China 
Africa 
Explore chapters and articles related to this topic
Optical Thin-Film Coatings
Published in Paul Klocek, Handbook of Infrared Optical Materials, 2017
In general, the best coatings are made using the best starting material. Certainly, high purity is desirable. Purity is typically stated as a percent (e.g., 99.99% or “four 9s”). Designations of this type rarely indicate the absolute purity of the material but rather the difference from 100% and the total of a limited number of other possible impurities for which the lot has been tested. Four 9s pure ThF4 probably contains no more than 0.01% rare earth metals but might contain a higher percentage of oxygen. A specific analysis is required where absolute high purity is required or where there are known contaminants that cannot be tolerated (i.e., soluble salts such as NaCl and KCl and water). Thin-film coating materials for most routine work are specified as vacuum-annealed or vacuum-deposition grade materials. Materials can also be purchased in a wide range of forms such as powder, granular, pressed pellets, crystalline, chunks, wire, and even vacuum-pressed specialty shapes for sputtering targets and E-gun pockets.
Biomanufacture
Published in John M. Centanni, Michael J. Roy, Biotechnology Operations, 2016
John M. Centanni, Michael J. Roy
Both quantity and quality of a BS matter greatly to the manufacturer. Quality control test results of BS must demonstrate that product, at this stage, possesses all intended attributes. In Chapter 7, we will discuss the tests used to measure those attributes. Each test is classified under the attribute it measures: identity, safety, purity, and potency. Purity is of particular importance, because it is a key objective of downstream processing. However, in a general sense, how do we define purity of a molecule such as a recombinant protein? One guideline often applied to biopharmaceuticals is that more than 95% of the BS is the intended and intact ingredient and less than 5% of the BS are the known or unknown impurities and contaminants. Most biomanufacturing operations strive for more than 98% or greater purity, certainly for commercial manufacture. However, there are caveats to this purity guideline. First, the balance of material in BS, the remaining 2% or 5% if you will, must be known, indeed be characterized, for it cannot be toxic or allergenic or potentially toxic to the user and it must consist of various materials without a predominant molecular entity: impurity or contaminant. Second, it is not always possible to reach the 95% purity level, and in such instances, it may be acceptable to identify impurities and show that they cannot be harmful to the product or the user.
Distillation
Published in John J. McKetta, Unit Operations Handbook, 2018
Specifications on product quality may be set in terms of purity, component impurities, or both. These purity or impurity specifications may be expressed in mole (gas-volume) percent, weight percent, or liquid-volume percent, depending on the tradition within the industry using the product. If the product is sold in the gaseous state, such as natural gas and nitrogen, it is accounted in volumetric units of both quantity and purity. Most chemical products are sold in mass units, and therefore the concentrations of components they contain are given in weight percent. Liquid petroleum products are typically sold by the barrel or gallon, and therefore their purities are reported in liquid-volume percent.
Double layer lanthanide –Pt/TiO2 nanotube arrays electrode as a cost-highly efficient electrocatalyst for hydrogen evolution in acid media
Published in Journal of Experimental Nanoscience, 2021
Khadijah M. Emran, Hessah E. Alanazi
The anodization of titanium metal to generate nanostructured TiO2 has been achieved using the experimental rig described schematically in Figure 1(a). The system developed includes an electrochemical cell, a power supply capable of operation as a voltage source (Germany, PeakTech, 6005D)/current measuring device (US & Canada, Agilent digit multimeter, 34450A). The cell was designed to be made in a 100 mL Teflon beaker. At the anode, a titanium sheet (Alfa Aesar, purity 99.5%) having an area of approximately 1 cm2 was left exposed to the electrolyte. Platinum wire (Alfa Aesar, purity 99.95%) was used as a cathode. Figure 2 shows the anodization synthesizing of undoped TNTAs in a non-aqueous solution containing small amount of a fluoride salt. In the first-step anodization, TNTAs were prepared at applied voltage of 60 V for I h. After ultrasonic removal of the of performed TNTAs layer, the nano concaves Ti substrate was the second-step anodizing at 60 V for 1 h. Nd-Pt-TNTAs, Gd-Pt-TNTAs, Nd-Gd-Pt-TNTAs and Pt-TNTAs were prepared by the hydrothermal method. The as prepared anodized TNTAs were immersed into 30 mL different doped solution, 10:1 of Nd(NO3)3:PtCl4, Gd(NO3)3:PtCl4, [Gd(NO3)3+ Nd(NO3)3]:PtCl4, (Sigma Aldrich, purity 99.9%), in a Teflon-lined stainless steel autoclave and kept at 180 °C for 2 h as shown in Figure 1(b). After cooling to the room temperature, the sample was removed from autoclave, rinsed with deionized water and finally dried in air.
