Photochemical switching of the phase-transition temperatures of p-NIPAM-Pt nanoparticles thermosensitive polymer composites associated with electrodes: functional electrodes for switchable electrocatalysis

The thermosensitive poly(N-isopropylacrylamide) (p-NIPAM) is electropolymerized onto Au surfaces. The incorporation of the photoisomerizable N-carboxyethyl nitrospiropyran compound into p-NIPAM allows the reversible photochemical control of the gel-to-solid phase-transition temperatures of the polymer. Whereas the gel-to-solid phase-transition temperature of the nitrospiropyran-modified p-NIPAM is 33±2 °C, the phase-transition temperature of the nitromerocyanine-functionalized p-NIPAM matrix corresponds to 38±1 °C. Upon the incorporation of Pt nanoparticles (NPs) into the photochemically controlled p-NIPAM, a hybrid photoswitchable electrocatalytic matrix is formed. At a fixed temperature corresponding to 38 °C, the effective electrocatalytic reduction of H(2)O(2), or the oxidation of ascorbic acid, proceeded in the presence of the nitromerocyanine-functionalized p-NIPAM, yet these electrocatalytic transformations were inhibited in the presence of the nitrospiropyran-modified p-NIPAM.     

Determination of polyamines in human plasma by high‐performance liquid chromatography coupled with Q‐TOF mass spectrometry

A high‐performance liquid chromatography coupled with Q‐time of flight mass spectrometry (HPLC/Q‐TOF MS) method was developed and validated for the determination of 1, 3‐diaminopropane, putrescine, cadaverine, spermidine and spermine in human plasma. The plasma samples were first pretreated by 10% HClO₄ and then derived by benzoyl chloride with 1, 6‐diaminohexane as internal standard. The derived polyamines were separated on a C₁₈ column using a gradient program. The detection was performed on a Q‐TOF MS by positive ionization mode. Calibration curve for each polyamine was obtained in the concentration range of 0.4 ~ 200.0 ng ? ml^?1, with limit of detection of 0.02 ~ 0.1 ng ? ml^?1. The intra‐ and inter‐day RSD for all polyamines were 2.5–14.0% and 2.9 ~ 13.4%, respectively. The method was applied to determine the polyamines in human plasma from cancer patients and healthy volunteers. Results showed that the mean levels of polyamines in the plasma of cancer patients were higher than that of healthy volunteers, which suggested that the plasma polyamines could be employed as cancer diagnostic indicators in clinical testing. Copyright © 2012 John Wiley & Sons, Ltd.     

Highly flexible pseudocapacitor based on freestanding heterogeneous MnO2/conductive polymer nanowire arrays

Flexible electronics such as wearable electronic clothing, paper-like electronic devices, and flexible biomedical diagnostic devices are expected to be commercialized in the near future. Flexible energy storage will be needed to power these devices. Supercapacitor devices based on freestanding nanowire arrays are promising high power sources for these flexible electronics. Electrodes for these supercapacitor devices consisting of heterogeneous coaxial nanowires of poly (3,4-ethylenedioxythiophene) (PEDOT)-shell and MnO(2)-core materials have been shown in a half cell system to have improved capacitance and rate capabilities when compared to their pure nanomaterials; however, their performance in a full cell system has not been fully investigated. Herein, these coaxial nanowires are tested in both a symmetric and an asymmetric (utilizing a PEDOT nanowire anode) full cell configuration in the aspect of charge storage, charge rate, and flexibility without using any carbon additives and polymer binders. It is found that the asymmetric cell outperforms the symmetric cell in terms of energy density, rate capability, and cycle ability. The asymmetric device's electrode materials display an energy density of 9.8 Wh/kg even at a high power density of 850 W kg(-1). This device is highly flexible and shows fast charging and discharging while still maintaining 86% of its energy density even under a highly flexed state. The total device is shown to have a total capacitance of 0.26 F at a maximum voltage of 1.7 V, which is capable of providing enough energy to power small portable devices.     

Sesquiterpenes and other constituents from Dendranthema zawadskii var. latilobum

Six new germacranolides, zawadskinolides A-F (1-6), and a new eudesmane glucoside, chrysantiloboside (7) were isolated from the aerial parts of Dendranthema zawadskii var. latilobum, along with thirteen known constituents. Their structures were elucidated by means of spectroscopic evidence. Bioassay showed that flavonoids such as apigenin (9), (-)-eriodictyol (10) and nepetin (12), as well as the sesquiterpene lactone, zawadskinolide F (6), inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells with IC50 values of 66.15, 132.55, 35.44, and 91.32?μM, respectively.     

Three New Bisabolocurcumin Ethers from the Rhizomes of Curcuma longa L.

