Bacteria

Written by Science Knowledge on 9:07 PM

Your most successful cohabitants are bacteria—microscopic organisms that have only a single cell to their names. Their numbers are overwhelming— you’ll find millions in a drop of saliva and billions in a gram of garden soil. And despite the fact that you’ll never see one (at least not without help from a seriously powerful microscope), they’re easily the world’s most populous life-form. As microbiologists like to say, we are the minority on planet Earth.

Up close, bacteria have a variety of shapes. They may look like tiny spheres, spirals, or—most commonly—stubby rods, like the happy family of E. coli

Bacteria of all kinds cover just about every livable surface in the world around you. In fact, they thrive in a lot of places you probably don’t want them, such as your kitchen silverware. But the part that you really don’t want to think about is that you’re never far from their favorite home—you.

Bacteria colonize your mouth, throat, and eyes. Entire civilizations of exotic life-forms reside on your skin. But most of the bacteria in your body live in the winding passages of your digestive tract. In fact, bacteriologists say that the number of bacteria in your intestines is 10 times greater than the total number of cells that make up your entire body. (Fortunately, bacterial cells are quite a bit smaller than the other cells in your body.) This fact has led some sharp-witted scientists to ask if our bodies are really designed for us, or if we’re just around to serve as a giant luxury hotel for the care and feeding of bacteria.

Bacteria are responsible for many infamous diseases, including anthrax, tetanus, tuberculosis, the Black Plague, and (on a more embarrassing note) syphilis and gonorrhea. Bacteria are also behind most food-borne diseases, including one of the world’s most studied pathogens, E. coli.

Next time you look at your weight on the scale and see a number that’s a shade too high for your liking, remind yourself that bacteria account for a solid 4 pounds of the total.

Source of Information : Oreilly - Your Body Missing Manual

Is There a Link Between Vaccines and Autism?

Written by Science Knowledge on 9:03 PM

It’s a nightmare scenario for concerned parents—a routine vaccination triggers a lifelong developmental disorder that can impair communication and social function. But is it a genuine risk, or is it just the wild paranoia of conspiracy theorists with tinfoil hats?

As any self-respecting scientist will tell you, absolutely anything is possible. What seems stark-raving bonkers today just might become the cornerstone of new discoveries tomorrow. That said, scientists have spent a solid decade searching for a link between vaccines and autism, and to date, a great deal of peer-reviewed research has conclusively found no relationship. The removal of a much-feared mercury additive from vaccines has had no effect on rates of autism. And promising new lines of research suggest that the roots of autism may be set by birth, and possibly influenced by events in the womb.

Today most scientists attribute the rise in autism rates to increased reporting—in other words, now that the disorder has a name and a clear identity, parents and doctors are quicker to spot it. One thing is clear: While avoiding vaccines is unlikely to protect against autism, it does roll the dice on an unsettling collection of childhood illnesses. Many of these diseases can kill or cause debilitating effects that last a lifetime—a fact that has slipped out of modern consciousness as the last people who faced those diseases die of old age.

Furthermore, it’s important to realize that parents who refuse to vaccinate their children have it relatively easy today, because the most likely avenues of infection—other people—are themselves mostly immunized. But there comes a critical point where a community has enough non-immunized people to sustain a deadly infection and pass it around. In Britain, where the immunization rate has recently dipped to 85 percent, a young boy who had not been given the measles-mumps-rubella vaccine achieved a dubious distinction: He became the first British citizen to die of measles in 14 years.

Source of Information : Oreilly - Your Body Missing Manual

10 Unsolved Mysteries -> Can We Continuously Monitor Our Own Chemistry?

Written by Science Knowledge on 8:59 PM

Increasingly, chemists do not want to just make molecules but also to communicate with them: to make chemistry an information technology that will interface with anything from living cells to conventional computers and fiber-optic telecommunications. In part, it is an old idea: biosensors in which chemical reactions are used to report on concentrations of glucose in the blood date back to the 1960s, although only recently has their use for monitoring diabetes been cheap, portable and widespread. Chemical sensing could have countless applications—to detect contaminants in food and water at very low
concentrations, for instance, or to monitor pollutants and trace gases present in the atmosphere. Faster, cheaper, more sensitive and more ubiquitous chemical sensing would yield progress in all of those areas.

It is in biomedicine, though, that new kinds of chemical sensors would have the most dramatic potential. For instance, some of the products of cancer genes circulate in the bloodstream long before the condition becomes apparent to regular clinical tests. Detecting these chemicals early might make prognoses more timely and accurate. Rapid genomic profiling would enable drug regimens to be tailored to individual patients, thereby reducing risks of side effects and allowing some medicines to be used that today are hampered by their dangers to a genetic minority.

Some chemists foresee continuous, unobtrusive monitoring of all manner of biochemical markers of health and disease, perhaps providing real-time information to surgeons during operations or to automated systems for delivering remedial drug treatments. This futuristic vision depends on developing chemical methods for selectively sensing particular substances and signaling about them even when the targets occur in only very low concentrations.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> Can We Devise New Ways to Create Drugs?

