The electrochem. detection of Hg in aq. solns. was studied at glassy C (GC) and In-Sn oxide (ITO) electrodes modified by Au nanoparticles (Au NPs). Two methods of modification were used: electrochem. redn. of HAuCl4 and electrostatic adsorption of Au NPs stabilized by citrate. We found that the Au NPs modified surfaces yielded higher sensitivity and sharper and more reproducible stripping peaks of Hg as compared with the bare electrodes. The effect of the modification by Au NPs on the stripping potential was examd. Interestingly, the stripping of Hg on GC and ITO modified by Au NPs occurred at the same potential as on bare GC and ITO, resp. Only the full coverage of ITO by either electrochem. deposited Au for a long time or by vapor deposition, shifted the stripping potential more pos. by \~0.4 V to that obsd. on a bare Au electrode. These and further expts. led us to conclude that the Au NPs served as nucleation sites for the deposition of Hg, whereas the GC or ITO are superior for the stripping of Hg. Hence, a combination of well-defined Au NPs on ITO or GC were found ideal for the electrochem. detection of Hg. We achieved a remarkable detection limit of 1 μm/L of Hg using an ITO surface modified by electrostatically adsorbed Au NPs. [on SciFinder(R)]

The electrochemical detection of mercury in aqueous solutions was studied at glassy carbon (GC) and indium-tin oxide (ITO) electrodes modified by gold nanoparticles (Au NPs). Two methods of modification were used: electrochemical reduction of HAuCl4 and electrostatic adsorption of Au NPs stabilized by citrate. We found that the Au NPs modified surfaces yielded higher sensitivity and sharper and more reproducible stripping peaks of Hg as compared with the bare electrodes. The effect of the modification by Au NPs on the stripping potential was examined. Interestingly, the stripping of Hg on GC and ITO modified by Au NPs occurred at the same potential as on bare GC and ITO, respectively. Only the full coverage of ITO by either electrochemically deposited Au for a long time or by vapor deposition, shifted the stripping potential more positive by ca. 0.4 V to that observed on a bare Au electrode. These and further experiments led us to conclude that the Au NPs served as nucleation sites for the deposition of Hg, whereas the GC or ITO are superior for the stripping of mercury. Hence, a combination of well-defined Au NPs on ITO or GC were found ideal for the electrochemical detection of Hg. Indeed, we achieved a remarkable detection limit of 1 μm·L(-1) of Hg using an ITO surface modified by electrostatically adsorbed Au NPs.[on SciFinder (R)]

The units of concn. of mercury noted as "μm L-1" should read as "ng L-1.". [on SciFinder(R)]

In this work we report the sensitive electroanalytical detection of uranium(VI) in aqueous solutions. Uranium commonly exists in aqueous solutions in the form of its oxo ion, uranyl (U(VI)O2(2+)). The detection of uranyl has been accomplished by us through its deposition upon reduction by two electrons to the insoluble UO2 using a bare disk gold macroelectrode and anodic stripping voltammetry (ASV). This gave an unsatisfactory detection limit of ca. 1 × 10(-5) M uranyl. Moreover, the evolution of hydrogen bubbles blocked the electrode surface as a result of water reduction at negative deposition potential (-0.7 V vs Ag/AgCl). The application of a 25 μm diameter Au microwire electrode on which UO2 precipitated at negative potential (-1.2 V) improved substantially the detection limit. Further improvement was accomplished by vibrating the microwire working electrode, which increased the amounts of UO2 deposition due to decreasing the diffusion layer. The effect of the vibrating amplitude and frequency on the electroanalytical response was studied and optimized. Eventually, a detection limit of ca. 1 × 10(-9) M uranyl was achieved using a 5 min deposition time, -1.2 V deposition potential, and vibrating the electrode at frequency of 250 Hz and amplitude of 6 V.[on SciFinder (R)]

The authors report the sensitive electroanal. detection of uranium(VI) in aq. solns. Uranium commonly exists in aq. solns. as its oxo ion, uranyl (UVIO22+). The detection of uranyl was accomplished by the authors through its deposition upon redn. by two electrons to the insol. UO2 using a bare disk gold macroelectrode and anodic stripping voltammetry (ASV). This gave an unsatisfactory detection limit of \~1 × 10-5 M uranyl. Also, the evolution of hydrogen bubbles blocked the electrode surface as a result of water redn. at neg. deposition potential (-0.7 V vs. Ag/AgCl). The application of a 25 μm diam. Au microwire electrode on which UO2 pptd. at neg. potential (-1.2 V) improved substantially the detection limit. Further improvement was accomplished by vibrating the microwire working electrode, which increased the amts. of UO2 deposition due to decreasing the diffusion layer. The effect of the vibrating amplitude and frequency on the electroanal. response was studied and optimized. Eventually, a detection limit of \~1 × 10-9 M uranyl was achieved using a 5 min deposition time, -1.2 V deposition potential, and vibrating the electrode at frequency of 250 Hz and amplitude of 6 V. [on SciFinder(R)]

An electrochemical insulin-delivery system based on reduced graphene oxide impregnated with insulin is described. Upon application of a potential pulse of -0.8 V for 30 min, up to 70 ± 4% of human insulin was released into a physiological medium while preserving its biological activity.[on SciFinder (R)]

An electrochem. insulin-delivery system based on reduced graphene oxide impregnated with insulin is described. Upon application of a potential pulse of -0.8 V for 30 min, up to 70 ± 4% of human insulin was released into a physiol. medium while preserving its biol. activity. [on SciFinder(R)]

