Mode specificity in the HCl + OH → Cl + H2O reaction: Polanyi's rules vs sudden vector projection model.

The dynamics and mode specificity of the HCl + OH → Cl + H2O reaction are investigated using a full-dimensional quantum dynamics method on an accurate global potential energy surface. It is shown that the vibrational excitation of the HCl reactant greatly enhances the reactivity while the OH vibrational excitation has little effect. The surprising HCl vibrational enhancement of this early barrier reaction contradicts a naive extension of Polanyi's rules, but can be explained by the sudden vector projection model, which attributes the promotional effect of the HCl vibration to its strong coupling with the reaction coordinate at the transition state.

Insights into the bond-selective reaction of Cl + HOD(n(OH)) → HCl + OD.

Bond-selective reaction dynamics of the title reaction is investigated using full-dimensional quantum dynamical (QD) and quasi-classical trajectory (QCT) methods on a newly constructed ab initio global potential energy surface. Both QD and QCT results indicate that excitation of the local OH vibration in the HOD reactant renders the reaction strongly bond selective, with the OD/OH branching ratio in quantitative agreement with the experiment. In addition, the reactivity is found to be greatly enhanced with the reactant vibrational excitation, thanks to the change of a direct rebound mechanism to a capture mechanism.

Effects of reactant rotational excitations on H2 + NH2 → H + NH3 reactivity.

Rotational mode specificity of the title reaction is examined using an initial state selected time-dependent wave packet method on an accurate ab initio based global potential energy surface. This penta-atomic reaction presents an ideal system to test several dynamical approximations, which might be useful for future quantum dynamics studies of polyatomic reactions, particularly with rotationally excited reactants. The first approximation involves a seven-dimensional (7D) model in which the two non-reactive N-H bonds are fixed at their equilibrium geometry.

Synthesis of Au/graphene oxide composites for selective and sensitive electrochemical detection of ascorbic acid.

In this work, we present a novel ascorbic acid (AA) sensor applied to the detection of AA in human sera and pharmaceuticals. A series of Au nanoparticles (NPs) and graphene oxide sheets (Au NP/GO) composites were successfully synthesized by reduction of gold (III) using sodium citrate. Then the Au NP/GO composites were used to construct nonenzymatic electrodes in practical AA measurement.

Upconversion luminescence enhancement of Yb(3+), Nd(3+) sensitized NaYF4 core-shell nanocrystals on Ag grating films.

Here, we report the wavelength-dependent and angle-dependent upconversion luminescence (UCL) enhancement of NaYF4:Yb(3+),Tm(3+)@NaYF4:Yb(3+),Nd(3+) core-shell nanocrystals (NCs) resulting from Ag grating structures, which provides a novel insight for improving UCL.

Highly improved upconversion luminescence in NaGd(WO₄)₂:Yb³⁺/Tm³⁺ inverse opal photonic crystals.

The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL.

Ultrasensitive non-enzymatic glucose sensor based on three-dimensional network of ZnO-CuO hierarchical nanocomposites by electrospinning.

Three-dimensional (3D) porous ZnO-CuO hierarchical nanocomposites (HNCs) nonenzymatic glucose electrodes with different thicknesses were fabricated by coelectrospinning and compared with 3D mixed ZnO/CuO nanowires (NWs) and pure CuO NWs electrodes. The structural characterization revealed that the ZnO-CuO HNCs were composed of the ZnO and CuO mixed NWs trunk (~200 nm), whose outer surface was attached with small CuO nanoparticles (NPs). Moreover, a good synergetic effect between CuO and ZnO was confirmed.

Dysprosium, holmium and erbium ions doped indium oxide nanotubes as photoanodes for dye sensitized solar cells and improved device performance.

In this work, rare earth (RE) ion RE(3+) (RE(3+)=Dy(3+), Ho(3+) and Er(3+)) doped and undoped In2O3 nanotubes are synthesized by the electrospinning method and the band gap of In2O3 is systemically controlled, depending on the order of doped elements. Dye-sensitized solar cells (DSSCs) based on In2O3:RE(3+) nanotubes are also fabricated, and significantly improved performance of In2O3-DSSC is observed due to the modulation of the band gap, larger recombination charge transfer resistance and longer electron lifetime.

Mode specificity in the HF + OH → F + H2O reaction.

Full-dimensional quantum dynamics and quasi-classical trajectory calculations are reported for the title reaction on a recently constructed ab initio based global potential energy surface. Strong mode specificity was found, consistent with the prediction of the sudden vector projection model. Specifically, the HF vibration strongly promotes the reaction while the OH vibration has little effect.

Unglycosylated recombinant human glutathione peroxidase 3 mutant from Escherichia coli is active as a monomer.

