One step closer to a single-molecule device

Kurzweil AI - 1 hour 37 min ago

Molecular diode (credit: Columbia Engineering)

Columbia Engineering researchers have created the first single-molecule diode — the ultimate in miniaturization for electronic devices — with potential for real-world applications in electronic systems.

The diode that has a high (>250) rectification and a high “on” current (~ 0.1 microamps), says Latha Venkataraman, associate professor of applied physics. “Constructing a device where the active elements are only a single molecule … which has been the ‘holy grail’ of molecular electronics, represents the ultimate in functional miniaturization that can be achieved for an electronic device,” he said.

With electronic devices becoming smaller every day, the field of molecular electronics has become ever more critical in solving the problem of further miniaturization, and single molecules represent the limit of miniaturization. The idea of creating a single-molecule diode was suggested by Arieh Aviram and Mark Ratner who theorized in 1974 that a molecule could act as a rectifier, a one-way conductor of electric current.

The future of miniaturization

Researchers have since been exploring the charge-transport properties of molecules. They have shown that single-molecules attached to metal electrodes (single-molecule junctions) can be made to act as a variety of circuit elements, including resistors, switches, transistors, and, indeed, diodes. They have learned that it is possible to see quantum mechanical effects, such as interference, manifest in the conductance properties of molecular junctions.

Since a diode acts as an electricity valve, its structure needs to be asymmetric so that electricity flowing in one direction experiences a different environment than electricity flowing in the other direction. To develop a single-molecule diode, researchers have simply designed molecules that have asymmetric structures.

“While such asymmetric molecules do indeed display some diode-like properties, they are not effective,” explains Brian Capozzi, a PhD student working with Venkataraman and lead author of the paper. “A well-designed diode should only allow current to flow in one direction …  and it should allow a lot of current to flow in that direction. Asymmetric molecular designs have typically suffered from very low current flow in both ‘on’ and ‘off’ directions, and the ratio of current flow in the two has typically been low. Ideally, the ratio of ‘on’ current to ‘off’ current, the rectification ratio, should be very high.”

To overcome the issues associated with asymmetric molecular design, Venkataraman and her colleagues — Chemistry Assistant Professor Luis Campos’ group at Columbia and Jeffrey Neaton’s group at the Molecular Foundry at UC Berkeley — focused on developing an asymmetry in the environment around the molecular junction. They created an environmental asymmetry through a rather simple method: they surrounded the active molecule with an ionic solution and used gold metal electrodes of different sizes to contact the molecule.

Avoiding quantum-mechanical effects

Their results achieved rectification ratios as high as 250 — 50 times higher than earlier designs. The “on” current flow in their devices can be more than 0.1 microamps, which, Venkataraman notes, is a lot of current to be passing through a single-molecule. And, because this new technique is so easily implemented, it can be applied to all nanoscale devices of all types, including those that are made with graphene electrodes.

“It’s amazing to be able to design a molecular circuit, using concepts from chemistry and physics, and have it do something functional,” Venkataraman says. “The length scale is so small that quantum mechanical effects are absolutely a crucial aspect of the device. So it is truly a triumph to be able to create something that you will never be able to physically see and that behaves as intended.”

She and her team are now working on understanding the fundamental physics behind their discovery, and trying to increase the rectification ratios they observed, using new molecular systems.

The study, described in a paper published today (May 25) in Nature Nanotechnology, was funded by the National Science Foundation, the Department of Energy, and the Packard Foundation.

Categories: Science

Fly-catching robot speeds biomedical research

Kurzweil AI - 2 hours 2 min ago

A fruit fly hangs unharmed at the end of the robot’s suction tube. The robot uses machine vision to inspect and analyze the captured fly. (credit: Stanforf Bio-X)

Stanford Bio-X scientists have created a robot that speeds and extends biomedical research with a common laboratory organism — fruit flies (Drosophila).

The robot can visually inspect awake flies and carry out behavioral experiments that were impossible with anesthetized flies. The work is described today (May 25) in the journal Nature Methods.

“Robotic technology offers a new prospect for automated experiments and enables fly researchers to do several things they couldn’t do previously,” said research team leader Mark Schnitzer, an associate professor of biology and of applied physics.

“For example, it can do studies with large numbers of flies inspected in very precise ways.” The group did one study of 1,000 flies in 10 hours, a task that would have taken much longer for even a highly skilled human.

