China Science & Technology Forum

[JSCh]

An expanse of soil and rock measuring 2.4 kilometres long and 1.2 kilometres wide tumbled down Daguangbao mountain in China after a massive earthquake. Credit: W. Hu et al./Earth Planet. Sci. Lett.

GEOPHYSICS * 15 FEBRUARY 2019
The vaporized rock and extreme heat at a huge landslide’s heart
An entire mountainside came crashing down after a devastating earthquake in China’s Sichuan Province.

A gargantuan landslide in China generated enough heat to vaporize some of the sliding material, creating superheated steam that helped the avalanche of rock to barrel downhill.

In 2008, the magnitude-8.2 Wenchuan earthquake shook loose more than a cubic kilometre of soil and stone from the summit and flank of Daguangbao mountain in central China. A team led by Runqiu Huang at Chengdu University of Technology in China analysed rock samples from the landslide to study conditions within the flow. By comparing rock samples with the results of friction experiments in the laboratory, the scientists concluded that temperatures at the boundary between the slide and the intact slope reached at least 850°C.

That would have partially vaporized a mineral called dolomite in the rock, releasing high-pressure, high-temperature carbon dioxide and steam that would have allowed the landslide to flow. At the same time, the immense pressure on the minerals would have caused them to recrystallize, lubricating the sliding surface and helping the debris to hurtle more than 4 kilometres from its original location.

The work offers clues to how big landslides travel long distances.

Earth Planet. Sci. Lett. (2019)
​

The vaporized rock and extreme heat at a huge landslide’s heart : Research Highlights | Nature.com

 

[JSCh]

New Technique Improves Transparent Wood
Researchers use a more environmentally friendly approach to make larger see-through wood panels than before.

Image credits: Courtesy of Rongbo Zheng

TECHNOLOGY
Friday, February 15, 2019 - 14:45

Yuen Yiu, Staff Writer

(Inside Science) -- Inspired by a technique first developed by botanists during the 1990s, materials scientists in the past few years have been making an almost oxymoronic-sounding material: transparent wood. While the biologists, who were studying the structure of wood, needed only small pieces, materials scientists have proposed applications like load-bearing windows and have focused on scaling up the technique.

Now, researchers from China have brought see-through wood one step closer to commercial application.

According to a paper published in the Journal of Materials Research this month, the authors made panels of transparent wood that are bigger, thicker, and more transparent than their predecessors, while at the same time using a manufacturing process that is more environmentally friendly.

Instead of boiling the wood in bleaching solutions to strip it of its lignin -- the stuff that makes wood opaque -- the researchers steamed the wood with hydrogen peroxide over several hours before backfilling the stripped-down wood panels with transparent resin. According to the authors, their technique can remove more lignin deeper into the wood grains, which makes the final product more transparent. They also claim that by steaming instead of boiling the wood, the wood’s cellular structure can remain relatively intact (chefs would know), which makes the final product stronger.

However, the researchers might have made their experiment easier by using wood panels that were cut across the fibers instead of along the grains, which might have made it easier for the lignin to bleed out. It would be interesting to see how the technique would fare in other cuts of wood, said Lars Berglund, a materials scientist from KTH Royal Institute of Technology in Sweden not involved in the latest research, in an article in the MRS Bulletin.

Before the material is ready for real-world applications, researchers will need to further explore its mechanical properties and the scalability of the manufacturing techniques. But when that day finally comes, we might be able to build greenhouses with tough, transparent wood panes, a sight that could confuse philosophers who say that those who live in glass houses should not throw stones.


New Technique Improves Transparent Wood | Inside Science

 

[JSCh]

Photons reveal a weird effect called the quantum pigeonhole paradox
Three quantum ‘birds’ can fit in two ‘pigeonholes’ without any two being in the same hole

BY EMILY CONOVER
6:00AM, FEBRUARY 13, 2019

STRANGE BIRDS Two pigeons can sit comfortably in two holes, but add a third bird and they’ll have to share. But three quantum particles can occupy two states without any having the same state, scientists have shown.
CHERYLRAMALHO/SHUTTERSTOCK

Quantum pigeons don’t like to share.

In keeping with a mathematical concept known as the pigeonhole principle, roosting pigeons have to cram together if there are more pigeons than spots available, with some birds sharing holes. But photons, or quantum particles of light, can violate that rule, according to an experiment reported in the Jan. 29 Proceedings of the National Academy of Sciences.

The pigeonhole principle states that, if three pigeons are roosting in two holes, one hole must contain at least two birds. Though seemingly obvious, the idea helps define the fundamentals of what numbers are and what it means to count things. But in the quantum realm, scientists had predicted that three “pigeons” — technically, quantum particles — could squeeze into two holes without any one particle sharing a hole with another, in what’s known as the quantum pigeonhole effect (SN Online: 7/18/14).

The “quantum pigeonhole effect challenges our basic understanding…. So a clear experimental verification is highly needed,” study coauthors Chao-Yang Lu and Jian-Wei Pan, physicists at the University of Science and Technology of China in Hefei, wrote in an e-mail. “The quantum pigeonhole may have potential applications to find more complex and fundamental quantum effects.”

