Why does shape memory alloy have memory ability?
It starts with its microstructure. When a metal is solid, its atoms are always arranged in a regular way, forming a lattice. Under different conditions, such as temperature, metal may have a different structure, in which case it is said to be in a different phase. The change from one phase to another is called a phase transition. The properties of a metal change during a phase transition. The temperature at which a metal transforms is called the transition temperature. The difference between a shape memory alloy and other metals is that the phase transformation process in a shape memory alloy is reversible under certain conditions.
The extraction of titanium
Nowadays, the commonly used extraction method is the reduction method of titanium tetrachloride. Compared to copper and zinc, although high in content, much more expensive. On the other hand, China is the country with the largest reserves of titanium, and a large number of steel mills with perennial overcapacity began to produce titanium, so the price of titanium fell year after year.
How to Wear Cat Eye Glasses?
Since the cat eye frame glasses are so popular, you may ask whether I can wear the cat eye glasses. Usually, cat eye glasses can suit a variety of face shapes. But faces with more angular or prominent features would look best in a round or oval shaped pair of cat eye glasses because these cat eye frame glasses will balance wide jawlines of square or triangle faces, while the rounded lens will soften sharp features.
However, the round face will look best in frames which are with bold and angular lines. These striking details will help to sharpen soft facial features and rounded jawlines. You can click here to know more knowledge of the face shape and how to choose the glasses frames.
Target Optical
Target Optical provides easy eye care. They both deliver on the promise of expect more, pay less, combining high-quality eye care, fashion, affordability, and a simple, fun shopping experience. You can always get more for less. There are popular contact lens brands like Acuvue、CIBA and Specialty Glasses.No matter what you choose, there is an unconditional warranty.
What is a qualified plano lens?
First, identify the surface. High-quality products should not have obvious scratches, pitting, edge collapse, sand holes, water ripples, bubbles, and other surface defects. Put glasses next to the place of 33 cm or so at the moment. When looking at the object through glasses, there is no phenomenon that the objects become big or decrescent, and you should not have a feeling that the objects are beating. Otherwise, the quality of the glasses has a problem. Next check through the instrument identification. Finally, check whether the trademark, manufacturer, and quality certificate are true and reliable. The lens of the international famous brand product is often engraved with the manufacturer's trademark, which can be found by careful observation on the edge of the lens.
What Is Progressive Lens?
Progressive lenses, also called multifocal lenses, have three prescriptions in one pair of glasses. So, it allows you to see near, middle distance, and far objects without changing your glasses. The progressive lenses are designed for people who are over 40 years old who are both nearsighted and farsighted. The progressive lenses come with the following features:
- There is no distinct line between all visions(near, intermediate, and far).
- Most popular lens for anyone with presbyopia who wears
- Expanded intermediate zone for better computer vision.
From the above information, you may have known the differences between bifocal lenses and progressive lenses. As for progressive vs bifocal lenses, which one is better? It is difficult to judge because each of them has unique features. So, if you do not know choose which, you can listen to the eye doctor.
Blue light in electronic products
In addition to the blue light that exists in natural light, LED energy-saving lamps, fluorescent lamps, computer monitors, mobile phones, and other digital products will emit blue light because of the use of light-emitting diode LED technology. Some people think that blue light hurts the eyes because blue light is not absorbed by the cornea and lens like ultraviolet light. The blue light can pass through the refractive medium of the eye to reach the retina, and then be absorbed by the pigment epithelium of the retina, which will cause aging and functional degradation of the retina over time.
The eyes also have many protection mechanisms, such as squinting, pupil contraction, lutein contained in the macula of the retina, and the retina's own antioxidant repair mechanism, which protect our eyes from blue light damage. And after scientific testing, it is found that the blue light emitted by electronic products is only several hundredths of the intensity of blue light in natural light. This means that as long as the electronic products are not used continuously every day (for example, more than 8-10 hours a day), the blue light will not cause obvious damage to the eyes.
