#A different type of 2-D semiconductor To the growing list of two-dimensional semiconductors, such as graphene, boron nitride,
you can now add hybrid organic-inorganic perovskites. However, unlike the other contenders, which are covalent semiconductors,
these 2d hybrid perovskites are ionic materials, which gives them special properties of their own. Researchers at the U s. Department of energy (DOE)' s Lawrence Berkeley National Laboratory (Berkeley Lab) have grown successfully atomically thin 2d sheets of organic-inorganic hybrid perovskites from solution.
The ultrathin sheets are of high quality large in area, and square-shaped. They also exhibited efficient photoluminescence, color-tunability,
and a unique structural relaxation not found in covalent semiconductor sheets.""We believe this is the first example of 2d atomically thin nanostructures made from ionic materials,
"says Peidong Yang, a chemist with Berkeley Lab's Materials sciences Division and world authority on nanostructures,
who first came up with the idea for this research some 20 years ago.""The results of our study open up opportunities for fundamental research on the synthesis
and characterization of atomically thin 2d hybrid perovskites and introduces a new family of 2d solution-processed semiconductors for nanoscale optoelectronic devices, such as field effect transistors and photodetectors."
"Yang, who also holds appointments with the University of California (UC) Berkeley and is a co-director of the Kavli Energy Nanoscience Institute (Kavli-ENSI),
is the corresponding author of a paper describing this research in the journal Science. The paper is titled"Atomically thin two-dimensional organic-inorganic hybrid perovskites."
"The lead authors are Letian Dou, Andrew Wong and Yi Yu, all members of Yang's research group.
Other authors are Minliang Lai, Nikolay Kornienko, Samuel Eaton, Anthony Fu, Connor Bischak, Jie Ma,
Traditional perovskites are typically metal-oxide materials that display a wide range of fascinating electromagnetic properties,
including ferroelectricity and piezoelectricity, superconductivity and colossal magnetoresistance. In the past couple of years, organic-inorganic hybrid perovskites have been processed solution into thin films
or bulk crystals for photovoltaic devices that have reached a 20-percent power conversion efficiency. Separating these hybrid materials into individual
freestanding 2d sheets through such techniques as spin-coating, chemical vapor deposition, and mechanical exfoliation has met with limited success. In 1994,
while a Phd student at Harvard university, Yang proposed a method for preparing 2d hybrid perovskite nanostructures
and passed it on to co-lead author Dou, a postdoctoral student in his research group.
a hybrid perovskite made from a blend of lead, bromine, nitrogen, carbon and hydrogen atoms.""Unlike exfoliation and chemical vapor deposition methods,
which normally produce relatively thick perovskite plates, we were able to grow uniform square-shaped 2d crystals on a flat substrate with high yield
and excellent reproducibility,"says Dou.""We characterized the structure and composition of individual 2d crystals using a variety of techniques
and found they have shifted a slightly band-edge emission that could be attributed to structural relaxation.
A preliminary photoluminescence study indicates a band-edge emission at 453 nanometers, which is shifted red slightly as compared to bulk crystals.
This suggests that color-tuning could be achieved in these 2d hybrid perovskites by changing sheet thickness as well as composition via the synthesis of related materials."
"The well-defined geometry of these square-shaped 2d crystals is the mark of high quality crystallinity,
and their large size should facilitate their integration into future devices.""With our technique, vertical and lateral heterostructures can also be achieved,
#Scientists discover new system for human genome editing A team including the scientist who first harnessed the revolutionary CRISPR-Cas9 system for mammalian genome editing has identified now a different CRISPR system with the potential for even simpler and more precise
genome engineering. In a study published in Cell, Feng Zhang and his colleagues at the Broad Institute of MIT and Harvard and the Mcgovern Institute for Brain Research at MIT,
and John van der Oost at Wageningen University, describe the unexpected biological features of this new system
and demonstrate that it can be engineered to edit the genomes of human cells.""This has dramatic potential to advance genetic engineering,
"said Eric Lander, Director of the Broad Institute and one of the principal leaders of the human genome project."