Study on the metakaolin-based geopolymer pervious concrete (MKGPC) and its removal capability of heavy metal ions
Published in International Journal of Pavement Engineering, 2021
Xiao Chen, Zidong Niu, Haoyu Zhang, Yuguang Guo, Min Liu, Mingkai Zhou
The metakaolin (MK) was prepared by calcination of kaolin at 800°C for 4 h and was used as aluminosilicate material for MKG.The chemical and mineral compositions of MK are shown in Table 1 and Figure 2. The alkaline activator was prepared using sodium silicate (Na2SiO3•3.2H2O; purity, 34%) and sodium hydroxide (NaOH; purity, 96%). β-Al2O3 (purity, 99.9wt%; fineness, <50 μm) and silica fume (SF, purity, 93.7%; fineness, <10 μml) were used to adjust the ratio of MKG. Three different particle size ranges of limestone gravel (2.36–4.75 mm, the apparent density is 2.72g/cm3; 4.75–9.5 mm, the apparent density is 2.76g/cm3; 9.5–13.2 mm, the apparent density is 2.69g/cm3) were used to adjust the graduation and the stacked void ratio of aggregate, with physical properties of aggregates shown in Table 2. PbCl2 and CrCl3•6H2O (chemical purity) were used to prepare the heavy metal ions solution, with the concentrations of Pb2+ and Cr3+ fixed at 60μg/L, which were similar to concentrations of heavy metal ions in rainwater according to (Reimann et al. 1997). In order to simulate rainwater (Reimann et al. 1997, Abulude and Akinnusotu et al. 2016) and eliminate the effect of pH of solution on the adsorption of heavy metal ions on MKGPC, the pH of this solution was adjusted to around 6 by adding dilute nitric acid.
Real-time monitoring of order-disorder transformation of FePt thin films by light scattering
Published in Journal of the Chinese Institute of Engineers, 2021
H. C. Fan, Fu-Te Yuan, H. W. Chang, Chi-Yang Shen
The thickness of underlayer Au, FePt, and coverlayer Au are 80 nm, 60 nm, and 60 nm, respectively. The trilayer films are deposited at ambient temperature by radio frequency (RF) magnetron sputtering in argon atmosphere of 10 mtorr in pressure on a Corning 1737 glass substrate. The background vacuum is better than 10−6 torr. The trilayer samples were prepared by batches, so that the samples in the following experiment, with different heating temperatures, had consistent chemical composition and thickness. Gold layers were deposited using a high purity (99.99 at%) gold target. FePt layer was deposited by using a stoichiometry FePt alloying target, and the composition of the thin films were further confirmed by inductively coupled plasma (ICP) technique to be Fe50.4Pt49.6. Surface morphology was analyzed by atomic force microscopy, AFM, within area of 500 nm × 500 nm with scan rate of about 1 Hz. Root-mean-square roughness was determined by averaging roughness values from 10 AFM images for every single sample. Evolution of crystal structure and lattice parameters were analyzed by X-ray diffractometry (XRD) using θ-2θ scan mode with slow scan rate of 0.1°/min. The wavelength is 1.54056 Å (Cu Kα). Magnetic properties were measured using a vibrating sample magnetometer (VSM) at room temperature with a maximum applied field of 2 T. To obtain the temperature profile of the surface roughness, magnetic, and structural properties, thin film samples were air quenched to room temperature after annealing to a particular temperature within the range between 150 and 500°C.