Mild Method for Preparation of 4,4-Dimethyloxazoline Derivatives of Polyunsaturated Fatty Acids for GC–MS

A mild and convenient method has been developed for preparing 4,4-dimethyloxazoline (DMOX) derivatives of fatty acids for GC–MS analysis. First, fatty acid methyl esters are converted to corresponding amides by incubation overnight at room temperature with 2-amino-2-methyl-1-propanol and a catalytic amount of sodium methoxide. The resulting 2-(methylpropanol) amides were isolated by partition between hexane–diethyl ether and water, and then converted to 4,4-dimethyloxazoline derivatives by treatment with trifluoroacetic anhydride under mild conditions (50 °C for 45 min). Structures of 2-methylpropanol amide and a DMOX derivative of oleic acid were confirmed by GC–MS. This method was applied to different FAME prepared from animal, plant or microbial lipids. The suggested method is most suitable for structure analysis of polyunsaturated fatty acids (PUFA) and for acids with double bonds in close to terminal positions. Application of the method is illustrated with spectra of the DMOX derivatives of 16:1(n-13), 24:5(n-6) and 24:6(n-3) acids.     

Pharmaceuticals Removal by Adsorption with Montmorillonite Nanoclay

The problem of purifying domestic and hospital wastewater from pharmaceutical compounds is becoming more and more urgent every year, because of the continuous accumulation of chemical pollutants in the environment and the limited availability of freshwater resources. Clay adsorbents have been repeatedly proposed as adsorbents for treatment purposes, but natural clays are hydrophilic and can be inefficient for catching hydrophobic pharmaceuticals. In this paper, a comparison of adsorption properties of pristine montmorillonite (MMT) and montmorillonite modified with stearyl trimethyl ammonium (hydrophobic MMT-STA) towards carbamazepine, ibuprofen, and paracetamol pharmaceuticals was performed. The efficiency of adsorption was investigated under varying solution pH, temperature, contact time, initial concentration of pharmaceuticals, and adsorbate/adsorbent mass ratio. MMT-STA was better than pristine MMT at removing all the pharmaceuticals studied. The adsorption capacity of hydrophobic montmorillonite to pharmaceuticals decreased in the following order: carbamazepine (97%) > ibuprofen (95%) > paracetamol (63–67%). Adsorption isotherms were best described by Freundlich model. Within the pharmaceutical concentration range of 10–50 µg/mL, the most optimal mass ratio of adsorbates to adsorbents was 1:300, pH 6, and a temperature of 25 °C. Thus, MMT-STA could be used as an efficient adsorbent for deconta×ating water of carbamazepine, ibuprofen, and paracetamol.     

Structure formation of alkylammonium montmorillonites in organic media

Using adsorption, X-ray diffraction (XRD), rheological, electrokinetic, dielectric and calorimetric measurements, the mechanism for the gel formation of the alkylammonium derivatives of the Pyzhevsky montmorillonite (Ukraine) (OM) in organic liquids of different polarity was investigated. The influence of modification, type of the organic cations, length of the alkyl chain, type of organic liquid and polar additive as well as traces of water on the swelling volume, enthalpy of immersion, zeta potential and the Bingham yield stress of the organo-gels were evaluated.There exists a certain correlation between the swelling volume, the ability for gel formation and the basal spacing of OM (d₀₀₁), which depends on the size of the intercalated cation. Thermodynamical analysis indicates that the degree of swelling and the gel strength are determined by the energy of the layer cohesion, energy of the solvation, the electrostatic repulsion and entropy effects.The thickening of OM dispersions and gel formation is optimal when the surface coverage by alkylammonium ions reaches θ=0.85–1.0. The lyophilicity and zeta potential are then high but not too strong to cause complete peptization.The linear increase of rheological parameters of the organo-gels in benzene, toluene, p-xylene, o-xylene, chlorobenzene, benzonitrile and nitrobenzene is related to the increase of the polarization of the liquid molecules and the transition from positive to negative ζ-potentials and the enthalpy of immersion.The effect of protonic and aprotonic compounds on the rheological, electrokinetic and thermodynamic properties of the hydrocarbon gels of octadecyl benzyldimethylammonium montmorillonite was also studied. For homologue alcohols, this influence decreases with the increase of chain length, corresponding to the decrease of the adsorption and the dielectric permittivity (). The influence of the aprotonic compounds on the rheological properties and on the enthalpy of immersion does not correlate with , but this influence is larger when the polarization and electron donor ability of the polar molecules are higher.The maximal gel formation of the hydrocarbon-OM dispersions requires a certain amount of water, which corresponds to a monomolecular coverage of the polar surface centers. This effect is explained by the strong orientation of the adsorbed water molecules, which creates giant dipole moments on the particles and H-bonds between the particles.     

