Central Department Of Chemistry

Central Department Of Chemistry
Me at Central Department oF chemistry

Sunday, October 19, 2014

Microwave Ovens & Public Health

Microwave ovens are tremendously used in the kitchen. Though, its use in urban area of Nepal is relatively low due to the uneven schedule of load shedding. Many people have misconceptions that the food cooked with microwaves are as hazardous as the radio active elements. But actually it is not so. Food cooked with microwave ovens are safer to eat,condition is that proper handling of the oven and food is must.

                                                                                Fig: Microwave oven

WHAT ARE MICROWAVES?

Microwaves are high frequency radio waves (radiofrequency fields) and, like visible radiation (light), are part of the electromagnetic spectrum. Microwaves are used primarily for TV broadcasting, radar for air and sea navigational aids, and telecommunications including mobile phones. They are also used in industry for processing materials, in medicine for diathermy treatment and in kitchens for cooking food.
Microwaves are reflected, transmitted or absorbed by materials in their path, in a similar manner to light. Metallic materials totally reflect microwaves while non-metallic materials such as glass and some plastics are mostly transparent to microwaves.

Materials containing water, for example foods, fluids or tissues, readily absorb microwave energy, which is then converted into heat. This Information Sheet discusses the operation and safety aspects of microwave ovens used in the home. More details about the nature of electromagnetic fields and health effects of radiofrequency and microwave fields are available in WHO Fact Sheets 182 and 183.

ARE MICROWAVE OVENS SAFE?

When used according to manufacturers' instructions, microwave ovens are safe and convenient for heating and cooking a variety of foods. However, several precautions need to be taken, specifically with regards to potential exposure to microwaves, thermal burns and food handling.
Microwave safety: The design of microwave ovens ensures that the microwaves are contained within the oven and can only be present when the oven is switched on and the door is shut. Leakage around and through the glass door is limited by design to a level well below that recommended by international standards. However, microwave leakage could still occur around damaged, dirty or modified microwave ovens. It is therefore important that the oven is maintained in good condition. Users should check that the door closes properly and that the safety interlock devices, fitted to the door to prevent microwaves from being generated while it is open, work correctly. The door seals should be kept clean and there should be no visible signs of damage to the seals or the outer casing of the oven. If any faults are found or parts of the oven are damaged, it should not be used until it has been repaired by an appropriately qualified service engineer.

Microwave energy can be absorbed by the body and produce heat in exposed tissues. Organs with a poor blood supply and temperature control, such as the eye, or temperature-sensitive tissue like the testes, have a higher risk of heat damage. However, thermal damage would only occur from long exposures to very high power levels, well in excess of those measured around microwave ovens.

Thermal safety: Burn injuries can result from handling hot items heated in a microwave oven, in the same way as items heated using conventional ovens or cooking surfaces. However, heating food in a microwave oven presents some peculiarities. Boiling water on a conventional stove allows steam to escape through bubbling action as the water begins to boil. In a microwave oven there may be no bubbles on the walls of the container and the water will super-heat and may suddenly boil. This sudden boiling may be triggered by a single bubble in the liquid or by the introduction of a foreign element such as a spoon. People have been severely burned by super-heated water.

Another peculiarity of microwave cooking relates to the thermal response of specific foods. Certain items with non-porous surfaces (e.g. hotdogs) or composed of materials that heat at different rates (e.g. yolk and white of eggs) heat unevenly and may explode. This can happen if eggs or chestnuts are cooked in their shells.

Food safety: Food safety is an important health issue. In a microwave oven, the rate of heating depends on the power rating of the oven and on the water content, density and amount of food being heated. Microwave energy does not penetrate well in thicker pieces of food, and may produce uneven cooking. This can lead to a health risk if parts of the food are not heated sufficiently to kill potentially dangerous micro-organisms. Because of the potential for uneven distribution of cooking, food heated in a microwave oven should rest for several minutes after cooking is completed to allow the heat to distribute throughout the food.

Food cooked in a microwave oven is as safe, and has the same nutrient value, as food cooked in a conventional oven. The main difference between these two methods of cooking is that microwave energy penetrates deeper into the food and reduces the time for heat to be conducted throughout the food, thus reducing the overall cooking time.

Only certain microwave ovens are designed to sterilize items (for example baby’s milk bottles). The user should follow the manufacturer's instructions for this type of application.

Misconceptions: To dispel some misconceptions, it is important to realize that food cooked in a microwave oven does not become "radioactive". Nor does any microwave energy remain in the cavity or the food after the microwave oven is switched off. In this respect, microwaves act just like light; when the light bulb is turned off, no light remains.

