Category Archives: Musings & News

Coffee Grounds Replace Plastic in 3D Printing

Making coffee: a pour-over (photo from Wikimedia Commons)

3 October 2023

… and there’s a Pittsburgh connection.

When you make coffee, what do you do with the spent grounds? Some people compost them at home or use them as fertilizer. You can even turn them into an insect repellent or natural cleaning scrub. But most of us just throw them away.

Use coffee grounds (photo by Kate St. John)

When Michael Rivera was in grad school at Carnegie Mellon he spent a lot of time at Arriviste Coffee Roasters in Shadyside. At the time, Arriviste paid a service to collect their coffee grounds but the service stopped during the pandemic and the spent grounds piled up.

Arriviste Coffee Roasters (banner from Facebook page)

Rivera was working on 3D printing technology and saw how to solve two problems at the same time: (1) Reuse coffee grounds instead of throwing them away and (2) Reduce plastic use in 3D printing.

The vast majority of 3D printing machines use thermoplastic to make new objects by melting it and reforming it with the print head.

Four 3D printers making medical face visors (photo from Wikimedia Commons)

It can take a lot of plastic to make an object, particularly a large one.

3D printer creating a statue at 3D Printer Shootout Testing – Day 3 (photo from Wikimedia Commons)

Rivera is now a postdoctoral researcher at University of Colorado Boulder where he further fleshed out his idea of using spent coffee grounds instead of plastic.

Rivera and colleagues mix dried spent coffee grounds with two common food additives — cellulose gum and xanthan gum — and then mix in water.

“You’re pretty much shooting for the consistency of peanut butter,” Rivera said.

You can’t load that ooze directly into a 3D printer. First, Rivera does a little jury-rigging, modifying a printer with plastic tubes and a syringe filled with coffee paste. When dried, the coffee grounds material is about as tough as unreinforced concrete.

Science Daily: 3D printing with coffee: Turning used grounds into caffeinated creations

Here’s a coffee-based 3D print, photo embedded from the Ars Technica article.

Coffee-based 3D print (photo by Michael Rivera embedded from ars technica article)

The resulting objects are completely recyclable.

“You can make a lot of things with coffee grounds,” River said. “And when you don’t want it anymore, you can throw it back into a coffee grinder and use the grounds to print again.”

Science Daily: 3D printing with coffee: Turning used grounds into caffeinated creations

Here’s how Rivera and his team make 3D objects with coffee grounds.

video embedded from Univ of Colorado Boulder on YouTube

Read more about the project in Ars Technica: Don’t throw out those used coffee grounds—use them for 3D printing instead and the published study in July 2023 in the Association for Computing Machinery.

p.s. Does the reuse of coffee grounds sound familiar? I blogged about it a few weeks ago but forgot to mention it until Jennie Barker made the comments below.

(photos from Wikimedia Commons, Kate St. John, Arriviste Coffee Roasters Facebook banner, and embedded photo from Ars Technica; click on the captions to see the originals)

Want Stronger Concrete? Add Coffee Grounds

Fresh ground coffee (photo by Kate St. John)

24 September 2023

A new study from Australia has found that adding used coffee grounds to concrete makes it 30% stronger!

Block of concrete (photo from Wikimedia Commons)

To prepare coffee as a concrete additive, the study team collected spent coffee grounds and turned them into biochar in a low-energy process without oxygen at 350 degrees Celsius.

Used coffee grounds (photo by Kate St. John)

Not only did coffee make the concrete 30% stronger but the already used grounds did not end up in a landfill, a significant savings since the world’s coffee drinkers create 10 billion kg (11 million tons!) of spent coffee every year.

If the idea catches on, coffee waste will reduce the need for sand in concrete …

Portable concrete plant in Austin, TX (photo by Larry D. Moore via Wikimedia Commons)

… which will reduce the need to mine so much sand, a finite resource.

Sand mine (photo from Wikimedia Commons)

Will piles of sand at concrete plants be replaced by piles of biochar coffee? Imagine what it would smell like at a cement plant, like this one along the Parkway East near Uptown, satellite view below.

Google satellite view of Heidelburg Materials Concrete / Lindy Paving, 2nd Avenue, Pittsburgh

Read more about this innovation at Science Daily: Coffee Offers Performance Boost for Concrete.

I hope it catches on.

(credits in the captions)

Where Is This Mosaic?

Beautiful mosaic. Where is it? (photo from Wikimedia Commons)

16 August 2023

Beautifully colored tiles. An intricate pattern. What floor, wall or ceiling holds this mosaic? Click here to see a closeup.

The photo caption at Wikimedia Commons has the answer:

Woody Dicot Stem Vascular Cylinder in One Year Liriodendron, photo from Berkshire Community College Bioscience Image Library, Pittsfield, Massachusetts.

The mosaic is made of cells in the woody stem of a one year old tuliptree (Liriodendron tulipifera), sliced thin and magnified 100 times. The colors and shapes are specific to the species and its age. The description indicates that things change at lot in a one year old tulip tree.

The mosaic slice was photographed in 2014 at Berkshire Community College in Pittsfield, MA from a sapling that probably grew in Western Massachusetts.

When a tulip tree grows up it has leaves and flowers like this.

Tulip tree leafout, Schenley Park, 28 April 2014 (photo by Kate St. John)
Tulip tree flower, 4 May 2017 (photo by Kate St. John)

Still beautiful and intricate even when not magnified.

For more information on the mosaic image see the description of the image here. It is so technical that I need a glossary to figure out what it means.

(photos from Wikimedia Commons and Kate St. John)

Bird News and Pebble Art

Celebrity in Central Park, Flaco the Eurasian eagle-owl, February 2023 (photo from Wikimedia Commons)

28 July 2023

A selection of photos and videos this month around the web:

In February a Eurasian eagle-owl named Flaco escaped from the Central Park Zoo and became a celebrity. He’s still hanging out in July.

In Florida, swallow-tailed kites are preparing to migrate.

In Europe, migration has already begun across the Strait of Gibraltar.

And finally, a pebbly tiger on the beach in Devon, UK by Beach4Art.

(embedded with links, Twitter and Facebook)

Check the Air for DNA

DNA of giraffe and elephant were both detected in the air outside Copenhagen Zoo (photos from Wikimedia Commons)

18 July 2023

We’ve been paying attention to air quality this summer as Canadian wildfire smoke blows into town. The smoke that reaches us, called smog or soot in the chart below, is labelled PM2.5 by air monitors (the particles are less than 2.5 micrometers in diameter). As you can see there’s a lot of other stuff in the air that the monitors are not analyzing — but they could. In the past few years scientists have discovered that we can check the air for DNA.

Atmospheric particulate matter, types and sizes in micrometres (?m) (diagram from Wikipedia) The diagram has been updated to show PM2.5 with a red line

In 2020 an environmental DNA (eDNA) study in water led to eDNA studies in the air when a fish inventory compared trawling surveys (shown below) to DNA analysis of seawater samples. Science Magazine reported, “Overall, the team found about a 70% match between species abundance recorded by eDNA and trawls.”

Fishery biologists and deckhands working up a big tow on the F/V Excalibur. All catches
are first divided into baskets by species. Photo: NOAA Fisheries

In 2021 Mark Johnson, a graduate student at Texas Tech, realized that pollen and plant fragments are such a big component of air quality that he decided to compare manual plant surveys to eDNA measurements at Texas Tech University’s Native Rangeland.

The two methods complemented each other. Manual surveys detected 80 species while eDNA found 91 using the devices pictured below. According to Science Magazine, “eDNA was better at finding easily overlooked species with small flowers, such as weakleaf bur ragweed. But people were better at spotting plants too rare to release much eDNA, particularly when they had showy flowers, such as the chocolate daisy.”

