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My friend heard that tea is worse for drinking than water because "cells have a special membrane and tea has special supplements and membrane doesn't let tea pass and this is why skin is dry even when you hydrate with tea a lot", something about "lipid bilayer".
Is there is some nice scientific article on water andd tea difference to human organism?
Your question is very awkward.
Let's define Tea as boiling leaves in water. At the end, you remove the leaves and drink the flavoured water.
At this point, the "tea" is still very much water - as in tea is water with dissolved chemicals from the leaves. Note, the word chemicals is not to be interpreted in a negative way because everything (including water) is a chemical.
So, the difference between tea and water are the chemicals that dissolve. What are these chemicals? The answer to that depends very much on the tea. Another difference is the temperature - tea is typically hot.
You can look at this article about chemicals in green tea and their associated health benefits. You can do further searches for other tea types and for each of those chemicals.
In short, no you do not get dehydrated because of tea vs. water. Dry skin can be caused by a lot of different reasons. Oh and no, caffeine doesn't cause any significant amount of dehydration as far as I know.
Depends on the tea, but most tea (unless herbal) contains caffeine, which is a diuretic. This means it dehydrates, and why one might experience drier skin. However, this is not a direct relationship and the actual reason why one's skin might be dry is a lot more complex. However, for a basic answer, caffeine is your culprit.
Can Iced Tea Replace Water for the Body?
Iced tea is a refreshing thirst quencher in summer for many people. And it has some health benefits. But whether or not it can replace water depends on several factors.
Iced tea is healthy, without added sugars, sodium and artificial flavors. Brewed iced tea has a lot of health benefits that make it a good substitute for water for some of your hydration needs. But don't overdo it. Watch out for the caffeine and the oxalic acid.
Food Explainer: Why Does Microwaving Water Result in Such Lousy Tea?
A reader recently wrote in to ask: Why is tea made with microwave-heated water so lousy compared to tea made with water boiled in a kettle?
Because a proper cup of black tea must be made with water that’s come to a rolling boil. A kettle is designed to heat water evenly to 212 degrees Fahrenheit. Heat at the bottom of the kettle—whether from a heating element embedded in an electric device or from a burner on the stove—creates a natural convection current: The hot water rises and the cool water falls in a cyclical fashion, which uniformly heats the contents of the kettle to a boil (at which point an electric kettle clicks off or a stovetop kettle whistles).
But microwaves don’t heat water evenly, so the boiling process is difficult to control. Microwave ovens shoot tiny waves into the liquid at random locations, causing the water molecules at those points to vibrate rapidly. If the water isn’t heated for long enough, the result is isolated pockets of very hot or boiling water amid a larger body of water that’s cooler. Such water may misleadingly exhibit signs of boiling despite not being a uniform 212 degrees. For instance, what appears to be steam rising from a mug of microwaved water is only moist vapor evaporating off the water’s surface and condensing into mist on contact with cooler air—it’s the same principle that makes our breath visible on frigid days.
Why is water temperature so important to good-tasting tea? When tea leaves meet hot water, hundreds of different compounds that contribute flavor and aroma dissolve and become suspended in the water. Black tea contains two kinds of complex phenolic molecules, also known as tannins: orange-colored theaflavins and red-brown thearubigins. These are responsible for the color and the astringent, brisk taste of brewed black tea, and they are extracted only at near-boiling temperatures.
Water also cooks certain volatile compounds, chemically altering them to produce more nuanced flavors and aromas, such as the earthy, malty, and tobacco notes in black tea. When the water isn’t hot enough to instigate these reactions and produce these bold flavors, tea tastes insipid.
Overheated water results in bad tea, too—and this is also easier to do in a microwave than in a kettle, since there’s no mechanism to indicate when the water has reached a boil. The longer water boils, the more dissolved oxygen it loses—and tea experts say that dissolved oxygen is crucial for a bright and refreshing brew. Microwaved water can also be taken to several degrees above boiling if heated for too long (which is impossible in a kettle, because the metallic surface prevents overheating). Such ultra-hot water destroys desired aromatic compounds and elicits an excess of astringent, bitter notes by overcooking the leaves. Overheated water can also accentuate naturally occurring impurities in the water that contribute off flavors to the final brew.
