing stage was increased by 7.1%, 0.6% and 6.3% in RFM, RM and FM, respectively, compared with that of CK across two growing seasons. After harvesting, soil water storage in RFM was recovered to higher level than that of CK. Average soil temperature at seedling stage was 3.1 °C and 2.1 °C higher in RFM and FM than that of CK. In addition, film mulching generally accelerated crop development during early vegetative period, leading to a shorter growing season in RFM and RM. Particularly, both linseed yield and water use efficiency were enhanced by 116.2% and 154.8% in RFM, 50.3% and 72.4% in RM, 87.5% and 84.2% in FM across two growing seasons, respectively, compared with those of CK. Critically, the greatest net income and output to input ratio were achieved in RFM across both growing seasons. Present results clearly suggest that the practice of alternating small and large ridges with full film mulching provide an innovative option to optimize soil hydrothermal conditions, thereby boosting the productivity and profitability of dryland linseed flax in rainfed semiarid environment.
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