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March 8, 2012

Research Notes

Gold nanoparticles detect gas

Pitt researchers have coaxed gold into nanowires as a way of creating an inexpensive material for detecting poisonous gases found in natural gas.

Principal investigator Alexander Star of chemistry, with colleagues at the National Energy Technology Laboratory (NETL), developed a self-assembly method that uses scaffolds to grow gold nanowires.

Their results, “Welding of Gold Nanoparticles on Graphitic Templates for Chemical Sensing,” were published online Jan. 22 in the Journal of the American Chemical Society.

Star said: “The most common methods to sense gases require bulky and expensive equipment. Chip-based sensors that rely on nanomaterials for detection would be less expensive and more portable, as workers could wear them to monitor poisonous gases such as hydrogen sulfide.” Star and his team determined gold nanomaterials would be ideal for detecting hydrogen sulfide owing to gold’s high affinity for sulfur and unique physical properties of nanomaterials.

“To produce the gold nano-wires, we suspended nanotubes in water with gold-containing chloroauric acid,” said Star. “As we stirred and heated the mixture, the gold reduced and formed nanoparticles on the outer walls of the tubes. The result was a highly conductive jumble of gold nanowires and carbon nanotubes.”

To test the nanowires’ ability to detect hydrogen sulfide, the researchers cast a film of the composite material onto a chip patterned with gold electrodes. The team could detect gas at levels as low as five parts per billion — a detection level comparable to that of existing sensing techniques. They also could detect hydrogen sulfide in complex mixtures of gases simulating natural gas. Star said the group now will test the chips’ detection limits using real samples from gas wells.

Also involved in the study were NETL research physicist Dan Sorescu and Pitt chemistry graduate students Mengning Ding and Gregg Kotchey.

Funding was provided by NETL in support of ongoing research in sensor systems and diagnostics.

Better, cheaper pneumonia vaccine studied

A newly approved vaccine to prevent pneumonia in adults may do the job better and cheaper, say School of Medicine researchers in the Feb. 22 issue of the Journal of the American Medical Association.

The currently used vaccine, 23-valent pneumococcal polysaccharide vaccine (PPSV23), has been recommended for prevention of invasive pneumococcal disease (IPD) since 1983. IPD occurs when the pneumococcus bacteria gets inside normally sterile parts of the body, leading to sepsis, meningitis and other illnesses. The other, more common, type of pneumococcal disease is non-bacteremic pneumococcal pneumonia (NPP), and it’s not clear how well the current vaccine prevents this. NPP affects hundreds of thousands of people in the United States every year.

It is hoped that the new vaccine, 13-valent pneumococcal conjugate vaccine (PCV13), prevents NPP, and the FDA recently approved the use of PCV13 in adults age 50 and older on the condition that further studies show it is effective against this illness.

Using data from the Centers for Disease Control and Prevention active bacterial core surveillance, the National Hospital Discharge Survey, the Nationwide Inpatient Sample and the National Health Interview Survey, lead author Kenneth J. Smith of the Department of Medicine and colleagues modeled the efficacy and cost-effectiveness of pneumococcal vaccination strategies among groups of hypothetical adults age 50 and older.

With no vaccination, the estimated lifetime risk from age 50 and older for hospitalized NPP was 9.3 percent. For IPD it was 0.86 percent and for death due to pneumococcal disease it was 1.8 percent. Among the different vaccination strategies, PPSV23 was estimated to prevent more IPD than strategies that used only PCV13 while strategies that used two scheduled PCV13 doses were estimated to prevent more NPP.

Current recommendations call for PPSV23 to be given at age 65 and at younger ages if co-existing illnesses are present.

Researchers found that substituting the newer vaccine would be more effective at preventing disease and cost $28,900 per quality-adjusted life year (QALY) gained, less than the $34,600 per QALY gained using PPSV23.

The authors noted that the results of the study are limited because of a lack of evidence about the effectiveness of PCV13 against NPP.

Pitt collaborators on the study were Angela Wateska of medicine and Mary Patricia Nowalk, Mahlon Raymund and Richard Zimmerman of family medicine.

The study was supported by the National Institute of Allergy and Infectious Diseases.

Concussion recovery predictions possible

Early neurological indicators and symptoms can predict which concussion patients may take longer to heal, according to specialists at UPMC and the School of Medicine.

“It’s a highly variable injury,” said Michael “Micky” Collins, director of the UPMC Sports Medicine concussion program and co-investigator of the Pitt/UPMC study published in the February issue of Neurosurgery.

The study showed that specific neurocognitive “cut-off” scores derived from ImPACT (Immediate Post-concussion Assessment and Cognitive Testing) assessments improved clinicians’ ability to predict which sports-related concussions could take longer to rehabilitate. They found, in as many as 85 percent of the cases, the scores could warn when a concussion is likely to take approximately a month to heal.

“Eighty percent of concussed people recover inside of three weeks. This prognostic information allows us to develop a risk profile of athletes who don’t recover well from this injury,” Collins said. Such an objective prognosis could help clinicians to better prepare a treatment plan, arrange academic accommodations for students and set tangible expectations for return to play and school, he said.

The study reviewed 108 high-school football players who were given ImPACT tests within a median of two days after their concussions. Fifty boys averaged a 33-day recovery time before returning to play. Those longer rehabilitations could be forecast by specific cut-off scores in visual and processing-speed testing. Migraine and cognitive symptoms also appeared to have predictive power.

Study participants who scored above the threshold levels recovered within a median of seven days.

Mark Lovell, the concussion program’s founding director who has retired from UPMC, also participated in the study.


The University Times Research Notes column reports on funding awarded to Pitt researchers as well as findings arising from University research.

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