Monday, September 5, 2011

World's Smallest Electric Motor Made from a Single MoleculeWorld's Smallest Electric Motor Made from a Single Molecule

The smallest electrical motor on the planet, at least according to Guinness World Records, is 200 nanometers. Granted, that's a pretty small motor -- after all, a single strand of human hair is 60,000 nanometers wide -- but that tiny mark is about to be shattered in a big way.

Chemists at Tufts University's School of Arts and Sciences have developed the world's first single molecule electric motor, a development that may potentially create a new class of devices that could be used in applications ranging from medicine to engineering.
In research published online Sept. 4 in Nature Nanotechnology, the Tufts team reports an electric motor that measures a mere 1 nanometer across, groundbreaking work considering that the current world record is a 200 nanometer motor. A single strand of human hair is about 60,000 nanometers wide.
According to E. Charles H. Sykes, Ph.D., associate professor of chemistry at Tufts and senior author on the paper, the team plans to submit the Tufts-built electric motor to Guinness World Records.
"There has been significant progress in the construction of molecular motors powered by light and by chemical reactions, but this is the first time that electrically-driven molecular motors have been demonstrated, despite a few theoretical proposals," says Sykes. "We have been able to show that you can provide electricity to a single molecule and get it to do something that is not just random."
Sykes and his colleagues were able to control a molecular motor with electricity by using a state of the art, low-temperature scanning tunneling microscope (LT-STM), one of about only 100 in the United States. The LT-STM uses electrons instead of light to "see" molecules.
The team used the metal tip on the microscope to provide an electrical charge to a butyl methyl sulfide molecule that had been placed on a conductive copper surface. This sulfur-containing molecule had carbon and hydrogen atoms radiating off to form what looked like two arms, with four carbons on one side and one on the other. These carbon chains were free to rotate around the sulfur-copper bond.
The team determined that by controlling the temperature of the molecule they could directly impact the rotation of the molecule. Temperatures around 5 Kelvin (K), or about minus 450 degrees Fahrenheit (ºF), proved to be the ideal to track the motor's motion. At this temperature, the Tufts researchers were able to track all of the rotations of the motor and analyze the data.
While there are foreseeable practical applications with this electric motor, breakthroughs would need to be made in the temperatures at which electric molecular motors operate. The motor spins much faster at higher temperatures, making it difficult to measure and control the rotation of the motor.
"Once we have a better grasp on the temperatures necessary to make these motors function, there could be real-world application in some sensing and medical devices which involve tiny pipes. Friction of the fluid against the pipe walls increases at these small scales, and covering the wall with motors could help drive fluids along," said Sykes. "Coupling molecular motion with electrical signals could also create miniature gears in nanoscale electrical circuits; these gears could be used in miniature delay lines, which are used in devices like cell phones."
The Changing Face of Chemistry
Students from the high school to the doctoral level played an integral role in the complex task of collecting and analyzing the movement of the tiny molecular motors.
"Involvement in this type of research can be an enlightening, and in some cases life changing, experience for students," said Sykes. "If we can get people interested in the sciences earlier, through projects like this, there is a greater chance we can impact the career they choose later in life."
As proof that gaining a scientific footing early can matter, one of the high school students involved in the research, Nikolai Klebanov, went on to enroll at Tufts; he is now a sophomore majoring in chemical engineering.
This work was supported by the National Science Foundation, the Beckman Foundation and the Research Corporation for Scientific Advancement.
Source science daily web

