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This 3D printer doesn’t gloss over the details

A new system enables realistic variations in glossiness across a 3D-printed surface; the advance could aid fine art reproduction and

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A new system enables realistic variations in glossiness across a 3D-printed surface; the advance could aid fine art reproduction and the design of prosthetics

Shape, color, and gloss.

Those are an object’s three most salient visual features. Currently, 3D printers can reproduce shape and color reasonably well. Gloss, however, remains a challenge. That’s because 3D printing hardware isn’t designed to deal with the different viscosities of the varnishes that lend surfaces a glossy or matte look.

MIT researcher Michael Foshey and his colleagues may have a solution. They’ve developed a combined hardware and software printing system that uses off-the-shelf varnishes to finish objects with realistic, spatially varying gloss patterns. Foshey calls the advance “a chapter in the book of how to do high-fidelity appearance reproduction using a 3D printer.”

He envisions a range of applications for the technology. It might be used to faithfully reproduce fine art, allowing near-flawless replicas to be distributed to museums without access to originals. It might also help create more realistic-looking prosthetics. Foshey hopes the advance represents a step toward visually perfect 3D printing, “where you could almost not tell the difference between the object and the reproduction.”

Foshey, a mechanical engineer in the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL), will present the paper at next month’s SIGGRAPH Asia conference, along with lead author Michal Piovarči of the University of Lugano in Switzerland. Co-authors include MIT’s Wojciech Matusik, Vahid Babaei of the Max Planck Institute, Szymon Rusinkiewicz of Princeton University, and Piotr Didyk of the University of Lugano.

Glossiness is simply a measure of how much light is reflected from a surface. A high gloss surface is reflective, like a mirror. A low gloss, or matte, surface is unreflective, like concrete. Varnishes that lend a glossy finish tend to be less viscous and to dry into a smooth surface. Varnishes that lend a matte finish are more viscous — closer to honey than water. They contain large polymers that, when dried, protrude randomly from the surface and absorb light. “You have a bunch of these particles popping out of the surface, which gives you that roughness,” says Foshey.

But those polymers pose a dilemma for 3D printers, whose skinny fluid channels and nozzles aren’t built for honey. “They’re very small, and they can get clogged easily,” says Foshey.

The state-of-the-art way to reproduce a surface with spatially varying gloss is labor-intensive: The object is initially printed with high gloss and with support structures covering the spots where a matte finish is ultimately desired. Then the support material is removed to lend roughness to the final surface. “There’s no way of instructing the printer to produce a matte finish in one area, or a glossy finish in another,” says Foshey. So, his team devised one.

They designed a printer with large nozzles and the ability to deposit varnish droplets of varying sizes. The varnish is stored in the printer’s pressurized reservoir, and a needle valve opens and closes to release varnish droplets onto the printing surface. A variety of droplet sizes is achieved by controlling factors like the reservoir pressure and the speed of the needle valve’s movements. The more varnish released, the larger the droplet deposited. The same goes for the speed of the droplet’s release. “The faster it goes, the more it spreads out once it impacts the surface,” says Foshey. “So we essentially vary all these parameters to get the droplet size we want.”

The printer achieves spatially varying gloss through halftoning. In this technique, discrete varnish droplets are arranged in patterns that, when viewed from a distance, appear like a continuous surface. “Our eyes actually do the mixing itself,” says Foshey. The printer uses just three off-the-shelf varnishes — one glossy, one matte, and one in between. By incorporating these varnishes into its preprogrammed halftoning pattern, the printer can yield continuous, spatially varying shades of glossiness across the printing surface.

Along with the hardware, Foshey’s team produced a software pipeline to control the printer’s output. First, the user indicates their desired gloss pattern on the surface to be printed. Next, the printer runs a calibration, trying various halftoning patterns of the three supplied varnishes. Based on the reflectance of those calibration patterns, the printer determines the proper halftoning pattern to use on the final print job to achieve the best possible reproduction. The researchers demonstrated their results on a variety of “2.5D” objects — mostly-flat printouts with textures that varied by half a centimeter in height. “They were impressive,” says Foshey. “They definitely have more of a feel of what you’re actually trying to reproduce.”

The team plans to continue developing the hardware for use on fully-3D objects. Didyk says “the system is designed in such a way that the future integration with commercial 3D printers is possible.”

This work was supported by the National Science Foundation and the European Research council.

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Written by Daniel Ackerman, MIT News Office

Additional background

Paper: “Towards Spatially Varying Gloss Reproduction for 3D Printing”
https://gfx.cs.princeton.edu/pubs/Piovar%C4%8Di_2020_TSV/glossprint_sga20.pdf

Source: https://bioengineer.org/this-3d-printer-doesnt-gloss-over-the-details/

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Bioengineer

$1 million grant to address cold storage logistics in vaccine delivery

Credit: Penn State College of Engineering COVID-19 vaccines have been tested, validated and administered to millions of people around the

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COVID-19 vaccines have been tested, validated and administered to millions of people around the world. But in some countries, the vaccines have yet to arrive in great enough numbers.

One significant hurdle is that the vaccines must be stored between 36 and 46 degrees Fahrenheit to retain their full efficacy, according to the Centers for Disease Control. To ensure the proper temperature, the vaccines need a refrigerated supply chain, also known as a cold chain, as they are distributed across the globe.

“If they are in warm temperatures, COVID vaccines and other medications are susceptible to degradation, which means they lose potency,” said Medina, who heads the Medina Group Precision Therapeutics and Bioresponsive Materials Lab at Penn State. “And the cold storage supply chain is expensive to maintain, with several transport steps necessary from the manufacturer to the distributer to the provider facility.”

To address that challenge, Medina and his team plan to develop fluorochemical dispersants, known as “FTags,” which coat the proteins within the vaccine liquids to stabilize them thermally.

“The FTags dissolve the proteins in a fluorine-based liquid, which yields proteins that we believe may be stable at elevated temperatures, without compromising their structure or function,” Medina said. “When dissolved in the fluorine-based liquid, the proteins also are immune to contamination by microorganisms and enzymes.”

Fluorochemicals are used in a range of applications, such as in making surfaces resistant to scratches and chemical degradation, as in the case of non-stick cookware.

Eventually, Medina plans to study the use of fluorochemical coatings in other biological products, with the goal of eliminating the need to move any pharmaceutical via a cold chain.

“This will allow access to medications in places where currently there is not,” Medina said. “For example, a soldier at war could be exposed to a harmful chemical agent. A fluorochemical-coated protein, which can be carried without refrigeration, could neutralize that agent immediately. This is part of DARPA’s interest in supplying this grant.”

The grant is part of DARPA’s Young Faculty Award program, which provides funding, mentoring and networking opportunities to faculty early in their careers who plan to focus their research on Department of Defense and national security interests.

In 2020, Medina published a study in ACS Nano on delivering therapeutic medications directly to a precise area of the body through an acoustically sensitive carrier, guided by ultrasound. The proposed DARPA-funded study is a spin-off of that study’s findings.

“Janna Sloand, my former grad student who recently defended her doctoral research, came up with the coating technology in our last study,” Medina said. “It dovetails nicely with our new study, which will use those same coatings to take on the limitations of the cold chain.”

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Source: https://bioengineer.org/1-million-grant-to-address-cold-storage-logistics-in-vaccine-delivery/

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Reduced microbial stability linked to soil carbon loss in active layer under alpine permafrost degra

Credit: NIEER Chinese researchers have recently discovered links between reduction in microbial stability and soil carbon loss in the active

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Chinese researchers have recently discovered links between reduction in microbial stability and soil carbon loss in the active layer of degraded alpine permafrost on the Qinghai-Tibet Plateau (QTP).

The researchers, headed by Prof. CHEN Shengyun from the Northwest Institute of Eco-Environment and Resources (NIEER) of the Chinese Academy of Sciences (CAS), and XUE Kai from University of Chinese Academy of Sciences, conducted a combined in-depth analysis of soil microbial communities and their co-occurrence networks in the active permafrost layer along an extensive gradient of permafrost degradation.

The QTP encompasses the largest extent of high-altitude mountain permafrost in the world. This permafrost is different than high-latitude permafrost and stores massive soil carbon. An often ignored characteristic of permafrost is that the carbon pool in the active layer soil is more active and directly affected by climate change, compared to deeper layers.

Triggered by climate warming, permafrost degradation may decrease soil carbon stability and induce massive carbon loss, thus leading to positive carbon-climate feedback. However, microbial-mediated mechanisms for carbon loss from the active layer soil in degraded permafrost still remain unclear.

In this study, the researchers found that alpine permafrost degradation reduced the stability of active layer microbial communities as evidenced by increased sensitivity of microbial composition to environmental change, promoted destabilizing network properties and reduced resistance to node or edge attacking of the microbial network.

They discovered that soil organic carbon loss in severely degraded permafrost is associated with increased microbial dissimilarity, thereby potentially contributing to a positive carbon feedback in alpine permafrost on the QTP.

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The results were published in PNAS in an article entitled “Reduced microbial stability in the active layer is associated with carbon loss under alpine permafrost degradation”.

This research was financially supported by the National Natural Science Foundation of China, the Strategic Priority Research Program (A) of CAS and the Second Tibetan Plateau Scientific Expedition and Research Program.

Triggered by climate warming, permafrost degradation may decrease soil carbon stability and induce massive carbon loss, thus leading to positive carbon-climate feedback. However, microbial-mediated mechanisms for carbon loss from the active layer soil in degraded permafrost still remain unclear.

Source: https://bioengineer.org/reduced-microbial-stability-linked-to-soil-carbon-loss-in-active-layer-under-alpine-permafrost-degra/

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SNMMI Image of the Year: PET imaging measures cognitive impairment in COVID-19 patients

Credit: G Blazhenets et al., Department of Nuclear Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of

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Credit: G Blazhenets et al., Department of Nuclear Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg.

Reston, VA–The effects of COVID-19 on the brain can be accurately measured with positron emission tomography (PET), according to research presented at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2021 Annual Meeting. In the study, newly diagnosed COVID-19 patients, who required inpatient treatment and underwent PET brain scans, were found to have deficits in neuronal function and accompanying cognitive impairment, and in some, this impairment continued six months after their diagnosis. The detailed depiction of areas of cognitive impairment, neurological symptoms and comparison of impairment over a six-month time frame has been selected as SNMMI’s 2021 Image of the Year.

Each year, SNMMI chooses an image that best exemplifies the most promising advances in the field of nuclear medicine and molecular imaging. The state-of-the-art technologies captured in these images demonstrate the capacity to improve patient care by detecting disease, aiding diagnosis, improving clinical confidence, and providing a means of selecting appropriate treatments. This year, the SNMMI Henry N. Wagner, Jr., Image of the Year was chosen from more than 1,280 abstracts submitted to the meeting and voted on by reviewers and the society leadership.

“As the SARS-CoV-2 pandemic proceeds, it has become increasingly clear that neurocognitive long-term consequences occur not only in severe COVID-19 cases, but in mild and moderate cases as well. Neurocognitive deficits like impaired memory, disturbed concentration and cognitive problems may persist well beyond the acute phase of the disease,” said Ganna Blazhenets, PhD, a post-doctoral researcher in Medical Imaging at the University Medical Center Freiburg, in Freiburg, Germany.

To study cognitive impairment associated with COVID-19, researchers carried out a prospective study on recently diagnosed COVID-19 patients who required inpatient treatment for non-neurological complaints. A cognitive assessment was performed, followed by imaging with 18F-FDG PET if at least two new neurological symptoms were present. By comparing COVID-19 patients to controls, the Freiburg group established a COVID-19-related covariance pattern of brain metabolism with most prominent decreases in cortical regions. Across patients, the expression of this pattern showed a very high correlation with the patients’ cognitive performance.

Follow-up PET imaging was performed six months after the initial COVID-19 diagnosis. Imaging results showed a significant improvement in the neurocognitive deficits in most patients, accompanied by an almost complete normalization of the brain metabolism.

“We can clearly state that a significant recovery of regional neuronal function and cognition occurs for most COVID-19 patients based on the results of this study. However, it is important to recognize the evidence of longer-lasting deficits in neuronal function and accompanying cognitive deficits is still measurable in some patients six months after manifestation of disease,” noted Blazhenets. “As a result, post-COVID-19 patients with persistent cognitive complaints should be presented to a neurologist and possibly allocated to cognitive rehabilitation programs.”

“18F-FDG PET is an established biomarker of neuronal function and neuronal injury,” stated SNMMI’s Scientific Program Committee chair, Umar Mahmood, MD, PhD. “As shown the Image of the Year, it can be applied to unravel neuronal correlates of the cognitive decline in patients after COVID-19. Since 18F-FDG PET is widely available, it may therefore aid in the diagnostic work-up and follow-up in patients with persistent cognitive impairment after COVID-19.”

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Abstract 41. “Altered regional cerebral function and its association with cognitive impairment in COVID 19: A prospective FDG PET study.” Ganna Blazhenets, Johannes Thurow, Lars Frings and Philipp Meyer, Department of Nuclear Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Nils Schroeter, Tobias Bormann, Cornelius Weiller, Andrea Dressing and Jonas Hosp; Department of Neurology and Clinical Neuroscience, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and Dirk Wagner, Department of Internal Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

All 2021 SNMMI Annual Meeting abstracts can be found online at https://jnm.snmjournals.org/content/62/supplement_1.

About the Society of Nuclear Medicine and Molecular Imaging

The Society of Nuclear Medicine and Molecular Imaging (SNMMI) is an international scientific and medical organization dedicated to advancing nuclear medicine and molecular imaging, vital elements of precision medicine that allow diagnosis and treatment to be tailored to individual patients in order to achieve the best possible outcomes.

SNMMI’s members set the standard for molecular imaging and nuclear medicine practice by creating guidelines, sharing information through journals and meetings and leading advocacy on key issues that affect molecular imaging and therapy research and practice. For more information, visit http://www.snmmi.org.

“As the SARS-CoV-2 pandemic proceeds, it has become increasingly clear that neurocognitive long-term consequences occur not only in severe COVID-19 cases, but in mild and moderate cases as well. Neurocognitive deficits like impaired memory, disturbed concentration and cognitive problems may persist well beyond the acute phase of the disease,” said Ganna Blazhenets, PhD, a post-doctoral researcher in Medical Imaging at the University Medical Center Freiburg, in Freiburg, Germany.

Source: https://bioengineer.org/snmmi-image-of-the-year-pet-imaging-measures-cognitive-impairment-in-covid-19-patients/

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