Science, Art, Litt, Science based Art & Science Communication

My answers to questions on science -4

Q: Why does it feel very sultry when it rains in summer?

Krishna: :)

When I was very young, a person gave this answer to this Q when I asked him - when it rains in the summer all the heat in the Earth comes out and the rain is not sufficient to cool it down. So you sweat more! Hmmm! This is only a partial picture.

Now, of course, I know the right answer to give to people who ask this very Q.

Okay, like all my answers it starts with "science".

And "evaporation". Our body produces sweat to help keep us cool during the summer heat, but that only works if the sweat evaporates, because evaporation is a cooling process. So when the relative humidity of the air is high because of the rain, meaning the air has a high moisture content, the sweat evaporation process slows down.

When the relative humidity (water in the air), increases, your body's natural cooling system, sweating, becomes less effective. Your body sweats water which is supposed to evaporate, cooling you. If the air is saturated with water already, your sweat does not evaporate. Thus you get hotter.

The result? It feels hotter to you. The opposite occurs if the air is very dry. Even on a 100 degree day, it can feel a little cooler to the body if the air is dry because sweat evaporates quickly.

This is the same reason why it feels very sultry near sea shore or any huge water body.

Why is it so humid before it rains in the summer?

Humidity is where the rain comes from. As a warm and humid parcel of air lifts into the upper troposphere and lower stratosphere, the humidity condenses on solid particles in the air. When enough humidity condenses on a single particle, a raindrop is formed. When enough raindrops form, it rains. As to why exactly, during summer, the jet-stream(s) are usually at higher latitudes. This allows moisture to move from lower latitudes to higher ones. When humidity condenses, it releases latent heat. This warms the upper troposphere and lower stratosphere and the rain cools the lower troposphere. This rebalances the heat in the atmosphere.

Q: What if a HIV infected person talks with us and by talking, his saliva with blood gets into our mouth?

Krishna

Image source: ResearchGate.

You can’t transmit HIV through saliva.

Even kissing doesn’t transmit HIV but very rarely, transmission occurs if people have sores or bleeding gums. Saliva carries very small traces of the virus, but this isn’t considered harmful. Saliva contains enzymes that break down the virus before it can spread.

HIV doesn’t spread through saliva or the air. HIV can’t be contracted or spread through CPR.

Through the air: HIV doesn’t spread through the air like a cold or flu virus. So, HIV can’t be transmitted if someone with it speaks, sneezes, coughs, laughs, or breathes nearby. If a person living with HIV spits in food or drinks, there’s no risk of transmitting HIV because saliva doesn’t transmit the virus.

HIV can spread only through certain bodily fluids and only if the person interacting with HIV has a detectable viral load in their system. These fluids include: blood, semen, vaginal fluid, anal fluid, and breast milk.

It can’t be transmitted through saliva, sweat, skin, feces, or urine.

So, there’s no risk of getting HIV from regular social contact, such as talking, closed-mouth kissing, shaking hands, sharing drinks, or hugging, because those bodily fluids which can transmit HIV aren’t exchanged during these activities.

The most common way to acquire HIV is through sex, including oral, vaginal, and anal sex, without a condom or other barrier method if the person living with HIV has a detectable viral load. HIV can also be transmitted by sharing needles with someone living with HIV who has a detectable viral load.

Pregnant people living with HIV can transmit the virus to their child during pregnancy, vaginal delivery, and breastfeeding. But many people living with HIV have healthy, HIV-negative babies with good prenatal care. Treatment for HIV (antiretroviral therapy, or ART) substantially reduces the risk of perinatal transmission.

Oral transmission of human immunodeficiency virus (HIV) by the millions of HIV-infected individuals is a “rare event”, even when infected blood and exudate is present. Saliva of viremic individuals usually contains only noninfectious components of HIV indicating virus breakdown in the saliva.

Why is HIV rarely transmitted by oral secretions? Saliva can disrupt orally shed, infected leukocytes.