Tuesday, August 9, 2011

Scientist Develops Virus That Targets HIV: Using a Virus to Kill a Virus

In what represents an important step toward curing HIV, a USC scientist has created a virus that hunts down HIV-infected cells.
Dr. Pin Wang's lentiviral vector latches onto HIV-infected cells, flagging them with what is called "suicide gene therapy" -- allowing drugs to later target and destroy them.
"If you deplete all of the HIV-infected cells, you can at least partially solve the problem," said Wang, chemical engineering professor with the USC Viterbi School of Engineering.
The process is analogous to the military practice of "buddy lasing" -- that is, having a soldier on the ground illuminate a target with a laser to guide a precision bombing strike from an aircraft.
Like a precision bombing raid, the lentiviral vector approach to targeting HIV has the advantage of avoiding collateral damage, keeping cells that are not infected by HIV out of harm's way. Such accuracy has not been achieved by using drugs alone, Wang said.
So far, the lentiviral vector has only been tested in culture dishes and has resulted in the destruction of about 35 percent of existing HIV cells. While that may not sound like a large percentage, if this treatment were to be used in humans, it would likely be repeated several times to maximize effectiveness.
Among the next steps will be to test the procedure in mice. While this is an important breakthrough, it is not yet a cure, Wang said.
"This is an early stage of research, but certainly it is one of the options in that direction," he said.
Wang's research, which was funded by the National Institutes of Health, appears in the July 23 issue of Virus Research.

Wednesday, May 25, 2011

Hips Take Walking in Stride, Ankles Put Best Foot Forward in Run

In a first-of-its-kind study comparing human walking and running motions -- and whether the hips, knees or ankles are the most important power sources for these motions -- researchers at North Carolina State University show that the hips generate more of the power when people walk, but the ankles generate more of the power when humans run. Knees provide approximately one-fifth or less of walking or running power.
The research could help inform the best ways of building assistive or prosthetic devices for humans, or constructing next-generation robotics, say NC State biomedical engineers Drs. Dominic Farris and Gregory Sawicki. The co-authors of a study on the mechanics of walking and running in the journal Interface, a Royal Society scientific journal, Sawicki and Farris are part of NC State's Human PoWeR (Physiology of Wearable Robotics) Lab.
A long history of previous studies have focused on the biomechanics of human locomotion from a whole-body or individual limbs perspective. But this study is the first to zoom in on the mechanical power generated by specific lower-limb joints in a single comprehensive study of walking and running across a range of speeds, Sawicki says.
The study shows that, overall, hips generate more power when people walk. That is, until humans get to the point at which they're speed walking -- walking so fast that it feels more comfortable to run -- at 2 meters per second. Hips generate 44 percent of the power when people walk at a rate of 2 meters per second, with ankles contributing 39 percent of the power.
When people start running at this 2-meter-per-second rate, the ankles really kick in, providing 47 percent of the power compared to 32 percent for the hips. Ankles continue to provide the most power of the three lower limb joints as running speeds increase, although the hips begin closing the distance at faster speeds.
"There seems to be a tradeoff in power generation from hips to ankles as you make the transition from walking to running," Sawicki says.
Both researchers are interested in how the study can help people who need assistance walking and running. Knowing which part of the lower limbs provide more power during the different activities can help engineers figure out how, depending on the person's speed and gait, mechanical power needs to be distributed.
"For example, assistive devices such as an exoskeleton or prosthesis may have motors near both the hip and ankle. If a person will be walking and then running, you'd need to redistribute energy from the hip to the ankle when the person makes that transition," Farris says.
Ten people walked and ran at various speeds on a specially designed treadmill in the study; a number of cameras captured their gait by tracking reflective markers attached to various parts of the participants' lower limbs while the treadmill captured data from the applied force.
The study examined walking and running on level ground in order to gauge the differences brought about by increased speed; walking and running on inclined ground is fundamentally different than walking and running on flat ground, the researchers say, and would likely skew the power generation results toward the hips and knees.
Source: Daily science webs

