A novel fluorescent sensor based on g-C3N4 nanofibers for the sensitive detection of dopamine (DA) has been proposed. We synthesized g-C3N4 nanofibers by directly hydrolyzing bulk g-C3N4 in the alkaline atmosphere (3 M NaOH). The obtained ultrathin g-C3N4 nanofibers were verified by characterizations of Transmission electronic microscope (TEM), X-ray diffractometer (XRD), Fourier transformation-infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). It was found that the fluorescence intensity of g-C3N4 nanofibers was obviously quenched by DA. Fluorescence resonance energy transfer (FRET) between DA and g-C3N4 nanofibers led to the fluorescence reduction of g-C3N4 nanofibers. The fluorescent probe based on g-C3N4 nanofibers exhibits linear responses to the concentration of DA in the range from 0 to 4 mu M and 4 to 20 mu M, the limit of detection is 17 nM. The fluorescent probe shows excellent stability, good selectivity with its application in serums. (C) 2019 Elsevier B.V. All rights reserved.
With a wide potential application in many different fields, superhydrophobic surfaces have attracted much attention, while their surface structure can be easily damaged by environmental and mechanical effects and thereby causes superhydrophobic performance failure. To solve these practical problems, a robust superhydrophobic coating was fabricated with modified epoxy resin and oleophilic alumina NPs. Prepared by layered preparation method and air spraing method, the coating had a contact angle of 157.57 degrees and a sliding angle of 2 degrees. In terms of mechanical durability, the coating retained superhydrophobic properties after 30 times of sandpaper rubbing or 45 times tape peeling, exhibiting a better mechanical wear resistance than that of the commercial coatings ("Never-wet"). In terms of chemical durability, the coating still has good superhydrophobic property after being immersed in an acid or base solution for 100 min. It is concluded that superhydrophobic surfaces prepared by the materials system own good mechanical robustness.
In this paper, we consider a family of one-generator quasi-cyclic (QC) codes and their applications in quantum codes construction. We give a sufficient condition for one-generator QC codes to be self-orthogonal with respect to the symplectic inner product. As the computational results, five new binary quantum codes with parameters [[45,29,5]], [[63,36,7]], [[73,55,5]], [[105,71,7]], and [[105,72,7]] improving the best-known lower bounds on minimum distance in Grassl's code tables are constructed.
In this paper, we consider a wide family of lambda-quasi-twisted (lambda-QT) codes of index 2 and provide a bound on the minimum Hamming distance. Moreover, we give a sufficient condition for dual containing with respect to Hermitian inner product of these involved codes. As an application, some good stabilizer quantum codes over small finite fields F-2 or F-3 are obtained from the class of lambda-QT codes.
Based on the research and development of remote sensing image target extraction technology, the deep learning framework of cascade principal component analysis network is used to study the sea surface vessel detection algorithm. The visible image of the sea surface vessel is the input, the suspected target area is determined by the significance test, the PVANet model is extracted from the suspected target area, and the result is input into the support vector machine to obtain the final classification result. The experimental results show that the designed algorithm can successfully output the results of the detection of the sea area in the airspace, and verify the efficiency and accuracy of the PVANet model by comparing with the CNN algorithm. It proves the superiority of the PVANet model in feature extraction.
An alternative strategy is proposed to achieve visible-blind ultraviolet (UV) monitoring. By introducing photochromic spiropyran (SP) molecules into the dielectric as the charge trapping layer, organic field-effect transistor (OFET) memories show a selective response to UV light and are inert to visible light. The photoisomerization of SP from the ring-close to ring-open states under UV illumination modifies its electronic structure, which facilitates electron trapping into the charge trapping layer and accordingly induces the memory effect. UV exposure recording can be realized by cumulative and nonvolatile electron trapping, enabling potential applications of OFET memories for UV monitoring in wearable electronics.