In the study, three photons took the place of the pigeons. Rather than crowding the photons into holes, the researchers studied the polarization of the particles, or the orientation of the photons’ wiggling electromagnetic waves, which can be either horizontal or vertical. Since there were three photons and two polarizations, standard math would suggest that at least two must have had the same polarization. When the scientists compared the particles’ polarizations, the team found that no two particles matched, verifying that the quantum pigeonhole effect is real.

The mind-bending behavior is the result of a combination of already strange quantum effects. The photons begin the experiment in an odd kind of limbo called a superposition, meaning they are polarized both horizontally and vertically at the same time. When two photons’ polarizations are compared, the measurement induces ethereal links between the particles, known as quantum entanglement. These counterintuitive properties allow the particles to do unthinkable things.

While the result isn’t the first experimental confirmation of the idea, it improves on previous efforts. “I believe this paper is the best experiment done so far,” says Jeff Tollaksen of Chapman University in Orange, Calif., who was part of a team of theoretical physicists that originally proposed the effect in 2014.

The study is the first to confirm that quantum pigeons misbehave only under a specific condition. Tollaksen and his colleagues had predicted that, in order for the effect to occur, the measurement of the polarizations must be gentle, so as not to perturb the delicate quantum particles. The new work confirmed that the measurement has to be weak for the effect to occur.

Quantum mechanics is known for its odd animal-themed paradoxes — typically involving cats. Schrödinger’s cat is the star of a famous conundrum in which a feline appears to be simultaneously alive and dead (SN: 6/25/16, p. 9). And quantum “Cheshire cats” appear when particles are separated from their properties, similar to how the Alice in Wonderland cat’s grin separated from its face (SN: 9/6/14, p. 12). Like the rest of the quantum menagerie, the quantum pigeonhole effect “shows something extremely surprising, if not at first blush seemingly impossible,” Tollaksen says.

Citations
M.-C. Chen et al. Experimental demonstration of quantum pigeonhole paradox. Proceedings of the National Academy of Sciences. Vol 116, January 29, 2019, p. 1549. doi:10.1073/pnas.1815462116.​

Photons suggest the weird quantum pigeonhole paradox is real | Science News

 

[JSCh]

High-power Lasers Drive Terahertz Pulse Energy to New Record in Laboratory
Feb 18, 2019

Electromagnetic waves between infrared and microwaves are called as Terahertz (THz) radiation. It is a big challenge to generate intense THz radiation, which is significantly important for THz sciences and applications in many interdisciplinary fields.

Although THz sources have been generated with electronic and optical techniques for the last decades, the THz pulse energy reported is lower than a millijoule.

Results recently published in PNAS show that strong terahertz bursts with tens millijoules of energy, a world record for laboratory sources, can be obtained using high-power lasers.

Prof. LI Yutong's groups from Institute of Physics, Chinese Academy of Sciences, Prof. ZHANG Jie's group from Shanghai Jiaotong University, in collaboration with Prof. David Neely from Central Laser Facility, STFC Rutherford Appleton Laboratory, Prof. Paul McKenna from University of Strathclyde, and UK scientists from the University of York have studied THz radiation from intense laser-metal foil interactions.

Using the Vulcan laser at the Central Laser Facility, the record for the highest energy in a single pulse of terahertz radiation has been achieved in the laboratory.

The generation of such a strong THz source is mainly due to the coherent transition radiation when an energetic electron bunch crossing the rear surface of the thin foil. The electron bunch with high charge is accelerated by the high intensity laser pulses in the mm-sized solid metal foil.

Terahertz are already used in tech in many fields. For example, the full body scanners for airport security check. The powerful THz source driven by high power lasers provides opportunities to look at nonlinear dynamics in matter.

This study entitled "Multi-millijoule coherent terahertz bursts from picosecond laser-irradiated metal foils" was published on PNAS.

The study was supported by the National Science Foundation, the Ministry of Science and Technology of China, the Chinese Academy of Sciences, National Postdoctoral Program for Innovative Talents, Newton and Engineering and Physical Sciences Research Council of UK.

Fig.1 Comparison of currently available high-peak-power THz sources. The data are referenced from previously reported typical results of THz sources based on conventional accelerators (black squares), optical rectification from crystals (blue circles) like lithium niobate (LN) and organic crystals, and gas/solid-density plasmas (green triangles). The red star represents the data presented in this paper. Magenta curves represent different energy ranges for half-cycle THz pulses. (Image by Institute of Physics)

Related link: Record result for T-ray pulse energy obtained in a laboratory so far using Vulcan laser



High-power Lasers Drive Terahertz Pulse Energy to New Record in Laboratory---Chinese Academy of Sciences

 

[cirr]

Shanghai researchers make breakthrough in power-generating fabrics

2019-02-26 16:19:42 chinadaily.com.cn Editor : Jing Yuxin

A demonstration of how the power-generating fabrics are woven and work with wearable devices. (Photo provided to chinadaily.com.cn)

A research team at Donghua University in Shanghai has uncovered a way to achieve the continuous and scalable manufacture of amphibious energy yarns and textiles, which could pave the way for smart clothing.

