The tensile properties of weft-knitted biaxial tubular fabrics and reinforced composites

Weft-knitted biaxial tubular (WKBT) fabrics have been infiltrated via a resin film infusion technique to fabricate reinforced composites. To understand the mechanical properties of WKBT fabrics and the reinforced composites, the strength efficiency of insertion yarns and insertion fiber volume fraction are used to evaluate the tensile strength. The tensile properties of WKBT fabrics and the reinforced composites are studied in the 0° and 90° directions. The results show that both have two failure stages. The first stage is the fracture of insertion yarns which provide the main tensile strength, and the second stage is the fracture of stitch yarns which have significant effect on the tensile strength of WKBT fabrics and the reinforced composites. It is observed that the deformation behavior and failure mechanism of WKBT fabric reinforced composites are closely related to the structure of WKBT fabric, which can be used to predict the failure mode and morphology of WKBT fabric reinforced composites.

Design, Development, and Characterization of Advanced Textile Structural Hollow Composites

The research is focused on the design and development of woven textile-based structural hollow composites. E-Glass and high tenacity polyester multifilament yarns were used to produce various woven constructions. Yarn produced from cotton shoddy (fibers extracted from waste textiles) was used to develop hybrid preforms. In this study, unidirectional (UD), two-dimensional (2D), and three-dimensional (3D) fabric preforms were designed and developed. Further, 3D woven spacer fabric preforms with single-layer woven cross-links having four different geometrical shapes were produced. The performance of the woven cross-linked spacer structure was compared with the sandwich structure connected with the core pile yarns (SPY). Furthermore, three different types of cotton shoddy yarn-based fabric structures were developed. The first is unidirectional (UD), the second is 2D all-waste cotton fabric, and the third is a 2D hybrid fabric with waste cotton yarn in the warp and glass multifilament yarn in the weft. The UD, 2D, and 3D woven fabric-reinforced composites were produced using the vacuum-assisted resin infusion technique. The spacer woven structures were converted to composites by inserting wooden blocks with an appropriate size and wrapped with a Teflon sheet into the hollow space before resin application. A vacuum-assisted resin infusion technique was used to produce spacer woven composites. While changing the reinforcement from chopped fibers to 3D fabric, its modulus and ductility increase substantially. It was established that the number of crossover points in the weave structures offered excellent association with the impact energy absorption and formability behavior, which are important for many applications including automobiles, wind energy, marine and aerospace. Mechanical characterization of honeycomb composites with different cell sizes, opening angles and wall lengths revealed that the specific compression energy is higher for regular honeycomb structures with smaller cell sizes and a higher number of layers, keeping constant thickness.

Comparison of a metronome-guided prehospital medication infusion technique with standard calculation: a simulated randomized, controlled, cross-over study

Background Limited research regarding administration of timed medication infusions in the prehospital environment has identified wide variability with accuracy, timing, and overall feasibility. This study was a quality improvement project that utilized a randomized, controlled, crossover study design to compare two different educational techniques for medication infusion administration. We hypothesized that the use of a metronome-based technique would decrease medication dosage errors and reduce time to administration for intravenous medication infusions. Methods Forty-two nationally registered paramedics were randomized to either a metronome-based technique versus a standard stopwatch-based technique. Each subject served as a control. Subjects were asked to establish an infusion of amiodarone at a dose of 150 mg administered over 10 min, simulating treatment of a hemodynamically stable patient with sustained monomorphic ventricular tachycardia. Descriptive statistics and a repeated measures mixed linear regression model were used for data analysis. Results When compared to a standard stopwatch-based technique, a metronome-based technique was associated with faster time to goal (median 34 s [IQR, 22–54] vs 50 s; [IQR 38–61 s], P = 0.006) and fewer mid-infusion adjustments. Ease of use was reported to be significantly higher for the metronome group (median ranking 5, IQR 4–5) compared to the standard group (median ranking 2, IQR 2–3; P < 0.001). Conclusions Knowledge regarding a metronome technique may help EMS clinicians provide safe and effective IV infusions. Such a technique may be beneficial for learners and educators alike.

Energy: Protein Ratio in Ruminants: Insights from the Intragastric Infusion Technique

Studies on energy:protein ratio in ruminants are constrained by rumen fermentation since it governs nutrient metabolism and the ratio of energy:protein yielding nutrients available for absorption. By circumventing rumen fermentation, the total intragastric infusion technique (IIT) allowed objective quantification of maintenance energy and protein requirements, volatile fatty acid utilisation efficiency, efficiency of energy utilisation for maintenance (Km) and growth (Kf) and the origin of N retention responses to independent variation of energy and protein intake. This review outlines the key IIT findings and whether they are reflected in current feeding systems with implications for different production systems worldwide. Maintenance energy requirements are similar to those derived from comparative slaughter but maintenance N requirements are significantly lower. No differences in utilisation efficiency exist between acetic, propionic and butyric acids. At low energy intakes, endogenous energy reserves are utilised to retain amino acids and fuel substantial tissue protein gains. The use of fasting metabolism to measure the utilisation of nutritionally balanced diets is questioned since it is a glucose-deficient state. Inter-species differences in glucose metabolism appear to exist, suggesting that glucose requirements may be higher in cattle than sheep. The difficulty in predicting nutrient requirements, particularly protein, with any one technique is highlighted.

Comparison of a Metronome-guided Prehospital Medication Infusion Technique with Manual Calculation: A Simulated Randomized, Controlled, Cross-over Study

BackgroundLimited research regarding administration of timed medication infusions in the prehospital environment has identified wide variability with accuracy, timing, and overall feasibility. This study was a pragmatic, randomized, controlled, crossover study comparing two different techniques for medication infusion administration. We hypothesized that the use of a metronome-based technique would decrease medication dosage errors and reduce time to administration for intravenous medication infusions. Methods Forty-two nationally registered paramedics were randomized to either a metronome-based technique versus a standard stopwatch-based technique. Each subject served as a control. Subjects were asked to establish an infusion of amiodarone at a dose of 150 mg administered over 10 minutes, simulating treatment of a hemodynamically stable patient with sustained monomorphic ventricular tachycardia. Descriptive statistics and multiple linear regression were used for data analysis. Results When compared to a standard stopwatch-based technique, a metronome-based technique was associated with faster time to goal, fewer mid-infusion adjustments, and greater ease of use. Conclusions Use of a metronome technique for establishing medication infusion rates may help prehospital clinicians provide safer and more precise medication delivery.

The Effect of Stacking Sequence and Ply Orientation on the Mechanical Properties of Pineapple Leaf Fibre (PALF)/Carbon Hybrid Laminate Composites

In this paper, the effects of stacking sequence and ply orientation on the mechanical properties of pineapple leaf fibre (PALF)/carbon hybrid laminate composites were investigated. The hybrid laminates were fabricated using a vacuum infusion technique in which the stacking sequences and ply orientations were varied, which were divided into the categories of cross-ply symmetric, angle-ply symmetric, and symmetric quasi-isotropic. The results of tensile and flexural tests showed that the laminate with interior carbon plies and ply orientation [0°, 90°] exhibited the highest tensile strength (187.67 MPa) and modulus (5.23 GPa). However, the highest flexural strength (289.46 MPa) and modulus (4.82 GPa) were recorded for the laminate with exterior carbon plies and the same ply orientation. The fracture behaviour of the laminates was determined by using scanning electron microscopy, and the results showed that failure usually initiated at the weakest PALF layer. The failure modes included fibre pull-out, fibre breaking, matrix crack, debonding, and delamination.

Sedative and analgesic potentials of dexmedetomidine gluconate using constant rate infusion technique in rabbit

Rabbits are easily stressed. Stress can be caused by pain, disease, unfamiliar surroundings, transport, rough handling or proximity of potential predators. Thus, this study was conceived to evaluate the effective sedative and analgesic doses of dexmedetomide gluconate in rabbits using the constant rate infusion (CRI) technique. Eight healthy adult New Zealand White rabbits with an average weight of 1.93 ± 0.33kg were used for the study. They were starved of feed for three hours before the experiment but were supplied water sufficiently. The CRI infusion was prepared by adding 1mcgkg-1 into 500mL bags of lactated ringer's solution. Each rabbit received an initial dose of 20mcgkg-1 dexmedetomidine® intramuscularly at the thigh muscle. Venous access was secured fifteen minutes later and the fluid prepared for CRI was connected to the cannular, the fluid was set to flow at daily fluid maintenance rate of 90mlkgday-1 for one hour. The procedure was repeated replacing 20mcgkg-1 with 40mcgkg-1. Neither sedation nor analgesia was achieved with 20mcgkg-1 dexmedetomidine® while 40mcgkg-1 gave mild to moderate sedation, however, no analgesic effect was observed with the two dose regimes. In conclusion, sedation was achieved with 40mcgkg-1 but no analgesic effect was achieved in both doses used.