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Effects of through-the-thickness stitching on the impact damage resistance, impact damage tolerance, and interlaminar fracture toughness (Mode I and Mode II) of plain woven and uniweave textile graphite/epoxy laminates were investigated. The uniweave textile was formed by weaving dry carbon-fiber tows with fiberglass fill tows. The content of fiberglass fill tows was 2.5% by weight. The plain woven laminates were manufactured using resin infusion molding and the uniweave laminates by resin transfer molding. Kevlar and glass yarns of various yarn numbers were used for stitching. Static Indentation-Flexure, Compression-After-Impact, Double Cantilever Beam and End-Notched Flexure tests were conducted. Stitching did not have any effect on the onset of impact damage. However, stitching leads to significant improvement (25-40%) in impact damage tolerance as measured by CAI strength and impact damage area. Mode I fracture toughness as characterized by critical strain energy release rate (G,Ic) was found to increase by at least an order higher (15-30 times) than the unstitched laminates. Mode II fracture toughness (GIIc) increased by 5-15 times over the unstitched laminates. New methods to estimate the Mode II critical strain energy release rate in the stitched laminates are presented. The stitched textile advanced composites are considered potentially superior to prepregs for high-volume, low-cost and high-performance structural materials.

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Apparent molar volumes (V ⌀ ), apparent molar isentropic compression (K ⌀,s ), and viscosity B coefficient of glycine, L-alanine, and L-valine in (0.01 and 0.03) mol·kg −1 aqueous tetrabutyl ammonium iodide (TBAI) solutions have been determined at temperatures (288.15, 293.15, 298.15, 303.15, and 308.15) K from their experimental density, ultrasonic speed, and flow time measurements, respectively. Partial molar volumes (V ⌀ 0 ) and partial molar isentropic compression (K ⌀,s 0 ) have been determined from the above measurements. Further, these data were used to calculate the corresponding transfer parameters (ΔV ⌀,s 0 and ΔK ⌀,s 0 ), hydration number (n H ), side chain group contributions of V ⌀ 0 , and viscosity B coefficients of the amino acids, partial molar expansibilities (E ⌀ 0 ), (dB/dT), and related parameters. The trends of variations of experimental and computed parameters have been discussed in terms of solute−solvent interactions with an emphasis on structure-making and structure-breaking ability of the above amino acids in the solvent mixture.

The pharmacokinetics and dosage regimen of ceftriaxone were investigated in buffalo calves (n = 6) following a single intravenous administration of ceftriaxone (10 mg/kg). The elimination rate constant was 0.18 +/- 0.01 h(-1) and the elimination half-life was 3.79 +/- 0.09 h. The apparent volume of distribution (Vd(area)) was 1.40 +/- 0.01 L/kg and the total plasma clearance was 0.26 +/- 0.01 L/(kg h). Approximately 43% of total administered dose of ceftriaxone was excreted in urine within 8 h. To maintain a minimum therapeutic concentration of 1 microg/ml, a satisfactory intravenous dosage regimen of ceftriaxone in buffalo calves is 13 mg/kg repeated at 12 h intervals.