HOW DO MICROWAVE OVENS WORK?

Domestic microwave ovens operate at a frequency of 2450 MHz with a power usually ranging from 500 to 1100 watts. Microwaves are produced by an electronic tube called a magnetron. Once the oven is switched on, the microwaves are dispersed in the oven cavity and reflected by a stirrer fan so the microwaves are propagated in all directions. They are reflected by the metal sides of the oven cavity and absorbed by the food. Uniformity of heating in the food is usually assisted by having the food on a rotating turntable in the oven. Water molecules vibrate when they absorb microwave energy, and the friction between the molecules results in heating which cooks the food.

Unlike conventional ovens, microwaves are absorbed only in the food and not in the surrounding oven cavity. Only dishes and containers specifically designed for microwave cooking should be used. Certain materials, such as plastics not suitable for microwave oven, may melt or burst into flames if overheated. Microwaves do not directly heat food containers which are designed for microwave cooking. These materials usually get warm only from being in contact with the hot food.

Oven manufacturers do not recommend operating an empty oven. In the absence of food, the microwave energy can reflect back into the magnetron and may damage it.

Microwave oven users should carefully read and comply with the manufacturer’s instructions because new ovens vary widely in design and performance. While most modern ovens can tolerate some food packaging made of metal, oven manufacturers generally recommend not placing metal in the oven, particularly not close to the walls, as this could cause electrical arcing and damage the oven walls. Also, because metal reflects microwaves, food wrapped in metal foil will not be cooked, while food not in metal wrap may receive more energy than intended, causing uneven cooking.

INTERNATIONAL STANDARDS

Several countries, as well as the International Electrotechnical Commission (IEC), the International Committee on Electromagnetic Safety (ICES) of the Institute of Electrical and Electronics Engineers (IEEE) and the European Committee for Electrotechnical Standardization (CENELEC), have set a product emission limit of 50 watts per square metre (W/m2) at any point 5 cm away from the external surfaces of the oven. In practice, emissions from modern domestic microwave ovens are substantially below this international limit, and have interlocks that prevent people being exposed to microwaves while the oven is on. Moreover, exposure decreases rapidly with distance; e.g. a person 50 cm from the oven receives about one one-hundredth of the microwave exposure of a person 5 cm away.

These product emission limits are defined for the purpose of compliance testing, not specifically exposure protection. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has published guidelines on exposure limits for the whole EMF part of the spectrum. Exposure guidelines in the microwave range are set at a level that prevents any known adverse health effect. Exposure limits for workers and for the general public are set well below levels where any hazardous heating occurs from microwave exposure. The emission limit for microwave ovens mentioned above is consistent with the exposure limits recommended by ICNIRP.

Source: WHO

Tuesday, May 27, 2014

Nepal Chemical Society (NCS) aims to organize Conference on Advanced Materals and Nanotechnology

Nepal Chemical Society (NCS), an association of all Chemistry Professionals of Nepal is going to organize an "International Conference on Materials and Nano-Technology" on 4-6 November 2014 in Kathmandu, Nepal. NCS organizes different programs in certain intervals of time.  The society is dedicated to contribute for the overall progress and prosperity of nation by promoting the research activities and capabilities as well as the quality chemical education of the country. According to NSC executive member Ram Chandra Kandel, the conference is the continuation of International Conference on Advanced Materials and Nano- Technology (ICAMN) for Sustainable Development, 2011.


Current president of NCS is Dr. Deba Bahadur Khadka. He had been elected as president along with 11 executive members by more than thousands of members recently.

Any query about the conference can be directed to the President of NCS. He can be contacted directly at: khadkadeba@yahoo.com.

Sunday, May 11, 2014

How Sugar is produced from Sugarcane?



Most of we in our childhood might have wondered about the production of sugar from sugarcane. Moreover than production we wonder how fine crystals might have formed. Sugar (chemically sucrose) is produced mainly from sugarcane. Beside sugarcane, sugar beats and other chemical synthesis can be utilized for the manufacture.

Fig: Sugarcane
Sugarcane is traditionally refined into sugar in two stages. In the first stage, raw sugar is produced by the milling of freshly harvested sugarcane. In a sugar mill, sugarcane is washed, chopped, and shredded (tear into narrow pieces) by revolving knives. The shredded cane is mixed with water and crushed. The juices (containing 10-15 percent sucrose) are collected and mixed with lime to adjust pH to 7, prevent decay into glucose and fructose, and precipitate impurities. The lime and other suspended solids are settled out, and the clarified juice is concentrated in a multiple-effect evaporator to make a syrup with about 60 weight percent sucrose. 