Written by Science Knowledge on 8:55 PM

The core business of chemistry is a practical, creative one: making molecules, a key to creating everything from new materials to new antibiotics that can outstrip the rise of resistant bacteria.

In the 1990s one big hope was combinatorial chemistry, in which thousands of new molecules are made by a random assembly of building blocks and then screened to identify those that do a job well. Once hailed as the future of medicinal chemistry, “combi-chem” fell from favor because it produced little of any use.

But combinatorial chemistry could enjoy a brighter second phase. It seems likely to work only if you can make a wide enough range of molecules and find good ways of picking out the minuscule amounts of successful ones. Biotechnology might help here—for example, each molecule could be linked to a DNA-based “bar code” that both identifies it and aids its extraction. Or researchers can progressively refine the library of candidate molecules by using a kind of Darwinian evolution in the test tube. They can encode potential protein-based drug molecules in DNA and then use error-prone replication to generate new variants of the successful ones, thereby finding improvements with each round of replication and selection.

Other new techniques draw on nature’s mastery at uniting molecular fragments in prescribed arrangements. Proteins, for example, have a precise sequence of amino acids because that sequence is spelled out by the genes that encode the proteins. Using this model, future chemists might program molecules to assemble autonomously. The approach has the advantage of being “green” in that it reduces the unwanted by-products typical of traditional chemical manufacturing and the associated waste of energy and materials.

David Liu of Harvard University and his co-workers are pursuing this approach. They tagged the building blocks with short DNA strands that program the linker’s structure. They also created a molecule that walks along that DNA, reading its codes and sequentially attaching small molecules to the building block to make the linker—a process analogous to protein synthesis in cells. Liu’s method could be a handy way to tailor new drugs. “Many molecular life scientists believe that macromolecules will play an increasingly central, if not dominant, role in the future of therapeutics,” Liu says.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> What Is the Best Way to Make Biofuels?

Written by Science Knowledge on 8:41 PM

Instead of making fuels by capturing the rays of the sun, how about we let plants store the sun’s energy for us and then turn plant matter into fuels? Biofuels such as ethanol made from corn and biodiesel made from seeds have already found a place in the energy markets, but they threaten to displace food crops, particularly in developing countries where selling biofuels abroad can be more lucrative than feeding people at home. The numbers are daunting: meeting current oil demand would mean requisitioning huge areas of arable land.

Turning food into energy, then, may not be the best approach. One answer could be to exploit other, less vital forms of biomass. The U.S. produces enough agricultural and forest residue to supply nearly a third of the annual consumption of gasoline and diesel for transportation.

Converting this low-grade biomass into fuel requires breaking down hardy molecules such as lignin and cellulose the main building blocks of plants. Chemists already know how to do that, but the existing methods tend to be too expensive, inefficient or difficult to scale up for the enormous quantities of fuel that the economy needs.

One of the challenges of breaking down lignin—cracking open the carbon-oxygen bonds that link “aromatic,” or benzenetype, rings of carbon atoms—was recently met by John Hartwig and Alexey Sergeev, both at the University of Illinois. They found a nickel-based catalyst able to do it. Hartwig points out that if biomass is to supply nonfossil-fuel chemical feedstocks as well as fuels, chemists will also need to extract aromatic compounds (those having a backbone of aromatic rings) from it. Lignin is the only major potential source of such aromatics in biomass.

To be practical, such conversion of biomass will, moreover, need to work with mostly solid biomass and convert it into liquid fuels for easy transportation along pipelines. Liquefaction would need to happen on-site, where the plant is harvested. One of the difficulties for catalytic conversion is the extreme impurity of the raw material—classical chemical synthesis does not usually deal with messy materials such as wood. “There’s no consensus on how all this will be done in the end,” Hartwig says. What is certain is that an awful lot of any solution lies with the chemistry, especially with finding the right catalysts. “Almost every industrial reaction on a large scale has a catalyst associated” with it, Hartwig points out.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> What Is the Best Way to Make Biofuels?

Written by Science Knowledge on 11:40 PM

Instead of making fuels by capturing the rays of the sun, how about we let plants store the sun’s energy for us and then turn plant matter into fuels? Biofuels such as ethanol made from corn and biodiesel made from seeds have already found a place in the energy markets, but they threaten to displace food crops, particularly in developing countries where selling biofuels abroad can be more lucrative than feeding people at home. The numbers are daunting: meeting current oil demand would mean requisitioning huge areas of arable land.

Turning food into energy, then, may not be the best approach. One answer could be to exploit other, less vital forms of biomass. The U.S. produces enough agricultural and forest residue to supply nearly a third of the annual consumption of gasoline and diesel for transportation.

Converting this low-grade biomass into fuel requires breaking down hardy molecules such as lignin and cellulose, the main building blocks of plants. Chemists already know how to do that, but the existing methods tend to be too expensive, inefficient or difficult to scale up for the enormous quantities of fuel that the economy needs.