Glutathione peroxidase 3 (GPx3) is a glycosylated member of GPx family and can catalyze the reaction of different types of peroxides with GSH to form their corresponding alcohols in vitro. The active center of GPx3 is selenocysteine (Sec), which is incorporated into proteins by a specific mechanism. In this study, we prepared a recombinant human GPx3 (rhGPx3) mutant with all Cys changed to Ser from a Cys auxotrophic strain of E.

A novel upconversion, fluorescence resonance energy transfer biosensor (FRET) for sensitive detection of lead ions in human serum.

There has been great progress in the development of fluorescence biosensors based on quantum dots (QDs) for the detection of lead ions. However, most methods are detecting lead ions in aqueous solution rather than in human serum due to the influence of protein autofluorescence in serum excited by visible light. Thus, we developed a novel fluorescence resonance energy transfer (FRET) biosensor by choosing the upconversion NaYF4:Yb(3+)/Tm(3+) nanoparticles as the energy donor and the CdTe QDs as the energy acceptor for lead ion detection.

Modulation of upconversion white light emission in PMMA/NaYF(4):Yb(3+), Er(3+), Tm(3+) composite photonic crystals.

In recent years, spontaneous emission modulation of emitters in photonic crystals (PCs) has been widely reported. However, the modulation of PCs on upconversion (UC) white light emission has been rarely studied. In this Letter, triply doped PMMA/NaYF(4):Yb(3+), Er(3+), Tm(3+) composite photonic crystals were successfully fabricated and white light emission was obtained.

Self-assembly and modified luminescence properties of NaY(MoO₄)₂:Tb³⁺, Eu³⁺ inverse opals.

Three-dimensional (3D) inverse opal photonic crystals can not only modulate the emissions of the inserted emitters, they also have the advantage of a large surface to volume ratio, which permits their use in noninvasive fluorescence detection. In this work, novel NaY(MoO4)2:Eu(3+) and NaY(MoO4)2:Tb(3+), Eu(3+) inverse opals were synthesized using a polymethylmethacrylate (PMMA) template by the sol-gel method. It was observed that the photoluminescence (PL) intensity and spontaneous decay rates (SDRs) of the inverse opals were suppressed, in contrast to the corresponding ground reference (REF) samples, due to the modulation of the effective refractive index (n(eff)).

Nine-dimensional quantum dynamics study of the H₂ + NH₂ → H + NH₃ reaction: a rigorous test of the sudden vector projection model.

Reaction dynamics and mode specificity in the H2 + NH2 → H + NH3 reaction are investigated in full dimensionality on a recent ab initio based global potential energy surface. Integral cross sections from several low-lying vibrational states of both reagents have been calculated under the centrifugal sudden or J-shifting approximations, using an initial state selected time-dependent wave packet method. This nine-dimensional system provides an ideal proving ground to test our recently proposed Sudden Vector Projection (SVP) model.

Efficient energy transfer from inserted CdTe quantum dots to YVO₄:Eu³⁺ inverse opals: a novel strategy to improve and expand visible excitation of rare earth ions.

Rare earth (RE)-based phosphors demonstrate sharp emission lines, long lifetimes and high luminescence quantum yields; thus, they have been employed in various photoelectric devices, such as light-emitting diodes (LEDs) and solar spectral converters. However, their applications are largely confined by their narrow excitation bands and small absorption cross sections of 4f-4f transitions. In this paper, we demonstrate a novel strategy to improve and expand the visible excitation bands of Eu(3+) ions through the interface energy transfer (ET) from CdTe quantum dots (QDs) to YVO₄:Eu(3+) inverse opal photonic crystals (IOPCs).

Ag-SiO₂-Er₂O₃ nanocomposites: highly effective upconversion luminescence at high power excitation and high temperature.

Rare Earth (RE) activated upconversion phosphors (UCPs), have demonstrated significant application potentials in some front fields, including solar energy conversion and bio-application. However, some bottleneck problems should be overcame, such as the lower upconversion efficiency, narrower excitation band, concentration-quenching and temperature-quenching. To solve these problems, the Ag-SiO2-Er2O3 nanocomposites were fabricated, in which the upconversion luminescence (UCL) of Er2O3 was white broadband.

[Mammalian DNA methylation and its roles during the induced re-programming of somatic cells].

The technology of induced pluripotent stem cell (iPS) provides the possibility to reverse the terminal differentiated cells to pluripotent stem cells, and is therefore of great importance in both the theoretical research of stem cells and regenerative medicine. However, the efficiency of current induced reprogramming methods is extremely low, and the incomplete reprogramming often happens. It has been reported that some epigenetic memory of the somatic cells exists in these incomplete reprogrammed iPS cells, and DNA methylation, as a relative long-term and stable epigenetic modification, is one of the important factors that influence the efficiency of reprogramming and differentiative capacity of iPS cells.

