Yehia Badr

Abstract This report describes a polydimethylsiloxane (PDMS)-thymol/nitroprusside delivery composite sensor for direct monitoring of ammonium in environmental water samples. The sensor is based on a \{PDMS\} support that contains the Berthelot's reaction reagents. To prepare the PDMS–thymol/nitroprusside composite discs, thymol and nitroprusside have been encapsulated in the \{PDMS\} matrix, forming a reagent release support which significantly simplifies the analytical measurements, since it avoids the need to prepare derivatizing reagents and sample handling is reduced to the sampling step. When, the PDMS–thymol/nitroprusside composite was introduced in water samples spontaneous release of the chromophore and catalyst was produced, and the derivatization reaction took place to form the indothymol blue. Thus, qualitative analysis of NH4+ could be carried out by visual inspection, but also, it can be quantified by measuring the absorbance at 690 nm. These portable devices provided good sensitivity (LOD < 0.4 mg L− 1) and reproducibility (RSD < 10%) for the rapid detection of ammonium. The PDMS–NH4+ sensor has been successfully applied to determine ammonium in water samples and in the aqueous extracts of particulate matter \{PM10\} samples. Moreover, the reliability of the method for qualitative analysis has been demonstrated. Finally, the advantages of the PDMS–NH4+ sensor have been examined by comparing some analytical and complementary characteristics with the properties of well-established ammonium determination methods.

Two types of coeval acid-intermediate rocks with different petrological, geochemical and isotopic features have been discovered among volcanic rocks and surrounding synkinematic tonalite–trondhjemite–granodiorite (TTG) plutons of Late Archaean greenstone belts in the Karelian granite–greenstone terrane. Type-1 rocks comprise trondhjemites and sub-volcanic, occasionally volcanic dacite–rhyolite rocks. They are characterized by high Sr, low Y and \{HREE\} contents, high Sr/Y ratios, and strongly fractionated \{REE\} patterns with no significant positive or negative Eu anomaly. Initial ɛNd is positive, indicating a generation from juvenile source with little or no contribution of ancient continental crust. Type 2 is represented by diorite–granodiorites and calc-alkaline basalt–andesite–dacite–rhyolite (BADR) series. As compared to type 1, these rocks differ by their lower Sr, higher Y and \{HREE\} contents, lower Sr/Y ratios and less fractionated \{HREE\} patterns with negative Eu anomalies. Initial ɛNd varies from negative to positive values, thus indicating a variable contribution of sialic crust. Geochemistry of the two magmatic series suggests their formation in a convergent plate margin setting. The type-1 rocks resemble Phanerozoic adakites, which represent slab-derived melts contaminated by overlying mantle wedge. The type-2 rocks resemble \{BADR\} series, which were derived from a mantle wedge metasomatized by slab-derived fluids and melts, with subsequent variable crustal contamination. The spatial distribution of these two types of magmatic series defines the asymmetry of the studied granite–greenstone structures, which presumably reflects the primary lateral zoning of island arc formed under specific thermal conditions in the Archaean mantle. Adakite melts upraised to the surface in the frontal part of the island arc, where mantle wedge was thin, showing no or little interaction with metasomatized mantle, and formed adakite-type plutonic and sub-volcanic rocks. At greater depths, adakitic melts and fluids interacted with the overlying mantle wedge and caused its partial melting with generation of calc-alkaline \{BADR\} volcanic rocks and diorite–granodiorite plutons in the rear part of the island arc. Our data suggest that greenstone belt volcano-plutonic arcs were initiated on different types of crust, which presumably determined the petrogenetic and isotope variations of the studied BADR- and adakite-type island-arc complexes.

Abstract This paper presents a review of the optimization techniques and strategies applied to wind turbine performance optimization. The topic is addressed by identifying the most significant objectives, targets and issues, as well as the optimization formulations, schemes and models available in the published literature. The current energy demand combined with depletion of fossil-fuel reserves and stricter environmental regulations have led to the development of alternative renewable energy solutions like wind energy. The current 2030 United States target is to have at least 20% of the \{US\} energy supply by onshore and offshore wind farms. To meet these demands, wind energy costs have to be able to compete with traditional fossil fuel sources. Hence, it is essential and vital that wind turbine designers and manufactures search the optimal solution that fits the objectives under a set of design constraints. Throughout the last 30 years, the objective function has evolved from the earlier maximized metric of the power coefficient to the maximization of the annual energy production. Common alternatives such as blade mass minimization and maximization of the rotor thrust and torque have been examined. However, the main objective has been focused on the minimization of the cost of energy in order for wind energy to become more competitive and economically attractive. The purpose of this paper is to review previous work that undertakes the performance optimization of horizontal wind turbines by highlighting the main aspects when tackling the wind turbine optimization problem such as: objective functions, design constraints, tools and models and optimization algorithms. In addition, in a conclusion of the review, a discussion and argument about the challenges, issues and future developments are identified.