It’s possible that the material of the heating vessel also affects tea’s flavor. Modern day kettles are invariably made from stainless steel. While stainless steel is considered a nonreactive material, research has shown that minuscule amounts of chromium, iron, and nickel can migrate from a container or a utensil into the food. These don’t pose a safety threat, but they may well subtly affect the taste of water boiled in a kettle. In contrast, only glazed ceramics, glass, and plastics are safe to use in microwaves. It’s not inconceivable that the lack of trace metal ions are partly responsible for a lousy cup of microwave tea.
Microwaved water isn’t totally useless for all tea. In fact, water that’s microwaved to below boiling is ideal for green tea. The mellow, brothy flavors prized in green tea are mostly derived from specific savory-tasting amino acids that start to dissolve at 140 degrees. While mouth-puckering tannins are desirable in black tea, with green tea, boiling water extracts too many astringent notes and too much bitter caffeine that would overwhelm the delicate amino acids. Caffeine is extremely soluble at 212 degrees, but significantly less so at 145 to 175 degrees, the ideal temperature range for brewing green tea.
Food Explainer thanks Lou Bloomfield of the University of Virginia, Skip Rochefort of Oregon State University, and tea expert Bruce Richardson.
Unlike black tea, green tea is either steamed or pan-fired as quickly as possible after harvest to preserve its original qualities. Chinese green tea is most often pan-fired in large woks, while Japanese green tea is typically steamed in bamboo trays and each style yields a different taste. Pan-firing the leaves results in a lighter, almost toasted flavor while steaming the leaves creates a more vegetal, brisk brew. The leaves will then be rolled and dried after they’ve been heated, regardless of the method. In Japan, the most common green tea variety is Sencha, which is grown in direct sunlight and carries an astringent taste as well as near golden color, when brewed. By contrast, matcha is another Japanese green tea that is grown partially under the shade to intensify chlorophyll levels and thus, the umami, grassy taste that’s so characteristic of Japanese green tea. Popular Chinese green tea varieties include Long Jing, or Dragon Well, and Liu An Gua Pian, or Melon seed. Both taste mellow and sweet and have a light jade color when brewed, so they prove easier for blending into more complex beverages, like this sangria. Between the two countries, the main differences are that Chinese growing methods rely more on the natural terroir to impart both character and flavor, while Japanese methods are more controlled. One is not objectively better than the other, it’s simply about choosing which you enjoy.
Generally, unblended black teas are named after the region in which they are produced. Often, different regions are known for producing teas with characteristic flavors.
|Tǎnyáng-gōngfu ( 坦洋工夫 )||Tanyang Village, Fu'an, Fujian Province||The king of the Fujian Artisan Black Teas. One of the three Famous Fujian Reds.|
|Zhènghé-gōngfu ( 政和工夫 )||Zhenghe County, Fujian Province||One of the three Famous Fujian Reds, with a slight honey flavor.|
|Báilín-gōngfu ( 白琳工夫 )||Bailin Town, Fuding, Fujian Province||One of the three Famous Fujian Reds.|
|Lapsang souchong||Zhèngshān-xiǎozhǒng ( 正山小种 )||Wuyi Mountains, Fujian Province||Dried over burning pine, thereby developing a strong smoky flavor.|
|Yínjùnméi ( 银骏眉 )||A higher grade version of Zhengshan xiaozhong (aka. Lapsang Souchong)|
