No abstract

Background Even though dermatologists often perform drug delivery procedures, it is necessary to assess their safety. Objective Quantify the amount of medication delivered using the MMP drug delivery technique and outline other safety parameters. Methods Using a simple and novel technique, we attempted to quantify the amount of medication delivered by weighing human skin samples before and after delivery. Results In drug delivery done on human skin using a liquid with a density of 1,271,460 μg/ml (the values expressed in this manuscript are in µg), a needling density of 570 perforations/cm2, and a needling depth of 300 microns, we estimate that 1,175 μg/cm2 were delivered (standard deviation 601 μg/cm2, standard error 190 μg/cm2). Limitations This result is only applicable to the protocol proposed in this study for the MMP drug delivery technique. Conclusion The MMP drug delivery technique injects small amounts of medication (1,175 μg/cm2) homogeneously into the dermis.

No abstract

Phenolic resin has long been used as matrix for composites mainly because of its flame retardant behavior and high char yield after pyrolysis, which results in a self supporting structure. The addition of ceramic powders, such as SiC and B 4 C, as fillers to the phenolic resin, results in better thermo-oxidative stability, but as drawbacks, it has poor homogeneity, adhesion and processing difficulties during molding of the composites. The addition of single elements, such as boron, silicon and phosphorus in the main backbone of the thermo-set resin is a new strategy to obtain special high performance resins, which results in higher mechanical properties, avoiding the drawbacks of simply adding fillers, which results in enhanced thermo-oxidative stability compared to conventional phenol-formaldehyde resins. Therefore, the product can have several applications, including the use as ablative thermal protection for thermo-structural composites. This work describes the preparation of a boron-modified phenolic resin (BPR) using salicyl alcohol and boric acid. The reaction was performed in refluxing toluene for a period of four hours, which produced a very high viscosity amber resin in 90% yield.The final structure of the compound, the boric acid double, substituted at the hydroxyl group of the aromatic ring, was determined with the help of the Infrared Spectroscopy, 1 H-NMR, TGA-DSC and boron elemental analysis. The absorption band of the group B-O at 1349 cm-1 can be visualized at the FT-IR spectrum. 1 H-NMR spectra showed peaks at 4.97-5.04 ppm and 3.60-3.90 ppm assigned to belong to CH 2 OH groups from the alcohol. The elemental analysis was also performed for boron determination.The product has also been tested in carbon and silicon fibers composite for the use in thermal structure. The results of the tests showed composites with superior mechanical properties when compared with the conventional phenolic resin.

No abstract

Thermal aging of hydroxy-terminated polybutadiene/isophorone diisocyanate (HTPB/IPDI)-based polyurethane was studied as a function of NCO/OH ratio (1.0 and 0.85). Samples were aged in air ovens at 50, 60, 65, and 70 °C for periods of time from 1 to 34 weeks. Changes in chemical (swelling testing and FT-IR spectroscopy) and mechanical (tension testing and hardness) properties were evaluated throughout the aging assays. Correlation between equilibrium swelling ratio and elastic modulus, coupled with changes in FT-IR spectra, indicated oxidative cross-linking as the dominant mechanism for both molar ratios investigated. However, determination of Arrhenius activation energy resulted in values of (82 ± 10) kJ.mol -1 and (156 ± 30) kJ.mol -1 for 1.0 and 0.85 NCO/OH ratios, respectively, thus revealing faster oxidative degradation kinetics for higher urethane linkage networks.

The main objective of these studies was the synthesis and characterization of new energetic binders and their use in some propellant formulations. Following the working plan elaborated, the synthesis and characterization of the following compounds has been done successfully:The scale up for the synthesis of copolymer GAP/PolyBAMO and PolyBAMO using GAP as initiator has been done and they were fully characterized by IR, ( 1 H, 13 C) NMR-spectroscopy, GPC, elemental analysis, OH-functionality, differential scanning calorimetry (DSC) and sensitivity tests (friction, impact). For this two scale up synthesis some propellant formulations were carried out and the results of mechanical and burning properties have been compared with GAP propellants.

Fourier transform‐infrared spectroscopy (FT‐IR) in transmission and photoacoustic detection (PAS) techniques have been used for the characterization of polymeric coating of cyclotrimethylenetrinitramine (RDX) using a fluoroelastomer (Viton®). Although the bands of the polymer were indicated by two different techniques, the transmission (casting film) showed better evidence of absorption of fluoroelastomer for the polymer coating of the energetic material. Also attenuated total reflectance (ATR), another FT‐IR technique, has been used to analyze a cyclotetramethylenetetramine (HMX)/Viton system for the characterization of Viton bands and it showed excellent results without sample preparation.