QuoteReplyTopic: Science and Nature News Redux Posted: 17-May-2013 at 00:13
Artificial Forest for Solar Water-Splitting: First Fully Integrated Artificial Photosynthesis Nanosystem
Schematic shows TiO2 nanowires (blue) grown on the upper half of a Si nanowire (gray) and the two absorbing different regions of the solar spectrum. Insets display photoexcited electronhole pairs separated at the semiconductor-electrolyte interface to carry out water splitting with the help of co-catalysts (yellow and gray dots).
In the wake of the sobering news that atmospheric carbon dioxide is now at its highest level in at least three million years, an important advance in the race to develop carbon-neutral renewable energy sources has been achieved. Scientists with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have reported the first fully integrated nanosystem for artificial photosynthesis. While "artificial leaf" is the popular term for such a system, the key to this success was an "artificial forest."
"Similar to the chloroplasts in green plants that carry out photosynthesis, our artificial photosynthetic system is composed of two semiconductor light absorbers, an interfacial layer for charge transport, and spatially separated co-catalysts," says Peidong Yang, a chemist with Berkeley Lab's Materials Sciences Division, who led this research. "To facilitate solar water- splitting in our system, we synthesized tree-like nanowire heterostructures, consisting of silicon trunks and titanium oxide branches. Visually, arrays of these nanostructures very much resemble an artificial forest."
Yang, who also holds appointments with the University of California Berkeley's Chemistry Department and Department of Materials Science and Engineering, is the corresponding author of a paper describing this research in the journal NANO Letters. The paper is titled "A Fully Integrated Nanosystem of Semiconductor Nanowires for Direct Solar Water Splitting." Co-authors are Chong Liu, Jinyao Tang, Hao Ming Chen and Bin Liu.
Solar technologies are the ideal solutions for carbon-neutral renewable energy -- there's enough energy in one hour's worth of global sunlight to meet all human needs for a year. Artificial photosynthesis, in which solar energy is directly converted into chemical fuels, is regarded as one of the most promising of solar technologies. A major challenge for artificial photosynthesis is to produce hydrogen cheaply enough to compete with fossil fuels. Meeting this challenge requires an integrated system that can efficiently absorb sunlight and produce charge-carriers to drive separate water reduction and oxidation half-reactions.
"In natural photosynthesis the energy of absorbed sunlight produces energized charge-carriers that execute chemical reactions in separate regions of the chloroplast," Yang says. "We've integrated our nanowire nanoscale heterostructure into a functional system that mimics the integration in chloroplasts and provides a conceptual blueprint for better solar-to-fuel conversion efficiencies in the future."
When sunlight is absorbed by pigment molecules in a chloroplast, an energized electron is generated that moves from molecule to molecule through a transport chain until ultimately it drives the conversion of carbon dioxide into carbohydrate sugars. This electron transport chain is called a "Z-scheme" because the pattern of movement resembles the letter Z on its side. Yang and his colleagues also use a Z-scheme in their system only they deploy two Earth abundant and stable semiconductors -- silicon and titanium oxide -- loaded with co-catalysts and with an ohmic contact inserted between them. Silicon was used for the hydrogen-generating photocathode and titanium oxide for the oxygen-generating photoanode. The tree-like architecture was used to maximize the system's performance. Like trees in a real forest, the dense arrays of artificial nanowire trees suppress sunlight reflection and provide more surface area for fuel producing reactions............
So it would seem that it doesn't matter if you've been trying to keep yourself fit, because if you become very stressed due to the work you do, become very stressed due to the work, yes if you didn't need anymore stress, it would seem that the stress puts a lot of pressure on your heart and cardiovascular system. OK you stressed individuals, has this made you become very stressed indeed now reading this.
Work-Related Stress Linked to Increased Blood Fat Levels, Cardiovascular Health Risks
Spanish researchers have studied how job stress affects cardiovascular health. The results, published in the 'Scandinavian Journal of Public Health', link this situation to dyslipidemia, a disorder that alters the levels of lipids and lipoproteins in the blood.