"The paper not only reveals the function of a previously uncharacterized CRISPR system, but also shows that Cpf1 can be harnessed for human genome editing
and has remarkable and powerful features. The Cpf1 system represents a new generation of genome editing technology."
"CRISPR sequences were described first in 1987 and their natural biological function was described initially in 2010 and 2011.
The application of the CRISPR-Cas9 system for mammalian genome editing was reported first in 2013, by Zhang and separately by George Church at Harvard.
In the new study, Zhang and his collaborators searched through hundreds of CRISPR systems in different types of bacteria,
searching for enzymes with useful properties that could be engineered for use in human cells. Two promising candidates were the Cpf1 enzymes from bacterial species Acidaminococcus and Lachnospiraceae,
The newly described Cpf1 system differs in several important ways from the previously described Cas9, with significant implications for research and therapeutics,
leaving'blunt ends'that often undergo mutations as they are rejoined. With the Cpf1 complex the cuts in the two strands are offset, leaving short overhangs on the exposed ends.
Cpf1 cuts far away from the recognition site, meaning that even if the targeted gene becomes mutated at the cut site,
it can likely still be re-cut, allowing multiple opportunities for correct editing to occur.
the Cpf1 system provides new flexibility in choosing target sites. Like Cas9, the Cpf1 complex must first attach to a short sequence known as a PAM,
This could be an advantage in targeting some genomes, such as in the malaria parasite as well as in humans."
including in cancer research, "said Levi Garraway, an institute member of the Broad Institute, and the inaugural director of the Joint Center for Cancer Precision Medicine at the Dana-Farber Cancer Institute, Brigham and Women's Hospital,
and the Broad Institute. Garraway was involved not in the research. Zhang, Broad Institute, and MIT plan to share the Cpf1 system widely.
As with earlier Cas9 tools, these groups will make this technology freely available for academic research via the Zhang lab's page on the plasmid-sharing-website Addgene
The Zhang lab also offers free online tools and resources for researchers through its website, http://www. genome-engineering. org.
These groups plan to offer licenses that best support rapid and safe development for appropriate and important therapeutic uses."
"Our goal is to develop tools that can accelerate research and eventually lead to new therapeutic applications.
with other enzymes that may be repurposed for further genome editing advances
#Cabozantinib improves survival in patients with advanced kidney cancer: Results from the METEOR trial Patients with advanced kidney cancer live for nearly twice as long without their disease progressing
if they are treated with cabozantinib, a drug that inhibits the action of tyrosine kinases--enzymes that function as an"on
"or"off"switch in many cellular processes, including cancer. In the second of two late-breaking presentations of research that is predicted to change the way kidney cancer patients are treated,
Professor Toni Choueiri will tell the presidential session of the 2015 European Cancer Congress 1,
about results from the first 375 patients out of a total of 658 patients recruited to the phase III clinical METEOR trial comparing cabozantinib with everolimus,
the current standard treatment for the disease. Analysis of results in July 2015 showed that the estimated median (average) progression-free survival time for patients with advanced clear cell kidney cancer,
randomised to receive cabozantinib, was 7. 4 months, while it was 3. 8 months for those receiving everolimus.
The objective response rate (the proportion of patients whose tumours shrank, assessed up to 17 months) was 21%for cabozantinib and 5%for everolimus.
The findings are published simultaneously with the ECC2015 presentation in the New england Journal of Medicine. 2 Prof Choueiri
who is Associate professor of Medicine at Harvard Medical school and Clinical Director and Kidney Cancer Center Director at The Lank Center for Genitourinary Oncology, Dana-Farber Cancer Institute,
since the results may change the standard of care in patients with advanced kidney cancer who have received prior standard therapy that targets the vascular endothelial growth factor receptor (VEGFR)."
