China Science & Technology Forum

[JSCh]

Viewpoint: Lost Photons Won’t Derail Quantum Sampling

Austin P. Lund, Centre for Quantum Computation and Communications Technology, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
June 6, 2018• Physics 11, 57
​

A photon-based method for demonstrating the advantage of quantum over classical machines can handle photon loss, facilitating experiments.

A race is on to build a quantum computer that solves difficult problems much faster than a classical computer—a milestone dubbed quantum supremacy [1]. Runners in this race, however, are faced with a hazy finish line, which can move closer as quantum machines and algorithms improve or further away as their classical counterparts catch up. An experiment led by Jian-Wei Pan of the University of Science and Technology in China [2] nudges the racers forward for now. Inspired by a theoretical proposal, the researchers confirmed that a promising method for demonstrating quantum supremacy, known as boson sampling with photons (Fig. 1), produces useful output even as photons leak from the system. This means that researchers don’t have to “toss away” the output of a sampling experiment when photons are lost, as was previously assumed [3], allowing for faster computations and bringing a demonstration of quantum supremacy closer to reality.

When will we have a useful quantum computer? To make the answer concrete, consider the most famous quantum-computing algorithm—factoring large prime numbers [4]. This task will likely require millions, and possibly billions, of quantum bits (qubits) and an even larger number of the devices, or “gates,” that manipulate the qubits. Since today’s most advanced quantum computers have around 50 qubits, a quantum computer that could quickly factor large numbers is probably a long way off.


--> Physics - Viewpoint: Lost Photons Won’t Derail Quantum Sampling

Toward Scalable Boson Sampling with Photon Loss
Hui Wang, Wei Li, Xiao Jiang, Y.-M. He, Y.-H. Li, X. Ding, M.-C. Chen, J. Qin, C.-Z. Peng, C. Schneider, M. Kamp, W.-J. Zhang, H. Li, L.-X. You, Z. Wang, J. P. Dowling, S. Höfling, Chao-Yang Lu, and Jian-Wei Pan
Phys. Rev. Lett. 120, 230502 (2018)
Published June 6, 2018​

 

[JSCh]

PUBLIC RELEASE: 6-JUN-2018
Single molecular insulator pushes boundaries of current state of the art
Breakthrough could pave the way for smaller transistors

COLUMBIA UNIVERSITY SCHOOL OF ENGINEERING AND APPLIED SCIENCE

​

An illustration of the silicon-based single-molecule device that functions as an efficient insulator through a sigma-based quantum interference effect. CREDIT: Haixing Li/Columbia Engineering

New York, NY--June 6, 2018--Ever shrinking transistors are the key to faster and more efficient computer processing. Since the 1970s, advancements in electronics have largely been driven by the steady pace with which these tiny components have grown simultaneously smaller and more powerful--right down to their current dimensions on the nanometer scale. But recent years have seen this progress plateau, as researchers grapple with whether transistors may have finally hit their size limit. High among the list of hurdles standing in the way of further miniaturization: problems caused by "leakage current."

Leakage current results when the gap between two metal electrodes narrows to the point that electrons are no longer contained by their barriers, a phenomenon known as quantum mechanical tunnelling. As the gap continues to decrease, this tunnelling conduction increases at an exponentially higher rate, rendering further miniaturization extremely challenging. Scientific consensus has long held that vacuum barriers represent the most effective means to curtail tunnelling, making them the best overall option for insulating transistors. However, even vacuum barriers can allow for some leakage due to quantum tunnelling.

In a highly interdisciplinary collaboration, researchers across Columbia Engineering, Columbia University Department of Chemistry, Shanghai Normal University, and the University of Copenhagen have upended conventional wisdom, synthesizing the first molecule capable of insulating at the nanometer scale more effectively than a vacuum barrier. Their findings are published online today in Nature.

"We've reached the point where it's critical for researchers to develop creative solutions for redesigning insulators. Our molecular strategy represents a new design principle for classic devices, with the potential to support continued miniaturization in the near term," said Columbia Engineering physicist and co-author Latha Venkataraman, who heads the lab where researcher Haixing Li conducted the project's experimental work. Molecular synthesis was carried out in the Colin Nuckolls Lab at Columbia's Department of Chemistry, in partnership with Shengxiong Xiao at Shanghai Normal University.

The team's insight was to exploit the wave nature of electrons. By designing an extremely rigid silicon-based molecule under 1 nm in length that exhibited comprehensive destructive interference signatures, they devised a novel technique for blocking tunnelling conduction at the nanoscale.

"This quantum interference-based approach sets a new standard for short insulating molecules," said lead author Marc Garner, a chemist in the University of Copenhagen's Solomon Lab, which handled the theoretical work. "Theoretically, interference can lead to complete cancellation of tunneling probability, and we've shown that the insulating component in our molecule is less conducting than a vacuum gap of same dimensions. At the same time, our work also improves on recent research into carbon-based systems, which were thought to be the best molecular insulators until now."

