Bifunctional OER/NRR Catalysts Based on a Thin-Layered Co₃O_4–<i>x</i>/GO Sandwich Structure

Due to ample low-coordinated surface atoms, a distorted lattice endows thin-layered transition metal oxides with a flexible electronic structure, making them the ideal candidates for overall ammonia synthesis. This work proposes a novel and facile method for the controllable synthesis of thin-layered Co3O4 catalysts with graphene as a conductive matrix to further enhance the overall N2 fixation performance. X-ray photoelectron spectroscopy (XPS) and synchrotron radiation X-ray absorption spectroscopy (XAS) demonstrate that the sandwiched Co3O4–x/GO catalysts enable exposure of more coordination unsaturated active sites, resulting in numerous oxygen vacancies. With a higher conductivity and distorted crystalline structure, excellent electrochemical NRR activity is realized with a NH3 production rate of 5.19 mmol g–1 h–1 and a Faradaic efficiency of 10.68% at −0.4 V vs reversible hydrogen electrode (RHE). The density functional theory (DFT) calculation demonstrates that introducing oxygen vacancies in thin-layered cobalt oxides could result in an increased density of states (DOS) near the Fermi level, which would accelerate the NRR rate-determining step. Charge transfer could be accelerated through a weak Co 3d–N 2p σ hybrid bond with a lower energy level. No obvious performance decay could be found after six cycles. Furthermore, the sandwiched Co3O4–x/GO catalyst exhibits a low overpotential of 280 mV@10 mA cm–2 and an outstanding durability for the anode OER, even better than those of the benchmark RuO2. Such an inexpensive sandwiched transition metal oxide catalyst shows great potential in the field of overall N2 fixation

Low genetic diversity and lack of genetic structure in the giant jellyfish <i>Nemopilema nomurai</i> in Chinese coastal waters

<p>The giant jellyfish <i>Nemopilema nomurai</i> is a scyphozoan species well-known in East Asian Marginal Seas for its damage to fisheries. The genetic diversity and population structure of <i>N. nomurai</i>, collected from five geographic regions in Chinese coastal seas, were examined based on mitochondrial cytochrome <i>c</i> oxidase subunit I (COI) gene and nuclear internal transcribed spacer one (ITS1) sequences. A total of 26 and five unique haplotypes were recovered from the COI and ITS1 genes, respectively. The overall genetic diversity of <i>N. nomurai</i> calculated by the COI and ITS1 sequences was low (haplotype diversity 0.727% and 0.108%, nucleotide diversity 0.212% and 0.039%). The median-joining network analysis revealed a star-like haplotype network. The hierarchical Analysis of Molecular Variance (AMOVA) of COI haplotypes showed that <i>N. nomurai</i> populations form a single population, with a low F_ST (0.0149, <i>p</i> = 0.1036). The dispersal ability, together with the biological characteristics, could be important factors for the lack of a geographically structured pattern in <i>N. nomurai</i> in Chinese coastal waters.</p

Enhanced Photoresponse of SnSe-Nanocrystals-Decorated WS₂ Monolayer Phototransistor

Single-layer WS₂ has shown excellent photoresponse properties, but its promising applications in high-sensitivity photodetection suffer from the atomic-thickness-limited adsorption and band-gap-limited spectral selectivity. Here we have carried out investigations on WS₂ monolayer based phototransistors with and without decoration of SnSe nanocrystals (NCs) for comparison. Compared to the solely WS₂ monolayer, SnSe NCs decoration leads to not only huge enhancement of photoresponse in visible spectrum but also extension to near-infrared. Under excitation of visible light in a vacuum, the responsivity at zero gate bias can be enhanced by more than 45 times to ∼99 mA/W, and the response time is retained in millisecond level. Particularly, with extension of photoresponse to near-infrared (1064 nm), a responsivity of 6.6 mA/W can be still achieved. The excellent photoresponse from visible to near-infrared is considered to benefit from synergism of p-type SnSe NCs and n-type WS₂ monolayer, or in other words, the formed p-n heterojunctions between p-type SnSe NCs and n-type WS₂ monolayer

Changes in Lipid Profiles of Dried Clams (<i>Mactra chinensis Philippi</i> and <i>Ruditapes philippinarum</i>) during Accelerated Storage and Prediction of Shelf Life

To predict the shelf life through an Arrhenius model and evaluate the changes in lipid profiles, two types of dried clams were stored at 50 and 65 °C and collected periodically for analysis. The predicted shelf life values of the two dried clam samples were 530 ± 14 and 487 ± 24 h (24 °C), and the relative errors between the actual and predicted values were 5.7 and 6.8%, respectively. During accelerated storage, the peroxide value, <i>p</i>-anisidine value, thiobarbituric acid-reactive substances value, total oxidation value, acid value, and free fatty acid content all increased, while the levels of triacylglycerol, phosphatidyl­choline, phosphatidyl­ethanol­amine, major glycerophospholipid molecular species, and polyunsaturated fatty acid (PUFA) decreased. Moreover, content of phospholipid containing PUFA decreased significantly than that of triacylglycerol containing PUFA. Results indicated that the Arrhenius model was suitable for the shelf life prediction of dried clams and accelerated storage caused loss in quality of dried clams in terms of lipids