|Jīnjùnméi ( 金骏眉 )||One of the highest grade black teas in mainland China.|
|Keemun||Qímén-hóngchá ( 祁门红茶 )||Qimen County, Anhui Province||One of China's Famous Teas. The aroma of tea is fruity, with hints of pine, dried plum and floweriness.|
|Dianhong (Yunnan)||Yúnnán-hóngchá ( 云南红茶 ) / diānhóng ( 滇红 )||Yunnan Province||Well known for dark malty teas and golden bud teas.|
|Yingdehong||Yīngdé-hóngchá ( 英德红茶 )||Yingde, Guangdong Province||The tea has a cocoa-like aroma and a sweet aftertaste, one can find a peppery note.|
|Jiu Qu Hong Mei (Nine Winding Red Plum)||Jiǔqǔ-hóngméi ( 九曲红梅 )||Hangzhou, Zhejiang Province||This tea is characterised by tight fishhook-like leaves with a lustrous black color. The infusion is brightly reddish and has a long smooth aftertaste.|
|Taiwan||Sun Moon Lake||Rìyuè-tán-hóngchá ( 日月潭紅茶 )||Sun Moon Lake, Nantou City, Nantou County||Honey rich tones, sweet osmanthus, cinnamon and peppermint.|
|India||Assam||Ôxôm cah ( অসম চাহ )||Assam State||Full bodied, strong and distinctively malty tea from the lowlands of Assam.|
|Darjeeling||Dārjiliṁ cā ( দার্জিলিং চা )||West Bengal State||Thin bodied, floral and fruity tea from Darjeeling  with defining muscatel tones. Today often processed as a mixture of black, green and oolong elements, though still classed as black.|
|Kangra||Kāngada cāy ( कांगड़ा चाय )||Kangra District, Himachal Pradesh State||It produces basil-cinnamon, java plum-blueberry blends and Chinese hybrids that is varied with others as a pale liquor, it has a subtle pungency with a vegetal aroma. |
|Munnar||Mūnnār cāya ( മൂന്നാർ ചായ )||Munnar Town, Idukki District, Kerala State||This variety produces a strong bodied golden yellow liquor with refreshing briskness and a hint of fruit. It has a medium toned fragrance, that is akin to malted biscuits. |
|Nilgiri||Nīlakiri tēnīr ( நீலகிரி தேநீர் )||Nilgiris District, Tamil Nadu State||Intensely aromatic, strong, and fragrant tea from the Nilgiri Hills of Karnataka, Kerala and Tamil Nadu.|
|Korea||Jaekseol (Bird's tongue)||jaekseol-cha ( 작설차 )||Hadong County, South Gyeongsang Province||Jaekseol tea is golden, light scarlet in color and has a sweet, clean taste. |
|Nepal||Nepali||Nēpālī ciyā ( नेपाली चिया )||Similar to Darjeeling tea in its appearance, aroma and fruity taste, with subtle variation.|
|Sri Lanka||Ceylon||Silōn tē ( සිලෝන් තේ )||It is grown on numerous estates which vary in altitude and taste. High-grown tea is honey golden liquor and light and is considered to be among the best teas in terms of its distinct flavor, aroma, and strength. Low-grown teas are a burgundy brown liquor and stronger. Mid-grown teas are strong, rich and full-bodied.|
|Turkey||Rize||Rize çayı||Rize, Rize Province, Black Sea Region||Characterised by its strong taste, when brewed it is mahogany in color. Traditionally served with beet sugar crystals.|
|Iran||Lahijan||Chaie||Lahijan, Gilan Province, Caspian Sea (south)||Characterised by its strong taste and nice aroma, semi-long brewing time about 10–15 minutes, when brewed it is dark red in colour. Traditionally served with beet sugar crystals.|
Black tea is often blended and mixed with various other plants in order to obtain a beverage.
Masala chai has been widely recognised and adapted in the West by locals to their liking since its introduction by the British East India company, with changes in ingredients and the method of preparation to better suit western consumers.
- After the harvest, the leaves are first withered by blowing air on them.
