Hundreds of millions of tons of single-use plastic ends up in landfills every year, and even the small percentage of plastic that gets recycled can’t last forever. But our group of materials scientists has developed a new method for creating and deconstructing polymers that could lead to more easily recycled plastics – ones that don’t require you to carefully sort out all your recycling on trash day.

In the century since their conception, people have come to understand the enormous impacts – beneficial as well as detrimental – plastics have on human lives and the environment. As a group of polymer scientists dedicated to inventing sustainable solutions for real-world problems, we set out to tackle this issue by rethinking the way polymers are designed and making plastics with recyclability built right in.

Why use plastics, anyway?

Everyday items including milk jugs, grocery bags, takeout containers and even ropes are made from a class of polymers called polyolefins. Polyolefins make up around half of the plastics produced and disposed of every year.

These polymers are used in plastics commonly labeled as HDPE, LLDPE or PP, or by their recycling codes #2, #4 and #5, respectively. These plastics are incredibly durable because the chemical bonds that make them up are extremely stable. But in a world set up for single-use consumption, this is no longer a design feature but rather a design flaw.

Imagine if half of the plastics used today were recyclable by twice as many processes as they are now. While that wouldn’t get the recycling rate to 100%, a jump from single digits – currently around 9% – to double digits would make a big dent in the plastics produced, the plastics accumulated in the environment and their capacity for recycling and reuse.

Recycling methods we already have

Even the plastics that make it to a recycling facility can’t be reused in exactly the same way they were used before – the recycling process degrades the material, so it loses utility and value. Instead of making a plastic cup that is downgraded each time it gets recycled, manufacturers could potentially make plastics once, collect them and reuse them on and on.

Conventional recycling requires careful sorting of all the collected materials, which can be hard with so many different plastics. Here in the U.S., collection happens mainly through single stream recycling – everything from metal cans, glass bottles, cardboard boxes and plastic cups end up in the same bin. Separating paper from metal doesn’t require complex technology, but sorting a polypropylene container from a polyethylene milk jug is hard to do without the occasional mistake.

When two different plastics are mixed together during recycling, their useful properties are hugely reduced – to the point of making them useless.

But say you can recycle one of these plastics by a different method, so it doesn’t end up contaminating the recycling stream. When we mixed samples of polypropylene with a polymer we made, we were still able to depolymerize – or break down the material – and regain our building blocks without chemically affecting the polypropylene. This indicated that a contaminated waste stream could still recover its value, and the material in it could go on to be recycled, either mechanically or chemically.

Plastics we need − but more recyclable

In a study published in October 2023, our team developed a series of polymers with only two simple building blocks – one soft polymer and one hard polymer – that mimicked polyolefins but could also be chemically recycled.

Connecting two different polymers together multiple times until they form a single, long molecule creates what’s called a multiblock polymer. Just by adjusting how much of each polymer type goes into the multiblock polymer, our team created a wide range of materials with properties that spanned across polyolefin types. But creating these multiblock polymers is easier said than done.

To link these hard and soft polymers, we adapted a technique that had previously been used only on very small molecules. This method is improved relative to traditional methods of making polymers in a step-by-step fashion, developed in the 1920s, where the reactive groups on the end of the molecules need to be exactly matched.

In our method, the reactive groups are now the same as each other, meaning we didn’t have to worry about pairing the ends of each building block to make polymers that can compete with the polyolefins we already use. Using the same strategy, applied in reverse by adding hydrogen, we could disconnect the polymers back into their building blocks and easily separate them to use again.

With an almost twofold increase in annual plastic use projected through 2050, the complexity and quantity of plastic recycling will only increase. It’s an important consideration when designing new materials and products.

Using just two building blocks to make plastics that have a huge variety of properties can go a long way toward reducing and streamlining the number of different plastics used to make the products we need. Instead of needing one plastic to make something pliable, another for something stiff, and a third, fourth and fifth for properties in between, we could control the behavior of plastics by just changing how much of each building block is there.

Although we’re still in the process of answering some big questions about these polymers, we believe this work is a step in the right direction toward more sustainable plastics.

We were able to create materials that mimic the properties of plastics the world relies on, and our sights are now set on creating plastic compositions that you couldn’t with existing methods.

Katherine Harry, PhD Student in Chemistry, Colorado State University and Emma Rettner, PhD Candidate in Materials Science and Engineering, Colorado State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Postpartum depression can affect anyone, and it often sneaks in quietly, like a shadow in the corners of a new mother’s life. It presents significant challenges for around 1 in 7 new mothers, affecting their emotional well-being and overall quality of life and that of the newborn.

Many – if not most – women experience the “baby blues,” or generalized feelings of sadness, worry, unhappiness and exhaustion, in the initial days after giving birth. In most cases, these mood changes are resolved in the first two weeks after having a baby. In contrast, the symptoms of postpartum depression endure for more extended periods, sometimes lingering for up to three years.

The symptoms can also start during pregnancy. Research shows that more than half of women who experience depression symptoms during pregnancy will develop postpartum depression too.

A much more rare and severe psychiatric disorder following delivery is called postpartum psychosis. Its onset is rapid and severe, with hallucinations, delusions and emotional distress, along with bizarre and sometimes dangerous behaviors. About 1 or 2 in 1,000 women experience postpartum psychosis after giving birth.

We are a clinical nurse specialist and a licensed mental health counselor, and together we have over 45 years of experience as educators and clinicians.

With proper awareness, education and intervention, perinatal mood disorders are nearly 100% treatable. We want women to realize that they are not alone, they are not to blame, and with help they can be well again.

Crying, sadness and lack of bonding

Following pregnancy, many women experience normal changes that can mimic symptoms of depression, such as sadness, worry and exhaustion. The transition to motherhood, particularly with a new baby in the home, can be overwhelming. However, it’s essential to distinguish between these common adjustments and more concerning signs of depression.

If you or someone you know finds themselves experiencing any of the following symptoms persistently for over two weeks after giving birth, it’s crucial they reach out to their doctor, nurse or midwife. Here are some of the most-reported symptoms of postpartum depression:

• Lack of bonding and feeling disconnected from the baby or experiencing a lack of interest in them.
• Restlessness or moodiness and feeling unusually agitated or irritable.
• Persistent feelings of sadness, hopelessness or being overwhelmed.
• Experiencing physical symptoms such as persistent headaches, other body aches and pains or digestive issues that don’t resolve.
• A profound lack of energy or motivation, making daily tasks feel daunting.
• Significant changes in appetite and either eating too little or too much.
• Disturbed sleep patterns, such as sleeping too much or too little, even when given the opportunity to rest.
• Difficulty concentrating or making decisions, or experiencing memory problems.
• Overwhelming feelings of guilt, worthlessness or inadequacy as a mother.
• A notable decline in interest or pleasure in activities previously enjoyed.
• Isolating from friends and family, avoiding social interactions.
• Thoughts of harming the baby or themselves. These should be taken extremely seriously and warrant immediate attention.

Some risk factors associated with higher likelihood of postpartum depression include life stress, depression history, maternal anxiety, lack of social support, infrequent exercise, unintended pregnancy and intimate partner violence.

Real-life examples

People dealing with depression not only have to manage their symptoms but may also face the stigma and discrimination that these conditions often bring. There is an expectation that new parents will be happy after delivery. Sadness, stigma, shame or guilt greatly affects a person’s willingness to seek help. Studies show that many people opt not to seek treatment to avoid being perceived as unfit parents by health care providers or family.

As a nurse and a mom who has experienced postpartum depression, I (Nicole Lynch) frequently share my story with others. Years ago, another mom shared with me how helpful it was to hear that she wasn’t alone. Knowing that other women – dedicated parents who love their children – can feel this way and that things can get better gave her hope.

Throughout my career, I (Shannon Pickett) have worked with several mothers and prospective parents who have struggled with postpartum depression. For instance, I worked with one woman for several years about her anxiety and her struggle to conceive. After years of trying, she finally became pregnant. Both she and her husband were overjoyed and could not wait to become parents.

The pregnancy went smoothly and there were no complications. She had never shown any signs of depression previously, but once the baby was born, that changed. My client had trouble bonding with the baby and did not want to hold or console her new son when he needed soothing.

Her husband would often step in to comfort the infant and would ask my client, “What is wrong with you?” It caused frustration within their marriage because the father felt as though he was doing the caregiving alone and that my client was withdrawn. She had planned to take a break from therapy for a bit after the baby was born, but her husband encouraged her to reach out to schedule an appointment.

I could tell right away that she was struggling with postpartum depression. She barely smiled, had difficulty engaging in and concentrating on our conversation and cried throughout most of the session.

We talked a lot about the guilt she felt over not wanting to be around her son or hold him, even though she had fought for so long to become a mother. After receiving a proper diagnosis and starting an antidepressant medication, my client was able to recover and bond with her son. The medication did take a few weeks to get into her system, so the results were not instant. Maintaining her sessions and using her support system were important for her recovery as well.