A paper titled Continuous and Scalable Manufacture of Amphibious Energy Yarns and Textiles was published on Nature Communications, an international peer-reviewed scientific journal, on Feb 22.

According to Gong Wei, the first author of the paper, the amphibious energy yarns and textiles are composed of highly elastic polymer materials (rubber) and spiral metal fibers. The two materials produce an electro-transfer reaction during any deformation before generating power.

With the help of core-sheath structure and gain-coupled power generation mechanism, researchers found that the amphibious energy yarns and textiles can be self-generating without interaction with other objects, and can be used in various situations, even in liquids.

Hou Chengyi, associate professor of the team and school of materials science and engineering at Donghua University, said the special yearns and textiles can be made into elastic power-generating fabrics.

Power-generating yarns can also be woven with other fibers, such as nylon fiber and polyacrylonitrile fibers, so that the breathability, comfort level and power generation of textiles can be effectively controlled.

http://www.ecns.cn/news/2019-02-26/detail-ifzevinw9629759.shtml

 

[JSCh]

Deep-time Digital Earth aims to liberate data from collections such as the British Geological Survey’s.
BRITISH GEOLOGICAL SURVEY
Earth scientists plan to meld massive databases into a ‘geological Google’ | Science | AAAS
By Dennis Normile Feb. 26, 2019 , 5:00 PM

The British Geological Survey (BGS) has amassed one of the world’s premier collections of geologic samples. Housed in three enormous warehouses in Nottingham, U.K., it contains about 3 million fossils gathered over more than 150 years at thousands of sites across the country. But this data trove “was not really very useful to anybody,” says Michael Stephenson, a BGS paleontologist. Notes about the samples and their associated rocks “were sitting in boxes on bits of paper.” Now, that could change, thanks to a nascent international effort to meld earth science databases into what Stephenson and other backers are describing as a “geological Google.”

This network of earth science databases, called Deep-time Digital Earth (DDE), would be a one-stop link allowing earth scientists to access all the data they need to tackle big questions, such as patterns of biodiversity over geologic time, the distribution of metal deposits, and the workings of Africa’s complex groundwater networks. It’s not the first such effort, but it has a key advantage, says Isabel Montañez, a geochemist at University of California, Davis, who is not involved in the project: funding and infrastructure support from the Chinese government. That backing “will be critical to [DDE’s] success given the scope of the proposed work,” she says.

In December 2018, DDE won the backing of the executive committee of the International Union of Geological Sciences, which said ready access to the collected geodata could offer “insights into the distribution and value of earth’s resources and materials, as well as hazards—while also providing a glimpse of the Earth’s geological future.” At a meeting this week in Beijing, 80 scientists from 40 geoscience organizations including BGS and the Russian Geological Research Institute are discussing how to get DDE up and running by the time of the International Geological Congress in New Delhi in March 2020.

DDE grew out of a Chinese data digitization scheme called the Geobiodiversity Database (GBDB), initiated in 2006 by Chinese paleontologist Fan Junxuan of Nanjing University. China had long-running efforts in earth sciences, but the data were scattered among numerous collections and institutions. Fan, who was then at the Chinese Academy of Sciences’s Nanjing Institute of Geology and Paleontology, organized GBDB around the stacks of geologic strata called sections and the rocks and fossils in each stratum.

Norman MacLeod, a paleobiologist at the Natural History Museum in London who is advising DDE, says GBDB has succeeded where similar efforts have stumbled. In the past, he says, volunteer earth scientists tried to do nearly everything themselves, including informatics and data management. GBDB instead pays nonspecialists to input reams of data gleaned from earth science journals covering Chinese findings. Then, paleontologists and stratigraphers review the data for accuracy and consistency, and information technology specialists curate the database and create software to search and analyze the data. Consistent funding also contributed to GBDB’s success, MacLeod says. Although it started small, Fan says GBDB now runs on “several million” yuan per year.

Earth scientists outside China began to use GBDB, and it became the official database of the International Commission on Stratigraphy in 2012. BGS decided to partner with GBDB to lift its data “from the page and into cyberspace,” as Stephenson puts it. He and other European and Chinese scientists then began to wonder whether the informatics tools developed for GBDB could help create a broader union of databases. “Our idea is to take these big databases and make them use the same standards and references so a researcher could quickly link them to do big science that hasn’t been done before,” he says.

The Beijing meeting aims to finalize an organizational structure for DDE. Chinese funding agencies are putting up $75 million over 10 years to get the effort off the ground, Fan says. That level of support sets DDE apart from other cyberinfrastructure efforts “that are smaller in scope and less well funded,” Montañez says. Fan hopes DDE will also attract international support. He envisions nationally supported DDE Centers of Excellence that would develop databases and analytical tools for particular interests. Suzhou, China, has already agreed to host the first of them, which will also house the DDE secretariat.

DDE backers say they want to cooperate with other geodatabase programs, such as BGS’s OneGeology project, which seeks to make geologic maps of the world available online. But Mohan Ramamurthy, project director of the U.S. National Science Foundation–funded EarthCube project, sees little scope for collaboration with his effort, which focuses on current issues such as climate change and biosphere-geosphere interactions. “The two programs have very different objectives with little overlap,” he says.

