The electron microscope images, created by scientists at the U s. Department of energy's Brookhaven National Laboratory with partners from Stony Brook University and Rockefeller University,
""This work is a continuation of our longstanding research using electron microscopy to understand the mechanism of DNA replication,
an essential function for every living cell,"said Huilin Li, a biologist with a joint appointment at Brookhaven Lab and Stony Brook University."
and separates the two strands of the DNA double helix as it passes through a central pore in the structureand how the helicase coordinates with the two'polymerase'enzymes that duplicate each strand to copy the genome."
when DNA is miscopieda major source of mutation that can lead to canceror learn more about how a single cell can eventually develop into the many cell types that make up a multicellular organism.
and work are based on biochemical and genetic studies, "Li said, likening the situation to the famous parable of the three blind men trying to describe an elephant,
and C bases of the genetic code) to the side-by-side split ends as they move out of the helicase to form two new complete double helix DNA strands.
which is a recruitment factor for the DNA-replication primase-polymerase, b) helicase, Ctf4, and primase-polymerase (dark blue),
which works with the back-end polymerase, c) helicase, Ctf4, and front-end polymerase (green), d) helicase and front-end polymerase, e) helicase, Ctf4, front-end polymerase,
Panels a-c used an unprimed short DNA fork, and d-e used a longer and primed DNA fork.
The electron micrographs show that the replisome is a 20-nanometer sized nanomachine. click on image to enlarge) To test these assumptions,
Jingchuan Sun, an EM expert in Li's lab, was essential to the success of the work.
and provided by Roxana Georgescu in Michael O'Donnell's research group at Rockefeller University.
O'Donnell's group had published previously biochemical results related to this work.""DNA replication is one of the most fundamental processes of life,
so it is every biochemist's dream to see what a replisome looks like, "Sun said."
Yi Shi, a postdoctoral fellow in Chait's group performed this work, which confirmed the electron-microscopy-based conclusion about the unexpected architecture of the replisome.
The scientists are conducting additional studies to explore the biological significance of this unexpected location.
as the single strand moves over other portions of the structure, some"surveillance"protein components check for lesions or mistakes in the nucleotide sequence before it gets copieda sort of molecular quality control.
This architecture could also potentially play an important role in developmental biology by providing a pathway for treating the two daughter strands differently.
#Researchers show how new hydrogel can facilitate microsurgery Skillful surgeons can do amazing things in extremely small places,
In an article just published in the journal Nature Nanotechnology("A multiphase transitioning peptide hydrogel for suturing ultrasmall vessels),
"several University of Delaware researchers show how a new peptide-based hydrogel could one day make that reconnection process easier to perform
and Joel Schneider, who was a professor at UD and now is in the Chemical Biology laboratory at the National Cancer Institute.
Also part of the study were researchers from Johns hopkins university School of medicine and the Department of Electrical and Computer engineering at Johns Hopkins. Smith designed the peptide,
building on a self-assembling process developed more than a decade ago by Schneider while he was a professor in UD's Department of chemistry and Biochemistry,
and Darrin Pochan, professor and chair of UD's Department of Materials science and engineering. Nagy-Smith did the microscopy
using a transmission electron microscope at the National Cancer Institute to show how the fibers change
when exposed to ultraviolet light. The way tiny vessels are reconnected now includes stitches applied in microsurgery.
But the tiny, thin-walled vessels are fragile and prone to damage in handling. The peptide-based hydrogel can be tuned in precise ways with a specific amino acid,
and found the hydrogel would form a semi-solid to support the walls of the tiny vessel,
so,"said Smith, who now works at Glaxo Smith Kline.""There are attractive forces at work-these are hydrophobic,
allowing surgeons to make an easier connection.""This would help in any type of surgery where you are trying to restore as many vessels as you can,
whether in a whole transplant or in damaged tissue from some kind of accident,"Nagy-Smith said."
