|SCIENCE & TECHNOLOGY|
Acid rain and its effect
Games that help raise self-esteem
Nano-scale trees created
UNDERSTANDING THE UNIVERSE
Acid rain and its effect
When rain or snow falling from the atmosphere contains acids like H2SO4 and HNO3 then we say there is acid rain. In other words it is the polluted rain water. In order to understand the term acid rain we have to divide it into two categories: wet deposition and dry deposition.
The term deposition has been used due to acid fallout of the atmosphere. Wet deposition refers to acidic rain, fog, and snow. Dry deposition refers to acidic gases and particles. The earth’s gravity works to continually pull dry particles back to earth. Uneven heating of the earth results in global winds in the atmosphere. Global winds provide the energy for long-range travel of the gases, liquids, and dust in the atmosphere, before falling back to the ground.
Fossil fuels contain compounds of sulphur and nitrogen in addition to carbon.
These waste gases are released by the combustion of fossil fuels by automobiles, electric power plants, and smelting and refining facilities.
The combustion of fuels contributes significantly to atmospheric pollution. It has led to the acidification of rain and freshwater aquatic systems. Acid rain is a worldwide problem
The burning of fossil fuels gives CO2.The gaseous CO2 dissolves in water droplets to form weak acid, carbonic acid.
CO2 being insoluble in water,is not the major component of acid rain as the SO2 and NO2 .The burning of fossil fuels like coal and oil products by automobiles and power plants releases large amounts of sulphur dioxide and nitrogen oxides into the air. While being transported by winds, some of these particles get caught up in clouds. When sulphur dioxide and nitrogen oxides gases and particles come in contact with water droplets in clouds. The SO2 and NO2 undergo many photochemical reactions in atmosphere to form H2SO4 and HNO3, resulting in acid rain.
The components subsequently fall down to the earth in the form of rain or snow. This polluted rain is called acid rain. In rain the ph of water decreases. Acid rain is defined as precipitation with a pH of less than 5.7.
Acid rain is very damaging Acid rain is found to speed up the natural decay of stone monuments and historical buildings made up of marble, limestone, slate etc. these materials on reacting with rain water get damaged.
As a result of acid rain invaluable statues and buildings are deteriorating in Greece and Italy. Many invaluable statues have partially damaged. Taj Mahal of India is facing same problem.
The adverse effects on life in fresh water acid rain primarily affects sensitive bodies of water, which are located in watersheds whose soils have a limited ability to neutralise acidic compounds (called "buffering capacity"). Lakes and streams become acidic (pH value goes down) when the water itself and its surrounding soil cannot buffer the acid rain enough to neutralise it.
In areas where buffering capacity is low, acid rain also releases aluminum from soils into lakes and streams; aluminum is highly toxic to many species of aquatic organisms.
It damages leaves of trees and plants and retards the growth of forests .It damages various kinds of vegetation, including agricultural crops and trees, chiefly by inhibiting nitrogen fixation and leaching nutrients from foliage.
The rain water also corrodes metals, the acidified water dissolves metal oxides in the soil and releases Al (aluminium), Zn (zinc), Mn (manganese), Fe (iron). All these metals are toxic if present in large quantity in any type of water.
Sulphates and nitrates that form in the atmosphere from sulphur dioxide (SO2) and nitrogen oxides (NOX) emissions contribute to visibility impairment, meaning we can’t see as far or as clearly through the air.
Games that help raise self-esteem
Can computer games help raise self-esteem? Absolutely. In a world-first study, researchers from McGill University’s Department of Psychology have created and tested computer games that are specifically designed to help people enhance their self-acceptance.
Available for public consultation at http://www.selfesteemgames.mcgill.ca/, the games have catchy names such as Wham!, EyeSpy: The Matrix and Grow Your Chi.
All three games were developed by doctoral students from McGill’s Department of Psychology: Jodene Baccus, St`E9phane Dandeneau and Maya Sakellaropoulo, under the direction and supervision of Mark Baldwin, an associate psychology professor.
"For people with low self-esteem, negative thought patterns occur automatically and often involuntarily," explains Baldwin, "leading them to selectively focus their attention on failures and rejections." The solution? People with ‘automatic’ negative personal outlooks need to condition their minds towards positive views and learn to be more accepting of themselves.
Nano-scale trees created
For the last few years scientists at the Nanometer Consortium at Lund University have been able to make nanowires, tiny wires just a few millionths of a millimeter "thick" and made of semiconducting material of great potential in the electronics industry. Now they have managed to produce "nanotrees," in fact tiny forests on the same scale.
This is described in an article ("Synthesis of branched ‘nanotrees’ by controlled seeding of multiple branching events") in the journal Nature Materials, whose Web edition was published on May 2. The paper edition should be published in June.
"This opens the possibility of producing ever more complex structures on the nano scale, structures that may offer tremendous potential for applications like solar cells, low-energy lighting, sensors, etc, explains Professor Lars Samuelson, solid state physicist at Lund Institute of Technology.
