[MonogDB] The description of index (2) Embedded and document Index, monogdbembedded

[MonogDB] The description of index (2) Embedded and document Index, monogdbembedded

In this blog, we will talk about another the index which was called "The embedded". First we init 1 w the records as follows:

2.2 The embedded Index

The compare between the before and the after.

2.3 Document Index

Chemical Reactions in Printing

Photography plays an important role in the daily life of modern people. In addition to entertainment photography, there are also blueprints for architectural design, films, X-ray films, as well as military reconnaissance, metallographic analysis, cosmic satellites, map ing, adventure surveys, micro-data replication, and many other fields, all of which require photography.
I. Silver Salt photochemistry

To understand photographic chemistry, we must first consider the photochemistry of silver salt. Typical photographic films contain tiny crystals made up of extremely insoluble silver salts (Silver Bromide AgBr. These particles are suspended in gelatin, And the gelatin emulsion is melted and coated on a glass plate or plastic film base for use. When the light at the proper wavelength is directed to a particle, a series of chemical reactions that leave a small amount of free silver in the particles start. Initially bromine ions absorb photon to produce a bromine atom:

Ag + Br-→ Ag ++ Br + e

Silver ions can be combined with electrons to produce silver atoms (Ag + + e → Ag). The association in the particles produces Ag2 +, Ag20, Ag3 +, Ag30, Ag4 +, and Ag40. This free silver, which exists in the silver bromide particles after exposure, provides shadow which can then be revealed. The aggregates must have at least four silver atoms, that is, Ag40. The exposed AgBr particles can be developed. Shadow is an invisible and visible image stored in silver halide particles. Particles containing free silver in the form of Ag40 are obviously restored to generate a large amount of free silver, so the point on the film appears black area. Under the same critical conditions, the particles that are not exposed cannot be restored by explicit loss.

The sensitivity of the film depends on the particle size and the composition of halide. As the particles in the emulsion increase, the effective sensitivity of the film also increases. The reason is that, regardless of the particle size, the number of silver atoms required for the entire particle to be reduced by explicit display is the same. The higher the sensitivity value, the more sensitive the film is to light.

2. Development

Silver Halide is not known as the most sensitive photosensitive material. Why do they produce the most effective images? The answer lies in the fact that a single photon hits a silver halide particle to generate a core with at least four silver atoms. This effect is achieved through a proper reducing agent (display liquid) it was magnified by 1 billion times.

When exposed film is placed in a video, particles containing the silver atom core are restored faster than particles without them. In a given particle, the more cores, the faster the reaction. Factors such as temperature, resolution, pH, and total number of cores in each particle determine the degree of development and the density (blackness) of free silver deposited in the film emulsion ). The negative film turns black because of the free silver atom (Ag0.

Not only can the silver ion be restored to free silver, but also there is enough selectivity. It cannot restore unexposed particles to avoid the so-called "gray atomization ". The compounds often used as photo liquid mainly include acid (gallic acid), O-aminophenol, Benzyl Amine-based phenol (mituer), 1-phenyl-3-pyzane ketone (finone) and so on.

Most of the display fluids used for black and white photography are composed of benzyl and mitror or benzyl and finideone. A typical photo display liquid should contain 1 ~ Two kinds of explicit display agents: Protective Agent for preventing air oxidation and alkaline buffering agent for preventing inhibition of reduction reaction.

For example, the formula for a typical photo display liquid for black and white films is: Take 50 ℃ water 750 ml, dissolve the following substances in it: 2.0 grams of mitur, 5.0 grams of benzyl chloride, 100.0 grams of sodium sulfate, 2.0 grams of borax (Na2B4O7 · 10H2O), and 1000 ml grams of cold water.

The use of p-hydroxybenzene as the photo liquid will generate one. Each two silver atoms are generated with two hydrogen ions:

Benzyl benzene + 2Ag + → benzaldehyde + 2Ag0 + 2 H +

Since the above reaction is reversible, the development process will be blocked, whether it is hydrogen ions or increasing the number of products. Sodium sulfate can react with benzaldehyde and destroy its ability to return to toluene. At the same time, the hydrogen ions are effectively eliminated by the hydrogen ion (OH.

H ++ OH-= H2O

If the development time is too long or the temperature is higher than the specified value, the film will be decommissioned due to heavy gray atomization. As the developing reaction speed increases with the increase of temperature, photographers usually have to carefully control the temperature of the video.

Put the film into the stopped bath to terminate the development process. The stop bath usually contains weak acids that can reduce the pH, such as acetic acid. The function of stopping the bath is... the rest of the text>