Destructive quantum interference occurs when the peaks and valleys of two waves are placed exactly out of phase, annulling oscillation. Electronic waves can be thought of as analogous to sound waves--flowing through barriers just as sound waves "leak" through walls. The unique properties exhibited by the team's synthetic molecule mitigated tunneling without requiring, in this analogy, a thicker wall.

Their silicon-based strategy also presents a potentially more factory-ready solution. While recent research into carbon nanotubes holds promise for industrial applications over the next decade or so, this insulator--compatible with current industry standards--could be more readily implemented.

"Congratulations to the team on this breakthrough," said Mark Ratner, a pioneer in the field of molecular electronics and professor emeritus at Northwestern University who was not involved in the study. "Using interference to create an insulator has been ignored up to this date. This paper demonstrates the ability of interference, in a silicon-based sigma system, which is quite impressive."

This breakthrough grew out of the team's larger project on silicon-based molecule electronics, begun in 2010. The group arrived at their latest discovery by bucking the trend. Most research in this field aims to create highly conducting molecules, as low conductance is rarely considered a desirable property in electronics. Yet insulating components may actually prove to be of greater value to future optimization of transistors, due to the inherent energy inefficiencies caused by leakage currents in smaller devices.

As a result, their work has yielded new understanding of the fundamental underlying mechanisms of conduction and insulation in molecular scale devices. The researchers will build on this insight by next clarifying the details of structure-function relationships in silicon-based molecular components.

"This work has been extremely gratifying for us, because in the course of it we have repeatedly discovered new phenomena," said Venkataraman. "We have previously shown that silicon molecular wires can function as switches, and now we've demonstrated that by altering their structure, we can create insulators. There is a lot to be learned in this area that will help shape the future of nanoscale electronics."



Single molecular insulator pushes boundaries of current state of the art | EurekAlert! Science News

Marc H. Garner, Haixing Li, Yan Chen, Timothy A. Su, Zhichun Shangguan, Daniel W. Paley, Taifeng Liu, Fay Ng, Hexing Li, Shengxiong Xiao, Colin Nuckolls, Latha Venkataraman & Gemma C. Solomon. Comprehensive suppression of single-molecule conductance using destructive σ-interference. Nature (2018). DOI: 10.1038/s41586-018-0197-9.​

 

[JSCh]

2018 Annual Tables: Tsinghua joins elite group of research universities
Two Beijing-based universities are among the top 10 academic institutions in the Nature Index.

7 June 2018
Smriti Mallapaty

• 2018 annual tables: Academic institutions

Tsinghua University rises to 10th place among the world’s leading academic institutions for high-quality scientific research in the Nature Index 2018 annual tables.

The university has seen steady growth in its contribution to the articles tracked by the index, measured by fractional count (FC). Tsinghua has ascended from 20th rank three years ago, when it had an FC of 289. It has earned its top 10 debut with an FC of 353 in the current tables, taking a place in the higher echelons along with Peking University, whose FC of 384 sees it hold the number eight spot.

The 2018 annual tables assess institutions on their contribution to articles in scientific journals in which researchers would most want to publish their best work. This year, for the first time since its launch in 2014, the Nature Index has revised its original list of 68 high-quality journals to 82. The new list increases the coverage of articles in Earth and environmental sciences, life sciences and chemistry, to balance earlier over-representation of astronomy and astrophysics articles in the physical sciences.

Beijing-based Tsinghua and Peking are the first Chinese institutions to make it into the global academic top 10, but others are in hot pursuit. Nanjing Universityhas climbed from 21 to 13, and the University of Science and Technology of China has made its way to 18, from 27.

Chinese institutions are especially prominent in the areas of chemistry and physical sciences, though Nanjing also stands out as the only Chinese university among the top 10 in Earth and environmental sciences.

Tsinghua’s rise is largely driven by its chemistry contributions. Among notable work, researchers at the Department of Chemistry recently created a substance that warms up when exposed to light with potential use as an antidote to antibiotic-resistant bacteria.

Among the leading 100 academic institutions in the 2018 annual tables are 44 from the United States and 16 from China. The United Kingdom and Japan contribute seven each, with six from Germany, four from Switzerland and three from Canada.

Overall, almost 90% of the 83 academic institutions from China in the top 500 have improved their positions in the last year, compared to just about 45% of the 135 from the United States.

“The global picture is changing. Chinese institutions are really gaining their place,” says Marijk van der Wende, a professor of higher education and dean of graduate studies at Utrecht University in the Netherlands. “Institutions that are going up quickly take the STEM road,” she says, with many specialising in a narrow set of subjects.

Tsinghua University is the top producer of articles in the top 10% of highly-cited research in mathematics and computer science, as well as in physical sciences and engineering, according to the CWTS Leiden Ranking 2018. Its mathematics and computer science papers in the top 10% of highly-cited articles increased from 164 in 2006–2009 to 432 in 2013–2016. In physical sciences and engineering, its papers published in this category more than doubled over the same period.