Experts have been saying for years that emotional stress is linked to the risk of suffering cardiovascular disease as a result of unhealthy habits such as smoking, an unsuitable diet or leading a sedentary lifestyle, among other factors.
Now, a study conducted by the Sociedad de Prevención de Ibermutuamur, in collaboration with experts from the Virgen de la Victoria Hospital (Malaga) and the Santiago de Compostela University, analyses the relationship between job stress and different parameters associated with how fatty acids are metabolised in the body.
The study, published recently in the Scandinavian Journal of Public Health, was conducted on a sample population of more than 90,000 workers undergoing medical check-ups.
"The workers who stated that they had experienced difficulties in dealing with their job during the previous twelve months (8.7% of the sample) had a higher risk of suffering from dyslipidemia," Carlos Catalina, clinical psychologist and an expert in work-related stress, said.
Dyslipidemia is a lipoproteins' metabolic disorder that can manifest itself in an increase in total cholesterol, low-density lipoproteins (LDLs) and triglyceride levels, in addition to a drop in high-density lipoproteins (HDLs).
Changes in the lipid profile
Specifically, in the study the workers with job stress were more likely to suffer from abnormally high levels of LDL cholesterol (the so-called 'bad' cholesterol), excessively low levels of HDL cholesterol (the 'good' cholesterol) and positive atherogenic indices, i.e. potential artery blockage.
"One of the mechanisms that could explain the relationship between stress and cardiovascular risk could be the changes in our lipid profile, which means higher rates of atheromatous plaque accumulation (lipids deposit) in our arteries," Catalina concluded.
Meteoroid impact triggers bright flash on the moon
NASA handout photo of meteoroid impacts on the moon, detected by NASA's lunar monitoring program
An automated telescope monitoring the moon has captured images of an 88-pound (40 kg) rock slamming into the lunar surface, creating a bright flash of light, NASA scientists said on Friday.
The explosion on March 17 was the biggest seen since NASA began watching the moon for meteoroid impacts about eight years ago. So far, more than 300 strikes have been recorded.
"It exploded in a flash nearly 10 times as bright as anything we've ever seen before," Bill Cooke, with NASA's Meteoroid Environment Office at the Marshall Space Flight Center in Huntsville, Alabama, said in a statement.
A NASA satellite orbiting the moon is now on a hunt for the newly formed crater, which scientists estimate could be as wide as 66 feet.
The flash was so bright that anyone looking at the moon at the moment of impact could have seen it without a telescope, NASA said.
After reviewing digital recordings made by one of the program's telescopes, scientists determined the space rock was about 1 foot in diameter, and traveling about 56,000 mph when it slammed into the moon and exploded with the force of five tons of TNT.
That same night, cameras detected an unusually high number of meteors blasting through Earth's atmosphere as well. Most meteors burn up well before reaching the ground.
But not always. In February, an asteroid estimated to be about 66 feet in diameter exploded over Chelyabinsk, Russia, damaging buildings and shattering glass, leaving more than 1,500 injured. It was the largest object to strike Earth since 1908.
"The Russian fireball was many orders of magnitude larger and possessed 100,000 times more energy," than the lunar impact, Cooke wrote in an email to Reuters.
He believes the lunar impact and the March 17 meteor shower on Earth are related, the result of both bodies traveling together through a region of space sprinkled with small rocks and dust.
"We'll be keeping an eye out for signs of a repeat performance next year when the Earth-moon system passes through the same region of space," Cooke said.
Though this is progress, its significance will not be realized until something is devised to help stop you forget your past memories now which identifies you as the person you know as you.
Molecular Trigger for Alzheimer's Disease Identified
This is an image, magnified a million times, of amyloid fibril, the type of protein structures that are formed in Alzheimer's.
