Latest ArticlesThe concentration of free zinc within insulin-storing vesicles is important for vesicle maturity and therefore requires accurate measurement. However, common small-molecule intensity-based probes and most available genetically encoded Förster resonance energy transfer (FRET)-based sensors for zinc are unsuitable for estimating the free zinc concentration in insulin-storing vesicles. Therefore, we have developed a novel FRET-based zinc sensor based on the RING motif of TRIM72, referred to as ZnT72R, which has an approximate Kd that varies from 6.07±0.28 μmol/L to 7.84±0.42 μmol/L in vitro and a cytosol-calibrated Kd of approximately 55.56±4.59 μmol/L in HEK293 T cells. To pinpoint the free zinc concentration of insulin-storing vesicles, we initially targeted ZnT72R to beta-cell vesicles by fusing them to NPY (neuropeptide Y). Following NPY-ZnT72R labeling, the FRET intensity ratios of vesicles were quantified. We found that the free zinc concentration in insulin-storing vesicles of diabetic db/db mice (28.30±1.33 μmol/L) was significantly lower than that of control mice (41.46±3.53 μmol/L).
Biomass-derived carbon materials have obtained great attention due to their sustainability, easy availability, low cost and environmentally benign. In this work, bamboo leaves derived nitrogen doped hierarchically porous carbon have been efficiently synthesized via an annealing approach, followed by an etching process in HF solution. Electrochemical measurements demonstrate that the unique porous structure, together with the inherent high nitrogen content, endow the as-derived carbon with excellent lithium/sodium storage performance. The porous carbon annealed at 700 ℃ presents outstanding rate capability and remarkable long-term stability as anodes for both lithium-ion batteries and sodium-ion batteries. The optimized carbon delivers a high discharge capacity of 450 mAh/g after 500 cycles at the current density of 0.2 A/g for LIBs, and a discharge capacity of 180 mAh/g after 300 cycles at the current density of 0.1 A/g for SIBs
This article describes a fast and simple electrochemical assay for detecting cell concentration. After cell death, the membrane of cells will be broken, and DNA molecules contained in the cells will be released, but this does not happen in living cells. Sodium molybdate can react with the phosphate backbone of the released DNA molecules to form phosphomolybdate precipitation and produces a corresponding redox current. The higher the concentration of DNA, the stronger the intensity of the current generated. Sodium molybdate solution and centrifuged cell supernatant were added onto the glassy carbon electrode to determine the cell concentration by measuring the current intensity. The cell viability, which means the ratio of living cells to the total cells, can also be determined by this method. This assay has the advantages of high sensitivity, low detection limit, and wide detection range. In addition, this method was successfully applied to the detection of cell concentration in human serum, which has potential clinical applications.
An organocatalytic asymmetric [3+2] cycloaddition of trifluoromethyl-containing azomethine ylides with cyclic 2, 4-dienones was developed. The process enables efficient incorporation of CF3 groups into functionalized spiro[pyrrolidin-3, 2'-oxindoles] in high yields with good to excellent enantio-and diastereoselectivities.
Nitrogen doping is a promising way to modulate the electrical properties of graphene to realize graphene-based electronics and promise fascinating properties and applications. Herein, we report a method to noncovalently assembly titanium(Ⅳ) bis(ammoniumlactato) dihydroxide (Ti complex) on nitrogen-doped graphene to create a reliable hybrids which can be used as a reversible chemical induced switching. As the adsorption and desorption of Ti complex in sequential treatments, the conductance of the nitrogen-doped graphene transistors was finely modulated. Control experiments with pristine graphene clearly demonstrated the important effort of the nitrogen in this chemical sensor. Under optimized conditions, nitrogen-doped graphene transistors open up new ways to develop multifunctional devices with high sensitivity.