What is multiple-effect evaporator?

A multiple-effect evaporator, invented by American Engineer Norbert Rillieux, is an apparatus for efficiently using the heat from steam to evaporate water. In a multiple-effect evaporator, water is boiled in a sequence of vessels, each held at a lower pressure than the last. Because the boiling temperature of water decreases as pressure decreases, the vapor boiled off in one vessel can be used to heat the next, and only the first vessel (at the highest pressure) requires an external source of heat.

The syrup is further concentrated under vacuum until it becomes supersaturated, and then seeded with crystalline sugar. Upon cooling, sugar crystallizes out of the syrup. Centrifuging then separates the sugar from the remaining liquid (molasses). Raw sugar has a yellow to brown color. Sometimes sugar is consumed locally at this stage, but usually undergoes further purification. Sulfur dioxide is bubbled through the cane juice subsequent to crystallization in a process, known as "sulfitation". This process inhibits color forming reactions and stabilizes the sugar juices to produce “mill white” or “plantation white” sugar.

The fibrous solids, called bagasse, remaining after the crushing of the shredded sugarcane, are burned for fuel, which helps a sugar mill to become self-sufficient in energy. Any excess bagasse can be used for animal feed, to produce paper, or burned to generate electricity for the local power grid.




Fig: Flow chart of refining of Sugar from Sugarcane (source: www.wikipedia.org)         














Wednesday, April 30, 2014

Powdered Alcohol made available soon in Nepal

As we know, human beings have been enjoying alcohol for thousands of years in a variety of forms, but one aspect has always remained constant: it was liquid. Inventor Mark Phillips has created a product that could revolutionize what we think about cocktails and gives a whole new meaning to ‘dry martini’: powdered alcohol. The product is commonly known as Palcohol. 

To turn Palcohol into your favorite adult beverage, you just add the powdered alcohol (which comes in a package sort of like a sugar packet) to five ounces of water. It currently comes in six varieties: rum, vodka, cosmopolitan, mojito, margarita, and lemon drop. Swapping out the water for a different mixer (such as soda or juice) can personalize the drink to suit an individual’s taste preference. 

Many are excited because Palcohol could be discretely brought in to places where liquor is not available or exorbitantly priced, such as sporting events, concerts, movie theaters, airplanes, cruise ships, and the like. However, it is for this precise reason that many are opposing its availability. 

The Palcohol is already available in the USA and it is estimated that the same product can be made available in Nepal within a year. According to the source the importer should take an approval from Ministry of Health, Nepal. The cost of the product will be cheaper as compared to the liquor because of the reduction cost in packing and delivery. 


Source: www.ifscience.com

Humans have been enjoying alcohol for thousands of years in a variety of forms, but one aspect has always remained constant: it was liquid. Inventor Mark Phillips has created a product that could revolutionize what we think about cocktails and gives a whole new meaning to ‘dry martini’: powdered alcohol. The product, called Palcohol, has just gained approval from the U.S. Alcohol and Tobacco Tax and Trade Bureau (TTB). (See update at the bottom)
To turn Palcohol into your favorite adult beverage, you just add the powdered alcohol (which comes in a package sort of like a sugar packet) to five ounces of water. It currently comes in six varieties: rum, vodka, cosmopolitan, mojito, margarita, and lemon drop. Swapping out the water for a different mixer (such as soda or juice) can personalize the drink to suit an individual’s taste preference.
Many are excited because Palcohol could be discretely brought in to places where liquor is not available or exorbitantly priced, such as sporting events, concerts, movie theaters, airplanes, cruise ships, and the like. However, it is for this precise reason that many are opposing its availability.
One of the first questions to be brought up regarding the product was if it could be snorted. The short answer is yes, but it’s a terrible idea. The Palcohol website says this about snorting: “We have seen comments about goofballs wanting to snort it. Don't do it! It is not a responsible or smart way to use the product. To take precautions against this action, we've added volume to the powder so it would take more than a half of a cup of powder to get the equivalent of one drink up your nose. You would feel a lot of pain for very little gain. Just use it the right way.”
Despite approval from the TTB, there are many obstacles Palcohol faces before it shows up on store shelves, as each state must also approve the sale of powdered alcohol. Even if it is perfectly legal, retailers and wholesalers will also need to support its sale. It is almost certain that those who oppose it will be putting considerable pressure on them to oppose it, so there’s no telling how everything will play out. Despite the legal uncertainty, the minds behind Palcohol are still planning for a fall availability. There are no current predictions on how much the product will cost.