Zap, you’re part of an experiment

When the robot’s fly-snatching apparatus is ready to grab a fly, it flashes a brief infrared blast of light that is invisible to the fly. The light reflects off its thorax, indicating the precise location of each fly and allowing the robot to recognize each individual fly by its reflection pattern. Then, a tiny, narrow suction tube strikes one of the illuminated thoraxes, painlessly sucking onto the fly and lifting it up.

Once the fly is attached, the robot uses machine vision to analyze the fly’s physical attributes, sort the flies by male and female, and even carry out a microdissection to reveal the fly’s minuscule brain. In one experiment, the robot’s machine vision was able to differentiate between two strains of flies so similar they are indistinguishable to the human eye.

Speeding disease research

All this is good news to the legion of graduate students who still spend hours a day looking at flies under a microscope as part of work that continues to uncover mechanisms in human aging, cancer, diabetes and a range of other diseases.

Although flies and humans have obvious differences, in many cases our cells and organs behave in similar ways and it is easier to study those processes in flies than in humans. The earliest information about how radiation causes gene mutations came from fruit flies, as did an understanding of our daily sleep/waking rhythms. And many of the molecules that are now famous for their roles in regulating how cells communicate were originally discovered by scientists hunched over microscopes staring at the unmoving bodies of anesthetized flies.

Now, that list of fruit fly contributions can be expended to include behavioral studies, previously impossible because the humans carrying out the analysis can neither see fly behaviors clearly nor distinguish between individuals.

In their paper, Schnitzer and his team had the robot pick up a fly and carry it to a trackball. Once there, they exposed the fly to different smells and could record how the fly behaved — racing along the trackball to get closer or attempting to turn away.

The work was funded by the W.M. Keck Foundation, the Stanford Bio-X program, an NIH Director’s Pioneer Award, and the Stanford-NIBIB Training Program in Biomedical Imaging Instrumentation.

Categories: Science

Converting blood stem cells to sensory neural cells to predict and treat pain

Kurzweil AI - 2 hours 37 min ago

McMaster University scientists have discovered how to make adult sensory neurons from a patient’s blood sample to measure pain (credit: McMaster University

Stem-cell scientists at McMaster University have developed a way to directly convert adult human blood cells to sensory neurons, providing the first objective measure of how patients may feel things like pain, temperature, and pressure, the researchers reveal in an open-access paper in the journal Cell Reports.

Currently, scientists and physicians have a limited understanding of the complex issue of pain and how to treat it. “The problem is that unlike blood, a skin sample or even a tissue biopsy, you can’t take a piece of a patient’s neural system,” said Mick Bhatia, director of the McMaster Stem Cell and Cancer Research Institute and research team leader. “It runs like complex wiring throughout the body and portions cannot be sampled for study.

“Now we can take easy to obtain blood samples, and make the main cell types of neurological systems in a dish that is specialized for each patient,” said Bhatia. “We can actually take a patient’s blood sample, as routinely performed in a doctor’s office, and with it we can produce one million sensory neurons, [which] make up the peripheral nerves. We can also make central nervous system cells.”

Testing pain drugs

The new technology has “broad and immediate applications,” said Bhatia: It allows researchers to understand disease and improve treatments by asking questions such as: Why is it that certain people feel pain versus numbness? Is this something genetic? Can the neuropathy that diabetic patients experience be mimicked in a dish?

It also paves the way for the discovery of new pain drugs that don’t just numb the perception of pain. Bhatia said non-specific opioids used for decades are still being used today. “If I was a patient and I was feeling pain or experiencing neuropathy, the prized pain drug for me would target the peripheral nervous system neurons, but do nothing to the central nervous system, thus avoiding addictive drug side effects,” said Bhatia.

“Until now, no one’s had the ability and required technology to actually test different drugs to find something that targets the peripheral nervous system, and not the central nervous system, in a patient-specific, or personalized manner.”

A patient time machine 

Bhatia’s team also successfully tested their process with cryopreserved (frozen) blood. Since blood samples are taken and frozen with many clinical trials, this give them “almost a bit of a time machine” to run tests on neurons created from blood samples of patients taken in past clinical trials, where responses and outcomes have already been recorded.

In the future, the process may have prognostic (predictive diagnostic) potential, explained Bhatia: one might be able to look at a patient with Type 2 Diabetes and predict whether they will experience neuropathy, by running tests in the lab using their own neural cells derived from their blood sample.