The Big Spring Number Eight dust traps that were used to collect airborne eDNA (photo from Mark Johnson’s studay at Texas Tech)

It was only a matter of time before similar air monitoring was used to detect animals.

Two recent studies — one in the UK, the other in Copenhagen — collected and analyzed air samples for animal DNA. And they found it. To prove their equipment, each study located air samplers near a zoo and both found zoo animal DNA. According to NPR, the Copenhagen study “picked up 49 animal species including rhinos, giraffes and elephants. ‘We even detected the guppy that was living in the pond in the rainforest house.'”

Guppy (photo from Wikimedia Commons)

And so we’ve come full circle from detecting fish DNA in water to detecting it in the air.

Read more about the animal eDNA studies at WESA-FM: Scientists vacuum zoo animals’ DNA out of the air.

p.s. There is speculation that this technique could help us inventory endangered species.

(photo credits are in the captions; click on the links to see the originals)

The Essence of Iridescence

Anna’s hummingbird (photo from Wikimedia Commons)

16 July 2023

What causes iridescence? What makes a hummingbird glow red in one position, then dull green when he moves his head?

video from NDTV on YouTube

Other dazzlers, including beetles, shells, and rocks, have similar physical iridescent characteristics.

Six-spotted tiger beetle in Maryland (photo from Wikimedia Commons)
Nautilus shell sliced in half (photo from Wikimedia Commons)
Nautilus shell cut in half (photo from Wikimedia Commons)
Iridescence on anthracite, a.k.a. peacock coal (photo from Wikimedia Commons)
Sun dog — an iridescent cloud (photo from Wikimedia Commons)

Find out what causes iridescence in this 16 minute video from PBS @BeSmart. If you don’t have much time, watch the first 4+ minutes about hummingbirds.

video embedded from PBS @BeSmart

p.s. This article was inspired by All About Birds: What Is the Essence of Iridescence? Ask a Hummingbird.

(credits are in the captions, click the links to see the originals)

Birds of State

Bald Eagle, the national bird of the United States (photo from Wikimedia Commons)

4 July 2023

Ever since we became a group of united states on 4 July 1776 we’ve grappled with the interplay of national versus state laws and culture. We even have national and state birds.

The bald eagle takes center stage today on the Fourth of July but our national bird is celebrated all year long. Meanwhile state birds are rarely mentioned. This map from VividMaps shows who they are, though Alaska’s willow ptarmigan and Hawaii’s nene are not pictured.

State Birds of the Contiguous US (image embedded from VividMaps via Reddit user Epicallytossed)

Many states have designated the same bird:

  • 7 states chose northern cardinals from Illinois to North Carolina
  • 6 states chose western meadowlarks from Oregon to Kansas
  • 5 states chose northern mockingbirds from Texas to Tennessee to Florida.

Half the states have unique birds including:

  • Pennsylvania: Ruffed grouse
  • California: California quail
  • Oklahoma: Scissor-tailed flycatcher
  • Maryland: Baltimore oriole
  • South Dakota: ring-necked pheasant (imported from Eurasia)
  • … and 20 more states

Why isn’t the peregrine falcon pictured for Idaho? The peregrine is Idaho’s State Raptor. So there are more than 51 Birds of State in the U.S.

See the list of state birds here.

(photo from Wikimedia Commons, map embedded from VividMaps, click on the captions to see the originals)

Humans Are Changing the Tilt of the Earth

Windmill pumping groundwater in Texas (photo from Wikimedia Commons)

19 June 2023

Compared to the size of our planet we humans aren’t particularly large but with billions of us pumping groundwater we have changed the tilt of the Earth. Slightly.

The angle of Earth’s axial tilt varies over a period of 26,000 years (precession) from 22.1 to 24.5 degrees, but within that it wobbles due to sloshing liquids like molten lava, ocean currents, and massive air currents such as hurricanes.