Read more at http://www.iflscience.com/chemistry/powdered-alcohol-coming-us#TSsXcgowdFXxt2Q2.99
Humans have been enjoying alcohol for thousands of years in a variety of forms, but one aspect has always remained constant: it was liquid. Inventor Mark Phillips has created a product that could revolutionize what we think about cocktails and gives a whole new meaning to ‘dry martini’: powdered alcohol. The product, called Palcohol, has just gained approval from the U.S. Alcohol and Tobacco Tax and Trade Bureau (TTB). (See update at the bottom)
To turn Palcohol into your favorite adult beverage, you just add the powdered alcohol (which comes in a package sort of like a sugar packet) to five ounces of water. It currently comes in six varieties: rum, vodka, cosmopolitan, mojito, margarita, and lemon drop. Swapping out the water for a different mixer (such as soda or juice) can personalize the drink to suit an individual’s taste preference.
Many are excited because Palcohol could be discretely brought in to places where liquor is not available or exorbitantly priced, such as sporting events, concerts, movie theaters, airplanes, cruise ships, and the like. However, it is for this precise reason that many are opposing its availability.
One of the first questions to be brought up regarding the product was if it could be snorted. The short answer is yes, but it’s a terrible idea. The Palcohol website says this about snorting: “We have seen comments about goofballs wanting to snort it. Don't do it! It is not a responsible or smart way to use the product. To take precautions against this action, we've added volume to the powder so it would take more than a half of a cup of powder to get the equivalent of one drink up your nose. You would feel a lot of pain for very little gain. Just use it the right way.”
Despite approval from the TTB, there are many obstacles Palcohol faces before it shows up on store shelves, as each state must also approve the sale of powdered alcohol. Even if it is perfectly legal, retailers and wholesalers will also need to support its sale. It is almost certain that those who oppose it will be putting considerable pressure on them to oppose it, so there’s no telling how everything will play out. Despite the legal uncertainty, the minds behind Palcohol are still planning for a fall availability. There are no current predictions on how much the product will cost.

Read more at http://www.iflscience.com/chemistry/powdered-alcohol-coming-us#TSsXcgowdFXxt2Q2.99

Tuesday, March 25, 2014

Conference going to be held in Advanced Materials

22nd International Conference on Polymer Characterization organized by World Forum on Advanced Materials (PolyChar-22) is going to be held from April 7 in Stellenbosch, South Africa. According to Professor Peter Mallon of University of Stellenbosch, South Africa the program will end formally in 10th April.
 
It is worthy to remember here that Polychar-19 was held in Kathmandu, Nepal in mid April 2011. It was organized by Nepal Polymer Society.   
 
Assoc. Prof. Rameshwar Adhikari  is the Chairman of this Organization.


More about the Polychar-22, any one can contact directly to Prof. P Mallon in his personal email address.

- From IUPAC News 

Sunday, November 17, 2013

Explosive Chemicals and Detonators threatens the 2nd CA poll in Nepal

The CA poll which is scheduled for 19th November 2013 has been continuously marred by the Baidhya Maoist and their alley wings. Theses parties are not enrolled in the main election and are trying to fail the Election campaign led by other party candidates.

The threat of life has been increasing in recent days since several explosive chemicals and detonators, cooker bomb, petrol bomb are being deployed on the main entrance gate of several innocent people. The buses are at halt due the strike called by Maoist(Baidhya) led parties. Light vehicles are at the target of the strikers. There is no any day which is far beyond the main news of bombing on the running micro bus or motorcycles.

Due the Election  and strike the Central Department of Chemistry (CDC), Kirtipur has been closed. Other educational institutes are also closed. Different programs like seminars, discussion programs and thesis defense programs related to the Chemistry have been postponed in the Central Department of Chemistry, Kirtipur till 21st November 2013.

