Sunday, 10 October 2010

Green Engineering: Self-Cleaning NanoTechnology

Green Engineering: Self-Cleaning NanoTechnology

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Sunday, 10 October 2010
Dedicated to David Suzuki, and THRC's Green Technical Textile Knowledge Network Initiative.
Nature has nurtured our environment with abundance of resources and green energy. Can we harvest, harness and sustain these free energy to foster innovative solutions to clean our environment?  Yes, we can. How? Imagine a green engineering solution to clean air-pollution to foster a sustainable clean environment. Imagine a truly textile substrate, integrated with green nanomaterial, keeps cleaning air and environment to provide us comfort and quality lifestyle that we envision.
Plant's chlorophyll, a typical natural photocatalyst, captures sunlight to turn water (H2O) and carbon dioxide (CO2) into oxygen (O2) and glucose. On the contrary in the presence of light and water, photocatalyst nTiO2, creates strong oxidation agent and electronic holes to breakdown the organic matter to CO2 and H2O as shown in figure..
Chemical Reactions:
  • Reduction Reaction: O2+e- O2- Superoxide anion
  • Oxidation Reaction: H2O+h+ -OH Hydroxyl radical
Disinfections by nTiO2 is x3 stronger than Cl2 & x1.5 stronger than O3
Wavelength of light required for Photo-excitation ʎ  =Planck’s Constant, h:1240/Band Gap Energy: 3.2eV = 388nm
Research reveals that bacteria, molds and mites inside carpets and air conditioners can be airborne - dust particles, paints, varnishes and pressed wood products used in interior decoration, form formaldehyde, benzene and other hazardous and carcinogenic chemicals as well as matters produced in human metabolism and ammonia inside toilets have made the indoor air severely polluted than the outdoor air. 
Usually people spend about 80-90% of their time indoors. They are exposed to polluted indoor air that may cause headaches, dizziness, irritation, fatigue and even lung cancer and other malignancies. Scientists have been modifying materials and offering creative solutions to these challenging problems.
TiO2 Crystal Structures:
  1. Rutile: Tetragonal crystal system, Band gap: 3.0eV. Less reduction power. More stable at high temperature. Density: 4.2743. UV resistance. Blocks  sunlight
  2. Anatase: Tetragonal crystal system, Band gap: 3.2eV. More reduction power. More stable at low temperature. Density: 3.895. Photocatalyst
  3. Brookite: Density: 4.123
  • Self-cleaning
  • Air purification
  • Anti-bacterial, Anti-fungi, and Anti-mold
  • Super hydrophilicity
  • Antistatic surface
  • UV resistance
  • Easy-cleaning
  • Keeps the surface clean
  • Purifies air pollutants e.g. VOCs, NOx, Formaldehyde, Benzene
  • Decomposes bacteria and virus on the surface and in the air
  • Restrains growing mildew, mold, fungi, or algae
  • Decomposes the organic pollutants on the surface
  • Protects the surface from dust, dirt and air pollutant damage
  • Absorbs UV rays from sun and protects the surface from UV damage 
Self-Cleaning Mechanism:
Toxic VOC + Light + H2O + TiO2 = Non-Toxic Inorganic Gas + TiO2
  • Micro-organisms carry '–ve' charge.
  • nTiO2 surfaces carry '+ve' charge.
  • Photo-excitation
  • ElectroMagnetic Attraction
  • Oxidation
  • Decomposition

Click on the links below for in-depth information. Explore and enjoy!