This very short video shows the North Pole wandering as the axis wobbles.

video from

Earth’s spin axis wobbles, its North Pole tracing out a roughly 10-meter-wide circle every year or so. The center of this wobble also drifts over the long term; lately, it has been tilting in the direction of Iceland by about 9 centimeters per year. …

Now, scientists have found that a significant amount of the polar drift results from human activity: pumping groundwater for drinking and irrigation.

Science Magazine: Humanity’s groundwater pumping has altered Earth’s tilt

Local water abundance, on the surface and underground, changes a region’s gravitational pull. This principle was used by the GRACE and GRACE-FO satellites as they rode the “hills” and “valleys” of gravity and recorded the presence and absence of groundwater.

To find out what affected Earth’s axial tilt, Clark R. Wilson at the University of Texas at Austin and his colleagues built a model of polar wander factoring in all the sloshing over time, including changes to surface water. But the model was missing something.

When the researchers also put in 2150 gigatons of groundwater that hydrologic models estimate were pumped between 1993 and 2010, the predicted polar motion aligned much more closely with observations. Wilson and his colleagues conclude that the redistribution of that water weight to the world’s oceans has caused Earth’s poles to shift nearly 80 centimeters during that time, reported Thursday in Geophysical Research Letters.

Science Magazine: Humanity’s groundwater pumping has altered Earth’s tilt

The GRACE satellites detected groundwater changes that produced this map. Notice how groundwater dropped in the U.S. Southeast and the Central Valley of California.

NASA GRACE data shows trends in global groundwater storage, 2003-2013 (map from NASA)

How did we pump so much groundwater? We used machines like these.

Groundwater pumping station at water facility (photo from Wikimedia Commons)

Watch the groundwater come and go in India 2002-2008 in this NASA video. (Click on the image to access the video.)

Groundwater depletion in India (video from NASA Goddard Space Flight Center)

Who knew that we could make the planet move!? 80 cm (31.5″) in just 17 years.

(photos from Wikimedia Commons, maps from NASA, click on the captions to see the originals)

Bear Trashes Truck

A bear wanted to get in this vehicle, California, 2016 (photo from Wikimedia Commons)

8 June 2023

Just because black bears don’t have thumbs doesn’t mean they can’t get into cars and trucks. If there’s food inside a vehicle they have a big incentive to open it, even if it means breaking the glass and bending metal, as shown above in California.

This week in Evergreen, Colorado a bear smelled dog food inside a truck in a driveway. Since the truck was unlocked he didn’t have to break the windows and doors to get in.

See what happened next in this tweet from Colorado Parks and Wildlife — Northeast Region (@CPW_NE).

(photo from Wikimedia Commons, tweet embedded from @CPW_NE)

Those Bird Codes

Blackpoll warbler gleaning insects from a boxelder (photo by Chuck Tague)
Blackpoll warbler gleaning insects from a boxelder (photo by Chuck Tague)

25 May 2023

Call me crazy. Or maybe old-fashioned.

Whenever I go birding I make a list — on paper — of the birds I see using the four-letter code for each species. When I get home I type the paper list into eBird. This paper list became this checklist.

Why don’t I just enter the birds directly into the eBird app on my phone? Unfortunately I learned long ago that if I look at my phone in the woods I start to read email, respond to text messages, check the news … and suddenly I’m not birding anymore and I’ve got a whole new set of Things To Do that I didn’t need to trouble with yet. So to keep myself focused I write a paper list.

The codes are easy to remember (see the rules here) except where the rules resolve to the same thing for two or more birds. The overlap codes are the ones I forget:

  • Bay-breasted warbler (should be BBWA, I wrote BAYB)
  • Blackpoll warbler (should be BLPW, I wrote BLKPOLL) and
  • Blackburnian warbler (should be BLBW, I wrote BLKBUR).

I remembered these, though:

  • BAOR = Baltimore oriole
  • CHSP = Chipping sparrow
  • MAWA = Magnolia warbler

My list should have been:

A few of the birds seen or heard in Frick Park on 18 May 2023

Where did the codes come from? If you’ve read this far you might be curious.

(photo by Kate St. John)