Researchers have pinpointed a catalytic trigger for the onset of Alzheimer’s disease – when the fundamental structure of a protein molecule changes to cause a chain reaction that leads to the death of neurons in the brain.
For the first time, scientists at Cambridge’s Department of Chemistry have been able to map in detail the pathway that generates “aberrant” forms of proteins which are at the root of neurodegenerative conditions such as Alzheimer’s.
They believe the breakthrough is a vital step closer to increased capabilities for earlier diagnosis of neurological disorders such as Alzheimer’s and Parkinson’s, and opens up possibilities for a new generation of targeted drugs, as scientists say they have uncovered the earliest stages of the development of Alzheimer’s that drugs could possibly target.
The study, published today in the Proceedings of the National Academy of Sciences, is a milestone in the long-term research established in Cambridge by Professor Christopher Dobson and his colleagues, following the realisation by Dobson of the underlying nature of protein ‘misfolding’ and its connection with disease over 15 years ago.
The research is likely to have a central role to play in diagnostic and drug development for dementia-related diseases, which are increasingly prevalent and damaging as populations live longer.
“There are no disease modifying therapies for Alzheimer’s and dementia at the moment, only limited treatment for symptoms. We have to solve what happens at the molecular level before we can progress and have real impact,” said Dr Tuomas Knowles, lead author of the study and long-time collaborator of Professor Dobson.
“We’ve now established the pathway that shows how the toxic species that cause cell death, the oligomers, are formed. This is the key pathway to detect, target and intervene – the molecular catalyst that underlies the pathology.”
In 2010, the Alzheimer’s Research Trust showed that dementia costs the UK economy over £23 billion, more than cancer and heart disease combined. Just last week, PM David Cameron urged scientists and clinicians to work together to “improve treatments and find scientific breakthroughs” to address “one of the biggest social and healthcare challenges we face.”
The neurodegenerative process giving rise to diseases such as Alzheimer’s is triggered when the normal structures of protein molecules within cells become corrupted.
Protein molecules are made in cellular ‘assembly lines’ that join together chemical building blocks called amino acids in an order encoded in our DNA. New proteins emerge as long, thin chains that normally need to be folded into compact and intricate structures to carry out their biological function.
Under some conditions, however, proteins can ‘misfold’ and snag surrounding normal proteins, which then tangle and stick together in clumps which build to masses, frequently millions, of malfunctioning molecules that shape themselves into unwieldy protein tendrils.
The abnormal tendril structures, called ‘amyloid fibrils’, grow outwards around the location where the focal point, or 'nucleation' of these abnormal “species” occurs.
Amyloid fibrils can form the foundations of huge protein deposits – or plaques – long-seen in the brains of Alzheimer’s sufferers, and once believed to be the cause of the disease, before the discovery of ‘toxic oligomers’ by Dobson and others a decade or so ago.
A plaque’s size and density renders it insoluble, and consequently unable to move. Whereas the oligomers, which give rise to Alzheimer's disease, are small enough to spread easily around the brain - killing neurons and interacting harmfully with other molecules - but how they were formed was until now a mystery.
The new work, in large part carried out by researcher Samuel Cohen, shows that once a small but critical level of malfunctioning protein ‘clumps’ have formed, a runaway chain reaction is triggered that multiplies exponentially the number of these protein composites, activating new focal points through ‘nucleation’.
It is this secondary nucleation process that forges juvenile tendrils, initially consisting of clusters that contain just a few protein molecules. Small and highly diffusible, these are the ‘toxic oligomers’ that careen dangerously around the brain cells, killing neurons and ultimately causing loss of memory and other symptoms of dementia.
The researchers brought together kinetic experiments with a theoretical framework based on master equations, tools commonly used in other areas of chemistry and physics but had not been exploited to their full potential in the study of protein malfunction before.