"Although treatment with VEGFR-targeted drugs has been very effective in the first line of therapy for patients with advanced kidney cancer,
This has resulted in a significant reduction in the rate of disease progression or death in the cabozantinib arm as compared with the everolimus arm.
Regaining tumour control after prior targeted therapy may reduce symptoms related to kidney cancer and eventually help patients live longer."
"An early evaluation of overall survival from the ongoing METEOR trial has shown a strong trend indicating that survival may be improved in patients receiving cabozantinib compared to standard therapy.
when the data have matured further with longer follow up of the patient population. Overall, these results should give new hope to patients diagnosed with advanced kidney cancer as cabozantinib may become a new treatment option."
"Clear cell kidney cancer (or renal cell carcinoma) is one of the commonest kidney cancers--70-80%of kidney cancer patients have this type.
If it is caught early, the prognosis is good; 81%of patients with stage I disease, in which the tumour is confined to the kidney,
survive for at least five years. However, when it has advanced, the prognosis is poor, with only around eight percent of patients with stage IV disease surviving for five years.
Patients recruited to the METEOR clinical trial, which started in June 2013, were randomised to receive either 60 mg a day of cabozantinib in tablet form,
or 10 mg a day of everolimus, also in tablet form. Their disease had to have progressed within six months of receiving prior treatment with VEGFR tyrosine kinase inhibitor (TKI) therapy.
The METEOR trial is also evaluating the safety of the treatment. The incidence of serious side effects was similar for both drugs
and discontinuation of treatment due to side effects occurred in 9. 1%of cabozantinib and 10%of everolimus patients.
%shortness of breath (3. 7%)and pneumonia (3. 7%).Prof Choueiri said:""The METEOR results are important from a clinical and scientific point of view.
or resistance to standard therapies is critical for improving long-term outcome for our patients with advanced kidney cancer.
Further studies include a randomised phase II study of cabozantinib versus standard of care with sunitinib as a first treatment for advanced renal cell cancer.
Combinations with other emerging therapies, such as agents boosting the immune system, are of interest and an early stage clinical trial combining cabozantinib with immune checkpoint inhibitors has been initiated in urological cancers,
including patients with kidney cancer.""The trial has stopped recruiting patients and researchers are hoping that cabozantinib may become available to patients with advanced kidney cancer some time in 2016.
In the USA, the Food and Drug Administration (FDA) has designated it as a breakthrough therapy,
which may allow expedited development of the drug. Professor Peter Naredi, the ECCO scientific co-chair of the Congress,
who was involved not in the research, commented:""I am excited over the advances in treatment of renal cell carcinoma that we are at present.
The results of the METEOR study are remarkable and most likely will be practice changing. This, together with the report of the Checkmate 025 study, are definitely among the highlights of this congress."
"The other late-breaking presentation in the presidential session will be made by Professor Padmanee Sharma, who will be reporting results from the Checkmate 025 randomised phase III trial of nivolumab versus everolimus in advanced kidney cancer r
#Novel prosthetic heart valve developed for treatment of severe heart disorder A team of researchers from the National University of Singapore (NUS) has developed a novel prosthetic heart valve, known as Velox,
which can be implanted through a small incision for the treatment of a serious heart valve disorder called mitral regurgitation.
This is a condition in which the mitral valve on the left side of the heart does not close properly.
The device is particularly beneficial to patients who are of high surgical risk or are unsuitable for existing clinical interventions.
and does not close all the way, blood flows backward into the upper heart chamber (atrium) from the lower chamber as it contracts.
and this may lead to congestive heart failure or it may worsen an existing heart failure. Pioneered by Associate professor Leo Hwa Liang from the Department of Biomedical engineering at NUS'Faculty of engineering
and Dr Jimmy Hon from the Department of Surgery at the NUS Yong Loo Lin School of medicine, this novel invention addresses a clinical gap in the current treatment of mitral valve regurgitation.
