How to Clear the Cache on an Android Smartphone

Given enough time, all gadgets slow down—smartphones included. Your Android might start slowing down randomly, and there are times when even a reboot won’t really fix things. You don’t necessarily have to shell out hundreds (or thousands) of dollars on a new phone, though. Your old one might just need a clean out.

When nothing else seems to be speeding your Android phone back up, you should try some cache maintenance. As you use your Android phone, the apps (and especially Chrome) start saving temporary files it thinks you’ll need. These are used to speed up page loads and to keep older files in memory. That’s great when you have a fast flagship with loads of extra memory to spare. But if your Android phone is a bit older, you’ll be surprised how much lighter things become once you let go of some of that cache.

In fact, it’s a good idea to do this regularly—even every couple of weeks. It might seem a bit counterintuitive, as the cache is supposed to keep your phone faster, but lightening the digital load is often the way to go for older devices.

How to clear the cache for any app on an Android smartphone

Sometimes it’s a third-party app gone rogue that’s hogging all that cache memory. Android’s Settings app will make it easy to find such a culprit. Go to Storage > Apps to see a list of all installed apps. From the Menu, switch to the Sort by Size option, and you’ll see the apps that are most hogging up the storage. The exact steps to find the Apps section might be different depending on your Android smartphone, but you can search for Storage or Apps to get there. 

Go through the apps, and choose an app to clear the cache. Apps like Facebook, Instagram, and TikTok are all major offenders of the cache system. In the app screen, tap the Clear Cache button to see the cache data instantly disappear. Now, go back to the list, and do this again, and again, at least for the top 10 apps that are taking up most of the cache.

How to clear the cache in Chrome 

The biggest cache hog on your smartphone is likely Chrome, and if you’ve never cleared the cache, you might notice quite the difference before and after. If you don’t use Chrome, do this for your default browser. The changes will be the same. 

Open the Chrome browser, tap Menu and go to History > Clear Browsing Data. First, switch to the All Time option at the top and make sure you’ve checked the Cached images and files option below. Then, tap the Clear Data button to clear the cache.

Keep doing this regularly for Chrome and the rest of your apps on Android. If you have an iPhone or iPad, you should do the same there as well. 



Source: LifeHacker – How to Clear the Cache on an Android Smartphone

The Best Video Game Characters Of 2023

Nearly every conversation I’ve had about Baldur’s Gate 3 this year has started with a series of questions: “Can I see your character? And who are you romancing?” More often than not, I’m more interested in hearing how the characters people make and meet are helping them write their own stories than I am talking about…

Read more…



Source: Kotaku – The Best Video Game Characters Of 2023

AMD WBRF Ready For Linux 6.8 To Mitigate WiFi Radio Interference

Since earlier this year AMD has been working on Linux support for WBRF for mitigating WiFi radio frequency interference (RFI) with their latest Ryzen 7000 and forthcoming Ryzen 8000 series mobile processors. That work looks like it will be ready to land in Linux 6.8…

Source: Phoronix – AMD WBRF Ready For Linux 6.8 To Mitigate WiFi Radio Interference

Daily Telescope: Hubble images a dazzling star cluster 158,000 light-years away

This striking image shows the densely packed globular cluster known as NGC 2210, which is situated in the Large Magellanic Cloud.

Enlarge / This striking image shows the densely packed globular cluster known as NGC 2210, which is situated in the Large Magellanic Cloud. (credit: ESA/Hubble & NASA, A. Sarajedini, F. Niederhofer)

Welcome to the Daily Telescope. There is a little too much darkness in this world and not enough light, a little too much pseudoscience and not enough science. We’ll let other publications offer you a daily horoscope. At Ars Technica, we’re going to take a different route, finding inspiration from very real images of a universe that is filled with stars and wonder.

Good morning. It’s December 11, and today’s photograph takes us to the Large Magellanic Cloud, which is one of the very nearest galaxies to our own and lies about 158,000 light-years away.

