Matrices of poly(styrene‐co‐maleic anhydride) with surface containing functional anhydride groups of different percentage was prepared by solution polymerization. Ampicillin was bound on the surface of this matrix by chemical bonding in organic medium. The amount of Ampicillin chemically bound to the matrix was spectroscopically characterized and the in vitro release rate of Ampicillin in weakly basic medium was established along with the determination of its antimicrobial activity. This prodrug allows a prolonged release (6–8 days) of the drug.

Losartan (LST) is the first orally active nonpeptide angiotensin-II receptor antagonist with an improved safety and tolerability profile. It is prescribed alone or in combination with hydrochlorothiazide (HCTZ) for the treatment of moderate-to-severe hypertension. This paper describes the development of 2 methods that use different techniques, first-derivative spectroscopy and high-performance thin-layer chromatography (HPTLC), to determine LST and HCTZ in the presence of each other. LST and HCTZ in combined preparations were quantitated by using the first-derivative responses at 271.6 nm for LST and 335.0 nm for HCTZ in spectra of their solutions in water. The linearity ranges are 30–70 μg/mL for LST and 7.5–17.5 μg/mL for HCTZ with correlation coefficients of 0.9998 and 0.9997, respectively. In the HPTLC method, a mobile phase of chloroform–methanol–acetone–formic acid (7.5 + 1.5 + 0.5 + 0.03, v/v) and a prewashed Silica Gel G60 F254 TLC plate as the stationary phase were used to resolve LST and HCTZ in a mixture. Two well-separated and sharp peaks for LST and HCTZ were obtained at Rf values of 0.61 ± 0.02 and 0.41 ± 0.02, respectively. LST and HCTZ were quantitated at 254.0 nm. The linearity ranges obtained for the HPTLC method are 400–1200 and 100–300 ng/spot with corresponding correlation coefficients of 0.9944 and 0.9979, for LST and HCTZ, respectively. Both methods were validated, and the results were compared statistically. They were found to be accurate, specific, and reproducible. The methods were successfully applied to the estimation of LST and HCTZ in combined tablet formulations.

This study explores the mechanical properties of an E-glass fabric composite reinforced with anchored multi-walled carbon nanotubes (CNTs). The CNTs were grown on the E-glass fabric using a floating catalyst chemical vapor deposition procedure. The E-glass fabric with attached CNTs was then incorporated into resin based composites and compared to similar composites without CNTs. Long and short beam bending tests, uniaxial compression measurements for energy dissipation, high strain-rate Split-Hopkinson pressure bar measurements, and ballistic performance (V50) tests were performed to characterize the mechanical properties of the CNT composites. The CNT composites showed a reduction in interlaminar shear strength by 25.9 %. They also showed an increase in the specific energy absorption by 106 % at high strain rates and an increase in energy density dissipation by 64.3 % after 5 cycles at quasi-static strain rates. In ballistic V50 tests, the CNT based composites showed a higher V50 value by 11.1 %. Due to their reduced weight and energy dissipation properties, the direct growth of CNTs on E-glass fabrics incorporated into composites have potential defense applications such as blast protection.

Building insulation materials have been subjected to various temperature and humidity conditions and their thermal performance during several weeks of controlled environmental exposure. Several commercially available insulation materials (three aerogel composite blankets, two extruded polystyrene foams (XPS) and one blown polyurethane foam (PUR)) were evaluated. The purpose is to compare performance of newer types (aerogel composites) with established types (foams). Thermal conductivity was measured with a heat flow metering apparatus at one week intervals for five weeks. Insulations were exposed to conditions of 65.6°C and 90% RH, 65.6°C and 60% RH, 65.6°C and 30% RH, and 32.2°C and 90% RH. Results indicate that humidity levels play a significant role in PUR performance, but not a significant role in XPS performance. The three aerogel composites have mixed results: one has little relationship between moisture content and thermal performance, one is strongly affected by moisture and the remaining is moderately affected by moisture. Fourier infrared spectrometry was performed on some of the materials to observe chemical stability. Results indicate that factors other than moisture content, such as hygroscopy and volume expansion, significantly contribute to thermal performance.

Thermal energy storage systems incorporated with phase change materials have potential applications to control energy use by building envelopes. However, it is essential to evaluate long-term performance of the phase change materials and cost-effectiveness prior to full-scale implementation. For this reason, we have used the accelerated long-term approach for studying the thermal performance and chemical stability of a commercially available bio-based phase change material during thermal cycling over a simulated period of 20 years. The phase change material was subjected to accelerate thermal aging under controlled environmental conditions. Small samples of the phase change material were periodically removed to measure its latent heat, thermal decomposition, and chemical stability using various analytical methods such as differential scanning calorimetry, thermogravimetry analysis, and infrared spectroscopy. The topographic changes in the phase change material due to the aging process were observed using scanning electron microscopy. The differential scanning calorimetry data indicate a significant reduction of 12% in the latent heat during heating and cooling cycles during the initial 6.2 years remain nearly constant thereafter. The thermogravimetry analysis results showed that the phase change material has excellent thermal stability within the working temperature range and also shows long-term decomposition temperature stability. The Fourier transform infrared spectra of the phase change material indicate absorption of moisture but the phase change material was chemically stable over the duration of accelerated aging cycles. After several aging cycles, the baseline surface morphology appeared to be changed from uniform mix of phase change material with microstructures to segregated microstructures as evidenced by the observation of the scanning electron micrographs.

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The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and polyurethane (PU) resin systems (FG/PE/VACNT and FG/PU/VACNT) are investigated and compared with the baseline materials, FG/PE and FG/PU (i.e., without VACNT). A Dynamic Mechanical Analyzer (DMA) was used for obtaining the mechanical properties. It was found that FG/PE/VACNT exhibited a significantly lower flexural stiffness at ambient temperature along with higher damping loss factor over the investigated temperature range compared to the baseline material FG/PE. For FG/PU/VACNT, a significant increase in flexural stiffness at ambient temperature along with a lower damping loss factor was observed with respect to the baseline material FG/PU. A Split Hopkinson Pressure Bar (SHPB) was used to evaluate the energy absorption and strength of specimens under high strain-rate compression loading. It was found that the specific energy absorption increased with VACNT layers embedded in both FG/PE and FG/PU. The compressive strength also increased with the addition of VACNT forest layers in FG/PU; however, it did not show an improvement for FG/PE.

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