Nickel- and copper-coated carbon fibre reinforced tin-lead alloy composites

Nickel and copper were deposited over brominated, surface treated, and pristine P-100 carbon fibres using cementation and electroplating techniques. The fibres were brominated by bromine vapour for 48 h and then desorbed at 200 °C in air for 12 h. The anodic oxidation treatment of the fibres involved electrochemical etching in a dilute sodium hydroxide electrolyte for 3 min. Electroplated coated fibres showed better tensile properties than cementation coated fibres. In addition, nickel coating exhibited better bonding with the carbon fibres compared to copper coating. The effect of bromination and surface treatment was improved adhesion between coating and fibres. Nickel- and copper-coated fibres, which were brominated, anodically oxidized, and pristine, reinforced tin-lead alloy composites were fabricated by squeeze casting. The composites containing coated treated carbon fibres had higher tensile and shear strength than the ones containing coated pristine carbon fibres. Moreover, the composite with coated brominated carbon fibres had better tensile strength and shear strength than the surface treatment. The results also showed the composites containing nickel-coated fibres had higher tensile and shear strength than the ones containing copper-coated fibres.     

The material properties of sulphonated phenolic resin reinforced cement mortars

The material properties of new sulphonated phenolic resin (SP) reinforced cement mortars have been investigated. SP was found to promote the dispersion of cement particles and to interact with Ca(OH)₂. As a result, the resulting mortars exhibit better workability, more compact structure and higher compressive strength than plain mortars. The mortar with 1 wt% SP present after 28 days curing exhibits a compressive strength of 66MPa, which is about 18% higher than that of plain mortar.     

Transurethral ultrasound array for prostate thermal therapy:initial studies

This study presents the initial evaluation of an applicator designed for transurethral ultrasound thermotherapy (TUST) of prostate tissue in the treatment of benign prostatic hyperplasia (BPH) and cancer. A tubular multitransducer applicator, consisting of four piezoceramic tubes (2.5 mm diameter, 6 mm long, 6.8 MHz) under separate power control, was designed to fit within a semiflexible water-cooled temperature-regulated delivery catheter to be placed within the prostatic urethra during therapy. Sonication patterns were tailored to produce power depositions which avoid nontargeted tissues, such as the rectum. Computer simulations have demonstrated that 1.4-2.0 cm radial therapeutic zones (temperatures ⩾50-55°C, thermal doses >300 EM₄₃) with concurrent sparing of the urethral mucosa can be produced within prostate tissue having blood perfusion as high as 10 kg m^-3 s^-1 within 15-30 min. Acoustic distributions and power output measurements of a prototype applicator have demonstrated acoustic power levels approaching 10 W per each sectored transducer segment are attainable, with beam profiles collimated within the transducer length and with desired circumferential distributions. In vivo thermal dosimetry characterizations of these transurethral applicators have indicated that therapeutic temperatures between 50 and 90°C are attainable, controllable in the longitudinal and circumferential directions, and have effective radial heating. These results clearly indicate that transurethral ultrasound applicators have potential to provide improved spatial localization and control of the heating distribution over existing transurethral thermal therapy techniques for both hyperthermia and thermal coagulative therapy of the prostate     

Antennas and other electromagnetic applicators in biology andmedicine

Medical and biological applications of antennas can be classified into two broad groups: (1) therapeutic and (2) informational (including diagnostics and measurement of material electromagnetic (EM) properties). Most of these applications involve EM coupling into or out of the body which requires a device such as an antenna or other applicator. A common characteristic of many applications is the difficulty of coupling EM energy into the interior of the body without damaging the surface. Rapidly increasing computing power and new developments in numerical EM techniques are expected to have a great impact on the use of EM devices in medicine and biology     

Analysis of slots in nonradiating dielectric waveguide using the modal expansion method

A modal expansion method is used with the reciprocity and Poynting theorems to derive the admittance of inclined slots cut in the metal wall of a nonradiating dielectric (NRD) waveguide. Theoretical values of normalised conductance and susceptance are compared with previously reported experimental results and are found to be in good agreement.<>     

Analysis of multichannel narrow-band filters for image texturesegmentation

A model for texture analysis and segmentation using multiple oriented channel filters is analyzed in the general framework. Several different arguments are applied leading to the conclusion that the two-dimensional Gabor filters possess strong optimality properties for this task. Properties of the multiple-channel segmentation approach are analyzed. In particular, perturbations of textures from an ideal model are found to have important effects on the segmentation that can usually be ameliorated by simply preceding the segmentation process by a logarithmic operation and using a low-pass postfilter prior to making region assignments. The difficult problems of space-variant textures and multiple component textures are also considered. Local spatial frequency estimation approaches are suggested that use the responses as constraints in estimating the locally emergent texture frequencies. Complex texture aggregates containing multiple shared frequency components can be analyzed if the textures are distinct and few in number     

The influence of cathodic hydrogen charging on the mechanical behaviour of Al-4Zn-1Mg alloy

The effect of cathodic charging on the mechanical behaviour of Al-4Zn-1Mg alloy was studied. Hardening of the Al-4Zn-1Mg alloy surface, due to the hydrogen absorption, was observed. The ultimate tensile stress of the charged aluminium alloy was noted to be a non-linear function of the charging current density. The cathodically charged aluminium alloy exhibited brittle transgranular fracture at the surface layer, whereas ductile intergranular fracture was observed at the deeper layers of the same alloy.