Solar voltaic cell has achieved the highest efficiency of 25 %. Credit for this goes to the researchers at the University of South Wales (UNSW)'s ARC Photovoltaic Centre of Excellence.
K.S.Parthasarathy
Contact: Peter Trute
p.trute@unsw.edu.au
61-293-851-933
University of New South Wales
Magic solar milestone reached
UNSW claims 25 percent solar cell efficiency title
UNSW's ARC Photovoltaic Centre of Excellence has again asserted its leadership in solar cell technology by reporting the first silicon solar cell to achieve the milestone of 25 per cent effiency.
The UNSW ARC Photovoltaic Centre of Excellence already held the world record of 24.7 per cent for silicon solar cell efficiency. Now a revision of the international standard by which solar cells are measured, has delivered the significant 25 per cent record to the team led by Professors Martin Green and Stuart Wenham and widened their lead on the rest of the world.
Centre Executive Research Director, Scientia Professor Martin Green, said the new world mark in converting incident sunlight into electricity was one of six new world records claimed by UNSW for its silicon solar technologies.
Professor Green said the jump in performance leading to the milestone resulted from new knowledge about the composition of sunlight.
"Since the weights of the colours in sunlight change during the day, solar cells are measured under a standard colour spectrum defined under typical operational meteorological conditions," he said.
"Improvements in understanding atmospheric effects upon the colour content of sunlight led to a revision of the standard spectrum in April. The new spectrum has a higher energy content both down the blue end of the spectrum and at the opposite red end with, dare I say it, relatively less green."
The recalibration of the international standard, done by the International Electrochemical Commission in April, gave the biggest boost to UNSW technology while the measured efficiency of others made lesser gains. UNSW's world-leading silicon cell is now six per cent more efficient than the next-best technology, Professor Green said. The new record also inches the UNSW team closer to the 29 per cent theoretical maximum efficiency possible for first-generation silicon photovoltaic cells.
Dr Anita Ho-Baillie, who heads the Centre's high efficiency cell research effort, said the UNSW technology benefited greatly from the new spectrum "because our cells push the boundaries of response into the extremities of the spectrum".
"Blue light is absorbed strongly, very close to the cell surface where we go to great pains to make sure it is not wasted. Just the opposite, the red light is only weakly absorbed and we have to use special design features to trap it into the cell," she said.
Professor Green said: "These light-trapping features make our cells act as if they were much thicker than they are. This already has had an important spin-off in allowing us to work with CSG Solar to develop commercial 'thin-film' silicon-on-glass solar cells that are over 100 times thinner than conventional silicon cells."
ARC Centre Director, Professor Stuart Wenham said the focus of the Centre is now improving mainstream production. "Our main efforts now are focussed on getting these efficiency improvements into commercial production," he said. "Production compatible versions of our high efficiency technology are being introduced into production as we speak."
The world-record holding cell was fabricated by former Centre researchers, Dr Jianhua Zhao and Dr Aihua Wang, who have since left the Centre to establish China Sunergy, one of the world's largest photovoltaic manufacturers. "China was the largest manufacturer of solar cells internationally in 2007 with 70 per cent of the output from companies with our former UNSW students either Chief Executive Officers or Chief Technical Officers", said Professor Green.
###
Media Contact: Professor Martin Green | 9385 4018 | 0411 492 416 | m.green@unsw.edu.au
UNSW Media Office: Peter Trute | 02 9385 1933 | 0410 271 826 | p.trute@unsw.edu.au
Friday, October 24, 2008
Thursday, October 23, 2008
Hydrogen sulfide discovered to be a major player in the regulation of blood pressure
This news item reveals how intricate and complicated are the biochemical mechanisms which control and keep in harmony various processes in our body.