NaYF4:Yb,Tm nanocrystals and TiO2 inverse opal composite films: a novel device for upconversion enhancement and solid-based sensing of avidin.

Upconversion luminescence (UCL) detection based on rare-earth doped upconversion nanocrystals (UCNCs) as probes has been proved to exhibit a large anti-Stokes shift, no autofluorescence from biological samples, and no photobleaching. However, it is still a challenge to achieve a stable, reproducible solid-based UCL biosensor because of ineffective UCL of the UCNCs. In this work, we fabricated TiO2 inverse opal photonic crystals (IOPCs)/NaYF4:Yb(3+),Tm(3+) (Er(3+)) UCNC composite films, which can tremendously improve the overall UCL of Tm(3+) as high as 43-fold.

Zinc oxide inverse opal electrodes modified by glucose oxidase for electrochemical and photoelectrochemical biosensor.

The ZnO inverse opal photonic crystals (IOPCs) were synthesized by the sol-gel method using the polymethylmethacrylate (PMMA) as a template. For glucose detection, glucose oxidase (GOD) was further immobilized on the inwall and surface of the IOPCs. The biosensing properties toward glucose of the Nafion/GOD/ZnO IOPCs modified FTO electrodes were carefully studied and the results indicated that the sensitivity of ZnO IOPCs modified electrode was 18 times than reference electrode due to the large surface area and uniform porous structure of ZnO IOPCs.

Intense near-infrared quantum cutting emissions in LaF3:Sm3+ nanocrystals.

In this letter, visible to near-infrared (NIR) quantum cutting (QC) luminescence of -20 nm LaF3:Sm3+ (0.2-1 mol%) nanocrystals (NCs) was first studied. A number of novel NIR QC emissions (850-2000 nm) were distinguished.

Effects of reactant rotation on the dynamics of the OH + CH4 → H2O + CH3 reaction: a six-dimensional study.

The dynamics of the hydrogen abstraction reaction between methane and hydroxyl radical is investigated using an initial state selected time-dependent wave packet method within a six-dimensional model. The ab initio calibrated global potential energy surface of Espinosa-García and Corchado was used. Integral cross sections from several low-lying rotational states of both reactants have been obtained using the centrifugal sudden and J-shifting approximations.

Temperature-dependent upconversion luminescence and dynamics of NaYF4:Yb3+/Er3+ nanocrystals: influence of particle size and crystalline phase.

Oleic acid-capped NaYF4:Yb(3+)/Er(3+) upconversion nanocrystals (UCNCs) with different sizes and crystalline phases were prepared, and their temperature-dependent upconversion luminescence (UCL) and dynamics were studied. It is interesting to observe that the temperature-dependent behavior of UCL for the β-phase (25 nm, 45 nm and bulk) and α-phase (<10 nm) UCNCs is quite different. The UCL intensity of Er(3+) ions of the β-phase NaYF4 demonstrates a maximum around 100 K, while the intensity of the α-phase quenches monotonously with elevated temperature (10-400 K).

Simplified microchip electrophoresis for rapid separation of urine proteins.

Background: Urine protein test has been widely used in clinics, but to determine the type of proteinuria is usually difficult due to technical limitations.

Methods: In the current study, a rapid and simple method to separate and determine urine proteins by a microchip electrophoresis (ME) system has been developed in which only 4 min are required.

Results: Optimal separation conditions have been established by using 15 s injection time at 500 and 1,500 V separation voltage in 75 mmol/l borate buffer containing 0.

Controllable chrominance and highly improved luminescent quantum yield of YV(1-x)P(x)O4: Tm, Dy, Eu inverse opal white light phosphors.

In this work, rare earth (RE) ions tri-doped YV(1-x)P(x)O(4): RE(3+) (RE = Tm, Dy, Eu) inverse opal photonic crystals (IOPCs) were fabricated by the PMMA template method, which demonstrated efficient white light emissions under ultraviolet excitation. It is significant to observe that the chrominance of the white light could be largely modulated by the photonic stop band of the IOPCs. And more, the photoluminescence quantum yield in the IOPCs was largely improved over the grinded reference (REF) because the undesired energy transfer (ET) process was effectively restrained.

Synthesis of graphene oxide based CuO nanoparticles composite electrode for highly enhanced nonenzymatic glucose detection.

CuO nanoparticles (NPs) based graphene oxide (CuO/GO) composites with different CuO NPs loading amount as well as pure CuO NPs with different hydrothermal temperatures were synthesized using a hydrothermal method. Transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman spectroscopy were employed to characterize the morphology and structures of our samples. The influence of hydrothermal temperature, GO sheet, and loading amount of CuO on particle size and structure of CuO was systemically investigated.