“This bench-to-bedside research is very exciting and will have a major impact on the management of neurological diseases, particularly neuropathic pain,” said Akbar Panju, medical director of the Michael G. DeGroote Institute for Pain Research and Care, a clinician and professor of medicine.

“This research will help us understand the response of cells to different drugs and different stimulation responses, and allow us to provide individualized or personalized medical therapy for patients suffering with neuropathic pain.”

This research was supported by the Canadian Institutes of Health Research, Ontario Institute of Regenerative Medicine, Marta and Owen Boris Foundation, J.P. Bickell Foundation, the Ontario Brain Institute, and Brain Canada.

Abstract of Single Transcription Factor Conversion of Human Blood Fate to NPCs with CNS and PNS Developmental Capacity

The clinical applicability of direct cell fate conversion depends on obtaining tissue from patients that is easy to harvest, store, and manipulate for reprogramming. Here, we generate induced neural progenitor cells (iNPCs) from neonatal and adult peripheral blood using single-factor OCT4 reprogramming. Unlike fibroblasts that share molecular hallmarks of neural crest, OCT4 reprogramming of blood was facilitated by SMAD+GSK-3 inhibition to overcome restrictions on neural fate conversion. Blood-derived (BD) iNPCs differentiate in vivo and respond to guided differentiation in vitro, producing glia (astrocytes and oligodendrocytes) and multiple neuronal subtypes, including dopaminergic (CNS related) and nociceptive neurons (peripheral nervous system [PNS]). Furthermore, nociceptive neurons phenocopy chemotherapy-induced neurotoxicity in a system suitable for high-throughput drug screening. Our findings provide an easily accessible approach for generating human NPCs that harbor extensive developmental potential, enabling the study of clinically relevant neural diseases directly from patient cohorts.

Categories: Science

Sniffing and Tracking Wearable Tech and Smartphones

Slashdot - 3 hours 35 min ago
An anonymous reader writes: Senior researcher Scott Lester at Context Information Security has shown how someone can easily monitor and record Bluetooth Low Energy signals transmitted by many mobile phones, fitness monitors, and iBeacons. The findings have raised concerns about the privacy and confidentiality wearable devices may provide. “Many people wearing fitness devices don’t realize that they are broadcasting constantly and that these broadcasts can often be attributed to a unique device,” said Scott says. “Using cheap hardware or a smartphone, it could be possible to identify and locate a particular device – that may belong to a celebrity, politician or senior business executive – within 100 meters in the open air. This information could be used for social engineering as part of a planned cyber attack or for physical crime by knowing peoples’ movements.” The researchers have even developed an Android app that scans, detects and logs wearable devices.

Read more of this story at Slashdot.

Categories: Science

Large Amount of Star Citizen Art Assets Leaked

Slashdot - Mon, 25/05/2015 - 11:47pm
jones_supa writes: A huge batch of work-in-progress assets for Star Citizen have leaked to the public. An unknown person, likely connected with Cloud Imperium Games in some way, provided a link to the 48 gigabytes of content. The link has now been taken down, but as we know, it's hard to remove material from Internet after once put there. Being a CryEngine game, it has been suggested that it might be possible to view some of the assets using CryEngine development tools. Leaks are always quite the conundrum with the opportunities they present to curious fans and competitor companies, but can also be very depressing for the developers and publisher of the game.

Read more of this story at Slashdot.

Categories: Science

Leaked Document Shows Europe Would Fight UK Plans To Block Porn

Slashdot - Mon, 25/05/2015 - 10:55pm
Mark Wilson writes: Before the UK elections earlier in the month, David Cameron spoke about his desire to clean up the internet. Pulling — as he is wont to do — on parental heartstrings, he suggested that access to porn on computers and mobiles should be blocked by default unless users specifically requested access to it. This opt-in system was mentioned again in the run-up to the election as Secretary of State for Culture, Media and Sport, Sajid Javid assured peopled that the party "will age restrict online porn". But it's not quite that simple. There is the small problem of Europe. A leaked EU Council document shows that plans are afoot to stop Cameron's plans in its tracks — and with the UK on the verge of trying to debate a better deal for itself within Europe, the Prime Minister is not in a particularly strong position for negotiating on the issue. Cameron has a fight on his hands, it seems, if he wants to deliver on his promise that "we need to protect our children from hardcore pornography". Documents seen by The Sunday Times reveal that the EU could make it illegal for ISPs and mobile companies to automatically block access to obscene material. Rather than implementing a default block on pornography, the Council of the European Union believes that users should opt in to web filtering and be able to opt out again at any time; this is precisely the opposite to the way Cameron would like things to work.

