Synthesis of new imines and amines containing organosilicon groups

The Peterson olefination reaction of terephthalaldehyde with tris(trimethylsilyl)methyl lithium, (Me₃Si)₃CLi, in THF at 0 °C gives 4-[2,2-bis(trimethylsilyl)ethenyl]benzaldehyde (1) and 4,4-bis[2,2-bis(trimethylsilyl)ethenyl]benzene (2). The new aldehyde (1) reacts with variety of amines in ethanol to afford the corresponding imines (3) containing vinylbis(trimethylsilyl) group. The newly synthesized imines (3) can be completely converted into amines containing vinylbis(trimethylsilyl) group with an excess amount of NaBH₄. In the case of N-[4-(2,2-bis(trimethylsilyl)ethenyl)benzyl]-2,6-dimethylaniline LiAlH₄ was used as a reducing agent in THF.     

Dinuclear copper complexes of pyridylphenylphosphine ligands: Characterization of a mixed-valence Cu/Cu dimer

Homo bi-copper complexes [Cu₂{PhP(2-py)₂}₂(NO₃)₃] (1) and [Cu₂{P(2-py)₃}₂Cl₂] (2), were synthesized from the reaction of Cu(NO₃)₂·3H₂O and CuCl₂·2H₂O with their corresponding 2-pyridylphosphine ligands. Compound 1 has a mixed valence Cu(I)-Cu(II) core with electron acceptor phosphine atoms and two NO₃⁻ anions coordinated in a monodentate fashion to Cu(I), giving it a distorted tetrahedral geometry. The environment of Cu(II) in 1 is composed of four nitrogen atoms from pyridyl and another NO₃⁻ anion in a square pyramidal geometry. This complex shows luminescence and a low energy absorption band at 969 nm corresponding to intermetallic electron transfer between the copper centers. Complex 2 was prepared from the treatment of copper(II) chloride with tris(2-pyridyl)phosphine, producing a binuclear copper complex which possesses a crystallographic inversion center. The copper geometry in this complex is distorted tetrahedral with coordination of one Cl⁻, two nitrogens from one bridging tris(2-pyridyl)phosphine ligand and one P atom from the other bridging tris(2-pyridyl)phosphine ligand, in a similar way observed in related complexes. The products have been characterized by spectroscopic methods and also by the single-crystal X-ray diffraction method.     

Metal matrix composites for sustainable lotus-effect surfaces

The lotus effect involving roughness-induced superhydrophobicity is a way to design nonwetting, self-cleaning, omniphobic, icephobic, and antifouling surfaces. However, such surfaces require micropatterning, which is extremely vulnerable to even small wear rates. This limits the applicability of the lotus effects to situations when wear is practically absent. To design sustainable superhydrophobic surfaces, we suggest using metal matrix composites (MMCs) with hydrophobic reinforcement in the bulk of the material, rather than only at its surface. Such surfaces, if properly designed, provide roughness and heterogeneity needed for superhydrophobicity. In addition, they are sustainable, since when the surface layer is deteriorated and removed due to wear, hydrophobic reinforcement and roughness remains. We present a model and experimental data on wetting of MMCs. We also conducted selected experiments with graphite-reinforced MMCs and showed that the contact angle can be determined from the model. In order to decouple the effects of reinforcement and roughness, the experiments were conducted for initially smooth and etched matrix and composite materials.     

Quantum chemical and theoretical kinetics study of the O(3P) + CS2 reaction

The triplet potential energy surface of the O((3)P) + CS(2) reaction is investigated by using various quantum chemical methods including CCSD(T), QCISD(T), CCSD, QCISD, G3B3, MPWB1K, BB1K, MP2, and B3LYP. The thermal rate coefficients for the formation of three major products, CS + SO ((3)Σ(-)), OCS + S ((3)P) and CO + S(2) ((3)Σ(-)(g)) were computed by using transition state and RRKM statistical rate theories over the temperature range of 200-2000 K. The computed k(SO + CS) by using high-level quantum chemical methods is in accordance with the available experimental data. The calculated rate coefficients for the formation of OCS + S ((3)P) and CO + S(2) ((3)Σ(-)(g)) are much lower than k(SO + CS); hence, it is predicted that these two product channels do not contribute significantly to the overall rate coefficient.     