Three new bisabolocurcumin ethers, named demethoxybisabolocurcumin ether ( 1 ), bisabolocurcumin ether ( 2 ), and didemethoxybisabolocurcumin ether ( 3 ), along with two known compounds, 4 and 5 , were isolated from the AcOEt extract of the rhizomes of Curcuma longa L. Their structures were established by the analysis of NMR and MS data. The new compounds 1 – 3 , which possess a new 1,7‐diarylheptanoid skeleton linked with a bisabolone‐type sesquiterpene substructure by a C? O bond, were found for the first time in a natural source.     

BaGa2MQ6 (M = Si, Ge; Q = S, Se): a new series of promising IR nonlinear optical materials

The four compounds BaGa(2)MQ(6) (M = Si, Ge; Q = S, Se) have been identified as a new series of IR nonlinear optical (NLO) materials and are promising for practical applications. They are isostructural and crystallize in the noncentrosymmetric polar space group R3 of the trigonal system. Their three-dimensional framework is composed of corner-sharing (Ga/M)Q(4) (M = Si, Ge; Q = S, Se) tetrahedra with Ba(2+) cations in the cavities. The polar alignment of one (Ga/M)-Q2 bond for each (Ga/M)Q(4) tetrahedra along the c direction is conducive to generating a large NLO response, which was confirmed by powder second-harmonic generation (SHG) using a 2090 nm laser as fundamental wavelength. The SHG signal intensities of the two sulfides were close to that of AgGaS(2) and those for the two selenides were similar as that of AgGaSe(2). The large band gaps of 3.75(2) eV, 3.23(2) eV, 2.88(2) eV, and 2.22 (2) eV for BaGa(2)SiS(6), BaGa(2)GeS(6), BaGa(2)SiSe(6), and BaGa(2)GeSe(6), respectively, will be very helpful to increase the laser damage threshold. Moreover, all the four BaGa(2)MQ(6) (M = Si, Ge; Q = S, Se) compounds exhibit congruent-melting behavior, which indicates that bulk crystals needed for practical applications can be obtained by the Bridgman-Stockbarger method. The calculated birefringence indicates that these materials may be phase-matchable in the IR region and the calculated SHG coefficients agree with the experimental observations. According to our preliminary study, the BaGa(2)MQ(6) compounds represent a new series of promising IR nonlinear optical (NLO) materials which do not belong to the traditional chalcopyrite-type materials such as AgGaQ2 (Q = S, Se) and ZnGeP(2).     

One pot synthesis of heterometallic 3d-3d azido architectures: assembling strategy and magnetic properties

The Cu(II) ions usually have different coordinated geometry to other 3d ions, especially Ni(II) and Co(II) ions, in azido-carboxylate mixed ligand systems. That provides a potential way to synthesize rare heterometallic 3d-3d azido complexes with peculiar magnetic properties. Assembling Cu(II), M(II) (M = Ni and Co), azido and nicotinic acid in hydrothermal condition, two novel isomorphic 3D heterometallic 3d-3d azido complexes, [CuM(N(3))(2)(nicotinate)(2)](∞) (M = Ni(II) for 1 and Co(II) for 2) were obtained. The structure of the complexes can be described as EO azido and syn,syn carboxylate mixed bridged spin sequence chains (-1/2-J(1)-1-J(2)-1/2- for 1 and -1/2-J(1)-3/2-J(2)-1/2- for 2) linked by the pyridyl groups. Dominant ferromagnetic interactions were observed between the Cu(II) and M(II) ions in the chains despite the largest M-N-M angle of about 129° in the 3d metal azido-carboxylate mixed coordinated systems and weak antiferromagnetic interactions between the chains. At low temperature, a spin-flop phase transition was present in the Co(II) involved complex 2.     

Experimental investigations on the weakening effect of magnetic fields on surface‐enhanced Raman scattering

Currently, because of the wide use of magnetic/metal hybrid materials in the field of surface‐enhanced Raman scattering (SERS), magnetic fields (MFs) as a kind of surrounding environments of SERS substrates have been not ignored. And enormous attentions for the effect of MFs on SERS are very necessary. Our analysis from previous reports shows SERS signals are closely associated with MFs; yet the study of the exact effect of MFs on SERS is still in need of detail and broadening. In this work, we demonstrate that the use of Ni/Au microparticles (MPs) and Au hollow spheres (HSs) to study the effect of MFs on SERS signals. The experiments are preformed from three aspects, including the comparison of SERS signals of Ni/Au MPs with different Ms values, the comparison of SERS signals of Au HSs and Ni/Au MPs under different external MFs, and the comparison of SERS signals of single Au HS particle and single Ni/Au particle in the absence and presence of an external MF. Thereinto, under different external MFs from 0, 0.01, 0.02, 0.04 to 0.08 T, SERS signals of Au HSs and Ni/Au MPs are gradually weaker. According to the experiments, the weakening effect of MFs on SERS is confirmed. It is suggested that the weakening effect is originated from the blue‐shift of surface plasmon resonance and the locking of charge‐transfer from Au to probe molecules. Copyright © 2012 John Wiley & Sons, Ltd.