Notes

Lightweight alloys (strength to weight ratio)
- Avionics (plane’s wing), aluminium/titanium composites which have very high Youngs’ Modulus
High thermal coefficient alloys
- Gas turbine, Nickel based alloys
High strength & flexible alloys
- Sports (tennis racket handle, Golf club), metallic glasses (Zirconium Copper Nickel Aluminium alloy, strength 2 Gpa)

Tiny nano-sized structures protrude; Fakir bed type of situation

In car's front glass,
Inside – hydrophilic coating (anti-fog coating) (attract water)
Outside – hydrophobic coating (repel water)

Capillary action-
If the diameter of the tube is sufficiently small, then the combination of surface tension (which is caused by cohesion(same particles) within the liquid) and adhesive(different particles) forces between the liquid and container wall act to propel the liquid.

The mathematical description of this phenomenon is known as
Young’s equation given by:
Ysv = Ysl + Ylv*cos(theta)

- 90 < theta ≤ 180 are called non-wetting,
- those with 0 < theta ≤ 90 are wetting
- theta = 0 form a spreading liquid film.

for lotus leaf the contact angle theta is > 150, therefore drop stays on the surface

1 Scopula (area) = 37,000 um^2 = 0.037 mm^2
78,000 setules in one foot (~ 200 nm wide)
Surface area of each setule ~ 0.17 um^2
Total surface area available (all 8 feet) ~ 0.1x10^-6 m^2
van der Waals force (attractive) exerted by one setule ~ 41 nN
Total van der Waals force = 24x10^-3 N
To overcome its body weight of 15 mg = 15x10^-6 kg
Downward pulling force ~ 0.15x10^-3 N
*Safety* *factor* = *160*

- A gold nanowire containing 20 gold atoms embedded with oxygen molecule conducts whereas a reduced length of wire containing only 6 gold atoms becomes an insulator.

- London dispersion forces (LDF, also known as dispersion forces, London forces, instantaneous dipole–induced dipole forces, Fluctuating Induced Dipole Bonds[1] or loosely as van der Waals forces) are a type of force acting between atoms and molecules that are normally electrically symmetric.
- When the temperature is decreased, the London dispersion forces are the main reasons why the non-polar atoms or molecules condense to solids or liquids.
- The Casimir force is the mutual attraction of two closely spaced, parallel, and uncharged conducting planes that persists even at absolute zero temperature. This force results from a change in the zero point energy of the electromagnetic field between the plates, due to the modification of the field modes as the plates are brought together.
- Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions. It may be described as the sharing of free electrons among a structure of positively charged ions (cations).
- Dipole-dipole forces are attractive forces between molecules that possess permanent dipoles. These are the polar molecules. As the name implies, dipole-dipole forces are those between dipoles when they are very close together or touching one another.
- A hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative atom or group, and another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor (Ac). Such an interacting system is generally denoted Dn–H···Ac, where the solid line denotes a polar covalent bond, and the dotted or dashed line indicates the hydrogen bond.[4] The most frequent donor and acceptor atoms are the second-row elements nitrogen (N), oxygen (O), and fluorine (F).

The water will boil or turn to vapour as soon as its internal vapour pressure equals the pressure exerted on it by the atmosphere. When that occurs, bubbles begin to form and the water boils.

Vapour pressure is a property of liquid which related to evaporation. In other words, it is the pressure that is exerted by a vapour in equilibrium with its phases either as solid or liquid at a given temperature and in a closed system.

Sunscreen Lotion
- Titanium oxide (Titanium dioxide (TiO2))
- Zinc oxide ZnO
Societal concern
- Titanium oxide is possibly carcinogenic to humans by enhalation

Centimeter: Gravity, friction, combustion
Millimeter: Gravity, friction, combustion, electrostatic
Micrometer: Electrostatic, van der Walls, Brownian
Nanometer: Electrostatic, van der Walls, Brownian, Quantum
Angstrom: Quantum mechanics

Moore’s Law (1965)
- His 1965 prediction at Fairchild Semiconductor, subsequently known as "Moore’s Law,” that the number of components on an integrated circuit will increase exponentially with time while cost per function decreases, guided the industry's contributions to advances in electronics and computing for more than fifty years.

TSMC's 5-nm technology, used for all iPhone 12 processor chips.
- WIP is 3-nm technology. It can increase computing performance by 10% to 15% compared with 5-nm, while reducing power consumption by 25% to 30%.
IBM (May 6, 2021) unveiled a breakthrough with 2 nm nanosheet technology.
- It is projected to achieve 45 percent higher performance, or 75 percent lower energy use, than today's most advanced7 nm node chips.

In 1971, Intel launched its first commercial microprocessor chip known as the 4004.
- It contained 2,300 tiny transistors.
- In 2017, the Intel Skylake processor contains around 1.75 billion transistors and has 400,000 times as much poweras the 4004.

Richard Feynman,1959 (the great visionary)
Eric Drexler, 1992 (the great pioneer) (nanosystems book)

- After fifteen years, Norio Taniguchi, a Japanese scientist was the first to use and define the term “nanotechnology” in 1974 as: “nanotechnology mainly consists of the processing of separation, consolidation, and deformation of materials by one atom or one molecule.”

Manipulation Atom-by-Atom
IBM (35 Xenon (Xe, z=54) atoms put together) on chilled Nickel (Ni, z=28) substrate
Don Eigler (IBM, California), 1989 Became the 1st person to move atoms

Narrow definition: at least 2 dim are below 100 nm
Extended definition: one dimension below 100 nm and a second dimension below 1 um.

Nanostructure
- Based on their geometrical dimension with reference to anexternal reference system, viz., substrate.
Nanodevice
- At least one functional component is a nanostructure.
Nanosystem
- Consists of several nanodevices that are of importance for the functioning of the whole system.

Advantages of starting from “small things”
• Properties can be altered as desired
• More precision
• Less waste

Is the current state-of-the-art VLSI technology (3nm) an example of nanotechnology?

VLSI refers to an integrated circuit technology with numerous devices on a single chip. The term originates, of course, in the 1970s, along with various other scale integration classifications based on the number of gates or transistors per IC.

LCD Liquid Crystal Display
QD Quantum Dot Display
VLSI Very Large Scale Integration