Fan also hopes individual institutions will contribute, by sharing data, developing analytical tools, and encouraging their scientists to participate. Once earth scientists are freed of the drudgery of combing scattered collections, he says, they will have time for more important challenges, such as answering “questions about the evolution of life, materials, geography, and climate in deep time.”

 

[JSCh]

PUBLIC RELEASE: 28-FEB-2019
Nanotechnology makes it possible for mice to see in infrared
CELL PRESS

Mice with vision enhanced by nanotechnology were able to see infrared light as well as visible light, reports a study published February 28 in the journal Cell. A single injection of nanoparticles in the mice's eyes bestowed infrared vision for up to 10 weeks with minimal side effects, allowing them to see infrared light even during the day and with enough specificity to distinguish between different shapes. These findings could lead to advancements in human infrared vision technologies, including potential applications in civilian encryption, security, and military operations.

Humans and other mammals are limited to seeing a range of wavelengths of light called visible light, which includes the wavelengths of the rainbow. But infrared radiation, which has a longer wavelength, is all around us. People, animals and objects emit infrared light as they give off heat, and objects can also reflect infrared light.

"The visible light that can be perceived by human's natural vision occupies just a very small fraction of the electromagnetic spectrum," says senior author Tian Xue of the University of Science and Technology of China. "Electromagnetic waves longer or shorter than visible light carry lots of information."

A multidisciplinary group of scientists led by Xue and Jin Bao at the University of Science and Technology of China as well as Gang Han at the University of Massachusetts Medical School, developed the nanotechnology to work with the eye's existing structures.

"When light enters the eye and hits the retina, the rods and cones--or photoreceptor cells--absorb the photons with visible light wavelengths and send corresponding electric signals to the brain," says Han. "Because infrared wavelengths are too long to be absorbed by photoreceptors, we are not able to perceive them."

In this study, the scientists made nanoparticles that can anchor tightly to photoreceptor cells and act as tiny infrared light transducers. When infrared light hits the retina, the nanoparticles capture the longer infrared wavelengths and emit shorter wavelengths within the visible light range. The nearby rod or cone then absorbs the shorter wavelength and sends a normal signal to the brain, as if visible light had hit the retina.

"In our experiment, nanoparticles absorbed infrared light around 980 nm in wavelength and converted it into light peaked at 535 nm, which made the infrared light appear as the color green," says Bao.

The researchers tested the nanoparticles in mice, which, like humans, cannot see infrared naturally. Mice that received the injections showed unconscious physical signs that they were detecting infrared light, such as their pupils constricting, while mice injected with only the buffer solution didn't respond to infrared light.

To test whether the mice could make sense of the infrared light, the researchers set up a series of maze tasks to show the mice could see infrared in daylight conditions, simultaneously with visible light.

In rare cases, side effects from the injections such as cloudy corneas occurred but disappeared within less than a week. This may have been caused by the injection process alone because mice that only received injections of the buffer solution had a similar rate of these side effects. Other tests found no damage to the retina's structure following the sub-retinal injections.

"In our study, we have shown that both rods and cones bind these nanoparticles and were activated by the near infrared light," says Xue. "So we believe this technology will also work in human eyes, not only for generating super vision but also for therapeutic solutions in human red color vision deficits."

Current infrared technology relies on detectors and cameras that are often limited by ambient daylight and need outside power sources. The researchers believe the bio-integrated nanoparticles are more desirable for potential infrared applications in civilian encryption, security, and military operations. "In the future, we think there may be room to improve the technology with a new version of organic-based nanoparticles, made of FDA-approved compounds, that appear to result in even brighter infrared vision," says Han.

The researchers also think more work can be done to fine tune the emission spectrum of the nanoparticles to suit human eyes, which utilize more cones than rods for their central vision compared to mouse eyes. "This is an exciting subject because the technology we made possible here could eventually enable human beings to see beyond our natural capabilities," says Xue.



Nanotechnology makes it possible for mice to see in infrared | EurekAlert! Science News

Yuqian Ma; Jin Bao; Yuanwei Zhang; Zhanjun Li; Xiangyu Zhou; Changlin Wan; Ling Huang; Yang Zhao; Gang Han; Tian Xue. Mammalian Near-Infrared Image Vision through Injectable and Self-Powered Retinal Nanoantennae. Cell (2019). DOI: 10.1016/j.cell.2019.01.038​

 

[JSCh]

EDITORIAL * 27 FEBRUARY 2019
Data mining uncovers a treasure trove of topological materials | Nature
Sharing experimental data enhances materials discovery and engineering.

The band structure of graphene determines whether it will act as a topological semi-metal (left) or a topological insulator (right).Credit: B. Bradlyn et al.

Collaborative efforts to develop centralized databases have become common in some fields. To be useful, databases need appropriate support and to be annotated using standardized approaches. Whether time and resources are well spent on these tasks depends on the value gained from exploring vast data repositories.

Three papers in Nature this week show that materials science is reaping the rewards of such investment (see T. Zhang et al., M. G. Vergniory et al. and F. Tang et al.). The teams developed algorithms to scan through tens of thousands of non-magnetic materials catalogued in crystal-structure databases and, astonishingly, found that around one-quarter could be considered ‘topological’ — harbouring unusual states at their surfaces or edges that are caused by the geometry of their electronic structures.

The unusual properties of topological systems offer new possibilities for materials engineering, including the design of energy-efficient transistors and circuits. Yet only a few topological materials have been identified.

The findings in Nature are theoretical and, as physicist Alex Zunger points out in a Comment, many such materials might be difficult to synthesize, or could turn out not to have the predicted properties when tested experimentally. Even if researchers need to curb their enthusiasm down the line, the unimagined scale of this discovery was possible only because of the existence of large crystallographic databases.

Just as data sharing has facilitated these theoretical predictions, it will also benefit future materials discovery and engineering. But to achieve this, researchers will need to systematically release all underlying data. Topological catalogues are still in the early stages of development, so this community would do well not to miss the opportunity to push for widespread and standardized sharing of experimental data.

• Tiantian Zhang, Yi Jiang, Zhida Song, He Huang, Yuqing He, Zhong Fang, Hongming Weng & Chen Fang. Catalogue of topological electronic materials. Nature (2019). DOI: 10.1038/s41586-019-0944-6
• M. G. Vergniory, L. Elcoro, Claudia Felser, Nicolas Regnault, B. Andrei Bernevig & Zhijun Wang. A complete catalogue of high-quality topological materials. Nature (2019). DOI: 10.1038/s41586-019-0954-4
• Feng Tang, Hoi Chun Po, Ashvin Vishwanath & Xiangang Wan. Comprehensive search for topological materials using symmetry indicators. Nature (2019). DOI: 10.1038/s41586-019-0937-5

 

[JSCh]

CRISPR offshoot still makes mistakes editing DNA, raising concerns about its medical use
By Jon Cohen Feb. 28, 2019 , 2:00 PM

Variations of the genome editor CRISPR have wowed biology labs around the world over the past few years because they can precisely change single DNA bases, promising deft repairs for genetic diseases and improvements in crop and livestock genomes. But such “base editors” can have a serious weakness. A pair of studies published online in Science this week shows that one kind of base editor causes many unwanted—and potentially dangerous—“off-target” genetic changes.

The mistakes are still rare overall, says David Liu, a chemist at Harvard University whose team developed the first generation of base editors, and are unlikely to interfere with laboratory uses of the technology. But they are enough to concern anyone contemplating use of the technology in patients, Liu and others say. “The two papers are very interesting and important,” says Jin-Soo Kim, a CRISPR researcher at Seoul National University. “It is now important to determine which component is responsible for the collateral mutations and how to reduce or avoid them.”

In its original form, CRISPR uses an RNA strand to guide an enzyme known as Cas9 to a specific place in a genome. The Cas9 acts as a molecular scissors on the DNA, cutting both of its strands, and the cell’s attempts to repair the brake can disable the gene. Or researchers can use the cut to insert a new sequence of DNA. Base editors instead couple the guide RNA to a Cas9 that only cuts one DNA strand. This molecular complex also includes an enzyme, called a deaminase, that can chemically change one base into another. Because such editors have more control over the specific changes than CRISPR itself, researchers did not expect them to cause off-target errors.

Now, two groups of researchers mainly based in China, working independently on rice and on mouse embryos, have discovered abundant off-target mutations in experiments that used an editor that changes the DNA base cytosine to thymine. A second base editor, also from Liu’s team, that converts adenine to guanine introduced no such mistakes.

In the rice study, a team led by plant biologist Gao Caixia of the Chinese Academy of Sciences (CAS) in Beijing compared the DNA in 77 plants it had altered with different base editors to sham controls or untreated plants. The researchers then assessed the low-level background mutation rates. They found that cytosine-to-thymine base editors roughly doubled the background level of off-target mutations. “We were so surprised, and worried we had to be really, really careful with our results because the whole world will be looking closely,” Gao says. “Fortunately, the other group worked with the mouse and made a very similar observation, and their system, to be honest, is even better than ours.”

In that work, a multi-institution collaboration led by researchers from CAS in Shanghai and Stanford University in Palo Alto, California, developed a clever built-in control by injecting a base editor into only one of two cells in a newly formed mouse embryo. Comparing the progeny of these two cells, researchers found the off-target effects created by the cytosine base editor were more than 20 times more common than the background mutation rate. Some of the mutations occurred in genomic regions that play a role in cancer.

Tweaking that editor’s deaminase or other components could decrease its off-target effects, says J. Keith Joung, a pathologist at Massachusetts General Hospital in Boston who invented a popular cytosine base editor and co-founded both a biomedical and an agricultural base editor company with Liu. Kim is optimistic that the field will promptly figure out solutions for the cytosine editors. “A new problem always provides new opportunities,” he says.

Stanley Qi, a Stanford University bioengineer who has created a variation of CRISPR as well, says it’s no surprise that a new biotechnology has imperfections. “I don’t think these reports diminish my enthusiasm towards base editors or gene editing.”



CRISPR offshoot still makes mistakes editing DNA, raising concerns about its medical use | Science | AAAS

• Shuai Jin, Yuan Zong, Qiang Gao, Zixu Zhu, Yanpeng Wang, Peng Qin, Chengzhi Liang, Daowen Wang, Jin-Long Qiu, Feng Zhang, Caixia Gao. Cytosine, but not adenine, base editors induce genome-wide off-target mutations in rice. Science (2019). DOI: 10.1126/science.aaw7166
• Erwei Zuo, Yidi Sun, Wu Wei, Tanglong Yuan, Wenqin Ying, Hao Sun, Liyun Yuan, Lars M. Steinmetz, Yixue Li, Hui Yang. Cytosine base editor generates substantial off-target single-nucleotide variants in mouse embryos. Science (2019). DOI: 10.1126/science.aav9973

 

[JSCh]

Chinese scientists find therapeutic target of common liver cancer
Source: Xinhua| 2019-02-28 22:46:25|Editor: zh

BEIJING, Feb. 28 (Xinhua) -- Chinese scientists have identified a therapeutic target of early-stage hepatocellular carcinoma (HCC), the most common type of primary liver cancer in adults.

HCC is the third leading cause of cancer-related deaths worldwide. Infection with the hepatitis B virus is one of the leading risk factors for developing HCC, particularly in East Asia, according to He Fuchu, chief scientist of the Chinese Human Proteome Project and an academician of the Chinese Academy of Sciences.

Although surgical treatment may be effective in the early stages, the five-year overall rate of survival after developing this cancer is only 50 percent to 70 percent, according to scientists.

Researchers classified the cancer into three sub-types S-I, S-II and S-III. Each of the three sub-types has a different clinical outcome, with S-III associated with the lowest overall rate of survival.

By analyzing the proteomic data of the S-III sub-type, scientists found the therapeutic target called SOAT1. The knockdown of SOAT1 can effectively suppress the proliferation and migration of HCC.

In experiments on mice, they also found that treatment with avasimibe, an inhibitor of SOAT1, markedly reduced the size of tumors that had high levels of SOAT1 expression.

The study provides insight into the tumor biology of this cancer, and suggests opportunities for personalized therapies that target it, He said.

The research was published in the latest issue of the academic journal Nature.

Ying Jiang, Aihua Sun, Yang Zhao, Wantao Ying, Huichuan Sun, Xinrong Yang, Baocai Xing, Wei Sun, Liangliang Ren, Bo Hu, Chaoying Li, Li Zhang, Guangrong Qin, Menghuan Zhang, Ning Chen, Manli Zhang, Yin Huang, Jinan Zhou, Yan Zhao, Mingwei Liu, Xiaodong Zhu, Yang Qiu, Yanjun Sun, Cheng Huang, Meng Yan, Mingchao Wang, Wei Liu, Fang Tian, Huali Xu, Jian Zhou, Zhenyu Wu, Tieliu Shi, Weimin Zhu, Jun Qin, Lu Xie, Jia Fan, Xiaohong Qian, Fuchu He & Chinese Human Proteome Project (CNHPP) Consortium. Proteomics identifies new therapeutic targets of early-stage hepatocellular carcinoma. Nature (2019). DOI: 10.1038/s41586-019-0987-8​

 

[JSCh]

PUBLIC RELEASE: 28-FEB-2019
Nanotechnology makes it possible for mice to see in infrared
CELL PRESS

Mice with vision enhanced by nanotechnology were able to see infrared light as well as visible light, reports a study published February 28 in the journal Cell. A single injection of nanoparticles in the mice's eyes bestowed infrared vision for up to 10 weeks with minimal side effects, allowing them to see infrared light even during the day and with enough specificity to distinguish between different shapes. These findings could lead to advancements in human infrared vision technologies, including potential applications in civilian encryption, security, and military operations.

Humans and other mammals are limited to seeing a range of wavelengths of light called visible light, which includes the wavelengths of the rainbow. But infrared radiation, which has a longer wavelength, is all around us. People, animals and objects emit infrared light as they give off heat, and objects can also reflect infrared light.

"The visible light that can be perceived by human's natural vision occupies just a very small fraction of the electromagnetic spectrum," says senior author Tian Xue of the University of Science and Technology of China. "Electromagnetic waves longer or shorter than visible light carry lots of information."

A multidisciplinary group of scientists led by Xue and Jin Bao at the University of Science and Technology of China as well as Gang Han at the University of Massachusetts Medical School, developed the nanotechnology to work with the eye's existing structures.

"When light enters the eye and hits the retina, the rods and cones--or photoreceptor cells--absorb the photons with visible light wavelengths and send corresponding electric signals to the brain," says Han. "Because infrared wavelengths are too long to be absorbed by photoreceptors, we are not able to perceive them."

In this study, the scientists made nanoparticles that can anchor tightly to photoreceptor cells and act as tiny infrared light transducers. When infrared light hits the retina, the nanoparticles capture the longer infrared wavelengths and emit shorter wavelengths within the visible light range. The nearby rod or cone then absorbs the shorter wavelength and sends a normal signal to the brain, as if visible light had hit the retina.

"In our experiment, nanoparticles absorbed infrared light around 980 nm in wavelength and converted it into light peaked at 535 nm, which made the infrared light appear as the color green," says Bao.

The researchers tested the nanoparticles in mice, which, like humans, cannot see infrared naturally. Mice that received the injections showed unconscious physical signs that they were detecting infrared light, such as their pupils constricting, while mice injected with only the buffer solution didn't respond to infrared light.

To test whether the mice could make sense of the infrared light, the researchers set up a series of maze tasks to show the mice could see infrared in daylight conditions, simultaneously with visible light.

In rare cases, side effects from the injections such as cloudy corneas occurred but disappeared within less than a week. This may have been caused by the injection process alone because mice that only received injections of the buffer solution had a similar rate of these side effects. Other tests found no damage to the retina's structure following the sub-retinal injections.

"In our study, we have shown that both rods and cones bind these nanoparticles and were activated by the near infrared light," says Xue. "So we believe this technology will also work in human eyes, not only for generating super vision but also for therapeutic solutions in human red color vision deficits."

Current infrared technology relies on detectors and cameras that are often limited by ambient daylight and need outside power sources. The researchers believe the bio-integrated nanoparticles are more desirable for potential infrared applications in civilian encryption, security, and military operations. "In the future, we think there may be room to improve the technology with a new version of organic-based nanoparticles, made of FDA-approved compounds, that appear to result in even brighter infrared vision," says Han.

The researchers also think more work can be done to fine tune the emission spectrum of the nanoparticles to suit human eyes, which utilize more cones than rods for their central vision compared to mouse eyes. "This is an exciting subject because the technology we made possible here could eventually enable human beings to see beyond our natural capabilities," says Xue.



Nanotechnology makes it possible for mice to see in infrared | EurekAlert! Science News

Yuqian Ma; Jin Bao; Yuanwei Zhang; Zhanjun Li; Xiangyu Zhou; Changlin Wan; Ling Huang; Yang Zhao; Gang Han; Tian Xue. Mammalian Near-Infrared Image Vision through Injectable and Self-Powered Retinal Nanoantennae. Cell (2019). DOI: 10.1016/j.cell.2019.01.038​

Scientists Enable Super Mice to See Infrared Light

Beauty of Science
Published on Feb 28, 2019

Science fiction is becoming a reality. We created this short animation for researchers at the University of Science and Technology of China and the University of Massachusetts. They used special nanoparticles to allow mice to see in the near-infrared range without compromising their normal vision.

 

[JSCh]

Chinese researchers find new target for tumor immunotherapy
Source: Xinhua| 2019-03-05 00:02:56|Editor: Mu Xuequan

BEIJING, March 4 (Xinhua) -- A team of Chinese researchers has identified a transcription factor that affects the immunologic effects of T cells, providing a new potential target for tumor immunotherapy.

T cells are often called "the workhorses of the immune system" for their critical role in orchestrating the immune response and killing cells infected by pathogens.

One emerging immunotherapy in recent years is CAR-T cells therapy. It separates T cells from a patient's blood and genetically engineers them to produce receptors on their surface called chimeric antigen receptors or CARs. The special receptors allow T cells to recognize and attach to tumor cells. When the CAR-T cells are infused back into the patient, the engineered cells will multiply in the patient's body and recognize and kill cancer cells.

However, previous studies found that some T cells can be dysfunctional when they encounter self-antigens or are exposed to chronic infection or tumor microenvironment.

To reveal the molecular mechanism behind T cells dysfunction, researchers from China's Third Military Medical University and Tsinghua University used an in vitro T cell tolerance induction system in mice and found a high-level expression of transcription factor NR4A1.

NR4A1 is the transcription factor of the nuclear receptor NR4A. Nuclear receptors are a class of proteins that can work with other proteins to regulate the expression of specific genes. A transcription factor is a protein that binds to specific DNA sequences, thereby controlling the rate of transcription of genetic information from DNA to messenger RNA.

The researchers reported on the British journal Nature that over-expression of NR4A1 inhibits T cell function and deletion of NR4A1 overcame T cell tolerance and enhanced immunity against tumor and chronic virus.

They said that the study identified NR4A1 as a key general regulator in the induction of T cell dysfunction, and a potential target for tumor immunotherapy.

In recent years, immunotherapy, therapies that enlist and strengthen the power of a patient's immune system to attack tumors, has emerged as a new cancer treatment.

In 2017, two CAR-T cell therapies were approved by the U.S. Food and Drug Administration, one for the treatment of children with acute lymphoblastic leukemia and the other for adults with advanced lymphomas.

 

[JSCh]

PUBLIC RELEASE: 20-FEB-2019
Powering a pacemaker with a patient's heartbeat
AMERICAN CHEMICAL SOCIETY

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A small, flexible device can power a pacemaker with energy from heartbeats.
CREDIT: American Chemical Society

Implantable pacemakers have without doubt altered modern medicine, saving countless lives by regulating heart rhythm. But they have one serious shortcoming: Their batteries last only five to 12 years, at which point they have to be replaced surgically. Now, researchers have surmounted this issue by designing a pacemaker powered by the energy of heartbeats, according to a report in ACS Nano. The device was successfully tested in pigs, which have a similar physiology to humans.