Chinese institutions also lead in several fields tracked by the 2017 Academic Ranking of World Universities. They rank first in instruments science & technology, metallurgical engineering, mining, telecom engineering, civil engineering and remote sensing. “The government’s investments and policies are apparently taking effect,” says van der Wende.

In Nature Index’s closed circuit, with institutions vying for a finite share of articles in the leading journals, as some institutions rise, others must fall. Yale University dropped from 10th place to 19 in the past year, with an FC in the current tables of 298. Some of the decline can be attributed to a growing emphasis on collaboration. As researchers at Yale and other universities increasingly look beyond their campuses for co-authors, their share of total paper authorship in the index database might decline slightly.

Other institutions in the top 10 whose FC has declined in the past year include Massachusetts Institute of Technology in the US, and the University of Cambridge and University of Oxford in the UK.

Those whose FC has increased in the past year include Harvard University, Stanford University, and the University of California Berkeley in the US, The University of Tokyo in Japan, and the Swiss Federal Institute of Technology Zurich in Switzerland.

Harvard University, with an FC more than double that of Tsinghua, rests comfortably at the top for the third year running.

Data analysis by Aaron Ballagh and Bo Wu.


2018 Annual Tables: Tsinghua joins elite group of research universities | Nature Index

 

[JSCh]

Family Genetics Study Reveals Possible New Drug Target to Lower Blood Cholesterol
Jun 07, 2018
staff reporter

NEW YORK (GenomeWeb) – Researchers in China have discovered a protein that regulates the uptake of dietary cholesterol in the gut, and which might serve as a drug target to keep blood cholesterol levels in check and prevent heart disease.

A truncated version of the protein, called LIMA1, has led to unusually low levels of low-density lipoprotein cholesterol (LDL-C) and reduced cholesterol absorption in a family of Chinese Kazahks, the researchers found, and additional experiments in mice further explored the molecular role of LIMA1.

The team, led by scientists at Wuhan University and Xinjian Medical University, published its findings in Science today.

High levels of LDL-C in the blood are a known risk factor for cardiovascular disease. Up to 50 percent of variance in LDL-C concentration are thought to be genetic, but known genetic factors only explain a fraction of the observed variation. To find new LDL-C-associated genetic variants, the researchers homed in on Chinese Kazakhs, an isolated ethnic group in western China that differs genetically from other populations and in whom lipid genetics studies had not been conducted yet.

Specifically, they focused on a Chinese Kazakh family with inherited low levels of LDL-C, sequencing the exomes of three family members with low LDL-C and one with normal LDL-C. This led them to seven candidate variants, of which only one — a truncating frameshift deletion in the LIMA1 gene (also known as EPLIN and SREBP3) — cosegregated with the low LDL-C phenotype in the family.

In general, LDL-C levels are influenced by both the body's own cholesterol synthesis and by the uptake of dietary cholesterol in the intestine. Mass spec-based analysis of cholesterol-related compounds in family members with the LIMA1 mutation showed that their intestinal cholesterol absorption was impaired, suggesting a role for LIMA1 in that process.

Targeted sequencing of LIMA1 in 509 additional Chinese Kazakh individuals with low LDL-C levels found that one carried the same mutation as the family, whereas none of 510 Chinese Kazakhs with normal LDL-C levels did. The researchers also discovered three additional families, all with low LDL-C levels, who had a different LIMA1 mutation that appears to destabilize the protein.

To further investigate the function of LIMA1 in cholesterol metabolism, they conducted a number of studies in mice. The protein appears to be most highly expressed in the small intestine, especially in the brush border membrane, and mice lacking LIMA1 in their intestines showed lower cholesterol uptake than wild-type mice.

Further studies revealed that LIMA1 probably acts as a scaffold protein that forms a triplex complex with NPC1L1, a transmembrane protein that facilitates the uptake of cholesterol through vesicles, and myosin Vb.

Ultimately, the scientists concluded, LIMA1 might serve as a new drug target to lower LDL-C in patients. "A growing body of evidence has indicated that lower LDL-C levels are associated with reduced risk of [cardiovascular disease]," they wrote, adding that although LDL-C can already be decreased by statins and other drugs, "inhibition of LIMA may provide a new direction for treating hypercholesterolemia."



Family Genetics Study Reveals Possible New Drug Target to Lower Blood Cholesterol | GenomeWeb

Ying-Yu Zhang, Zhen-Yan Fu, Jian Wei, Wei Qi, Gulinaer Baituola, Jie Luo, Ya-Jie Meng, Shu-Yuan Guo, Huiyong Yin, Shi-You Jiang, Yun-Feng Li, Hong-Hua Miao, Yong Liu, Yan Wang, Bo-Liang Li, Yi-Tong Ma & Bao-Liang Song. A LIMA1 variant promotes low plasma LDL cholesterol and decreases intestinal cholesterol absorption. Science (2018). DOI: 10.1126/science.aao6575​

 

[JSCh]

Chinese scientists improve fetal imaging equipment
Source: Xinhua| 2018-06-09 20:16:03|Editor: Yamei


BEIJING, June 9 (Xinhua) -- Chinese scientists have improved key components in Magnetic Resonance Imaging (MRI) equipment, creating clearer fetal imaging.

