Creation of a functional polysiloxane layer on the surface of magnetic nanoparticles using the sol-gel method

The developed methods using tetraethoxysilane and trifunctional silanes were applied to obtain Fe₃O₄ magnetic particles that contain amino groups with compositions of ≡Si(CH₂)₃NH₂, ≡Si(CH₂)₃NH(CH₂)₂NH₂, and [≡Si(CH₂)₃]₂NH. The XRD data show that the nuclei of nanoparticles in the obtained materials preserve the structure of the primary carrier, namely, that of Fe₃O₄ magnetite. The thermograms show a high thermal stability of the applied surface layers, i.e., their destruction was found to start at temperature above 250°C. The DRIFT spectra indicate the formation of the silica bond framework in the surface layers of nanoparticles and also the existence of hydrogen bonds between amino groups and silanol groups with the participation of water molecules aided. All of the obtained materials exhibit magnetic properties and offer promising application in medicine.     

Structural and adhesion properties of poly(ethyl 2-cyanoacrylate) post-cured at different temperatures and times

The structure and properties of poly(ethyl 2-cyanoacrylate)s (pECNs) cured at 25?°C during 24?hours, and post-cured at different temperatures (45-90?°C) and times (2-6?hours) were studied. Irrespective of the post-cure conditions, pECN was not fully polymerized and two different structures of different molecular weights and topographies were obtained. The post-cure decreased the shear strength values in joints made with aluminum and ethyl cyanoacrylate due to the decrease in the percentage of higher molecular weight polymeric chains and the formation of new short polymeric chains by unzipping de-polymerization mechanism, both contributed to decrease the mechanical properties. On the other hand, the post-cure changed the morphology of pECN because of nano-spheres were produced by curing at 25?°C which were not present after post-cure at 90?°C.     

Structural dependence of chemical durability in modified aluminoborate glasses

Alkali and alkaline earth aluminoborate glasses feature high resistance to cracking under sharp contact loading compared to other oxide glasses. However, due to the high content of hygroscopic B₂O₃, it is expected that applications of these glasses could be hindered by poor chemical durability in aqueous solutions. Indeed, the compositional and structural dependence of their dissolution kinetics remains unexplored. In this work, we correlate the dissolution rates of aluminoborate glasses in acidic, neutral, and basic solutions with the structural changes induced by varying the aluminum-to-boron ratio. In detail, we investigate a total of seventeen magnesium, lithium, and sodium aluminoborate glasses with fixed modifier content of 25 mol%. We show that the structural changes induced by alumina depend on the network modifier. We also demonstrate a correlation between the chemical durability at various pH values and the structural changes in Mg-, Li- and Na-aluminoborate glasses. The substitution of alumina by boron oxide leads to a general decrease in chemical corrosion in neutral and acidic solutions. The lowest dissolution rate value is observed in Mg-aluminoborate glasses, as a consequence of the intermediate character of magnesium which can increase the network cross-linking. For basic solutions, the chemical durability is almost constant for the different amount of alumina in the three series, likely because B₂O₃ is susceptible to nucleophilic attack, which is favored in high-OH⁻ solutions.     

Determination of trans fatty acids and fatty acid profiles in margarines marketed in spain

Two gas chromatography (GC) procedures were compared for routine analysis of trans fatty acids (TFA) of vegetable margarines, one direct with a 100-m high-polarity column and the other using argentation thin-layer chromatography and GC. There was no difference (P>0.05) in the total trans 18∶1 percentage of margarines with a medium level of TFA (∼18%) made using either of the procedures. Both methods offer good repeatability for determination of total trans 18∶1 percentage. The recoveries of total trans isomers of 18∶1 were not influenced (P>0.1) by the method used. Fatty acid composition of 12 Spanish margarines was determined by the direct GC method. The total contents of trans isomers of oleic, linoleic, and linolenic acids ranged from 0.15 to 20.21, from 0.24 to 0.99, and from 0 to 0.47%, respectively, and the mean values were 8.18, 0.49, and 0.21%. The mean values for the ratios [cis-polyunsaturated/(saturated +TFA)] and [(cis-polyunsaturated + cis-monounsaturated)/(saturated +TFA)] were 1.25±0.39 and 1.92±0.43, respectively. Taking into account the annual per capita consumption of vegetable margarine, the mean fat content of the margarines (63.5%), and the mean total TFA content (8.87%), the daily per capita consumption of TFA from vegetable margarines by Spaniards was estimated at about 0.2 g/person/d.     

Effect of <Emphasis Type="Italic">β</Emphasis>-Cyclodextrin on <Emphasis Type="Italic">trans</Emphasis> Fats,CLA, PUFA and Phospholipids of Milk Fat

The aim of this study was to evaluate the effect of β-cyclodextrin (β-CD) on trans C18:1 fatty acid isomers, conjugated linoleic acid (CLA), polyunsaturated fatty acids (PUFA) and phospholipids in pasteurized milk. The individual trans C18:1 isomers were not significantly affected by the β-CD. trans-11 C18:1 (vaccenic acid) was found to be the major isomer (1.31 ± 0.12%) followed by trans-15 C18:1 (0.35 ± 0.06%). Individual trans linoleic acids did not show differences from the effect of β-CD, representing the high amount of the isomer trans-11 cis-15 C18:2 (0.433 ± 0.087%). The main CLA isomer cis-9 trans-11 C18:2 (rumenic acid) did not show differences between the control milk (0.672 ± 0.080%) and β-CD milk (0.663 ± 0.074%). PUFA and omega-3 and -6 fatty acids were not also significant by the effect of β-CD. Total phospholipids were not significantly affected by effect of the β-CD (0.023 ± 0.001% vs. 0.022 ± 0.001%). β-CD is a effective oligosaccharide for cholesterol removal from pasteurized milk and does not significantly affect the lipid components of the milk fat.     

Characterization of grape seed oil from different grape varieties (Vitis vinifera)

In this work, oil obtained from seeds of different red grape varieties, grown in the Autonomous Regions of Castilla‐La Mancha and Murcia (Spain), was characterized by determining physicochemical and sensory quality parameters, stability, and the composition in fatty acids and sterols. The physicochemical quality parameters (free acidity, peroxide index, K₂₇₀ and wax) scored high (meaning low quality) compared with virgin olive oils, while the negative sensory attributes stood out over the positive ones. Therefore, the oil was not considered suitable for table use without undergoing a refining process. The samples showed high linoleic and low linolenic acid contents, while β‐sitosterol was the main sterol found. Drying grape seeds with hot air before extraction gave higher physicochemical quality, total phenolic content and stability, and lower wax content in comparison to air‐drying of seeds. The drying process affected the sterol composition but not the fatty acid composition.     

Discovery of Riociguat (BAY 63‐2521): A Potent,Oral Stimulator of Soluble Guanylate Cyclase for the Treatment of Pulmonary Hypertension

Direct stimulation of soluble guanylate cyclase (sGC) represents a promising therapeutic strategy for the treatment of a range of diseases, including the severely disabling pulmonary hypertension (PH). Optimization of the unfavorable DMPK profile of previous sGC stimulators provided riociguat, which is currently being investigated in phase III clinical trials for the oral treatment of PH.

     

Thermo‐mechanical properties of candelilla wax and dotriacontane organogels in safflower oil

The thermo‐mechanical properties of organogels developed by a complex mixture of n‐alkanes present in candelilla wax (CW) were investigated and compared with the ones of organogels developed by a pure n‐alkane, dotriacontane (C₃₂). In both cases, the liquid phase used was safflower oil high in triolein (SFO) and the variables studied were two levels of gelator concentration (1 and 3%), cooling rates of 1 and 10 °C/min, and two gel setting temperatures, 5 and 25 °C (T_set). Based on comparisons of the organogels made with C₃₂, the presence of minor molecular components in CW had a profound effect on the crystal habit of the n‐alkanes in CW‐based organogels, and therefore on their physical properties. Thus, independent of the cooling rate and T_set, C₃₂ showed a higher solubility and higher self‐assembly capability in the SFO than CW. Nevertheless, for the same gelator concentration and time‐temperature conditions, C₃₂ organogels had lower G' profiles than CW organogels. Additionally, independent of the type of gelator, more stable organogel structures were developed at T_set = 5 °C and using the lower cooling rate. The rheological behavior of the organogels was explained considering the formation of a rotator phase by the n‐alkanes, its solid‐solid transition, and their dependence as a function of the cooling rate and T_set. The results here obtained showed that it is possible to gelate SFO through organogelation with CW and without the use of trans fats.     

Nafion-clay hybrids with a network structure

Nafion-clay hybrid membranes with a unique microstructure were synthesized using a fundamentally new approach. The new approach is based on depletion aggregation of suspended particles - a well-known phenomenon in colloids. For certain concentrations of clay and polymer, addition of Nafion solution to clay suspensions in water leads to a gel. Using Cryo-TEM we show that the clay particles in the hybrid gels form a network structure with an average cell size in the order of 500 nm. The hybrid gels are subsequently cast to produce hybrid Nafion-clay membranes. Compared to pure Nafion the swelling of the hybrid membranes in water and methanol is dramatically reduced while their selectivity (ratio of conductivity over permeability) increases. The small decrease of ionic conductivity for the hybrid membranes is more than compensated by the large decrease in methanol permeability. Lastly the hybrid membranes are much stiffer and can withstand higher temperatures compared to pure Nafion. Both of these characteristics are highly desirable for use in fuel cell applications, since a) they will allow the use of a thinner membrane circumventing problems associated with the membrane resistance and b) enable high temperature applications.