Read more of this story at Slashdot.

Categories: Science

Sex-Switched Mosquitoes May Help In Fight Against Diseases

Slashdot - Mon, 25/05/2015 - 10:03pm
cstacy writes: Only the female mosquitoes bite and transmit viral diseases such as Dengue Fever. Scientists have finally discovered the elusive genetic switch called Nix, that determines the sex of these blood sucking insects, and hope to selectively eliminate females to control the spread of diseases. "Nix provides us with exciting opportunities to harness mosquito sex in the fight against infectious diseases because maleness is the ultimate disease-refractory trait," explained Zhijian Jake Tu, an affiliate of the Fralin Life Science Institute and a biochemistry professor from Virginia Tech's College of Agriculture and Life Sciences.

Read more of this story at Slashdot.

Categories: Science

Appropriate duration of dual antiplatelet therapy still unclear

Science Daily - Mon, 25/05/2015 - 9:56pm
A systematic review of published evidence does little to clarify the appropriate duration of dual antiplatelet therapy following drug eluting stent placement. The evidence suggests that longer duration therapy decreases the risk for myocardial infarction, but increases the risk for major bleeding events, and may provide a slight increase in mortality.
Categories: Science

Hackers Can Track Subway Riders' Movements By Smartphone Accelerometer

Slashdot - Mon, 25/05/2015 - 9:15pm
Patrick O'Neill writes: Tens of millions of daily subway riders around the world can be tracked through their smartphones by a new attack, according to research from China's Nanjing University. The new attack even works underground and doesn't utilize GPS or cell networks. Instead, the attacker steals data from a phone's accelerometer. Because each subway in the world has a unique movement fingerprint, the phone's motion sensor can give away a person's daily movements with up to 92% accuracy.

Read more of this story at Slashdot.

Categories: Science

Galapagos Island Volcano Erupts After 33 Years, Threatening Fragile Ecosystem

Slashdot - Mon, 25/05/2015 - 8:25pm
An anonymous reader writes: Wolf volcano in the Galapagos islands has erupted for the first time in more than 30 years, sending lava flowing down its slopes and potentially threatening the world's only colony of pink iguanas. The Galapagos National Park says that currently there is no risk to tourism operations, but the Environment Ministry is notifying tourist operators to take precautions. A tourist boat passing by took an amazing picture of the eruption.

Read more of this story at Slashdot.

Categories: Science

Google's Diversity Chief: Mamas Don't Let Their Baby Girls Grow Up To Be Coders

Slashdot - Mon, 25/05/2015 - 7:37pm
theodp writes: Explaining the reasons for its less-than-diverse tech workforce, Google fingered bad parenting for its lack of women techies. From the interview with Google Director of Diversity and Inclusion Nancy Lee: "Q. What explains the drop [since 1984] in women studying computer science? A. We commissioned original research that revealed it's primarily parents' encouragement, and perception and access. Parents don't see their young girls as wanting to pursue computer science and don't steer them in that direction. There's this perception that coding and computer science is ... a 'brogrammer' culture for boys, for games, for competition. There hasn't been enough emphasis on the power computing has in achieving social impact. That's what girls are interested in. They want to do things that matter." While scant on details, the Google study's charts appear to show that, overall, fathers encourage young women to study CS more than mothers. Google feels that reeducation is necessary. "Outreach programs," advises Google, "should include a parent education component, so that parents learn how to actively encourage their daughters."

Read more of this story at Slashdot.

Categories: Science

Ovarian cancer-specific markers set the stage for early diagnosis, personalized treatments

Science Daily - Mon, 25/05/2015 - 7:11pm
Six mRNA isoforms (bits of genetic material) produced by ovarian cancer cells but not normal cells have been identified by scientists, opening up the possibility that they could be used to diagnose early-stage ovarian cancer. What's more, several of the mRNA isoforms code for unique proteins that could be targeted with new therapeutics.
Categories: Science

New way of preventing diabetes-associated blindness

Science Daily - Mon, 25/05/2015 - 7:11pm
Reporting on their study with lab-grown human cells, researchers say that blocking a second blood vessel growth protein, along with one that is already well-known, could offer a new way to treat and prevent a blinding eye disease caused by diabetes.
Categories: Science

