Polycrystalline fluorine-doped tin oxide as sensoring thin film in EGFET pH sensor

The Extended Gate Field Effect Transistor (EGFET) is a device composed of a conventional ion-sensitive electrode and a MOSFET device, which can be applied for the measurement of ion content in a solution. The EGFET is fabricated connecting the sensitive membrane to a commercial MOSFET. We investigated the use of fluorine-doped tin oxide films (FTO) as sensitive membrane to EGFET. The commercial FTO shows a low resistivity and a crystalline structure, both determined using conductivity set-up and X-ray diffraction experiments, respectively. So far, it has been known that an amorphous structure is desirable to obtain high sensitivity. Despite of the a crystalline structure, we have fabricated the FTO as EGFET for pH sensor and carried out experiments in order to obtain the response of the device inserted into solutions with pH values from 2 up to 12. In this range, we have quantified a sensitivity of 50 mV/pH, which may have large potential applications as pH and biosensors. In addition, both the film and the structure of the sensor are cheaper and easier to make than in common techniques.     

An integrated approach for validating micro mechanical systems based on simulation and test

Miniaturization of macroscopic mechanical systems enables the opening of new areas of application for micro technological systems. Because of technological restrictions, especially when applying miniaturized conventional manufacturing techniques, shape and material deviations cannot be scaled down in the same dimension like micro parts. Thus, the long-term objective is to ensure the functioning by appropriate design measures. In doing so, determination of the transfer behavior by modeling and simulation is required. This work presents two ways for ensuring the required properties of micro gears and describes how the results do correlate. The experimental way uses the radial composite inspection as it is used in the macroscopic world. The simulative way deploys a rolling simulation by utilization of finite element analysis. The virtual prototypes are originated on measured real test gears. When comparing experiment and simulation of the rolling behavior, in some short and long wave areas deviations can be recognized. These can be ascribed to the reduction from three to two dimensions when modeling. Other deviations might be based on inaccuracies when mounting into the test rig. In other areas quite good correlations of test and simulation could be ascertained.     

Renewable energy in a market-based economy: How to estimate its potential and choose the right incentives

A model to explain and predict market-driven investment in renewable energy capital is proposed. The model is suitable for application to the biomass, wind, solar and ocean-derived energy industries. It basically assumes that, given a set of prices and a specific technology, the marginal efficiency of capital invested in these industries only depends on the productivity of the project's site and on its energy transport distance. As suggested by traditional investment theory, the model supposes that only those projects offering marginal efficiencies of capital above the current available rate of interest would be implemented, thus demarcating a region in the productivity–energy transport distance space where all the economically viable projects should lie. By relating this region to the geographic space available for development, total potential investment can be deduced. By using cash flows defined in variable energy transport distance and mean wind speed, a case study for the Chilean wind energy industry is presented. The use of the model to analyse the effect of alternative support schemes for wind energy in Chile is briefly demonstrated. It is concluded that for increasing the area economically available for the development of new wind farms, a research and development support scheme aimed at reducing investment cost of wind turbines by 25% is equivalent to a 20% price subsidy on energy.     

Phenomenon of phase inversion in high impact polystyrene: Physico‐chemical,rheological and morphological study in the presence of chain transfer agent and using different tapered block copolymers as the precursor rubber

Different high impact polystyrenes were synthesized using styrene/butadiene copolymers (SB) with PS/PB composition: 30/70 and 20/80 as the precursor rubber, benzoyl peroxide (BPO) as the initiator, and ter‐dodecyl mercaptane (TDM) as the chain transfer agent. During the polymerization, several samples were taken and analyzed under different techniques to evaluate the phase inversion (PI) phenomenon. The PI was determined through transmission electron microscopy (TEM) and through dynamic oscillatory behavior, where the PI takes places when the relaxation process presents the lower value of activation energy. Finally, the Choi and Schowalter emulsion model was employed to elucidate the PI, and relevant information was revealed about the interfacial tension in the PI. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Solubility of Δ-tetrahydrocannabinol in supercritical carbon dioxide: Experiments and modeling

The solubility of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) in supercritical carbon dioxide has been determined at 315, 327, 334 and 345 K and in the pressure range from 13.2 to 25.1 MPa using an analytical method with a quasi-flow apparatus. Prior to performing these measurements, the method was validated by measuring anthracene solubilities and comparing these with literature values. The molar solubility for Δ⁹-THC ranged from 0.20 to 2.95 × 10⁻⁴. The data were correlated using the Peng-Robinson equation of state in combination with quadratic mixing rules. Deviations between calculated results and the experimental data ranged from 4.1 to 13.3% absolute average relative deviation (AARD).     

Tannins, phytic phosphorus, phytase activity in the seed of 12 sorghum grain hybrids (Sorghum bicolor (L) Moench)

In order to evaluate the variability in concentration of secondary metabolites among grains from different sorghum hybrids (Sorghum bicolor (L) Moench) and provide some information for rational use in animal feeds, grain samples were collected from 12 hybrids (Criollo 1, Criollo 27, Chaguaramas III, Chaguaramas VII, Cristiani Burkard H-8046-2, Guanipa 95, Himeca 101, Himeca 400, Pioneer 81-G67, Pioneer 83-G88, Pioneer 86-P42 y Tecsem 120) sowed on 2008 in the Turén municipality, Portuguesa State-Venezuela. Using standardized analytical methods, hybrids showed polyphenolics compounds contents (0.92 +/- 0.37% TaE), total (0.61 +/- 0.29% TaE) and condensed tannins (0.95 +/- 0.65% LeuE), phytic phosphorus (0.17 +/- 0.03%) and intrinsic phytase activity (12.3 +/- 6.74 U/kg) in the ranges described in the literature, with an important variation among hybrids that must be considered for their inclusion levels in the formulation of balanced feeds, as well as plant breeding programs.     

Selective Green Coupling of Alkynyltins and Allylic Halides to Trienynes via a Tandem Double Stille Reaction

The palladium‐catalyzed reaction of alkynyltin compounds with allylic chlorides leads to a 2:2 coupling to give trienynes by regio‐ and stereoselective formation of three new C C bonds. The reaction can be applied to different alkynyl and allylic fragments, providing a wide range of trienynes with different substitution patterns in very good yields. They can be prepared in a green way using recyclable polymeric tin alkynyls.