This research project is supported by the Medical Engineering Research & Commercialization Initiative (MERCI) under the Department of Surgery of the NUS Yong Loo Lin School of medicine.
Other members of the team include Mr Kenneth Chan Zhi Wei, a current Biomedical engineering Masters student who is working on the design of the device under the supervision of Assoc Prof Leo,
and Dr Elynn Phang Hui Qun of MERCI, who is managing the commercialisation of the invention.
or are suffering from multiple chronic diseases are not suitable for the treatment. Although current mitral valve interventions delivered via a small incision through the skin could be a viable alternative treatment
therefore be a viable option for patients who are not suitable for surgeries or the standard treatment.
How Velox works The tiny device comprises a prosthetic heart valve made of pericardial tissue"stitched"within a self-expanding
polymer coated nickel-titanium (nitinol) alloy stent frame specially designed to prevent leakage. To implant the device,
the prosthetic valve is compressed to the thickness of a pencil and loaded into a catheter.
The catheter is inserted into the patient through a small incision made either at the leg
The catheter will then be used to send the device to the patient's diseased mitral valve.
This transcatheter valve offers palliative treatment for the patients who were denied surgery, especially those with multiple co-morbidities."
"Dr Hon is also a Senior Consultant at the Department of Cardiac, Thoracic and Vascular Surgery, National University Heart Centre, Singapore.
Further studies and commericalization Building on the encouraging results from the earlier phases of the project, the team is now refining the design of the existing device.
The team plans to conduct in vivo studies to acquire data on the technical performance of the device.
They hope to work with medical technology companies to commercialise their invention to benefit patients soon n
by a team at the University of New south wales (UNSW) in Sydney appears in the international journal Nature."
"said team leader Andrew Dzurak, Scientia Professor and Director of the Australian National Fabrication Facility at UNSW."
"We've demonstrated a two-qubit logic gate--the central building block of a quantum computer--and, significantly, done it in silicon.
Because we use essentially the same device technology as existing computer chips, we believe it will be much easier to manufacture a full-scale processor chip than for any of the leading designs,
which rely on more exotic technologies.""This makes the building of a quantum computer much more feasible,
since it is based on the same manufacturing technology as today's computer industry, "he added. The advance represents the final physical component needed to realise the promise of super-powerful silicon quantum computers,
which harness the science of the very small--the strange behaviour of subatomic particles--to solve computing challenges that are beyond the reach of even today's fastest supercomputers.
In classical computers, data is rendered as binary bits, which are always in one of two states:
0 or 1. However, a quantum bit (or'qubit')can exist in both of these states at once, a condition known as a superposition.
A qubit operation exploits this quantum weirdness by allowing many computations to be performed in parallel (a two-qubit system performs the operation on 4 values, a three-qubit system on 8, and so on."
--and thereby create a logic gate--using silicon. But the UNSW team--working with Professor Kohei M. Itoh of Japan's Keio University--has done just that for the first time.
The result means that all of the physical building blocks for a silicon-based quantum computer have now been constructed successfully
allowing engineers to finally begin the task of designing and building a functioning quantum computer. A key advantage of the UNSW approach is that they have reconfigured the'transistors'that are used to define the bits in existing silicon chips,
and turned them into qubits.""The silicon chip in your smartphone or tablet already has around one billion transistors on it,
with each transistor less than 100 billionths of a metre in size,"said Dr Menno Veldhorst,
a UNSW Research Fellow and the lead author of the Nature paper.""We've morphed those silicon transistors into quantum bits by ensuring that each has only one electron associated with it.
We then store the binary code of 0 or 1 on the'spin'of the electron,
which is associated with the electron's tiny magnetic field, "he added. Dzurak noted that that the team had patented recently a design for a full-scale quantum computer chip that would allow for millions of our qubits,
all doing the types of calculations that we've just experimentally demonstrated.""He said that a key next step for the project is to identify the right industry partners to work with to manufacture the full-scale quantum processor chip.
