Tag Archives: nanocellulose

3D printed nanocellulose for green architectural applications

It’s not happening next week but it is a promising step forward if you’re looking for nancellulose applications. From a February 7, 2024 news item on Nanowerk, Note: A link has been removed,

For the first time, a hydrogel material made of nanocellulose and algae has been tested as an alternative, greener architectural material. The study, from Chalmers University of Technology in Sweden and the Wallenberg Wood Science Center, shows how the abundant sustainable material can be 3D printed into a wide array of architectural components, using much less energy than conventional construction methods.

Caption: 3D printed nanocellulose upscaled for green architectural applications. Credit: Chalmers University of Technology | Emma Fry

A February 6, 2024 Chalmers University of Technology press release (also on EurekAlert but published February 7, 2024), which originated the news item,

The construction industry today consumes 50 percent of the world’s fossil resources, generates 40 percent of global waste and causes 39 percent of global carbon dioxide emissions. There is a growing line of research into biomaterials and their applications, in order to transition to a greener future in line with, for example, the European Green Deal.

Nanocellulose is not a new biomaterial, and its properties as a hydrogel are known within the field of biomedicine, where it can be 3D printed into scaffolds for tissue and cell growth, due to its biocompatibility and wetness. But it has never been dried and used as an architectural material before.

“For the first time we have explored an architectural application of nanocellulose hydrogel. Specifically, we provided the so far missing knowledge on its design-related features, and showcased, with the help of our samples and prototypes, the tuneability of these features through custom digital design and robotic 3D printing,” says Malgorzata Zboinska, lead author of the study from Chalmers University of Technology.

The team used nanocellulose fibres and water, with the addition of an algae-based material called alginate. The alginate allowed the researchers to produce a 3D printable material, since the alginate added an extra flexibility to the material when it dried.

Cellulose is coined as the most abundant eco-friendly alternative to plastic, as it is one of the byproducts of the world’s largest industries. “The nanocellulose used in this study can be acquired from forestry, agriculture, paper mills and straw residues from agriculture. It is a very abundant material in that sense,” says Malgorzata Zboinska.

3D printing and nanocellulose/ A resource efficient technique

The architectural industry is today surrounded by access to digital technologies which allows for a wider range of new techniques to be used, but there is a gap in the knowledge of how these techniques can be applied. According to the European Green Deal, as of 2030, buildings in Europe must be more resource-efficient, and this can be achieved through elevated reuse and recycling of materials, such as with nanocellulose, an upcycled, byproduct from industry. At the same time as buildings are to become more circular, cutting-edge digital techniques are highlighted as important leverages for achieving these goals.

“3D printing is a very resource efficient technique. It allows us to make products without other things such as dies and casting forms, so there is less waste material. It is also very energy efficient. The robotic 3D printing system we employ does not use heat, just air pressure. This saves a lot of energy as we are only working at room temperature,” says Malgorzata Zboinska.

The energy efficient process relies on the shear thinning properties of the nanocellulose hydrogel. When you apply pressure it liquifies allowing it to be 3D printed, but when you take away the pressure it maintains its shape. This allows the researchers to work without the energy intensive processes that are commonplace in the construction industry.

Malgorzata Zboinska and her team designed many different toolpaths to be used in the robotic 3D printing process to see how the nanocellulose hydrogel would behave when it dried in different shapes and patterns. These dried shapes could then be applied as a basis to design a wide array of architectural standalone components, such as lightweight room dividers, blinds, and wall panel systems. They could also form the basis for coatings of existing building components, such as tiles to clad walls, acoustic elements for damping sound, and combined with other materials to clad skeleton walls.

The future of greener building materials

“Traditional building materials are designed to last for hundreds of years. Usually, they have predictable behaviours and homogenous properties. We have concrete, glass and all kinds of hard materials that endure and we know how they will age over time. Contrary to this, biobased materials contain organic matter, that is from the outset designed to biodegrade and cycle back into nature. We, therefore, need to acquire completely new knowledge on how we could apply them in architecture, and how we could embrace their shorter life cycle loops and heterogenous behaviour patterns, resembling more those found in nature rather than in an artificial and fully controlled environment. Design researchers and architects are now intensely searching for ways of designing products made from these materials, both for function and for aesthetics,” says Malgorzata Zboinska.

This study provides the first steps to demonstrate the upscaling potentials of ambient-dried, 3D-printed nanocellulose membrane constructs, as well as a new understanding of the relationship between the design of the material’s deposition pathways via 3D printing, and the dimensional, textural, and geometric effects in the final constructs. This knowledge is a necessary stepping stone that will allow Malgorzata Zboinska and her team to develop, through further research, applications of nanocellulose in architectural products that need to meet specific functional and aesthetic user requirements.  

“The yet not fully known properties of novel biobased materials prompt architectural researchers to establish alternative approaches to designing these new products, not only in terms of the functional qualities, but also the acceptance from the users. The aesthetics of biobased materials are an important part of this. If we are to propose these biobased materials to society and people, we need to work with the design as well. This becomes a very strong element for the acceptance of these materials. If people do not accept them, we will not reach the goals of a circular economy and sustainable built environment”.

More about the research:

The research is presented in a paper: “Robotically 3D printed architectural membranes from ambient dried cellulose nanofibril-alginate hydrogel”, published in the journal Materials and Design.

The researchers involved in the study are Malgorzata A. Zboinska, Sanna Sämfors and Paul Gatenholm. The researchers were active at Chalmers University of Technology and the Wallenberg Wood Science Center, both in Sweden, at the time of the study.

This work was supported by Adlerbertska Research Foundation and Chalmers University of Technology’s Area of Advance Materials Science. The Knut and Alice Wallenberg Foundation is gratefully acknowledged for funding the Wallenberg Wood Science Center. The authors would also like to recognise the contribution of Karl Åhlund, who assisted in the robotic extrusion system development.

Fact box – previous research:

Printing with nanocellulose was first developed at Chalmers University of Technology within the Wallenberg Wood Science Center in 2015. This is the first time this technology is being scaled up towards applications in buildings.

Here’s a link to and a citation for the paper,

Robotically 3D printed architectural membranes from ambient dried cellulose nanofibril-alginate hydrogel by Malgorzata A. Zboinska, Sanna Sämfors, Paul Gatenholm. Materials & Design Volume 236, December 2023, 112472 DOI: https://doi.org/10.1016/j.matdes.2023.112472

This paper appears to be open access.

For the curious, here’s The European Green Deal.

Nanocellulose and food waste, an Australian perspective

A trio of Australian academics (Alan Labas, Benjamin Matthew Long, and Dylan Liu, all from Federation University Australia) have written a September 26, 2023 essay about nanocellulose derived from food waste for The Conversation, Note: Links have been removed,

Food waste is a global problem with approximately 1.3 billion tonnes of food wasted each year throughout the food lifecycle – from the farm to food manufacturers and households.

Across the food supply chain, Australians waste around 7.6 million tonnes of food each year. This costs our economy approximately A$36.6 billion annually.

In a recent study published in Bioresource Technology Reports, we have found a way to use food waste for making a versatile material known as nanocellulose. In particular, we used acid whey – a significant dairy production waste material that it usually difficult to dispose of.

For those who may not be familiar with nanocellulose, a lot of research was done here in Canada with a focus on using forest and agricultural waste products to produce nanocellulose. (See the CelluForce and Blue Goose Biorefineries websites for more about nanocellulose production, which in both their cases results in a specific material known as cellulose nanocrystals [CNC].) There’s more about the different kinds of nanocellulose later in this post.

The September 26, 2023 essay offers a good description of nanocellulose,

Nanocellulose is a biopolymer, which means it’s a naturally produced long chain of sugars. It has remarkable properties – bacterial nanocellulose is strong, chemically stable and biocompatible, meaning it’s not harmful to human cells. This makes it a highly marketable product with applications in packaging, wound treatments, drug delivery or food production.

Then, there’s this about the production process, from the September 26, 2023 essay, Note: A link has been removed,

The traditional approach for making nanocellulose can be expensive, uses large amounts of energy and takes a long time. Some types of nanocellulose production [emphasis mine] also use a chemical process that produces unwanted waste byproducts.

By contrast, our new approach uses just food waste and a symbiotic culture of bacteria and yeasts (SCOBY) – something you may be familiar with as a kombucha starter. Our process is low cost, consumes little energy and produces no waste.

… Lovers of home-brewed kombucha may actually be familiar with the raw nanocellulose material – it forms as a floating off-white structure called a pellicle. Some people already use this kombucha by-product as vegan leather.) A similar pellicle formed on our acid whey mixture.

I’m not sure if the “types of nanocellulose production” the writers are referring to are different types of nanocellose materials or different types of nanocellulose extraction.

A little more about nanocellulose

The Nanocellulose Wikipedia entry highlights the different materials that can be derived from nanocellulose, Note: Links have been removed,

Nanocellulose is a term referring to nano-structured cellulose. This may be either cellulose nanocrystal (CNC or NCC [nanocellulose crystal]), cellulose nanofibers (CNF) also called nanofibrillated cellulose (NFC), or bacterial nanocellulose, which refers to nano-structured cellulose produced by bacteria.

CNF is a material composed of nanosized cellulose fibrils with a high aspect ratio (length to width ratio). Typical fibril widths are 5–20 nanometers with a wide range of lengths, typically several micrometers. It is pseudo-plastic and exhibits thixotropy, the property of certain gels or fluids that are thick (viscous) under normal conditions, but become less viscous when shaken or agitated. When the shearing forces are removed the gel regains much of its original state. The fibrils are isolated from any cellulose containing source including wood-based fibers (pulp fibers) through high-pressure, high temperature and high velocity impact homogenization, grinding or microfluidization (see manufacture below).[1][2][3]

Nanocellulose can also be obtained from native fibers by an acid hydrolysis, giving rise to highly crystalline and rigid nanoparticles which are shorter (100s to 1000 nanometers) than the cellulose nanofibrils (CNF) obtained through homogenization, microfluiodization or grinding routes. The resulting material is known as cellulose nanocrystal (CNC).[4]

Nanochitin is similar in its nanostructure to nanocellulose.

Interestingly, Canadian development efforts are not mentioned in the essay until the very end, where we are lost in a plethora of other mentions, Note 1: Links have been removed; Note 2: All emphases mine,

A lthough wood-driven nanocellulose was first produced in 1983 by Herrick[7] and Turbak,[6] its commercial production postponed till 2010, mainly due to the high production energy consumption and high production cost. Innventia AB (Sweden) established the first nanocellulose pilot production plant 2010.[109] Companies and research institutes actively producing micro and nano fibrillated cellulose include: American Process (US), Borregaard (Norway), CelluComp (UK), Chuetsu Pulp and Paper (Japan), CTP/FCBA (France), Daicel (Japan), Dai-ichi Kyogo (Japan), Empa (Switzerland), FiberLean Technologies (UK), InoFib (France), Nano Novin Polymer Co. (Iran), Nippon Paper (Japan), Norske Skog (Norway), Oji Paper (Japan), RISE (Sweden), SAPPI (Netherlands), Seiko PMC (Japan), Stora Enso (Finland), Sugino Machine (Japan), Suzano (Brazil), Tianjin Haojia Cellulose Co. Ltd (China), University of Maine (US), UPM (Finland), US Forest Products Lab (US), VTT (Finland), and Weidmann Fiber Technology (Switzerland).[110] Companies and research institutes actively producing cellulose nanocrystals include: Alberta Innovates (Canada), American Process (US), Blue Goose Biorefineries (Canada), CelluForce (Canada), FPInnovations (Canada), Hangzhou Yeuha Technology Co. (China), Melodea (Israel/Sweden), Sweetwater Energy (US), Tianjin Haojia Cellulose Co. Ltd (China), and US Forest Products Lab (US).[110] Companies and research institutes actively producing cellulose filaments include: Kruger (Canada), Performance BioFilaments (Canada), and Tianjin Haojia Cellulose Co. Ltd (China).[110] Cellucomp (Scotland) produces Curran, a root-vegetable based nanocellulose.[111]

This leaves me with a couple of questions: Is my understanding of the nanocellulose story insular or Is the Wikipedia entry a little US-centric? It’s entirely possible the answer to both questions could be yes.

Why so much interest in nanocellulose? Money

From the September 26, 2023 essay, Note: A link has been removed,

Demand for nanocellulose is growing worldwide. The global market was valued at US$0.4 billion in 2022 (A$0.6bn) and is expected to grow to US$2 billion by 2030 (A$3.1bn). Bacterial nanocellulose produced from food waste can help to satisfy this demand.

This growth is in part due to how we can use nanocellulose instead of petroleum-based and other non-renewable materials in things like packaging. Among its desirable properties, nanocellulose is also fully biodegradable.

If you have time, do read the September 26, 2023 essay in its entirety.

H/t to September 27, 2023 news item on phys.org

Cellulose nanofibers as an alternative material for petroleum-based plastics?

According to an October 25, 2022 news item on phys.org, scientists at Osaka University (Japan) may have found a new material to replace petroleum-based plastic materials,

Single-use plastics have saved many lives by improving sanitation in health care. However, the sheer quantity of plastic waste—which can take from tens to hundreds of years to decompose—is a global pollution scourge. But now, in a study recently published in ACS Nano, researchers from The Institute of Scientific and Industrial Research (SANKEN) at Osaka University and collaborating partners have developed exceptionally versatile hydrogels and moldings that might replace conventional plastics.

An October 27, 2022 Osaka University press release (also on EurekAlert but published October 21, 2022), which originated the news item, tells the story behind the research,

The global scale of plastic waste urgently requires solutions and is being addressed from diverse perspectives. For example, in August 2022, National Geographic published a feature on recycling and repurposing plastic waste. Nevertheless, “the only long-term solution is to develop inexpensive, high-performance, plastic-like alternatives that don’t persist in the environment,” says Takaaki Kasuga, lead and senior author. “This is an active area of research, but the proposed alternatives to date haven’t met society’s needs.”

While researching the global need for a plastic substitute, Kasuga and coworkers were inspired by cellulose nanofibers. For example, these ultrasmall fibers help plants maintain rigid yet lightweight structures. In fact, on a pound-for-pound basis, cellulose nanofibers help wood to be—by some metrics—stronger than steel. The ability to tailor the hierarchical nature of such nanofibers has made them an active area of research in synthetic tissue and other bioengineering contexts.

Various techniques are currently available for molding nanofibers into a controlled orientation; i.e., to exhibit anisotropy. However, a simple technique that enables one to mold cellulose nanofibers from the nano- to macroscopic scale, on multiple spatial axes, has long been unavailable. To meet this need, Kasuga and coworkers used electrophoretic deposition to fabricate anisotropic cellulose-nanofiber-based hydrogels and moldings.

There were several especially impressive outcomes of this study. One, cellulose nanofibers were oriented horizontally, randomly, and vertically by simply changing the applied voltage. Two, a multilayer hydrogel was easily prepared with alternating nanofiber orientations, in a manner that’s reminiscent of biological tissue. Three, “we easily prepared complex architectures, such as microneedles and mouthpiece molds,” says Kasuga. “The uniform nanofiber orientation helped suppress hydrogel cracking, and thus resulted in a smooth surface, upon drying.”

The technique used in this study is not limited to cellulose nanofibers. For example, the researchers also used sodium alginate and nanoclay. Thus, multicomponent materials that exhibit controlled nanoscale orientations are also straightforward to prepare. An immediate application of this study is straightforward manufacturing of complex, hierarchical hydrogels and moldings over a wide range of spatial scales. Such ecofriendly hydrogels and moldings will be useful in healthcare, biotech, and other applications—and thus will help alleviate the need for petroleum-based plastics.

Here’s a link to and a citation for the paper,

One-Pot Hierarchical Structuring of Nanocellulose by Electrophoretic Deposition by Takaaki Kasuga, Tsuguyuki Saito, Hirotaka Koga, and Masaya Nogi. ACS Nano 2022, XXXX, XXX, XXX-XXX DOI: https://doi.org/10.1021/acsnano.2c06392 Publication Date: October 21, 2022 © 2022 The Authors. Published by American Chemical Society

This paper appears to be open access.

Spinning gold out of nanocellulose

If you’re hoping for a Rumpelstiltskin reference (there is more about the fairy tale at the end of this posting) and despite the press release’s headline, you won’t find it in this August 10, 2020 news item on Nanowerk,

When nanocellulose is combined with various types of metal nanoparticles, materials are formed with many new and exciting properties. They may be antibacterial, change colour under pressure, or convert light to heat.

“To put it simply, we make gold from nanocellulose”, says Daniel Aili, associate professor in the Division of Biophysics and Bioengineering at the Department of Physics, Chemistry and Biology at Linköping University.

The research group, led by Daniel Aili, has used a biosynthetic nanocellulose produced by bacteria and originally developed for wound care. The scientists have subsequently decorated the cellulose with metal nanoparticles, principally silver and gold. The particles, no larger than a few billionths of a metre, are first tailored to give them the properties desired, and then combined with the nanocellulose.

An August 10, 2020 Linköping University press release (also on EurekAlert), which originated the news item,expands on a few details about the work (sob … without mentioning Rumpelstiltskin),

“Nanocellulose consists of thin threads of cellulose, with a diameter approximately one thousandth of the diameter of a human hair. The threads act as a three-dimensional scaffold for the metal particles. When the particles attach themselves to the cellulose, a material that consists of a network of particles and cellulose forms”, Daniel Aili explains.

The researchers can determine with high precision how many particles will attach, and their identities. They can also mix particles of different metals and with different shapes – spherical, elliptical and triangular.

In the first part of a scientific article published in Advanced Functional Materials, the group describes the process and explains why it works as it does. The second part focusses on several areas of application.

One exciting phenomenon is the way in which the properties of the material change when pressure is applied. Optical phenomena arise when the particles approach each other and interact, and the material changes colour. As the pressure increases, the material eventually appears to be gold.

“We saw that the material changed colour when we picked it up in tweezers, and at first we couldn’t understand why”, says Daniel Aili.

The scientists have named the phenomenon “the mechanoplasmonic effect”, and it has turned out to be very useful. A closely related application is in sensors, since it is possible to read the sensor with the naked eye. An example: If a protein sticks to the material, it no longer changes colour when placed under pressure. If the protein is a marker for a particular disease, the failure to change colour can be used in diagnosis. If the material changes colour, the marker protein is not present.

Another interesting phenomenon is displayed by a variant of the material that absorbs light from a much broader spectrum visible light and generates heat. This property can be used for both energy-based applications and in medicine.

“Our method makes it possible to manufacture composites of nanocellulose and metal nanoparticles that are soft and biocompatible materials for optical, catalytic, electrical and biomedical applications. Since the material is self-assembling, we can produce complex materials with completely new well-defined properties,” Daniel Aili concludes.

Here’s a link to and a citation for the paper,

Self‐Assembly of Mechanoplasmonic Bacterial Cellulose–Metal Nanoparticle Composites by Olof Eskilson, Stefan B. Lindström, Borja Sepulveda, Mohammad M. Shahjamali, Pau Güell‐Grau, Petter Sivlér, Mårten Skog, Christopher Aronsson, Emma M. Björk, Niklas Nyberg, Hazem Khalaf, Torbjörn Bengtsson, Jeemol James, Marica B. Ericson, Erik Martinsson, Robert Selegård, Daniel Aili. Advanced Functional Materials DOI: https://doi.org/10.1002/adfm.202004766 First published: 09 August 2020

This paper is open access.

As for Rumpelstiltskin, there’s this abut the story’s origins and its cross-cultural occurrence, from its Wikipedia entry,

“Rumpelstiltskin” (/ˌrʌmpəlˈstɪltskɪn/ RUMP-əl-STILT-skin[1]) is a fairy tale popularly associated with Germany (where it is known as Rumpelstilzchen). The tale was one collected by the Brothers Grimm in the 1812 edition of Children’s and Household Tales. According to researchers at Durham University and the NOVA University Lisbon, the story originated around 4,000 years ago.[2][3] However, many biases led some to take the results of this study with caution.[4]

The same story pattern appears in numerous other cultures: Tom Tit Tot in England (from English Fairy Tales, 1890, by Joseph Jacobs); The Lazy Beauty and her Aunts in Ireland (from The Fireside Stories of Ireland, 1870 by Patrick Kennedy); Whuppity Stoorie in Scotland (from Robert Chambers’s Popular Rhymes of Scotland, 1826); Gilitrutt in Iceland; جعيدان (Joaidane “He who talks too much”) in Arabic; Хламушка (Khlamushka “Junker”) in Russia; Rumplcimprcampr, Rampelník or Martin Zvonek in the Czech Republic; Martinko Klingáč in Slovakia; “Cvilidreta” in Croatia; Ruidoquedito (“Little noise”) in South America; Pancimanci in Hungary (from A Csodafurulya, 1955, by Emil Kolozsvári Grandpierre, based on the 19th century folktale collection by László Arany); Daiku to Oniroku (大工と鬼六 “A carpenter and the ogre”) in Japan and Myrmidon in France.

An earlier literary variant in French was penned by Mme. L’Héritier, titled Ricdin-Ricdon.[5] A version of it exists in the compilation Le Cabinet des Fées, Vol. XII. pp. 125-131.

The Cornish tale of Duffy and the Devil plays out an essentially similar plot featuring a “devil” named Terry-top.

All these tales are Aarne–Thompson type 500, “The Name of the Helper”.[6]

Should you be curious about the story as told by the Brothers Grimm, here’s the beginning to get you started (from the grimmstories.com Rumpelstiltskin webpage),

There was once a miller who was poor, but he had one beautiful daughter. It happened one day that he came to speak with the king, and, to give himself consequence, he told him that he had a daughter who could spin gold out of straw. The king said to the miller: “That is an art that pleases me well; if thy daughter is as clever as you say, bring her to my castle to-morrow, that I may put her to the proof.”

When the girl was brought to him, he led her into a room that was quite full of straw, and gave her a wheel and spindle, and said: “Now set to work, and if by the early morning thou hast not spun this straw to gold thou shalt die.” And he shut the door himself, and left her there alone. And so the poor miller’s daughter was left there sitting, and could not think what to do for her life: she had no notion how to set to work to spin gold from straw, and her distress grew so great that she began to weep. Then all at once the door opened, and in came a little man, who said: “Good evening, miller’s daughter; why are you crying?”

Enjoy! BTW, should you care to, you can find three other postings here tagged with ‘Rumpelstiltskin’. I think turning dross into gold is a popular theme in applied science.

Desalination with nanowood

A new treatment for wood could make renewable salt-separating membranes. Courtesy: University of Maryland

An August 6, 2019 article by Adele Peters for Fast Company describes a ‘wooden’approach to water desalinization (also known as desalination),

“We are trying to develop a new type of membrane material that is nature-based,” says Z. Jason Ren, an engineering professor at Princeton University and one of the coauthors of a new paper in Science Advances about that material, which is made from wood. It’s designed for use in a process called membrane distillation, which heats up saltwater and uses pressure to force the water vapor through a membrane, leaving the salt behind and creating pure water. The membranes are usually made from a type of plastic. Using “nanowood” membranes instead can both improve the energy efficiency of the process and avoid the environmental problems of plastic.

An August 2, 2019 University of Maryland (UMD) news release provides more detail about the research,

A membrane made of a sliver of wood could be the answer to renewably sourced water cleaning. Most membranes that are currently used to distill fresh water from salty are made of polymers based on fossil fuels.

Inspired by the intricate system of water circulating in a tree, a research team from the University of Maryland, Princeton University, and the University of Colorado Boulder have figured out how to use a thin slice of wood as a membrane through which water vapor can evaporate, leaving behind salt or other contaminants.

“This work demonstrates another exciting energy/water application of nanostructured wood, as a high-performance membrane material,” said Liangbing Hu, a professor of materials science and engineering at UMD’s A. James Clark School of Engineering, who co-led the study.

The team chemically treated the wood to become hydrophobic, so that it more efficiently allows water vapor through, driven by a heat source like solar energy.

“This study discovered a new way of using wood materials’ unique properties as both an excellent insulator and water vapor transporter,” said Z. Jason Ren, a professor in environmental engineering who recently moved from CU Boulder to Princeton, and the other co-leader of the team that performed the study.

The researchers treat the wood so that it loses its lignin, the part of the wood that makes it brown and rigid, and its hemicellulose, which weaves in and out between cellulose to hold it in place. The resulting “nanowood” is treated with silane, a compound used to make silicon for computer chips. The semiconducting nature of the compound maintains the wood’s natural nanostructures of cellulose, and clings less to water vapor molecules as they pass through. Silane is also used in solar cell manufacturing.

The membrane looks like a thin piece of wood, seemingly bleached white, that is suspended above a source of water vapor. As the water heats and passes into the gas phase, the molecules are small enough to fit through the tiny channels lining the walls of the leftover cell structure. Water collected on the other side is now free of large contaminants like salt.
To test it, the researchers distilled water through it and found that it performed 1.2 times better than a conventional membrane.

“The wood membrane has very high porosity, which promotes water vapor transport and prevents heat loss,” said first author Dianxun Hou, who was a student at CU Boulder.
Inventwood, a UMD spinoff company of Hu’s research group, is working on commercializing wood based nanotechnologies.

Here’s a link to and a citation for the paper,

Hydrophobic nanostructured wood membrane for thermally efficient distillation by Dianxun Hou, Tian Li, Xi Chen, Shuaiming He, Jiaqi Dai, Sohrab A. Mofid, Deyin Hou, Arpita Iddya, David Jassby, Ronggui Yang, Liangbing Hu, and Zhiyong Jason Ren. Science Advances 02 Aug 2019: Vol. 5, no. 8, eaaw3203 DOI: 10.1126/sciadv.aaw3203

This paper appears to be open access.

In my brief survey of the paper, I noticed that the researchers were working with cellulose nanofibrils (CNF), a term which should be familiar for anyone following the nanocellulose story, such as it.

Bacterial cellulose nanofibers made strong and tough

Despite all the promise that nanocellulose offers, scientists don’t seem to have found significant applications for the material . In the software industry, they used to call it ‘a killer app’, i.e., an application everyone would start using (e.g. Facebook or Google) thereby making much money for its developer(s)..

This July 31, 2019 news item on phys.org describes research that may help scientists develop a nanocellulose ‘killer app’,

High-performance biomass-based nanocomposites are emerging as promising materials for future structural and functional applications due to their environmentally friendly, renewable and sustainable characteristics. Bio-sourced nanocelluloses [sic] (a kind of nanofibers [sic]) obtained from plants and bacterial fermentation are the most abundant raw materials on earth. They have attracted tremendous attention recently due to their attractive inherent merits including biodegradability, low density, thermal stability, global availability from renewable resources, as well as impressive mechanical properties. These features make them appropriate building blocks for spinning the next generation of advanced macrofibers for practical applications.

In past decades, various strategies have been pursued to gain cellulose-based macrofibers with improved strength and stiffness. However, nearly all of them have been achieved at the expense of elongation and toughness, because strength and toughness are always mutually exclusive for man-made structural materials. Therefore, this dilemma is quite common for previously reported cellulose-based macrofibers, which greatly limited their practical applications.

In a new article published in the National Science Review, Recently, a bionics research team led by Prof. Yu Shuhong from the University of Science and Technology of China (USTC) sought an inspiration to solve this problem from biological structures. …

A July 31, 2019 Science China Press news release on EurekAlert, which originated the news item, provides a few moretechnical details,

… They found that the widespread biosynthesized fibers, such as some plant fibers, spider silk and animal hairs, all have some similar features. They are both strong and tough, and have hierarchical helical structures across multiple length scales with stiff and strong nanoscale fibrous building blocks embedded in soft and energy dissipating matrices.

Inspired by these structural features in biosynthesized fibers, they presented a design strategy to make nanocellulose-based macrofibers with similar structural features. They used bacterial cellulose nanofibers as the strong and stiff building blocks, sodium alginate as the soft matrix. By combining a facile wet-spinning process with a subsequent multiple wet-twisting procedure, they successfully obtained biomimetic hierarchical helical nanocomposite macrofibers, and realized impressive improvement of their tensile strength, elongation and toughness simultaneously as expected.

This achievement certifies the validity of their bioinspired design and provides a potential route for further creating many other strong and tough nanocomposite fiber materials for diverse applications.

Here’s a link to and a citation for the paper,

Bioinspired hierarchical helical nanocomposite macrofibers based on bacterial cellulose nanofibers by Huai-Ling Gao, Ran Zhao, Chen Cui, Yin-Bo Zhu, Si-Ming Chen, Zhao Pan, Yu-Feng Meng, Shao-Meng Wen, Chuang Liu, Heng-An Wu, Shu-Hong Yu. National Science Review, nwz077, https://doi.org/10.1093/nsr/nwz077 Published: 21 June 2019

This paper appears to be open access.

Reading (2 of 2): Is zinc-infused underwear healthier for women?

This first part of this Reading ‘series’, Reading (1 of 2): an artificial intelligence story in British Columbia (Canada) was mostly about how one type of story, in this case,based on a survey, is presented and placed in one or more media outlets. The desired outcome is for more funding by government and for more investors (they tucked in an ad for an upcoming artificial intelligence conference in British Columbia).

This story about zinc-infused underwear for women also uses science to prove its case and it, too, is about raising money. In this case, it’s a Kickstarter campaign to raise money.

If Huha’s (that’s the company name) claims for ‘zinc-infused mineral undies’ are to be believed, the answer is an unequivocal yes. The reality as per the current research on the topic is not quite as conclusive.

The semiotics (symbolism)

Huha features fruit alongside the pictures of their underwear. You’ll see an orange, papaya, and melon in the kickstarter campaign images and on the company website. It seems to be one of those attempts at subliminal communication. Fruit is good for you therefore our underwear is good for you. In fact, our underwear (just like the fruit) has health benefits.

For a deeper dive into the world of semiotics, there’s the ‘be fruitful and multiply’ stricture which is found in more than one religious or cultural orientation and is hard to dismiss once considered.

There is no reason to add fruit to the images other than to suggest benefits from nature and fertility (or fruitfulness). They’re not selling fruit and these ones are not particularly high in zinc. If all you’re looking for is colour, why not vegetables or puppies?

The claims

I don’t have time to review all of the claims but I’ll highlight a few. My biggest problem with the claims is that there are no citations or links to studies, i.e., the research. So, something like this becomes hard to assess,

Most women’s underwear are made with chemical-based, synthetic fibers that lead to yeast and UTI [urinary tract infection] infections, odor, and discomfort. They’ve also been proven to disrupt human hormones, have been linked to cancer, pollute the planet aggressively, and stay in landfills far too long.

There’s more than one path to a UTI and/or odor and/or discomfort but I can see where fabrics that don’t breathe can exacerbate or cause problems of that nature. I have a little more difficulty with the list that follows. I’d like to see the research on underpants disrupting human hormones. Is this strictly a problem for women or could men also be affected? (If you should know, please leave a comment.)

As for ‘linked to cancer’, I’m coming to the conclusion that everything is linked to cancer. Offhand, I’ve been told peanuts, charcoal broiled items (I think it’s the char), and my negative thoughts are all linked to cancer.

One of the last claims in the excerpted section, ‘pollute the planet aggressively’ raises this question.When did underpants become aggressive’?

The final claim seems unexceptional. Our detritus is staying too long in our landfills. Of course, the next question is: how much faster do the Huha underpants degrade in a landfill? That question is not addressed in Kickstarter campaign material.

Talking to someone with more expertise

I contacted Dr. Andrew Maynard, Associate Director at Arizona State University (ASU) School for the Future of Innovation in Society, He has a PhD in physics and longstanding experience in research and evaluation of emerging technologies (for many years he specialized in nanoparticle analysis and aerosol exposure in occupational settings),.

Professor Maynard is a widely recognized expert and public commentator on emerging technologies and their safe and responsible development and use, and has testified before [US] congressional committees on a number of occasions. 

None of this makes him infallible but I trust that he always works with integrity and bases his opinions on the best information at hand. I’ve always found him to be a reliable source of information.

Here’s what he had to say (from an October 25, 2019 email),

I suspect that their claims are pushing things too far – from what I can tell, professionals tend to advise against synthetic underwear because of the potential build up of moisture and bacteria and the lack of breathability, and tend to suggest natural materials – which indicating that natural fibers and good practices should be all most people need. I haven’t seen any evidence for an underwear crisis here, and one concern is that the company is manufacturing a problem which they then claim to solve. That said, I can’t see anything totally egregious in what they are doing. And the zinc presence makes sense in that it prevents bacterial growth/activity within the fabric, thus reducing the chances of odor and infection.

Pharmaceutical grade zinc and research into underwear

I was a little curious about ‘pharmaceutical grade’ zinc as my online searches for a description were unsuccessful. Andrew explained that the term likely means ‘high purity’ zinc suitable for use in medications rather than the zinc found in roofing panels.

After the reference to ‘pharmaceutical grade’ zinc there’s a reference to ‘smartcel sensitive Zinc’. Here’s more from the smartcel sensitive webpage,

smartcel™ sensitive is skin friendly thanks to zinc oxide’s soothing and anti-inflammatory capabilities. This is especially useful for people with sensitive skin or skin conditions such as eczema or neurodermitis. Since zinc is a component of skin building enzymes, it operates directly on the skin. An active exchange between the fiber and the skin occurs when the garment is worn.

Zinc oxide also acts as a shield against harmful UVA and UVB radiation [it’s used in sunscreens], which can damage our skin cells. Depending on the percentage of smartcel™ sensitive used in any garment, it can provide up to 50 SPF.

Further to this, zinc oxide possesses strong antibacterial properties, especially against odour causing bacteria, which helps to make garments stay fresh longer. *

I couldn’t see how zinc helps the pH balance in anyone’s vagina as claimed in the Kickstarter campaign and smartcel, on its ‘sensitive’ webpage, doesn’t make that claim but I found an answer in an April 4, 2017 Q&A (question and answer) interview by Jocelyn Cavallo for Medium,

What women need to know about their vaginal p

Q & A with Dr. Joanna Ellington

A woman’s vagina is a pretty amazing body part. Not only can it be a source of pleasure but it also can help create and bring new life into the world. On top of all that, it has the extraordinary ability to keep itself clean by secreting natural fluids and maintaining a healthy pH to encourage the growth of good bacteria and discourage harmful bacteria from moving in. Despite being so important, many women are never taught the vital role that pH plays in their vaginal health or how to keep it in balance.

We recently interviewed renowned Reproductive Physiologist and inventor of IsoFresh Balancing Vaginal Gel, Dr. Joanna Ellington, to give us the low down on what every woman needs to know about their vaginal pH and how to maintain a healthy level.

What is pH?

Dr. Ellington: PH is a scale of acidity and alkalinity. The measurements range from 0 to 14: a pH lower than 7 is acidic and a pH higher than 7 is considered alkaline.

What is the “perfect” pH level for a woman’s vagina?

Dr. E.: For most women of a reproductive age vaginal pH should be 4.5 or less. For post-menopausal women this can go up to about 5. The vagina will naturally be at a high pH right after sex, during your period, after you have a baby or during ovulation (your fertile time).

Are there diet and environmental factors that affect a women’s vaginal pH level?

Dr. E.: Yes, iron zinc and manganese have been found to be critical for lactobacillus (healthy bacteria) to function. Many women don’t eat well and should supplement these, especially if they are vegetarian. Additionally, many vegetarians have low estrogen because they do not eat the animal fats that help make our sex steroids. Without estrogen, vaginal pH and bacterial imbalance can occur. It is important that women on these diets ensure good fat intake from other sources, and have estrogen and testosterone and iron levels checked each year.

Do clothing and underwear affect vaginal pH?

Dr. E.: Yes, tight clothing and thong underwear [emphasis mine] have been shown in studies to decrease populations of healthy vaginal bacteria and cause pH changes in the vagina. Even if you wear these sometimes, it is important for your vaginal ecosystem that loose clothing or skirts be worn some too.

Yes, Dr. Ellington has the IsoFresh Balancing Vaginal Gel and whether that’s a good product should be researched but all of the information in the excerpt accords with what I’ve heard over the years and fits in nicely with what Andrew said, zinc in underwear could be useful for its antimicrobial properties. Also, note the reference to ‘thong underwear’ as a possible source of difficulty and note that Huha is offering thong and very high cut underwear.

Of course, your underwear may already have zinc in it as this research suggests (thank you, Andrew, for the reference),

Exposure of women to trace elements through the skin by direct contact with underwear clothing by Thao Nguyen & Mahmoud A. Saleh. Journal of Environmental Science and Health, Part A Toxic/Hazardous Substances and Environmental Engineering Volume 52, 2017 – Issue 1 Pages 1-6 DOI: https://doi.org/10.1080/10934529.2016.1221212 Published online: 09 Sep 2016

This paper is behind a paywall but I have access through a membership in the Canadian Academy of Independent Scholars. So, here’s the part I found interesting,

… The main chemical pollutants present in textiles are dyes containing carcinogenic amines, metals, pentachlorophenol, chlorine bleaching, halogen carriers, free formaldehyde, biocides, fire retardants and softeners.[1] Metals are also found in textile products and clothing are used for many purposes: Co [cobalt], Cu [copper], Cr [chromium] and Pb [lead] are used as metal complex dyes, Cr as pigments mordant, Sn as catalyst in synthetic fabrics and as synergists of flame retardants,Ag [silver] as antimicrobials and Ti [titanium] and Zn [zinc] as water repellents and odor preventive agents.[2–5] When present in textile materials, the toxic elements mentioned above represent not only a major environmental problem in the textile industry but also they may impose potential danger to human health by absorption through the skin.[6,7] [emphasis mine] Chronic exposure to low levels of toxic elements has been associated with a number of adverse human health effects.[8–11] Also exposure to high concentration of elements which are considered as essential for humans such as Cu, Co, Fe [iron], Mn [manganese] or Zn among others, can also be harmful.[12] [emphasis mine] Co, Cr, Cu and Ni [nitrogen] are skin sensitizers,[13,14] which may lead to contact dermatitis, also Cr can lead to liver damage, pulmonary congestion and cancer.[15] [emphasis mine] The purpose of the present study was to determine the concentrations of a number of elements in various skin-contact clothes. For risk estimations, the determination of the extractable amounts of heavy metals is of importance, since they reflect their possible impact on human health. [p. 2 PDF]

So, there’s the link to cancer. Maybe.

Are zinc-infused undies a good idea?

It could go either way. (For specifics about the conclusions reached in the study, scroll down to the Ooops! subheading.) I like the idea of using sustainable Eucalyptus-based material (TencelL) for the underwear as I have heard that cotton isn’t sustainably cultivated. As for claims regarding the product’s environmental friendliness, it’s based on wood, specifically, cellulose, which Canadian researchers have been experimenting with at the nanoscale* and they certainly have been touting nanocellulose as environmentally friendly. Tencel’s sustainability page lists a number of environmental certifications from the European Union, Belgium, and the US.

*Somewhere in the Kickstarter campaign material, there’s a reference to nanofibrils and I’m guessing those nanofibrils are Tencel’s wood fibers at the nanoscale. As well, I’m guessing that smartcel’s fabric contains zinc oxide nanoparticles.

Whether or not you need more zinc is something you need to determine for yourself. Finding out if the pH balance in your vagina is within a healthy range might be a good way to start. It would also be nice to know how much zinc is in the underwear and whether it’s being used antimicrobial properties and/or as a source for one of minerals necessary for your health.

How the Kickstarter campaign is going

At the time of this posting, they’ve reached a little over $24,000 with six days left. The goal was $10,000. Sadly, there are no questions in the FAQ (frequently asked questions).

Reading tips

It’s exhausting trying to track down authenticity. In this case, there were health and environmental claims but I do have a few suggestions.

  1. Look at the imagery critically and try to ignore the hyperbole.
  2. How specific are the claims? e.g., How much zinc is there in the underpants?
  3. Who are their experts and how trustworthy are the agencies/companies mentioned?
  4. If research is cited, are the publishers reputable and is the journal reputable?
  5. Does it make sense given your own experience?
  6. What are the consequences if you make a mistake?

Overblown claims and vague intimations of disease are not usually good signs. Conversely, someone with great credential may not be trustworthy which is why I usually try to find more than one source for confirmation. The person behind this campaign and the Huha company is Alexa Suter. She’s based in Vancouver, Canada and seems to have spent most of her time as a writer and social media and video producer with a few forays into sales and real estate. I wonder if she’s modeling herself and her current lifestyle entrepreneurial effort on Gwyneth Paltrow and her lifestyle company, Goop.

Huha underwear may fulfill its claims or it may be just another pair of underwear or it may be unhealthy. As for the environmentally friendly claims, let’s hope that the case. On a personal level, I’m more hopeful about that.

Regardless, the underwear is not cheap. The smallest pledge that will get your underwear (a three-pack) is $65 CAD.

Ooops! ETA: November 8, 2019:

I forgot to include the conclusion the researchers arrived at and some details on how they arrived at those conclusions. First, they tested 120 pairs of underpants in all sorts of colours and made in different parts of the world.

Second, some underpants showed excessive levels of metals. Cotton was the most likely material to show excess although nylon and polyester can also be problematic. To put this into proportion and with reference to zinc, “Zn exceeded the limit in 4% of the tested samples
and was found mostly in samples manufactured in China.” [p. 6 PDF] Finally, dark colours tested for higher levels of metals than light colours.

While it doesn’t mention underpants as such, there’s a November 8, 2019 article ‘Five things everyone with a vagina should know‘ by Paula McGrath for BBC news online. McGrath’s health expert is Dr. Jen Gunter, a physician whose specialties are obstetrics, gynaecology, and pain.

Nanocellulose sensors: 3D printed and biocompatible

I do like to keep up with nanocellulose doings, especially when there’s some Canadian involvement, and an October 8, 2019 news item on Nanowerk alerted me to a newish application for the product,

Physiological parameters in our blood can be determined without painful punctures. Empa researchers are currently working with a Canadian team to develop flexible, biocompatible nanocellulose sensors that can be attached to the skin. The 3D-printed analytic chips made of renewable raw materials will even be biodegradable in future.

The idea of measuring parameters that are relevant for our health via the skin has already taken hold in medical diagnostics. Diabetics, for example, can painlessly determine their blood sugar level with a sensor instead of having to prick their fingers.

An October 8, 2019 Empa (Swiss Federal Laboratories for Materials Science and Technology) press release, which originated the news item, provides more detail,

A transparent foil made of wood

Nanocellulose is an inexpensive, renewable raw material, which can be obtained in form of crystals and fibers, for example from wood. However, the original appearance of a tree no longer has anything to do with the gelatinous substance, which can consist of cellulose nanocrystals and cellulose nanofibers. Other sources of the material are bacteria, algae or residues from agricultural production. Thus, nanocellulose is not only relatively easy and sustainable to obtain. Its mechanical properties also make the “super pudding” an interesting product. For instance, new composite materials based on nanocellulose can be developed that could be used as surface coatings, transparent packaging films or even to produce everyday objects like beverage bottles.

Researchers at Empa’s Cellulose & Wood Materials lab and Woo Soo Kim from the Simon Fraser University [SFU] in Burnaby, Canada, are also focusing on another feature of nanocellulose: biocompatibility. Since the material is obtained from natural resources, it is particularly suitable for biomedical research.

With the aim of producing biocompatible sensors that can measure important metabolic values, the researchers used nanocellulose as an “ink” in 3D printing processes. To make the sensors electrically conductive, the ink was mixed with silver nanowires. The researchers determined the exact ratio of nanocellulose and silver threads so that a three-dimensional network could form.

Just like spaghetti – only a wee bit smaller

It turned out that cellulose nanofibers are better suited than cellulose nanocrystals to produce a cross-linked matrix with the tiny silver wires. “Cellulose nanofibers are flexible similar to cooked spaghetti, but with a diameter of only about 20 nanometers and a length of just a few micrometers,” explains Empa researcher Gilberto Siqueira.

The team finally succeeded in developing sensors that measure medically relevant metabolic parameters such as the concentration of calcium, potassium and ammonium ions. The electrochemical skin sensor sends its results wirelessly to a computer for further data processing. The tiny biochemistry lab on the skin is only half a millimeter thin.

While the tiny biochemistry lab on the skin – which is only half a millimeter thin – is capable of determining ion concentrations specifically and reliably, the researchers are already working on an updated version. “In the future, we want to replace the silver [nano] particles with another conductive material, for example on the basis of carbon compounds,” Siqueira explains. This would make the medical nanocellulose sensor not only biocompatible, but also completely biodegradable.

I like the images from Empa better than the ones from SFU,

Using a 3D printer, the nanocellulose “ink” is applied to a carrier plate. Silver particles provide the electrical conductivity of the material. Image: Empa
Empa researcher Gilberto Siqueira demonstrates the newly printed nanocellulose circuit. After a subsequent drying, the material can be further processed. Image: Empa

SFU produced a news release about this work back in February 2019. Again, I prefer what the Swiss have done because they’re explaining/communicating the science, as well as , communicating benefits. From a February 13, 2019 SFU news release (Note: Links have been removed),

Simon Fraser University and Swiss researchers are developing an eco-friendly, 3D printable solution for producing wireless Internet-of-Things (IoT) sensors that can be used and disposed of without contaminating the environment. Their research has been published as the cover story in the February issue of the journal Advanced Electronic Materials.

SFU professor Woo Soo Kim is leading the research team’s discovery, which uses a wood-derived cellulose material to replace the plastics and polymeric materials currently used in electronics.

Additionally, 3D printing can give flexibility to add or embed functions onto 3D shapes or textiles, creating greater functionality.

“Our eco-friendly, 3D-printed cellulose sensors can wirelessly transmit data during their life, and then can be disposed without concern of environmental contamination,” says Kim, a professor in the School of Mechatronic Systems Engineering. The SFU research is being carried out at PowerTech Labs in Surrey, which houses several state-of-the-art 3D printers used to advance the research.

“This development will help to advance green electronics. For example, the waste from printed circuit boards is a hazardous source of contamination to the environment. If we are able to change the plastics in PCB to cellulose composite materials, recycling of metal components on the board could be collected in a much easier way.”

Kim’s research program spans two international collaborative projects, including the latest focusing on the eco-friendly cellulose material-based chemical sensors with collaborators from the Swiss Federal Laboratories for Materials Science.

He is also collaborating with a team of South Korean researchers from the Daegu Gyeongbuk Institute of Science and Technology’s (DGIST)’s department of Robotics Engineering, and PROTEM Co Inc, a technology-based company, for the development of printable conductive ink materials.

In this second project, researchers have developed a new breakthrough in the embossing process technology, one that can freely imprint fine circuit patterns on flexible polymer substrate, a necessary component of electronic products.

Embossing technology is applied for the mass imprinting of precise patterns at a low unit cost. However, Kim says it can only imprint circuit patterns that are imprinted beforehand on the pattern stamp, and the entire, costly stamp must be changed to put in different patterns.

The team succeeded in developing a precise location control system that can imprint patterns directly resulting in a new process technology. The result will have widespread implications for use in semiconductor processes, wearable devices and the display industry.

This paper was made available online back in December 2018 and then published in print in February 2019. As to why there’d be such large gaps between the paper’s publication dates and the two institution’s news/press releases, it’s a mystery to me. In any event, here’s a link to and a citation for the paper,

3D Printed Disposable Wireless Ion Sensors with Biocompatible Cellulose Composites by Taeil Kim, Chao Bao, Michael Hausmann, Gilberto Siqueira, Tanja Zimmermann, Woo Soo Kim. Advanced Electronic Materials DOI: https://doi.org/10.1002/aelm.201970007 First published online December 19, 2018. First published in print: 08 February 2019 (Adv. Electron. Mater. 2/2109) Volume 5, Issue 2 February 2019 1970007

This paper is behind a paywall.

A nanocomposite biomaterial heart valve from the University of British Columbia (Canada)

I wish the folks at the University of British Columbia (UBC) would include more technical/scientific information in their news releases about research. For those who do like a little more technical information, I included the paper’s abstract at the end of this post.

A March 25, 2019 news item on ScienceDaily trumpets the UBC (Okanagan campus) research,

Researchers at UBC have created the first-ever nanocomposite biomaterial heart-valve developed to reduce or eliminate complications related to heart transplants.

By using a newly developed technique, the researchers were able to build a more durable valve that enables the heart to adapt faster and more seamlessly.

A March 25, 2019 UBC news release (also on EurekAlert) by Patty Wellborn, which originated the news item, gives an accessible description of the ‘new’ valve,

Assistant Professor Hadi Mohammadi runs the Heart Valve Performance Laboratory (HVPL) through UBC Okanagan’s School of Engineering. Lead author on the study, he says the newly developed valve is an example of a transcatheter heart valve, a promising new branch of cardiology. These valves are unique because they can be inserted into a patient through small incisions rather than opening a patient’s chest–a procedure that is generally safer and much less invasive.

“Existing transcatheter heart valves are made of animal tissues, most often the pericardium membrane from a cow’s heart, and have had only moderate success to date,” explains Mohammadi. “The problem is that they face significant implantation risks and can lead to coronary obstruction and acute kidney injury.”

