A new design of the iliac crest microsurgical free flap without including the "obligatory" muscle cuff

The iliac crest free flap has undergone a gradual evolution to provide more functional and cosmetic oromandibular reconstructions. The soft-tissue cutaneous component has largely resisted refinement and currently constitutes the flap's principal drawback. Conventionally, the cutaneous vessel's soft-tissue encasement and a protective cuff of abdominal muscle are harvested to ensure skin perfusion. These protective measures, however, produce a bulky flap that is tethered to the bone and difficult to inset into complex three-dimensional defects. A series of anatomic and clinical investigations has confirmed that in 30 percent of individuals, the skin island can be elevated on a dominant cutaneous branch from the deep circumflex iliac artery. Harvesting the skin as an axial pattern flap greatly increases its independence from the bone, improving maneuverability. A small collar of abdominal muscle is incised around the pedicle, obviating the need for the customary 2.5-cm protective muscle cuff. Exclusion of the abdominal muscular component reduces the flap's volume, decreases the need for secondary debulking, and reduces the donor site morbidity.     

A new flap from the dorsum of the first intermetacarpal area: the first dorsal intermetacarpal flap

Soft-tissue reconstruction of the hand still remains a challenge for plastic and reconstructive surgeons. Several flaps have been described to cover soft-tissue defects of the digits and the hand. In the first web region, there are some communications between the intermediate artery arising from the dorsal branch of the radial artery and the volar arteries of the thumb and the index finger. Depending on these communications, a new distally based flap is raised from the first dorsal intermetacarpal area. This flap has been used to cover various defects of the thumb in four patients and the distal radial side of the palmar area in one patient. Donor sites have been closed primarily except in one patient. There were no complications, and the results show that this flap is useful to cover soft-tissue defects of the thumb and proximal phalanx of the index finger as well as the radial side of the palmar and dorsal surfaces of the hand.     

Optimal channel reuse in cellular radio systems with multiplecorrelated log-normal interferers

The probability of co-channel interference (PCI) due to multiple correlated log-normal signals is calculated for cellular radio systems operating in Rayleigh fading and lognormal shadowing environment. The effects on the PCI of the correlation between the signals, the standard deviation due to shadowing, the number of interferers, the co-channel protection ratio, and the traffic load is investigated. The results are used for analyzing the optimal channel reuse, the cluster size, and the spectrum efficiency in terms of these parameters     

Multiple correlated log-normal interferers in mobile cellular radio systems

The probability of cochannel interference (PCI) is evaluated in shadowed mobile cellular systems considering multiple correlated log-normal interferers. The influence of blocking probability and the number of channels per cell on the performance is also presented. The effect of correlation on PCI is investigated for various values of the propagation path loss exponent.<>     

Determination of instantaneous breaking rate by Geological Strength Index, Block Punch Index and power of impact hammer for various rock mass conditions

In mining and construction industries, selection of appropriate excavation method and equipment significantly affects the project feasibility. In the selection, the most important parameters are the geomechanical properties of the rock mass in the excavation route as extensively reviewed in literature. The most widely used geomechanical parameter is uniaxial compressive strength (UCS). However, UCS laboratory test requires time consuming and expensive sampling and core sample preparation processes, which can be quite difficult or sometimes impossible for a weak rock material taken from foliated, laminated or thinly bedded rock masses of low Rock Quality Designation (RQD) values (0-20%). For these reasons, Block Punch Index (BPI) test, which has thus gained an importance for the last decade because of its simplicity, has become applicable to determine rock strength for highly-jointed and weak rocks of low RQD. BPI provides significant convenience particularly for laminated-foliated-anisotropic rocks. In this study, the excavability of various rocks with impact hammer was investigated using Geological Strength Index (GSI), power of impact hammer (P), BPI. Valuable results from which the users could benefit were obtained.     

Effect of Plasma Nitriding on the Performance of WC-Co Cutting Tools

This paper presents the effect of nitriding process parameters on the cutting performance of WC-Co tools. The cutting performance was measured by CNC machining of GG25 cast iron parts. The hardness and phase composition of nitrided layer were determined for different plasma nitriding temperatures and times. The hardness of the nitrided layer increased at all plasma nitrided conditions investigated. However, the machining performance of the cutting inserts varied in the range between a 60% increase and a 40% decrease after plasma nitriding. The maximum number of machined parts was seen when the insert was nitrided at 600 °C-4 h and at 500 °C-4 h.     

Hydrogen enriched waste oil biodiesel usage in compression ignition engine

In the present study, hydrogen enrichment for biodiesel-diesel blends was evaluated to investigate the performance and emission characteristics of a compression ignition engine. Biodiesel was obtained from waste oil and blended to pure diesel fuel by volume fraction of 0%, 10% and 20%. After that, pure hydrogen was introduced through the intake air at different flow rates. Effects of pure hydrogen on performance and emission characteristics were investigated by evaluating power, torque, specific fuel consumption, CO, CO₂ and NO_x emissions. Experimental study revealed that waste oil biodiesel usage deteriorated performance and emission parameters except CO emissions. However, the enrichment test fuels with hydrogen fuel can improve performance characteristics and emission parameters, whereas it increased NO_x emissions. Brake thermal efficiency and specific fuel consumption were improved when the test fuels enriched with hydrogen gas. Because of absence of carbon atoms in the chemical structure of the hydrogen fuel, hydrogen addition dropped CO and CO₂ emissions but increment in cylinder temperature caused rising in NO_x emissions.