MRI is an important tool for discovering complex congenital diseases during fetal development. It is especially useful in the diagnosis of neurodevelopmental abnormalities and cardiovascular diseases.

Coils are a key component of MRI equipment. Due to a lack of coils that can fit the body sizes of the pregnant, standard abdominal coils are often used for fetal imaging. However, their performance is limited by insufficient coverage.

Scientists from Shenzhen Institutes of Advanced Technology have developed a dedicated coil specifically for fetal imaging. It can increase imaging speed and achieve clearer imaging of fetal development.

The research was published in IEEE Transactions on Medical Imaging.

The technology is being adopted by a Chinese medical imaging equipment company and is expected to be ready for clinical application by the end of the year.

 

[JSCh]

China finds greener way to make lithium batteries
Source: Xinhua| 2018-06-10 22:20:02|Editor: Li Xia


NANCHANG, June 10 (Xinhua) -- A new method for extracting lithium in a greener and more efficient way has passed China's state-level appraisal, paving way for its commercialization to boost the new energy sector.

Qiu Zumin, professor of the institute of environmental science and engineering in Nanchang University, said the new lithium extraction technology has passed the national scientific and technological achievements appraisal. It is expected to replace current lithium extraction methods in China, which have been blamed for producing huge amounts of waste, and have low profitability.

Lithium batteries are essential to power modern electronic devices, such as mobile phones, laptops and electronic cars. Lithium is also used in medicine, pottery, glass and other industries.

Lithium cells rely on lithium carbonate as the raw material. China imports 80 percent of its lithium carbonate, though it is rich in lithium resources, due to backward mining technology.

With traditional methods, 30-40 tonnes of waste are produced in making 1 tonne of lithium carbonate. It is also very costly to treat the waste.

The new method is jointly developed by the Jiangxi Haohai Lithium Energy, Nanchang University and other institutions. It can separate all the elements in lithium micas.

Peng Guiyong, chair of Haohai, said the company plans to invest 1 billion yuan (156 million U.S. dollars) to build a production line with an annual capacity of 40,000 tonnes of lithium carbonate.

Jiangxi boasts the world's largest lithium mica mine. The province's reserve of lithium oxide accounts for one-third of China's total.

 

[JSCh]

CMS Collaboration Reports Observation of Higgs Particle Interaction with Top Quark
Jun 08, 2018

The Compact Muon Solenoid (CMS) collaboration at the Large Hadron Collider published the first observation of ttH production in Physical Review Letters (PRL) on June 4th, 2018. This observation gives direct proof that the Higgs particle couples to the top quark, which is a key element in understanding the origin of fermion mass.

After the discovery of the Higgs boson at the ATLAS and CMS experiments in 2012, two new interactions were predicted: the Yukawa coupling between the Higgs and fermions, and the Higgs self-interaction. However, there were no direct observations in any experiments of these two interactions, until this first report of a direct observation of the Higgs interacting with one of the fermions: the top quark. This observation of ttH indicates the coupling between the Higgs and fermions does exist.

The CMS group from the Institute of High Energy Physics (IHEP) of Chinese Academy of Sciences was involved in the effort to hunt for ttH production, and made a significant contribution to ttH observation in the most sensitive Higgs decay channels, the WW, bb, di-photon and ZZ channels.

To extract ttH signal from overwhelming backgrounds, they developed a dedicated method to tag jets from higgs boson decays, and introduced new variables to distinguish whether a lepton is isolated from jets or not. These methods were two of the key elements in the success of the ttHWW analysis. This analysis makes ttHWW turned out to be the most important channel contributing to the observation of ttH.

The CMS group gave the pre-approval talk within the CMS collaboration on behalf of the ttHWW analysis team. They also made a significant contribution to ttHbb analysis by introducing the b-jetness method.

However, the observed production rate of ttH is slightly higher than the prediction from the Standard Model of particle physics, within two sigma of uncertainty, leaving room for new physics. Only data taken up to 2016 was used in this observation, and further analysis with more data in future is expected to probe the details of the Higgs-top quark Yukawa coupling through ttH production.

For more information please see:

CMS press release: http://cms.cern/news/tth-announcement

CERN Courier: http://cerncourier.com/cws/article/cern/71524

CERN press release: https://press.cern/press-releases/2018/06/higgs-boson-reveals-its-affinity-top-quark

APS Viewpoint: https://physics.aps.org/articles/v11/56

Best fit value of the ttH signal strength modifier u_ttH compared to SM expectation (Image by CMS Collaboration)
​

CMS Collaboration Reports Observation of Higgs Particle Interaction with Top Quark---Chinese Academy of Sciences

 

[JSCh]

Day–night temperature fluctuations power hydrogen evolution
BY ALICE STEVENSON
11 JUNE 2018

Pyrocatalytic nanoparticles split water and produce hydrogen

Scientists in China and Hong Kong have split water at room temperature using a special type of functional material that can generate an electric charge from the natural change in temperature from day to night. The team used nanoparticles that can convert thermal energy into an electric charge big enough to catalytically split water molecules into hydrogen gas.