A method of manufg. an electrochromic device is provided. The method includes providing a patterned arrangement of an elec. conductive material; and applying one or more layers of an electrochromic material to the patterned arrangement, wherein at least a portion of the electrochromic material is in elec. contact with the elec. conductive material. An electrochromic device and an electrochromic ink compn. are also provided. [on SciFinder(R)]

We report the fabrication of a new selective "inverse tandem" absorbing coating based on carbon nanotube (CNT)/indium-tin oxide (ITO) on aluminum (Al) for mid-temp. solar-thermal application. The CNT layer is formed by spraying and functions as an excellent solar absorber whereas the ITO layer produced on top of the CNTs by sputtering serves as an IR reflector. The effect of the thickness of the ITO on the spectral selectivity of the absorbing coating was investigated. Controlling the thickness of ITO allowed the spectral selectivity of the coating to be tuned. The CNT/ITO solar coatings with optimized thickness of ITO showed excellent spectral selectivity values of absorptance (α) of 0.927 and emittance (ε) of 0.2. The performance of the coatings at high temp. after heating in air in the range of 25-300°C for different durations was also investigated. The performance and structure of the CNT/ITO coating was also compared with the wet deposition method in which the ITO coating was formed by spraying. [on SciFinder(R)]

The electrochem. redn. of indium tin oxide (ITO) on glass is systematically studied. The light absorbance and elec. resistance of ITO increases upon redn. SEM images show that the integrate ITO films dissolve and form particles upon applying neg. potentials. The particles consist of metallic In and Sn, as characterized by XRD and XPS. The redn. of ITO strongly depends on the electrolyte conditions, mainly pH and anions. The onset potential is found to shift neg. as the pH of the electrolyte increases. NO-3 ions significantly inhibit the redn. of ITO, shifting the redn. potential neg. by \~500 mV as compared with SO2-4, Cl- and Br-. It can also serve as inhibitor by adding very low concn. to the Cl–dominant electrolyte. Also, the electrochem. reduced ITO show excellent nonlinear optical performance, with transmittance tuneable by redn. potential and time. This suggests a promising useful application of the electrochem. redn. of ITO. [on SciFinder(R)]

Layer-by-layer assembly method is employed to fabricate multilayer hybrid films based on poly(styrenesulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) and W oxide nanoparticles (WO3 NPs). Polyethylenimine (PEI) is deposited in between to introduce electrostatic force between the components. In the hybrid films, randomly oriented disk-like WO3 NPs are homogeneously distributed in the polymers and form an interdigitated structure. This very rough surface morphol. hinders the formation of a continuous PEI layer between the electrochromic layers. Owing to the efficient charge transfer between the two active components and complementary elec. cond. of the two components in the redox switching process, the coloration efficiency of the hybrid film is significantly improved to 117.7 cm2/C at wavelength of 633 nm. The underlying mechanism for the enhancement is verified by scanning electrochem. microscopic studies through probing the cond. changes of PEDOT:PSS, WO3-NP and hybrid films under various applied potentials. [on SciFinder(R)]

The use of printing to produce 2D arrays is well established, and should be relatively facile to adapt for the purpose of printing biomaterials; however, very few studies have been published using enzyme solutions as inks. Among the printing technologies, inkjet printing is highly suitable for printing biomaterials and specifically enzymes, as it offers many advantages. Formulation of the inkjet inks is relatively simple and can be adjusted to a variety of biomaterials, while providing nonharmful environment to the enzymes. Here we demonstrate the applicability of inkjet printing for patterning multiple enzymes in a predefined array in a very straightforward, noncontact method. Specifically, various arrays of the enzymes glucose oxidase (GOx), invertase (INV) and horseradish peroxidase (HP) were printed on aminated glass surfaces, followed by immobilization using glutardialdehyde after printing. Scanning electrochemical microscopy (SECM) was used for imaging the printed patterns and to ascertain the enzyme activity. The successful formation of 2D arrays consisting of enzymes was explored as a means of developing the first surface confined enzyme based logic gates. Principally, XOR and AND gates, each consisting of two enzymes as the Boolean operators, were assembled, and their operation was studied by SECM.[on SciFinder (R)]

The use of printing to produce 2D arrays is well established, and should be relatively facile to adapt for the purpose of printing biomaterials; however, very few studies have been published using enzyme solns. as inks. Among the printing technologies, inkjet printing is highly suitable for printing biomaterials and specifically enzymes, as it offers many advantages. Formulation of the inkjet inks is relatively simple and can be adjusted to a variety of biomaterials, while providing nonharmful environment to the enzymes. Here we demonstrate the applicability of inkjet printing for patterning multiple enzymes in a predefined array in a very straightforward, noncontact method. Specifically, various arrays of the enzymes glucose oxidase (GOx), invertase (INV) and horseradish peroxidase (HP) were printed on aminated glass surfaces, followed by immobilization using glutardialdehyde after printing. Scanning electrochem. microscopy (SECM) was used for imaging the printed patterns and to ascertain the enzyme activity. The successful formation of 2D arrays consisting of enzymes was explored as a means of developing the first surface confined enzyme based logic gates. Principally, XOR and AND gates, each consisting of two enzymes as the Boolean operators, were assembled, and their operation was studied by SECM. [on SciFinder(R)]