Efficiency enhancement in low-bandgap polymer solar cells by processing with alkane dithiols

High charge-separation efficiency combined with the reduced fabrication costs associated with solution processing and the potential for implementation on flexible substrates make 'plastic' solar cells a compelling option for tomorrow's photovoltaics. Attempts to control the donor/acceptor morphology in bulk heterojunction materials as required for achieving high power-conversion efficiency have, however, met with limited success. By incorporating a few volume per cent of alkanedithiols in the solution used to spin-cast films comprising a low-bandgap polymer and a fullerene derivative, the power-conversion efficiency of photovoltaic cells (air-mass 1.5 global conditions) is increased from 2.8% to 5.5% through altering the bulk heterojunction morphology. This discovery can potentially enable morphological control in bulk heterojunction materials where thermal annealing is either undesirable or ineffective.

The pocket laser pointer as a teaching tool in laparoscopic surgery

The common pen-sized laser pointer can be used during laparoscopic procedures to indicate landmarks on the video screen and facilitate communication between surgeon and the assistants. We describe a simple and inexpensive technique that allows scrubbed members of the surgical team to use the laser pointer without the need to sterilize the instrument.

Pulmonary contusion: a collective review

Pulmonary contusion is the most common injury identified in blunt chest trauma. Despite improvements in diagnostic imaging and critical care, the associated mortality has not appreciably changed over the last three decades. Parenchymal injury ultimately manifests as alveolar collapse and lung consolidation. Early detection and intervention toward minimizing injury progression provides the greatest chance for survival. Avoiding fluid overload, oxygen therapy, and a low threshold for mechanical ventilation are useful therapeutic guidelines. Complications include pneumonia and adult respiratory distress syndrome, which may occur in up to one half of all cases. Pulmonary contusion is a serious injury that may complicate patient management as well as pose a vital threat.

Endoscopic jejunal access for enteral feeding

Enteral (gut) alimentation appears to offer greater benefit for patients than calories delivered via a parenteral (intravenous) route. Enteral alimentation prevents mucosal atrophy, maintains normal gut flora, decreases bacterial translocation, and enhances enteral immunological competence. Reliable delivery into the jejunum without the placement of an operative feeding tube is difficult, however. We have been interested for some time in endoscopically placing a jejunal tube for enteral nutrition early (within 24 hours) after trauma resuscitation or operation. A simplified technique is described for the endoscopic placement of a jejunal feeding tube, with or without a concomitant percutaneous endoscopic gastrostomy.

Weaning from mechanical ventilation

An understanding of respiratory physiology is helpful when weaning a patient from mechanical ventilation. Various criteria are available that assess pulmonary function and the patient's ability to breathe spontaneously. The majority of patients are weaned without difficulty, but a small percentage will require careful evaluation. A complete assessment of the patient is essential during the weaning trial. The mode of ventilation during weaning is less important than careful observation during the trial. Simple vital signs and physical findings remain some of the best indicators of success or failure.