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Archive for February, 2014

air pollution

What is air pollution?

‘That may seem like a question that doesn’t really need to be asked. Surely, everyone already knows the answer. Air pollution is, well, wait now . . . OK, what is air pollution, exactly?

Ask most people “what is air pollution?” and they will answer “smog” (another word for ground-level ozone), the smelly stuff that turns the air brown or grey and hovers over urban centers like Los Angeles, Mexico City and Beijing. But air pollution comes in many forms, and may include a number of different pollutants and toxins in various combinations.

What Constitutes Air Pollution?
The two most widespread types of air pollution are the aforementioned ozone (smog) and particle pollution (soot), but air pollution also may include serious pollutants such as carbon monoxide, lead, nitrogen dioxide and sulfur dioxide, and toxins such as mercury, arsenic, benzene, formaldehyde and acid gases.

The specific composition of air pollution in a particular location depends primarily on the source, or sources, of the pollution. Automobile exhaust, coal-fired power plants, industrial factories and other pollution sources all spew different types of pollutants and toxins into the air.

Smog is grimy and dirty. Smelly and foul. It is smog, and it is more dangerous than it seems. Smog is a combination word derived from ‘smoke’ and ‘fog’. However, smog is much more that that.

One of the primary components of smog is ground-level ozone. While ozone in the stratosphere protects life on Earth from excess harmful UV radiation, ozone on the ground is hazardous. Photochemical smog (or just smog for short) is a term used to describe air pollution that is a result of the interaction of sunlight with certain chemicals in the atmosphere. Ground-level ozone is formed when vehicle emissions containing nitrogen oxides (primarily from vehicle exhaust) and volatile organic compounds (from paints, solvents, and fuel evaporation) interact in the presence of sunlight.
The excess amount of ozone that forms can lead to Alert Days issued for public heath. In addition, numerous medical conditions, such as asthma, are exacerbated by smog.

What is Smog?

What we typically call smog today is a mixture of air pollutants—nitrogen oxides and volatile organic compounds—that combine with sunlight to form ozone.

Ozone can be beneficial or harmful, good or bad, depending on its location. Ozone in the stratosphere, high above the Earth, acts as a barrier that protects human health and the environment from excessive amounts of solar radiation. On the other hand, ground-level ozone, trapped near the ground by heat inversions or other weather conditions, is what causes the respiratory distress and burning eyes associated with smog.

What Causes Smog?
Smog is produced by a set of complex photochemical reactions involving volatile organic compounds (VOCs), nitrogen oxides and sunlight, which form ground-level ozone.

Smog-forming pollutants come from many sources such as automobile exhaust, power plants, factories and many consumer products, including paint, hairspray, charcoal starter fluid, chemical solvents, and even plastic popcorn packaging. In typical urban areas, at least half of the smog precursors come from cars, buses, trucks, and boats.

Major smog occurrences often are linked to heavy motor vehicle traffic, high temperatures, sunshine, and calm winds. Weather and geography affect the location and severity of smog. Because temperature regulates the length of time it takes for smog to form, smog can occur more quickly and be more severe on a hot, sunny day.

When temperature inversions occur (that is, when warm air stays near the ground instead of rising) and the wind is calm, smog may remain trapped over a city for days. As traffic and other sources add more pollutants to the air, the smog gets worse. Ironically, smog is often more severe farther away from the sources of pollution, because the chemical reactions that cause smog take place in the atmosphere while pollutants are drifting on the wind.

What are the Effects of Smog?

Smog is made up of a combination of air pollutants that can compromise human health, harm the environment, and even cause property damage.

Smog can cause or aggravate health problems such as asthma, emphysema, chronic bronchitis and other respiratory problems as well as eye irritation and reduced resistance to colds and lung infections.

The ozone in smog also inhibits plant growth and can cause widespread damage to crops and forests.

Who is Most at Risk from Smog?

Anyone who engages in strenuous outdoor activity—from jogging to manual labor—may suffer smog-related health effects. Physical activity causes people to breathe faster and more deeply, exposing their lungs to more ozone and other pollutants. Four groups of people are particularly sensitive to ozone and other air pollutants in smog:

Children—Active children run the highest risks from exposure to smog. Children spend a lot of time playing outside, especially during summer vacation from school when smog is most likely to be a problem. As a group, children are also more prone to asthma—the most common chronic disease for children—and other respiratory ailments than adults.