Kinetic Monte Carlo approach to modeling dislocation mobility

We describe a kinetic Monte Carlo (kMC) approach to modeling dislocation motion, directly linking the energetics of dislocation kink nucleation and migration on the atomistic scale with the experimental data on the microscale. A study of planar glide of screw dislocation in Si, an ideal test-bed for our method is first discussed, followed by preliminary results for a more complicated problem, three-dimensional motion of screw dislocation in BCC metals. We find that accuracy of the model predictions, even in the favorable case of Si, cannot claim to be quantitative because of uncertainties in the atomistic results for kink energetics. On the other hand, the kMC method is useful for qualitatively probing the mechanisms controlling dislocation motion, and it is capable of providing plausible explanation of some puzzling features of the experimental data.     

Aging of Vascular System Is a Complex Process: The Cornerstone Mechanisms

Aging is one of the most intriguing processes of human ontogenesis. It is associated with the development of a wide variety of diseases affecting all organs and their systems. The victory over aging is the most desired goal of scientists; however, it is hardly achievable in the foreseeable future due to the complexity and ambiguity of the process itself. All body systems age, lose their performance, and structural disorders accumulate. The cardiovascular system is no exception. And it is cardiovascular diseases that occupy a leading position as a cause of death, especially among the elderly. The aging of the cardiovascular system is well described from a mechanical point of view. Moreover, it is known that at the cellular level, a huge number of mechanisms are involved in this process, from mitochondrial dysfunction to inflammation. It is on these mechanisms, as well as the potential for taking control of the aging of the cardiovascular system, that we focused on in this review.     

Measurement of turbidity in linguistic scales

Translated from Izmeritel'naya Tekhnika, No. 8, pp. 18–19, August, 1989.     

Principles for Finding Matrices for Immobilizing High-Level Wastes

The principles for selecting matrices for immobilizing high-level wastes are examined. It is concluded that actinides should be separated and embeeded in the matrix separately from fission products. The minimum significant specific activity, regulated by NRB-99, cannot be used to estimate the storage time. It is suggested that such values be established as a function of the leach rate of radionuclides and matrix materials from matrices. For this, a standard leaching method using pulverized materials must be specified. Two criteria are proposed for comparing matrix materials.     

Synthesis and Characterization of the R27S Genetic Variant of Insulin‐like Peptide 5

We report the synthesis and in vitro bioactivity assessment for an insulin‐like peptide 5 (INSL5) analogue that was recently discovered as a genetic mutation in an Amish population. The mutation was associated with improved metabolic status, and receptor‐based antagonism was proposed as a potential mechanism for the altered phenotype. We determined the specific peptide analogue to be fully potent and of maximal efficacy at the human relaxin family peptide receptor 4 (RXFP4), suggesting an alternative basis for the observed effect. In preparation of this synthetically challenging hormone, we have introduced several improvements such as implementation of isoacyl chemistry for high‐efficiency preparation of INSL5 B‐chain and selective intramolecular A6‐11 disulfide formation as a first step in sequential disulfide assembly.     

Lidar and satellite temperature measurements during the sudden stratospheric warmings over Siberia and the Russian Far East in 2008–2012

This article presents a comprehensive study of disturbances of the temperature regime of the Earth’s stratosphere, which are related to sudden stratospheric warmings over Western and Eastern Siberia and the Russian Far East in the winters of 2008–2012. This study is based on data obtained using temperature remote-sensing techniques (lidar and satellite ones). The analysis rests on data on vertical temperature distribution in the stratosphere, obtained from lidar measurements over regions of Tomsk (56°N, 85°E), Yakutsk (61°N, 130°E), and Paratunka, the Kamchatka territory (53°N, 158°E). For complex analysis of the spatial–temporal temperature distribution in the middle atmosphere, the lidar measurement data are applied along with satellite data on temperature acquired by the microwave limb sounder on the Earth Observing System Aura satellite. We consider the regional effects of sudden stratospheric warmings that were observed over the Asian region of Russia (~85–160°E) in the winters of 2008–2012. There were stratospheric warmings over the Asian region of Russia each winter during the period under consideration, as deduced from lidar and satellite measurements of temperature. Lidar and satellite measurements of temperature have evidenced the previously known peculiarities of the development of winter stratospheric warmings. On the whole, lidar and satellite measurements of height distribution of temperatures agree. Possible reasons for the divergences under consideration are discussed.