The latest research follows hard on the heels of another ground breaking study, published in April of this year again in PNAS, in which the Cambridge group, in Collaboration with Colleagues in London and at MIT, worked out the first atomic structure of one of the damaging amyloid fibril protein tendrils. They say the years spent developing research techniques are really paying off now, and they are starting to solve “some of the key mysteries” of these neurodegenerative diseases.
“We are essentially using a physical and chemical methods to address a biomolecular problem, mapping out the networks of processes and dominant mechanisms to ‘recreate the crime scene’ at the molecular root of Alzheimer’s disease,” explained Knowles.
“Increasingly, using quantitative experimental tools and rigorous theoretical analysis to understand complex biological processes are leading to exciting and game-changing results. With a disease like Alzheimer’s, you have to intervene in a highly specific manner to prevent the formation of the toxic agents. Now we’ve found how the oligomers are created, we know what process we need to turn off.”
Just when you imagine you become totally paranoid now after reading the last post thinking that maybe an innovation wouldn't come fast enough in case you got alzheimers, here would seem to be a light at the end of the tunnel.
Drawing Closer to Alzheimer’s Magic Bullet? Drugs Found to Both Prevent and Treat Alzheimer's Disease in Mice
Imagine a pharmaceutical prevention, treatment or even cure for Alzheimer's disease.
It is almost impossible to overstate how monumental a development that would be and how it would answer the prayers of millions.
Though science isn't there yet, a new study published in The Journal of Neuroscience spearheaded by USC Davis School of Gerontology researchers offers a tantalizing glimpse of potential solutions.
"Our data suggests the possibility of drugs that can prevent and treat Alzheimer's," said lead author, professor and lab principal Christian Pike of USC Davis. "It's just mouse data but extremely encouraging mouse data."
The team studied the effects of a class of drugs called TSPO ligands on male mice that were genetically engineered to develop Alzheimer's disease, known as 3xTg-AD mice. Because a key mechanism of TSPO ligands is to increase production of steroid hormones, it was important to ensure that the mice had low levels of testosterone and related hormones before treatment. Younger mice were castrated while, in older mice, the decrease occurred as a normal consequence of aging.
"We looked at the effects of TSPO ligands in young adult mice when pathology was at an early stage and in aged mice when pathology was quite severe," Pike said. "TSPO ligands reduced measures of pathology and improved behavior at both ages."
The most surprising finding for Pike and his team was the effect of TSPO ligands in the aged mice. Four treatments -- one per week over four weeks -- in aged 3xTg-AD mice resulted in significant lowering of Alzheimer's-related pathology and improvements in memory behavior. This finding suggested the possibility that TSPO ligands can reverse components of Alzheimer's and thus have the potential to be useful in treatment.
For humans, these findings may indeed be quite significant.
"TSPO ligands are currently used in humans in certain types of neuroimaging. Newer TSPO ligands are at the clinical trials stage of development for treatment of anxiety and other conditions," Pike said. "There is a strong possibility that TSPO ligands similar to the ones used in our study could be evaluated for therapeutic efficacy in Alzheimer's patients within the next few years."
In light of the findings, the team will next focus on understanding how TSPO ligands reduce Alzheimer's pathology. Building on the established knowledge that TSPO ligands can act protectively by reducing inflammation, shielding nerve cells from injury and increasing the production of neuroactive hormones in the brain, the team will study which of these actions is the most significant in fighting Alzheimer's so it can develop newer TSPO ligands accordingly.
While Pike and his team acknowledged that the findings represent an exciting possibility, the researchers also stressed that it is by no means a given.
"From the optimistic perspective, our data provide very promising findings with tangible potential benefits for both the prevention and treatment of Alzheimer's," Pike said. "On the pessimistic side, research scientists have developed many interventions that cured Alzheimer's in mice but have failed to show significant benefits in humans. A critical direction we are currently pursuing is successfully translating these findings into humans."