- Then black teas are processed in either of two ways, CTC (crush, tear, curl) or orthodox. The CTC method produces leaves of fannings or dust grades that are commonly used in tea bags but also produces higher (broken leaf) grades such as BOP CTC and GFBOP CTC (see gradings below for more details). This method is efficient and effective for producing a better quality product from medium and lower quality leaves of consistently dark color. Orthodox processing is done either by machines or by hand. Hand processing is used for high quality teas. While the methods employed in orthodox processing differ by tea type, this style of processing results in the high quality loose tea sought by many connoisseurs. The tea leaves are allowed to completely oxidize.  Orthodox The withered tea leaves are heavily rolled either by hand or mechanically through the use of a cylindrical rolling table or a rotovane. The rolling table consists of a ridged table-top moving in an eccentric manner to a large hopper of tea leaves, in which the leaves are pressed down onto the table-top. The process produces a mixture of whole and broken leaves and particles which are then sorted, oxidized and dried. The rotorvane (rotovane), created by Ian McTear in 1957 can be used to replicate the orthodox process.  The rotovane consisted of an auger pushing withered tea leaves through a vane cylinder which crushes and evenly cuts the leaves, however the process is more recently superseded by the boruah continuous roller, which consists of an oscillating conical roller around the inside of a ridged cylinder.  The rotorvane can consistently duplicate broken orthodox processed black tea of even sized broken leaves, however it cannot produce whole leaf black tea.  The broken leaves and particles from the orthodox method can feed into the CTC method for further processing into fanning or dust grade teas. "Cut (or crush), tear, curl" (CTC) A production method developed by William McKercher in 1930. It is considered by some [who?] as a significantly improved method of producing black tea through the mincing of withered tea leaves.  The use of a rotovane to precut the withered tea is a common preprocessing method prior to feeding into the CTC.  CTC machines then further shred the leaves from the rotovane by passing them through several stages of contra-rotating rotors with surface patterns that cut and tear the leaves to very fine particles. 
- Next, the leaves are oxidized under controlled temperature and humidity. (This process is also called "fermentation", which is a misnomer since no actual fermentation takes place. Polyphenol oxidase is the enzyme active in the process.) The level of oxidation determines the type (or "color") of the tea with fully oxidised becoming black tea, low oxidised becoming green tea, and partially oxidised making up the various levels of oolong tea.  This can be done on the floor in batches or on a conveyor bed with air flow for proper oxidation and temperature control. Since oxidation begins at the rolling stage itself, the time between these stages is also a crucial factor in the quality of the tea however, fast processing of the tea leaves through continuous methods can effectively make this a separate step. The oxidation has an important effect on the taste of the end product,  but the amount of oxidation is not an indication of quality. Tea producers match oxidation levels to the teas they produce to give the desired end characteristics.
- Then the leaves are dried to arrest the oxidation process.
- Finally, the leaves are sorted into grades according to their sizes (whole leaf, brokens, fannings and dust), usually with the use of sieves. The tea could be further sub-graded according to other criteria.
The tea is then ready for packaging.
Black tea is usually graded on one of four scales of quality. Whole-leaf teas are the highest quality, with the best whole-leaf teas graded as "orange pekoe". After the whole-leaf teas, the scale degrades to broken leaves, fannings, then dusts. Whole-leaf teas are produced with little or no alteration to the tea leaf. This results in a finished product with a coarser texture than that of bagged teas. Whole-leaf teas are widely considered the most valuable, especially if they contain leaf tips. Broken leaves are commonly sold as medium-grade loose teas.
Smaller broken varieties may be included in tea bags. Fannings are usually small particles of tea left over from the production of larger tea varieties, but are occasionally manufactured specifically for use in bagged teas. Dusts are the finest particles of tea left over from production of the above varieties, and are often used for tea bags with very fast and harsh brews. Fannings and dusts are useful in bagged teas because the greater surface area of the many particles allows for a fast, complete diffusion of the tea into the water. Fannings and dusts usually have a darker colour, lack of sweetness, and stronger flavor when brewed.
Generally, one uses 4 grams (0.14 oz) of tea per 200 ml (7.0 imp fl oz 6.8 US fl oz) of water.  Unlike green teas, which turn bitter when brewed at higher temperatures, black tea should be steeped in water brought up to 90–95 °C. The first brew should be 60 sec., the second brew 40 sec., and the third brew 60 sec. If the tea is of high quality, it may be brewed several times by progressively adding 10 sec. to the brew time following the third infusion (note: when using a larger tea pot the ratio of tea to water will need to be adjusted to achieve similar results).
- Brew temperature 90–95 °C
- Standard [clarification needed] 200 ml water
- 4 g of tea
- Brew times [clarification needed] : 60-40-60-70-80-(+10) seconds
A cold vessel lowers the steep temperature to avoid this, always rinse the vessel with ≥90 °C (≥194 °F) water before brewing.
