Small Amount Of Incorporation Research Articles

Heterogeneous Ni- and Cd-Bearing Ferrihydrite Precipitation and Recrystallization on Quartz under Acidic pH Condition

Ferrihydrite, as one of the most common naturally occurring iron oxides, can sequester toxic metals through coprecipitation. In this study, using grazing-incidence small angle X-ray scattering (GISAXS), the heterogeneous precipitation of pure, Ni-, and Cd- bearing ferrihydrite on quartz were quantified in 0.1 mM Fe3+ solutions in the absence and presence of 1 mM Ni2+ or Cd2+ (pH = 3.8 ± 0.1). Under acidic condition, the limited hydrolysis of metal ions resulted in their small amounts of incorporation in ferrihydrite lattices (< 0.1%), several orders of magnitude lower than those reported at neutral and alkaline pH conditions. The presence of Ni2+ or Cd2+ did not significantly affect the surface charges of either ferrihydrite pre-nucleation clusters (PNCs) or quartz surfaces. Therefore, with similar electrostatic interactions between PNCs and quartz, similar initial heterogeneous precipitation rates of pure, Ni-, and Cd- bearing ferrihydrite on quartz were observed. Later on, continuous heterogeneous nucle...

Thermophysical Properties of Alumina Particle Reinforced Glass Matrix Composites

Alumina particles incorporated glass matrix composites, which showed good prospect to be used as coating materials for high‐temperature corrosion protection on intermetallics or titanium alloys, were prepared via pressureless sintering. With increasing alumina content, the Young's modulus, fracture strength, Vickers hardness, indentation toughness, softening point, and thermal shock resistance of the composites increased monotonically. A similar increasing trend could be found for the thermal expansion coefficient of the composites, except for an abnormal drop at small amount of incorporation, which closely correlated with the Al3+ dissolution into the glass matrix.

Kinetics of arsenic doping in silicon by ultra-high-vacuum chemical vapor deposition

Segregation of arsenic and suppression of decomposition of source molecules during the growth of silicon by ultra-high-vacuum chemical vapor deposition is investigated. At the surface, the incidence and the desorption of arsenic balances with a small amount of incorporation. Almost all dopant atoms segregate on the surface during the growth and the rest are incorporated. Thus, the doping concentration is governed by the competition between the growth rate of Si crystal and the segregation speed of the dopant. The high doping concentration was obtained at high growth temperature, because the increment of the growth rate is larger than that of the segregation speed in accordance with the temperature. The dependence of doping concentration on AsH 3 pressure is explained by this model.

Incorporation of a naturally occurring fluorescent fatty acid into lipids of cultured mammalian cells.

A fluorescent fatty acid, cis-parinaric acid (cis-PnA), has been biosynthetically incorporated by cultured mammalian cells. The fatty acid probe is predominantly incorporated into phospholipids, with a small amount of incorporation into the neutral lipid fraction. Both phosphatidylethanolamine and phosphatidylcholine are labeled with the fluorescent probe. The temperature dependence of the fluorescence intensity of cis-PnA, either biosynthetically incorporated or added as the free fatty acid, suggests thermally induced structural reorganizations in phospholipids isolated from cultured cells enriched in palmitic acid. