In the past several years, scientists have created antibacterial surfaces by fabricating materials with specific types of nanostructures. According to a May 27, 2020 news item on Nanowerk, scientists have now been able to add antiviral properties (Note: A link has been removed),
The novel coronavirus pandemic has caused an increased demand for antimicrobial treatments that can keep surfaces clean, particularly in health care settings. Although some surfaces have been developed that can combat bacteria, what’s been lacking is a surface that can also kill off viruses.
Now, researchers have found a way to impart durable antiviral and antibacterial properties to an aluminum alloy used in hospitals, according to a report in ACS Biomaterials Science & Engineering (“Antiviral and Antibacterial Nanostructured Surfaces with Excellent Mechanical Properties for Hospital Applications”).
Among other mechanisms, viruses and bacteria can spread when a person touches a site where germs have settled, such as a doorframe, handrail or medical device. A healthy person can often fight off these bugs, but hospital patients can be more vulnerable to infection. The number of hospital-acquired infections has been on the decline in the U.S., but they still cause tens of thousands of deaths every year, according to the U.S. Department of Health and Human Services. Chemical disinfectants or coatings containing hydrophobic compounds, silver ions or copper can reduce infectious contaminants on surfaces, but these treatments don’t last. However, nature has developed its own solutions for battling microorganisms, including microscopic structural features that render some insect wings lethal to bacteria. Scientists have replicated this effect by forming surfaces covered with minute pillars and other shapes that distort and kill bacterial cells. But Prasad Yarlagadda and colleagues wanted to inactivate viruses as well as bacteria, so they set out to generate a novel nanoscale topography on long-lasting, industrially relevant materials.
The team experimented with disks of aluminum 6063, which is used in doorframes, window panels, and hospital and medical equipment. Etching the disks with sodium hydroxide for up to 3 hours changed the initially smooth, hydrophobic surface into a ridged, hydrophilic surface. Bacteria or viruses were then applied to the etched disks. Most of the Pseudomonas aeruginosa and Staphylococcus aureus bacteria were inactivated after 3 hours on the surface, while viability of common respiratory viruses dropped within 2 hours; both results were better than with plastic or smooth aluminum surfaces. The disks retained their effectiveness even after tests designed to mimic hospital wear and tear. The researchers note this is the first report to show combined antibacterial and antiviral properties of a durable, nanostructured surface that has the potential to stop the spread of infections arising from physical surfaces in hospitals. This strategy could be extended to surfaces in other public areas, such as cruise ships, planes and airports, they say. The team is now studying the effects of their nano-textured aluminum surfaces on the novel coronavirus.
This approach reminds me of Sharklet, a company fabricating a material designed to mimic a shark’s skin which is naturally antibacterial due to the nanostructures on its skin (see my September 18, 2014 posting).
More about Sharklet later. First, here’s a link to and a citation for the paper about this latest work,
Sharklet Technologies, Inc., a biotechnology company lauded for the creation and commercialization of Sharklet®, the world’s first micro-texture that inhibits bacterial growth on surfaces, has announced that it has completed a financing event led by Peaceful Union, an equity medical device firm in Hangzhou, China. Terms of the transaction were not disclosed.
The acquisition of the company will enable Sharklet Technologies to accelerate the development of Sharklet for medical devices where chemical-free bacterial inhibition is desired as well as high-touch surfaces prone to bacterial contamination. The company also will accelerate development of a newly enhanced wound dressing technology to encourage healing.
Joe Bagan and Mark Spiecker led the transaction structure. “This is an important day for the company and investors,” said Joe Bagan, former board chair, and Mark Spiecker, former CEO. “Our investors will realize a significant transaction while enabling the company to accelerate growth.”
In concert with the investment, Sharklet Technologies founding member, chief technology officer, and Sharklet inventor Dr. Anthony Brennan, will become chairman of the board assuming duties from chairman Joe Bagan and CEO Mark Spiecker.
Interestingly, Bagan and Spiecker are Chief Executive Officer (CEO) and President, respectively at STAQ Pharma. I wonder if there are plans to sell this company too.
Getting back to Sharklet, I found two items of recent origin about business but I cannot speak to the accuracy or trustworthiness of either item. That said, you will find they provide some detail about Sharklet’s new business directions and new business ties.
While Sharklet’s current business associations have a sketchy quality, it seems that’s not unusual in business, especially where new technologies are concerned. For example, the introduction of electricity into homes and businesses was a tumultuous affair as the 2008 book, ‘Power Struggles; Scientific Authority and the Creation of Practical Electricity Before Edison’ by Michael Brian Schiffer makes clear, from the MIT [Massachusetts Institute of Technology] Press ‘Power Struggles’ webpage,
In 1882, Thomas Edison and his Edison Electric Light Company unveiled the first large-scale electrical system in the world to light a stretch of offices in a city. … After laying out a unified theoretical framework for understanding technological change, Schiffer presents a series of fascinating case studies of pre-Edison electrical technologies, including Volta’s electrochemical battery, the blacksmith’s electric motor, the first mechanical generators, Morse’s telegraph, the Atlantic cable, and the lighting of the Capitol dome. Schiffer discusses claims of “practicality” and “impracticality” (sometimes hotly contested) made for these technologies, and examines the central role of the scientific authority—in particular, the activities of Joseph Henry, mid-nineteenth-century America’s foremost scientist—in determining the fate of particular technologies. These emerging electrical technologies formed the foundation of the modern industrial world. Schiffer shows how and why they became commercial products in the context of an evolving corporate capitalism in which conflicting judgments of practicality sometimes turned into power struggles. [emphases mine]
Even given that the book’s focus is pre-Edison electricity, how do you mention Edison himself without even casually mentioning Nikola Tesla and George Westinghouse in the book’s overview? Getting back to my point, emerging technologies do not emerge easily.
Artificial Neural Network (ANN) is a type of information processing system based on mimicking the principles of biological brains, and has been broadly applied in application domains such as pattern recognition, automatic control, signal processing, decision support system and artificial intelligence. Spiking Neural Network (SNN) is a type of biologically-inspired ANN that perform information processing based on discrete-time spikes. It is more biologically realistic than classic ANNs, and can potentially achieve much better performance-power ratio. Recently, researchers from Zhejiang University and Hangzhou Dianzi University in Hangzhou, China successfully developed the Darwin Neural Processing Unit (NPU), a neuromorphic hardware co-processor based on Spiking Neural Networks, fabricated by standard CMOS technology.
With the rapid development of the Internet-of-Things and intelligent hardware systems, a variety of intelligent devices are pervasive in today’s society, providing many services and convenience to people’s lives, but they also raise challenges of running complex intelligent algorithms on small devices. Sponsored by the college of Computer science of Zhejiang University, the research group led by Dr. De Ma from Hangzhou Dianzi university and Dr. Xiaolei Zhu from Zhejiang university has developed a co-processor named as Darwin.The Darwin NPU aims to provide hardware acceleration of intelligent algorithms, with target application domain of resource-constrained, low-power small embeddeddevices. It has been fabricated by 180nm standard CMOS process, supporting a maximum of 2048 neurons, more than 4 million synapses and 15 different possible synaptic delays. It is highly configurable, supporting reconfiguration of SNN topology and many parameters of neurons and synapses.Figure 1 shows photos of the die and the prototype development board, which supports input/output in the form of neural spike trains via USB port.
The successful development ofDarwin demonstrates the feasibility of real-time execution of Spiking Neural Networks in resource-constrained embedded systems. It supports flexible configuration of a multitude of parameters of the neural network, hence it can be used to implement different functionalities as configured by the user. Its potential applications include intelligent hardware systems, robotics, brain-computer interfaces, and others.Since it uses spikes for information processing and transmission,similar to biological neural networks, it may be suitable for analysis and processing of biological spiking neural signals, and building brain-computer interface systems by interfacing with animal or human brains. As a prototype application in Brain-Computer Interfaces, Figure 2 [not included here] describes an application example ofrecognizingthe user’s motor imagery intention via real-time decoding of EEG signals, i.e., whether he is thinking of left or right, and using it to control the movement direction of a basketball in the virtual environment. Different from conventional EEG signal analysis algorithms, the input and output to Darwin are both neural spikes: the input is spike trains that encode EEG signals; after processing by the neural network, the output neuron with the highest firing rate is chosen as the classification result.
The second generation of the Darwin Neural Processing Unit (Darwin NPU 2) as well as its corresponding toolchain and micro-operating system was released in Hangzhou recently. This research was led by Zhejiang University, with Hangzhou Dianzi University and Huawei Central Research Institute participating in the development and algorisms of the chip. The Darwin NPU 2 can be primarily applied to smart Internet of Things (IoT). It can support up to 150,000 neurons and has achieved the largest-scale neurons on a nationwide basis.
The Darwin NPU 2 is fabricated by standard 55nm CMOS technology. Every “neuromorphic” chip is made up of 576 kernels, each of which can support 256 neurons. It contains over 10 million synapses which can construct a powerful brain-inspired computing system.
“A brain-inspired chip can work like the neurons inside a human brain and it is remarkably unique in image recognition, visual and audio comprehension and naturalistic language processing,” said MA De, an associate professor at the College of Computer Science and Technology on the research team.
“In comparison with traditional chips, brain-inspired chips are more adept at processing ambiguous data, say, perception tasks. Another prominent advantage is their low energy consumption. In the process of information transmission, only those neurons that receive and process spikes will be activated while other neurons will stay dormant. In this case, energy consumption can be extremely low,” said Dr. ZHU Xiaolei at the School of Microelectronics.
To cater to the demands for voice business, Huawei Central Research Institute designed an efficient spiking neural network algorithm in accordance with the defining feature of the Darwin NPU 2 architecture, thereby increasing computing speeds and improving recognition accuracy tremendously.
Scientists have developed a host of applications, including gesture recognition, image recognition, voice recognition and decoding of electroencephalogram (EEG) signals, on the Darwin NPU 2 and reduced energy consumption by at least two orders of magnitude.
In comparison with the first generation of the Darwin NPU which was developed in 2015, the Darwin NPU 2 has escalated the number of neurons by two orders of magnitude from 2048 neurons and augmented the flexibility and plasticity of the chip configuration, thus expanding the potential for applications appreciably. The improvement in the brain-inspired chip will bring in its wake the revolution of computer technology and artificial intelligence. At present, the brain-inspired chip adopts a relatively simplified neuron model, but neurons in a real brain are far more sophisticated and many biological mechanisms have yet to be explored by neuroscientists and biologists. It is expected that in the not-too-distant future, a fascinating improvement on the Darwin NPU 2 will come over the horizon.
I haven’t been able to find a recent (i.e., post 2017) research paper featuring Darwin but there is another chip and research on that one was published in July 2019. First, the news.
The Tianjic chip
A July 31, 2019 article in the New York Times by Cade Metz describes the research and offers what seems to be a jaundiced perspective about the field of neuromorphic computing (Note: A link has been removed),
As corporate giants like Ford, G.M. and Waymo struggle to get their self-driving cars on the road, a team of researchers in China is rethinking autonomous transportation using a souped-up bicycle.
This bike can roll over a bump on its own, staying perfectly upright. When the man walking just behind it says “left,” it turns left, angling back in the direction it came.
It also has eyes: It can follow someone jogging several yards ahead, turning each time the person turns. And if it encounters an obstacle, it can swerve to the side, keeping its balance and continuing its pursuit.
… Chinese researchers who built the bike believe it demonstrates the future of computer hardware. It navigates the world with help from what is called a neuromorphic chip, modeled after the human brain.
Here’s a video, released by the researchers, demonstrating the chip’s abilities,
The short video did not show the limitations of the bicycle (which presumably tips over occasionally), and even the researchers who built the bike admitted in an email to The Times that the skills on display could be duplicated with existing computer hardware. But in handling all these skills with a neuromorphic processor, the project highlighted the wider effort to achieve new levels of artificial intelligence with novel kinds of chips.
This effort spans myriad start-up companies and academic labs, as well as big-name tech companies like Google, Intel and IBM. And as the Nature paper demonstrates, the movement is gaining significant momentum in China, a country with little experience designing its own computer processors, but which has invested heavily in the idea of an “A.I. chip.”
If you can get past what seems to be a patronizing attitude, there are some good explanations and cogent criticisms in the piece (Metz’s July 31, 2019 article, Note: Links have been removed),
… it faces significant limitations.
A neural network doesn’t really learn on the fly. Engineers train a neural network for a particular task before sending it out into the real world, and it can’t learn without enormous numbers of examples. OpenAI, a San Francisco artificial intelligence lab, recently built a system that could beat the world’s best players at a complex video game called Dota 2. But the system first spent months playing the game against itself, burning through millions of dollars in computing power.
Researchers aim to build systems that can learn skills in a manner similar to the way people do. And that could require new kinds of computer hardware. Dozens of companies and academic labs are now developing chips specifically for training and operating A.I. systems. The most ambitious projects are the neuromorphic processors, including the Tianjic chip under development at Tsinghua University in China.
Such chips are designed to imitate the network of neurons in the brain, not unlike a neural network but with even greater fidelity, at least in theory.
Neuromorphic chips typically include hundreds of thousands of faux neurons, and rather than just processing 1s and 0s, these neurons operate by trading tiny bursts of electrical signals, “firing” or “spiking” only when input signals reach critical thresholds, as biological neurons do.
Tiernan Ray’s August 3, 2019 article about the chip for ZDNet.com offers some thoughtful criticism with a side dish of snark (Note: Links have been removed),
Nature magazine’s cover story [July 31, 2019] is about a Chinese chip [Tianjic chip]that can run traditional deep learning code and also perform “neuromorophic” operations in the same circuitry. The work’s value seems obscured by a lot of hype about “artificial general intelligence” that has no real justification.
The term “artificial general intelligence,” or AGI, doesn’t actually refer to anything, at this point, it is merely a placeholder, a kind of Rorschach Test for people to fill the void with whatever notions they have of what it would mean for a machine to “think” like a person.
Despite that fact, or perhaps because of it, AGI is an ideal marketing term to attach to a lot of efforts in machine learning. Case in point, a research paper featured on the cover of this week’s Nature magazine about a new kind of computer chip developed by researchers at China’s Tsinghua University that could “accelerate the development of AGI,” they claim.
The chip is a strange hybrid of approaches, and is intriguing, but the work leaves unanswered many questions about how it’s made, and how it achieves what researchers claim of it. And some longtime chip observers doubt the impact will be as great as suggested.
“This paper is an example of the good work that China is doing in AI,” says Linley Gwennap, longtime chip-industry observer and principal analyst with chip analysis firm The Linley Group. “But this particular idea isn’t going to take over the world.”
The premise of the paper, “Towards artificial general intelligence with hybrid Tianjic chip architecture,” is that to achieve AGI, computer chips need to change. That’s an idea supported by fervent activity these days in the land of computer chips, with lots of new chip designs being proposed specifically for machine learning.
The Tsinghua authors specifically propose that the mainstream machine learning of today needs to be merged in the same chip with what’s called “neuromorphic computing.” Neuromorphic computing, first conceived by Caltech professor Carver Mead in the early ’80s, has been an obsession for firms including IBM for years, with little practical result.
[Missing details about the chip] … For example, the part is said to have “reconfigurable” circuits, but how the circuits are to be reconfigured is never specified. It could be so-called “field programmable gate array,” or FPGA, technology or something else. Code for the project is not provided by the authors as it often is for such research; the authors offer to provide the code “on reasonable request.”
More important is the fact the chip may have a hard time stacking up to a lot of competing chips out there, says analyst Gwennap. …
What the paper calls ANN and SNN are two very different means of solving similar problems, kind of like rotating (helicopter) and fixed wing (airplane) are for aviation,” says Gwennap. “Ultimately, I expect ANN [?] and SNN [spiking neural network] to serve different end applications, but I don’t see a need to combine them in a single chip; you just end up with a chip that is OK for two things but not great for anything.”
But you also end up generating a lot of buzz, and given the tension between the U.S. and China over all things tech, and especially A.I., the notion China is stealing a march on the U.S. in artificial general intelligence — whatever that may be — is a summer sizzler of a headline.
ANN could be either artificial neural network or something mentioned earlier in Ray’s article, a shortened version of CANN [continuous attractor neural network].
Shelly Fan’s August 7, 2019 article for the SingularityHub is almost as enthusiastic about the work as the podcasters for Nature magazine were (a little more about that later),
The study shows that China is readily nipping at the heels of Google, Facebook, NVIDIA, and other tech behemoths investing in developing new AI chip designs—hell, with billions in government investment it may have already had a head start. A sweeping AI plan from 2017 looks to catch up with the US on AI technology and application by 2020. By 2030, China’s aiming to be the global leader—and a champion for building general AI that matches humans in intellectual competence.
The country’s ambition is reflected in the team’s parting words.
“Our study is expected to stimulate AGI [artificial general intelligence] development by paving the way to more generalized hardware platforms,” said the authors, led by Dr. Luping Shi at Tsinghua University.
Using nanoscale fabrication, the team arranged 156 FCores, containing roughly 40,000 neurons and 10 million synapses, onto a chip less than a fifth of an inch in length and width. Initial tests showcased the chip’s versatility, in that it can run both SNNs and deep learning algorithms such as the popular convolutional neural network (CNNs) often used in machine vision.
Compared to IBM TrueNorth, the density of Tianjic’s cores increased by 20 percent, speeding up performance ten times and increasing bandwidth at least 100-fold, the team said. When pitted against GPUs, the current hardware darling of machine learning, the chip increased processing throughput up to 100 times, while using just a sliver (1/10,000) of energy.
Shelly Xuelai Fan is a neuroscientist-turned-science writer. She completed her PhD in neuroscience at the University of British Columbia, where she developed novel treatments for neurodegeneration. While studying biological brains, she became fascinated with AI and all things biotech. Following graduation, she moved to UCSF [University of California at San Francisco] to study blood-based factors that rejuvenate aged brains. She is the co-founder of Vantastic Media, a media venture that explores science stories through text and video, and runs the award-winning blog NeuroFantastic.com. Her first book, “Will AI Replace Us?” (Thames & Hudson) will be out April 2019.
Onto Nature. Here’s a link to and a citation for the paper,
Towards artificial general intelligence with hybrid Tianjic chip architecture by Jing Pei, Lei Deng, Sen Song, Mingguo Zhao, Youhui Zhang, Shuang Wu, Guanrui Wang, Zhe Zou, Zhenzhi Wu, Wei He, Feng Chen, Ning Deng, Si Wu, Yu Wang, Yujie Wu, Zheyu Yang, Cheng Ma, Guoqi Li, Wentao Han, Huanglong Li, Huaqiang Wu, Rong Zhao, Yuan Xie & Luping Shi. Nature volume 572, pages106–111(2019) DOI: https//doi.org/10.1038/s41586-019-1424-8 Published: 31 July 2019 Issue Date: 01 August 2019
This paper is behind a paywall.
The July 31, 2019 Nature podcast, which includes a segment about the Tianjic chip research from China, which is at the 9 mins. 13 secs. mark (AI hardware) or you can scroll down about 55% of the way to the transcript of the interview with Luke Fleet, the Nature editor who dealt with the paper.
The pundits put me in mind of my own reaction when I heard about phones that could take pictures. I didn’t see the point but, as it turned out, there was a perfectly good reason for combining what had been two separate activities into one device. It was no longer just a telephone and I had completely missed the point.
This too may be the case with the Tianjic chip. I think it’s too early to say whether or not it represents a new type of chip or if it’s a dead end.
Those are fabulous toes. Geckos and the fine hairs on their toes have been of great interest to researchers looking to increase qualities of adhesion for all kinds of purposes including for robots that climb. The latest foray into the research suggests that it’s not just the fine hairs found on gecko toes that are important.
Robots with toes? Experiments suggest that climbing robots could benefit from having flexible, hairy toes, like those of geckos, that can adjust quickly to accommodate shifting weight and slippery surfaces.
Biologists from the University of California, Berkeley, and Nanjing University of Aeronautics and Astronautics observed geckos running horizontally along walls to learn how they use their five toes to compensate for different types of surfaces without slowing down.
“The research helped answer a fundamental question: Why have many toes?” said Robert Full, UC Berkeley professor of integrative biology.
As his previous research showed, geckos’ toes can stick to the smoothest surfaces through the use of intermolecular forces, and uncurl and peel in milliseconds. Their toes have up to 15,000 hairs per foot, and each hair has “an awful case of split ends, with as many as a thousand nano-sized tips that allow close surface contact,” he said.
These discoveries have spawned research on new types of adhesives that use intermolecular forces, or van der Waals forces, to stick almost anywhere, even underwater.
One puzzle, he said, is that gecko toes only stick in one direction. They grab when pulled in one direction, but release when peeled in the opposite direction. Yet, geckos move agilely in any orientation.
To determine how geckos have learned to deal with shifting forces as they move on different surfaces, Yi Song, a UC Berkeley visiting student from Nanjing, China, ran geckos sideways along a vertical wall while making high-speed video recordings to show the orientation of their toes. The sideways movement allowed him to distinguish downward gravity from forward running forces to best test the idea of toe compensation.
Using a technique called frustrated total internal reflection, Song, also measured the area of contact of each toe. The technique made the toes light up when they touched a surface.
To the researcher’s surprise, geckos ran sideways just as fast as they climbed upward, easily and quickly realigning their toes against gravity. The toes of the front and hind top feet during sideways wall-running shifted upward and acted just like toes of the front feet during climbing.
To further explore the value of adjustable toes, researchers added slippery patches and strips, as well as irregular surfaces. To deal with these hazards, geckos took advantage of having multiple, soft toes. The redundancy allowed toes that still had contact with the surface to reorient and distribute the load, while the softness let them conform to rough surfaces.
“Toes allowed agile locomotion by distributing control among multiple, compliant, redundant structures that mitigate the risks of moving on challenging terrain,” Full said. “Distributed control shows how biological adhesion can be deployed more effectively and offers design ideas for new robot feet, novel grippers and unique manipulators.”
The team, which also includes Zhendong Dai and Zhouyi Wang of the College of Mechanical and Electrical Engineering at Nanjing University of Aeronautics and Astronautics, published its findings this week in the journal Proceedings of the Royal Society B.
This study comes from China and it offers an overview of the state-of-the-art of gas nanomedicine and a roadmap for future research. A May 6, 2020 news item on Nanowerk announces the study,
Cancer is deadly, but available cancer treatment methods are quite limited. The use of therapeutic gas molecules such as H2 [hydrogen gas], NO [nitrogen oxide], CO [carbon monoxide] and H2S [hydrogn sulfide] for cancer treatment is promising owing to their unique properties for selectively killing cancer cells and protecting normal cells from damage from other traditional therapies.
However, these gases and most of their prodrugs lack the abilities of active intratumoral accumulation and controlled gas release, causing limited therapeutic efficacy and potential side effects. The development of precision and intelligent gas delivery nanomedicines can maximize the profits of gas therapy by enhancing the bio-availability and bio-safety of therapeutic gases.
More and more gas-releasing nanomedicines are being developed by virtue of multifunctional nanoplatforms, making it ever-increasingly expectable to make breakthrough in cancer treatment. Even so, there are still many gaps between gas therapy and nanomedicines, needing to be filled.
In a new overview published in the Beijing-based National Science Review, scientists at Shenzhen University, China propose a series of engineering strategies of advanced gas-releasing nanomedicines for augmented cancer therapy from four aspects, 1) stimuli-responsive strategies for controlled gas release, 2) catalytic strategies for controlled gas release, 3) tumor-targeted gas delivery strategies, 4) multi-model combination strategies based on gas therapy.
A May 6, 2020 China Science Press news release on EurekAlert, which originated the news item, provides a little more detail about the overview and about a future application as an assistive therapy in diseases such as coronovirus pneumonia,
“This review systematically dissects the roles of carrier and gas prodrug within nanomedicine for stimuli-responsive gas release, catalytic gas generation routes, tumor-targeted gas delivery approaches and gas therapy-based combination methods, and also provides an insight into their engineering principles and working mechanisms, and correspondingly proposed a series of superior engineering strategies of nanomedicines for gas therapy of cancer to guide the future research.” Dr. Yingshuai Wang said “We believe this review could provide inspiration for constructing advanced gas-releasing nanomedicines.”
Moreover, they have also pointed out current issues and gaps in knowledge, and have envisaged current trends and future prospects of advanced nanomedicines for gas therapy of cancer in this review.
“There are many gaps intriguing me, such as high tissue penetration stimuli-responsive gas release, the local, endless and prodrug-free generation of gases by catalysis, and the super ability of assisting other almost all therapies.” Prof. Qianjun He adds “It is noticeable, in the recent fight of novel coronavirus pneumonia, hydrogen therapy is playing an vitally important role in assisting large numbers of patients to improve oxygen inhalation, relieve hypoxia, and scavenge inflammation. I hope our hydrogen-producing medicines would make bigger contribution to human being in the near future.”
This appears to be an open access paper in PDF only.
For anyone new to the term, a prodrug is (Note: Links have been removed),
A prodrug is a medication or compound that, after administration, is metabolized (i.e., converted within the body) into a pharmacologically active drug.Inactive prodrugs are pharmacologically inactive medications that are metabolized into an active form within the body. Instead of administering a drug directly, a corresponding prodrug might be used instead to improve how a medicine is absorbed, distributed, metabolized, and excreted (ADME).
Last week (specifically, Tuesday, March 3, 2020), someone moved away from me during a class. I’d sneezed.
The irony of the situation is that of the two of us, with my lung issues I’d be the one most at risk of getting very ill and/or dying from COVID-19. ( Yes, I confirmed that was the reason she’d moved.  The therapeutic nanoparticles news item is coming later) Here are the risk factors to take into account (from the US Centers for Disease Control’s People at Risk for Serious Illness from COVID-19 webpage,
Older adults [Note: In one report the age range was stated as ‘people over 70’]
People who have serious chronic medical conditions like:
I’m not suggesting that all precautions be abandoned but it would seem that panic might not be called for. Jeremy Samuel Faust, an emergency medicine physician at Brigham and Women’s Hospital in Boston, faculty in its division of health policy and public health, and an instructor at Harvard Medical School, has written a calming March 4, 2020 article (COVID-19 Isn’t As Deadly As We Think; Don’t hoard masks and food. Figure out how to help seniors and the immunosuppressed stay healthy.) for Slate.com (Note: Links have been removed],
There are many compelling reasons to conclude that SARS-CoV-2, the virus that causes COVID-19, is not nearly as deadly as is currently feared. But COVID-19 panic has set in nonetheless. You can’t find hand sanitizer in stores, and N95 face masks are being sold online for exorbitant prices, never mind that neither is the best way to protect against the virus (yes, just wash your hands). The public is behaving as if this epidemic is the next Spanish flu, which is frankly understandable given that initial reports have staked COVID-19 mortality at about 2–3 percent, quite similar to the 1918 pandemic that killed tens of millions of people.
Allow me to be the bearer of good news. These frightening numbers are unlikely to hold. The true case fatality rate, known as CFR, of this virus is likely to be far lower than current reports suggest. Even some lower estimates, such as the 1 percent death rate recently mentioned by the directors of the National Institutes of Health and the Centers for Disease Control and Prevention, likely substantially overstate the case. [emphases mine]
But the most straightforward and compelling evidence that the true case fatality rate of SARS-CoV-2 is well under 1 percent comes not from statistical trends and methodological massage, but from data from the Diamond Princess cruise outbreak and subsequent quarantine off the coast of Japan.
A quarantined boat is an ideal—if unfortunate—natural laboratory to study a virus. Many variables normally impossible to control are controlled. We know that all but one patient boarded the boat without the virus. We know that the other passengers were healthy enough to travel. We know their whereabouts and exposures. While the numbers coming out of China are scary, we don’t know how many of those patients were already ill for other reasons. How many were already hospitalized for another life-threatening illness and then caught the virus? How many were completely healthy, caught the virus, and developed a critical illness? In the real world, we just don’t know.
Here’s the problem with looking at mortality numbers in a general setting: In China, 9 million people die per year, which comes out to 25,000 people every single day, or around 1.5 million people over the past two months alone. A significant fraction of these deaths results from diseases like emphysema/COPD, lower respiratory infections, and cancers of the lung and airway whose symptoms are clinically indistinguishable from the nonspecific symptoms seen in severe COVID-19 cases. And, perhaps unsurprisingly, the death rate from COVID-19 in China spiked precisely among the same age groups in which these chronic diseases first become common. During the peak of the outbreak in China in January and early February, around 25 patients per day were dying with SARS-CoV-2. Most were older patients in whom the chronic diseases listed above are prevalent. Most deaths occurred in Hubei province, an area in which lung cancer and emphysema/COPD are significantly higher than national averages in China, a country where half of all men smoke. How were doctors supposed to sort out which of those 25 out of 25,000 daily deaths were solely due to coronavirus, and which were more complicated? What we need to know is how many excess deaths this virus causes.
This all suggests that COVID-19 is a relatively benign disease for most young people, and a potentially devastating one for the old and chronically ill, albeit not nearly as risky as reported. Given the low mortality rate among younger patients with coronavirus—zero in children 10 or younger among hundreds of cases in China, and 0.2-0.4 percent in most healthy nongeriatric adults (and this is still before accounting for what is likely to be a high number of undetected asymptomatic cases)—we need to divert our focus away from worrying about preventing systemic spread among healthy people—which is likely either inevitable, or out of our control—and commit most if not all of our resources toward protecting those truly at risk of developing critical illness and even death: everyone over 70, and people who are already at higher risk from this kind of virus.
This still largely comes down to hygiene and isolation. But in particular, we need to focus on the right people and the right places. Nursing homes, not schools. Hospitals, not planes. We need to up the hygienic and isolation ante primarily around the subset of people who can’t simply contract SARS-CoV-2 and ride it out the way healthy people should be able to.
Curtis Kim of Vancouver, Canada, has created a website dedicated to tracking the statistics and information about COVID-19 in Canada and around the world. Here’s more about Kim and the website from a March 8, 2020 article by Megan Devlin for the Daily Hive,
Curtis Kim, who studied Computer Systems Technology at the British Columbia Institute of Technology [BCIT], launched the site this week after getting frustrated he was spending so much time on various websites looking for daily coronavirus updates.
The site breaks down the number of cases in Canada, the number of deaths (zero in Canada so far), and the number of people who have recovered. Further down, it provides the same stats for global COVID-19 cases.
There’s also a colour-coded map showing where cases are distributed, and a feed of latest news articles about the virus. Kim also included information about symptoms and how to contact Canadian public health services.
Kim is looking for work and given what I’ve seen of his COVID-19 website, he should have no difficulty. Although I think it might be an idea for him to explain how the ‘lethality’ rate on his website has been obtained since Faust who seems to have more directly relevant experience suggests in his article that the numbers are highly problematic,
My name is Curtis, recently graduated from BCIT. I thought it would be a serious worldwide issue considering the speed of the spread of this virus ever since this COVID-19 occurred. I frequently googled to check up the current status by going through many websites and felt I was wasting time repeatedly searching with same keywords and for sure I wasn’t the only one feeling this way. That’s why I started creating this application. It provides up-to-date information on the COVID-19 broken by province and country around the world, key contact information, and latest news. I like to help people, and want them to understand this situation easily using this application. Hopefully this situation improves soon.
If you have any further inquries about the information on this web application, Please reach me at email@example.com
At about 11:45 am (PT) on March 9, 2020, Kim’s COVID-19 website was updated to include one death in Canada. As you might expect, ti was a resident in a long term care home. Wanyee Li’s March 9, 2020 article for The Star presents the news,
A resident at a long-term care home experiencing a COVID-19 outbreak in North Vancouver has died after contracting the virus, B.C. health officials confirmed Monday [March 9, 2020].
It is the first reported death in Canada linked to the virus.
The outbreak at the Lynn Valley Care Centre has so far been linked to three community transmission cases of the virus.
Provincial Health Officer Dr. Bonnie Henry confirmed five new cases of COVID-19 in B.C. on Monday [March 9, 2020], putting the total in the province at 32.
The five new cases include one health-care worker, two people who are close contacts of an existing case, one person who recently returned from travel to Iran and another who was in Italy recently.
Officials are conducting an investigation into the three community transmission cases at the long-term care home to determine how a health care worker contracted the virus.
I looked up the population figures for the province of British Columbia (BC; Wikipedia entry for Demographics of British Columbia). As of the 2016 census, there were 4,648,055 people in the province. Assuming that population number holds, 67 cases in all of Canada (with 27 cases in BC) of COVID-19 don’t seem like big numbers.
We should definitely take precautions and be careful but there’s no need to panic.
There is no vaccine or specific treatment for COVID-19, the disease caused by the severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2.
Since the outbreak began in late 2019, researchers have been racing to learn more about SARS-CoV-2, which is a strain from a family of viruses known as coronavirus for their crown-like shape.
Northeastern Ûniversity] chemical engineer Thomas Webster, who specializes in developing nano-scale medicine and technology to treat diseases, is part of a contingency of scientists that are contributing ideas and technology to the Centers for Disease Control and Prevention to fight the COVID-19 outbreak.
The idea of using nanoparticles, Webster says, is that the virus behind COVID-19 consists of a structure of a similar scale as his nanoparticles. At that scale, matter is ultra-small, about ten thousand times smaller than the width of a single strand of hair.
Webster is proposing particles of similar sizes that could attach to SARS-CoV-2 viruses, disrupting their structure with a combination of infrared light treatment. That structural change would then halt the ability of the virus to survive and reproduce in the body.
“You have to think in this size range,” says Webster, Art Zafiropoulo Chair of chemical engineering at Northeastern. “In the nanoscale size range, if you want to detect viruses, if you want to deactivate them.”
Finding and neutralizing viruses with nanomedicine is at the core of what Webster and other researchers call theranostics, which focuses on combining therapy and diagnosis. Using that approach, his lab has specialized in nanoparticles to fight the microbes that cause influenza and tuberculosis.
“It’s not just having one approach to detect whether you have a virus and another approach to use it as a therapy,” he says, “but having the same particle, the same approach, for both your detection and therapy.”
I wish Webster good luck. As for the rest us, let’s wash our hands and keep calm.
I may be mistaken but the implication seems to be that Charles M. Lieber’s lies (he was charged today, January 28, 2020 ) are the ‘tip of the iceberg’ of a very large problem. Ellen Barry’s January 28, 2020 article for the New York Times outlines at least part of what the US government is doing to discover and ultimately discourage the theft of biomedical research from US laboratories.
Dr. Lieber, a leader in the field of nanoscale electronics, was one of three Boston-area scientists accused on Tuesday [January 28, 2020] of working on behalf of China. His case involves work with the Thousand Talents Program, a state-run program that seeks to draw talent educated in other countries.
American officials are investigating hundreds of cases of suspected theft of intellectual property by visiting scientists, nearly all of them Chinese nationals or of Chinese descent. Some are accused of obtaining patents in China based on work that is funded by the United States government, and others of setting up laboratories in China that secretly duplicated American research.
Dr. Lieber, who was arrested on Tuesday [January 28, 2020], stands out among the accused scientists, because he is neither Chinese nor of Chinese descent. …
Lieber is the Chair of Harvard’s Department of Chemistry and Chemical Biology and much more, according to his Wikipedia entry (Note: Links have been removed),
Charles M. Lieber (born 1959) is an American chemist and pioneer in the field of nanoscience and nanotechnology. In 2011, Lieber was recognized by Thomson Reuters as the leading chemist in the world for the decade 2000-2010 based on the impact of his scientific publications. Lieber has published over 400 papers in peer-reviewed scientific journals and has edited and contributed to many books on nanoscience. He is the principal inventor on over fifty issued US patents and applications, and founded the nanotechnology company Nanosys in 2001 and Vista Therapeutics in 2007. He is known for his contributions to the synthesis, assembly and characterization of nanoscale materials and nanodevices, the application of nanoelectronic devices in biology, and as a mentor to numerous leaders in nanoscience. Thompson Reuters predicted Lieber to be a recipient of the 2008 Nobel Prize in Chemistry [to date, January 28, 2020, Lieber has not received a Nobel prize].
Should you search Charles Lieber or Charles M. Lieber on this blog’s search engine, you will find a number of postings about his and his students’ work dating from 2012 to as recently as November 15, 2019.
Here’s another example from Barry’s January 28, 2020 article for the New York Times which illustrates just how shocking this is (Note: Links have been removed),
In 2017 he was named a University Professor, Harvard’s highest faculty rank, one of only 26 professors to hold that status. The same year, he earned the National Institutes of Health Director’s Pioneer Award for inventing syringe-injectable mesh electronics that can integrate with the brain.
Harvard’s president at the time, Drew G. Faust, called him “an extraordinary scientist whose work has transformed nanoscience and nanotechnology and has led to a remarkable range of valuable applications that improve the quality of people’s lives.”
Here’s a bit more about the Chinese program that Lieber is affiliated with,
Launched in 2008, its [China] Thousand Talents Program is an effort to recruit Chinese and foreign academics and entrepreneurs. According to a report in the China Daily, new recruits receive 1 million yuan, or about $146,000, from the central government, and a pledge of 10 million yuan for their ongoing research from the Chinese Academy of Sciences.
The recruitment flows both ways. Researchers of Chinese descent make up nearly half of the work force in American research laboratories, in part because American-born scientists are drawn to the private sector and less interested in academic careers.
I encourage you to read Barry’s entire article. It is jaw-dropping and, where Lieber is concerned, sad. It’s beginning to look like US universities are corrupt. The Jeffrey Epstein (a wealthy and convicted sexual predator and more) connection to the Massachusetts Institute of Technology, which led to the resignation of a prominent faculty member (Sept. 19, 2019 article by Anna North for Vox.com), and the Fall 2019 cheating scandal (gaining admission to big name educational institutions by paying someone other than the student to take exams, among many other schemes) suggest a reckoning might be in order.
ETA January 28, 2020 at 1645 hours: I found a January 28, 2020 article by Antonio Regalado for the MIT Technology Review which provides a few more details about Lieber’s situation,
Big money: According to the charging document, Lieber, starting in 2011, agreed to help set up a research lab at the Wuhan University of Technology and “make strategic visionary and creative research proposals” so that China could do cutting-edge science.
He was well paid for it. Lieber earned a salary when he visited China worth up to $50,000 per month, as well as $150,000 a year in expenses in addition to research funds. According to the complaint, he got paid by way of a Chinese bank account but also was known to send emails asking for cash instead.
Harvard eventually wised up to the existence of a Wuhan lab using its name and logo, but when administrators confronted Lieber, he lied and said he didn’t know about a formal joint program, according to the government complaint.
I imagine the money paid by the Chinese government is in addition to Lieber’s Harvard salary (no doubt a substantial one especially since he’s chair of his department and one of a select number of Harvard’s University Professors) and in addition to any other deals he might have on the side.
An August 2, 2019 news item on ScienceDaily features some new work on wearable technology that was a bit of a surprise to me,
Wearable human-machine interfaces — devices that can collect and store important health information about the wearer, among other uses — have benefited from advances in electronics, materials and mechanical designs. But current models still can be bulky and uncomfortable, and they can’t always handle multiple functions at one time.
Researchers reported Friday, Aug. 2 , the discovery of a multifunctional ultra-thin wearable electronic device that is imperceptible to the wearer.
I expected this wearable technology to be a piece of clothing that somehow captured health data but it’s not,
The device allows the wearer to move naturally and is less noticeable than wearing a Band-Aid, said Cunjiang Yu, Bill D. Cook Associate Professor of Mechanical Engineering at the University of Houston and lead author for the paper, published as the cover story in Science Advances.
“Everything is very thin, just a few microns thick,” said Yu, who also is a principal investigator at the Texas Center for Superconductivity at UH. “You will not be able to feel it.” It has the potential to work as a prosthetic skin for a robotic hand or other robotic devices, with a robust human-machine interface that allows it to automatically collect information and relay it back to the wearer.
That has applications for health care – “What if when you shook hands with a robotic hand, it was able to instantly deduce physical condition?” Yu asked – as well as for situations such as chemical spills, which are risky for humans but require human decision-making based on physical inspection.
While current devices are gaining in popularity, the researchers said they can be bulky to wear, offer slow response times and suffer a drop in performance over time. More flexible versions are unable to provide multiple functions at once – sensing, switching, stimulation and data storage, for example – and are generally expensive and complicated to manufacture.
The device described in the paper, a metal oxide semiconductor on a polymer base, offers manufacturing advantages and can be processed at temperatures lower than 300 C.
“We report an ultrathin, mechanically imperceptible, and stretchable (human-machine interface) HMI device, which is worn on human skin to capture multiple physical data and also on a robot to offer intelligent feedback, forming a closed-loop HMI,” the researchers wrote. “The multifunctional soft stretchy HMI device is based on a one-step formed, sol-gel-on-polymer-processed indium zinc oxide semiconductor nanomembrane electronics.”
In addition to Yu, the paper’s co-authors include first author Kyoseung Sim, Zhoulyu Rao, Faheem Ershad, Jianming Lei, Anish Thukral and Jie Chen, all of UH; Zhanan Zou and Jianliang Xiao, both of the University of Colorado; and Qing-An Huang of Southeast University in Nanjing, China.
I’m fascinated by the image. Are they suggesting putting implants into people’s brains that can sense dangerous gaseous molecules and convert that into data which can be read on a smartphone? And, are they harvesting bioenergy to supply energy to the implant?
A July 29, 2019 news item on Azonano was not as helpful in answering my questions as I’d hoped (Note: A link has been removed),
An artificial olfactory system based on a self-powered nano-generator has been built by Prof. ZHAN Yang’s team at the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences [CAS], together with colleagues at the University of Electronic Science and Technology of China.
The device, which can detect a variety of odor molecules and identify different odors, has been demonstrated in vivo in animal models. The research titled “An artificial triboelectricity-brain-behavior closed loop for intelligent olfactory substitution” has been reported in Nano Energy.
Odor processing is important to many species. Specific olfactory receptors located on the neurons are involved in odor recognition. These different olfactory receptors form patterned distribution.
Inspired by the biological receptors, the teams collaborated on formulating an artificial olfactory system. Through nano-fabrication on the soft materials and special alignment of material structures, the teams built a self-power device that can code and differentiate different odorant molecules.
This device has been connected to the mouse brain to demonstrate that the olfactory signals can produce appropriate neural stimulation. When the self-powered device generated the electric currents, the mouse displayed behavioral motion changes.
This study, inspired by the biological olfactory system, provides insights on novel design of neural stimulation and brain-machine interface.
A new software system developed by Brown University [US] researchers turns cell phones into augmented reality portals, enabling users to place virtual building blocks, furniture and other objects into real-world backdrops, and use their hands to manipulate those objects as if they were really there.
The developers hope the new system, called Portal-ble, could be a tool for artists, designers, game developers and others to experiment with augmented reality (AR). The team will present the work later this month at the ACM Symposium on User Interface Software and Technology (UIST 2019) in New Orleans. The source code for Andriod is freely available for download on the researchers’ website, and iPhone code will follow soon.
“AR is going to be a great new mode of interaction,” said Jeff Huang, an assistant professor of computer science at Brown who developed the system with his students. “We wanted to make something that made AR portable so that people could use anywhere without any bulky headsets. We also wanted people to be able to interact with the virtual world in a natural way using their hands.”
Huang said the idea for Portal-ble’s “hands-on” interaction grew out of some frustration with AR apps like Pokemon GO. AR apps use smartphones to place virtual objects (like Pokemon characters) into real-world scenes, but interacting with those objects requires users to swipe on the screen.
“Swiping just wasn’t a satisfying way of interacting,” Huang said. “In the real world, we interact with objects with our hands. We turn doorknobs, pick things up and throw things. So we thought manipulating virtual objects by hand would be much more powerful than swiping. That’s what’s different about Portal-ble.”
The platform makes use of a small infrared sensor mounted on the back of a phone. The sensor tracks the position of people’s hands in relation to virtual objects, enabling users to pick objects up, turn them, stack them or drop them. It also lets people use their hands to virtually “paint” onto real-world backdrops. As a demonstration, Huang and his students used the system to paint a virtual garden into a green space on Brown’s College Hill campus.
Huang says the main technical contribution of the work was developing the right accommodations and feedback tools to enable people to interact intuitively with virtual objects.
“It turns out that picking up a virtual object is really hard if you try to apply real-world physics,” Huang said. “People try to grab in the wrong place, or they put their fingers through the objects. So we had to observe how people tried to interact with these objects and then make our system able accommodate those tendencies.”
To do that, Huang enlisted students in a class he was teaching to come up with tasks they might want to do in the AR world — stacking a set of blocks, for example. The students then asked other people to try performing those tasks using Portal-ble, while recording what people were able to do and what they couldn’t. They could then adjust the system’s physics and user interface to make interactions more successful.
“It’s a little like what happens when people draw lines in Photoshop,” Huang said. “The lines people draw are never perfect, but the program can smooth them out and make them perfectly straight. Those were the kinds of accommodations we were trying to make with these virtual objects.”
The team also added sensory feedback — visual highlights on objects and phone vibrations — to make interactions easier. Huang said he was somewhat surprised that phone vibrations helped users to interact. Users feel the vibrations in the hand they’re using to hold the phone, not in the hand that’s actually grabbing for the virtual object. Still, Huang said, vibration feedback still helped users to more successfully interact with objects.
In follow-up studies, users reported that the accommodations and feedback used by the system made tasks significantly easier, less time-consuming and more satisfying.
Huang and his students plan to continue working with Portal-ble — expanding its object library, refining interactions and developing new activities. They also hope to streamline the system to make it run entirely on a phone. Currently the infrared sensor requires an infrared sensor and external compute stick for extra processing power.
Huang hopes people will download the freely available source code and try it for themselves. “We really just want to put this out there and see what people do with it,” he said. “The code is on our website for people to download, edit and build off of. It will be interesting to see what people do with it.
Co-authors on the research paper were Jing Qian, Jiaju Ma, Xiangyu Li, Benjamin Attal, Haoming Lai, James Tompkin and John Hughes. The work was supported by the National Science Foundation (IIS-1552663) and by a gift from Pixar.
This is the first time I’ve seen an augmented reality system that seems accessible, i.e., affordable. You can find out more on the Portal-ble ‘resource’ page where you’ll also find a link to the source code repository. The researchers, as noted in the news release, have an Android version available now with an iPhone version to be released in the future.
Xuan paper is special being both rare and used for calligraphy and art works. Before getting to the ‘fire-resistant’ news, it might be helpful to get some details about Xuan paper as it is typically prepared and used (from a Dec. 29, 2018 news item on xinhuanet.com),
Today’s Chinese artists now have the opportunity to preserve their works much longer than the masters who painted hundreds of years ago.
Chinese researchers have developed a non-flammable version of Xuan paper that has high thermal stability, according to the Chinese Academy of Sciences (CAS).
Xuan paper, a type of handmade paper, was originally produced in ancient China and used for both Chinese calligraphy and paintings. The procedure of making Xuan paper was listed as a world intangible cultural heritage by UNESCO in 2009.
The raw materials need to produce Xuan paper are found in Jingxian County, east China’s Anhui Province and as of late, are in short supply.
The traditional handmade method of Xuan paper involves more than 100 steps and takes nearly two years [emphasis mine]. It has a low output and high cost. Xuan paper made with organic materials often suffers from degradation, yellowing and deteriorating properties during the long-term natural aging process.
Furthermore, the most lethal problem of traditional Xuan paper is its high flammability.
A January 18, 2019 news item on Nanowerk adds a few more details about the traditional paper while describing the ‘new’ Xuan paper (Note: A link has been removed),
Xuan paper is an excellent example of the traditional handmade paper, and features excellent properties of durability, ink wetting, and resistance to insects and mildew. Its excellent durability is attributed to its unique raw materials and handmade manufacturing process under mild conditions.
The bark of pteroceltis tatarinowii, a common species of elm in the area, is used as the main raw material to produce Xuan paper. Limestone particles are deposited on the surface of pteroceltis bark fibers, which can neutralize acids produced by the hydrolysis of plant fibers and from the environment.
Since the raw materials are only produced in Jing County, Anhui Province, China, Xuan paper suffers from a severe shortage. Also, it has the shortcomings such as complicated traditional hand making process and flammability. In a recent paper published in ACS Sustainable Chemistry & Engineering (“Fire-Resistant Inorganic Analogous Xuan Paper with Thousands of Years’ Super-Durability”), a team led by Prof. ZHU Yingjie from Shanghai Institute of Ceramics of Chinese Academy of Sciences developed a new kind of “fire-resistant Xuan paper” based on ultralong hydroxyapatite nanowires.
The unique integral structure of the “fire-resistant Xuan paper” with excellent mechanical properties and high flexibility was designed to be similar to the reinforced concrete structure in tall buildings. Ultralong hydroxyapatite nanowires are used as the main building material and are similar to the concrete. Silica glass fibers with micrometer-sized diameters are used as the reinforcing framework material and are similar to supporting steel bars. In addition, a new kind of inorganic adhesive composed of amorphous nanoparticles was designed, prepared and used as the binder in the “fire-resistant Xuan paper”.
The as-prepared “fire-resistant Xuan paper” well keeps its properties even after the simulated aging for up to 3000 years.
The original whiteness of the “fire-resistant Xuan paper” is 92%, and its whiteness has a slight decrease to 91.6%, with the whiteness retention as high as 99.6% after the simulated aging for 2000 years. Even after the simulated aging for 3000 years, its whiteness only decreases to 86.7% with 94.2% of the whiteness retention. It is much higher than that of the traditional Xuan paper. The whiteness of the traditional unprocessed Xuan paper decreases from initial 70.5% to 47.3% with 67.1% of the whiteness retention after the simulated aging for 2000 years. Its whiteness decreases to 42.2% with 59.9% of the whiteness retention after the simulated aging for 3000 years.
The “fire-resistant Xuan paper” exhibits superior mechanical properties during the simulated aging process.
The retention percentage of tensile strength of the “fire-resistant Xuan paper” is as high as 95.2% aging for 2000 years, and 81.3% aging for 3000 years. In contrast, the average retention percentage of tensile strength of the unprocessed Xuan paper is only 54.9% aging for 2000 years, and 40.4% aging for 3000 years. Furthermore, the “fire-resistant Xuan paper” has an excellent ink wetting performance, which is mainly attributed to the nanoscale porous structure and hydroxyl groups of utralong hydroxyapatite nanowires.
The prevention of mould growth on the paper is a great challenge, because the mould can cause the deterioration of the Xuan paper. In this study, experiments showed that different kinds of mould spores do not breed and spread on the “fire-resistant Xuan paper”, and it is able to maintain a clean surface without the growth of any mould, indicating the excellent anti-mildew performance of the “fire-resistant Xuan paper” even exposure to the external nutrients. On the contrary, the growth and spread of mould are obviously observed on the traditional Xuan paper in the presence of external nutrients, indicating that its anti-mildew performance is not satisfactory.
The most important property is that the “fire-resistant Xuan paper” is fire resistant and highly thermal stable. Thus it can prevent the precious calligraphy and painting works as well as books, documents, and archives from the damage by fire. In addition, the production process of the “fire-resistant Xuan paper” is simple, highly efficient, and it only needs 3~4 days to produce.
Xuan paper is the best material carrier for the calligraphy and painting arts, many of which have been well preserved for hundreds of years.