Vacuum-deposited thin film porous ZnO-metal oxide hybrid systems for microsupercapacitor applications with Ir/IrO2in ZnO as a new, high-performance electrode.

We fabricate porous nanostructured 1µm thick ZnO-metal/metal oxide hybrid material thin films using a unique approach utilizing physical vapor deposition with postdeposition annealing. We study Pt, Pd, Ru, Ir and Sn as the metals and find they all form hybrid structures, however with differing physical and electrochemical properties. We investigate their applicability in microsupercapacitor electrodes in a LiCl aqueous electrolyte and find that the ZnO hybrid with Ir exhibits the highest capacitances. We follow with optimization and more detailed material studies of the ZnO-Ir hybrid showing that a significant amount of Ir is present in the material in the form of metallic Ir and indiffused Ir, while IrO2is also present in the nanoscale. We obtain electrodes with 5.25 mF · cm-2capacitance with 90% retention over 10 000 charge/discharge cycles in an aqueous LiCl electrolyte, which is better than the reported values for other Ir-based hybrids. Finally, we showed that the electrodes provide 2.64 mF · cm-2in a symmetric device with an operating voltage of 0.8 V. With this report, we discuss the influence of both Ir and IrO2on the capacitance, underlining the synergistic effect, and show them as promising inorganic matterials for integration with other supercapacitor electrodes.

Surface properties of SnO2 nanolayers prepared by spin-coating and thermal oxidation.

In this work, comparative studies of the surface morphology and surface chemistry of SnO2 nanolayers prepared by spin coating with subsequent thermal oxidation (SCTO) in the temperature range of 400-700 °C using scanning electron microscopy (SEM), atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) methods, are presented. The SEM images show that SCTO SnO2 nanolayers contain partly connected irregular structures strongly dependent on the final oxidation temperature, with interconnected single grains of longitudinal shape and size, resulting in a flatter surface morphology with respect to the commonly used three-dimensional (3D) SnO2 thin films. In turn, AFM studies additionally confirm that SCTO SnO2 nanolayers after post-oxidation annealing at higher temperatures contain isolated grains of average lateral dimensions in the range of 20-50 nm having a rather flat surface morphology of average surface roughness defined by the root mean square factor at the level of ∼2 nm. From the XPS experimental research it can be concluded that, for our SCTO SnO2 samples, a slight surface nonstoichiometry defined by the relative [O]/[Sn] concentration at the level of 1.8-1.9 is observed, also depending on the final post-oxidation temperature, being an evident contradiction to recently published literature using x-ray diffraction data. Moreover, XPS experiments show that there is also a permanent small amount of carbon contamination present at the surface of internal grains of our SCTO SnO2 nanolayers, creating an undesired potential barrier for interactions with gaseous species when they are used as the active materials for gas sensing devices.

Analysis of biosensor chips for identification of nucleic acids.

Two novel DNA-sequencing methods are described that use DNA hybridization biosensor chips. These two techniques involve either labeling the free nucleic acid with enriched stable isotopes or hybridizing DNA without labels to immobilized peptide nucleic acid (PNA) and detecting the phosphorus present in the DNA but not in the PNA. Sputter-initiated resonance ionization microprobe analysis was used to detect the presence of enriched tin isotope-labeled DNA and of phosphorus in natural DNA as a means to identify the presence of DNA after hybridization to oligodeoxynucleotides (ODNs) or PNAs, respectively, immobilized on a biosensor chip. The data clearly demonstrate that excellent discrimination between complementary and noncomplementary sequences can be obtained during hybridization of DNA to either ODNs or PNAs. The capability to detect different enriched stable isotope-labeled DNAs simultaneously allows high degrees of multiplexing which may be very advantageous for hybridization kinetics studies in complex systems, as well as significantly increasing the speed of analysis. Alternatively, by using natural DNA with PNA biosensor chips, discrimination for single-point mutation could be increased because of improved hybridization kinetics and direct analysis of genomic DNA may become possible without amplification. Both methods have the potential to provide a rapid method for DNA/RNA sequencing, diagnostics, and mapping.

Multiplexed DNA sequencing and diagnostics by hybridization with enriched stable isotope labels.

A new DNA diagnostic and sequencing system has been developed that uses time-of-flight resonance ionization mass spectrometry (TOF-RIMS) to provide a rapid method of analyzing stable isotope-labeled oligonucleotides in form 1 sequencing by hybridization (SBH). With form 1, the DNA is immobilized on a nylon membrane and enriched isotope-labeled individual oligonucleotide probes are free to seek out complementary DNAs during hybridization. The major advantage of this new approach is that multiple oligonucleotides can be labeled with different enriched isotopes and can all be simultaneously hybridized to the genosensor matrix. The probes can then be simultaneously detected with TOF-RIMS with high selectivity, sensitivity, and efficiency. By using isotopically enriched tin labels, up to 10 labeled oligonucleotides could be examined in a single hybridization to the DNA matrix. Greater numbers of labels are available if rare earth isotopes are employed. In the present study, matrices containing three different DNAs were prepared and simultaneously hybridized with two different probes under a variety of conditions. The results show that DNAs, immobilized on nylon surfaces, can be specifically hybridized to probes labeled with different enriched in isotopes. Discrimination between complementary and noncomplementary sites of better than 100 was obtained in multiplexed samples. This new SBH method, which employs stable isotopic labels to locate target DNAs and TOF-RIMS to detect the labels, will be a very versatile and extensive multiplexing method.

Comparison of the analysis of delta 9-tetrahydrocannabinol capsules by high-performance liquid chromatography and capillary gas chromatography.

The modification of a high-performance liquid chromatography (HPLC) system and the development of a capillary gas-chromatographic (GC) system for the analysis of delta 9-tetrahydrocannabinol, encapsulated in soft gelatin capsules, are described. A photodiode array detector was used to evaluate peak homogeneity after each HPLC system modification. Sesame oil was separated from the extract by Sep-Pak filtration prior to GC analysis. Quantitation by both systems had r values greater than 0.999 and R.S.D. values less than 1.0%. Simultaneous capsule assays by both methods agreed within 1%.

Effects of brief and intermediate exposures to sulfate submicron aerosols and sulfate injections and cardiopulmonary function of dogs and tracheal mucous velocity of sheep.

Pulmonary mechanics of anesthetized dogs were not changed or were minimally altered by breathing the following compounds as submicron aerosols in concentrations up to 17.3 mg/m3 for 7.5 min: (1) sodium chloride (as a control), (2) sodium sulfate, (3) ammonium sulfate, (4) zinc sulfate, (5) zinc ammonium sulfate, (6) ammonium bisulfate, (7) aluminum sulfate, (8) manganese sulfate, (9) nickel sulfate, (10) copper sulfate, (11) ferrous sulfate, and (12) ferric sulfate. Submicron aerosols of these compounds in concentrations of 4.1-8.8 mg/m3, administered for 4 h to anesthetized dogs, did not affect mechanics of breathing, hemodynamics, and arterial blood gases. In conscious sheep, tracheal mucous velocity was not altered by exposure to the submicron aerosols of the sulfate compounds. None of these compounds, injected iv in a dose of 1 mg, had adverse effects on mechanics of breathing, pulmonary and systemic hemodynamics, or arterial blood gases. In 100-mg injections, zinc sulfate and zinc ammonium sulfate produced a fall in cardiac output, systemic hypotension, hypoxemia, and metabolic acidosis. Copper sulfate at this dose produced pulmonary hypertension, a fall in cardiac output, hypoxemia, respiratory acidosis, and a decrease of specific total respiratory conductance. It is concluded that submicron aerosols of sulfate salts do not have adverse cardiopulmonary effects when administered in high concentrations for up to 4 h. However, prolonged exposure to high concentrations of zinc sulfate, zinc ammonium sulfate, and copper sulfate aerosols should be carefully monitored because of the possibility that lower levels of these compounds in the bloodstream for long time period might have adverse cardiopulmonary effects.

Effects of sulfuric acid aerosol on cardiopulmonary function of dogs, sheep, and humans.

Submicronic aerosol of sulfuric acid (H2SO4) originates from the burning of fossil fuels and discharge of vapor from the automobile engine equipped with the catalytic converter. This study was conducted to determine whether brief exposure to this aerosol in high concentrations adversely affects the cardiopulmonary system. In all studies, submicronic aerosol of sodium chloride was used as a control. Anesthetized dogs that breathed H2SO4 aerosol in concentrations up to 8 mg per m3 showed no effects on respiratory resistance, static lung compliance, and functional residual capacity. A 4-hour exposure to H2SO4 aerosol (4 mg per m3) produced no significant changes in mechanics of breathing, functional residual capacity, pulmonary and systemic arterial blood pressures, cardiac output, heart rate, and arterial blood gas tensions. Conscious sheep that breathed H2SO4 aerosol in concentrations up to 14 mg per m3 for 20 min had no alteration of tracheal mucous velocity in an immediate 3-hour follow-up period or 5 to 10 days later. Conscious sheep that breathed H2SO4 aerosol (4 mg per m3) for 4 hours had no significant alteration of tracheal mucous velocity immediately and 2 hours thereafter. Both normal and asthmatic adults breathing H2SO4 aerosol in concentrations up to 1 mg per m3 for 10 min showed no significant alteration of lung volumes, distribution of ventilation, ear oximetry, dynamic mechanics of breathing, oscillation mechanics of the chest-lung system, pulmonary capillary blood flow, diffusing capacity, O2 consumption, and pulmonary tissue volume. No delayed effects in pulmonary function nor exacerbation of bronchial asthma were observe during a follow-up period of a few weeks. The present study indicates that single exposure to submicronic H2SO4 aerosol does not produce an immediate or a delayed adverse effect on cardiopulmonary function in anesthetized dogs, conscious sheep, and normal and asthmatic adults.