Preparation of fluorescent N,P-doped carbon dots derived from adenosine 5′-monophosphate for use in multicolor bioimaging of adenocarcinomic human alveolar basal epithelial cells

Carbon quantum dots doped with nitrogen and phosphorus were prepared from adenosine 5′-monophosphate (AMP) in a single simple synthesis step. The nitrogen and phosphorus doped C-dots (N,P-C-dots) were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy and X-ray powder diffraction. These carbon dots display blue fluorescence, with excitation/emission maxima at 360/430 nm, a quantum yield of 26.5% and an average decay time of 4.3 ns. Fluorescence is strongest at neutral pH values but quenched at very high and very low pH values. It is also quenched by ferric ions which suggests the use of the N,P-C-dots as fluorescent probes for Fe(III). A hemolysis test inferred favorable blood compatibility. The fluorescence of the doped C-dots is excitation wavelength dependent and also is susceptible to 2-photon excitation. The nanoparticles were applied in the fluorescent multicolor bioimaging of A549 (adenocarcinomic alveolar basal epithelial) cells under different excitation wavelengths, typically at 405, 488 and 543 nm. Emission colors ranging from blue to green and red can be adjusted in this way.

Open image in new window

Graphical abstract Nitrogen and phosphorus doped carbon dots were synthesized and showed excitation wavelength-dependent behavior. They were applied to multi-color fluorescence imaging of adenocarcinomic alveolar basal epithelial cells.

     

Linear ion trap with added octopole field component: the property and method

It is well known that superimposition of some positive octopole field will benefit the performance of ion trap mass analyzer. In the radial‐ejection linear ion trap (LIT), adding some octopole field component to the main quadrupole field is usually accomplished by stretching the ejection rod pair. In this study, the effect of octopole potential and some other higher order potential on the performance of LIT mass analyzer is investigated. A simple and effective method, which is to add some octopole component by building a LIT with a pair of rectangular electrodes and a pair of semi‐circular electrodes, is reported. Its properties were studied by numerical simulations and experiments. The results showed that a certain amount of positive octopole component could be produced by simply adjusting the position and width of the rectangular electrodes. A resolution of over 1200 at m/z 609 (~1600 Da/s) was observed in this type of LIT. They also performed tandem mass spectrometry well. The device with optimum geometry for ion ejection from rectangular electrodes provided comparable performance to that for ion ejection from semi‐circular electrodes. This type of LIT design is easy for fabrication and assembly. Copyright © 2015 John Wiley & Sons, Ltd.     

Ein μ2-Benzylidenkomplex des Chroms mit ungepaarten Elektronen

The benzylidene-bridged dichromium complex [CpCr]₂(μ-Br)₂(μ-CHC₆H₅) (4) has been obtained by thermolysis of [CpCr(CH₂C₆H₅)]₂(μ-Br)₂. ¹H NMR spectroscopy shows that 4 is antiferromagnetic and a barrier of 64.0 kJ mol⁻¹ slows down the rotation of the phenyl group.     

The full solution of the independent oscillator model and the properties of the environment

By using Laplace transformation, a set of analytic solutions of the coordinates and velocities for a system plus an environment are given. In the absence of system potential, based on the solutions, we rigorously prove that if the initial state of the composite system lies in its thermal equilibrium, then the environment is equipartition of energy, which, however, is moving with the system. At the same time, we discuss the time development of the mean square displacements, square velocities and the mean energies of both the system and the environment when the initial state is in partial thermal equilibrium or far away from thermal equilibrium. In addition, we also pay attention to the environmental behaviour when the initial state is deterministic. It is shown that the properties of the environment are quite different from those of the collection of oscillators discussed by Ford et al. (G.W. Ford, M. Kac and P Mazur, J. Math. Phys. 6 (1965) 504).     

Component reconstitution-driven photoelectrochemical sensor for sensitive detection of Cu2+ based on advanced CuS/CdS p-n junction

Science China Chemistry - The rational design of robust photoactive material and artful sensing strategy are vital for the construction of an ultrasensitive photoelectrochemical (PEC) sensor....     

A Yolk–Shell-Structured FePO4 Cathode for High-Rate and Long-Cycling Sodium-Ion Batteries

Amorphous iron phosphate (FePO₄) has attracted enormous attention as a promising cathode material for sodium-ion batteries (SIBs) because of its high theoretical specific capacity and superior electrochemical reversibility. Nevertheless, the low rate performance and rapid capacity decline seriously hamper its implementation in SIBs. Herein, we demonstrate a sagacious multi-step templating approach to skillfully craft amorphous FePO₄ yolk–shell nanospheres with mesoporous nanoyolks supported inside the robust porous outer nanoshells. Their unique architecture and large surface area enable these amorphous FePO₄ yolk–shell nanospheres to manifest remarkable sodium storage properties with high reversible capacity, outstanding rate performance, and ultralong cycle life.     