The new valve solves that problem by using naturally derived nanocomposites–a material assembled with a variety of very small components–including gels, vinyl and cellulose. The combination of their new material with the non-invasive nature of transcatheter heart valves makes this new design very promising for use with high-risk patients, according to Mohammadi.

“Not only is the material important but the design and construction of our valve means that it lowers stress on the valve by as much as 40 per cent compared to valves currently available,” says Dylan Goode, a graduate researcher at the HVPL. “It is uniquely manufactured in one continuous form, so it gains strength and flexibility to withstand the circulatory complications that can arise following transplantation.”

Working with researchers from Kelowna General Hospital and Western University, the valve will now undergo vigorous testing to perfect its material composition and design. The testing will include human heart simulators and large animal in-vivo studies. If successful, the valve will then proceed to clinical patient testing.

“This has the potential to become the new standard in heart valve replacement and to provide a safer, longer-term solution for many patients.”

The new design was highlighted in a paper published this month in the Journal of Engineering in Medicine with financial support from the Natural Sciences and Engineering Research Council of Canada [NSERC] .

Here’s a link to and a citation for the paper,

Proposed percutaneous aortic valve prosthesis made of cryogel by Hadi Mohammadi, Dylan Goode, Guy Fradet, Kibret Mequanint. Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2019; 095441191983730 DOI: 10.1177/0954411919837302 First Published March 20, 2019

This paper is behind a paywall.

As promised, here’s the abstract,

Transcatheter heart valves are promising for high-risk patients. Generally, their leaflets are made of pericardium stented in a Nitinol basket. Despite their relative success, they are associated with significant complications such as valve migration, implantation risks, stroke, coronary obstruction, myocardial infraction, acute kidney injury (which all are due to the release of detached solid calcific pieces in to the blood stream) and expected issues existing with tissue valves such as leaflet calcification. This study is an attempt to fabricate the first ever polymeric percutaneous valves made of cryogel following the geometry and mechanical properties of porcine aortic valve to address some of the above-mentioned shortcomings. A novel, one-piece, tricuspid percutaneous valve, consisting of leaflets made entirely from the hydrogel, polyvinyl alcohol cryogel reinforced by bacterial cellulose natural nanocomposite, attached to a Nitinol basket was developed and demonstrated. Following the natural geometry of the valve, a novel approach was applied based on the revolution about an axis of a hyperboloid shape. The geometry was modified based on avoiding sharp warpage of leaflets and removal of the central opening orifice area of the valve when valve is fully closed using the finite element analysis. The modified geometry was replaced by a cloud of (control) points and was essentially converted to Bezier surfaces for further adjustment. A cavity mold was then designed and fabricated to form the valve. The fabricated valve was sewn into the Nitinol basket which is covered by Dacron cloth. The models presented in this study merit further development and revisions for both aortic and mitral positions.

So, this new valve partially consists of bacterial cellulose and the design is based on porcine (pig) valves. Cellulose is the most abundant organic material on earth and if it forms part of the nanocomposite, I’d expect to see the word ‘nanocellulose’ mentioned somewhere. What puzzles me is the ‘bacterial cellulose’, a term that is unfamiliar to me. Anyone who cares to clarify the matter for me, please feel free to leave a comment.

Regarding the pig valve, I understand that heart patients who require valves have a choice of a pig valve or a mechanical valve. Apparently, people with porcine valves don’t need to take drugs to counteract rejection amongst other advantages but the valves do have a shorter life span (10 to 15 years) in addition to the other shortcomings mentioned in the abstract.

Assuming I properly understand the abstract, this ‘nanocomposite’ valve could combine the advantages of the mechanical and porcine valves while offering more durability than either one.

Again, should anyone care to increase my understanding of the valves and the advantages of this new one, please do leave a comment.

A fire-retardant coating made of renewable nanocellulose materials

Firefighters everywhere are likely to appreciate the efforts of researchers at Texas A&M University (US) to a develop a non-toxic fire retardant coating. From a February 12, 2019 news item on Nanowerk (Note: A link has been removed),

Texas A&M University researchers are developing a new kind of flame-retardant coating using renewable, nontoxic materials readily found in nature, which could provide even more effective fire protection for several widely used materials.

Dr. Jaime Grunlan, the Linda & Ralph Schmidt ’68 Professor in the J. Mike Walker ’66 Department of Mechanical Engineering at Texas A&M, led the recently published research that is featured on the cover of a recent issue of the journal Advanced Materials Interfaces (“Super Gas Barrier and Fire Resistance of Nanoplatelet/Nanofibril Multilayer Thin Films”).

Successful development and implementation of the coating could provide better fire protection to materials including upholstered furniture, textiles and insulation.

“These coatings offer the opportunity to reduce the flammability of the polyurethane foam used in a variety of furniture throughout most people’s homes,” Grunlan noted.

A February 8, 2019 Texas A&M University news release (also on EurekAlert) by Steve Kuhlmann, which originated the news item, describes the work being done in collaboration with a Swedish team in more detail,

The project is a result of an ongoing collaboration between Grunlan and a group of researchers at KTH Royal Institute of Technology in Stockholm, Sweden, led by Lars Wagberg. The group, which specializes in utilizing nanocellulose, provided Grunlan with the ingredients he needed to complement his water-based coating procedure.

In nature, both the cellulose – a component of wood and various sea creatures – and clay – a component in soil and rock formations – act as mechanical reinforcements for the structures in which they are found.

“The uniqueness in this current study lies in the use of two naturally occurring nanomaterials, clay nanoplatelets and cellulose nanofibrils,” Grunlan said. “To the best of our knowledge, these ingredients have never been used to make a heat shielding or flame-retardant coating as a multilayer thin film deposited from water.”

Among the benefits gained from using this method include the coating’s ability to create an excellent oxygen barrier to plastic films – commonly used for food packaging – and better fire protection at a lower cost than other, more toxic ingredients traditionally used flame-retardant treatments.

To test the coatings, Grunlan and his colleagues applied the flexible polyurethane foam – often used in furniture cushions – and exposed it to fire using a butane torch to determine the level of protection the compounds provided.

While uncoated polyurethane foam immediately melts when exposed to flame, the foam treated with the researchers’ coating prevented the fire from damaging any further than surface level, leaving the foam underneath undamaged.

“The nanobrick wall structure of the coating reduces the temperature experienced by the underlying foam, which delays combustion,” Grunlan said. “This coating also serves to promote insulating char formation and reduces the release of fumes that feed a fire.”

With the research completed, Grunlan said the next step for the overall flame-retardant project is to transition the methods into industry for implementation and further development. 

Here’s a link to and a citation for the paper,

Super Gas Barrier and Fire Resistance of Nanoplatelet/Nanofibril Multilayer Thin Films by Shuang Qin, Maryam Ghanad Pour, Simone Lazar, Oruç Köklükaya, Joseph Gerringer, Yixuan Song, Lars Wågberg, Jaime C. Grunlan. Advanced Materials Interfaces Volume 6, Issue 2 January 23, 2019 1801424 DOI: https://doi.org/10.1002/admi.201801424 First published online: 16 November 2018

This paper is behind a paywall.