A Simple Method for Reliable Estimation of the Bubble Energy in the Underwater Explosion

The bubble energy is the main part of the chemical energy of the explosive that is formed upon the propagation of a shock wave through the water for the underwater explosion. A simple method is introduced for reliable prediction of the bubble energy of composite explosives containing aluminum (Al) and/or ammonium perchlorate (AP). It is shown that the bubble energy of composite Al/AP explosives depends on the number of moles of chlorine, carbon, and Al atoms. Experimental data of 56 composite Al/AP explosives are used to construct and test the novel model of the bubble energy. Statistical parameters of the new model, in external validation containing 35 composite Al/AP explosives as the training set, have the values 0.43 and 1.15 MJ · kg^–1 for the root mean squared error (RMSE) and maximum of errors (Max Error) of the new model, respectively. The values of RMSE and Max Error for 21 composite Al/AP explosives as test set are also 0.60 and 2.22 MJ · kg^–1, respectively. Cross validations of the new method corresponding to the coefficients of determination for leave‐one‐out (Q²_LOO) and the fivefold cross validation (Q²_5CV) are 0.8573 and 0.8403, respectively, which confirms goodness‐of‐fit, goodness‐of‐prediction, accuracy and precision of the novel model. It is shown that the novel correlation can be applied for pure and composite explosives, which do not contain Al/AP.     

Cyclotrimerization of butyl and cyclohexyl isocyanate—catalysis and kinetics

The cyclotrimerization of model aliphatic and cycloaliphatic isocyanates (butyl and cyclohexyl isocyanate) was carried out using an ammonium carboxylate and a salicylaldehyde-potassium complex as catalysts. The kinetics of the cyclotrimerization of butyl isocyanate in both 2-ethoxyethyl acetate and dimethylformamide (DMF) using the 2-ethylhexanoate salt of trimethylaminopropanol-2 was found to be of first order with respect to the isocyanate and also of first order with respect to the catalyst. The reaction rate in DMF was considerably greater than in 2-ethoxyethyl acetate, as could be expected. Employing the salicylaldehyde-potassium catalyst, the cyclotrimerization of butyl isocyanate followed second-order kinetics with respect to the isocyanate and first order with regard to the catalyst. Due to the fact that the cyclotrimerization of cyclohexyl isocyanate was found to be slower than that of butyl isocyanate, the cyclotrimerization of this isocyanate was carried out only in DMF using the 2-ethylhexanoate salt of trimethylaminopropanol-2 as the catalyst. The kinetics of this reaction was found to follow second order with respect to the isocyanate and first order with regard to the catalyst. The products of the reactions were identified by IR, ¹H-NMR, and mass spectrometry.     

A fast on-chip profiler memory using a pipelined binary tree

We introduce a novel memory architecture that can count the occurrences of patterns on a system's bus, a task known as profiling. Such profiling can serve a variety of purposes, like detecting a microprocessor's software hot spots or frequently used data values, which can be used to optimize various aspects of the system. The memory, which we call ProMem, is based on a pipelined binary search tree structure, yielding several beneficial features, including nonintrusiveness, accurate counts, excellent size and power efficiency, very fast access times, and the use of standard memories with only simple additional logic. The main limitation is that the set of potential patterns must be preloaded into the memory. We describe the ProMem architecture, and show excellent size and performance advantages compared with content-addressable memory (CAM) based designs.     

Modeling of solid state power amplifiers (sspa) and validation by means of a system simulator

A new model is presented in order to simulate the non-linear behavior of solid state power amplifiers. This model is based on static, together with dynamic measurements. The model has been validated through the use of the COSSAP system simulator. A good agreement has been found between measured and calculated curves, such as noise power ratio (npr) and bit error rate (BER)curves.     

Pre-concentration and quantification of aluminum in fish samples using a dispersive liquid–liquid micro-extraction–spectrofluorimetric method based on Al(III)–8-hydroxyquinoline complex’s fluorescence properties

A simple and fast dispersive liquid–liquid micro-extraction (DLLME)–spectrofluorimetric technique was developed and validated for the extraction and quantification of trace amounts of Al in fish samples, where 8-hydroxyquinoline was utilized as a spectrofluorimetric probe. In order to optimize the efficacy of the DLLME technique, the impact of experimental parameters on the extraction of Al(III) from fish samples was evaluated. Under the optimal conditions, the method was linear in the concentration range of 0.1–7.0 μg/g (r = 0.9996) with a LOD of 0.092 μg/g; additionally, the method was accurate (RE% of ? 3.0 to + 10.0%), precise (RSD% of 1.2–14.3%) and robust (RSD% of 3.8 and p value of 0.21) and its recovery was in the range of 97.0 ± 3.89–110.0 ± 12.5%; moreover, samples were stable before and during the analyses. Therefore, it can be claimed that the developed method could be successfully applied for the quantification of Al in fish samples.     

Nanostructured Hydrotalcite-Supported RuBaK Catalyst for Direct Conversion of Ethylene to Propylene

A novel nanostructured hydrotalcite-supported alkali-doped ruthenium-based catalyst is introduced for the direct gas-phase conversion of ethylene to propylene at 70°C and 1 atm. The maximum conversion of ca. 87% was obtained at the initial time on stream with a 65% selectivity to propylene and a 6% selectivity to butenes via consecutive reactions. Both conversion and selectivity to olefinic products decreased after 24 min of operation, however.