A conventional pacemaker is implanted just under the skin near the collarbone. Its battery and circuitry generate electrical signals that are delivered to the heart via implanted electrodes. Because surgery to replace the battery can lead to complications, including infection and bleeding, various researchers have tried to build pacemakers that use the natural energy of heartbeats as an alternative energy source. However, these experimental devices aren't powerful enough because of their rigid structure, difficulties with miniaturization and other drawbacks, so Hao Zhang, Bin Yang and colleagues searched for ways to improve the technology.

First, they designed a small, flexible plastic frame. Next they bonded the frame to piezoelectric layers, which generate energy when bent. They implanted the device in pigs and showed that a beating heart could in fact alter the frame's shape, generating enough power to match the performance of a battery-powered pacemaker. The study is a step toward making a self-powered cardiac pacemaker, the researchers say.


Powering a pacemaker with a patient's heartbeat | EurekAlert! Science News

Ning Li, Zhiran Yi, Ye Ma, Feng Xie, Yue Huang, Yingwei Tian, Xiaoxue Dong, Yang Liu, Xin Shao, Yang Li, Lei Jin, Jingquan Liu , Zhiyun Xu, Bin Yang and Hao Zhang. Direct Powering a Real Cardiac Pacemaker by Natural Energy of a Heartbeat. ACS Nano (2019). DOI: 10.1021/acsnano.8b08567​

 

[JSCh]

Study reveals how cell "gatekeeper" activates immune defense
Source: Xinhua| 2019-03-01 15:40:23|Editor: Li Xia

BEIJING, March 1 (Xinhua) -- Recent Chinese research has found how cGAS (cyclic GMP-AMP synthase), an enzyme and DNA sensor dubbed as a cell's gatekeeper, activates immune responses when the body has a viral infection, providing new perspectives for treatments of some autoimmune diseases.

The recognition of microbial nucleic acids is a major mechanism by which the immune system detects pathogens. cGAS is a DNA sensor in the cytosol that activates innate immune responses. It not only plays a key role in mediating protective immune defense against infection by many DNA-containing pathogens but also detects tumor-derived DNA and generates intrinsic anti-tumor immunity.

However, aberrant activation of the cGAS pathway can also lead to autoimmune and inflammatory diseases.

In autoimmune diseases, the cell nucleus spits small DNA fragments into the cytoplasm or the cells have difficulty breaking down DNA from dead cells. DNA fragments, therefore, accumulate in the cytoplasm and the immune system cells start fighting themselves instead of pathogens from the outside.

In recent years, scientists have been trying to understand how cGAS activates immune responses and whether blocking or regulating the pathway may have an effect on autoimmune diseases.

In a paper published online in the U.S. journal Cell, researchers from China's Academy of Military Medical Sciences reported that acetylation inhibits cGAS activation. It is found that aspirin can directly acetylate cGAS and efficiently inhibit cGAS-mediated immune responses.

Acetylation is a chemical reaction that most of the proteins in the human body undergo. The process of acetylation is important for several main chemical reactions in the body like protein formation and drug bio-transformation.

In lab experiments, the researchers found that aspirin can effectively suppress self-DNA-induced autoimmunity in Aicardi-Goutieres syndrome (AGS) patient cells and in an AGS mouse model.

AGS is a rare inflammatory disorder most typically affecting the brain and the skin. The majority of affected individuals experience significant intellectual and physical problems.

The researchers said their study reveals that acetylation contributes to cGAS activity regulation and provides a potential therapy for treating DNA-mediated autoimmune diseases.

 

[JSCh]

Baby receives stem cell transplant for rare immunity disorder
Cai Wenjun 16:13 UTC+8, 2019-03-04

Staff from the Shanghai-based China Stem Cell Group Co take a sample of umbilical cord blood to the Children's Hospital of Fudan University for an 8-month-old girl with congenital immunity disorder to receive stem cell transplant on Monday.

An 8-month-old girl received a stem cell transplant on Monday at a local hospital to treat a rare congenital disease, marking the 4,000th stem cell transplant conducted by the Shanghai-based China Stem Cell Group Co.

The girl, a Hunan Province native, suffers a genetic disorder called severe combined immunodeficiency, which is known as the bubble boy disease because its victims are likely to suffer infection and some, such as David Vetter, become famous for living in an extremely sterile environment.

The disease usually results in serious infections within the first few months upon delivery, and most children die within one year due to infection. Stem cell transplant is an effective way to treat the disease which helps rebuild their immune system, according to doctors from the Children’s Hospital of Fudan University.

“We have treated 30 such cases and 80 percent of the patients have survived. There is a big hope that the patient can be cured after a successful stem cell transplant,” said Dr Qian Xiaowen from the hospital.

The girl’s family said they are blessed that the girl may be saved.

“My daughter started to have frequent fevers when she was 4 months old and was confirmed to have the rare disease later,” said the father, surnamed Zhang. “We are so happy we found a match at the umbilical cord blood bank. If everything goes smoothly, my daughter is expected to be discharged in late April.”

The 8-month-old girl with severe combined immunodeficiency with her mother

Source: SHINE Editor: Cai Wenjun