Green Engineering: Self-Cleaning NanoTechnology

Interesting Links:
Featured Insights:
2010 Self-Cleaning Coatings, P A Carpentier, K D Burgess, WO/210/078649, PCT/CA2010/000009, Jul 15
2010 Extreme Engineered Materials Design, S Islam, Textile,, Jul10
2010 Super Strong NanoCrystalline Cellulose Synthesis: Challenges and Opportunities, S Islam, Nanotechnology,, Jul 04
2010 Progress and Perspectives in the Carbon Nanotube World, M Endo,, Jun 23
2009 Nanoparticles Used in Common Household Items Cause Genetic Damage in Mice, Science Daily, Nov 17
2007 Boiactive Silk Proteins as Geotextile Substrates, M Tsukada, S Islam, Y Ishiguro, Textiles & Clothing, Jan-Mar 5-6
2006 Methods and apparatus for spinning spider silk protein, S Islam et al., USP 7,057,023 Jun 6
2005 TiO2 Photocatalysis: A Historical Overview and Future Prospects, K Hashimoto, H Irie, A Fujishima, Japanese Journal of Applied Physics, Vol. 44, No. 12, 8269-8285
2005 Value-added Textile Technology, S Islam, Textile Excellence J., Anniversary Issue, Jul. 3(1) 55-56
2005 Photocatalyst technology adds value to fabric, K Tagawa, Fabric Architechture, May
2005 Titanium dioxide photocatalysis: present situation and future approaches, A Fujishima, X Zhang, Elsevier, Feb 2, 750-760
2004 Enhancing Sorption Properties of Natural Fibrous Protein Substrates.   Part I: Absorption of malodorous gases, M Tsukada, H Katoh, S Islam, N Kasai, Text. J., 121(6) 48-50
2004 Antibiotic Silk Substrates for Healthcare, M Tsukada, G Shen, S Islam, Text. J. 121(5) 47-49
2003 Process of producing a titanium oxide-forming solution and a dispersion with crystalline titanium oxide particles, I Hiromichi, USP 6,602,918, Aug 5
2002 Photocatalytic body and method for making same, I Hiromichi, USP 6,429,169, Aug 6
1999 Suppression of Surface Recombination on TiO2 Anatase Photocatalysts in Aqueous Solutions Containing Alcohol, O A Semenikhin, V E Kazarinov, L Jiang, K Hashimoto, A Fujishima, American Chemical Society, May 06, 3731-3737
Picture Credit: courtesy of
Stay tuned. More to come....
Acknowledgements: TexTek Solutions :: MW Canada Material Innovations.  

সৌজন্যেTexTek Solutions ::  Vision Creates Value

শফিউল ইসলাম
ইমেইল: :: ওয়েবঃ :: Canada ::     
সর্বশেষ আপডেট ( Wednesday, 08 February 2012 )

Green Engineering: Self-Cleaning NanoTechnology:

প্রবচনগুচ্ছ - গোলাম মোস্তফা

বুঝে পড়ে দেখিলাম করি তালিকা
সবচেয়ে সুমধুর ছোট শালিকা ।

মোটা পণ লালসায় মন ভরোনা
শালী যেথা নেই সেথা বিয়ে করোনা ।

♪ ♫ ♪


গোলাম মোস্তফা

Wednesday, 6 October 2010

Rima’s Letter

Mizan Rahman

  There was a letter from home yesterday. It was my niece Rima, daughter of a younger brother of mine. She is very concerned about this old uncle of hers. Concerned that I am not taking good care of my health. In her mind everybody is too busy fussing over the poor health of my wife to pay any attention to mine. So she feels obligated to write to me from time to time, mostly to admonish me, then to remind me about all my “do’s”  and “don’ts”. Must drink a glass of freshly squeezed orange juice everyday, must eat a slice of Jamaican papaya with your breakfast, and a good portion of a grapefruit. You must never go near that salt shaker, and no oil but the purest of pure olive oil. And yes, don’t forget to say your prayers everyday, 5 times a day, and never, ever forget your daily exercises. Quite a taskmaster, this niece of mine. And she is not even my own daughter! I wonder what kind of torture I would have to suffer if she were. Would I be able to take so much motherly admonition from her?
  Writing letters has gone out of fashion these days. It has gone the way telegrams and ‘trunk-calls’ have gone. Everyone sends e-mails or ‘text-messages’. Electronic device, mostly. Even important documents are no longer put in the mail, they are either faxed or scan-mailed. It’s the modern age, defined and dominated by technology. No country, rich or poor, large or small is any exception---the phenomenon is global. It’s a global village, as the slogan says. That includes our own country, Bangladesh. We may not have enough food to eat, but that doesn’t hold us back from owning a cell phone and/or accessing a computer to send an e-mail to someone we care for. On paper Bangladesh is not too far behind the emerging superpowers like India and China. On paper!
  Except these two children of the low-income brother of mine. As well as the children of a sister who is equally deprived of many of the niceties of life. They do not have computers in their house, not even a mobile telephone. Can’t afford one. Essential food items gobble up most of their take-home earnings. At the end of almost every month they are forced to take a loan to run the rest of the month, just to survive. They do not have any disposable income to spend on luxury items like a computer----yes, computer is a luxury item for them. Just like my childhood, when we didn’t have running water in our house, nor electricity, nor telephone, fridge or a radio. What we used to do is come home from school, grab a cookie or two from my mother’s cookie jar, drink a glass of water, or a glass of milk if lucky, then run off to play soccer with friends in the neighborhood field. Then came home, took a cold bath in an uncovered bath area, say my prayer, ate a simple meal, then got down for homework. My brothers and sisters, 4 or 5 of them, all cramped up at the same table, reading our books as loud as possible to make sure they are well within the hearing range of our parents. On the table we had just one dimly lit kerosene lamp to share among all of us. These will surely sound like horror stories to the children of today’s electronic age. Nowadays my relatives’ children commute on the family car back and forth to school. Back home in the afternoon they relax in the TV room with plateful servings of  puris and pakurahs and jilebis. Perhaps they turn the A/C on and lean back on the soft sofas for a quick nap. Or pick up the cell to call a friend when they get bored. Oh, that abominable thing called cellphone, that ubiquitous cell, the greatest equalizer of modern life! Is there a Bangladeshi family that doesn’t own at least one cell, I wonder.
  Most school children don’t rush out to the fields as soon as the classes are over, as we did. Where are the fields anyway? They too have vanished. Like the old typewriter or the fountain pen or the sewing machine. Besides, whom will they play with? ‘Neighborhood boys’ do not mean quite the same thing as before. The phrase usually refers to the hoodlums, the goons, the ruffians, or worse. They are constantly prowling the streets looking for ‘hits’, for ‘preys’. Neighborhoods are always tense with mortal fear of these ‘neighborhood boys’. People don’t usually let their children out alone after school. They just sit tight in the house with shuttered windows and locked doors. Their children play monopoly in the house, the video games, or just do nothing. I don’t know when they do their homework, or if they do at all. Many of them, especially the ones from relatively affluent families go to the coaching classes or to the teachers’ homes. Seems like the good old custom of reading at the top of your voice has gone out the window. The only thing they still read aloud, and will probably do till eternity, is the Holy Quran.
   Except the family of this brother of mine. Mainly because they do not have a car---can’t afford one. Rima doesn’t play video games because she can’t----there are no facilities. Every morning she takes her meal with plenty of rice and vegetable curry with one or two pieces of a burbot. Then she goes to the university on a rickshaw. She carries her books and papers on her lap along with a small brown bag that her mother packs with a few cookies or a piece of cake for her afternoon snack. At lunch break her class mates go out in chauffer driven cars to their homes or nearby Chinese restaurants, while she finds herself a corner in the back of the common room to gobble up her snack before the other girls get back from their lunch. She is too proud to let anyone see what is inside her ‘lunch-bag’. In the evening her nervously waiting mother breathes a sigh of relief when her daughter’s face appears at the door----one more day has passed without a trouble. No Bangladeshi mother these days can relax while her 20-yr old daughter is out of the house. Especially the girls who have to go to schools or colleges on rickshaws or scooters.  They worry all day until they are back home safely----mostly because of those ‘neighborhood boys’ roaming the streets looking for easy preys like Rima. These animals will think nothing of destroying an innocent girl’s life for their own momentary pleasure. Or to tear off her earlobe to snatch the pair of earrings, or to take off with whatever little cash she might be carrying in her purse. Slightest resistance from her could easily result in a knife in the stomach or the blades of a sharp razor in her throat. These lowly creatures never get caught by the police, or if they do, get released just as quickly thanks to a telephone call from one of their powerful godfathers.