Research results showed these things (1):

Saliva rapidly disrupts 90% or more of blood mononuclear leukocytes and other cultured cells. Concomitantly, there ‘s a 10000-fold or higher inhibition of the multiplication of HIV and surrogate viruses. Further experiments indicated that the cell disruption is due to the hypotonicity* of saliva:

Conclusions: Hypotonic disruption may be a major mechanism by which saliva kills infected mononuclear leukocytes and prevents their attachment to mucosal epithelial cells and production of infectious HIV, thereby preventing transmission. Implications for the known oral HIV transmission by milk and seminal fluid, as well as potential oral transmission to contacts and health care workers, are considered.

So, don’t worry about talking with a HIV positive person.

Footnotes:

Why is HIV rarely transmitted by oral secretions? Saliva can disrup...

*having an osmotic pressure lower than that of an isotonic solution. Saliva is always hypotonic to plasma.

-----

Q: MEDICAL DOCTORS ONLY, PLEASE: Is Dana Scully's character (The X-Files) realistic in that, having never practiced, she can answer the most specific questions on everything? Seems only a specialist could do that, in each field.

Krishna: I am not a medical doctor but answering this question anyway because I can relate to this.

I didn’t even watch the acting of Dana Scully until now because I don’t get time to watch TV.

But know who she is. She is a special agent and a medical doctor in the X-Files.

The writers write the stories after researching on the issues and the actors act their part.

The story has to be shown realistically and therefore, she has to be shown as an intelligent agent cum medical doctor.

You said “Never practised”. If she is a qualified and trained doctor, she must have got most of her knowledge through her studies and training. If she gets updated on recent work very frequently , she can have tremendous knowledge.

I am a microbiologist. I never ‘practised’ in other scientific fields. But I can answer questions in several fields of science because as a science communicator, I learn several things in several subjects to communicate research papers in those subjects efficiently. As I deal with original research papers my knowledge is highly authentic. Even medical doctors say they are getting updated through my write ups.

I am an artist, I can create art works, and though I never got any degree in art, I researched in art and published papers too in peer reviewed art journals.

I am a writer and write articles, stories, poems.

I can also do several other things in several fields like people in those fields.

How?

If you really want to learn things and know how to get accurate information on any subject, nothing can stop you.

You can master as many fields as you want. There is no limitation.

Only things required are the right mindset to do tremendous hard work, knowing the correct way of getting the right knowledge and an unlimited thirst for it.

So this Dana Scully might have learnt several things out of interest. This is not surprising at all. Not unrealistic too. Well anyway, the writer is doing good research work to make the character look brilliant.

This is neither impossible nor unrealistic, although it looks odd because you don’t find such people very frequently. But they do exist!

(Let me also tell you something you don’t know. If you get a very positive impression about a person /character , you think all that the person is saying is brilliant, even if it is not. Even simple things the person says gives an ‘expertise picture’ unless you yourself are an expert, you can’t tell the difference. People use this trick to get away with ‘ordinary knowledge’. ‘Illusion of knowledge’ applies to others’ knowledge too!)

Still do you think some people are really brilliant? Well, that is your headache!

----

Q: How does ironing them makes the clothes wrinkle free?

Krishna: The wrinkles in natural cotton cloth material come down to the chemistry of plant-based fabrics. Cotton, linen, hemp, and so on are predominantly made of cellulose, a polymer that consists of thousands of glucose molecules joined together to form linear chains. Each glucose subunit is “sticky” because it can bind to neighbouring cellulose molecules via hydrogen bonds. Individually, these bonds are very weak, but together they form a network that gives the fabric its strength.

These hydrogen bonds are forever breaking and then rapidly reforming. As a result, clothes start taking on the shape that they are left in. As they sit there in a pile, the bonds break and reform, the clothes take up the new shape of the fabric, and the creases are set in place.

Things get even worse when water enters the equation (while washing). Water molecules insert themselves between the cellulose molecules, break up the hydrogen bonds, and act as a lubricant, allowing the cellulose molecules to slide over one another. Then, when the fabric dries, the cotton keeps its now-wrinkled shape.

This is where the hot, steaming iron comes in. The combination of heat and moisture quickly breaks the hydrogen bonds. As you apply these with a bit of pressure, all the cellulose molecules are forced to lie parallel with one another, thereby flattening the cloth.

