وبلاگ شیمی - زندگی - سلامت wellcome to my weblog

سان توضیح می‌دهد که موقعی که آب در سرتاسر لایه‌ی انتخابی غشاء اسمز پیش‌رو نفوذ می‌کند، محلول کشیده شده در طرف خروجی بسیار رقیق می‌شود. بنابراین به دلیل رقیق بودن مواد حل‌شونده در طرف خروجی، نفوذ به عقب باعث کشیده شده مواد حل‌شونده درسرتاسر لایه پایه می‌شود. این فرآیند به سختی بوسیله لایه‌های پایه‌ی ضخیم و متراکمِ غشاءهای مرسوم اسمز پیش‌رو به تاخیر می‌افتد. نفوذ مواد حل‌شونده به دو طرف در یک غلظت به تعادل می‌رسد. این محدودیت منجر به مشکل قطبش غلظت داخلی (ICP) می‌شود.

سان توضیح می‌دهد که یک لایه پایه‌ی ایده‌آل غشاء اسمز پیش‌رو، علاوه بر جلوگیری از مشکل ICP باید جهت عبور آسان آب، یک ساختار بسیار نازک و بشدت متخلخل داشته باشد.

سان می‌گوید: "ما یک غشاء اسمز پیش‌رو نانوکامپوزیتی جدیدی ساخته‌ایم که یک لایه پایه‌ی نانوالیافی شبه داربستی دارد که در مقایسه با لایه‌های پایه‌ی شبه اسفنجی مرسوم مزیت‌هایی از قبیل تخلخل بالا، ضخامت بسیار نازک و پیچیدگی کم، دارد. این ساختار بی‌نظیر لایه پایه‌ی نانوالیافی، مسیرهای مستقیمی برای نفوذ آب و نمک تهیه می‌کند که می‌تواند برای جلوگیری از مشکل ICP راه‌حل خوبی ارائه کند".

این گروه تحقیقاتی جهت ساخت غشاء‌ اسمز پیش‌رو نانوکامپوزیتی خود از فرآیند الکتروریسندگی استفاده کرد و برای اولین بار یک ماتریس نانوالیافی متخلخل بعنوان یک لایه پایه، تولید کرد.

این محققان جزئیات نتایج کار تحقیقاتی خود را در مجله‌ی Advanced Materials منتشر کرده‌اند.

http://www.nanowerk.com/spotlight/spotid=21857.php

عبارت است از:
دستکاری کوچکترین اجزاء ماده یا اتم‌ها

1. Merriam-Webster"s Collegiate Dictionary
2. Engines of Creation
3. The About.com
4. Webopedia"s definition of nanotechnology
5. Whatisit.com
6. NNI)nano.gov)

Merriam-Webster"s Collegiate Dictionary definition:
nano•tech•nol•o•gy
Pronunciation: "na-nO-tek-"nä-l&-jE
Function: noun
Date: 1987
: the art of manipulating materials on an atomic or molecular scale especially to build microscopic devices (as robots).

Engines of Creation Glossary:
Nanotechnology - technology based on the manipulation of individual atoms and molecules to build structures to complex, atomic specifications.

The About.com definition at the physics portal:
Nanotechnology Definition: The development and use of devices that have a size of only a few nanometres. Research has been carried out into very small components, which depend on electronic effects and may involve movement of a countable number of electrons in their action. Such devices would act faster than larger components. Considerable interest has been shown in the production of structures on a molecular level by suitable sequences of chemical reactions. It is also possible to manipulate individual atoms on surfaces using a variant of the atomic force microscope.

Webopedia"s definition of nanotechnology A field of science whose goal is to control individual atoms and molecules to create computer chips and other devices that are thousands of times smaller than current technologies permit. Current manufacturing processes use lithography to imprint circuits on semiconductor materials. While lithography has improved dramatically over the last two decades -- to the point where some manufacturing plants can produce circuits smaller than one micron (1,000 nanometers) -- it still deals with aggregates of millions of atoms. It is widely believed that lithography is quickly approaching its physical limits. To continue reducing the size of semiconductors, new technologies that juggle individual atoms will be necessary. This is the realm of nanotechnology.Although research in this field dates back to Richard P. Feynman"s classic talk in 1959, the term nanotechnology was first coined by K. Eric Drexler in 1986 in the book Engines of Creation.In the popular press, the term nanotechnology is sometimes used to refer to any sub-micron process, including lithography. Because of this, many scientists are beginning to use the term molecular nanotechnology when talking about true nanotechnology at the molecular level.

Whatisit.com definition: Nanotechnology, or, as it is sometimes called, molecular manufacturing, is a branch of engineering that deals with the design and manufacture of extremely small electronic circuits and mechanical devices built at the molecular level of matter. The Institute of Nanotechnology in the U.K. expresses it as "science and technology where dimensions and tolerances in the range of 0.1 nanometer (nm) to 100 nm play a critical role." Nanotechnology is often discussed together with micro-electromechanical systems (MEMS), a subject that usually includes nanotechnology but may also include technologies higher than the molecular level. (click the link for entire definition)

NNI definition
National Nanotechnology Initiative (nano.gov)

What is Nanotechnology?
While many definitions for nanotechnology exist, the NNI calls it "nanotechnology" only if it involves all of the following:

1. Research and technology development at the atomic, molecular or macromolecular levels, in the length scale of approximately 1 - 100 nanometer range.

2. Creating and using structures, devices and systems that have novel properties and functions because of their small and/or intermediate size.

3. Ability to control or manipulate on the atomic scale.