Heightened risk

While postpartum depression can affect anyone regardless of their socioeconomic status or their background, some women affected by social inequalities have increased risk of many common postpartum mental disorders and their adverse consequences.

One study found that new mothers with low incomes, those who had not earned a college degree, were unmarried or were unemployed were 11 times more likely than women with no risk factors to have clinically elevated depression scores three months after having a baby.

Inadequate support

The Centers for Disease Control and Prevention estimates that about 20% of pregnant women were not asked about depression during a prenatal visit, and more than half of women with postpartum depression remain untreated for their symptoms.

What’s worse, there is a lack of access to mental health services for women after delivery. Many promising treatments are underexplored, especially in scientific studies. While more people are talking about postpartum depression, there is still stigma around seeking help.

A new medication offers hope

It’s vital to remember that postpartum depression is a treatable condition. Seeking help from health care professionals is a courageous and necessary step.

In August 2023, the Food and Drug Administration approved the first oral medication, Zurzuvae, specifically intended to treat severe depression after childbirth. It holds promise for addressing the complex array of symptoms associated with postpartum depression and offers newfound hope for affected mothers and their families.

If you are experiencing symptoms of postpartum depression, consider finding a therapist in your community for either telehealth or in-person sessions.

There are also postpartum support groups that meet in person and online.

Supportive therapies, including counseling, medication and lifestyle adjustments, can significantly alleviate symptoms and improve overall well-being. Early intervention is key to a faster and more complete recovery, ensuring that mothers can enjoy the precious moments with their baby and find fulfillment in motherhood.

Nicole Lynch, Clinical Nurse Specialist and Visiting Professor of Nursing, Purdue University and Shannon Pickett, Professor of Psychology and Licensed Mental Health Counselor, Purdue University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

In a recent talk about new ways to do college admissions, Secretary of Education Miguel Cardona spoke about his own experience taking a college course while still in high school. He was referring to dual enrollment – an increasingly common practice in which high school students take college courses, simultaneously earning high school and college credit.

A 2019 report showed that approximately 88% of U.S. high schools offered dual enrollment and approximately 34% of high school students in the U.S. are taking college courses. That represents an increase from 2010, when 82% of high schools offered dual enrollment and approximately 10% of high school students took college courses.

At the state level, there is evidence of dramatic growth. In Indiana, for example, 60% of high school students graduated with college credit in 2018, up from 39% in 2012.

As a higher education administrator who has been involved with dual enrollment in Boston’s public schools, I know there is strong evidence that dual enrollment programs make it more likely that students graduate from high school and earn a college degree.

How dual enrollment works

Dual enrollment programs may be known by different names, such as early college, concurrent enrollment, joint enrollment or dual credit programs. One study found the use of 97 different terms nationwide.

The courses are different from Advanced Placement and International Baccalaureate courses. While AP and IB courses cover college-level material, dual enrollment courses are college courses.

Students usually take these courses at their high schools, but they can also take them on a college campus, online or at another nearby high school. Some programs provide transportation to college campuses. The courses are offered in partnership with a college or university and taught by faculty from that college. Ideally, courses are offered during the standard high school day.

Academic and financial benefits

The North Carolina Career and College Promise dual enrollment program found that students in the program were 2% more likely to graduate from high school and 9% more likely to enroll in college compared with similar students who did not take dual enrollment courses.

Dual enrollment programs also provide a practical way for students and their families to save time and money. Students are able to take college courses for free or at a discounted rate while still in high school instead of paying tuition for the classes during college. The programs often include books, materials and transportation. During the 2017-18 school year, 78% of dual enrollment programs at public schools received full or partial funding from the school, district or state. Additional funding came from families, students or some other entity such as foundations and donors.

However, equity gaps exist within dual enrollment programs. Recruitment efforts that do not target equity, a lack of qualified faculty, and certain eligibility requirements – such as minimum GPAs and standardized test scores – create barriers for some students. Even when dual enrollment programs are available at their high school, Black and Hispanic students participate at lower rates than their white and Asian classmates. In addition, students whose parents had earned at least a bachelor’s degree were much more likely to take these courses than students whose parents had not earned a high school diploma.

Recruitment tool for colleges

Many colleges have experienced declining enrollments as of late, and some experts predict a looming “enrollment cliff” that some schools won’t survive. Dual enrollment programs can benefit colleges by drawing more students to their campuses, where they often re-enroll after high school.