"It is also an example of interdisciplinary collaboration between physics and chemistry, that is, between my research team at Fysicum and the one at Kemicentrum headed by Professor Reine Wallenberg," added Samuelson.
He was the one who came up with the idea of nanotrees. The person who actually produced them is one of his doctoral students, Kimberly A. Dick, who came to Lund from Waterloo University, Canada.
The scientists produce nanowires by first
creating tiny nanoparticles of gold and placing them on a semiconducting tray.
Then they release reactive molecules that contain the atoms that they want the
nanowires to consist of — for instance, to make nanowires of silicon (Si) or
of alloyed semiconductors such as indium arsenide (InAs) or gallium phosphide (GaP).
UNDERSTANDING THE UNIVERSE
Why can we see the Sun and the Moon together in the sky? We know that the Moon shines with light of the Sun.
It is true that the Moon shines with the light of the Sun. But surely we cannot prevent the light from the Sun falling on the Moon if it is within its sight, which is most of the time except when the earth shields the Moon during an eclipse.
The 24-hour rotation period of the earth and the 27-day revolution of the Moon around the earth determine the progressive change in the portion of the Moon that appears illuminated in a certain day.
On the new Moon day the Sun is almost behind the Moon — only a tiny sliver is visible.
As the week progresses the angle between the directions of the Sun and the Moon changes and therefore increasing fraction of the illuminated Moon is seen of the earth.
During this period it is not strange that we are able to see the Sun and the Moon both during some part of the day.
Finally, two weeks later, we can see the full Moon rising in the east while the Sun has just set in the west. Both on the new Moon day and the full Moon day the Sun, the earth and the Moon are approximately in the same line.
When they happen to be exactly in the same line we get an eclipse — lunar or solar.
Some people have a talent for singing, while others do not. Is it hereditary?
I suspect there might be some truth in what you say, but I am not sure.
Rhythm and beat are intrinsic elements of all humans, indeed of all living things.
We are all bundles of clocks.
For some lucky ones, these intrinsic clocks create magnificent combinations not accessible to others.
It does appear that the great creators and performers of music belong in special class whose doors of perception are wider and unobstructed.
All the same music is imbibed from the environment when young. Intrinsic capabilities are themselves not enough.
Much nurturing is required — and lot of riaaz. Those not exposed to good music in their childhood are deprived.
What is the difference
between a glass and a wood screen in respect of sound insulation? Though
a thin layer of insulation can stop light from coming in despite its
higher speed, sound noise easily penetrates.
Let me, right in the beginning, clarify that the difference between the speed of light and sound is irrelevant for this discussion. Light interacts with the material that comes in the way depending on its atomic or molecular structure. Sound is a pressure wave in air that physically impacts and vibrates parts of the material.
Given the same thickness wood is likely to be a better sound insulator, particularly when the wood is soft. This is because sound gets into the tiny groves and pores of the wood and be used up in subsonic vibrations of the material resulting in a little heating. Glass might vibrate as a whole. If we use two layers of glass with reduced pressure in between we might get excellent insulation. Size and thickness of the glass plate also matter. I have seen airport buildings with large plate glass windows that are so quiet inside that you can hear a pin drop 10 feet away. Sound studios used for recordings have layers of soft board on the walls and ceiling and the doors are thick sandwiches with glass wool enclosed between inner and outer layers of wood. In conference rooms where confidential matters are being discussed doors are often draped with quilts of cotton or some such material.
Quietness in a sound-insulated room is also determined by the way the walls and ceiling of the room have been treated. If they can reflect sound then the room would not be so quiet because the sound leaking in from the smallest chink in the outer walls would be reflected back and forth. If, on the other hand the interior surfaces are covered with sound absorbing material small leakages from outside would be absorbed and quietness would be maintained. Acoustic design of buildings is both a science and an art.
New products & discoveries
1,800 new species found
Genome experts who took on a patch of ocean for a mass gene-sequencing project said they had discovered at least 1,800 new species of microbes and changed some of their fundamental ideas about ocean biology.
Genome pioneer Craig Venter and other scientists analysed the tiny organisms in a sample of water from the Sargasso Sea off Bermuda and then sequenced the genetic code.
They used the technique that Venter, now at his own non-profit institute, used to accelerate the sequencing of the human gene map.
Called whole-genome shotgun sequencing, it uses powerful computers to re-assemble the genetic code. — Reuters
Brain changes in gay sheep
Researchers who found homosexual rams in a herd of sheep said they had found changes in the brains of the "gay" animals. The results, published in the latest issue of the Journal Endocrinology, tend to support studies in humans that have found anatomical differences between the brains of heterosexual men and homosexual men.
The researchers at the Oregon Health & Science University School of Medicine found certain groups of brain cells were different between rams and ewes in a part of the sheep brain controlling sexual behavior. — Reuters
Size does matter
A study of the brains of primates ranging from tiny bush babies to humans and apes shows that size really may matter.
All primates have an unusually large
frontal cortex, a part of the brain used by humans for higher thought
and reasoning, they found. From lemurs to chimpanzees, that part of
the brain is especially large compared with overall brain size, the
California Institute of Technology team found. — Reuters