Largest Eruption In the Known Universe Is ~100 Times the Size of Milky Way

Slashdot - Mon, 25/05/2015 - 6:51pm
StartsWithABang writes: At the center of almost every galaxy is a supermassive black hole (SMBH); at the center of almost every cluster is a supermassive galaxy with some of the largest SMBHs in the Universe. And every once in a while, a galactocentric black hole will become active, emitting tremendous amounts of radiation out into the Universe as it devours matter. This radiation can cut across the spectrum, from the X-ray down to the radio. At the heart of MS 0735.6+7421, there's a >10^10 solar mass black hole that appears to have been active for hundreds of millions of years, something unheard of!

Read more of this story at Slashdot.

Categories: Science

Privacy Behaviors Changed Little After Snowden

Slashdot - Mon, 25/05/2015 - 6:04pm
An anonymous reader writes: An article in Communications of the ACM takes a look at how Edward Snowden's revelations about government surveillance have changed privacy behaviors across the world. The results are fairly disappointing. While the news that intelligence agencies were trawling data from everyday citizens sparked an interest in privacy, it was small, and faded quickly. Even through media coverage has continued for a long time after the initial reports, public interest dropped back to earlier levels long ago. The initial interest spike was notably less than for other major news events. Privacy-enhancing behaviors experienced a small surge, but that too failed to impart any long-term momentum. The author notes that the spike in interest "following the removal of privacy-enhancing functions in Facebook, Android, and Gmail" was stronger than the reaction to the government's privacy-eroding actions.

Read more of this story at Slashdot.

Categories: Science

Patterns of brain activity reorganize visual perception during eye movements

Science Daily - Mon, 25/05/2015 - 5:23pm
Oscillations of activity observed in the brain could have a role in resetting the sensitivity of neurons after eye movements. Further results suggest these waves could also have a role in supporting the brain's representation of space.
Categories: Science

Frailer older patients at higher risk of readmission or death after discharge from hospital

Science Daily - Mon, 25/05/2015 - 5:23pm
Frailer older patients are at higher risk of readmission to hospital or death within 30 days after discharge from a general internal medicine ward, but health care professionals can assess who is at risk using the Clinical Frailty Scale, according to a study.
Categories: Science

Mozilla Drops $25 Smartphone Plans, Will Focus On Higher Quality Devices

Slashdot - Mon, 25/05/2015 - 5:18pm
An anonymous reader writes: When Mozilla developed Firefox OS, its goal was not to provide the best smartphone experience, but to provide a "good enough" smartphone experience for a very low price. Unfortunately, these cheap handsets failed to make a dent in the overall smartphone market, and the organization is now shifting its strategy to start producing a better experience for better devices. CEO Chris Beard said, "If you are going to try to play in that world, you need to offer something that is so valuable that people are willing to give up access to the broader ecosystem. In the mass market, that's basically impossible." Of course, when moving to the midrange smartphone market, or even the high end, there's still plenty of competition, so the new strategy may not work any better. However, they've hinted at plans to start supporting Android apps, which could help them play catch-up. Beard seems fixated on this new goal: "We won't allow ourselves to be distracted, and we won't expand to new segments until significant traction is demonstrated." He adds, "We will build products that feel like Mozilla."

Read more of this story at Slashdot.

Categories: Science

D.C. Police Detonate Man's 'Suspicious' Pressure Cooker

Slashdot - Mon, 25/05/2015 - 4:28pm
An anonymous reader writes: Yesterday evening in Washington D.C., police officers on routine patrol spotted an unoccupied car parked near the National Mall. They deemed it "suspicious," and took a look inside, where they found a pressure cooker. They also claimed to smell gasoline. The officers called the bomb squad, and at 7:45pm they initiated a controlled detonation of the car's contents. Afterward, a search of the car found no evidence that it contained explosives or any other hazardous materials. The car's owner was located and arrested for driving on a revoked license.

Read more of this story at Slashdot.

Categories: Science

Location matters in the lowland Amazon

Science Daily - Mon, 25/05/2015 - 4:04pm
You know the old saying: Location, location, location? It turns out that it applies to the Amazon rainforest, too. New work illustrates a hidden tapestry of chemical variation across the lowland Peruvian Amazon, with plants in different areas producing an array of chemicals that changes across the region's topography.
Categories: Science