Alternately, you could go with the age-old practice of starching your clothes to keep them crease free. This works because starch is also a polymer made from glucose, so it too can form all those sticky hydrogen bonds. But unlike cellulose, starch is a branched polymer, so it sticks and acts as a scaffolding to hold all the cellulose molecules in place. The drawback is that starch is soluble, so it just comes out in the wash.

---

Q: What Makes a Fabric Wrinkle Resistant?

Krishna: A fabric’s tendency to wrinkle – or not wrinkle – depends on several factors. Typically, weight, weave complexity, composition, and treatment (if any) dictate the level of a fabric’s wrinkle resistance. As a general rule, the more weight, the more treatment, and the more complex the weave construction, the more resistant to wrinkling it will be, and vice versa. Several of these factors are often at play in a single fabric, and certain combinations can help increase a fabric’s wrinkle resistance.

A fabric’s weave type can dictate its natural wrinkle resistance. More visibly pronounced weaves like royal oxfords, imperial twills, and jacquards will tend to wrinkle less, whereas broadcloth (or poplin) and plain weave fabrics with a very smooth, flat appearance will tend to wrinkle more.

Weave density plays a further role. The diagonal line weave of twills is particularly dense, so they will often resist wrinkles better than oxfords and pinpoints of similar weights. Oxfords and pinpoints, with their “dot” weave construction, are less dense and have slightly “looser” and more “open” structures, and are therefore less wrinkle resistant. Broadcloth is more difficult to weave with a very high density, so most broadcloths will tend to weigh less than twills, oxfords, and pinpoints. Broadcloth is therefore among the most wrinkle-prone dress shirt fabrics.

The material from which a shirt is made will also affect its wrinkle resistance. Shirts with wool woven into them resist wrinkles very well, while 100% linen or cotton/linen blends are naturally more wrinkle-prone. Fabrics made from synthetic materials with inherent resilience, like nylon and spandex, are very wrinkle resistant as well.

And a fabric may be chemically treated to help it resist wrinkles. Treatments range in strength, from “wrinkle -resistant” — meaning the fabric will need to be ironed or steamed after washing, but will hold up well against wrinkling throughout a day of wear — to “non-iron”. Non-iron fabrics have a stronger treatment that prevents them from needing to be ironed or steamed post-wash. If they’re hung to dry, they’ll be ready for wear immediately, and daily activity will hardly cause them to wrinkle at all. Fabrics that do not have these extra treatments generally cannot be expected to perform as well, though there are some exceptions, such as merino wool fabrics, which need no treatment in order to stay completely wrinkle-free.

---

Q: How does water cause obesity?

Krishna: While there's a common misconception that drinking too much water can make you gain weight, in fact, the opposite is true. Water can help you lose weight and maintain a healthy weight. Staying properly hydrated helps maintain a healthy metabolic rate, allowing the body to convert food into energy efficiently.

Researchers have tried to find out the effect of drinking excessive water in female overweight participants, in terms of weight loss (1). The decrease in body weight, BMI, sum of skinfold thickness, and appetite score of overweight participants at the end of study period establishes the role of drinking excessive water in weight reduction, body fat reduction, and appetite suppression of participants. Thus, water drinking induced increase in sympathetic activity is an important and unrecognized component of daily energy expenditure. If confirmed in future studies with larger number of subjects, this cost free intervention may be a useful adjunctive treatment in overweight and obese individuals to attain an increase in energy expenditure.

Water is your body's principal chemical component, making up, on average, 60% of your body weight. Every system in your body depends on water. For example, water flushes toxins out of vital organs, carries nutrients to your cells and provides a moist environment for ear, nose and throat tissues. Lack of water can lead to dehydration, a condition that occurs when you don't have enough water in your body to carry out normal functions. Even mild dehydration can drain your energy and make you tired.

By drinking more water per day, you will have a series of weight gains throughout the day as a quart (32 ounces) of water weighs two pounds. But you also lose it through the process of excretion . The easy answer is yes; drinking water affects weight significantly enough to be seen on a scale immediately. Usually, in a 24-hour period, you will cycle through this process of gaining water weight and losing water weight and have either a net loss or stable weight for the day, depending on your consumption and excretion.

Humans sweat, digest, and breathe. All three processes help our bodies to expel water.