Detection of cutaneous oxygen saturation using a novel snapshot hyperspectral camera: a feasibility study

Background: Tissue necrosis, a consequence of inadequate tissue oxygenation, is a common post-operative complication. As current surgical assessments are often limited to visual and tactile feedback, additional techniques that can aid in the interrogation of tissue viability are needed to improve patient outcomes. In this bi-institutional pilot study, the performance of a novel snapshot hyperspectral imaging camera to detect superficial cutaneous oxygen saturation (StO(2)) was evaluated.Methods: Healthy human volunteers were recruited at two participating centers. Cutaneous StO(2) of the forearm was determined by a snapshot hyperspectral camera on two separate study days during occlusionreperfusion of the brachial artery and after induction of local vasodilation. To calculate the blood StO(2) at each pixel in the multispectral image, spectra were selected, and fitting was performed over wavelengths ranging from 470 to 950 nm.Results: Quantitative detection of physiological changes in cutaneous StO(2) levels was feasible in all sixteen volunteers. A significant (P<0.001) decrease in cutaneous StO(2) levels from 78.3% (SD: 15.3) at baseline to 60.6% (SD: 19.8) at the end of occlusion phase was observed, although StO(2) levels returned to baseline after five minutes. Mean cutaneous StO(2) values were similar in the same subjects on separate study days (Pearson R2: 0.92 and 0.77, respectively) at both centers. Local vasodilation did not yield significant changes in cutaneous StO(2) values.Conclusions: This pilot study demonstrated the feasibility of a snapshot hyperspectral camera for detecting quantitative physiological changes in cutaneous StO(2) in normal human volunteers, and serves as a precursor for further validation in perioperative studies.Cardiovascular Aspects of Radiolog

A second mode of operating packed columns and wetted wall columns

For a fixed set of gas and liquid rates below the flooding flow rates in a wetted wall column and a packed column, two modes of operation are possible, viz., normal and incipient flooding. The latter has not been reported previously. Methods for stabilizing this mode of operation are described. Both modes can coexist in different sections of the same column. Modification to industrial packed towers to permit operation in the incipient flooding mode are simple and inexpensive. Such modifications permit operation with higher liquid holdup and higher mass transfer rates at the expense of higher pressure losses

Solids exchange between adjacent fluid beds without gas mixing

A new reactor system, in which two adjacent fluidized beds exchange solids but not gases, has been developed, and patented. The partition between the two fluidized beds is designed to permit the movement of solids in both directions, but to provide an effective seal against gas mixing. There are no moving parts. High circulation rates can be achieved, and can easily be controlled. Gas mixing at less than the 2% level can be achieved without a neutral blanketing gas to seal the interface. It should be possible to achieve zero leakage with a blanketing gas. The reactor system was developed as an oil shale retort in which the combustor exchanges solids with the retort - but in which the combustion gases and product gases are kept separate. However, the system has many potential applications including gasification and pyrolysis of coal, hydrogen production, heat exchange in difficult conditions and SO2 removal by absorption or adsorption

Circulating fluidized oil shale retort

A cold model of a twinned dense-phase circulating fluidized-bed system was investigated for use as a continuous oil shale retort. The twin beds permit continuous circulation of the shale and ash, which act as the heat carrier, while keeping the combustion gas and the retort product gases separate. This arrangement potentially has many process advantages. Experiments were conducted over a wide range of operating conditions. The results show that a high solids exchange rate can be achieved and easily controlled while the gas leakage between the compartments is kept satisfactorily low. The system provides very good operating flexibility. It also has a variety of other potential applications in e.g. catalytic reaction-regeneration, coal combustion-gasification and biomass combustion-pyrolysis

Adenoviral serotype 5 vectors pseudotyped with fibers from subgroup D show modified tropism in vitro and in vivo

Adenovirus (Ad5) serotype 5 vectors are commonly used for gene transfer. Preclinical studies have shown that their application to systemic gene delivery, however, is limited by their highly efficient uptake in the liver, principally mediated by receptor-binding sites on the fiber shaft and knob domain. Using Ad to target other sites in vivo requires vectors that lack hepatic tropism. We therefore sought to exploit Ad family diversity to isolate vectors that possessed poor hepatic tropism. We pseudotyped the fibers from Ad16 (subgroup B; Ad5/16), Ad19p (subgroup D; Ad5/19p), and Ad37 (subgroup D; Ad5/37) onto Ad5 capsids and assessed infectivity profiles in vitro in multiple cell types and in vivo in rats. In rat, mouse, and human hepatocytes, Ad5/19p and Ad5/37 both possessed a striking lack of hepatic cell infectivity compared with Ad5. Both vectors were, however, able to transduce human vascular endothelial and smooth muscle cells with efficiencies equal to or greater than that of nonmodified Ad5. We evaluated liver uptake in 12-week-old male rats after intravenous injection. In contrast to a vector with the wild-type Ad5 fiber, Ad5, both Ad5/19p and Ad5/37 produced significantly less virion accumulation (measured at 1 hr and 5 days) and transgene expression in the liver. Thus, Ad5/19p and Ad5/37 may be useful platforms for the development of targeted Ad vectors