“Oxy” cleaners may make forensic tests, such as this one checking a shoeprint for blood, ineffective.

Criminal investigations begin with a search for clues. Teams of investigators arrive at a crime scene armed with special fact-finding gear. They look for standard evidence like fingerprints, footprints or blood at the scene of a crime.

But scientists recently discovered something troubling. Some new household cleansers can remove all traces of blood. If criminals simply use these products to clean up after themselves, police may have a hard time gathering evidence.

To get at particularly stubborn stains, like an accident from your pet, your parents may use one of these new products called “oxy” cleaners. These cleansers use oxygen and water to attack stains, including blood. Some of the ads claim to clean “over 101 stains on multiple surfaces.” That sounds good, but scientists have identified a downside to that much cleaning power.

The oxy cleaners even go beyond getting rid of visible stains. Usually detectives’ gear can find traces of blood that are invisible to the naked eye. But these oxy cleaners make even the invisible traces of blood unrecognizable to the most common blood-detecting tests.

The three standard tests for picking up blood rely on a protein in the blood called hemoglobin. This protein loves oxygen. In the body, it’s hemoglobin’s job to grab onto oxygen and carry it from the lungs to the rest of the body. But the new oxy cleaners flood a blood stain with a lot of oxygen. Once the protein gets its fill of oxygen, it won’t even bother to snatch oxygen from the investigators’ blood detecting tests. This means these tests will come up negative.

When you scrape your knee, a nurse, parent, or coach may rub it with hydrogen peroxide. Hydrogen peroxide contains hydrogen and oxygen and helps stop the bleeding. The chemical causes oxygen that looks like foam to rise to the surface of your cut. There, too, hemoglobin in your blood seeks the oxygen in the hydrogen peroxide.

Common blood detectors rely on the same kind of reaction between blood’s oxygen and hydrogen peroxide. The detectors contain hydrogen peroxide that reacts with hemoglobin in a blood stain. When hemoglobin grabs some oxygen, the blood detecting test gives a positive result. Depending on the chemical in the test, a positive result might glow or turn pink.

In the name of science, a group of researchers decided to test the oxy cleaners. The scientists made their own fake crime scene by using samples of their own blood to stain a couple pieces of cloth. The team put five drops of their own blood on a soft cotton cloth, some jeans and a towel.

Then, the researchers washed part of each cloth sample in “Neutrex,” an oxy cleanser. The team thought the oxygen in Neutrex would be released upon contact with water. The large amount of oxygen would cause the hemoglobin to work overtime. This would effectively clean up the blood, but also tire out the hemoglobin so that it wouldn’t react with the tests. The scientists also washed other samples of blood-stained cloths with a traditional cleaner. All the samples were then left to air dry.

The cleaners worked as the scientists suspected. The cloths washed without oxy cleaners looked clean, but the three tests still picked up the blood traces. But after an oxy wash, the other sample fabrics looked spotless to the naked eye, and also came up clean on the blood tests. The difference: The oxygen bath given to hemoglobin exposed to the oxy cleaners. After spending time in the presence of that much oxygen and trying to snatch it, the hemoglobin couldn’t react with the investigators’ tests.

Despite the study’s results, this cleaning possibility doesn’t mean that bloody crime scenes are a thing of the past. “People committing violent crimes often don’t have time to clean up; they leave a lot of stuff behind,” says Walter Rowe, a forensic scientist, someone who examines evidence in a legal case, at George Washington University in Washington, D.C.

Scientists have figured out that exposing portabella mushrooms to sunlight can boost the fungis’ vitamin D amounts.

Over the past few years the sun has gotten a bad rap. Too much sunshine can put you at risk for skin cancer. And an overdose of sun can also lead to nasty sunburns, or even heatstroke.

But the sun isn’t always bad for the body. Scientists have known for years that the sun is a great source of vitamin D. This vitamin naturally boosts the immune system, your body’s defense against disease. Now mushrooms bathed in ultraviolet (UV) light — like that from the sun — can help you get some of this valuable vitamin.

Each year there are more and more studies released that suggest if you want to be healthy, vitamin D is where it’s at. Vitamin D strengthens your heart and bones, and can prevent asthma and some forms of cancer and diabetes.