K.S.Parthasarathy
The heart.org
http://www.theheart.org/viewArticle.do?primaryKey=913773&nl_id=tho23oct08
HEARTWIRE
Hydrogen sulfide discovered to be a major player in the regulation of blood pressure
October 23, 2008 | Michael O'Riordan
Baltimore, MD - Twenty years after US scientists won the Nobel Prize for discovering that nitric oxide (NO) is an important signaling molecule in the cardiovascular system, findings that helped identify the determinants of blood pressure, new research has uncovered yet another gas, hydrogen sulfide (H2S), that acts as a major physiologic vasodilator and regulator of blood pressure.
"Nitric oxide is unique in that it's a gas, and since mediators in the body come in chemical classes, others have wondered whether other gases could do the same sort of thing," said Dr Solomon Snyder (Johns Hopkins University School of Medicine, Baltimore, MD), one of the investigators from the study published in the October 24, 2008 issue of Science.
Made by bacteria in the intestine, H2S has been known for some time to lower blood pressures in animals injected with the gas. Investigators, however, wanted to determine the exact role of H2S as a physiologic vasorelaxant and determinant of blood-pressure levels. Speaking with heartwire, Snyder explained that researchers, including senior investigator Dr Rui Wang (Lakehead University, Thunder Bay, ON), speculated H2S might be made by cystathionine -lyase (CSE), leading to the development of a mouse model in which the gene for CSE was knocked out.
Once the gene for CSE was depleted, the researchers discovered that H2S levels in the serum, heart, aorta, and other tissues were markedly reduced.
"We discovered that in most of the body, except for the brain, hydrogen-sulfide production vanished in the knockout mice," said Solomon. "So we said, 'Aha!' We were then able to characterize these mice to see what changed about them, and of course, the first big question was: Does anything happen to the blood pressure? Sure enough, their blood pressure is markedly elevated, at least as much, if not more so, in mice in which we knock out the gene for making nitric oxide."
Compared with normal mice, blood pressure in the mutant mice peaked at 135 mm Hg when the mice were 12 weeks of age, almost 18 mm Hg higher than in the control mice.
Next steps involved testing how the mesenteric arteries of the mutant mice responded to methacholine, a neurotransmitter that is part of the relaxation pathway. When methacholine was added to the vessels of normal mice, the arteries relaxed. When it was added to the vessels of CSE-knockout mice, however, there was no relaxation of the mesenteric arteries.
"We're going to have to do a lot of work, in lots of blood vessels, and in lots of species of animals, to pin down the relative importance of nitric oxide and hydrogen sulfide, but from our work it is very clear that hydrogen sulfide is a pretty major determinant of how your blood vessels function and your blood pressure," said Snyder.
Although the two gases appear to perform similar functions, Snyder said they are unsure if nitric oxide and H2S work together or are mutually exclusive, a question that will require continued research. In terms of potential long-term clinical implications, H2S could be chemically linked with another molecule, put into a pill, and then released to regulate blood pressure, he added.
Snyder told heartwire the discovery was fascinating and that he could hardly believed the results worked out. "It was just a theory, and we kept doing lots of different experiments, with Rui Wang's lab and with my own lab, and every experiment kept coming out positive. In good science, you do all sorts of experiments to disprove your hypothesis, but nothing disproved this one."
Source
1. Yang G, Wu L, Jiang B, et al. H2S as a physiologic vasorelaxant: hypertension in mice with deletion of cystathionine -lyase. Science 2008; 322:587-590.
Related links
• Beets for blood-pressure lowering? Researchers propose novel pathway for nitrate-nitrite conversion
[Lipid/Metabolic > Lipid/Metabolic; Feb 11, 2008]
• ACCOMPLISH at 18 months: Better blood-pressure control with single-tablet combination therapy
[Lipid/Metabolic > Lipid/Metabolic; May 21, 2007]
• Nobel Prize-winning researcher criticized for not disclosing business interests
[HeartWire > News; Dec 09, 2004]
• New insights into nitric oxide in congestive heart failure make "the next step" possible
[Heart failure > Heart failure; Apr 23, 2004]
K.S.Parthasarathy
The heart.org
http://www.theheart.org/viewArticle.do?primaryKey=913773&nl_id=tho23oct08
HEARTWIRE
Hydrogen sulfide discovered to be a major player in the regulation of blood pressure
October 23, 2008 | Michael O'Riordan
Baltimore, MD - Twenty years after US scientists won the Nobel Prize for discovering that nitric oxide (NO) is an important signaling molecule in the cardiovascular system, findings that helped identify the determinants of blood pressure, new research has uncovered yet another gas, hydrogen sulfide (H2S), that acts as a major physiologic vasodilator and regulator of blood pressure.