Such a full-scale quantum processor would have major applications in the finance, security and healthcare sectors, allowing the identification
and development of new medicines by greatly accelerating the computer-aided design of pharmaceutical compounds (and minimizing lengthy trial and error testing);
the development of new, lighter and stronger materials spanning consumer electronics to aircraft; and faster information searching through large databases s
#Liquid cooling moves onto the chip for denser electronics Using microfluidic passages cut directly into the backsides of production field-programmable gate array (FPGA) devices,
Georgia Institute of technology researchers are putting liquid cooling right where it's needed the most--a few hundred microns away from where the transistors are operating.
Combined with connection technology that operates through structures in the cooling passages, the new technologies could allow development of denser
and more powerful integrated electronic systems that would no longer require heat sinks or cooling fans on top of the integrated circuits.
Working with popular 28-nanometer FPGA devices made by Altera Corp. the researchers have demonstrated a monolithically-cooled chip that can operate at temperatures more than 60 percent below those of similar air-cooled chips.
In addition to more processing power, the lower temperatures can mean longer device life and less current leakage.
The cooling comes from simple deionized water flowing through microfluidic passages that replace the massive air-cooled heat sinks normally placed on the backs of chips."
"We believe we have eliminated one of the major barriers to building high-performance systems that are more compact
and energy efficient,"said Muhannad Bakir, an associate professor and ON Semiconductor Junior Professor in the Georgia Tech School of Electrical and Computer engineering."
"We have eliminated the heat sink atop the silicon die by moving liquid cooling just a few hundred microns away from the transistors.
We believe that reliably integrating microfluidic cooling directly on the silicon will be a disruptive technology for a new generation of electronics."
"Supported by the Defense Advanced Research Projects Agency (DARPA), the research is believed to be the first example of liquid cooling directly on an operating high-performance CMOS chip.
Details of the research were presented on September 28 at the IEEE Custom Integrated circuits Conference in San jose,
Calif. Liquid cooling has been used to address the heat challenges facing computing systems whose power needs have been increasing.
However, existing liquid cooling technology removes heat using cold plates externally attached to fully packaged silicon chips--adding thermal resistance and reducing the heat-rejection efficiency.
Bakir and graduate student Thomas Sarvey removed the heat sink and heat-spreading materials from the backs of stock Altera FPGA chips.
They then etched cooling passages into the silicon, incorporating silicon cylinders approximately 100 microns in diameter to improve heat transmission into the liquid.
A silicon layer was placed then over the flow passages, and ports were attached for the connection of water tubes.
Virginia--a liquid-cooled FPGA was operated using a custom processor architecture provided by Altera. With a water inlet temperature of approximately 20 degrees Celsius and an inlet flow rate of 147 milliliters per minute
Sudhakar Yalamanchili, a professor in the Georgia Tech School of Electrical and Computer engineering and one of the research group's collaborators, joined the team for the DARPA demonstration to discuss electrical-thermal co-design."
"This may open the door to stacking multiple chips, potentially multiple FPGA chips or FPGA chips with other chips that are high in power consumption.
We are seeing a significant reduction in the temperature of these liquid-cooled chips.""The research team chose FPGAS for their test
because they provide a platform to test different circuit designs, and because FPGAS are common in many market segments,
including defense. However, the same technology could also be used to cool CPUS, GPUS and other devices such as power amplifiers,
Bakir said. In addition to improving overall cooling, the system could reduce hotspots in circuits by applying cooling much closer to the power source.
Eliminating the heat sink could allow more compact packaging of electronic devices --but only if electrical connection issues are addressed also.
Graduate student Hanju Oh, co-advised with College of Engineering Dean Gary May, fabricated high aspect ratio copper vias through the silicon columns, reducing the capacitance of the connections that would carry signals between chips in an array."
"The moment you start thinking about stacking the chips, you need to have copper vias to connect them,
"Bakir said.""By bringing system components closer together, we can reduce interconnect length and that will lead to improvements in bandwidth density and reductions in energy use."
"The cooling research was funded by DARPA's Microsystems Technology Office, through the ICECOOL program. At Georgia Tech, DARPA funds two major cooling and system integration projects, one called STAECOOL directed by George W. Woodruff School of Mechanical engineering Professor Yogendra Joshi,
and the other, called Supercool, that is directed by Bakir. In collaboration with the STAECOOL effort, Bakir and Joshi,
along with Professors Andrei Fedorov and Suresh Sitaraman from the School of Mechanical engineering, developed a thermal design vehicle to emulate challenging power maps to test the benefits of microfluidic cooling."
"Future high-performance semiconductor electronics will be increasingly dominated by thermal budget and ability to remove heat. The embedded microfluidic channels provide an intriguing option to remove heat from future microelectronics systems."
"This research was supported by DARPA-MTO; the contents of the news release are the responsibility of the authors
Ion channels are typically about 1 nanometer wide; by maintaining the right balance of ions, they keep cells healthy and stable.
Each graphene pore is less than 2 nanometers wide, making them among the smallest pores through
or selectivities,"says Rohit Karnik, an associate professor of mechanical engineering at MIT. Karnik says graphene nanopores could be useful as sensors--for instance,
detecting ions of mercury, potassium, or fluoride in solution. Such ion-selective membranes may also be useful in mining:
In the future, it may be possible to make graphene nanopores capable of sifting out trace amounts of gold ions from other metal ions, like silver and aluminum.
Karnik and former graduate student Tarun Jain, along with Benjamin Rasera, Ricardo Guerrero, Michael Boutilier, and Sean O'Hern from MIT and Juan-carlos Idrobo from Oak ridge National Laboratory, publish their results in the journal Nature Nanotechnology.
Dynamic personality In living cells, the diversity of ion channels may arise from the size and precise atomic arrangement of the channels,
"When nanopores get smaller than the hydrated size of the ion, then you start to see interesting behavior emerge,
The researchers used the process to generate nanometer-sized pores in various sheets of graphene,
The researchers then isolated individual pores by placing each graphene sheet over a layer of silicon nitride that had been punctured by an ion beam
and then through the larger silicon nitride hole. The group measured flows of five different salt ions through several graphene sheet setups by applying a voltage and measuring the current flowing through the pores.
Based on the model, they found that the diameter of many of the pores was below 1 nanometer,
Knowing this, researchers may one day be able to tailor pores at the nanoscale to create ion-specific membranes for applications such as environmental sensing and trace metal mining."
Medical researchers have developed now a highly effective in vitro technique for producing light sensitive retina cells from human embryonic stem cells.
"Cone transplant represents a therapeutic solution for retinal pathologies caused by the degeneration of photoreceptor cells,
offering hope that treatments may be developed for currently non-curable degenerative diseases, like Stargardt disease and ARMD."
ARMD is in fact the greatest cause of blindness amongst people over the age of 50
this accelerated aging of the retina affects nearly one in four. People with ARMD gradually lose their perception of colours
write, watch television or even recognize a face. ARMD is due to the degeneration of the macula
This degeneration is caused by the destruction of the cones and cells in the retinal pigment epithelium (RPE),
and less effective--waste accumulates, forming deposits.""Differentiating RPE cells is quite easy. But in order to undertake a complete therapy,
we need neuronal tissue that links all RPE cells to the cones. That is much more complex to develop,
Indeed, bioinformatic analysis led him to predict the existence of a mysterious protein: COCO, a"recombinational"human molecule that is normally expressed within photoreceptors during their development.
In 2001, he launched his laboratory at Maisonneuve-Rosemont Hospital and immediately isolated the molecule.
Beyond the clinical applications, Professor Bernier's findings could enable the modelling of human retinal degenerative diseases through the use of induced pluripotent stem cells,
offering the possibility of directly testing potential avenues for therapy on the patient's own tissues s
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