Some foods, like fish and eggs, are naturally brimming with the vitamin. And others, like milk and some cereals, are fortified with vitamin D. But you would need to consume a lot of milk and cereal to get your daily dose of vitamin D. Sunlight still reigns king as the best source for vitamin D.

Recently scientists have shown that specially treated mushrooms could give people a vitamin D boost. U.S. Department of Agriculture researchers in California treated portabella mushrooms to suntanning sessions of up to 18 minutes. The mushrooms didn’t develop a bronze glow or complain of heat stroke though. Instead each mushroom produced nearly 4 micrograms of vitamin D per gram of tissue. When white mushrooms were given similar sun treatments, these fungi boasted extra vitamin D, too. Now both kinds of vitamin-infused ‘shrooms are on the market. So if you like mushrooms, you could munch your way to a higher daily dose of Vitamin D.

Depending on a person’s age, people should get between 5 and 15 micrograms (or 200 to 600 international units) of vitamin D each day. Without these amounts, people are prone to get diseases like rickets, which causes distorted, soft bones. These numbers, though, are really just a minimum. Now some scientists suggest it’s better to get as much as five times the recommended vitamin D dose each day.

Having more foods with Vitamin D is a good thing, since there are also several factors that make it hard to get enough of the vitamin from just the sun.

One factor influencing elderly people’s vitamin D intake is that they often spend less time outdoors. Therefore, they need more vitamin D in their diet. And if you spend a lot of your time indoors, playing video games or on the computer, you may need extra vitamin D from your food, too.

Skin color and weight also help determine a person’s vitamin D needs. Darker skin filters out more of the sun’s UV light, so people with darker skin need more sun exposure to make necessary amounts of vitamin D. For unknown reasons, heavier people also need a greater amount of UV light to enable vitamin D production.

And latitude — how far north or south you live — can play a major role in the sun’s ability to help you get adequate vitamin D amounts. As you get farther away from the equator, the amount of UV-filtering atmosphere increases. This means that at higher, more northern latitudes, people get less UV rays. So, if you live in a state like Alaska, most of the year you can’t get enough sun to trigger the vitamin’s production by your skin.

Eating foods enriched with vitamin D or taking a daily vitamin may not be as satisfying as breaking out your bathing suit and lying in the sun. But the right foods and supplements can help keep you healthy until summer’s rays are here again.

Going Deeper:

Western white pine cones light up when seen through an infrared camera. Even under cloudy conditions, the cones run 15 degrees Celsius warmer than the surrounding needles.

Superman may have something in common with one kind of seed-eating bug. Both use special powers to zero in on a warm target. In the bug’s case, the target is dinner.

For humans, finding some Oreos or popcorn can be a challenge in a crowded supermarket. Now imagine how hard it must be for a tiny bug on the lookout for pine cone seeds. The insects have to search among many needles. And there aren’t any aisles with signs.

Recently scientists discovered that a bug that dines on pine cone seeds uses a special ability to seek them out. This insect finds its next meal by sensing the food’s temperature. All living things give off heat in the form of infrared light. While this kind of light is invisible to humans, scientists have found that the seed-eating bug is able to detect it.

When it grows cold outside this cone-loving bug shows up in people’s homes. This got bug scientists thinking. Perhaps the seed-eaters were creeping into homes looking for a warm place to catch some zzz’s. And if the bugs could sense the warmth in homes, maybe they could sense warm food, too.

Scientists know that some plants can generate heat. Skunk cabbages, for example, heat themselves and even melt the snow around them. So the bug scientists thought the seed bugs could be searching for cones that give off some heat.

The researchers took their theory, or idea, outdoors for a test. They brought along a special camera that gave them the ability to see warmth. Through this camera, heat showed up in shades of yellow and orange. When the scientists looked at the pine cones through the camera, the bugs’ food lit up. The trees looked as if they were covered in candles. “All we could think of was Christmas,” said Stephen Takács, the leader of the study and a scientist at Simon Fraser University in Burnaby, Canada. “We were just stunned.”

The researchers took the temperatures of different kinds of cones and needles during each season. It turned out the cones were always about 15 degrees Celsius warmer than the surrounding needles. That’s the difference between needing a light jacket and knowing it’s time to break out your shorts. The find was proof enough that the cones were warmer than their environment. Still, the team wanted to explore if the bugs were truly detecting the hotter food.

