The Journal of the American Institute for Conservation (JAIC) is an international peer-reviewed periodical for the art conservation profession. The Journal publishes articles on treatment case studies, current issues, materials research, and technical analyses relating to the conservation and preservation of historic and cultural works. The topics encompass a broad range of specialties including architectural materials, archeological objects, books and paper, ethnographic materials, objects, paintings, photographic materials, sculpture, and wooden artifacts. Started as the Bulletin of the International Institute for Conservation-American Group (IIC-AG), in April 1961, the Journal matured into its current form in 1977. Since that time JAIC has become a repository for the core body of conservation information through its documentation of new materials, changing methods, and developing standards in the conservation profession. The four-color publication is distributed three times a year to AIC members and museum, library, and university subscribers.
We know that there are a lot of suspended organisms and colloidal impurities in natural water. The forms of suspended solids are different. Some large particles of suspended solids can settle under their own gravity. The other is colloidal particles, which is an important reason for the turbidity of water. Colloidal particles can not be removed by natural settlement, because colloidal particles in water are mainly clay with negative electricity The Brownian motion of colloidal particles and the hydration on the surface of colloidal particles make colloidal particles have dispersion stability. Among them, electrostatic repulsion has the greatest influence. If coagulant is added to water, it can provide a large number of positive ions and accelerate the coagulation and precipitation of colloid. Compressing the diffusion layer of micelles makes the potential change into an unstable factor, which is also conducive to the adsorption and condensation of micelles. The water molecules in the hydrated film have fixed contact with the colloidal particles and have high elastic viscosity. It is necessary to overcome the special resistance to expel these water molecules. This resistance hinders the direct contact of the colloidal particles. The existence of some hydrated films depends on the electric double layer state. If coagulant is added to reduce the zeta potential, the hydration may be weakened. The polymer materials formed after coagulant hydrolysis (the polymer materials directly added into water generally have chain structure) play an adsorption bridging role between the colloidal particles. Even if the zeta potential does not decrease or does not decrease much, the colloidal particles can not contact each other and can be adsorbed through the polymer chain Colloidal particles can also form flocs.
It’s true that titanium dioxide does not rank as high for UVA protection as zinc oxide, it ends up being a small difference (think about it like being 10 years old versus 10 years and 3 months old). This is not easily understood in terms of other factors affecting how sunscreen actives perform (such as the base formula), so many, including some dermatologists, assume that zinc oxide is superior to titanium dioxide for UVA protection. When carefully formulated, titanium dioxide provides excellent UVA protection. Its UVA protection peak is lower than that of zinc oxide, but both continue to provide protection throughout the UVA range for the same amount of time.
By September, demand in the construction sector had significantly increased; however, resurgent cases of virus hindered the anticipated recovery in demand. However, due to a severe fall in market fundamentals in some end-use areas, its prices had significantly faded by quarter-end. Delays in a number of commercial projects, followed by a poor recovery in the downstream automotive market, were identified as primary causes of the protracted recovery curve.
At present, Lide powder is mainly produced in China. Most of the domestic Lide powder production is still using traditional methods. The main raw materials are zinc oxide, sulfuric acid and barium sulfide (barite and coal are produced by high temperature reduction). Zinc 45% ~ 70%. The traditional method for producing the Liede powder process is to use zinc bakelite containing more than 45% zinc as a raw material to be leached with sulfuric acid to obtain a crude zinc sulfate solution, and then to remove iron by potassium permanganate, and then replace the heavy metal with zinc powder and filter to obtain zinc sulfate. The refined liquid is further subjected to metathesis reaction, pressure filtration, calcination, rinsing, drying, and pulverization with strontium sulfide to obtain a series of different types of lindose powder containing zinc sulfide of 30% or more. The whole process is carried out in an acidic (ra<7) environment, which consumes a large amount of sulfuric acid. The sulfuric acid has strong corrosiveness and requires high production equipment. The final discharged slag is acidic slag, which brings new pollution to the environment. High requirements, high production costs, and poor quality of the products obtained.
For instance, fluctuations in the price of zinc oxide and sulfur, key components in lithopone, directly impact the final price list For instance, fluctuations in the price of zinc oxide and sulfur, key components in lithopone, directly impact the final price list
