Necrotizing fasciitis of the face

Necrotizing fasciitis (NF) is a rapidly progressive soft tissue infection with high morbidity and mortality rates. Its occurrence in the head and neck region is uncommon, the majority of reported cases being limited to involvement of the neck, usually from infections of dental or pharyngeal origin. Involvement of the face from NF is rare; only 35 such cases have been reported in the literature since 1960. It is not only associated with a high mortality but can also result in severe disfigurement of the face, posing challenging reconstructive problems. Successful management of facial NF requires early diagnosis, prompt institution of broad spectrum antibiotics, aggressive surgical debridement to control the infection, and reconstruction of the resultant soft tissue defects. This report describes four additional cases of facial necrotizing fasciitis. One of the four patients died as a result of sepsis and multi-organ system failure. Two of the three surviving patients had significant facial disfigurement. A comprehensive review of the facial NF cases reported in the literature is also provided. Based on our experience with facial NF and the results of all previous case reports, the clinical manifestations, pathogenesis, and management of this disease are discussed.     

Preparation of niobates of rhodium and nickel and their catalytic behaviors during calcination and reduction treatments

Double oxides of Rh and Ni have been prepared by chemical mixing methods. Silica-supported and unsupported RhNbO₄ and NiNb₂O₆ catalysts exhibited strong metal-oxide interaction behaviors in ethane hydrogenolysis activities after the decomposition of the double oxides by H₂ reduction at 500°C. Silica-supported and zeolite-supported RhVO₄ catalysts showed high activity and selectivity for dehydrogenation of cyclohexane after the decomposition in H₂. The double-oxide catalyst systems can be used as starting materials to obtain high-performance metal catalysts (redispersion of metals by H₂ reduction and regeneration of catalysts by calcination at a high temperature).     

Network formation and swelling behavior of photosensitive poly(vinyl alcohol) gels prepared by photogenerated crosslinking

Poly (vinyl alcohol) with pendent styrylpyridinium groups (SbQ) is insolubilized by photoirradiation. An association takes place in SbQ groups. The association of polymer chains becomes marked with increasing the number of SbQ groups. Mainly intermolecular crosslinks were formed. Transparent and homogeneous macrogels consisting of several intermolecular crosslinks are obtained. The proportion of the free water to the bound water in PVA-SbQ gels was 3.3?2.9 despite of the large change in conversion of photodimerization of SbQ groups, x=0.27?0.58. The water uptake after swelling of the gels in water increased 6–27 times compared to the original weight at pH=7. The higher the degree of photocrosslinking, the lower was the degree of swelling. The water diffusion coefficients, D, were (2.2?5.8) × 10^?5 cm² S^?1 for a 88% saponified PVA with 1 . 3 mol% SbQ groups. The volume of the gel increased discontinuously about 10-fold for the 99% saponified PVA with 0 . 096 mol% SbQ and 51% water (49% acetone). The acetone concentration at the transition decreased with increasing the degree of saponification of the PVA.     

On the dehydrogenation reaction of n-butane with the deactivation of alumina-chromia catalyst

An experimental study on the dehydrogenation reaction of n-butane to n-butene with alumina-chromia catalyst has been performed using a differential reactor. N-butene produced and coke deposit on the catalyst were continuously measured and the mechanisms of the reactions of dehydrogenation of n-butane and coke deposition have been investigated. According to the assumptions that there are two types of active sites effective for the dehydrogenation reaction, Lewis acid site and Brönsted acid site, and that the coke deposition takes place only at Lewis acid sites, the rate equations of these reactions have been obtained.     

Orientation structure in transverse sections of carbon fibers from dehydrated polyvinyl alcohol

Transverse sections of carbon fibers prepared from two different lots of dehydrated polyvinyl alcohol fibers, with and without graphitizing treatment, were observed by both polarized light and scanning electron microscopy. Several different types of transverse layer plane preferred orientation were found in the graphitized fibers: layers aligned parallel with the section major axis in the central zone of elliptical cross sections; parallel with the fiber surface in concave regions of an irregular cross section shape; and parallel with the fiber surface in a highly crystallized fiber with an irregular cross section shape. These graphitic layer plane configurations are considered in connection with the lamellar structure in crystalline regions of the dehydrated polyvinyl alcohol fibers.     

Deformation behaviour of elastic-plastic tubes under external pressure and axial load

A constitutive equation taking into account corner formation on the yield surface and the Bauschinger effect is developed. The behaviour of circular long tubes subjected to external pressure and axial load under plane strain and generalized plane-strain conditions are analyzed in conjunction with the proposed constitutive equation. The influence of axial load, the Bauschinger effect and corner formation, including the corner angle, and the mobility of the corner axis to the direction of stress history upon such global deformation behaviour as maximum pressure, pressure vs displacement relation and axial strain, are clarified. With regard to local deformation, these effects on the strain rate and strain localization, surface unevenness and shear band formation from the highly strained internal surface are investigated.     

Rayleigh waves in magneto-thermoelastic solids with thermal relaxation

Following a linear theory of magneto-thermo-elasticity with thermal relaxation, the propagation of Rayleigh waves in a semi-infinite body permeated by an uniform magnetostatic field parallel to the boundary surface is investigated. It is assumed that the elastic medium under consideration is a homogeneous, isotropic, electrically and thermally conducting one. The roots of the frequency equation are calculated numerically. The approximate solution for small thermoelastic and magnetoelastic coupling is obtained and compared with the exact solution.     

The interface crack problem for bonded piezoelectric and orthotropic layers under antiplane shear loading

The primary objective of this paper is to study the influence of the electroelastic interactions on the stress intensity factor in bonded layers of piezoelectric and orthotropic materials containing a crack along the interface under antiplane shear. Attention is given to a two-layer hybrid laminate formed by adding a layer of piezoelectric ceramic to a unidirectional graphite/epoxy composite or an aluminum layer. Electric displacement or electric field is prescribed on the surfaces of the piezoelectric layer. The problem is formulated in terms of a singular integral equation which is solved by using a relatively simple and efficient technique. A number of examples are given for various material combinations. The results show that the effect of the electroelastic interactions on the stress intensity factor and the energy release rate can be highly significant. This revised version was published online in July 2006 with corrections to the Cover Date.