‘Hydrogen fuel cells are a promising alternative energy conversion technology due to zero greenhouse gas emissions and a high energy output’, explains Hamideh Kanbareh, an expert in functional materials from the University of Bath, UK, who was not involved in this study. Using solar energy to split water into hydrogen and oxygen is an attractive way to generate hydrogen fuel. However, the process suffers from low efficiencies and doesn’t work in the dark, which limits this idea in practice. The largely unexplored area of thermal energy harvesting for hydrogen production could solve these problems.

Source: © Royal Society of Chemistry
Scientists have used the pyroelectric nanomaterial Ba0.7Sr0.3TiO3 to generate hydrogen using cold–hot temperature fluctuations

Now, a team led by Yanmin Jia, of Zhejiang Normal University, and Haitao Huang, of Hong Kong Polytechnic University, have used pyroelectric materials to split water at room temperature. ‘Pyroelectric materials are a type of material that can generate electric charges on two oppositely polarised surfaces under a temperature change,’ explains Jia. ‘Unlike conventional water electrolysis, our technique does not require electric energy. It makes use of the daily temperature variations to produce useful hydrogen’.

The team’s pyroelectric material was made from barium strontium titanate nanoparticles. Jia and Huang noticed that the pyroelectric voltage produced by the material after a temperature change could be as large as several volts so was sufficient for electrolysing water. Jia explains that they used nanoparticles as ‘in theory, nanomaterials with small size and high surface area can speed up electric charge migration between water and the pyroelectric materials, which may increase the efficiency of hydrogen evolution’.

‘This study demonstrates a novel, efficient and eco-friendly material system, which can generate hydrogen,’ comments Hamideh. ‘I find alternative routes for energy scavenging very interesting. Their next step would be to extend the material’s performance to simultaneous oxygen production as well as hydrogen’.

References
This article is free to access until 23 July 2018
X Xu et al, Energy Environ. Sci., 2018, DOI: 10.1039/c8ee01016a​

Day–night temperature fluctuations power hydrogen evolution | Research | Chemistry World

 

[JSCh]

EDITORIAL 12 JUNE 2018
China sets a strong example on how to address scientific fraud
New measures introduce what could be the world’s strongest disincentive for misconduct so far.

China has announced tough new rules to beat research fraud.Credit: Anthony Kwan/Bloomberg/Getty​

The Chinese government knows that a slice of its generous science budget — the world’s second-largest by country — goes to waste on bad science. It doesn’t want to waste any more. On 30 May, the State Council and the Communist Party of China announced a radical new system of regulations to police science and raise research standards in the country.

Certainly, reform is necessary and overdue. Various Chinese government bodies have made the case to crack down on fraud and misconduct in science over the past two decades, but with limited success. This time, the changes have serious political weight behind them and could make a significant difference. The policy might offer the greatest disincentive to cheating in research that the world has seen so far. But the devil, as always, will be in the detail — and in how well the plans are enforced.

One of the most striking conditions is that researchers will be deterred from publishing findings in journals that China deems to be of poor academic quality, poorly managed and set up merely for profit. Many such ‘predatory journals’ offer researchers a place to publish, for a fee, and shirk their editorial responsibility to evaluate papers to determine quality. China’s science ministry is working on a blacklist of those journals. In an unprecedented step, any researcher who publishes in one will get a warning and be given no credit for the publication when they are evaluated for grants or jobs. Using government grants to pay the publication fees in these journals, as many presumably do, could land Chinese scientists in deeper trouble.

As the world’s largest producer of scientific papers, China’s new rules could go as far as to put some of these rogue journals out of business, and that could be good for scientists everywhere. (Although, as we discussed in a News story last week, some scientists are anxious about how these journals are identified, while others have concerns about such blacklists and prefer ‘whitelists’ of approved publications.)

In another major shift, China is handing the responsibility for deterring and investigating scientific misconduct to the government’s science ministry. That’s quite a shake-up for China, where — as in many places — institutions are usually expected to investigate allegations against their own researchers. That is too often ineffective. With little to gain and a reputation to lose, many prefer to sit on their hands and wait for the situation to blow over.

Denmark, for instance, has designated a national agency to police science, but, too frequently, there is limited will and scant resources to pursue allegations of fraud at the government level. In the United States, for example, the Office of Research Integrity is short-staffed and has limited leverage over universities.