Adults who are active outdoors—Healthy adults of any age who exercise or work outdoors are considered at higher risk from smog than people who spend more time indoors, because they have a higher level of exposure.

People with respiratory diseases—There is no medical evidence that the ozone in smog causes asthma or other chronic respiratory diseases, but people who live with such diseases are more sensitive and vulnerable to the effects of ozone. Typically, they will experience adverse effects sooner and at lower levels of exposure than those who are less sensitive.

People with unusual susceptibility to ozone—Some otherwise healthy people are simply more sensitive to ozone and other pollutants in smog than other people, and may experience more adverse health effects from exposure to smog than the average person.

Elderly people are often warned to stay indoors on heavy smog days. According to the most recent medical evidence, elderly people are not at increased risk of adverse health effects from smog because of their age. Like any other adults, however, elderly people will be at higher risk from exposure to smog if they suffer from respiratory diseases, are active outdoors, or are unusually susceptible to ozone.

How Can You Recognize or Detect Smog Where You Live?
Generally speaking, you will know smog when you see it. Smog is a visible form of air pollution that often appears as a thick haze. Look toward the horizon during daylight hours, and you can see how much smog is in the air.

In addition, most cities now measure the concentration of pollutants in the air and provide public reports—often published in newspapers and broadcast on local radio and television stations—when smog reaches potentially unsafe levels.

The U.S. Environmental Protection Agency (EPA) has developed the Air Quality Index (AQI) (formerly known as the Pollutant Standards Index) for reporting concentrations of ground-level ozone and other common air pollutants.

Air quality is measured by a nationwide monitoring system that records concentrations of ground-level ozone and several other air pollutants at more than a thousand locations across the United States. The EPA then interprets that data according to the standard AQI index, which ranges from zero to 500. The higher the AQI value for a specific pollutant, the greater the danger to public health and the environment.

Hazardous substances that include:

Particulate matter (PM) – These tiny particles of soot, ash, liquids cause a smoky haze in the air and contribute to heart disease and respiratory illnesses. Potentially more damaging than large particles are the fine particles of 2.5 micrometers or smaller that can be inhaled deep into the lungs. Particulate matter is considered one of six criteria pollutants under the National Ambient Air Quality Standards (NAAQS), as mandated by the Clean Air Act.

Sulfur oxides (SOx) – Sulfur dioxide (SO2) is among the oxides of sulfur linked with asthma and other respiratory illnesses. SOx are considered one of six criteria pollutants under the National Ambient Air Quality Standards (NAAQS), as mandated by the Clean Air Act.

Nitrogen oxides (NOx) – Nitrogen dioxide (NO2) is one of the oxides of nitrogen linked with elevated levels of asthma, emphysema, bronchitis, and heart disease. NOx are considered one of six criteria pollutants under the National Ambient Air Quality Standards (NAAQS), as mandated by the Clean Air Act.

Lead (Pb) – Lead contributes to neurological (brain) and renal (kidney) disorders. Lead is considered one of six criteria pollutants under the National Ambient Air Quality Standards (NAAQS), as mandated by the Clean Air Act.

Mercury (Hg) – Elemental mercury released in coal combustion can convert to a variety of hazardous mercury compounds and species. Mercury in various forms contributes to neurological (brain) disorders in developing children and adults. Because coal-fired boilers emit 48 tons of mercury annually in the U.S., the EPA has proposed pollutant standards for power plants.

Vapor-phase hydrocarbons (such as methane, alkanes, alkenes, benzenes, etc.)