A series of Tm3+/Dy3+ co-doped Ba3LaNa(PO4)3F (BLNPF) phosphors were synthesized successfully via a high-temperature solid-reaction, and luminescence properties were investigated. Upon near violet excitation, BLNPF:Tm3+, Dy3+ phosphors exhibit Tm3+:1D2-3F4 and Dy3+:4F9/2-6HJ (J = 15/2, 13/2, 11/2) transitions with different luminescence intensity. The emitting color of the obtained products was found to shift from blue to white as a result of efficient energy transfer (ET) from Tm3+ to Dy3+ ions. According to photoluminescence emission intensity, the positive effect of activator on ETefficiency was calculated and the maximum ET efficiency was found around 72.6% with Dy3+ concentration was 0.04. By means of Dexter's theoretical model, furthermore, dipole-dipole interaction was confirmed as the mechanism of energy transfer from Tm3+ to Dy3+ ions. The results suggested that BLNPF:Tm3+, Dy3+ phosphor might be a promising single-phased white-light-emitting phosphor for UV white-light LED.
As an emerging 2D conjugated material, graphitic carbon nitride (CN) has attracted great research attention as important catalytic medium for transforming solar energy. Nanostructure modulation of CN is an effective way to improve catalytic activities and has been extensively investigated, but remains challenging due to complex processes, time consuming or low yield. Here, taking advantage of recent discovered good solvents for CN, a nanoprecipitation approach using poor solvents is proposed for preparation of CN nanoparticles (CN NPs). With simple processes of CN dissolution and precipitation, we can quickly synthesize CN NPs (~40 nm) with a yield of up to 50%, the highest one to the best of our knowledge. As an example of potential applications, the as-prepared CN NPs were applied to photocatalytic degradation of dyes with an evident boosted performance up to 2.5 times. This work would open a new way for batch preparation of nanostructured CN and pave its large-scale industrial applications.
In this paper, we introduced a novel method to prepare the few-layer nitrogen-doped graphene (FNG) from expandable graphite with melamine. The super-capacitive properties of FNG were thoroughly characterized by a three-electrode system, and the results showed the FNG electrode achieved a specific capacitance as high as 83.8 mF/cm2 together with excellent cycling stability. This method could be a novel approach to combine the pseudo-capacitors and electric double layer capacitors.
Pore size and distribution in carbon-based materials are regarded to be a key factor to affect the electrochemical capacitive performances of the resultant electrodes. In this study, nitrogen and oxygen codoped porous carbons (NOPCs) are fabricated based on a simple Schiff-base reaction between m-phenylenediamine and terephthalaldehyde. The NOPCs have tunable morphologies, high surface areas, abundant heteroatom doping. More importantly, the carbons show a dominant micropores of 0.5-0.8 nm, comparable to the ionic sizes of LiTFSI (Li+ 0.069 nm; TFSI-0.79 nm) water-in-salt electrolyte with a high potential window of 2.2 V. Consequently, the fabricated symmetric supercapacitor gives a high energy output of 30.5 Wh/kg at 1 kW/kg, and high stability after successive 10, 000 cycles with ~96.8% retention. This study provides promising potential to develop high-energy supercapacitors.
Volume expansion and polysulfide shuttle effect are the main barriers for the commercialization of lithium-sulfur (Li-S) battery. In this work, we in-situ polymerized a cross-linked binder in sulfur cathode to solve the aforementioned problems using a facile method under mild conditions. Polycarbonate diol (PCDL), triethanolamine (TEA) and hexamethylene diisocyanate (HDI) were chosen as precursors to prepare the cross-linked binder. The in-situ polymerized binder (PTH) builds a strong network in sulfur cathode, which could restrain the volume expansion of sulfur. Moreover, by adopting functional groups of oxygen atoms and nitrogen atoms, the binder could effectively facilitate transportation of Li-ion and adsorb polysulfide chemically. The Li-S battery with bare sulfur and carbon/sulfur composite cathodes and cross-linked PTH binder displays much better electrochemical performance than that of the battery with PVDF. The PTH-bare S cathode with a mass loading of 5.97 mg/cm2 could deliver a capacity of 733.3 mAh/g at 0.2 C, and remained 585.5 mAh/g after 100 cycles. This in-situ polymerized binder is proved to be quite effective on restraining the volume expansion and suppressing polysulfide shuttle effect, then improving the electrochemical performance of Li-S battery.
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