    My brother works at a local bank. Manager of a branch office. Monthly salary: seventeen thousand takas. In my mind I think of 1958 when I first joined the Dept. of Mathematics as a senior lecturer with a princely salary of 450 takas. Compared to that my brother should be living like a king. Except that time has changed. In 1958 ten takas were enough for the daily grocery of a family of 10 adults-----now it takes 500 for a single midsize fish! The biggest price tag is on the rent—it can easily gobble up close to half of your monthly income. They live in a tiny 2-bedroom apt. in a dark alley of a lousy area called Siddeswari. Their apt. is on the 4th floor. The stairs to the apt. are always in a filthy condition, no lights whatsoever, it’s pitch dark even before the sun has actually gone down. Could you guess how much they pay for it? Not one, not two, but as much as seven thousand! Seven thousand for a dark hole in a rat infested alley! Per month, of course. I had to mention this lest you thought it’s per year. Before I actually landed in Dhaka I had all the intention of sharing my time with all my siblings----at least one night each. But as soon as I entered their apt. I got a real shock---no, it’s impossible. I can’t stay here, even for a night. Not just the filth and stink, but a whole army of insects having taken the entire family hostage. Swarms of mosquitoes milling around me in a blatant attempt at carrying me up to their den for a communal feast. Admittedly each room had a large window, but unfortunately they were all closed securely from inside. I wondered, naively, why on earth they would do that in broad daylight in a 4th floor apt. where the break-in possibility was almost nonexistent. I got the answer. The fear was not of the thieves but of the eyes. What eyes, I asked innocently, like a 12-yr old child. The eyes of an evil character next door, they said. You can’t open the windows without his dirty eyes prying into your privacy. He will sing cheap songs from the Hindi movies, make obscene gestures, throw love letters through the window. Not always, of course, only when Rima is in her room. In the olden days you could complain to his parents, or to the neighborhood elders, maybe even to the police. But those days are gone. The boy, apparently is involved in the politics of Students’ League---- a fearful band of gangsters who are well-protected by their sponsors upstairs. Today they are the guardians, they are the neighborhood elders, they are the police. If Rima’s father is foolish enough to ask for legal protection perhaps it will be the daughter who will be picked up for questioning. Yes, it was this very neighborhood where that hapless young man Rubel used to live. For absolutely no fault of his own he was beaten to death by the police, then the body cast aside by the street in the dark of night. If it is not the fear of police it is the fear of acid. Yes, acid, that burns, maims, or kills. Acid is so callously and regularly used by the spurned lovers bent on taking revenge (if I can’t have you I’ll make sure nobody will) -----mostly done by the well-connected student leaders. They will not bat an eyelid to burn a girl’s face and destroy her entire life in a fraction of a second. Ordinary citizens are now resigned to their fate. No use calling for help----there’s no help but the help of God in this godless land. This probably explains why the average Bangladeshis seem to be much more religious than they ever used to be.
   I guess it is common knowledge by now how a young girl called Bnadhan was disrobed publicly by a mob on the open fields of the University of Dhaka. It happened right after the day I arrived in Dhaka. It was the front page news in the local newspapers complete with gory photographs of the poor girl, a very juicy, saucy piece of news that everybody loves to read and reads to hate, that helps raise the sale of the paper and provides ample ammunition to the gossip mongers. The national leaders were quick to come out with statements of condemnation for the unfortunate incident. The Home Minister made a promise to apprehend the culprits as soon as possible and bring them to justice. Even the uniformed police came forward with their own promise of not resting until the criminals are arrested. The University President joined the chorus of condemnation, expressing “deep regret” for this dastardly act having happened on the premises of his venerable institution. He didn’t forget, however, to add a conciliatory remark to the student body, that he would never believe that the guilty boys could be students from his University. Too bad that the same day the news broke out that one of the perpetrators of the despicable act was none other than a prominent student leader, very well-connected with the high and mighty, and of  the higher echelon of the ruling party, and was indeed from his venerable campus. Apparently he was identified by the victim herself. But nobody in his/her right mind believes that the young man will ever be brought to justice, let alone punished for his crime. No one in Bangladesh today has the guts to ask for punishment of a student leader, no matter what the crime is. I couldn’t find a single person who really believed that the law would be able to, or even try to, touch the scoundrel. Money and political influence can buy anything today. Law and Order is just a slogan that is routine bread and butter of every Opposition Party. Law exists there not to be obeyed but to be broken. And they are broken mostly by the law-makers themselves. Cabinet, Legislative bodies, Ministers, Bureaucrats, Police---- there’s no exception. People laugh when you combine the two words: Law and Order. What a joke, they say. Or they think it’s a quote from a prepared speech.