One of the challenges of breaking down lignin—cracking open the carbon-oxygen bonds that link “aromatic,” or benzenetype, rings of carbon atoms—was recently met by John Hartwig and Alexey Sergeev, both at the University of Illinois. They found a nickel-based catalyst able to do it. Hartwig points out that if biomass is to supply nonfossil-fuel chemical feedstocks as well as fuels, chemists will also need to extract aromatic compounds (those having a backbone of aromatic rings) from it. Lignin is the only major potential source of such aromatics in biomass.

To be practical, such conversion of biomass will, moreover, need to work with mostly solid biomass and convert it into liquid fuels for easy transportation along pipelines. Liquefaction would need to happen on-site, where the plant is harvested. One of the difficulties for catalytic conversion is the extreme impurity of the raw material—classical chemical synthesis does not usually deal with messy materials such as wood. “There’s no consensus on how all this will be done in the end,” Hartwig says. What is certain is that an awful lot of any solution lies with the chemistry, especially with finding the right catalysts. “Almost every industrial reaction on a large scale has a catalyst associated” with it, Hartwig points out.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> How Do We Tap More Solar Energy?

Written by Science Knowledge on 11:26 PM

With every sunrise comes a reminder that we currently tap only a pitiful fraction of the vast clean-energy resource that is the sun. The main problem is cost: the expense of conventional photovoltaic panels made of silicon still restricts their use. Yet life on Earth, almost all of which is ultimately solar-powered by photosynthesis, shows that solar cells do not have to be terribly efficient if, like leaves, they can be made abundantly and cheaply enough.


“One of the holy grails of solar-energy research is using sunlight to produce fuels,”
says Devens Gust of Arizona State University. The easiest way to make fuel from solar energy is to split water to produce hydrogen and oxygen gas. Nathan S. Lewis and his collaborators at Caltech are developing an artificial leaf that would do just that [see illustration on opposite page] using silicon nanowires.

Earlier this year Daniel Nocera of the Massachusetts Institute of Technology and his co-workers unveiled a siliconbased siliconbased membrane in which a cobaltbased photocatalyst does the water splitting. Nocera estimates that a gallon of water would provide enough fuel to power a home in developing countries for a day. “Our goal is to make each home its own power station,” he says.

Splitting water with catalysts is still tough. “Cobalt catalysts such as the one that Nocera uses and newly discovered catalysts based on other common metals are promising,” Gust says, but no one has yet found an ideal inexpensive catalyst. “We don’t know how the natural photosynthetic catalyst, which is based on four manganese atoms and a calcium atom, works,” Gust adds.

Gust and his colleagues have been looking into making molecular assemblies for artificial photosynthesis that more closely mimic their biological inspiration, and his team has managed to synthesize some of the elements that could go into such an assembly. Still, a lot more work is needed on this front. Organic molecules such as the ones nature uses tend to break down quickly. Whereas plants continually produce new proteins to replace broken ones, artificial leaves do not (yet) have the full chemicalsynthesis machinery of a living cell at their disposal.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> How Do We Tap More Solar Energy?

Written by Science Knowledge on 3:11 AM

With every sunrise comes a reminder that we currently tap only a pitiful fraction of the vast clean-energy resource that is the sun. The main problem is cost: the expense of conventional photovoltaic panels made of silicon still restricts their use. Yet life on Earth, almost all of which is ultimately solar-powered by photosynthesis, shows that solar cells do not have to be terribly efficient if, like leaves, they can be made abundantly and cheaply enough.
“One of the holy grails of solar-energy research is using sunlight to produce fuels,” says Devens Gust of Arizona State University. The easiest way to make fuel from solar energy is to split water to produce hydrogen and oxygen gas. Nathan S. Lewis and his collaborators at Caltech are developing an artificial leaf that would do just using silicon nanowires.

Earlier this year Daniel Nocera of the Massachusetts Institute of Technology and his co-workers unveiled a siliconbased membrane in which a cobaltbased photocatalyst does the water splitting. Nocera estimates that a gallon of water would provide enough fuel to power a home in developing countries for a day. “Our goal is to make each home its own power station,” he says.

Splitting water with catalysts is still tough. “Cobalt catalysts such as the one that Nocera uses and newly discovered catalysts based on other common metals are promising,” Gust says, but no one has yet found an ideal inexpensive catalyst. “We don’t know how the natural photosynthetic catalyst, which is based on four manganese atoms and a calcium atom, works,” Gust adds.

Gust and his colleagues have been looking into making molecular assemblies for artificial photosynthesis that more closely mimic their biological inspiration, and his team has managed to synthesize some of the elements that could go into such an assembly. Still, a lot more work is needed on this front. Organic molecules such as the ones nature uses tend to break down quickly. Whereas plants continually produce new proteins to replace broken ones, artificial leaves do not (yet) have the full chemicalsynthesis machinery of a living cell at their disposal.

Source of Information : Scientific American Magazine


About Me

In its broadest sense, science (from the Latin scientia, meaning "knowledge") refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research.

Fields of science are commonly classified along two major lines: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being experimented for its validity by other researchers working under the same conditions.


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