"It not only holds the vessel open, it actually sticks vessels in place without using a lot of clamps.
The surgeon essentially has a third hand.""Tested with mice, whose femoral arteries are about 200 microns in diameter-four
and transplant surgeries and also could open up new possibilities in research h
#Artificial material mimics photosynthesis A Florida State university researcher has discovered an artificial material that mimics photosynthesis
and potentially creates a sustainable energy source. In The Journal of Physical chemistry("Birnessite: A Layered Manganese Oxide To Capture Sunlight for Water-Splitting Catalysis"),Assistant professor of Chemical engineering Jose L. Mendoza-Cortes details how this new material efficiently captures sunlight and then,
how the energy can be used to break down water into oxygen (O2) and hydrogen (H2). This process is known as oxidation,
and it is also what happens during photosynthesis when a plant uses light to break down water and carbohydrates,
which are the main energy sources for the plant. His discovery generates exciting new prospects for how this process could be used to forge new energy sources in a carbon neutral way.
Potentially, hydrogen could be transported to other locations and burned as fuel.""In theory, this should be a self-sustaining energy source,
"Mendoza-Cortes said.""Perhaps in the future, you could put this material on your roof and it could turn rain water into energy with the help of the sun."But, unlike many other energy sources,
this won't have a negative effect on the environment.""You won't generate carbon dioxide or waste, "he said.
Mendoza-Cortes, a computational and theoretical chemist, said the challenge he faced was designing something that didn't rust from the process of breaking down water that also trapped the energy
and was inexpensive to create. To do this, he initially developed a multilayered material out of manganese oxide, commonly known as birnessite.
But something exciting happened when Mendoza-Cortes and his team peeled back the layers of the material so just a single layer of the material remained--it began trapping light at a much faster rate.
In technical terms it transitioned from an indirect band gap material to a direct band gap one.
Light with photo energy can penetrate indirect band gap materials much more easily without getting absorbed
and used for other purposes. Silicon, for example, is the most commonly known indirect gap band material.
But to make the material effective, silicon solar cells are stacked typically and thus hundreds of micrometers thick.
If they were any thinner, light would simply pass through them. Creating a single-layer material that can efficiently trap light is a much more desirable outcome
because it is much simpler and cheaper to manufacture.""This is why the discovery of this direct band gap material is so exciting,
"Mendoza-Cortes said.""It is cheap, it is efficient and you do need not a large amount to capture enough sunlight to carry out fuel generation
#Ultrasensitive sensors made from boron-doped graphene Ultrasensitive gas sensors based on the infusion of boron atoms into graphene--a tightly bound matrix of carbon atoms--may soon be possible, according to an international team of researchers
but it is also a highly sensitive gas sensor. With the addition of boron atoms, the boron graphene sensors were able to detect noxious gas molecules at extremely low concentrations, parts per billion in the case of nitrogen oxides and parts per million for ammonia
"will open a path to high-performance sensors that can detect trace amounts of many other molecules."
"said Mauricio Terrones, professor of physics, chemistry and materials science at Penn State.""We were previously able to dope graphene with atoms of nitrogen,
we collaborated with experts in the United states and around the world to confirm our research and test the properties of our material."
Once fabricated, the researchers sent boron graphene samples to researchers at the Honda Research Institute USA Inc.,Columbus, Ohio, who tested the samples against their own highly sensitive gas sensors.
Konstantin Novoselov's lab at the University of Manchester UK, studied the transport mechanism of the sensors.
Novoselov was the 2010 Nobel laureate in physics. Theory collaborators in the U s. and Belgium matched the scanning tunneling microscopy images to experimental images,
"This multidisciplinary research paves a new avenue for further exploration of ultrasensitive gas sensors, "said Avetik Harutyunyan,
chief scientist and project leader at Honda Research Institute USA Inc."Our approach combines novel nanomaterials with continuous ultraviolet light radiation in the sensor design that have been developed in our laboratory by lead researcher Dr
which is up to six orders of magnitude better sensitivity than current state-of-the-art sensors.""These sensors can be used for labs and industries that use ammonia, a highly corrosive health hazard,
or to detect nitrogen oxides, a dangerous atmospheric pollutant emitted from automobile tailpipes. In addition to detecting toxic or flammable gases,
theoretical work indicates that boron-doped graphene could lead to improved lithium-ion batteries and field-effect transistors, the authors report t
#Researchers create transplantation model for 3-D printed constructs Using sugar, silicone and a 3-D printer,
a team of bioengineers at Rice university and surgeons at the University of Pennsylvania have created an implant with an intricate network of blood vessels that points toward a future of growing replacement tissues and organs for transplantation.
The research may provide a method to overcome one of the biggest challenges in regenerative medicine:
How to deliver oxygen and nutrients to all cells in an artificial organ or tissue implant that takes days
or weeks to grow in the lab prior to surgery. The new study was performed by a research team led by Jordan Miller, assistant professor of bioengineering at Rice,
and Pavan Atluri, assistant professor of surgery at Penn. The study showed that blood flowed normally through test constructs that were connected surgically to native blood vessels.
The report was published in the journal Tissue Engineering Part C: Methods. Miller said one of the hurdles of engineering large artificial tissues,
such as livers or kidneys, is keeping the cells inside them alive. Tissue engineers have relied typically on the body's own ability to grow blood vessels--for example,
by implanting engineered tissue scaffolds inside the body and waiting for blood vessels from nearby tissues to spread to the engineered constructs.
In this study, we are taking the first step toward applying an analogy from transplant surgery to 3-D printed constructs we make in the lab."Miller
"What a surgeon needs in order to do transplant surgery isn't just a mass of cells;
the surgeon needs a vessel inlet and an outlet that can be connected directly to arteries and veins,
"he said. Bioengineering graduate student Samantha Paulsen and research technician Anderson Ta worked together to develop a proof-of-concept construct--a small silicone gel about the size of a small candy gummy bear--using 3-D printing.
But rather than printing a whole construct directly, the researchers fabricated sacrificial templates for the vessels that would be inside the construct.
Using an open-source 3-D printer that lays down individual filaments of sugar glass one layer at a time
After the gel cured, Miller's team dissolved the sugar, leaving behind a network of small channels in the silicone."
but they have some of the key features relevant for a transplant surgeon, "Miller said."
"Collaborating surgeons at Penn in Atluri's group connected the inlet and outlet of the engineered gel to a major artery in a small animal model.
"This study provides a first step toward developing a transplant model for tissue engineering where the surgeon can directly connect arteries to an engineered tissue,
#Scientists discover the gene that will open the door for space-based food production Queensland University of Technology (QUT) scientists have discovered the gene that will open the door for space-based food production.
Professor Peter Waterhouse, a plant geneticist at QUT, discovered the gene in the ancient Australian native tobacco plant Nicotiana benthamiana, known as Pitjuri to indigenous Aboriginals tribes.
Professor Waterhouse made the discovery while tracing the history of the Pitjuri plant, which for decades has been used by geneticists as a model plant upon
which to test viruses and vaccines.""This plant is the'laboratory rat'of the molecular plant world,
"he said, "we think of it as a magical plant with amazing properties.""We now know that in 1939 its seeds were sent by an Australian scientist to a scientist in America
"By sequencing its genome and looking through historical records we have been able to determine that the original plant came from the Granites area near the Western australia and Northern territory border,
close to where Wolf Creek was filmed.""We know, through using a molecular clock and fossil records,
"What we found may have a big impact on future plant biotechnology research, "Dr Bally said."
"We have discovered that it is the plant equivalent of the nude mouse used in medical research.""
'and has done that to focus its energies on being able to germinate and grow quickly, rapidly flower,
"Professor Waterhouse, a molecular geneticist with QUT's Centre for Tropical Crops and Biocommodities, said scientists could use this discovery to investigate other niche
or sterile growing environments where plants were protected from disease --and space was an intriguing option."
Professor Waterhouse said the team's findings also have implications for future genetic research back here On earth."
So just as nude mice can be really good models for cancer research, 'nude'versions of crop plants could also speed up agricultural research,
"he said. Professor Waterhouse said the fact that the N. benthamiana variety from central Australia had doubled its seed size also opened the door for investigations into how N. benthamiana could be used commercially as a biofactory,
as seeds were an excellent place in which to make antibodies for pharmaceutical use. Researchers around the world can access Professor Waterhouse's open source website
to study the genomes of seven family members. Dr Bally and Professor Waterhouse have lodged a patent on their study (Organisms with Modified Growth Characteristics and Methods of Making Them) and a research paper,
The extremophile Nicotiana bethamiana has traded viral defence for early vigour, has been published in Nature Plant t
#Minuscule, flexible compound lenses magnify large fields of view Drawing inspiration from an insect's multifaceted eye,
University of Wisconsin-Madison engineers have created miniature lenses with vast range of vision. Their new approach created the first-ever flexible Fresnel zone plate microlenses with a wide field of view--a development that could allow everything from surgical scopes to security cameras to capture a broader perspective at a fraction of the size required by conventional lenses.
Led by Hongrui Jiang, professor of electrical and computer engineering at UW-Madison, the researchers designed lenses no larger than the head of a pin and embedded them within flexible plastic.
An array of the miniature lenses rolled into a cylinder can capture a panorama image covering a 170-degree field of view."
"We got the idea from compound eyes, "says Jiang, whose work was published in the Oct 30 issue of the journal Scientific Reports("Micro-Fresnel-Zone-Plate Array on Flexible Substrate for Large Field-of-view and Focus Scanning").
""We know that multiple lenses on a domed structure give a large field of view.""And the researchers can freely reconfigure the shape of the lens array,
Black silicon consists of clusters of microscopic vertical pillars, or nanowires. Incoming light bouncing between individual silicon nanowires cannot escape the complex structure,
making the material darker than dark. Rather than laying down layers of black silicon on top of a clear backdrop,
and etched silicon nanowires in the areas between aluminum rings. Then they seeped a polymer between the silicon nanowire pillars.
After the plastic support solidified they etched away the silicon backing, leaving bull's-eye patterned black silicon embedded in supple plastic.
This approach gave their lenses unprecedented crisp focusing capabilities, as well as the flexibility that enables them to capture a large field of view.
Jiang and his team--including postdoctoral scholar Mohammad J. Moghimi, graduate student Jayer Fernandes and recent graduate Aditi Kanhere--are exploring ways to integrate the lenses into existing optical detectors and directly incorporate silicon electronic components into the lenses themselves s
#Minuscule, flexible compound lenses magnify large fields of view Drawing inspiration from an insect's multifaceted eye,
University of Wisconsin-Madison engineers have created miniature lenses with vast range of vision. Their new approach created the first-ever flexible Fresnel zone plate microlenses with a wide field of view--a development that could allow everything from surgical scopes to security cameras to capture a broader perspective at a fraction of the size required by conventional lenses.
Led by Hongrui Jiang, professor of electrical and computer engineering at UW-Madison, the researchers designed lenses no larger than the head of a pin and embedded them within flexible plastic.
An array of the miniature lenses rolled into a cylinder can capture a panorama image covering a 170-degree field of view."
"We got the idea from compound eyes, "says Jiang, whose work was published in the Oct 30 issue of the journal Scientific Reports("Micro-Fresnel-Zone-Plate Array on Flexible Substrate for Large Field-of-view and Focus Scanning").
"Silicon nanowire towers make up dark regions of the flexible Fresnel zone lenses. Each individual lens resembles a bull-eye of alternating light and dark.
Arrays of lenses formed within a flexible polymer bend and stretch into different configurations. And the researchers can freely reconfigure the shape of the lens array,
Black silicon consists of clusters of microscopic vertical pillars, or nanowires. Incoming light bouncing between individual silicon nanowires cannot escape the complex structure,
making the material darker than dark. Bringing Bucky into focus, curved arrays of individual lenses allow small-scale sensors to perceive a broader picture.
The cylindrical arrangement shown in the schematic allowed researchers to resolve a 170-degree field of view.
and etched silicon nanowires in the areas between aluminum rings. Then they seeped a polymer between the silicon nanowire pillars.
After the plastic support solidified, they etched away the silicon backing, leaving bull's-eye patterned black silicon embedded in supple plastic.
This approach gave their lenses unprecedented crisp focusing capabilities, as well as the flexibility that enables them to capture a large field of view.
Jiang and his team--including postdoctoral scholar Mohammad J. Moghimi graduate student Jayer Fernandes and recent graduate Aditi Kanhere--are exploring ways to integrate the lenses into existing optical detectors and directly incorporate silicon electronic components into the lenses themselves s
#New low-cost battery could help store renewable energy Wind and solar energy projects are growing at a respectable clip.
But storing electric power for days when the air is still or when the sun goes down remains a challenge, largely due to cost.
Now researchers are developing a new battery that could bring the price of storage to more affordable levels.
They report their new battery that uses low-cost materials sodium and magnesium in ACS journal Chemistry of Materials("Efficient and Inexpensive Sodiummagnesium Hybrid Battery".
"A hybrid intercalation battery based on a sodium/magnesium (Na/Mg) dual salt electrolyte, metallic magnesium anode,
and a cathode based on Fes2 nanocrystals. ACS) Today, lithium-ion batteries are the storage technology of choice for many applications, from electric cars to smartphones.
And, it appears, saving up power for homes is next. For example, Tesla, the maker of luxury electric cars, is ambitiously expanding its lithium-ion technology to fill that niche
and has started already rolling out systems to homeowners in a pilot project. But the $3, 000 price tag for the pack itself plus installation costs put it out of reach for most customers.
To make larger-scale energy storage more accessible, Maksym V. Kovalenko and colleagues wanted to develop an affordable alternative to lithium-ion.
The researchers started with magnesium as the batterys safe inexpensive and high-energy density anode material and paired it with pyrite,
which is made of iron and sulfur, as the cathode. The electrolyte the electrically conducting component contains sodium and magnesium ions.
Testing showed that the resulting devices energy density was close to that of lithium-ion batteries. It could get an additional two-to threefold boost with further development of magnesium electrolytes.
And because its made with low-cost materials, it could one day help support grid-scale energy storage,
the researchers say a
#Novel'crumpling'of hybrid nanostructures increases SERS sensitivity By"crumpling"to increase the surface area of graphene-gold nanostructures,
researchers from the University of Illinois at Urbana-Champaign have improved the sensitivity of these materials,
opening the door to novel opportunities in electronics and optical sensing applications.""I believe that this work will benefit researchers in the area of surface plasmonics by providing a new strategy/design for enhancing the surface enhanced Raman spectroscopy (SERS) detection limit,
"explained Sungwoo Nam, an assistant professor of mechanical science and engineering at Illinois."This mechanical self-assembly strategy will enable a new class of 3d crumpled graphene-gold (Au) nanostructures.
The enhanced limit of detection will allow biomedical and environment monitoring of important molecules at high sensitivity by SERS."
"SERS substrates are used to analyze the composition of a mixture at the nanoscale for environmental analysis, pharmaceuticals, material sciences, art and archeological research, forensic science, drug detection, food quality analysis,
and single cell detection. Using a combination of gold and silver nanoparticles and Raman-active dyes,
SERS substrates also can target specific DNA and RNA sequences.""This work demonstrates the unique capability of micro-to-nanoscale topographies of the crumpled graphene-Au nanoparticles--higher density,
three-dimensional optically active materials--that are enhanced further by the formation of hot spots, bringing the nanoparticles closer,
"explained Juyoung Leem, a graduate student and first author of the study published in Nano Letters("Mechanically Self-Assembled, Three-dimensional Grapheneold Hybrid Nanostructures for Advanced Nanoplasmonic Sensors").
""We achieve a 3d crumpled graphene-Au hybrid structure by the delamination and buckling of graphene on a thermally activated, shrinking polymer substrate.
This process enables precise control and optimization of the size and spacing of integrated Au nanoparticles on crumpled graphene for higher SERS enhancement."
"According to Nam, the 3d crumpled graphene-Au nanostructure exhibits at least one order of magnitude higher SERS detection sensitivity than that of conventional, flat graphene-Au nanoparticles.
The hybrid structure is adapted further to arbitrary curvilinear structures for advanced, in situ, nonconventional, nanoplasmonic sensing applications."
"One of the key advantages of our platform is its ability to shrink and adapt to complex 3d surfaces,
a function that has not been demonstrated previously,"Nam stated. An earlier study by Nam's research group was the first to demonstrate graphene integration onto a variety of different microstructured geometries,
including pyramids, pillars, domes, inverted pyramids, and the 3d integration of gold nanoparticle/graphene hybrid structures r
#Facebook M Is trained and Monitored by Humans, Facebook Reveals Facebook has entered the virtual digital assistant space with a new service for its millions of Messenger users,
known as M. Facebook M is a personal assistant that will be integrated into the main messaging app, Facebook Messenger.
Using this new digital assistant, the users of this application will be able to search for information as well as complete different tasks without the need of manually doing them.
At the moment, Facebook reveals that this service is still in its trial stages and as of now
only a few hundreds of people have access to the service. If you are a resident of the San francisco bay area,
you will be lucky to be among the first persons to enjoy this new service on Facebook Messenger.
The company however revealed that the rest of the world will be receiving this service in the coming days.
This announcement was made public by the Vice president of Facebook messaging products David Marcus via his Facebook page.
According to him, this new M service is powered by artificial intelligence that is being trained and closely monitored by real humans.
Facebook M can complete the tasks on behalf of the userfacebook M brings something new to the virtual digital assistant space
a space that is vastly dominated by Siri from Apple and Google Now from you know where.
Even though the current AI-based applications are top performers in their respective niches, M steps in with more than just being a digital assistant.
If you have any task that you want performed online, Facebook M can do just that.
For instance, the application can be used to make purchases on your behalf, get gifts and deliver them to any person you want,
Google Now can only manage to provide you with a list of recommended gifts that you can buy for your friend.
Facebook M will actually find the list of items, place an order and get the gift delivered to the desired person.
Facebook M will be using humans to provide users with feedbackeven though Facebook M will be relying a lot on artificial intelligence,
it was noted that this intelligence is trained and supervised by humans. The humans, known as M Trainers, will be composed of non-Facebook employees
and their work will be to ensure that users get the best responses to their queries and on time.
The inclusion of humans in Facebook M is a rather confusing feat as most companies are working to eliminate
and replace the work once done by humans and automate it. It is expected however that Facebook will hire more and more M trainers as the service expands to global users of Messenger.
M is expected to drop its dedicated reliance on humans at some point in future after the service becomes smart enough.
As a result, the number of M trainers will be chopped as by then, the service will have been trained on how to work perfectly with the minimal human intervention possible.
It is also important to note that unlike Google Now and Cortana Facebook M will not be making use of data it has collected about you over the years.
The service will only be providing feedback based on the parameters provided by the user at that given moment.
It also won be possible for the users to know whether the solution was provided by a real human or by software.
Facebook M is free of any charge and it will come integrated within Facebook Messenger g
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