Tag Archives: science explained

The Chemistry of Hair Coloring

Scientists Develop the First Significant Advance in Hair Dye in 50 Years by Kristen Philipkoski

Hair color is serious chemistry. Getting color into that hair shaft is no joke. That’s why Procter & Gamble employs 1,800 “beauty scientists” around the globe. I spoke to two of these beauty scientists this week who told me they have invented a kinder hair color, and that it marks the first significant advance in dye jobs in 50 years.
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Small, diffuse color molecules enter the hair, and while they’re inside, they oxidize and form a chemical reaction with a larger color molecule that’s already trapped in there. But the small molecules aren’t all that selective about who they get it on with, and they end up breaking some of the chemical bonds that hold hair together. That releases free radicals that make hair weaker and less able to resist things like aggressive brushing, blow-drying and ironing.
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So the beauty scientists came up with a whole new chemistry for getting the lightening molecules inside the hair. First, the new process works at a much lower pH. That makes it less alkaline, so it strips away much less of the lipid coating.

Science Summary: Photosynthesis

Seed’s latest cribsheet, a one page summary of Photosynthesis:

Through the process of photosynthesis, plants, algae, and bacteria use sunlight to convert water and carbon dioxide into the oxygen and food that sustain much of life on Earth. This Cribsheet covers the basics of photosynthesis: where it happens, how light is used in the process, and why we think photosynthesis may have triggered the rise of complex life. In addition, we tell you why plants are green and how photosynthesis could temper climate change—if rainforests and oceanic ecosystems aren’t destroyed.

Related: String Theory Explained in One Page – Physics Concepts in 60 Seconds – Chemistry of Common Items

Female Sharks Can Reproduce Alone

Female Sharks Can Reproduce Alone, Researchers Find

A team of American and Irish researchers have discovered that some female sharks can reproduce without having sex, the first time that scientists have found the unusual capacity in such an ancient vertebrate species. The[y] report that sharks can reproduce asexually through the process known as parthenogenesis
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Though the three females had been caught before they reached sexual maturity and held in captivity for more than three years, researchers initially thought one had stored sperm from a male shark before fertilizing an egg. But the team — which included scientists at Nova Southeastern University in Florida, Queen’s University Belfast and the zoo — determined that the baby shark’s genetic makeup perfectly matched one of the females in the tank, with no sign of a male parent.

Mahmood Shivji — Nova Southeastern’s Guy Harvey Research Institute director and one of the paper’s authors — said that he and his colleagues determined that a byproduct formed when sharks produce eggs, known as a sister polar body, had fused with an unfertilized egg to produce the baby shark, whose DNA had only half as much genetic variability as the mother.

Related: Sex and the Seahorse – 50 New Species Found in Indonesia Reefs – Arctic Sharks – Bdelloid Rotifers Abandoned Sex 100 Million Years Ago

Why do We Sleep?

Study puts us one step closer to understanding the purpose of sleep:

Sleep remains one of the big mysteries in biology. All animals sleep, and people who are deprived of sleep suffer physically, emotionally and intellectually. But nobody knows how sleep restores the brain.
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Although an electronic power-napper sounds like a product whose time has come, Tononi is chasing a larger quarry: learning why sleep is necessary in the first place. If all animals sleep, he says, it must play a critical role in survival, but that role remains elusive.

Based on the fact that sleep seems to “consolidate” memories, many neuroscientists believe that sleeping lets us rehearse the day’s events.

Tononi agrees that sleep improves memory, but he thinks this happens through a different process, one that involves a reduction in brain overload. During sleep, he suggests, the synapses (connections between nerve cells) that were formed by the day’s learning can relax a little.

Researchers Learn What Sparks Plant Growth

Researchers Learn What Sparks Plant Growth:

“How do organisms decide when to grow and when to stop growing? These questions are especially important in plants because they are rooted in the ground and must alter their shape and size in response to their local environment. Thus, it’s a question of survival,” added Chory. “It took us 10 years to develop the tools to ask the question. It is very satisfying for me to see the results.”
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“It’s been a matter of some debate for a very long time if one of these tissue layers controls plant growth or if all three layers have to work together,” Chory said. “Our paper shows very clearly that the epidermis is in control—in both driving and restricting growth. In addition, our studies show that the cells in the epidermis “talk” to the cells in the inner layers, communicating that they too should expand.”
March Flowers

In January we had a long stretch of warm weather. Shoots for early blooming flowers sprouted in my front yard. Then we had about 6 weeks of winter weather. I was wondering how the flowers would do (they do fine with a few days of freezing weather after sprouting – since they have evolved to bloom early). They did fine, photo above (by John Hunter, March 11th).

Related: More Nutritious Wheat – What Are Flowers For?

What is an Extremophile?

What is an Extremophile?

An extremophile is an organism that thrives under “extreme” conditions. The term frequently refers to prokaryotes and is sometimes used interchangeably with Archaea.
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The term extremophile is relatively anthropocentric. We judge habitats based on what would be considered “extreme” for human existence. Many organisms, for example, consider oxygen to be poisonous.

The site includes interesting photos and details on all sorts of extremophiles: Anaerobe (don’t require oxygen) – Endolith (live inside rocks) – Thermophile (enjoy over 40 °C).

Related: Types of Microbes – Life Untouched by the Sun

Spider Thread

Spider hanging by its thread

Why a spider hanging from a thread does not rotate

The extraordinary properties of spider’s thread are like a blessing for researchers working on polymers. However, the amazing twisting properties it displays are still not very well understood. How can one explain the fact that a spider suspended by a thread remains completely motionless, instead of rotating like a climber does at the end of a rope?
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Spider’s thread, on the other hand, is very efficient at absorbing oscillations, regardless of air resistance, and retains its twisting properties during the experiments. It also returns to its exact original shape. Certain alloys, such as Nitinol, possess similar properties but must be heated to 90° to return to their original shape.

The amazing properties of spider’s thread have been known for several years: its ductility, strength and hardness surpass those of the most complex synthetics fibers

See more blog posts on life science, biology, etc. and more posts of interest to students and everyone interesting in learning about science.

How do antibiotics kill bacteria?

How do antibiotics kill bacterial cells but not human cells? (pointy haired bosses (phb) at Scientific American broke the link so I removed it – see links in comments below that are not broken by phb behavior)

Most bacteria produce a cell wall that is composed partly of a macromolecule called peptidoglycan, itself made up of amino sugars and short peptides. Human cells do not make or need peptidoglycan. Penicillin, one of the first antibiotics to be used widely, prevents the final cross-linking step, or transpeptidation, in assembly of this macromolecule. The result is a very fragile cell wall that bursts, killing the bacterium.

Read more blog posts on antibiotics and on health care.