Whole-leaf black teas, and black teas to be served with milk or lemon, should be steeped four to five minutes.  The more delicate black teas, such as Darjeeling, should be steeped for three to four minutes. The same holds for broken leaf teas, which have more surface area and need less brewing time than whole leaves. Longer steeping times makes the tea bitter (at this point, it is referred to as being "stewed" in the UK). When the tea has brewed long enough to suit the drinker's taste, it should be strained before it is served.
The ISO Standard 3103 defines how to brew tea for tasting. 
Plain black tea without sweeteners or additives contains caffeine, but negligible quantities of calories or nutrients.  Black teas from Camellia sinensis contain polyphenols, such as flavonoids, which are under preliminary research for their potential to affect blood pressure and blood lipids as risk factors for cardiovascular disease,  but overall this research remains inconclusive. 
Black tea is also known for having various health benefits. So far scientists have concluded that they possess excellent antioxidant properties, thus they may help in decreasing the risk of chronic disease and improve your overall health. It also contains flavonoids, which are beneficial for heart health. Moreover, studies have revealed that black tea can reduce LDL levels, improve gut health & immunity, reduce the risk of stroke, lower blood sugar levels, improve focus, etc.
Long-term consumption of black tea only slightly lowered systolic and diastolic blood pressures (about 1–2 mmHg).   Black tea consumption may be associated with a reduced risk of stroke, but there is only limited research to evaluate this possibility.  
Meta-analyses of observational studies concluded that black tea consumption does not affect the development of oral cancers in Asian or Caucasian populations, esophageal cancer or prostate cancer in Asian populations, or lung cancer.    
Stay Warm with Thermal Insulation
What do you do when it gets very cold in winter? You probably turn your heater on, put on an extra layer of clothes or cuddle under a warm blanket. But have you ever thought about why a jacket helps you stay warm? Why are our clothes made from fabrics and not foils? Find out the answers in this activity your results might even help you find the best way to stay warm in the cold!
Heat is a form of energy. You need energy to heat something up: for example, a cup of tea. To make your tea you probably use energy from electricity or gas. However, once your tea is hot, it won't stay hot forever. Just leave the cup of tea out on the table for a while, and you already know that it will become cooler the longer you wait. This is due to a phenomenon called heat transfer, which is the flow of energy in the form of heat. If two objects have different temperatures, heat automatically flows from one object to the other once they are in contact. The heat energy is transferred from the hotter to the colder object. In the case of the tea, the heat of the liquid is transferred to its surrounding air, which is usually colder than the tea. Once both objects reach the same temperature, the heat transfer will stop. Heat transfer via movement of fluids (liquids or gases) is called convection.
Another type of heat transfer is conduction, in which energy moves through a substance (usually a solid) from one particle to another (unlike in convection where it&rsquos the heated matter itself that moves). A pot handle getting hot would be an example of conduction.
Heat can also be transferred through radiation. You might have experienced that from sitting around a bonfire. Although you are not touching the fire, you can feel it radiating heat in your face even if it is cold outside. If you like to drink your tea hot, you might ask how heat transfer can be reduced, and how the tea keeps from cooling down? The answer is thermal insulation. Insulation means creating a barrier between the hot and the cold object that reduces heat transfer by either reflecting thermal radiation or decreasing thermal conduction and convection from one object to the other. Depending on the material of the barrier, the insulation will be more or less effective. Barriers that conduct heat very poorly are good thermal insulators, whereas materials that conduct heat very well have a low insulating capability. In this activity, you will test which materials make good or bad thermal insulators with the help of a glass of hot water. Which material do you think will be most effective?
- Five glass jars with lids
- Scissors (and adult to help with cutting)
- Aluminum foil
- Bubble wrap
- Wool scarf or other wool clothes
- Hot tap water
- Paper for writing
- Pen or pencil
- Cut a piece of the aluminum foil, the bubble wrap and the paper (have an adult help if necessary). Each piece should be large enough to fit three times around the sides of the glass jar.
