Impact damage and CAI strength of a woven CFRP material with fire retardant properties

This paper presents the interrogation of low velocity impact and compression after impact test results on a woven fibre composite having a fire retardant, syntactic core, two phase epoxy matrix. The results of the study were to be utilized in a decision making process regarding the appropriateness of the material usage in question for a certain aerospace application. The epoxy matrix of the material system had dispersed black-pigmented particles with flame-retarding properties. Impact tests were performed at five impact energy levels. Two different laminate layup configurations were tested. Visual and C-Scan inspection were conducted, in order to observe the extent of the damage in the composite material. Compression tests were performed to study the residual strength after impact. Analytical formulation correlations with the test results presented opportunities for quantifying the interfacial fracture toughness resistance. Micro-graphs of the specimen's cross section were also produced in an effort to observe the fractured sections and characterise the various fracture mechanisms involved. The results exploitation in terms of design decision making are presented

Evaluation of cross-contamination of nylon bags with heavy loaded gasoline fire debris and with automotive paint thinner

Nylon bags are used for packaging fire debris in several countries, particularly in Europe. The possibility of cross-contamination during transport from the fire scene to the laboratory, in normal casework conditions in the UK, was studied for two brands of nylon bags, using simulated heavy loaded fire debris. Three experiments were carried out with each brand, using as sample a piece of cotton fabric soaked with gasoline. One experiment was carried out using automotive paint thinner (oxygenated solvent). Each sample was sealed in a nylon bag and stored in contact with eight empty bags. The empty bags were analysed at regular intervals for a period of time up to eight weeks, using SPME and GC/MS. Cross-contamination was found for components of gasoline (toluene and C2-alkylbenzenes) in the two brands of nylon bags used, after 4 days and 2 weeks. Cross contamination using automotive topcoat thinner was detected after 2 days

Predicting burst pressure of radiofrequency-induced colorectal anastomosis by bio-impedance measurement

The present study investigates the relationship between bio-impedance and burst pressure of colorectal anastomosis created by radiofrequency (RF)-induced tissue fusion. Colorectal anastomosis were created with ex-vivo porcine colorectal segments, during which 5 levels of compression pressure were applied by a custom-made bipolar prototype, with 5 replicate experiments at each compression pressure. Instant anastomotic tensile strength was assessed by burst pressure. Bio-impedance of fused tissue was measured by Impedance Analyzer across frequency that 100Hz to 3MHz. Statistical analysis shows only a weak correlation between bioimpedance modulus and burst pressures at frequency of 445 kHz (ρs= -0.426, P=0.099>0.05). In contrast, results demonstrated a highly significant negative correlation between reactance modulus and burst pressures (ρs= -0.812, P=0.000<0.05). The decrease in mean reactance modulus with increasing burst pressures was highly significant (p=0.019<0.05). The observed strong negative correlation between reactance modulus and burst pressures at frequency of 445 kHz indicates that reactance is likely to be a good index for tensile strength of RF-induced colorectal anastomosis, and should be considered for inclusion in a feedback loops in devices design

The effect of zinc on human taste perception

Zinc salts are added as a nutritional or functional ingredient in food and oral care products. The 1st experiment in this study investigated the taste and somatosensory effect of zinc salts (chloride, iodide, sulfate, bromide, acetate). The zinc salts had very little taste (bitter, salty, savory, sour, sweet), and the taste that was present was easily washed away with water rinses. The major oral quality of zinc was astringency, and the astringency lingered beyond expectoration. The 2nd experiment combined zinc salts with prototypical stimuli eliciting basic tastes. Zinc was a potent inhibitor of sweetness and bitterness (&gt;70% reduction in taste) but did not affect salt, savory, or sour taste.<br /

Flexural performance of innovative hybrid sandwich panels with special focus on the shear connection behavior