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (known as dioxins and furans)

Hydrogen chloride gas (HCl)

Hydrogen fluoride gas (HF)

Source taken from: http://environment.about.com, http://energy.about.com

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itsumo nandodemo

いつも何度でも (Always with Me)
作詞/覚和歌子
作曲・歌/木村 弓

 

呼んでいる 胸のどこか奥で
いつも心踊る 夢を見たい

悲しみは 数えきれないけれど
その向こうできっと あなたに会える

繰り返すあやまちの そのたびひとは
ただ青い空の 青さを知る
果てしなく 道は続いて見えるけれど
この両手は 光を抱ける

さよならのときの 静かな胸
ゼロになるからだが 耳をすませる

生きている不思議 死んでいく不思議
花も風も街も みんなおなじ

ラララララララララ・・・・・・・・・
ホホホホルルルル・・・・・・・・

呼んでいる 胸のどこか奥で
いつも何度でも 夢を描こう

悲しみの数を 言い尽くすより
同じくちびるで そっとうたおう

閉じていく思い出の そのなかにいつも
忘れたくない ささやきを聞く
こなごなに砕かれた 鏡の上にも
新しい景色が 映される

はじまりの朝の 静かな窓
ゼロになるからだ 充たされてゆけ

海の彼方には もう探さない
輝くものは いつもここに
わたしのなかに 見つけられたから

 

Romaji
Yondeiru Mune no Dokoka Okude
Itsumo Kokoro Odoru Yume wo Mitai

Kanashimi wa Kazoekirenai kedo
Sono Mukou de Kitto Anata ni Aeru

Kurikaesu Ayamachi no Sonotabi Hito wa
Tada Aoi Sora no Aosa wo Shiru
Hateshinaku Michi wa Tsuzuite Mieru keredo
Kono Ryoute wa Hikari wo Dakeru

Sayonara no Toki no Shizukana Mune
Zero ni Naru Karada ga Mimi wo Sumaseru

Ikiteiru Fushigi Sinde Iku Fusigi
Hana mo Kaze mo Machi mo Minna Onaji

Yondeiru Mune no Dokoka Oku de
Itsumo Nando demo Yume wo Egakou

Kanashimi no Kazu wo Iitsukusu yori
Onaji Kuchibiru de Sotto Utaou

Tojiteiku Omoide no Sono Naka ni Itsumo
Wasure takunai Sasayaki wo Kiku
Konagona ni Kudakareta Kagami no Ue nimo
Atarashii Keshiki ga Utsusareru

Hajimari no Asa Shizuka na Mado
Zero ni Naru Karada Mitasarete Yuke

Umi no Kanata niwa Mou Sagasanai
Kagayaku Mono wa Itsumo Koko ni
Watashi no Naka ni Mitsukerareta Kara

 

English

Somewhere, a voice calls, in the depths of my heart
May I always be dreaming, the dreams that move my heart

So many tears of despair, uncountable through and through
I know on the other side of them I’ll be sure to find you

Everytime we fall down to the ground we look up to the sky above
We wake to it’s blueness, as if for the first time
Though the road is long, lonely and the end far away, out of sight
I can, with these arms, embrace the light

As I bid farewell my heart stops, tenderly I feel
My silent empty soul begins to listen to what is real

The wonder of living, the wonder of dying
The wind, town, and flowers, we all dance in unity

Somewhere, a voice calls, in the depths of my heart
keep dreaming your dreams, don’t ever let them part

Why speak of all your sadness or of life’s painfull woes
Instead let the same voice sing a gentle song for you

The whispering voice, we will never want to forget,
in each passing memory always there to guide you
When a miror has been broken, shattered pieces scattered on the ground
Glimpses of new life, are reflected all around

Window of beginning let shine the light of a new dawn
Let my silent, empty soul be filled and reborn

No need to search the land, nor sail across the sea
‘Cause it’s here shining inside me, it’s right here deep inside me
Thanks to you I’ve found the light, and it’s always with me.

 

(Song : Sen to Chihiro no Kamikakushi
(Spirited Away)
; Yumi Kimura)

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Photovoltaic-Pane_tcm18-219467

Shedding a little light on photovoltaic cells

Do you remember seeing your dad’s calculator that had that strange strip which powered it? Remember how you were playing with it when you asked him to help you solve your maths problem? Wasn’t it fun to keep your finger over the strip and after a time to see the calculator shut down? That was a photovoltaic cell, the thing that makes solar energy possible.

What does photovoltaic cell mean?

Look at the word photovoltaic and you may be able to guess its meaning. Give it a try. Photo means light, while voltaic means electricity. So how do you think they work? These cells work on the photovoltaic principle, converting light energy into electricity.

Why is this important?

