Spacer effect on triazole-linked sugar-based surfactants

A series of alkyl triazole glycoside surfactants, ATGs, differing in the length of the alkyl linker between the sugar and the triazole, was synthesized and investigated on their surfactant properties and phase behavior in water. The results indicate no significant impact of the linker on surface and interphase properties, whereas the phase behavior is affected. Higher affinity for the bicontinuous cubic phase potentially favors methylene-linked ATGs over higher homologs for drug-delivery applications. A comparison of glucose and xylose reveals a tendency for high Krafft points for propargyl xyloside based ATGs. This disfavors these surfactants with respect to both glucose analogs and higher homologs.     

Green synthesis of ZnCo<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles by <Emphasis Type=Italic>Aloe albiflora</Emphasis> extract and its application as catalyst on the thermal decomposition of ammonium perchlorate

This work aimed the evaluation of pH influence in the obtainment of composites from palygorskite (PAL) and chitosan (CS). The materials PAL/CS-1 and PAL/CS-2 were obtained by similar methodology with modified pHs: 5.0 ± 0.5 and 11.0 ± 0.5, respectively. Both materials were evaluated for specific surface area analysis, elemental analysis, XRD, FTIR, thermal analysis, MEV and interaction drug composite, using 5-aminosalicylic acid (5-ASA) as model. The surface area analysis data showed the reduction in PAL/CS-2 related to CS presence on surface in contrast with PAL/CS-1, which corroborate with elemental analysis present nine times more of CS in PAL/CS-2 composition. Regarding to XRD data, the interaction of CS with PAL did not cause modification in clay structure in PAL/CS-2. These results were confirmed by FTIR data with the N–H deformation vibration in PAL/CS-2 while PAL/CS-1 was invariable to PAL. In thermal analysis, results were observed 60.2% residual mass to PAL/CS-2, which it was lower than PAL (87.2%) and PAL/CS-1 (86.7%), due to CS decomposition which had enthalpy energy of 62.1 J g^?1 K^?1, confirming the data previously cited. PAL/CS-2 presented 5-ASA adsorption of 7.9 mg g^?1, which was inferior to others probably caused by scarcity of active sites of PAL already occupied by CS. These results showed that pH control was fundamental to enhance efficiency of obtainment of composite in basic pH because the decrease in CS protonation degree increasing interaction between this one and PAL, although it contributed to decrease in 5-ASA adsorption due to low availability of interaction sites.     

Surfactant effects on the particle size,zeta potential,and stability of starch nanoparticles and their use in a pH-responsive manner

Storage conditions seem to be important in the long-term stability of nanoparticles (NPs). This work studies the effects of surfactants and storage container on particle size distribution and zeta potential during long-term storage of acid hydrolyzed potato starch NPs. The NPs were prepared from potato starch using acid hydrolysis and high-intensity ultrasonication. During the ultrasonic treatment, the surfactants were added dropwise to the solutions to reduce the size and stabilize the formed NPs. Particle size distribution, zeta potential, and FE-SEM were used to characterize the ensuing NPs. Additionally, a 5-month stability study was performed to evaluate the maintenance of potato starch NPs over time at different storage conditions. Then, NPs from corn starch were produced by the same procedure and were used for preparing pH-responsive nanocarriers containing NaHCO₃ for delivery of an anti-cancer drug, FTY720. These NPs were able to release the drug at pH 5.0 because of CO₂ generated from NaHCO₃ in acidic pH and released from the NPs by the production of pores, which accelerate drug release.     

Static Headspace GC/MS Method for Determination of Methanol and Ethanol Contents,as the Degradation Markers of Solid Insulation Systems of Power Transformers

Methanol in insulating oil has been proposed as a new marker for condition assessment of the solid insulation system of power transformers. In the current work, as a first step of using the new marker, an analytical static headspace gas chromatography/mass spectrometry method has been developed, optimized, and validated to measure methanol and ethanol contents in the insulating mineral oil. The analyzing setup consists of a 6890 N gas chromatograph equipped with a 5973 network mass spectrometer (MS) in the absence of a costly headspace autosampler, and the chromatography separation was performed on a 60 m × 320 µm × 0.5 µm VF-WAXms GC column. Calibration curves have been provided using several concentrations of the alcohols, and also limit of detection (LOD), limit of quantification (LOQ), and relative standard deviation percentage (RSD%) have been determined.     

Well‐defined polyisoprene‐grafted silica nanoparticles via the RAFT process

The preparation of well‐defined polyisoprene‐grafted silica nanoparticles (PIP‐g‐SiO₂ NPs) was investigated. Surface initiated reversible addition fragmentation chain transfer (SI‐RAFT) polymerization was used to polymerize isoprene from the surface of 15 nm silica NPs. A high temperature stable trithiocarbonate RAFT agent was anchored onto the surface of particles with controllable graft densities. The polymerization of isoprene mediated by silica anchored RAFT with different densities were investigated and compared to the polymerization mediated by free RAFT agents. The effects of different temperatures, initiators, and monomer feed ratios on the kinetics of the SI‐RAFT polymerization were also investigated. Using this technique, block copolymers of polyisoprene and polystyrene on the surface of silica particles were also prepared. The well‐defined synthesized PIP‐g‐SiO₂ NPs were then mixed with a polyisoprene matrix which showed a good level of dispersion throughout the matrix. These tunable grafted particles have potential applications in the field of rubber nanocomposites. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1493–1501     

Flexible polyfluorinated bis-diazirines as molecular adhesives

Motivated by a desire to develop flexible covalent adhesives that afford some of the same malleability in the adhesive layer as traditional polymer-based adhesives, we designed and synthesized two flexible, highly fluorinated bis-diazirines. Both molecules are shown to function as effective crosslinkers for polymer materials, and to act as strong adhesives when painted between two polymer objects of low surface energy, prior to thermal activation. Data obtained from lap-shear experiments suggests that greater molecular flexibility is correlated with improved mechanical compliance in the adhesive layer.

Flexible, highly fluorinated covalent adhesives are synthesized, and are shown to afford comparable C–H insertion efficiency and adhesion strength relative to a rigid analogue, while providing improved mechanical compliance in the adhesion layer.     

Effects of nitrogen-containing functional groups of reduced graphene oxide as a support for Pd in selective hydrogenation of cinnamaldehyde

Research on Chemical Intermediates - The importance of electronic and chemical properties of nitrogen-doped reduced graphene oxide (NRGO) has attracted more attention in recent years. Various...     

Armatans A and B,New Antimicrobial Isoflavans from Colutea armata

Chemistry of Natural Compounds - Armatans A (1) and B (2), new isoflavans, have been isolated from the EtOAc-soluble fraction of the MeOH extract of Colutea armata Hemsl. &amp; Lace, along with...     

Electrosprayed Shrimp and Mushroom Nanochitins on Cellulose Tissue for Skin Contact Application

Cosmetics has recently focused on biobased skin-compatible materials. Materials from natural sources can be used to produce more sustainable skin contact products with enhanced bioactivity. Surface functionalization using natural-based nano/microparticles is thus a subject of study, aimed at better understanding the skin compatibility of many biopolymers also deriving from biowaste. This research investigated electrospray as a method for surface modification of cellulose tissues with chitin nanofibrils (CNs) using two different sources—namely, vegetable (i.e., from fungi), and animal (from crustaceans)—and different solvent systems to obtain a biobased and skin-compatible product. The surface of cellulose tissues was uniformly decorated with electrosprayed CNs. Biological analysis revealed that all treated samples were suitable for skin applications since human dermal keratinocytes (i.e., HaCaT cells) successfully adhered to the processed tissues and were viable after being in contact with released substances in culture media. These results indicate that the use of solvents did not affect the final cytocompatibility due to their effective evaporation during the electrospray process. Such treatments did not also affect the characteristics of cellulose; in addition, they showed promising anti-inflammatory and indirect antimicrobial activity toward dermal keratinocytes in vitro. Specifically, cellulosic substrates decorated with nanochitins from shrimp showed strong immunomodulatory activity by first upregulating then downregulating the pro-inflammatory cytokines, whereas nanochitins from mushrooms displayed an overall anti-inflammatory activity via a slight decrement of the pro-inflammatory cytokines and increment of the anti-inflammatory marker. Electrospray could represent a green method for surface modification of sustainable and biofunctional skincare products.