Alternative Diesel Fuel: Microemulsion Phase Behavior and Combustion Properties

The phase behavior of water, diesel, limonene, and ethanol was investigated at ambient temperature using single nonionic alkyl polyglycol ethers (C₁₄E₃). Visual inspection as well as crosspolarizers was used to detect transparency and anisotropy. Ternary phase diagrams were determined. Combustion experiments using a four-cylinder diesel engine were carried out. Isotropic water in diesel microemulsion region (L₂) and anisotropic liquid crystalline region (LC) were found with all combinations. Increasing the ratio of limonene to diesel reduced the microemulsion region while the presence of ethanol increased it on the expense of the LC region. Combustion tests performed on a selected formulation from the ternary phase diagram of water, diesel, ethanol, and C₁₄E₃ revealed substantial reduction of soot, NO_x, and CO₂ emissions compared to neat diesel.     

Synthetic Approaches to Trifluoromethoxy‐Substituted Compounds

Because of the unique properties of the trifluoromethoxy group, molecules bearing this moiety will find applications in various fields, particularly in the life sciences. However, despite the great interest in this functional group, only a small number of trifluoromethoxylated molecules are currently synthetically accessible. Over the last few years, several innovative and promising strategies for the synthesis of trifluoromethoxylated compounds have been described. This Minireview discusses these existing methods with a particular focus on more recent advances.     

Rietveld refinement and vibrational spectroscopic study of alunite from el Gnater, central Tunisia

The crystal structure of alunite (K_0.72,Na_0.28) Al₃(SO₄)₂(OH)₆ from El Gnater, central Tunisia, is refined by the Rietveld method. Raman and infrared data of this mineral are also given in order to provide some further information about the mineralogy and chemistry of this alunite. The crystal system is trigonal, space group R $ \bar 3 The crystal structure of alunite (K_0.72,Na_0.28) Al₃(SO₄)₂(OH)₆ from El Gnater, central Tunisia, is refined by the Rietveld method. Raman and infrared data of this mineral are also given in order to provide some further information about the mineralogy and chemistry of this alunite. The crystal system is trigonal, space group R m, with a = 6.9834(4) ? and c = 17.0899(11) ?. Final Rietveld refinement converges to R _p = 0.16, R _wp = 0.16, and R _Bragg = 0.07. In the alkalic site, the occupancy of potassium and sodium is refined to 72 and 28%, respectively. The Raman and infrared spectra are investigated in order to improve previous assignments of the observed frequencies, especially for tetrahedral and octahedral vibration and OH group, which are discussed on the basis of unit-cell group analysis and by comparison with previously observed wavenumbers of natrojarosite and synthetic alunite. The text was submitted by the authors in English.     

Inclined surface slip flow of nanoparticles with subject to mixed convection phenomenon: Fractional calculus applications

The interest of researchers towards the nanofluids is noticed in recent years due to leading applications in thermal systems and industrial framework. Referring to such motivations, current study explores the role of velocity slip effects for the mixed convection flow of nanofluid endorsed due to inclined surface. The Casson base fluid model for which the thermal impact needs to be improved. The analysis is observed when the role of velocity slip is important. The modeling of unsteady free convective flow problem yields partial differential system. The Atangana-Baleanu (AB) and Caputo-Fabrizio (CF) fractional operators are implemented in order to simulates the computation of problem. The graphical presentations are prepared in order to check the physical dynamic of parameters.     

Bioactive Electroconductive Hydrogels: The Effects of Electropolymerization Charge Density on the Storage Stability of an Enzyme-Based Biosensor