Ultrahigh-Gain and Fast Photodetectors Built on Atomically Thin Bilayer Tungsten Disulfide Grown by Chemical Vapor Deposition

The low responsivity observed in photodetectors based on monolayer transition-metal dichalcogenides has encouraged the pursuit of approaches that can efficiently enhance the external quantum efficiency, which relies predominantly on the light absorption, the lifetime of the excess carriers, and the charge collection efficiency. Here, we demonstrate that phototransistors fabricated on large-area bilayer tungsten disulfide (WS₂) grown by chemical vapor deposition exhibit remarkable performance with photoresponsivity, photogain, and detectivity of up to ∼3 × 10³ A/W, 1.4 × 10⁴, and ∼5 × 10¹² Jones, respectively. These figures of merit of bilayer WS₂ provide a significant advantage over monolayer WS₂ due to the greatly improved carrier mobility and significantly reduced contact resistance. The photoresponsivity of bilayer WS₂ phototransistor can be further improved to up to 1 × 10⁴ A/W upon biasing a gate voltage of 60 V, without evident reduction in detectivity. Moreover, the bilayer WS₂ phototransistor exhibits a high response speed of less than 100 μs, large bandwidth of 4 kHz, high cycling reliability of over 10⁵ cycles, and spatially homogeneous photoresponse. These outstanding figures of merit make WS₂ bilayer a highly promising candidate for the design of high-performance optoelectronics in the visible regime

Electrochemiluminescence Resonance Energy Transfer Based on Ru(phen)₃²⁺-Doped Silica Nanoparticles and Its Application in “Turn-on” Detection of Ozone

Both the electrochemiluminescence (ECL) method for sensitive detection of ozone and the ECL resonance energy transfer (ECRET) using ozone have been reported for the first time. It is based on the ECRET of Ru­(phen)₃²⁺-doped silica nanoparticles (RuSiNPs) to indigo carmine. In the absence of ozone, the ECL of RuSiNPs is quenched as a result of the ECRET of RuSiNPs to indigo carmine. In the presence of ozone, the ECL of the system is “turned on” because ozone can oxidize indigo carmine and interrupt the ECRET from RuSiNPs to indigo carmine. In this way, it provides a simple ECL sensing of ozone via the proposed RuSiNP-based ECRET strategy with a linear range from 0.05–3.0 μM and a limit of detection (LOD) of 30 nM. The detection takes less than 5 min. This method is also successfully applied in the analysis of ozone in human serum samples and atmospheric samples

Stainless Steel Electrode for Sensitive Luminol Electrochemiluminescent Detection of H₂O₂, Glucose, and Glucose Oxidase Activity

Electrogenerated chemiluminescence (ECL) application of stainless steel, a robust and cost-effective material, has been developed for the first time. Type 304 stainless steel electrode shows appealing ECL performance in the luminol–H₂O₂ system. It enables the detection of H₂O₂ with a linear range from 1 to 1000 nM and a limit of detection of 0.456 nM [signal-to-noise ratio (S/N) = 3]. The ECL method based on type 304 stainless steel electrode is more sensitive, more cost-effective, and much simpler than other ECL methods reported before. Because the stainless steel electrode has excellent performance for H₂O₂ detection and H₂O₂ participates in many important enzymatic reactions, applications of stainless steel electrode-based ECL for detection of enzyme activities and enzyme substrates were further investigated by use of glucose oxidase (GODx) and glucose as representative enzyme and substrate. The concentrations of glucose and the activity of GODx were directly proportional to ECL intensities over a range of 0.1–1000 μM and 0.001–0.7 units/mL with limits of detection of 0.076 μM and 0.00087 unit/mL (S/N = 3), respectively. This method was successfully used for determining glucose in honey. Because of their remarkable performance and user-friendly features, stainless steel electrodes hold great promise in various electroanalytical applications, such as biosensing, disposable sensors, and wearable sensors

Purification of the Rv0045c protein by ion exchange chromatography and gel filtration chromatography.

<p>The Rv0045c protein was purified by anion exchange chromatography (A), cation exchange chromatography (B), and gel filtration chromatography (C). The purity was checked by SDS-PAGE analysis after each purification procedure.</p

Electric-Field Control of Spin–Orbit Torques in WS₂/Permalloy Bilayers

Transition metal dichalcogenides (TMDs) have drawn great attention owing to their potential for electronic, optoelectronic, and spintronic applications. In TMDs/ferromagnetic bilayers, an efficient spin current can be generated by the TMDs to manipulate the magnetic moments in the ferromagnetic layer. In this work, we report on the electric-field modulation of spin–orbit torques (SOTs) in WS₂/NiFe bilayers by the spin-torque ferromagnetic resonance technique. It is found that the radio frequency current can induce a spin accumulation at the WS₂/NiFe interface because of the interfacial Rashba–Edelstein effect. As a consequence, the SOT ratio between the field-like and antidamping-like torques can be effectively controlled by applying the back-gate voltage in WS₂/NiFe bilayers. These results provide a strategy for controlling the SOT by using semiconducting TMDs

MALDI-TOF peptide mass fingerprint (PMF) spectrometry of the Rv0045c protein.

<p>The PMF analysis was made from fragments of purified Rv0045c protein derived through trypsin digestion. The expected tryptic masses clearly matched, with 1 Da tolerance, the calculated values. The sequence coverage of these fragments was shown in bold red.</p