Wednesday, May 11, 2011

Mitochondria: Body’s Power Stations Can Affect Aging

Mitochondria are the body's energy producers, the power stations inside our cells. Researchers at the University of Gothenburg, Sweden, have now identified a group of mitochondrial proteins, the absence of which allows other protein groups to stabilise the genome. This could delay the onset of age-related diseases and increase lifespan.
Some theories of human aging suggest that the power generators of the cell, the mitochondria, play a part in the process. In addition to supplying us with energy in a usable form, mitochondria also produce harmful by-products -- reactive oxyradicals that attack and damage various cell components. Eventually these injuries become too much for the cell to cope with, and it loses its capacity to maintain important functions, so the organism starts to age. That's the theory anyway. Oddly enough, several studies have shown that certain mitochondrial dysfunctions can actually delay aging, at least in fungi, worms and flies. The underlying mechanisms have yet to be determined.
In a study from the Department of Cell and Molecular Biology at the University of Gothenburg, published in the journal Molecular Cell, a research team has now identified a group of mitochondrial proteins that are involved in this type of aging regulation. The researchers found that a group of proteins called MTC proteins, which are normally needed for mitochondrial protein synthesis, also have other functions that influence genome stability and the cell's capacity to remove damaged and harmful proteins.
"When a certain MTC protein is lacking in the cell, e.g. because of a mutation in the corresponding gene, the other MTC proteins appear to adopt a new function. They then gain increased significance for the stabilisation of the genome and for combating protein damage, which leads to increased lifespan," says Thomas Nyström of the Department of Cell and Molecular Biology.
He adds, "These studies also show that this MTC-dependent regulation of the rate of aging uses the same signalling pathways that are activated in calorie restriction -- something that extends the lifespan of many different organisms, including yeasts, mice and primates. Some of the MTC proteins identified in this study can also be found in the human cell, raising the obvious question of whether they play a similar role in the regulation of our own aging processes. It is possible that modulating the activity of the MTC proteins could enable us to improve the capacity of the cell to delay the onset of age-related diseases. These include diseases related to instability of the genome, such as cancer, as well as those related to harmful proteins, such as Alzheimer's disease and Parkinson's disease. At the moment this is only speculation, and the precise mechanism underlying the role of the MTC proteins in the aging process is a fascinating question that remains to be answered."

Friday, April 22, 2011

Worm Studies Shed Light on Human Cancers

Research in the worm is shedding light on a protein associated with a number of different human cancers, and may point to a highly targeted way to treat them.
 University of Wisconsin-Madison scientists were studying a worm protein called TFG-1, which is present in many cell types but whose exact role had never been understood. The scientists discovered that the protein controls key aspects of the movement, or secretion, of growth factors out of cells.
"TFG-1 has never been implicated in the secretory process before," says Dr. Anjon Audhya, an assistant professor of biomolecular chemistry in the School of Medicine and Public Health. "It turns out that humans carry a very similar protein, and we think it plays the same role in humans as in worms."
Reviewing the scientific literature, the researchers found that the gene encoding TFG in humans is fused to at least three other genes implicated in anaplastic large cell lymphoma, papillary thyroid carcinoma and extraskeletal chondrosarcoma. The fusions occur when two broken or rearranged pieces of DNA combine to form a "chimeric" gene with completely distinct properties.
Audhya's studies of TFG-1 in the worm led him to develop a model that explains how TFG fusions may stimulate cancer in humans. As reported in the current issue of Nature Cell Biology (Advanced Online Publication), he proposes that abnormal levels of growth factor secretion may produce a rich micro-environment that helps tumors form and thrive. "We think certain properties of TFG lead it to be a very effective precursor oncogene," he says.
Normally, a growth factor primed to leave a cell is encompassed by a sac, or vesicle, and then transported from one structure inside the cell to another -- endoplasmic reticulum (ER) to Golgi -- before it leaves the cell and discharges into the extracellular space.
Through their genetic studies, the Wisconsin researchers found that TFG-1 in the worm controls vesicle formation and secretion out of the ER.
"We found TFG-1 lies at the interface between the ER and the Golgi, in a scaffolding structure called the ER exit site, where it regulates the formation of vesicles carrying their critical cargo," Audhya says.
The research revealed the precise location where TFG-1 does its work and the mechanism by which it spurs unchecked activity.
The scientists demonstrated that human TFG also functions at ER exit sites, which contain a characterized scaffolding protein called Sec16, and likely regulates secretion of multiple cargoes out of cells.
"In the case of one fusion gene, TFG-NTRK-1, the concentrated non-stop activity of NTRK-1 at ER exit sites may cause the first steps that can transform a normal cell into a cancer cell," Audhya says.
The TFG fusions offer a direct target for future "designer" therapies.
"If you identified patients who have fusion genes that express chimeric proteins, you could create a drug that affects only those proteins," he says, adding that TFG fusions leading to chimeric proteins do not exist in healthy people.
Excited about the possibility that their basic science investigations may be applied to several areas of clinical medicine, the researchers have also begun studying TFG as it relates to B-cell development and the secretion of antibodies