Seed-eating bugs armed with infrared detectors zero in on the glow of cones.

Photography Iisak Andreller; Thermography: Stephen Takács

The scientists hunkered down and watched the bugs search for food in the wild and in the lab. Sure enough, the insects had an obvious preference for cones that glowed especially bright from their warmth.

This is the first time scientists have found a seed-eater with a knack for detecting heat given off by its plant meal, Takács says. Scientists have started to wonder if other bugs have similar skills.

“We tend to focus on things humans can see, can observe easily” explains scientist Irene Terry of the University of Utah in Salt Lake City. Now scientists are learning that other things help insects find food, she says.

On the bugs’ bodies, researchers found sensors that seemed to be used to find the warm cones. The scientists tested this theory by painting over the sensors with silica paint. This kind of paint blocked the bugs’ sensors from detecting the heat. The team found that, once painted, the bugs no longer hunted for the “lit up” cones.

The scientists also peered inside the bugs’ nervous system, which responds to input from the senses. The researchers found a clear pathway from the sensors to the brain. This connection might be used to tell the bugs’ brains that hot food is directly ahead or, maybe, a little to the left.

Takács isn’t sure why the cones are warm. He thinks the cones may be hotter because bigger objects collect heat better than smaller objects. He says the warmth could also be produced from the energy generated during seed development.

While scientists continue to search for these answers we can be sure of at least one thing. These seed-eating bugs have the skills to find their next hot meal.

Going Deeper:

A little brown bat’s moldy white nose marks it as suffering from white-nose syndrome. The disease is killing hundreds of thousands of hibernating bats in the northeastern U.S. Scientists recently identified the mold, a form new to science, in a lab.

When you think of things that are white and fuzzy, usually you think of something cute or nice. But a newly discovered fuzzy, white mold may be making bats in the Northeast U.S. sick. The illness and mold strike during hibernation, bats’ long wintertime sleep.

The mold was first spotted by a cave explorer two years ago. The fuzzy fungus was growing on hibernating bats’ noses and wings. Bats with the mold often grew thin, weak and died. Scientists named this phenomenon “white-nose syndrome” after the mold found on the bats’ noses.

Since that first sighting, thousands of bats in the Northeast have died. Scientists now wonder if the mystery fungus may be the killer. Once the mold hits caves or mines where bats are hibernating, between 80 and 100 percent of the bats usually die, says Marianne Moore, a bat researcher at Boston University.

Northeastern bats hunt insects, including some that are pests. So a lack of bats “could be a huge problem,” Moore says.

Scientists still aren’t sure if the white fuzz is the killer. The mold may just attack bats when they are already sick and more likely to get other illnesses. But, identifying the fungus may help scientists find out if it’s the killer.

To figure out what the fungus was, scientists studied it in a lab. They took samples of the mold from sick bats. Then the scientists brought the samples to a lab, where they could grow and be compared to other molds.

At room temperature, the scientists’ efforts were thwarted — samples of this mystery mold wouldn’t develop. Frustrated, the scientists finally tried putting the samples in the refrigerator. This cooled the samples down to temperatures found in bat caves during the winter. Sure enough, when the lab samples were chilly, an unfamiliar form of mold began to grow. The scientists think it may be an entirely new species, or type, of mold or a new form of an existing species.

What’s unusual about the new mold is that it won’t survive in higher temperatures, says David Blehert of the U.S. Geological Survey’s National Wildlife Health Center in Madison, Wisc. He and colleagues were part of the study that tried to grow and identify the mold in the lab.

Human noses, for example, are way too warm for the fungus.

In hibernation, “a bat for all practical purposes is almost dead” says Blehert. The heart of an active bat beats hundreds of times per minute. This can drop as low as about four beats per minute during hibernation. And a bat’s body during this time chills to only a few degrees above the cave’s temperature. The cold temperature of bat caves in New England makes for a perfect home for the mold.

This is good news for bats that fly to the warm south in the winter or live in warm, dry places year-round. Their caves will be too warm to host the white fuzz.

But the sickness has already hammered at least six species of bats in the Northeast. Two of these bats are the little brown bat and the endangered Indiana bat.

Going Deeper: