In this work, the aim was to coprocess and evaluate a new cellulose-based direct compression tableting excipient (MCR) of improved functionalities by granulation and slugging from locally extracted microcrystalline cellulose and regenerated cellulose (CRC). Materials and Methods: Model tablet formulations of metronidazole (MZ) as a model of nonfreely flowing and directly incompressible active pharmaceutical ingredient were designed to study the tableting properties of MCR. Results: The results showed that the optimum concentration of CRC needed to produce excipient of accepted flow properties and high compression characteristics was 20% w/w. MCR performed better than the parent components either singly or in a simple binary mixture. MZ tablets of enhanced mechanical properties and fast disintegrating and dissolving rates were compressed from MCR. The crushing strength (H) and the disintegration rate constant (k d) increased from 3.76 to 11.08 kg and from 0.92 to 13.1×10-3 s-1 for the tablets made with 50% w/w MCR, respectively. Conclusion: Both the H and k d values of a given MZ tablet batch were found to be functions of the total number of bonding sites (α) available in the excipient in the given batch. MCR was unfortunately sensitive to magnesium stearate. The obtained result revealed that MCR is a successful complementary direct compression excipient.
One possible method for strengthening deteriorated concrete structures is to externally bond composite material plates to the concrete. The use of Carbon Fiber Reinforced Polymer (CFRP) laminates as an effective and versatile technique for strengthening reinforced concrete (RC) structures has developed into a sizable industry in recent years. To implement such rehabilitation, the nature of the bond between the composite plate and the concrete must be understood. The behavior of reinforced concrete beams strengthened in the negative moment region using CFRP strips is presented in this paper. The experimental program included strengthening and testing five half-scale, reinforced, simply supported rectangular cross section beams with an overhanging (cantilever) portion. One of the tested specimens was tested without any strengthening and considered as the control specimen. The rest specimens were strengthened with CFRP strips using different technique and then tested until complete failure. The effect of strengthening technique on deflection, failure load, strain, failure mode, and ductility are discussed. In addition, and due to local stress concentration at the plate ends, the influence of different type of CFRP fixation at both ends for proper bonding of the strips, and the strengthening pattern on the behavior of beams was examined. The ratio of absorbed energy at failure to total energy, or energy ratio, was used as a measure of beam ductility. The results generally indicate that the flexural strength of the strengthened beams is increased. It is also noted that, in addition to the longitudinal CFRP plates, the fiber oriented in the vertical direction forming a C or U-shape around the beam cross section significantly reduce beam deflections and increase beam load carrying capacity. However, all the strengthened beams experienced semi brittle failure, mandating a higher factor of safety in design. The results also indicate that plating reduced crack size in the beams and somewhat reduced their ductility.
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