A recent study found that 60% of 18- and 19-year-old college students took dual enrollment courses at their college while in high school.

For community colleges, high school students in dual enrollment programs now make up close to 20% of their enrollments.

The American Association of Collegiate Registrars and Admissions Officers found in 2016 that 75% of colleges offering dual enrollment programs viewed them as an important form of recruitment.

However, the increased likelihood that a student will enroll in the college where they took dual enrollment courses in high school has raised concerns about “undermatching.” Undermatching is a phenomenon in which high school students don’t apply to a more selective college or university even though they have the ability. One study found that when dual enrollment students stay at a two-year college where they are undermatched – instead of transferring to a more selective school – they are 33% less likely to complete a bachelor’s degree.

Still, dual enrollment programs have proven to be both successful and popular in states across the country. If current trends continue, and states such as Massachusetts continue to push for increased funding for dual enrollment, programs will continue to grow in high schools, on college campuses and online.

The hope is that growth in dual enrollment will lead to more students graduating from college and being able to get better jobs and live longer, healthier lives.

Mary L. Churchill, Associate Dean of Strategic Partnerships and Community Engagement, Boston University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Why is space so dark despite all of the stars in the universe? – Nikhil, age 15, New Delhi

People have been asking why space is dark despite being filled with stars for so long that this question has a special name – Olbers’ paradox.

Astronomers estimate that there are about 200 billion trillion stars in the observable universe. And many of those stars are as bright or even brighter than our sun. So, why isn’t space filled with dazzling light?

I am an astronomer who studies stars and planets – including those outside our solar system – and their motion in space. The study of distant stars and planets helps astronomers like me understand why space is so dark.

You can listen to more articles from The Conversation, narrated by Noa, here.

You might guess it’s because a lot of the stars in the universe are very far away from Earth. Of course, it is true that the farther away a star is, the less bright it looks – a star 10 times farther away looks 100 times dimmer. But it turns out this isn’t the whole answer.

Imagine a bubble

Pretend, for a moment, that the universe is so old that the light from even the farthest stars has had time to reach Earth. In this imaginary scenario, all of the stars in the universe are not moving at all.

Picture a large bubble with Earth at the center. If the bubble were about 10 light years across, it would contain about a dozen stars. Of course, at several light years away, many of those stars would look pretty dim from Earth.

If you keep enlarging the bubble to 1,000 light years across, then to 1 million light years, and then 1 billion light years, the farthest stars in the bubble will look even more faint. But there would also be more and more stars inside the bigger and bigger bubble, all of them contributing light. Even though the farthest stars look dimmer and dimmer, there would be a lot more of them, and the whole night sky should look very bright.

It seems I’m back where I started, but I’m actually a little closer to the answer.

Age matters

In the imaginary bubble illustration, I asked you to imagine that the stars are not moving and that the universe is very old. But the universe is only about 13 billion years old.

Even though that’s an amazingly long time in human terms, it’s short in astronomical terms. It’s short enough that the light from stars more distant than about 13 billion light years hasn’t actually reached Earth yet. And so the actual bubble around Earth that contains all the stars we can see only extends out to about 13 billion light years from Earth.

There just are not enough stars in the bubble to fill every line of sight. Of course, if you look in some directions in the sky, you can see stars. If you look at other bits of the sky, you can’t see any stars. And that’s because, in those dark spots, the stars that could block your line of sight are so far away their light hasn’t reached Earth yet. As time passes, light from these more and more distant stars will have time to reach us.

The Doppler shift

You might ask whether the night sky will eventually light up completely. But that brings me back to the other thing I told you to imagine: that all of the stars are not moving. The universe is actually expanding, with the most distant galaxies moving away from Earth at nearly the speed of light.

Because the galaxies are moving away so fast, the light from their stars is pushed into colors the human eye can’t see. This effect is called the Doppler shift. So, even if it had enough time to reach you, you still couldn’t see the light from the most distant stars with your eyes. And the night sky would not be completely lit up.

If you wait even longer, eventually the stars will all burn out – stars like the sun last only about 10 billion years. Astronomers hypothesize that in the distant future – a thousand trillion years from now – the universe will go dark, inhabited by only stellar remnants like white dwarfs and black holes.

Even though our night sky isn’t completely filled with stars, we live in a very special time in the universe’s life, when we’re lucky enough to enjoy a rich and complex night sky, filled with light and dark.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to This email address is being protected from spambots. You need JavaScript enabled to view it.. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Brian Jackson, Associate Professor of Astronomy, Boise State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.