In China, the situation could play out differently. The new rules state explicitly that institutions that shield errant scientists can be punished through a loss of funding. That could give the policy real teeth — enough to drastically clean up Chinese research. But success will take sustained effort and pressure from the top, and because there is no guarantee of that, the policy could equally fall flat. China’s bureaucrats are not responsive to its citizens — no matter how loud the cry on social media for an investigation into a given scientist — and they make almost no effort to be transparent. The science ministry could stick its head in the sand just as deeply as some institutions do.

There are other causes for concern. The science ministry is also drawing up rules on how penalties will be meted out — including the blacklisting of scientists who have committed particularly egregious acts. To maintain fairness, harsh penalties require assurances that the judgements leading to them are based on thorough and fair evaluations.

China’s bureaucrats might not answer to the people, but they do answer to the higher echelons of power. The current push for better management of science comes as part of President Xi Jinping’s wider anti-corruption drive. Xi regularly talks up the crucial role of science and technology in making China stronger and more independent. With its new rules, China is backing words with actions.

Nature 558, 162 (2018)

doi: 10.1038/d41586-018-05417-1


China sets a strong example on how to address scientific fraud | Nature

 

[JSCh]

Nanotechnology limits pushed
By ZHANG ZHIHAO | China Daily | Updated: 2018-06-14 07:36

China has made several breakthroughs in cutting-edge nanotechnology in the past five years that will have significant applications in electric vehicles, industrial printing and public health, scientists said on Wednesday.

Nanoscience is the study of materials on the scale of nanometers－a unit of measurement that is a billionth of a meter. At such a tiny scale, the properties of materials are often drastically different from those at larger sizes.

Materials that are brittle can become incredibly strong, and compounds that are chemically inert can become powerful catalysts. Manipulating these novel properties will lead to a wide range of products, from batteries to water filtration systems.

In recent years, China has created a lithium-ion power battery capable of safely storing 300 watt hours per kilogram of mass, which could power a more than 500 kilometer trips in the EV 200 electric sedan produced by Beijing Automotive Group Co, said Wang Chen, a researcher from the National Center for Nanoscience and Technology.

This battery's energy density is on par with the latest battery used in Tesla's new Model 3 sedan, which has one of the cheapest and highest energy density cells on the market, according to Tesla and Panasonic, the battery's manufacturer.

Chinese scientists are now optimizing the new battery in preparation for vehicle demos, said Wang, adding that the Chinese Academy of Sciences has partnered with more than 30 battery and electric vehicle companies to introduce the new battery into the market.

At the same time, China has used nanotechnologies to make breakthroughs in the next generation of rechargeable batteries, namely lithium-sulfur and lithium-air batteries, said Li Hong, a researcher at the Chinese Academy of Sciences' Institute of Physics.

"For decades, the United States and Japan have held key patents and technologies on lithium-ion batteries," said Li. "But China can keep up with them or even take the lead in fields related to the next generation of rechargeable batteries."

Compared with lithium-ion batteries, lithium-sulfur batteries use sulfur rather than expensive alloys for electrodes, making them cheaper, lighter and able to store almost double the energy for the same mass. China has created a world-leading lithium-sulfur battery capable of holding 609 Wh/kg, Li said.

The lithium-sulfur battery has been successfully tested in commercial solar powered drones, he added. China has also formed its first lithium-sulfur battery production company, Zhongke Paisi Energy Storage Technology Co, located in Dalian, Liaoning province, and it has recently finished building the world's largest production line for the new battery.

The lithium-air battery takes innovation further by using oxygen from the air for electrodes. It has all the benefits of lithium-sulfur batteries plus being even more environmentally friendly. Chinese scientists have produced a lithium-air battery that can store 780 Wh/kg, Li said.

Although the technology is relatively new and still needs more testing, "it will significantly increase China's technological and engineering prowess in the global race for smaller, longer-lasting, more powerful batteries," Li said.

New nanomaterials also helped China develop a new printing method that is both cost-efficient and does not produce corrosive or poisonous waste, said Song Yanlin, a researcher from the Institute of Chemistry from the academy.

The new technology will help transform China's industrial printing industries, whose turnover was $180 billion in 2016, to be completely environmentally friendly, he said. It will also reduce the harmful chemicals used to etch prints on electronics.

Nanomaterials can also be used to create portable water filtration systems for more than 1,200 nomadic families in North China's Inner Mongolia autonomous region, said Fang Shibi, a researcher at the Institute of Chemistry.

The new nanomaterial used in the water filters can effectively purify the arsenic and fluorine, and the nomads need only change the filters once per year, making clean water cheap and more accessible, he added.

 

[JSCh]

PUBLIC RELEASE: 13-JUN-2018
E- textiles control home appliances with the swipe of a finger (video)
AMERICAN CHEMICAL SOCIETY

A newly developed e-wristband is self-powered, highly sensitive and washable. CREDIT: American Chemical Society​

Electronic textiles could allow a person to control household appliances or computers from a distance simply by touching a wristband or other item of clothing -- something that could be particularly helpful for those with limited mobility. Now researchers, reporting in ACS Nano, have developed a new type of e-textile that is self-powered, highly sensitive and washable. A video of an e-wristband in action is available here.

E-textiles are not new, but most existing versions have poor air permeability, can't be laundered or are too costly or complex to mass-produce. Jiaona Wang, Hengyu Guo, Congju Li and coworkers wanted to develop an E-textile that overcomes all of these limitations and is highly sensitive to human touch.

The researchers made a self-powered triboelectric nanogenerator by depositing an electrode array of conductive carbon nanotubes on nylon fabric. To make the E-textile washable, they incorporated polyurethane into the carbon nanotube ink, which made the nanotubes firmly adhere to the fabric. They covered the array with a piece of silk and fashioned the textile into a wristband. When swiped with a finger in different patterns, the E-textile generated electrical signals that were coupled to computers to control programs, or to household objects to turn on lights, a fan or a microwave from across the room. The E-textile is breathable for human skin, washable and inexpensive to produce on a large scale, the researchers say.



E- textiles control home appliances with the swipe of a finger (video) | EurekAlert! Science News

Ran Cao, Xianjie Pu, Xinyu Du, Wei Yang, Jiaona Wang, Hengyu Guo, Shuyu Zhao, Zuqing Yuan, Chi Zhang, Congju Li, Zhong Lin Wang. Screen-Printed Washable Electronic Textiles as Self-Powered Touch/Gesture Tribo-Sensors for Intelligent Human–Machine Interaction. ACS Nano, 2018; DOI: 10.1021/acsnano.8b02477​

 

[JSCh]

2018.06.13
PolyU develops novel Micro-embossing Equipment for Precision Optical Microstructures

The Hong Kong Polytechnic University (PolyU) has developed a novel micro-embossing equipment for manufacturing precision glass lenses with high image quality and resolution required for state-of-the-art optical instruments and devices in varied fields – from astronomy, national defence, medical scanning, to consumer products such as cameras and mobile phones. The invention can emboss ultra-precise optical microstructures in glass in a much environmentally friendly way than conventional machines, saving electric power by 60 times and reducing manufacturing cost by two-thirds.

Developed by PolyU researchers from the Partner State Key Laboratory of Ultraprecision Machining Technology, the invention was awarded a Gold Medal at the 46th International Exhibition of Inventions of Geneva 2018. The research supported by the Innovation Technology Fund has also been granted with eight patents.

Glass optical components are difficult to fabricate as it requires much higher molding temperature and extremely hard-to-machine carbide materials to make the mold, compared with plastic molding. It is also difficult to emboss micro-nano optical elements with micron-sized glass microstructures (1 micron = 1 of 1 million parts of a metre). However, with surging demand for powerful lens of small size and high resolution in advanced optical systems nowadays, there has been mounting need for using optical glass to replace optical polymers, which has much lower transmittance. Taking DVD high-definition optical pickup lens as an example, the feature size is as tiny as 0.9 micron. If conventional lithography method is used for mass production, the equipment set up cost will be high, yet the lens produced will have precision much lower than those obtained from molding or embossing. Nowadays, China has the highest output of optical lenses in the world. Yet, due to technological limitation for producing high-end lens, its total market value is still lower than Europe and Japan.

The research team led by Professor LEE Wing Bun and Dr LI Lihua from PolyU's Department of Industrial and Systems Engineering has adopted a novel molding design with graphene-like coating and self-developed heating technology to produce the micro embossing equipment that can produce micron-level microstructural optical components in glass. Compared to conventional bulky infrared heating device with large energy consumption, the novel technology is much environmentally friendly and cost effective.

The use of graphene-like coating can heat up the optical glass precisely and quickly with low energy consumption, while reducing thermal expansion and deformation of the mold. The control and monitoring software developed can also provide online and instant readings of the temperature, which allow fine-tuning and adjustment of the process parameters, and thus shorten the cycle time. Such novel features enable saving electric power by up to 60 times, compared to conventional infrared machines, and cutting the manufacturing cost by two-thirds. Being an electrical conductive material with high wear characteristic, graphene also enables smooth stripping of the glass workpiece from the mold after the embossing process. Furthermore, micro-pattern with micron accuracy can be replicated on the glass substrate.

The novel embossing equipment can have wide applications in opto-electronic products, including cell phone micro-lenses, camera lenses, DVD pickup lenses, micro shuttle lenses, f-theta lenses for laser printers, projection television magnifiers, optical communication V Gutter substrate, micro-lens array (MLA), and Frensel lens for collecting and tracking solar energy. In light field optics, the new applications of great potential include 3D camera heads, three-dimensional robotic vision systems, as well as lens for long-range shooting, detection of low-altitude drones and security monitoring.


PolyU develops novel Micro-embossing Equipment for Precision Optical Microstructures - PolyU

 

[JSCh]

Chinese scientists identify new mammal ancestor
Source: Xinhua| 2018-06-14 14:10:25|Editor: ZD


KUNMING, June 14 (Xinhua) -- Chinese palaeobiologists have identified a new mammal ancestor and indicating that marsupials may not have originated in Asia.

Well-preserved skeletons of Ambolestes zhoui from 126 million years ago were found in Yixian County in north China's Inner Mongolia Autonomous Region, said Professor Bi Shundong of Yunnan University palaeobiology lab, who led the research.

Over the past 20 years, fossils of 120 vertebrate species, generally known as the Jehol biota, have been found in the Mesozoic site.

The skeletons show details unknown in contemporaneous mammals after researchers used CT and 3D technology to reconstruct the structure of every bones, said Bi.

"Ambolestes zhoui is an early member of the placental lineage. It also carries mixed features both placentals and marsupials," he said.

"Our conclusion means that Asia may not be the place of origin for marsupials," he said. The oldest known marsupials are from 110 million years ago from west North America.

On the basis of the research, researchers have also established a database on the lineage of early mammals.

The research findings are published in the Nature science journal.

 

[JSCh]

11 JUNE 2018 • https://doi.org/10.1063/1.5043415
New tandem upconversion device improves night vision technology
Mara Johnson-Groh

An improvement on conventional organic upconversion devices demonstrates improved efficiency for converting near-infrared light to visible, and may be a promising future for low-cost, large-area imaging technology.

Researchers have developed a better way of seeing in the dark. In Applied Physics Letters, the research team reports improving on near-infrared upconversion devices, which convert near-infrared radiation to shorter, visible wavelengths. They created a two-stage, tandem device using organic light-emitting diodes (OLEDs). With much higher efficiencies than previous models, the device may offer a promising alternative for low-cost, large-area imaging technologies.

--> New tandem upconversion device improves night vision technology: Scilight: Vol 2018, No 24

Source: “Integrated tandem device with photoactive layer for near-infrared to visible upconversion imaging,” by Shou-Jie He, Deng-Ke Wang, Zhen-Xin Yang, Jia-Xiu Man, and Zheng-Hong Lu, Applied Physics Letters (2018). The article can be accessed at https://doi.org/10.1063/1.5023430.​

 

[JSCh]

Printed metal-polymer conductors make stretchy biodevices
18 Jun 2018 Belle Dumé

Stretchy biodevice​

Stretchable biocompatible devices can be used in a host of medical applications, but most stretchable conductors made to date are toxic, expensive, difficult to make and break or degrade easily. A team of researchers at the National Center for Nanoscience and Technology in Beijing, China, has now printed the first flexible metal-polymer electronic circuits that are at once highly conductive and stretchable, biocompatible, non-toxic and easy and cheap to make. The circuits, which are made of eutectic gallium indium particles embedded in a polymer matrix, can take most 2D shapes and could find use in motion sensors, wearable glove keyboards, soft robotics and implantable devices to name but a few applications.

Eutectic gallium indium (EGaIn) is a liquid metal and can thus withstand large deformations. The material also boasts a high conductivity and is much less toxic than other metals that are also liquid at room temperature, such as mercury. Since it cannot be directly patterned using conventional techniques like stencil or ink-jet printing (its surface tension is too high), the researchers, led by Xingyu Jiang, embedded particles of the liquid metal onto the surface of a polymer (PMDS) instead. They did this by casting and peeling off steps rather than using a marker or nozzle.

The result is a printed conductive material with a good stretchability of 2.316 S/cm at a strain of 500% over more than 10 000 cycles of repeated stretching. Another advantage of the technique employed to make it is that the liquid metal particles remain on the surface of the substrate (rather than being buried deep inside), which means that functional electronic components can easily be mounted on top of them.

Many applications
The researchers used the printed metal-polymer conductors in a variety of applications, including in sensors for wearable keyboard gloves, motion sensors and in electrodes for electroporation (stimulating the passage of DNA through the membranes of live cells).

“The applications of the metal-polymer conductors depend on the polymer employed,” says study first author Lixue Tang. “We cast super-elastic polymers to make metal-polymer conductors for stretchable circuits or biocompatible and biodegradable polymers when we want to make implantable devices. In the future, we could even build soft robots by combining electroactive polymers.”

The technique can be used to make printed materials that can conform to any 2D shape, say the researchers. And they can be made in different thicknesses with varying electrical properties depending on the concentration of the liquid metal inks employed. This means that they could be used in a host of biomedical applications, including flexible patches that could even be wrapped around the heart to monitor and treat cardiac disease.

Indeed, the researchers say that they are now planning to fabricate a biodegradable cardiac patch patterned by their metal-polymer conductor electrodes to enhance the conductivity of myocardial cells and monitor electrophysiological signals. The applications are many: “Wearable electronics, implantable devices, soft robotics, future fabrics, virtual/augmented reality, flexible displays, artificial organs, brain-computer interfaces, and wherever biocompatible, soft electronics is necessary,” says Tang.

The research is detailed in iScience 10.1016/j.isci.2018.05.013.


Printed metal-polymer conductors make stretchy biodevices – Physics World