This study focused on characteristics of dissolved organic matter (DOM) in a vertical flow constructed wetland (VF CW) with a free water surface constructed wetland (FWS CW) in front using three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy. 3D-EEM fluorescence spectroscopy was employed to characterize the DOM samples along with the CW systems. Five main peaks could be identified from the 3D-EEM fluorescence spectra of the DOM samples in both CW systems. The fluorescence regional was divided into five parts and including five peaks using fluorescence regional integration method. The results indicated soluble microbial by-products (SMB) predominated in all the process and the DOM was mainly composed of SMB because of higher microbial activity and more microbial diversity in VF CW compared with FWS CW. We could conclude that VF CW had hardly removal ability of the humic acid-like. The hybrid CW systems had ability to remove the nonbiodegradable compounds and mostly owed to FWS CW.
This is the first report on an ecofriendly process for producing FAMEs and beta-farnesene via a two-stage bio-transformation of waste cooking oils (WCOs), in which the FAMEs are referred to as biodiesel products and beta-farnesene is used as a jet biofuel. First, the yield of FAMEs from untreated WCOs by Novozym 435 was 33% under the initial transesterification conditions with crude glycerol containing 46% (w/w) methanol. However, crude glycerol with highly concentrated methanol seriously inhibited fermentation for the production of beta-farnesene by an engineered E. coli strain with a relatively balanced mevalonate (MVA) pathway that was constructed with the recombinant plasmids pMevT, pMBIS and pFiI. The pretreatment of WCOs and optimization of the transesterification process were successfully performed to completely eliminate fermentation repression, and the methanol content in the crude glycerol was reduced to zero. The production of beta-farnesene (5.29 g/L) using this crude glycerol as a substrate was approximately 50% higher than that (3.56 g/L) produced under the initial conditions, which was more than 100% higher than that (2.62 g/L) produced using crude glycerol via chemical transesterification methods. Furthermore, the optimal transesterification process resulted in a sharply increased yield of FAMES (96%) compared that (33%) obtained under the initial conditions. Therefore, this biotechnology achieved a high FAMEs yield and beta-farnesene production and might be suitable for industrial-scale implementation.
A simple, novel electrochemical sensing platform based on porous g-C3N4 (PCN) and multi-walled carbon nanotubes (MWCNTs) for the sensitive detection of uric acid (UA) has been proposed. The obtained PCN possessed good biocompatibility and large specific surface area with good dispersion, which was beneficial to electrocatalysis. The introduction of MWCNT as the conducting matrix improved the poor conductivity of PCN. Due to synergistic effect, the redox peak currents of UA substantially enhanced at PCN/MWCNT-modified electrode. The oxidation peak current exhibited linear responses to the concentration of UA in the range from 0.2 to 4 mu M and 4 to 20 mu M, and the limit of detection was calculated as 0.139 mu M (signal-to-noise ratio of 3 (S/N = 3)). The sensor based on PCN/MWCNT-modified electrode was also successfully applied in human serums and also showed excellent selectivity, reproducibility, and stability. This work illustrated that the fabricated electrochemical sensor was promising for analytical applications. Graphical abstract
The peroxisome proliferator-activated receptor. (PPAR.) coactivator-1 alpha (PGC-1 alpha) was first identified in 1998 as a PGC-1 family member that regulates adaptive thermogenesis and mitochondrial function following cold exposure in brown adipose tissue. The PGC-1 family has drawn widespread attention over the past two decades as the energetic regulator. We recently summarized a review regarding PGC-1 signaling pathway and its mechanisms in cardiac metabolism. In this review, we elaborate upon the PGC-1 signaling network and highlight the recent progress of its versatile roles in cardiac diseases, including myocardial hypertrophy, peripartum and diabetic cardiomyopathy, and heart failure. The information reviewed here may be useful in future studies, which may increase the potential of this energetic regulator as a therapeutic target.