   Such is the sickening atmosphere of cynicism in my country today.
   The sick game of pulling a girl’s dress has been such an old culture in our society that I get surprised when someone expresses outrage and revulsion when something like that does actually happen----our young men have always had a strange fascination with this game. Young women have always been an object of amusement and pleasure for the men folk. No matter how much we idolize them through poetry, no matter how passionately we profess our solidarity with their demands for equal rights, in our eyes fundamentally they remain little more than sex objects----something to stoke our fantasies. In the olden days this hidden desire would find expression in a more civilized and subtle manner, but now it is all so open, and often so brazenly aggressive. Wasn’t only the last year when a bunch of policemen got hold of a young girl and undressed  her publicly in broad daylight? There were the usual herd of eager correspondents from the tabloids and newspapers salivating on the delicious scene and taking pictures for the morning editions, while the greedy eyes of a crowd of onlookers swallowed up every tiny bit of her bare flesh. I don’t know why such disgusting things are happening so regularly these days. Could it be because of a twisted sense of freedom and openness derived from the nation’s political independence?  I talked to a number of well-educated people about this unpleasant incident and asked for their opinion. Would you believe no one was willing to put the blame on those offending boys, rather they quite emphatically placed the blame on the victim for failing to exercise prudence before showing up in a crowd like that in less than ‘an appropriately modest’ attire. According to them she asked for trouble by simply being there. So she got what she deserved----no point complaining about it now. The comments came from no less than the people who live in fashionable houses in exclusive areas of Banani, Gulshan and Baridhara, whose grown children have left home for higher education in  prestigious colleges of Europe and America. And, women outnumbered men in their vocal denunciation of the “outrageous” behavior of that “shameless” girl in the streets. These are the ladies with highest degrees from the country’s best colleges. So why should it surprise you if the culture of vulgar amusement and entertainment is perpetuated till the end of time in that godforsaken land of ours?
  There is no denying that women have a great deal more opportunity these days to get an education in Bangladesh compared to what it used to be in the olden days. Not just the girls from relatively well-off families but from the utterly poor ones also. One of the housemaids in the household of a sister of mine apparently has a daughter doing postgraduate work in Statistics. In my own native village I saw the daughters of my cousins no longer thrashing paddy on the wooden pedals or picking cucumbers from the fields, rather riding the rickshaws every morning to their classes in the nearby college. They become doctors, engineers, teachers, lawyers, or nurses. Some even make careers as architects, pharmacists, physiotherapists and hairdressers. So one can indeed claim, at least on paper, that the country has moved forward in very impressive ways compared to what it used to be in the pre-independence time.
  And yet, I couldn’t find a single girl riding a bike on the street, or even driving a car. Not but a handful of women without a head cover, called hijab, some even with full nikab, covering their whole bodies. These so-called modesty dresses for Muslim women that have become such a common sight in the streets of Dhaka nowadays were not quite as common in our days, which I find very curious and puzzling. In my student days in Dhaka I didn’t even know the meaning of the word hijab. It simply didn’t exist in our vocabulary. It is not a Bengali word. Yet, today, the word is part of our common vocabulary. In my time I never heard of a woman being flogged or stoned on charges of adultery or other sex-related offenses, but now the deadly fatwa is always ready to strike the poor woman. One fatwa is enough to destroy a woman’s life for good-----she will have nowhere to go, not even her parent’s home. In the bygone days the girls wouldn’t usually go for higher degrees ( because there used to be a widespread social taboo against Muslim women’s higher education, most of them being married off at 16 or 17), but they wouldn’t be victims of acid-throwing either. Compared to the times before independence the incidence of rape and abduction has increased manifold, dowry murder has become a common thing. Daughters had never been a major concern for Bangladeshi Muslim parents, but now they are. A daughter usually means dowry, often unbearably large dowry. As a result the number of unmarried daughters has greatly increased in Muslim families these days, especially those with little means to eke out a half decent living. The chauffer of my sister’s car had a newborn baby girl. As I was trying to congratulate him on the happy news he sighed, and said: “ Sir, what’s the point of getting congratulations? What I need is fifty thousand takas. If I could keep that amount of money in the bank then I could get the girl married. “