"Nitric oxide is unique in that it's a gas, and since mediators in the body come in chemical classes, others have wondered whether other gases could do the same sort of thing," said Dr Solomon Snyder (Johns Hopkins University School of Medicine, Baltimore, MD), one of the investigators from the study published in the October 24, 2008 issue of Science.
Made by bacteria in the intestine, H2S has been known for some time to lower blood pressures in animals injected with the gas. Investigators, however, wanted to determine the exact role of H2S as a physiologic vasorelaxant and determinant of blood-pressure levels. Speaking with heartwire, Snyder explained that researchers, including senior investigator Dr Rui Wang (Lakehead University, Thunder Bay, ON), speculated H2S might be made by cystathionine -lyase (CSE), leading to the development of a mouse model in which the gene for CSE was knocked out.
Once the gene for CSE was depleted, the researchers discovered that H2S levels in the serum, heart, aorta, and other tissues were markedly reduced.
"We discovered that in most of the body, except for the brain, hydrogen-sulfide production vanished in the knockout mice," said Solomon. "So we said, 'Aha!' We were then able to characterize these mice to see what changed about them, and of course, the first big question was: Does anything happen to the blood pressure? Sure enough, their blood pressure is markedly elevated, at least as much, if not more so, in mice in which we knock out the gene for making nitric oxide."
Compared with normal mice, blood pressure in the mutant mice peaked at 135 mm Hg when the mice were 12 weeks of age, almost 18 mm Hg higher than in the control mice.
Next steps involved testing how the mesenteric arteries of the mutant mice responded to methacholine, a neurotransmitter that is part of the relaxation pathway. When methacholine was added to the vessels of normal mice, the arteries relaxed. When it was added to the vessels of CSE-knockout mice, however, there was no relaxation of the mesenteric arteries.
"We're going to have to do a lot of work, in lots of blood vessels, and in lots of species of animals, to pin down the relative importance of nitric oxide and hydrogen sulfide, but from our work it is very clear that hydrogen sulfide is a pretty major determinant of how your blood vessels function and your blood pressure," said Snyder.
Although the two gases appear to perform similar functions, Snyder said they are unsure if nitric oxide and H2S work together or are mutually exclusive, a question that will require continued research. In terms of potential long-term clinical implications, H2S could be chemically linked with another molecule, put into a pill, and then released to regulate blood pressure, he added.
Snyder told heartwire the discovery was fascinating and that he could hardly believed the results worked out. "It was just a theory, and we kept doing lots of different experiments, with Rui Wang's lab and with my own lab, and every experiment kept coming out positive. In good science, you do all sorts of experiments to disprove your hypothesis, but nothing disproved this one."
Source
1. Yang G, Wu L, Jiang B, et al. H2S as a physiologic vasorelaxant: hypertension in mice with deletion of cystathionine -lyase. Science 2008; 322:587-590.
Related links
• Beets for blood-pressure lowering? Researchers propose novel pathway for nitrate-nitrite conversion
[Lipid/Metabolic > Lipid/Metabolic; Feb 11, 2008]
• ACCOMPLISH at 18 months: Better blood-pressure control with single-tablet combination therapy
[Lipid/Metabolic > Lipid/Metabolic; May 21, 2007]
• Nobel Prize-winning researcher criticized for not disclosing business interests
[HeartWire > News; Dec 09, 2004]
• New insights into nitric oxide in congestive heart failure make "the next step" possible
[Heart failure > Heart failure; Apr 23, 2004]
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