This Hubble Space Telescope image showcases a brilliant globular cluster within the Large Magellanic Cloud. Such clusters are tightly bound and gravitationally stable, meaning millions of stars persist in a (relatively) tightly confined space for billions of years. This makes them an attractive target for astronomers seeking to study older stars.

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Source: Ars Technica – Daily Telescope: Hubble images a dazzling star cluster 158,000 light-years away

How Parents Can Learn Mental Health First Aid (and Why You Should)

Maybe you learned how to use an Epipen when your child was diagnosed with food allergy; you took a CPR course before your baby was born; and you have first aid supplies stashed in your car, office, and home. Injuries and accidents are inevitable in life, and we want to be prepared.

But the reality is that one out of five youth and adolescents has a mental health condition—so shouldn’t parents be prepared to provide first aid for mental health as well? You can learn skills now to recognize signs of a problem and help your child find the appropriate professional help if they need it. if you’ve ever tried to help someone through a mental health crisis, you know how frightening and helpless you can feel—so why not empower yourself now, just in case your child experiences a crisis down the road?

What is Mental Health First Aid?

Mental Health First Aid (MHFA) is training to help someone who is in a mental health crisis, or just beginning to have a mental health problem. This type of training can be especially useful for parents and people who work with children, like teachers and coaches.

You can choose between taking a course to help adults with mental health problems or a course tailored for helping adolescents, aged 12-18. In both cases, you can choose between in-person training (if it’s available in your area), blended in-person (with a virtual component and a live component), or a completely virtual course.

What you’ll learn

A one-day MFHA course usually takes about six to eight hours, covering discussion topics, exercises, and opportunities to practice your new skills.

The youth MFHA training course emphasizes early intervention, since 75 percent of mental illnesses start by the time a person is in their mid-20s.

Mental health first aid is based on a five-step action plan called ALGEE:

  • Assess for risk of suicide or harm.

  • Listen without judgment.

  • Give reassurance and information.

  • Encourage appropriate professional help.

  • Encourage self-help and other support strategies.

You will also learn warning signs and risk factors for mental health problems like eating disorders, ADHD, depression, mood disorders, anxiety, trauma, psychosis, and substance abuse. During training, you will become familiar with information about treatment options and self-help strategies so you can share those options with the person you’re helping. You will be able to support young people experiencing the following situations:

  • Panic attacks

  • Suicidal thoughts or behaviors

  • Nonsuicidal self-injury

  • Hallucinations or delusions

  • Overdose or withdrawal from substances

  • A traumatic event

  • Bullying

  • Social media problems

Besides taking in information through the course materials and lecture, you will have opportunities to practice through role-playing.

Benefits for parents

Any teen could experience one of the mental health scenarios listed above, and many parents may not know where to start supporting them. It may feel powerless to tell your child to “calm down” or “cheer up” and see no improvement in their mental state. MHFA training teaches you how to assess their symptoms, start conversations, and reach out for professional help.

While the goal is to teach you to help someone struggling with their mental health, a nice side benefit is that your mental health literacy will increase too. Research shows that MHFA training improves the mental health of both the trainee and the person they support.

Other benefits of MHFA training:

  • Reduced stigma around mental illness and substance use

  • Increased empathy

  • More confidence to help someone in distress

  • Learning tools to support your own mental health

How to find an MHFA course

Follow this link to find the right mental health first aid training option for you. Filter courses by location, date, language, and in-person or virtual. The course is usually completed in one day and may cost $50-100.



Source: LifeHacker – How Parents Can Learn Mental Health First Aid (and Why You Should)

Homey Pro review: A very particular set of home automation skills

Homey Pro hub sitting on a desk, with a blue-ish rainbow glow on bottom

Enlarge / The Homey Pro, settling in for some quiet network check-ins at dusk. (credit: Kevin Purdy)

I know there are people who will want to buy the Homey Pro. I’ve seen them on social media and in various home automation forums, and I’ve even noticed them in the comments on this website. For this type of person, the Homey Pro might serve as a specialized, locally focused smart home hub, one that’s well worth the cost. But you should be really, truly certain that you’re that person before you take a $400 leap with it.

Homey Pro is a smart home hub pitched primarily at someone who wants to keep things local as much as possible, forgoing phone apps, speakers, and cloud connections. That means using the Homey Pro to boost a primarily Zigbee or Z-Wave network, while also looping in local Wi-Fi, Bluetooth, and even infrared remotes. It’s for someone willing to pay $400 for a device that offers robust local or cloud backups, professional design, advanced automation, and even a custom scripting language, along with access to some “experiments” and still-in-progress tech like Matter and Thread. It’s for someone who might want to add a select cloud service or two to their home, but not because they have no other option.

But this somebody has also, somehow, not already invested in Home Assistant, Hubitat, or HomeBridge, which are more open to both add-on hardware (like new capabilities added on by USB stick or GPIO pins) and deep tinkering. It’s someone who is willing to check that every device they want to control will work with Homey. While the device offers a pretty sizable range of apps and integrations, it’s far from the near-universal nature of major open-source projects or even the big smart home platforms. And you have to do a little checking further, still, to ensure that individual products are supported, not just the brand.

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Source: Ars Technica – Homey Pro review: A very particular set of home automation skills

Today’s Wordle Hints (and Answer) for Monday, December 11, 2023

If you’re looking for the Wordle answer for December 11, 2023 read on. We’ll share some clues, tips, and strategies, and finally the solution. Today’s puzzle is another easy one; I got it in three. Beware, there are spoilers below for December 11, Wordle #905! Keep scrolling if you want some hints (and then the answer) to today’s Wordle game.

How to play Wordle

Wordle lives here on the New York Times website. A new puzzle goes live every day at midnight, your local time.

Start by guessing a five-letter word. The letters of the word will turn green if they’re correct, yellow if you have the right letter in the wrong place, or gray if the letter isn’t in the day’s secret word at all. For more, check out our guide to playing Wordle here, and my strategy guide here for more advanced tips. (We also have more information at the bottom of this post, after the hints and answers.)

Ready for the hints? Let’s go!


Does today’s Wordle have any unusual letters?

We’ll define common letters as those that appear in the old typesetters’ phrase ETAOIN SHRDLU. (Memorize this! Pronounce it “Edwin Shirdloo,” like a name, and pretend he’s a friend of yours.)

All five are common letters today!

Can you give me a hint for today’s Wordle?

It’s the place where you live, perhaps.

Does today’s Wordle have any double or repeated letters?

Nope, five different letters today.

How many vowels are in today’s Wordle?

There are three vowels today, all different.

What letter does today’s Wordle start with?

Today’s word starts with H.

What letter does today’s Wordle end with?

Today’s word ends with E.

What is the solution to today’s Wordle?

Ready? Today’s word is HOUSE.

How I solved today’s Wordle

The green ___SE was a great start, but I’m still potentially missing some vowels, so I go with my trusty second of TOUCH next. Looks like we’re dealing with _OUSE with a yellow H. It’s as good as solved: today’s word must be HOUSE.

Wordle 905 3/6

⬜⬜⬜🟩🟩
⬜🟩🟩⬜🟨
🟩🟩🟩🟩🟩

A primer on Wordle basics

The idea of Wordle is to guess the day’s secret word. When you first open the Wordle game, you’ll see an empty grid of letters. It’s up to you to make the first move: type in any five-letter word. 

Now, you can use the colors that are revealed to get clues about the word: 

  • Green means you correctly guessed a letter, and it’s in the correct position. (For example, if you guess PARTY, and the word is actually PURSE, the P and R will be green.)

  • Yellow means the letter is somewhere in the word, but not in the position you guessed it. (For example, if you guessed PARTY, but the word is actually ROAST, the R, A and T will all be yellow.)

  • Gray means the letter is not in the solution word at all. (If you guessed PARTY and everything is gray, then the solution cannot be PURSE or ROAST.)

With all that in mind, guess another word, and then another, trying to land on the correct word before you run out of chances. You get six guesses, and then it’s game over.

The best starter words for Wordle

What should you play for that first guess? The best starters tend to contain common letters, to increase the chances of getting yellow and green squares to guide your guessing. (And if you get all grays when guessing common letters, that’s still excellent information to help you rule out possibilities.) There isn’t a single “best” starting word, but the New York Times’s Wordle analysis bot has suggested starting with one of these:

  • CRANE

  • TRACE

  • SLANT

  • CRATE

  • CARTE

Meanwhile, an MIT analysis found that you’ll eliminate the most possibilities in the first round by starting with one of these:

  • SALET

  • REAST

  • TRACE

  • CRATE

  • SLATE

Other good picks might be ARISE or ROUND. Words like ADIEU and AUDIO get more vowels in play, but you could argue that it’s better to start with an emphasis on consonants, using a starter like RENTS or CLAMP. Choose your strategy, and see how it plays out.

How to win at Wordle

We have a few guides to Wordle strategy, which you might like to read over if you’re a serious student of the game. This one covers how to use consonants to your advantage, while this one focuses on a strategy that uses the most common letters. In this advanced guide, we detail a three-pronged approach for fishing for hints while maximizing your chances of winning quickly.

The biggest thing that separates Wordle winners from Wordle losers is that winners use their guesses to gather information about what letters are in the word. If you know that the word must end in -OUND, don’t waste four guesses on MOUND, ROUND, SOUND, and HOUND; combine those consonants and guess MARSH. If the H lights up in yellow, you know the solution.

One more note on strategy: the original Wordle used a list of about 2,300 solution words, but after the game was bought by the NYT, the game now has an editor who hand-picks the solutions. Sometimes they are slightly tricky words that wouldn’t have made the original list, and sometimes they are topical. For example, FEAST was the solution one Thanksgiving. So keep in mind that there may be a theme.

Wordle alternatives

If you can’t get enough of five-letter guessing games and their kin, the best Wordle alternatives, ranked by difficulty, include:



Source: LifeHacker – Today’s Wordle Hints (and Answer) for Monday, December 11, 2023

Today's NYT Connections Hints (and Answer) for Monday, December 11, 2023

If you’re looking for the Connections answer for Monday, December 11, 2023, read on—I’ll share some clues, tips, and strategies, and finally the solutions to all four categories. Along the way, I’ll explain the meanings of the trickier words and we’ll learn how everything fits together. Beware, there are spoilers below for December 11, NYT Connections #183! Read on if you want some hints (and then the answer) to today’s Connections game. 

If you want an easy way to come back to our Connections hints every day, bookmark this page. You can also find our past hints there as well, in case you want to know what you missed in a previous puzzle.

Below, I’ll give you some oblique hints at today’s Connections answers. And farther down the page, I’ll reveal the themes and the answers. Scroll slowly and take just the hints you need!

NYT Connections board for December 11, 2023: SILK, BLOW, LACE, LAND, SOLE, BABY, VELVET, TONGUE, PERCH, PACKAGE, SETTLE, SPEECH, SATIN, EYELET, ROOST, CHIFFON.

Credit: Connections/NYT


Does today’s Connections game require any special knowledge?

If you know fashion or sewing, you’ll pick out one of the categories pretty easily.

Hints for the themes in today’s Connections puzzle

Here are some spoiler-free hints for the groupings in today’s Connections:

  • Yellow category – Sewing material.

  • Green category – Alighting on a branch.

  • Blue category – Put on your shoes.

  • Purple category – Other entries for this category could be “pizza” or “me from evil.”

Does today’s Connections game involve any wordplay?

The purple category is on the trickier side. It’s not exactly a fill-in-the-blank, but sort of along those lines–the words are all part of similar phrases.

Ready to hear the answers? Keep scrolling if you want a little more help.


BEWARE: Spoilers follow for today’s Connections puzzle!

We’re about to give away some of the answers. Scroll slowly if you don’t want the whole thing spoiled. (The full solution is a bit further down.)

What are the ambiguous words in today’s Connections?

  • An EYELET is a small hole in fabric. LACE can be made of EYELETs, but the holes that your shoe LACEs go through are also called EYELETs.

  • You use your TONGUE for SPEECH, but those words are not in the same category today. 

  • SOLE and PERCH are both fish, but there are no fish in the puzzle today. 

  • CHIFFON can refer to a pie with a light, fluffy texture, but it’s named after a sheer SILK fabric used in dresses.

  • To ROOST is to rest on a branch or in a henhouse; hence the word ROOSTer. (Which seems to have been invented in the 1800s so people wouldn’t have to say “cock.”) 

  • Speaking of words that might not be polite to say, BLOW does not refer here to sex or drugs. A BLOW can be a punch or a kick.

What are the categories in today’s Connections?

  • Yellow: LUXURIOUS FABRICS

  • Green: COME DOWN TO REST

  • Blue: SHOE PARTS

  • Purple: THINGS THAT ARE DELIVERED

DOUBLE BEWARE: THE SOLUTION IS BELOW

Ready to learn the answers to today’s Connections puzzle? I give them all away below.

What are the yellow words in today’s Connections?

The yellow grouping is considered to be the most straightforward. The theme for today’s yellow group is LUXURIOUS FABRICS and the words are: CHIFFON, SATIN, SILK, VELVET.

What are the green words in today’s Connections?

The green grouping is supposed to be the second-easiest. The theme for today’s green category is COME DOWN TO REST and the words are: PERCH, ROOST, SETTLE, LAND.

What are the blue words in today’s Connections?

The blue grouping is the second-hardest. The theme for today’s blue category is SHOE PARTS and the words are: EYELET, LACE, SOLE, TONGUE.

What are the purple words in today’s Connections?

The purple grouping is considered to be the hardest. The theme for today’s purple category is THINGS THAT ARE DELIVERED and the words are: BABY, BLOW, PACKAGE, SPEECH.

How I solved today’s Connections

First I consider the fancy fabrics: SILK, CHIFFON, LACE, EYELET, and a few others. Then I wonder if SOLE and PERCH are meant to be fish. Finally I see the sneaker parts: LACE, EYELET, SOLE, and TONGUE. 🟦

The fabrics, then, are SILK, SATIN, VELVET, and CHIFFON. 🟨 (Satin, velvet, and chiffon were all originally made from silk, by the way.) 

Now we have ways of coming to rest, as a bird does when alighting on a branch: ROOST, SETTLE, LAND, PERCH. 🟩 

What are we left with? Things that are delivered. You deliver a BABY (OK), a PACKAGE (sure), a SPEECH (I’ll allow it), and …a BLOW? Oh! In the sense of a punch or kick. Yes, of course, that’s what I was thinking. 🟪

Connections 
Puzzle #183
🟦🟦🟦🟦
🟨🟨🟨🟨
🟩🟩🟩🟩
🟪🟪🟪🟪

How to play Connections

I have a full guide to playing Connections, but here’s a refresher on the rules:

First, find the Connections game either on the New York Times website or in their Crossword app. You’ll see a game board with 16 tiles, each with one word or phrase. Your job is to select a group of four tiles that have something in common. Often they are all the same type of thing (for example: RAIN, SLEET, HAIL, and SNOW are all types of wet weather) but sometimes there is wordplay involved (for example, BUCKET, GUEST, TOP TEN, and WISH are all types of lists: bucket list, guest list, and so on).

Select four items and hit the Submit button. If you guessed correctly, the category and color will be revealed. (Yellow is easiest, followed by green, then blue, then purple.) If your guess was incorrect, you’ll get a chance to try again.

You win when you’ve correctly identified all four groups. But if you make four mistakes before you finish, the game ends and the answers are revealed.

How to win Connections

The most important thing to know to win Connections is that the groupings are designed to be tricky. Expect to see overlapping groups. For example, one puzzle seemed to include six breakfast foods: BACON, EGG, PANCAKE, OMELET, WAFFLE, and CEREAL. But BACON turned out to be part of a group of painters along with CLOSE, MUNCH, and WHISTLER, and EGG was in a group of things that come by the dozen (along with JUROR, ROSE, and MONTH). So don’t hit “submit” until you’ve confirmed that your group of four contains only those four things.

If you’re stuck, another strategy is to look at the words that seem to have no connection to the others. If all that comes to mind when you see WHISTLER is the painting nicknamed “Whistler’s Mother,” you might be on to something. When I solved that one, I ended up googling whether there was a painter named Close, because Close didn’t fit any of the obvious themes, either.

Another way to win when you’re stuck is, obviously, to read a few helpful hints–which is why we share these pointers every day. Check back tomorrow for the next puzzle!



Source: LifeHacker – Today’s NYT Connections Hints (and Answer) for Monday, December 11, 2023

Unvanquished 0.54.1 Released With Rendering Fixes & Better Bots

Unvanquished has been a promising open-source first person shooter game in development for over a decade. It started out putting monthly alpha releases and quite a brisk development pace but in recent years the releases have been much less frequent. This year started out with Unvanquished 0.54 being released and in now approaching the end of the year is seeing a new point release…

Source: Phoronix – Unvanquished 0.54.1 Released With Rendering Fixes & Better Bots

Ten Top Holiday Tech Gift Ideas Under $100 For Big Deal Savings

Ten Top Holiday Tech Gift Ideas Under $100 For Big Deal Savings
We’ve only got 15 more days until Christmas, so now is the time to take advantage of some hot, last-minute deals. This week, we present to you the top 10 tech gifts for under-$100.

Leading off, we have the JBL Flip 6 at $99.95 or 23% off the regular price. This portable Bluetooth speaker claims up to 12 hours of playtime with powerful bass

Source: Hot Hardware – Ten Top Holiday Tech Gift Ideas Under 0 For Big Deal Savings

NVIDIA CFO Teases Intel Foundry Services Deal And It Could Be A Great Partnership

NVIDIA CFO Teases Intel Foundry Services Deal And It Could Be A Great Partnership
NVIDIA CFO Colette Kress spoke about the possibility of having Intel as a foundry partner during an interview at the UBS Global Technology Conference. At the moment NVIDIA uses both Samsung and TSMC for their chip fabrication needs, with TSMC handling the majority of the duty.

TSMC is currently the strongest foundry partner, and works on

Source: Hot Hardware – NVIDIA CFO Teases Intel Foundry Services Deal And It Could Be A Great Partnership

ULA chief says Vulcan rocket will slip to 2024 after ground system issues

ULA's Vulcan rocket rolls to the launch pad for testing.

Enlarge / ULA’s Vulcan rocket rolls to the launch pad for testing. (credit: United Launch Alliance)

United Launch Alliance will not see the debut of its next-generation Vulcan rocket in 2023, as previously planned.

The launch company’s chief executive, Tory Bruno, announced the delay on the social media site X on Sunday. United Launch Alliance had been working toward a debut flight of the lift booster on Christmas Eve, from Cape Canaveral Space Force Station in Florida.

Bruno made the announcement after the company attempted to complete a fueling test of the entire rocket, known as a wet dress rehearsal.

Read 8 remaining paragraphs | Comments



Source: Ars Technica – ULA chief says Vulcan rocket will slip to 2024 after ground system issues

Pentagon’s X-37B Space Force Warplane Soon To Take Flight On A Secret Mission

Pentagon’s X-37B Space Force Warplane Soon To Take Flight On A Secret Mission
The US Space Force (USSF) is about to launch its X-37B reusable and unmanned mini space shuttle on a secret mission. Mission specifics are sparse, but many believe that it represents the US military’s warning to (primarily) Russian and Chinese rivals of its intention of achieving space superiority. 