- Take the piece of aluminum foil and wrap it around the sides of one of the jars. You should have three layers of foil around the glass jar. Use the tape to attach the foil to the jar.
- Next, wrap another jar with the bubble wrap so that the glass is also covered in three layers. Make sure to tape the bubble wrap onto the jar.
- Use the cut paper to wrap a third jar in three layers of paper. Once again, attach the paper to the glass jar.
- Take another glass jar and wrap the scarf or other wool fabric around the jar. Only make three layers of wrapping and make sure that the scarf stays attached to the jar.
- Leave the last jar without any wrapping. This will be your control.
- Fill each jar with the same amount of hot water from your faucet.
- Use the thermometer to measure the temperature in each jar. Put your finger inside the water of each jar (use caution if your tap water is very hot)&mdashhow does the temperature of the water feel?
- Write down the temperature for each jar and close the lids. Are all the temperatures the same or are there differences? How big are the differences?
- Open your fridge and put all the five jars inside. Make sure they are still securely wrapped. Feel the temperature of the fridge&mdashwhat does its temperature feel like?
- Put the thermometer in the fridge. What temperature does the thermometer read when you put it into the fridge?
- Once all the jars are in the fridge, close the fridge door and set your timer to 10 minutes. What do you think will happen with the jars and the hot water during that time?
- After 10 minutes open the fridge and take all the jars outside. Do the jars feel different?
- Open each jar, one at a time, and measure the water temperature with your thermometer. Also, feel the temperature with your finger. Did the temperature change? How did it change according to the thermometer?
- Repeat measuring the temperature for each jar and write down the temperature for each wrapping material. Did the temperature in each jar change the same way? Which wrapping material resulted in the lowest temperature change, and which resulted in the biggest?
- For a better comparison, calculate the temperature difference from the beginning and end of the test for each jar (temperature beginning versus temperature after 10 minutes in fridge). From your results, can you tell which material is the best or weakest thermal insulator?
- Extra:Will temperatures continue to change in a similar way for each material? You can close each jar again and put them back into the fridge for another 10 minutes. Are the results different this time or the same?
- Extra: Does the water temperature change the same in the fridge as in the freezer or at room temperature? Repeat the test, but this time instead of putting the glass jars into the fridge, put them into the freezer or keep them at room temperature. How much does the temperature of the water change within 10 minutes? Do the different wrapping materials behave differently?
- Extra: Try to find other materials that you think are good or bad thermal insulators and test them. Which material works the best? Can you think of a reason why?
- Extra: If you take the jars out of the fridge after 10 minutes, you probably still measure a temperature difference between the water inside the jar and the temperature inside the fridge. You can keep the glass jars longer in the fridge and measure their temperature every 15 to 30 minutes. How long does it take until the temperature of the water doesn't change anymore? What is the end temperature of the water inside the glass?
- Extra: Besides choosing the right insulator material, what are other ways to improve thermal insulation? Repeat this test with only one wrapping material. This time change the thickness of your insulating layer. Do you find a correlation between thickness of insulation layer and temperature change in the fridge?
Observations and results
Did your hot water cool down significantly during the 10 minutes inside the fridge? Although the fridge temperature is very low, your hot water has a high temperature. As heat energy flows from the hot object to the cold object, the heat energy from your hot water will be transferred to the surrounding cold air inside the fridge once you put the glass jars inside. The most significant mechanism of heat transfer in this case is convection, which means that the air just next to the hot jar is warmed up by the hot water. Then, the warm air is replaced with cold air, which is also warmed up. At the same time, the cold air cools down the water inside the jar. The heat of the hot water is transported away by the flow of cold air around the cup. If you left the jars in the fridge long enough, you might have observed that the temperature changes until the hot water reaches the temperature inside the fridge. Without a temperature difference between the water and the fridge, the heat transfer will stop.