  I had the good fortune of being a dinner guest of a highly educated and culturally accomplished middle class family at their residence in a densely populated neighborhood of Dhaka. They were 2 older brothers and 4 sisters. The sisters were all very good-looking, well-educated, and well-mannered. Quite attractive, I would say. And yet they were all unmarried----all but one having already crossed the age of 30. And there didn’t seem to be a hopeful sign that the situation would change anytime soon. Why?  First, even though their father was a senior bureaucrat in his working days, was now retired. More importantly, he had one serious flaw! He was an honest officer! Honesty is indeed a character flaw, a weakness, in Bangladeshi society these days. Which explains why he couldn’t acquire large chunks of property in posh areas of Dhaka as most other officers, even the ones at lower ranks than him, have been able to do.  Which is why at retirement he had to be content with a modest home in a rundown building in a decrepit part of the town. Today it is his daughters who are paying the price of his “clean” living and his unwavering principle of integrity.
   There is no way I can guarantee that my brother himself has clean hands, as far as corruption is concerned. However, when I see that after 25 years of active service in a major bank of Dhaka he still doesn’t own a car, nor has a glittering home in a fashionable area of the city, I feel reasonably confident that it was his deliberate choice to stay away from that slippery path that so many of his contemporaries seem unable to avoid. Maybe this is what explains this pathetic state of his life in a filthy area with dark alleys where the sun never seems to rise. Maybe this is why his only daughter, his princess, the pearl of his eye, has to take the risky way every day taking a rickshaw to attend her classes at the university. And his only son has no choice but walk every day to his not-too-close school.
   I feel real bad for Rima. Foolishly I asked her if she had a dream. Of course she had. How silly of me to even ask. Every child has a dream. Especially a child from an impoverished family. Dreams are the only escape they have from the miseries of life, their only bit of reprieve. Nobody can take that away from them---it is their birthright. In my youth I too had a lot of dreams which I never shared with anyone----they were strictly my own property, my only property. I’m sure my 4 younger sisters had their own dreams which they dared not share with anybody for fear of being laughed away. But I always knew what they wanted from life. They just wanted a normal life, a life where they would have a choice, choice to pursue their goals, to get the highest degree from the best university in town, and then, maybe, just maybe, meet their prince charming on the way, to be desired, adored and cherished.  If not a prince at least a top officer in the government. None of those lofty dreams really came true in their life, they never really do, so they had to settle for whatever fate had ordained for them. In countries like ours’, girls’ dreams almost never ever come true. Yet dreams are important. They help deal with the daily grind and drudgeries of life. They are a source of hope, light and joy.
   Rima wrote: “ You know uncle, I was bit upset with you that you didn’t spend a single night at our home. In fact I was quite sulky. But not anymore. The world you live in has completely different set of rules, and norms, I know. But sometimes, at weak moments, I let myself forget that. That’s why I sulk, I feel sad. Please don’t mind, uncle. The few days you were in Dhaka somehow felt different, as if my life had changed a little. I felt as if there was a bit of fresh breeze in the air. But then you went away. Without your knowing that breeze also went with you. Our life is now back to normal.
  Maybe this is her dream---a dream for a bit of fresh air. Perhaps she doesn’t fancy a prince charming from the fairy tales like my sisters used to, nor does she dare to hope for a top civil servant. Maybe all she wants is to be able to keep her windows open at all times. And to be able to let her wet hair hang lazily to her knees in the open space of the roof, to soak up the afternoon sun in cold wintry days, to leisurely button up her blouse with no concern for anyone stealing a look, or to sing away her favorite songs in great abandon. Or could it be that her only dream is to escape to the fairy land called North America, like her uncle had done?  Perhaps all she dreams about is to be able to go a place where there are no strikes, no coaching classes, no postponing the exams, no murders, or purse snatching or mugging or brazen attempt at disrobing a fun-loving innocent girl on the new year’s eve. Maybe she even dreams to ride a bike like the western girls do, to swim in a pool, to buy her favorite nuts from the street vendor and start eating while walking with friends.
  I do not know if I really understood the meaning of Rima’s letter. Perhaps not. Perhaps all she was trying to tell me: uncle, I can’t breathe anymore. Would you please take me away from this hell? 

October 6,’10
( Translated from the author’s Bengali article by the same title written and published in February, 2,000).

মীজান রহমান, 
Mizan Rahman