With six missions already under its belt,

Source: Hot Hardware – Pentagon’s X-37B Space Force Warplane Soon To Take Flight On A Secret Mission

The Week's Hottest Gaming Takes, From The Game Awards And Fallout To GTA 6

It was a big week for the scantily clad at Kotaku this week, with both GTA 6 and Like a Dragon: Infinite Wealth giving players plenty of skin. We’re also feeling very excited about the new Fallout show, but decidedly less enthusiastic about the minimal focus on the actual awards at this week’s Game Awards.

Read more…



Source: Kotaku – The Week’s Hottest Gaming Takes, From The Game Awards And Fallout To GTA 6

Why scientists are making transparent wood

a transparent piece of wood on top of a green leaf

Enlarge / See-through wood has a number of interesting properties that researchers hope to exploit. (credit: WILEY‐VCH VERLAG GMBH & CO. KGAA, WEINHEIM)

Thirty years ago, a botanist in Germany had a simple wish: to see the inner workings of woody plants without dissecting them. By bleaching away the pigments in plant cells, Siegfried Fink managed to create transparent wood, and he published his technique in a niche wood technology journal. The 1992 paper remained the last word on see-through wood for more than a decade, until a researcher named Lars Berglund stumbled across it.

Berglund was inspired by Fink’s discovery, but not for botanical reasons. The materials scientist, who works at KTH Royal Institute of Technology in Sweden, specializes in polymer composites and was interested in creating a more robust alternative to transparent plastic. And he wasn’t the only one interested in wood’s virtues. Across the ocean, researchers at the University of Maryland were busy on a related goal: harnessing the strength of wood for nontraditional purposes.

Now, after years of experiments, the research of these groups is starting to bear fruit. Transparent wood could soon find uses in super-strong screens for smartphones; in soft, glowing light fixtures; and even as structural features, such as color-changing windows.

“I truly believe this material has a promising future,” says Qiliang Fu, a wood nanotechnologist at Nanjing Forestry University in China who worked in Berglund’s lab as a graduate student.

Wood is made up of countless little vertical channels, like a tight bundle of straws bound together with glue. These tube-shaped cells transport water and nutrients throughout a tree, and when the tree is harvested and the moisture evaporates, pockets of air are left behind. To create see-through wood, scientists first need to modify or get rid of the glue, called lignin, that holds the cell bundles together and provides trunks and branches with most of their earthy brown hues. After bleaching lignin’s color away or otherwise removing it, a milky-white skeleton of hollow cells remains.

This skeleton is still opaque, because the cell walls bend light to a different degree than the air in the cell pockets does—a value called a refractive index. Filling the air pockets with a substance like epoxy resin that bends light to a similar degree to the cell walls renders the wood transparent.

The material the scientists worked with is thin—typically less than a millimeter to around a centimeter thick. But the cells create a sturdy honeycomb structure, and the tiny wood fibers are stronger than the best carbon fibers, says materials scientist Liangbing Hu, who leads the research group working on transparent wood at the University of Maryland in College Park. And with the resin added, transparent wood outperforms plastic and glass: In tests measuring how easily materials fracture or break under pressure, transparent wood came out around three times stronger than transparent plastics like Plexiglass and about 10 times tougher than glass.

“The results are amazing, that a piece of wood can be as strong as glass,” says Hu, who highlighted the features of transparent wood in the 2023 Annual Review of Materials Research.

The process also works with thicker wood but the view through that substance is hazier because it scatters more light. In their original studies from 2016, Hu and Berglund both found that millimeter-thin sheets of the resin-filled wood skeletons let through 80 to 90 percent of light. As the thickness gets closer to a centimeter, light transmittance drops: Berglund’s group reported that 3.7-millimeter-thick wood—roughly two pennies thick—transmitted only 40 percent of light.

The slim profile and strength of the material means it could be a great alternative to products made from thin, easily shattered cuts of plastic or glass, such as display screens. The French company Woodoo, for example, uses a similar lignin-removing process in its wood screens, but leaves a bit of lignin to create a different color aesthetic. The company is tailoring its recyclable, touch-sensitive digital displays for products, including car dashboards and advertising billboards.

But most research has centered on transparent wood as an architectural feature, with windows a particularly promising use, says Prodyut Dhar, a biochemical engineer at the Indian Institute of Technology Varanasi. Transparent wood is a far better insulator than glass, so it could help buildings retain heat or keep it out. Hu and colleagues have also used polyvinyl alcohol, or PVA—a polymer used in glue and food packaging—to infiltrate the wood skeletons, making transparent wood that conducts heat at a rate five times lower than that of glass, the team reported in 2019 in Advanced Functional Materials.

And researchers are coming up with other tweaks to increase wood’s ability to hold or release heat, which would be useful for energy-efficient buildings. Céline Montanari, a materials scientist at RISE Research Institutes of Sweden, and colleagues experimented with phase-change materials, which flip from storing to releasing heat when they change from solid to liquid, or vice-versa. By incorporating polyethylene glycol, for example, the scientists found that their wood could store heat when it was warm and release heat as it cooled, work they published in ACS Applied Materials and Interfaces In 2019.

Transparent wood windows would therefore be stronger and aid in temperature control better than traditional glass, but the view through them would be hazy, more similar to frosted glass than a regular window. However, the haziness could be an advantage if users want diffuse light: Since thicker wood is strong, it could be a partially load-bearing light source, Berglund says, potentially acting as a ceiling that provides soft, ambient light to a room.

Hu and Berglund have continued to toy with ways to bestow new properties on transparent wood. Around five years ago, Berglund and colleagues at KTH and Georgia Institute of Technology found they could mimic smart windows, which can switch from transparent to tinted to block visibility or the Sun’s rays. The researchers sandwiched an electrochromic polymer—a substance that can change color with electricity—between layers of transparent wood coated with an electrode polymer to conduct electricity. This created a pane of wood that changes from clear to magenta when users run a small electrical current through it.

More recently, the two groups have shifted their attention to improving the sustainability of transparent wood production. For example, the resin used to fill the wood scaffolding is typically a petroleum-derived plastic product, so it’s better to avoid using it, Montanari says. As a replacement, she and colleagues invented a fully bio-based polymer derived from citrus peels. The team first combined acrylic acid and limonene, a chemical extracted from lemon and orange rinds that’s found in essential oils. Then they impregnated delignified wood with it. Even with a fruity filling, the bio-based transparent wood maintained its mechanical and optical properties, withstanding around 30 megapascals of pressure more than regular wood and transmitting around 90 percent of light, the researchers reported in 2021 in Advanced Science.

Hu’s lab, meanwhile, recently reported in Science Advances a greener lignin-bleaching method that leans on hydrogen peroxide and UV radiation, further reducing the energy demands of production. The team brushed wood slices ranging from about 0.5 to 3.5 millimeters in thickness with hydrogen peroxide, then left them in front of UV lamps to mimic the Sun’s rays. The UV bleached away the pigment-containing parts of lignin but left the structural parts intact, thus helping to retain more strength in the wood.

These more environmentally friendly approaches help limit the amount of toxic chemicals and fossil-based polymers used in production, but for now, glass still has lower end-of-life environmental impacts than transparent wood, according to an analysis by Dhar and colleagues in Science of the Total Environment. Embracing greener production schemes and scaling up manufacturing are two steps necessary to add transparent wood to mainstream markets, researchers say, but it will take time. However, they are confident it can be done and believe in its potential as a sustainable material.

“When you’re trying to achieve sustainability, you don’t only want to match the properties of fossil-based materials,” Montanari says. “As a scientist, I want to surpass this.”

Jude Coleman is an Oregon-based freelance journalist who covers ecology, climate change, and the environment. Read more of her work at judecoleman.com. This article originally appeared in Knowable Magazine, an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter.

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Source: Ars Technica – Why scientists are making transparent wood

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