Heat from the water is also lost through conduction: the transfer of heat through the material, which is dependent on the thermal conductivity of the material itself. The glass jar can conduct heat relatively well. You notice that when you touch the glass jar with the hot water the glass feels hot as well. What effect did the different wrapping materials have? You should have noticed that with wrapping materials, the temperature of the water after 10 minutes inside the fridge was higher compared to the unwrapped control. Why? Wrapping the glass jar reduces the heat transfer from the hot water to the cold air inside the fridge. Using wrapping materials that have a very low thermal conductivity reduces the heat loss through conduction. At the same time the insulator can also disrupt or reduce the flow of cold air around the glass jar, which results in less heat loss via convection.
One way of reducing convection is creating air pockets around the jar, for example, by using insulators such as bubble wrap, fabric or wool, which have a lot of air pockets. Air in general is a good thermal insulator, but it can transmit heat through convection. However, if the air pockets inside the insulating material are separated from each other, heat flow from one air pocket to another cannot happen easily. This is the reason why you should have measured the highest temperature in the bubble-wrapped jar and fabric-wrapped jar. This also explains why most of our clothes are made of fabrics and why you stay warmer when you put on an extra jacket. Paper and foil make it easier for the heat to escape because they don't have many air pockets.
More to explore
Heat Transfer&mdashFor Kids, from Real World Physics Problems
How Animals Stay Warm with Blubber, from Scientific American
How Does a Thermos Work?(pdf), from Daily Science
Science Activity for All Ages!, from Science Buddies
This activity brought to you in partnership with Science Buddies
Difference Between Osmosis and Diffusion
Both osmosis and diffusion are examples of passive transportation wherein energy does not need to be exerted to produce an effect. Both are also a means to make the concentration of two solutions equal. Here, we will discuss how osmosis and diffusion differ from each other.
Osmosis [ edit ]
Osmosis is the process where liquid moves from a higher region of concentration to a lower region of concentration through a semipermeable membrane. Usually, the solvent or liquid involved in this process is water. Osmosis is an essential process that helps animals transport nutrients and maintain water on a cellular level, as well as help plants absorb water from the soil.
Diffusion [ edit ]
Diffusion is the movement of particles from a higher region to a lower region of concentration. These particles can be solid, liquid, or gas. Unlike osmosis, particles do not move through a semipermeable membrane. It is a faster process than osmosis, which is quite slow. Diffusion is important because it allows processes like exchange of gases when animals respire or assists in transpiration and photosynthesis for plants.
Juices, smoothies and 5 A Day
Fruit and vegetable juices and smoothies contain a variety of vitamins and minerals.
A 150ml glass of unsweetened fruit juice, vegetable juice or smoothie can count as a maximum of 1 portion of your recommended 5 daily portions of fruit and vegetables.
In other words, limit the amount of fruit juice, vegetable juice or smoothie you have to no more than a combined total of 150ml a day (1 small glass).
Have other types of fruit and vegetables for the other 4 (or more) portions.
This is because the sugars in fruit and vegetables are released when they're juiced or blended, making them "free sugars".
Once released, these sugars can damage your teeth, especially if you drink juice or smoothies often.
The sugars found naturally in whole fruit and vegetables are less likely to cause tooth decay because the sugar is contained within the structure of the fruit.
It's best to drink juice or smoothies with a meal because this helps reduce harm to your teeth.
Biological means the washing powder formula uses enzymes as a way of achieving a really deep down clean. This almost certainly means that you can wash at lower temperatures and with less water to achieve a really deep down clean. Different enzymes are suitable for different applications and fabrics. Lipase enzyme, for example, being more suitable as a degreaser, and others more general purpose or for removing particular dirt types such as the effect protease has on the protein molecules in foodstuffs.
Enzymes have a particular lock and key action, which you may remember from biology lessons and they take a particular catalyst to start them off. In our case, this is both heat reaching the 30/40 degree point and the effect of the other ingredients as they dissolve to create a certain alkalinity level in the wash. The agents we use to achieve this process also aids the water softening meaning you need less detergent to achieve an effective clean with Distinctive.
The protease enzyme, one of the components in Distinctive, is great at breaking down the proteins in food stains, body waste such as urine, feces and semen, some fats, blood and other naturally occurring everyday grime that we get on our clothes.