Functioning Synapse Created Using Carbon Nanotubes: Devices Might Be Used in Brain Prostheses or Synthetic Brains

Engineering researchers the University of Southern California have made a significant breakthrough in the use of nanotechnologies for the construction of a synthetic brain. They have built a carbon nanotube synapse circuit whose behavior in tests reproduces the function of a neuron, the building block of the brain.
The team, which was led by Professor Alice Parker and Professor Chongwu Zhou in the USC Viterbi School of Engineering Ming Hsieh Department of Electrical Engineering, used an interdisciplinary approach combining circuit design with nanotechnology to address the complex problem of capturing brain function.
In a paper published in the proceedings of the IEEE/NIH 2011 Life Science Systems and Applications Workshop in April 2011, the Viterbi team detailed how they were able to use carbon nanotubes to create a synapse.
Carbon nanotubes are molecular carbon structures that are extremely small, with a diameter a million times smaller than a pencil point. These nanotubes can be used in electronic circuits, acting as metallic conductors or semiconductors.
"This is a necessary first step in the process," said Parker, who began the looking at the possibility of developing a synthetic brain in 2006. "We wanted to answer the question: Can you build a circuit that would act like a neuron? The next step is even more complex. How can we build structures out of these circuits that mimic the function of the brain, which has 100 billion neurons and 10,000 synapses per neuron?"
Parker emphasized that the actual development of a synthetic brain, or even a functional brain area is decades away, and she said the next hurdle for the research centers on reproducing brain plasticity in the circuits.
The human brain continually produces new neurons, makes new connections and adapts throughout life, and creating this process through analog circuits will be a monumental task, according to Parker.
She believes the ongoing research of understanding the process of human intelligence could have long-term implications for everything from developing prosthetic nanotechnology that would heal traumatic brain injuries to developing intelligent, safe cars that would protect drivers in bold new ways.
Source: daily science web

Monday, March 21, 2011

Pregnancy - 15 Things Women Wish she Knew the First Time Around

After three pregnancies and three wonderful baby girls, I have (let's hope) learned a few things. 

Ok, I’ll admit it: growing up, I was one of those girls who used to stick a pillow under her shirt and look in the mirror, day dreaming of the day I’d become a mommy. I always knew that I wanted kids, and looked forward to the day when that dream would become a reality. When I was newly pregnant with our first daughter, I was on cloud nine. I loved thinking, reading, and talking about my pregnancy. Despite my euphoric haze, though, there are a few things I wish I had known at the time:

  1. Don’t worry so much. In general. This is a broad suggestion, but I really wish I had not worried so much. If you had a beer the night before you found out you’re pregnant, the baby is fine. If you ate three hot dogs and then read that pregnant women shouldn’t eat hot dogs, make a mental note and move on. And don’t worry about being a good mom – you’ll be just fine.
  2. Morning sickness will probably not be what you expect. I was shocked, and convinced I had the flu the first week (even though I knew I was pregnant). Just remember that if it hits you hard, it will pass. Also, you may be one of the lucky ones who don’t get it, or who feel mildly queasy and that’s it. Just don’t set up expectations, like expecting to only get sick in the morning, or thinking that it ends right at 12 weeks. Let your body do what it’s going to do, and just hang in there!
  3. Buy frozen foods and a lot of convenience food before you start feeling nauseous. I wish I had done this – we would have saved a ton of money on take-out and fast food! You may be fine and keep cooking as usual, but I was way too sick to stand the smell of raw meat, doing dishes, or anything else that triggered my gag reflex. Buy frozen lasagna, frozen dinners, and lots of snack stuff. Also stock up on paper plates. Having things on hand will be very helpful when you are either feeling too tired or too sick to cook.
  4. If you take everyone’s advice too seriously, you’ll make yourself miserable. Every one has an opinion, and over the course of your pregnancy, you are going to hear tons of stories, lots of warnings, and plenty of advice. Take it all with a grain of salt – and don’t let it stress you out. Society feels the responsibility to educate and advise pregnant women on just about everything, but it often just causes more stress. Let it roll off of your back.
  5. Don’t be in a rush to wear maternity clothes. I was so excited during my first pregnancy to finally “look pregnant,” I rushed into maternity clothes. I could have gone another month or so, but I was just too excited. Trust me – you will have plenty of time to wear those clothes (and you’ll get sick of them), so enjoy your regular clothes while you still can.
  6. Invest in a belly band. This will extend the life of your pre-pregnancy pants, and will help you with your clothing options. These wonderful things are nice, stretchy bands that enable you to walk around with your pants unzipped, while still held up in place with a nice band covering the zipper. (An added benefit of these bands – they help you get back into your old jeans after having the baby, when you are still carrying some baby weight in your middle.)
  7. Don’t obsess about your pregnancy. When people ask you how you are feeling, try not to go into a monologue about how you threw up yesterday, need to pee every hour, and then give them a long list of all the baby names you are considering. When it comes down to it, most people are asking to be polite. It’s completely normal to want to gush about your pregnancy, but just remember that non-pregnant people may not be as interested as you are in certain things. I was bad about that when I was pregnant with my first, so I can completely understand this – and I wish I had realized it at the time. It’s better to save the gory details for a pregnancy journal, your mom, or your best friend.
  8. A regular soda here and there is fine. Dr. Pepper helped me make it through the end of my first trimester – I wish I had lightened up earlier on. Sure, you aren’t supposed to have tons of caffeine – but a smidge here and there won’t hurt.
  9. Avoid saying, “I will never do that!” Before you actually become a parent, you just don’t know. You may end up co-sleeping with your baby, deciding to get the epidural, or stop nursing after a couple of months. Keep an open mind, and don’t set yourself up for a disappointment.
  10. Don’t feel bad about sleeping in. Sleep while you can. Trust me.
  11. Buy at least one or two fabulous nursing bras. I made the mistake of buying cheap nursing bras when I was still pregnant with my first baby, thinking it didn’t matter. Well, think again. You will need a lot of support during those first few months. I am in love with Bravado bras, because (a) they are crazy comfy, (b) you can sleep in them, and (c) these bras come in many patterns and colors. I have four of the “original nursing bras” and I love them. My favorite is the leopard print – just because you’re nursing doesn’t mean you can’t still be hot!
  12. Be clear about what you want before and after labor, but don’t come up with an elaborate birth plan that spells out exactly how you want it to go. Labor and delivery are full of surprises, so don’t set yourself up thinking it will go a certain way. Do be clear on what you want regarding pain meds, who is allowed in the room with you, the doc’s policy on episiotomies, etc.
  13. You don’t need as much as you think. I was so OCD when I was pregnant. I worried way too much about “getting ready” for the baby, and looking back, I realize now it was bit overboard. When it comes down to it, Target will still exist after you arrive home from the hospital. You husband can go out and buy a bouncy seat or some extra blankets when you are resting at home with the baby, so don’t worry about having everything just right.
  14. Let the hospital nursery take the baby overnight. They will still bring your baby in to nurse during the night, but at least you’ll get some sleep. We chose to “room in” with our first baby, because I was concerned that I’d look bad if I sent her to the nursery. Big mistake. Let the nurses take care of the baby while you have the opportunity – you will have plenty of sleepless nights once you arrive home.
  15. Above all, I wish I had known how much I’d love my kids. I know this sounds cheesy, but it’s true. You have absolutely no idea how much you are going to fall in love with your children until you are staring into their tiny faces at 5am, counting their eyelashes. Once you realize how much you love that little person you saw on the ultrasound screen, it blows your mind. Motherhood is out of this world. Sit back, relax, and enjoy the months leading up to it.