Sunday, March 11, 2012

Symposia on Advanced Materials is to be held in Kathmandu

Kathmandu Symposia on Advanced Materials - 2012
(May 9-12)
(KaSAM 2012)

A Symposia on Advanced Materials is to held in Kathmandu on May 9-12,2012. Kathmandu symposia on Advanced Materials (KaSAM) is an IUPAC sponsered program.
The KaSAM is aimed at strengthening
networking of materials scientists from South Asian Countries with those from
rest of the world; and has the motto: Cross-Linking Science and Virtues.
The objective of the KaSAM International Conference is to provide rigorous
discussion forum for the materials scientists on recent advances, challenges
and solution paths in different areas of Materials Science and Engineering
(MSE). Polymeric Materials will form integral part of KaSAM endeavours. The
conference is hoped to be a milestone also in promoting education and
researches in the field of advanced materials in Nepal.
The KaSAM-2012 will focus on Nanostructured
and Biorelated Materials providing a platform for presentation of
innovations in MSE from academia and industries. The conference will be
accompanied by a one day Short Course: Recent Trends in Materials Science
and a one day special Workshop: All about Bamboo.
The Short Course is targeted to the
students, young researchers and new comers in the field and will give an
overview of recent developments and research trends in synthesis,
characterization and applications of new materials. The idea behind the Bamboo
Workshop is to bring the experts involved in agriculture, environmental
issues, economy and technological aspects of this nature’s wonder material
together in a common platform in order to discuss the issues such as
advancements in the bamboo science including potential utilization in
fabrication of new materials, impacts on environment.




Organized by
Nepal Polymer
Institute (NPI), Kathmandu in association with
Tribhuvan
University, Kathmandu; Kathmandu University, Kavre and Université de Rouen,
Rouen
Venue: Park Village
Resort & Hotel, Budhanilkantha, Kathmandu


IUPAC Sponsored Conference

Saturday, November 5, 2011

IUPAC awarded the 2011 winners of the IUPAC Prof. Jiang Novel Materials Youth Prize

The International Union of Pure and Applied Chemistry (IUPAC) awarded two winners of the IUPAC Prof. Jiang Novel Materials Youth Prize for the year 2011 at the 7th International Conference on Novel Materials and their Synthesis, which was organized in Shanghai during 16-21 October, 2011.
The two winners are:
  • Prof. Dr. Zhibo Li, Institute of Chemistry, Chinese Academy of Sciences, China
  • Dr. Jr-Hau He, National Taiwan University, Taiwan, China

The winners each received a cash prize of USD 1000 and a refunding of return air-tickets to the IUPAC 7th International Conference on Novel Materials and their Synthesis. Each prizewinner was invited to present a Keynote Lecture at the IUPAC Conference describing their award winning work and to submit a short critical review on aspects of their research topics to be published in Pure and Applied Chemistry. The next awarding for this Youth Prize will be given in 2013 to two winners, and the application information will be described on the IUPAC web site www.iupac.org and the Conference web site www.nms-iupac.org.

Awards:
  • Best Oral Presentation by Postdoc, Graduate Research Seminar in Gordon Research Conference (Polymers West) - 2007
  • Gordon Research Conference Travel Award, 2007
  • Chinese Academy of Sciences Fellowship, 1999
He published more 30 peer-reviewed journal papers including Science, Nature, JACS, Nano Letters, Macromolecules, and Langmuir with more than 900 citations. His present citation is “Developing novel ABC star copolymer system toward multicompartment micelles”.



-News from IUPAC

Saturday, July 2, 2011

Conference Organized by NCS is over!!!

       The Nepal Chemical Society (NCS) in coperation with CENTRAL DEPARTMENT of CHEMISTRY,KIRTIPUR , KATHMANDU had organized a International Conference on "ADVANCED MATERIALS & NANOTECHNOLOGY". In that very conference  Scientist all over the world had joined. Conference was held in Kathmandu on this Oct.21 to 23, 2011.

     According to a member  of Chemical Society of Nepal it  tried to investigate and materalize the recent investigation going through nation and not only this it had provided unique opportunity for participants to share thier knowledge and interact with the global scientists in the field of advanced materials and nanotechnology and expand their scintific Horizons!! Its motto was International Conference on Advanced Materials and Nanotechnology (ICAMN)  for Sustainable Development.

      It is reminded that on March, 2011 a similar type of Conference was organized by Nepal Polymer Institute in Kathmandu.

Friday, July 1, 2011

Educational Tour Of CDC student



July7,Kathmandu.The student of the Central Department of Chemistry,Kirtipur" The 2009 Batch" have successfully organized the two day Educational Excursion.The excursion had been scheduled to Devghat,Sauraha,Hetauda,Daman and back to Kathmandu via byroad.

Since the Excursion was scheduled in the Rainy season,there was fear that rain may affect the free movement and the observation programme but luckly weather supported.

Students observed the Yeti paint Company curiously.The company provided a technician to make student easy to understand the related inquires.

Finally students returned to Kathmandu via ByRoad.On the Byroad they had taken the taste of Dhido and Local Kukhura ko Masu.