The sun delivers more energy to the earth in one hour than we currently use from fossil fuels, nuclear power and all renewable energy sources combined in a year. Its potential as a renewable energy source, therefore, is vast.

Why we use photovoltaic cells

Photovoltaic cells allow us to use the solar energy of the sun to provide electric power. The sun is like a never-ending battery. It provides an important source of clean and renewable energy that is an alternate to polluting fossil fuels like coal. It is the world’s fastest growing technology with the amount of photovoltaic energy doubling every year.

In 1839 a French Scientist, Edmund Bequerel discovered that some materials produced small amounts of electricity whenever exposed to sunlight.

Think if you were to go camping somewhere. You will find that there are no power sockets to recharge anything! In such remote places a photovoltaic cells come in handy. You can use them in solar panels and also as solar modules. A solar module is when these cells are grouped together and connected in a package in one frame.

The difference between a photovoltaic and solar cells

You might be wondering what the difference between a solar cell and a photovoltaic cell is. Well a solar cell is designed to work in sunlight while a photovoltaic cell can use any form of light to generate electricity.

The first photovoltaic cell

Did you know that the first photovoltaic cell was made to provide power to space satellites. The Russians used them for their Sputnik 3 satellite back in 1957. But even before that, way back in 1839 a French Scientist, Edmund Bequerel discovered that some materials produced small amounts of electricity whenever exposed to sunlight. It was Einstein’s discoveries in 1905 that was the basis of all photo electric technology.

How photovoltaic cells work

Now that we know what a photovoltaic cell is, let us try to understand how these marvellous little things work. These cells are made of a special material called a semiconductor. Silicon is one of the most popular materials used as a semiconductor in these cells. A thin wafer of silicon is specially treated so that it forms an electric field. This field is positive on one side and negative on the other.

The photovoltaic material absorbs light rays. These light rays knock loose electrons from the atoms in the silicon releasing electrons in the process. These electrons are captured to release electricity. Two conductors are attached to the positive and negative sides. This completes the circuit and you can tap the electricity created. This is just like how you get electricity when you attach wires to the positive and negative terminal of a battery.

A solar cell is, in principle, a simple semiconductor device that converts light into electric energy. The conversion is accomplished by absorbing light and ionizing crystal atoms, thereby creating free, negatively charged electrons and positively charged ions. If these ions are created from the basic crystal atoms, then their ionized state can be exchanged readily to a neighbor from which it can be exchanged to another neighbor and so forth; that is, this ionized state is mobile; it behaves like an electron, and it is called a hole. It has properties similar to a free electron except that it has the opposite charge.

Solar cells can be made from single crystals, crystalline and amorphous semiconductors. For simplicity this article begins with a description of crystalline material.

Each photon of the light that has a high enough energy to be absorbed by the crystal’s atoms will set free an electron hole pair. The electron and hole are free to move through the lattice in a Brownian motion ; however, on average they will never move too far from each other. When the electron comes too close to a hole during their Brownian motion, they will recombine. On the other hand, when they experience an electric field, this will tend to separate the electrons from the holes; the electrons will drift toward the positive pole (the anode), and the positively charged holes will drift toward the cathode. Recombination will then take place in the external circuit (within the electric wires). Consequently a current will flow. Since it is generated by photons, one speaks of a photo current. And the semiconductor that performs this effect is called a photo conductor.

Photo conductors are passive devices. They react to light by changing their electric conductivity. In order to activate them an external electric power source, such as a battery, needs to be supplied to draw a current that increases with increasing light intensity. There are many photo conductor devices in our surroundings; as for example, in cameras, in streetlight controls to switch the lights off at dawn and on at dusk, or for light barriers in garage door safety controls.

However, if an electric field is incorporated into the semiconductor, it will separate the electrons and holes. The part of the crystal that accumulates the electrons will be negatively charged; the part that accumulates the holes will be positively charged. The resulting potential difference, referred to as an open circuit, can be picked up by an electrometer. When electrodes are provided at both sides, a current can flow between them. The crystal, when exposed to sunlight, acts as a battery and becomes a solar cell.

Fermi Energy

In order to make maximum use of the impinging photons and obtain maximum solar cell output, one has to maximize surface penetration, minimize reflection, and reduce obstacles, such as electrodes.

