Interaction of SH guided waves with wall thinning

This paper investigates through experiment and finite element modelling, the interaction and mode conversion phenomenon of SH0 and SH1 guided wave modes on a metal plate with machined wall thinning. Quantitative analysis was performed by calculating the reflection and transmission coefficients at the leading and trailing linearly tapered edges, for incident SH0 and SH1 modes. Several geometries were evaluated by varying the taper length and depth. Experiments were performed with periodic permanent magnet array EMATs as transmitters and receivers, generating a single SH mode, whilst both SH0 and SH1 are received. Experimental and numerical data show good agreement, revealing that the interaction of SH guided waves with such defects is complex when mode conversion arises. The values of the reflection and transmission coefficients are non-monotonic along the thinning depth and edge angle ranges. The quantitative results provide insight into the capabilities and limitations of guided SH wave measurements for simple corrosion type defects, indicating that with current capabilities, inspection of real defects will be limited to screening type measurements rather than detailed quantification of the defect region

Precision crop load management part 2.

The Precision Crop Load management protocol, which was used by some growers in 2013, consisted of first defining the optimum fruit number/tree (target fruit number) and then pruning to reduce flower bud numbers to 1.5 times the target fruit number. Chemical thinning consists of applying sequential thinning sprays (with rates and timing guided by the carbohydrate balance model and the fruit growth rate model to assess thinning efficacy). The program was successful in guiding chemical thinning decisions in 2013

Structural basis for membrane insertion by the human ER membrane protein complex

A defining step in the biogenesis of a membrane protein is the insertion of its hydrophobic transmembrane helices into the lipid bilayer. The nine-subunit endoplasmic reticulum (ER) membrane protein complex (EMC) is a conserved co- and posttranslational insertase at the ER. We determined the structure of the human EMC in a lipid nanodisc to an overall resolution of 3.4 angstroms by cryo–electron microscopy, permitting building of a nearly complete atomic model. We used structure-guided mutagenesis to demonstrate that substrate insertion requires a methionine-rich cytosolic loop and occurs via an enclosed hydrophilic vestibule within the membrane formed by the subunits EMC3 and EMC6. We propose that the EMC uses local membrane thinning and a positively charged patch to decrease the energetic barrier for insertion into the bilayer

Waveguiding in planar photonic crystals

Photonic crystal planar circuits designed and fabricated in silicon on silicon dioxide are demonstrated. Our structures are based on two-dimensional confinement by photonic crystals in the plane of propagation, and total internal reflection to achieve confinement in the third dimension. These circuits are shown to guide light at 1550 nm around sharp corners where the radius of curvature is similar to the wavelength of light

Customized pachymetric guided epithelial debridement for corneal collagen cross linking

<p>Abstract</p> <p>Backround</p> <p>We describe a modified method for deepitheliazation prior to corneal cross linking (CXL). The technique may overcome the current corneal pachymetric limitation parameter (over 400 microns) that is necessary for the safety of the procedure without affecting the overall benefits.</p> <p>Methods</p> <p>In a series of two patients, with inferior topographic steepening and regional thinning (less than 400 microns corresponding to the area of corneal steepening), CXL after customized epithelial removal was performed.</p> <p>Results</p> <p>There were no intra- or postoperative adverse events seen by the nine month follow up examination. Stabilization of the corneal ectasia was observed up to nine months post-costumized pachymetric-guided epithelial removal.</p> <p>Conclusion</p> <p>The technique of customized pachymetric-guided epithelial removal is easy to perform and may overcome the limitations of the preoperative corneal pachymetry expanding the application of the procedure in patients with regional corneal thinning.</p

Corneal stromal demarcation line after collagen cross-linking in corneal ectatic diseases: a review of the literature

Collagen cross-linking (CXL) is a relatively new conservative approach for progressive corneal ectasia, which is able to strengthen corneal tissue reforming new covalent bonds. Subjective and objective results following this method seem to be promising. In recent years, newer CXL protocols have been developed to perform more effective and less invasive procedures. The increasing diffusion of CXL in the corneal ectatic disease has increased the need to have actual indices regarding the efficacy of the treatment. Evaluation of demarcation line (DL), a transition zone between the cross-linked anterior corneal stroma and the untreated posterior corneal stroma, is considered a measurement of the depth of CXL treatment into the stroma. Some evidence in the literature emphasize that DL could be a measure of effectiveness of the CXL. On the contrary, some authors believe that the "the deeper, the better" principle is rather a simplistic approach for interpreting the clinical importance of the corneal stromal DL

Solution heat treatment, forming and in-die quenching of a commercial sheet magnesium alloy into a complex-shaped component: experimentation and FE analysis

Interest in lightweight materials, particularly magnesium alloys, has increased significantly with rising efficiency requirements in the automotive sector. Magnesium is the lightest available structural metal, with a density approximately 35% lower than that of aluminium. The potential is great for magnesium to become a primary material used in future low carbon vehicle structures; however, there are significant obstacles, namely low ductility and formability, particularly at room temperature. The aim of this work is to present the feasibility of using the solution Heat treatment, Forming, and in-die Quenching (HFQ) process to produce complex shapes from a sheet magnesium alloy, and to use the results to verify a simulation of the process developed using commercial FE software. Uniaxial tensile tests were initially conducted to establish the optimum parameters for forming the part. Stamping trials were then carried out using these parameters, and a simulation set up modelling the forming operation. It was shown that the HFQ process could be used to form a successful component from this alloy, and that a good match was achieved between the results of the forming experiments and the simulation.The authors gratefully acknowledge the support from the EPSRC (Grant Ref: EP/I038616/1) for TARF-LCV: Towards Affordable, Closed-Loop Recyclable Future Low Carbon Vehicle Structures