Baby's Life Saved With Groundbreaking 3-D Printed Device That Restored His Breathing
Every day, their baby stopped breathing, his collapsed bronchus blocking the crucial flow of air to his lungs. April and Bryan Gionfriddo watched helplessly, just praying that somehow the dire predictions weren't true.
"Quite a few doctors said he had a good chance of not leaving the hospital alive," says April Gionfriddo, about her now 20-month-old son, Kaiba. "At that point, we were desperate. Anything that would work, we would take it and run with it."
They found hope at the University of Michigan, where a new, bioresorbable device that could help Kaiba was under development. Kaiba's doctors contacted Glenn Green, M.D., associate professor of pediatric otolaryngology at the University of Michigan.
Green and his colleague, Scott Hollister, Ph.D., professor of biomedical engineering and mechanical engineering and associate professor of surgery at U-M, went right into action, obtaining emergency clearance from the Food and Drug Administration to create and implant a tracheal splint for Kaiba made from a biopolymer called polycaprolactone.
On February 9, 2012, the specially-designed splint was placed in Kaiba at C.S. Mott Children's Hospital. The splint was sewn around Kaiba's airway to expand the bronchus and give it a skeleton to aid proper growth. Over about three years, the splint will be reabsorbed by the body. The case is featured today in the New England Journal of Medicine.
"It was amazing. As soon as the splint was put in, the lungs started going up and down for the first time and we knew he was going to be OK," says Green.
Green and Hollister were able to make the custom-designed, custom-fabricated device using high-resolution imaging and computer-aided design. The device was created directly from a CT scan of Kaiba's trachea/bronchus, integrating an image-based computer model with laser-based 3D printing to produce the splint.
"Our vision at the University of Michigan Health System is to create the future of health care through discovery. This collaboration between faculty in our Medical School and College of Engineering is an incredible demonstration of how we achieve that vision, translating research into treatments for our patients," says Ora Hirsch Pescovitz, M.D., U-M executive vice president for medical affairs and CEO of the U-M Health System.
"Groundbreaking discoveries that save lives of individuals across the nation and world are happening right here in Ann Arbor. I continue to be inspired and proud of the extraordinary people and the amazing work happening across the Health System."
Kaiba was off ventilator support 21 days after the procedure, and has not had breathing trouble since then.
"The material we used is a nice choice for this. It takes about two to three years for the trachea to remodel and grow into a healthy state, and that's about how long this material will take to dissolve into the body," says Hollister.
"Kaiba's case is definitely the highlight of my career so far. To actually build something that a surgeon can use to save a person's life? It's a tremendous feeling."
The image-based design and 3D biomaterial printing process can be adapted to build and reconstruct a number of tissue structures. Green and Hollister have already utilized the process to build and test patient specific ear and nose structures in pre-clinical models. In addition, the method has been used by Hollister with collaborators to rebuild bone structures (spine, craniofacial and long bone) in pre-clinical models.
Severe tracheobronchomalacia is rare. About 1 in 2,200 babies are born with tracheomalacia and most children grow out of it by age 2 or 3, although it often is misdiagnosed as asthma that doesn't respond to treatment.
Severe cases, like Kaiba's, are about 10 percent of that number. And they are frightening, says Green. A normal cold can cause a baby to stop breathing. In Kaiba's case, the family was out at a restaurant when he was six weeks old and he turned blue.
"Severe tracheobronchomalacia has been a condition that has bothered me for years," says Green. "I've seen children die from it. To see this device work, it's a major accomplishment and offers hope for these children."
Before the device was placed, Kaiba continued to stop breathing on a regular basis and required resuscitation daily.
"Even with the best treatments available, he continued to have these episodes. He was imminently going to die. The physician treating him in Ohio knew there was no other option, other than our device in development here," Green says.
Kaiba is doing well and he and his family, including an older brother and sister, live in Ohio.
"He has not had another episode of turning blue," says April. "We are so thankful that something could be done for him. It means the world to us."
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Topic: Science and Nature News Redux