Solar cell efficiency is a most valuable measure of its performance. With sunlight impinging from the zenith on a sunny day, a surface perpendicular to the light receives about 1 kW/m 2 . When converted by a solar cell of 10 percent efficiency (presently reached or exceeded by most commercially available solar panels), this means that 100 W/m 2 in electrical energy can be harvested. This is sufficient if surface areas are ample and the panels are relatively inexpensive. However, where surface areas are at a premium—e.g., on top of a solar car or in some satellites—it is essential to use more efficient solar cells. These are available from carefully engineered Si cells or from GaAs, reaching efficiencies close to 25 percent.

Organic Chemists Contributing to the Development of Photovoltaics

As a result, the conversion of inexhaustible solar energy into electrical energy using PhotoVoltaic (PV) devices is one of the most attractive solutions to clean, renewable energy and will transform our future energy options. Photovoltaic power generation is currently dominated by photovoltaic cells that are based on inorganic materials such as polycrystalline silicon, cadmium telluride and copper indium selenide. To make power from photovoltaics truly competitive with fossil-fuel technologies the cost needs to be reduced. New Photovoltaic technologies, such as organic and dye-sensitised solar cells, are emerging from active research and development.

What did the organic chemists do?

Organic Photovoltaics (OPVs) are a promising cost-effective alternative to inorganic-based PV; and possess low cost, light-weight, and flexibility advantages. Organic molecules such as the polymer have high optical absorption coefficients compared to their inorganic counterparts, and incorporation of polymers of this type into photovoltaic cells offers an attractive alternative to current technology.

Palladium

Creation of complex organic polymers relies on innovative synthetic organic chemistry. In the case illustrated above, the polymer was synthesised from its monomer using a palladium-catalysed coupling procedure. This method of carbon-carbon bond-formation was recognised for its contribution to the construction of complex organic molecules by the 2010 Nobel Prize for chemistry awarded to Professors Heck, Negishi and Suzuki.

Cells based on OPVs are currently relatively inefficient due to energy leakage problems and it is estimated that improvements in cell performance, operational stability and fabrication methods are needed to take power conversion efficiencies from the current levels of around 6-8% to a competitive 15%. Organic chemistry provides an opportunity to address this challenge at the molecular level, but it is recognised that the vast parameter space available will necessitate the definition and use of inspired molecular design guidelines. Success will provide significantly lower cost/higher volume manufacturing procedures of flexible devices that in turn will provide opportunities for the production of a wide range of new applications.

What is the impact?

There is already significant research related to enhancing the efficiency of solar conversion. Solar energy through photovoltaics will be a part of the energy mix of the future. This will require an interdisciplinary approach to generate novel photovoltaic materials and new advanced device concepts that will lead to commercialisation of high-efficiency and low-cost solar cells.

 

“Green chemistry is not just a mere catch phrase: it is the key to the survival of mankind”
Professor Ryoji Noyori – Nobel Laureate

 

Read more:
http://www.chemistryexplained.com/Ru-Sp/Solar-Cells.html; http://humantouchofchemistry.com/shedding-a-little-light-on-photovoltaic-cells.htm;
http://www.rsc.org/Membership/Networking/InterestGroups/OrganicDivision/organic-chemistry-case-studies/organic-chemistry-photovoltaics.asp

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I Will Never Forget You

Sooner or later they say
That it all gets easier
Take it one tear at a time

And I wake up one day
To find some closure
Shinin’ like a sunlight through the blinds

No matter how much time may pass between us
You’ll never be more than a memory away

Cause I will never forget you
No, I will never forget you

The whisper of the evening rain
On the bedroom window
Like the sky is missin’ you

The flicker of a candle flame
There’s only one shadow
Oh, but I can still see two

No matter how much pain I have to go through
It’s better than feelin’ nothin’ for you at all

Cause I will never forget you
No, I will never forget you

When I’m sleepin’
When I’m dreamin’
When I’m awake
I got the feelin’ that
I’ll never get you out of my mind

Oh, and I will never forget you
No, I will never forget you

Never forget you

Oh Oh

Never forget you

(artist: Danielle Bradbery lyrics,  source taken from : http://www.lyricsmania.com)

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