The function of Arctic soil ecosystems is crucially important for the global climate, and nitrogen (N) is the major limiting nutrient in these environments. This study assessed the effects of changes in nitrogen content on archaeal community diversity and composition in the Arctic lake area (London Island, Svalbard). A total of 16S rRNA genes were sequenced to investigate archaeal community composition. First, the soil samples and sediment samples were significantly different for the geochemical properties and archaeal community composition. Thaumarchaeota was an abundant phylum in the nine soil samples. Moreover, Euryarchaeota, Woesearchaeota, and Bathyarchaeota were significantly abundant phyla in the three sediment samples. Second, it was found that the surface runoff caused by the thawing of frozen soil and snow changed the geochemical properties of soils. Then, changes in geochemical properties affected the archaeal community composition in the soils. Moreover, a distance-based redundancy analysis revealed that NH4+-N (p < 0.05) and water content were the most significant factors that correlated with the archaeal community composition. Our study suggests that nitrogen content plays an important role in soil archaeal communities. Moreover, archaea play an important role in the carbon and nitrogen cycle in the Arctic lake area.
Low salinity is one of the most important abiotic factors that directly affect the abundance of the swimming crab, Portunus trituberculatus. Quantitative trait loci (QTL) mapping could be helpful in identifying the markers and genes involved in low salinity tolerance. In this study, two QTLs of low salt tolerance were mapped on linkage group 17 (LG17, 2.6-5.2 cM) based on a high-density linkage map. Ninety-five markers related to low salinity tolerance were identified via association analysis, and seventy-nine low salt-related candidate genes (including ammonium transport, aldehyde dehydrogenase, and glucosyltransferase) were screened from draft genome of the species via these markers. This represents the first report of QTL mapping for low salinity tolerance in the swimming crab, which may be useful to elucidate salinity adaptation mechanisms.
Electrochemical reduction of carbon dioxide (CO2) is an appealing approach toward tackling climate change associated with atmospheric CO2 emissions. This approach uses CO2 as the carbon feedstock to produce value-added chemicals, resulting in a carbon-neutral (or even carbon-negative) process for chemical production. Many efforts have been devoted to the development of CO2 electrolysis devices that can be operated at industrially relevant rates; however, limited progress has been made, especially for valuable C2+ products. Herein, a nanoporous copper CO2 reduction catalyst is synthesized and integrated into a microfluidic CO2 flow cell electrolyzer. The CO2 electrolyzer exhibits a current density of 653 mA cm(-2) with a C2+ product selectivity of approximate to 62% at an applied potential of -0.67 V (vs reversible hydrogen electrode). The highly porous electrode structure facilitates rapid gas transport across the electrode-electrolyte interface at high current densities. Further investigations on electrolyte effects reveal that the surface pH value is substantially different from the pH of bulk electrolyte, especially for nonbuffering near-neutral electrolytes when operating at high currents.
Nonprecious highly active electrocatalysts in water splitting are essential for large-scale storage of renewable hydrogen energy. Two dimensional (2D) layered double hydroxides (LDHs) are commonly regarded as promising electrocatalysts for oxygen evolution reaction (OER), while they are not so efficient for hydrogen evolution reaction (HER). Herein, we propose the NiCo LDHs derived NiCoPx with 2D mesoporous ultrathin nanoplates structure in-situ grown on carbon paper (NiCoPx/CP). The special nanostructure and rich active sites endow the binder-free NiCoPx/CP with excellent bifunctional electrocatalytic performance toward HER and OER with very low overpotentials of 56 mV for HER at 10 mA cm(-2) and 239 mV for OER at 30 mA cm(-2). Moreover, the NiCoPx/CP can be directly used as electrodes for both anode and cathode to construct an efficient alkaline water electrolyzer with a cell votage of 1.58 Vat 10 mA cm(-2), which show even better performance than that of the best known commercial Pt-C&RuO2/CP catalysts. This work presented here can offer a novel guidance for the construction of non-noble metal-based electrocatalysts with 2D nanostructure in energy applications.