The past several decades have seen a significant rise in atmospheric carbon dioxide levels resulting from the combustion of hydrocarbon fuels. A solar energy based technology to recycle carbon dioxide into readily transportable hydrocarbon fuel (i.e., a solar fuel) would help reduce atmospheric CO2 levels and partly fulfill energy demands within the present hydrocarbon based fuel infrastructure. We review the present status of carbon dioxide conversion techniques, with particular attention to a recently developed photocatalytic process to convert carbon dioxide and water vapor into hydrocarbon fuels using sunlight.

Highly ordered vertically oriented TiO(2) nanotube arrays fabricated by electrochemical anodization offer a large surface area architecture with precisely controllable nanoscale features. These nanotubes have shown remarkable properties in a variety of applications including, for example, their use as hydrogen sensors, in the photoelectrochemical generation of hydrogen, dye-sensitized and solid-state heterojunction solar cells, photocatalytic reduction of carbon dioxide into hydrocarbons, and as a novel drug delivery platform. Herein we consider the development of the various nanotube array synthesis techniques, different applications of the TiO(2) nanotube arrays, unresolved issues, and possible future research directions.

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Sepsis and hemorrhage can result in injury to multiple organs and is associated with an extremely high rate of mortality. We hypothesized that peritoneal negative pressure therapy (NPT) would reduce systemic inflammation and organ damage. Pigs (n = 12) were anesthetized and surgically instrumented for hemodynamic monitoring. Through a laparotomy, the superior mesenteric artery was clamped for 30 min. Feces was mixed with blood to form a fecal clot that was placed into the peritoneum, and the abdomen was closed. All subjects were treated with standard isotonic fluid resuscitation, wide spectrum antibiotics, and mechanical ventilation, and were monitored for 48 h. Animals were separated into two groups 12 h (T12) after injury: for NPT (n = 6), an abdominal wound vacuum dressing was placed in the laparotomy, and negative pressure (-125 mmHg) was applied (T12 - T48), whereas passive drainage (n = 6) was identical to the NPT group except the abdomen was allowed to passively drain. Negative pressure therapy removed a significantly greater volume of ascites (860 ± 134 mL) than did passive drainage (88 ± 56 mL). Systemic inflammation (e.g. TNF-α, IL-1β, IL-6) was significantly reduced in the NPT group and was associated with significant improvement in intestine, lung, kidney, and liver histopathology. Our data suggest NPT efficacy is partially due to an attenuation of peritoneal inflammation by the removal of ascites. However, the exact mechanism needs further elucidation. The clinical implication of this study is that sepsis/trauma can result in an inflammatory ascites that may perpetuate organ injury; removal of the ascites can break the cycle and reduce organ damage.

Systematic review, level IV.

BACKGROUND Improper mechanical ventilation can exacerbate acute lung damage causing a secondary ventilator induced lung injury (VILI). We hypothesize that VILI can be reduced by modifying specific components of the ventilation waveform (mechanical breath) and studied the impact of airway pressure release ventilation (APRV) and controlled mandatory ventilation (CMV) on the lung micro-anatomy (alveoli and conducting airways). The distribution of gas during inspiration and expiration and the strain generated during mechanical ventilation in the micro-anatomy (micro-strain) were calculated. STUDY DESIGN Rats were anesthetized, surgically prepared and randomized into one uninjured Control group (n=2) and four groups with lung injury: 1)APRV 75% (n=2)–time at expiration (TLow) set to terminate appropriately at 75% of Peak Expiratory Flow Rate (PEFR); 2)APRV 10% (n=2)-TLow set to terminate inappropriately at 10% of PEFR; 3)CMV with PEEP 5cmH2O (PEEP 5;n=2) or 4)PEEP 16cmH2O (PEEP 16;n=2). Lung injury was induced in the experimental groups by Tween lavage and ventilated with their respective settings. Lungs were fixed at peak inspiration and end expiration for standard histology. Conducting airway and alveolar air space areas were quantified and conducting airway micro-strain calculated. RESULTS All lung injury groups redistributed inspired gas away from alveoli into the conducting airways. APRV 75% minimized gas redistribution and micro-strain in the conducting airways and provided the alveolar air space occupancy most similar to Control at both inspiration and expiration. CONCLUSIONS In an injured lung, APRV 75% maintained micro-anatomical gas distribution similar to that of the normal lung. The lung protection demonstrated in previous studies using APRV 75% may be due to a more homogeneous distribution of gas at the micro-anatomical level as well as a reduction in conducting airway micro-strain.

Continuous mandatory ventilation in normal rats for 6 hours with Vt and PEEP settings similar to those of surgery patients caused ALI. Preemptive application of APRV blocked early drivers of lung injury, preventing ARDS. Our data suggest that APRV applied early could reduce the incidence of ARDS in patients at risk.

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