The present study intends to evaluate the flexural performance of hybrid sandwich panels through the execution of four point bending tests. The proposed hybrid sandwich panel uses Deflection Hardening Cementitious Composites (DHCC) on the top layer, a GFRP bottom layer and perforated shear connectors in the GFRP ribs to transfer shear stresses between top and bottom layers. The tested hybrid slabs use two types of shear connectors, which include indented and perforated shapes. The tests were performed to study the behaviour of a novel shear connection between the GFRP ribs and the DHCC layer that is here proposed. A comparison on the obtained experimental results was executed to clarify the influence of the shear connectors’ geometries on the flexural performance of the developed hybrid slabs. The results show that the shear connection mechanical behaviour strongly influences the peak load, the deflection at peak load, the post-peak load carrying capacity and the degree of composite action of the hybrid slabs.The study presented in this paper is a part of the research project "RehabGFRP - Rehabilitation of Building Floors with Lightweight High Performance GFRP Sandwich Panels", with reference number of PTDC/ECM/113041/2009. Furthermore, the authors honestly appreciate the collaboration of the following labs: Civitest for developing DHCC materials (Eng. Delfina Goncalves), PIEP for conducting VARTM process (Eng. Luis Oliveira) and Department of Civil Engineering of Minho University to perform the tests (Mr. Antonio Matos and Eng. Marco Jorge).info:eu-repo/semantics/publishedVersio

Assessment of MRI issues at 3-Tesla for metallic surgical implants: findings applied to 61 additional skin closure staples and vessel ligation clips

<p>Abstract</p> <p>Purpose</p> <p>Metallic skin closure staples and vessel ligation clips should be tested at 3-Tesla to characterize MRI issues in order to ensure patient safety. Therefore, metallic surgical implants were assessed at 3-Tesla for magnetic field interactions, MRI-related heating, and artifacts.</p> <p>Methods</p> <p>A skin closure staple (Visistat Skin Stapler, staple, Polytetrafluoroethylene, PTFE, coated 316L/316LVM stainless steel; Teleflex Medical, Durham, NC) and a vessel ligation clip (Hemoclip Traditional, stainless steel; Teleflex Medical, Durham, NC) that represented the largest metallic sizes made from materials with the highest magnetic susceptibilities (i.e., based on material information) among 61 other surgical implants (52 metallic implants, 9 nonmetallic implants) underwent evaluation for magnetic field interactions, MRI-related heating, and artifacts using standardized techniques. MRI-related heating was assessed by placing each implant in a gelled-saline-filled phantom with MRI performed using a transmit/receive RF body coil at an MR system reported, whole body averaged SAR of 2.9-W/kg for 15-min. Artifacts were characterized using T1-weighted, SE and GRE pulse sequences.</p> <p>Results</p> <p>Each surgical implant showed minor magnetic field interactions (20- and 27-degrees, which is acceptable from a safety consideration). Heating was not substantial (highest temperature change, ≤ 1.6°C). Artifacts may create issues if the area of interest is in the same area or close to the respective surgical implant.</p> <p>Conclusions</p> <p>The results demonstrated that it would be acceptable for patients with these metallic surgical implants to undergo MRI at 3-Tesla or less. Because of the materials and dimensions of the surgical implants that underwent testing, these findings pertain to 61 additional similar implants.</p

Castor Roots In A Vertic Inceptisol

The root systems of 4 large and 4 small, mature castor (Ricinus communis) cv. Acuna plants were excavated. Large and small plants had similar root:shoot ratios but roots of small plants were longer per unit weight. Soil factors in or near the surface of the C1 horizon, probably higher gravel and carbonate content, apparently restricted root penetration

Study of quantification methods in self-healing ceramics, polymers and concrete – a route towards commercialisation

During the past decades, research in self-healing materials has focused on the improvement in mechanical properties, making stronger materials, able to bear increasing solicitations. This strategy proved to be costly and in some cases inefficient, since materials continue to fail, and maintenance costs remained high. Instead of preparing stronger materials, it is more efficient to prepare them to heal themselves, reducing repairing costs and prolonging their lifetime. Several different self-healing strategies, applied to different material classes, have been comprehensively studied. When new materials are subject of research, the attention is directed into the formulations, product processing and scale-up possibilities. Efforts to measure self-healing properties have been conducted considering the specific characteristics of each material class. The development of comprehensive service conditions allowing an unified discussion across different materials classes and the standardization of the underlying quantification methods has not been a priority so far. Until recently, the quantification of self-healing ability or efficiency was focused mostly on the macroscale evaluation, while micro and nanoscale events, responsible for the first stage in material failure, received minor attention. This work reviews the main evaluation methods developed to assess self-healing and intends to establish a route for fundamental understanding of the healing phenomena