NBO电荷计算对电中性原理的检验

我们在B3LYP/6-31++G（d，p）计算级别下计算了[M（H₂O）₆]³⁺（M=Sc~Co）、[Co（Ⅲ）L₆]（L=F^-、H₂O、NH₃、CN^-），以及基于α-Al₂O₃晶体结构搭建的铝氧簇Al₃O（OH）₇（H₂O）₅（Al₃）和Al₆O₆（OH）₆（H₂O）₅（Al₆）的NBO电荷。除[Co（NH₃）₆]³⁺外，其它化合物均不符合经典教科书中的电中性原理，具有超出-1~+1范围的电荷。此外，我们发现中心原子的电荷受到配位原子种类的极大影响，而这一规律未在电中性原理的表述中。计算结果表明，从[CoF₆]^3-到[Co（CN）₆]^3-，中心离子上所带电荷量从+1.639变化至-1.360，且中心离子上所带电荷随其离子势的增大而降低。另外基于对铝氧簇的计算，我们预测α-Al₂O₃中的Al原子所带电荷应为2.1±0.1。     

Hybrid Transition-Metal Oxide and Nitride@N-Doped Reduced Graphene Oxide Electrodes for High-Performance,Flexible, and All-Solid-State Supercapacitors

Nanoscale composites for high-performance electrodes employed in flexible, all-solid-state supercapacitors are being developed. A series of binder-free composites, each consisting of a transition bimetal oxide, a metal oxide, and a metal nitride grown on N-doped reduced graphene oxide (rGO)-wrapped nickel foam are obtained by using a universal strategy. Three different transition metals, Co, Mo, and Fe, are separately compounded with nickel ions, which originate from the nickel foam, to form three composites, NiCoO₂@Co₃O₄@Co₂N, NiMoO₄@MoO₃@Mo₂N, and NiFe₂O₄@Fe₃O₄@Fe₂N, respectively. These as-prepared active materials have similar regular variation patterns in their properties, including better conductivity and battery-mimicking pseudocapacitance, which result in their high whole-electrode capacitance performance [2598.3 F g⁻¹ (39.85 F cm⁻²), 3472.6 F g⁻¹ (41.43 F cm⁻²) and 1907.5 F g⁻¹ (3.41 F cm⁻²) for the composites incorporating Co, Mo, and Fe, respectively]. The as-assembled flexible, all-solid-state NiCoO₂@Co₃O₄@Co₂N//KOH/PVA//NiCoO₂@Co₃O₄@Co₂N device can be easily bent and exhibits high energy density and power density of 92.8 Wh kg⁻¹ and 1670.4 W kg⁻¹, respectively. The universality of this design strategy could allow it to be employed in producing hybrid materials for high-performance energy-storage devices.     

Rapid Aqueous Synthesis of Large-Size and Edge/Defect-Rich Porous Pd and Pd-Alloyed Nanomesh for Electrocatalytic Ethanol Oxidation

In this work, a facile aqueous synthesis strategy was used (complete in 5 min at room temperature) to produce large-size Pd, PdCu, and PdPtCu nanomeshes without additional organic ligands or solvent and the volume restriction of reaction solution. The obtained metallic nanomeshes possess graphene-like morphology and a large size of dozens of microns. Abundant edges (coordinatively unsaturated sites, steps, and corners), defects (twins), and mesopores are seen in the metallic ultrathin structures. The formation mechanism for porous Pd nanomeshes disclosed that they undergo oriented attachment growth along the ⟨111⟩ direction. Owing to structural and compositional advantages, PdCu porous nanomeshes with certain elemental ratios (e. g., Pd₈₇Cu₁₃) presented enhanced electrocatalytic performance (larger mass activity, better CO tolerance and stability) toward ethanol oxidation.     

A boronate-modified renewable nanointerface for ultrasensitive electrochemical assay of cellulase activity

The saccharification of cellulosic biomass to produce biofuels and chemicals is one of the most promising industries for green-power production and sustainable development. Cellulase is the core component in the saccharification process. Simple and efficient assay method to determine cellulase activity in saccharification is thus highly required. In this work, a boronate-affinity surface based renewable and ultrasensitive electrochemical sensor for cellulase activity determination has been fabricated. Through boronate-sugar interaction, celluloses are attached to the electrode surface, forming the cellulose nano-network at the sensing interface. Cellulase degradation can lead to the variation of electrochemical impedance. Thus, electrochemical impedance signal can reflect the cellulase activity. Importantly, via fully utilizing the boronate-affinity chemistry that enables reversible fabrication of cellulose nano-network, a renewable sensing surface has been firstly constructed for cellulase activity assay. Thanks to interfacial diffusion process of electrochemical sensor, the product inhibitory effect in the cellulase activity assays can be circumvented. The proposed electrochemical sensor is ultrasensitive for label-free cellulase activity detection with a very simple fabrication process, showing great potential for activity screen of new enzymes in saccharification conversion.