Distinctive’s superior formula means you won’t need any additional products when you wash. You don’t need to buy a fabric softener, as we have in-built cationic softening, (explained above), and unless you have a particular stain, such as an oil mark, you won’t ever need a stain remover either. If you notice a deep set food or mud stain then just pre-soak overnight with a little Distinctive in cool water before washing.
If you have tired old whites then a whitener product added occasionally to an all-white load will work wonders and is better than a costly accident damaging expensive bedding or clothing if you use a laundry product that has a whitening effect.
Sensitive skins really are no more likely to react to a bio, as a non-bio, but there is no reason for the big players in the washing industry to re-educate the public, as they have bios and non-bios on the shelves.
A bio product can contain optical brighteners (UV dyes that reflect light and make a product appear whiter than it is) or it can be without. Optical brighteners are great for whites as you can imagine, but they leave a permanent change as a build up on a coloured or delicate item that makes it look a little faded and patchy as if the item has aged very quickly. You’ll see the UV speckles on other peoples clothing, (like dandruff) if you are under strobe lights.
Some washing formulas will also contain harsh bleaching agents – again, ours doesn’t for a reason, we want to look after mixed and expensive designer fibers in one easy washing load.
New Laundry powders in Europe have to be compliant with being fully biodegradable and phosphate free (2015 Laundry regulations).
In Distinctive Washing powder all of our surfactants, (washing chemicals) are 100% environmental. It is something we are super proud of!
Phenolic Compounds in Coffee Compared to Other Beverages
Mauricio A. Rostagno , . Maria Angela A. Meireles , in Coffee in Health and Disease Prevention , 2015
15.3.2 Oolong Tea (Semifermented) and Black Tea (Fermented)
The oxidative process of fermentation refers to the enzymatic browning reactions induced by the enzyme polyphenol oxidase that acts on the leaf cells. This process is important for the development of flavor, color, and aroma as well as for influencing the phenolics content present in tea. 24–26 The difference between the oolong tea and black tea is the different oxidative process that leads to the transformation of flavan-3-ols to theaflavins (TFs) and thearubigins (TRs) in green tea. 27 As the oxidative process takes place, EGCG, ECG, EGC, and EC contents decrease and theaflavin and thearubigin contents increase. The catechins EGCG, ECG, EGC, and EC correspond to 30–50% solids in green tea extract and 10% in black tea extract, and the theaflavins (3–6%) and thearubigins (10–30%) are predominant in black tea and responsible for the bitter taste and dark color of the beverage. 28
The effects of the antioxidant activity (AA) depend mainly on the variety of tea and on EGCG concentration. Both green tea and oolong tea have higher EGCG and EGC contents than black tea. The AA of catechins, evaluated by the diphenylpicrylhydrazyl method, depends on its structure according to the following order: EGCG > ECG > EGC > EC > C. 29,30
What are flotsam and jetsam?
Marine debris washed ashore in Kaho'olawe, Hawaii.
You may have heard of 'flotsam and jetsam' from the movies, but do you know the meaning of the words? While the phrase 'flotsam and jetsam' is often used to describe 'odds and ends,' each word has a specific meaning under maritime law.
Flotsam and jetsam are terms that describe two types of marine debris associated with vessels. Flotsam is defined as debris in the water that was not deliberately thrown overboard, often as a result from a shipwreck or accident. Jetsam describes debris that was deliberately thrown overboard by a crew of a ship in distress, most often to lighten the ship's load. The word flotsam derives from the French word floter, to float. Jetsam is a shortened word for jettison.
Under maritime law the distinction is important. Flotsam may be claimed by the original owner, whereas jetsam may be claimed as property of whoever discovers it. If the jetsam is valuable, the discoverer may collect proceeds received though the sale of the salvaged objects.
NOAA's Marine Debris Program's mission is to investigate and remove problems that stem from marine debris to protect and conserve our nation's marine environment, natural resources, industries, economy, and people. Marine debris is defined as any persistent solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment or the Great Lakes.
A majority of the trash and debris that covers our beaches and floats in our ocean comes from storm drains and sewers, as well as from shoreline and recreational activities such as picnicking and beachgoing. Abandoned or discarded fishing gear is also a major problem because this trash can entangle, injure, maim, and drown marine wildlife and damage property.