Simulation and thermoeconomic analysis of different configurations of gas turbine (GT)-based dual-purpose power and desalination plants (DPPDP) and hybrid plants (HP)

This paper contains a simulation and a thermoeconomic analysis of several configurations of gas turbine (GT)-based dual-purpose power and desalination plants (DPPDP): Gas turbine with reverse osmosis (GT+RO), combined cycle with reverse osmosis (CC+RO), combined cycle with multi-effect distillation (CC+MED) and two different hybrid plant (HP) arrangements combining CC, MED and RO (CC+MED+RO, CC+MED+RO_bis). The last two configurations only differ from the feed solution to the MED units (raw seawater or brine coming from the RO discharge). A complete thermodynamic simulation at both design and at part load conditions has been made, as well as an exergy and an exergo-economic (thermoeconomic) analysis of each configuration, in order to compare the evolution of the water and electricity cost for different arrangements. The results show that even for a significantly reduced fuel cost (1.42 $/GJ), the CC is much more profitable than a GT operating in open cycle, with electricity cost values of 1.647 and 2.166 c$/kWh, respectively. As was expected, RO is more efficient and profitable than MED desalination processes, the difference in the obtained desalted water cost being significant. In the hybrid configuration with MED fed by the RO brine discharge, a decrease in the equivalent electrical consumption of nearly 2 kWh/m³ was achieved, but even in this case RO was more efficient (14.15 vs. 4.048 kWh/m³). The evolution of electricity cost in each configuration is more similar at part load operation than at full load, but in the case of water cost, RO is once again more profitable and less sensitive to load variations. Costs given in this paper correspond to investment and fuel costs. Further, profitability and operation strategies of HP, i.e., DPPDP combining distillation and membrane processes, are also analyzed. It is shown that HP can be more profitable than RO plants in the case of increasing the water production capacity of existing DPPDP, because the profit margin of HP remains positive within a substantial range for fuel price and investment costs. The operation strategies of HP were also studied in detail (by means of linear optimization) in order to minimize production costs; and it was concluded that electricity cost minimization gives the same result as the minimization of whole production cost; and water cost minimization could give a lower water cost than in the previous cases, but could lead to prohibitive electricity cost.     

Real-Time Electrochemical PCR with a DNA Intercalating Redox Probe

The proof-of-principle of a nonoptical real-time PCR method based on the electrochemical monitoring of a DNA intercalating redox probe that becomes considerably less easily electrochemically detectable once intercalated to the amplified double-stranded DNA is demonstrated. This has been made possible thanks to the finding of a redox intercalator that (i) strongly and specifically binds to the amplified double-stranded DNA, (ii) does not significantly inhibit PCR, (iii) is chemically stable under PCR cycling, and (iv) is sensitively detected by square wave voltammetry during PCR cycling. Among the different DNA intercalating redox probes that we have investigated, namely, methylene blue, Os[(bpy)(2)phen](2+), Os[(bpy)(2)DPPZ](2+), Os[(4,4'-dimethyl-bpy)(2)DPPZ](2+) and Os[(4,4'-diamino-bpy)(2)DPPZ](2+) (with bpy = 2,2'-bipyridine, phen = phenanthroline, and DPPZ = dipyrido[3,2-a:2',3'-c]phenazine), the one and only compound with which it has been possible to demonstrate the proof-of-concept is the Os[(bpy)(2)DPPZ](2+). In terms of analytical performances, the methodology described here compares well with optical-based real-time PCRs, offering finally the same advantages than the popular and routinely used SYBR Green-based real-time fluorescent PCR, but with the additional incomes of being potentially much cheaper and easier to integrate in a hand-held miniaturized device.     

Temperature coefficient of the high-frequency guided acoustic mode in a photonic crystal fiber

High-frequency guided acoustic Brillouin modes have recently been observed in small-core silica photonic crystal fibers. In this paper, we investigate the temperature dependence of the optical sideband frequency generated by one of these guided acoustic waves. The experimental results show a temperature coefficient of 100 kHz/°C at an acoustic resonance frequency of 1.15 GHz and are in very good agreement with the theoretical predictions. This coefficient demonstrates a temperature sensitivity 10 times larger than that previously reported in conventional single-mode fibers, which is promising in view of potential applications to optical fiber sensors.     

Chiral Phosphoric Acid‐Catalyzed Enantioselective Three‐ Component Aza‐Diels–Alder Reactions of Aminopyrroles and Aminopyrazoles

A highly stereoselective three‐component Povarov reaction, catalyzed by (R)‐ and (S)‐BINOL hydrogen phosphate, was achieved for the first time with aminopyrroles and aminopyrazoles as 2‐azadiene precursors. A variety of aldehydes, enecarbamates, amino‐substituted azines participated in the reaction to afford the tetrahydropyrrolopyridines and tetrahydropyrazolopyridines in good yields with excellent diatereo‐ and enantioselectivities. A stereochemical model is proposed to account for the observed absolute stereochemistry.

     

Enhanced chemosensing of ammonia based on the novel molecular semiconductor-doped insulator (MSDI) heterojunctions

A series of new molecular semiconductor-doped insulator (MSDI) heterojunctions as conductimetric transducers to NH₃ sensing were fabricated based on a novel semiconducting molecular material, an amphiphilic tris(phthalocyaninato) rare earth triple-decker complex, Eu₂[Pc(15C5)₄]₂[Pc(OC₁₀H₂₁)₈], quasi-Langmuir-Shäfer (QLS) film, as a top-layer, and vacuum-deposited and cast film of CuPc as well as copper tetra-tert-butyl phthalocyanine (CuTTBPc) QLS film as a sub-layer, named as MSDIs 1, 2 and 3, respectively. MSDIs 1-3 and respective sub-layers prepared from three different methods were characterized by X-ray diffraction, electronic absorption spectra and current-voltage (I-V) measurements. Depending on the sub-layer film-forming method used, α-phase CuPc film structure, β-phase CuPc crystallites and H-type aggregates of CuTTBPc have been obtained, respectively. An increasing sensitivity to NH₃ at varied concentrations in the range of 15-800 ppm, follows the order MSDI 2 < MSDI 3 < MSDI 1, revealing the effect of sub-layer film structures on sensing performance of the MSDIs. In particular, the time-dependent current plot of the MSDI 1, with α-phase CuPc film as a sub-layer, clearly shows an excellent separation of the different ammonia concentration levels and nearly complete reversibility and reproducibility even at room temperature, which is unique among the phthalocyanine-based ammonia sensors thus far reported in the literature. This provides a general method to improve sensor response of organic heterojunctions by controlling and tuning the film structure of sub-layer with appropriate fabrication techniques. On the other hand, the enhanced sensitivity, stability and reproducible response of the MSDI 1 heterostructure in comparison with the respective single-layer films have also been obtained. A judicious combination of materials and molecular architectures has led to enhanced sensing properties of the MSDI 1, in which control at the molecular level can be achieved.     

Urinary metabolites of 4-n-nonylphenol in rainbow trout (Oncorhynchus mykiss).

Nonylphenol is present in surface water and aquatic sediments and because of its lipophilic characteristics shows a considerable potential to bioaccumulate in aquatic organisms. Nonylphenol inhibits testicular growth and induces vitellogenin synthesis in male rainbow trout. In order to better understand the effects of nonylphenol on fish and its impact in the aquatic environment, it is essential to elucidate the metabolic fate of this compound. A single oral dose (5 mg, 1850 KBq) of [3H]4-n-nonylphenol resulted in 1.1% and 3.0% of the ingested radioactivity eliminated in urine after 24 and 48 h, respectively. Four metabolites were separated by radio-HPLC and tentatively identified by mass spectrometry. Urinary metabolites likely resulted from the initial omega-oxidation of 4-n-nonylphenol to the putative 9-(4-hydroxyphenyl)-nonanoic acid which subsequent beta-oxidation led to 4-hydroxybenzoic acid as major metabolite. Intermediary metabolites, namely 3-(4-hydroxyphenyl) propionic acid and 3-(4-hydroxyphenyl)-2-propenoic acid confirmed the occurrence of this beta-oxidative pathway. Urinary metabolites identified in this study were quite different from biotransformation products previously described in bile of trout treated with 4-n-nonylphenol.     

A multi-instrumented polymer exchange membrane fuel cell: Observation of the in-plane non-homogeneities

A multi-instrumented single polymer exchange membrane fuel cell is tested. It allows measuring local current densities and the temperature field along the gas channels. It is built from transparent PMMA so that an additional observable is the location where liquid water appears in the channels. Some local and transient observations are presented. A result is that the temperature field is strongly correlated with the current density distribution and it is confirmed that both depend strongly on water management. Some local aging effects and the observation of internal currents in open circuit conditions are reported.