Electrode-supported hydrogels were conferred with the biospecificity of enzymes during the process of electropolymerization to give rise to a class of bioactive, stimuli-responsive co-joined interpenetrating networks of inherently conductive polymers and highly hydrated hydrogels. Glucose responsive biotransducers were prepared by potentiostatic electropolymerization [750 mV vs. Ag/AgCl (3 M KCl)] of pyrrole at Poly(hydoxyethyl methacrylate)-based hydrogel-coated Pt micro-electrodes (Φ = 100 μm) from aqueous solutions of pyrrole and glucose oxidase (GOx; 0.4 M pyrrole, 1.0 mg/ml GOx) to 1.0 and 10.0 mC/cm². Polypyrrole was them over-oxidized by cyclic voltammetry (0–1.2 V vs. Ag/AgCl, 40 cycles in PBKCl, pH = 7.0). Biotransducers were stored at 4 °C in PBKCl for up to 18 days. Amperometric dose–response at 0.4 V vs. Ag/AgCl followed by Lineweaver–Burk analysis produced enzyme kinetic parameters as a function of electropolymerization charge density and storage time. Apparent Michaelis constant (K _Mapp) increased from 18.6–152.0 mM (1.0 mC/cm²) and from 2.7–6.1 mM (10.0 mC/cm²). Biotransducer sensitivity increased to 21.2 nA/mM after 18 days and to 12.8 pA/mM after 10 days for the 1.0 and 10.0 mC/cm² membranes, respectively. Maximum current, I _max, also increased over time to 2.7 nA (1.0 mC/cm²) and to 170 pA (10.0 mC/cm²). Electropolymerization of polypyrrole is shown to be an effective means for imparting bioactivity to a hydrogel-coated microelectrode. GOx was shown to be stabilized and to increase activity over time within the electroconductive hydrogel.     

Contribution to the study of structural and elastic properties of wüstite under pressure up to 140 GPa by pseudopotential calculations

Using first-principles calculations based on the density functional theory and the generalized gradient approximations, we have studied the effect of high pressures up to 140 GPa on the structural and elastic properties of wüstite. Our results indicate that FeO undergoes a structural phase transition from NaCl-type (B1) to NiAs-type (B8) almost at the pressure of 77 GPa. The density increases across this transition by about 5%, which is a higher value than that obtained in other researches. We can clearly present the wüstite elastic properties and isotropic wave velocities which are not already studied in this range of pressure, and we could compare these results with the available experiment data, especially with that of PREM model.     

Pyridine- and pyrimidine-2-thiolate complexes of ruthenium

A series of mononuclear ruthenium complexes containing pyridine- and pyrimidine-2-thiolato ligands was prepared and characterized. The new compounds of general formula CpRu(PPh₃)(κ²S,N-SR) (1) (SR = pyridine-2-thiolate (a), pyrimidine-2-thiolate (b)) were prepared directly by reacting the thiolato anions (RS⁻) with CpRu(PPh₃)₂Cl. Complexes 1 readily react with NOBF₄ or CO in THF at room temperature to give [CpRu(PPh₃)(NO)(κ¹S-HSR)][BF₄]₂ (2) and CpRu(PPh₃)(CO)(κ¹S-SR) (3), respectively. The one-pot reaction of CpRu(PPh₃)₂Cl, thiolato anions and bis(diphenylphosphino)ethane (dppe) gave CpRu(dppe)(κ¹S-SR) [dppe: Ph₂PCH₂CH₂PPh₂ (4)]. The complex salts, [CpRu(PPh₃)₂(κ¹S-HSR)]BPh₄ (5) are prepared by mixing CpRu(PPh₃)₂Cl, HSR and NaBPh₄ at room temperature. The structures of CpRu(PPh₃)(κ²S,N-Spy) (1a), [CpRu(PPh₃)(NO)(κ¹S-HSpy)][BF₄]₂ (2a) and CpRu(PPh₃)(CO)(κ¹S-Spy) (3a), (py = C₅H₄N) have been determined.     

Chemical compounds from Phoenician juniper berries (Juniperus phoenicea)

Natural chemical compounds are a widely researched topic worldwide because of their potential activity against cerebrovascular diseases. Chemicals from Juniperus phoenicea berries are reported in this study. Lipids (11%) from seeds are mainly unsaturated (86%). Minerals are also quantified like Na (63.8?mg per 100?g?DW) or K (373.9?mg per 100?g?DW). Total reduced sugars are ca 192.6?mg?g(-1)?DW. Polyphenols and flavonoids from berries are highly present with an average of 1764?±?174.3?mg gallic acid per 100?g?DW and 890?±?47.6?mg rutin per 100?g?DW, respectively. Mean free radical scavenging activities, determined by DPPH and ABTS, are 1337?±?126.2?mM TEAC per 100?g?DW and 1105.7?±?95.9?mM TEAC per 100?g?DW, respectively. All findings improve the possible presence of biologically active fractions in phytocomplex that could be used as such and/or extracted for the formulation of supplements and/or ingredients for the pharmaceutical industry.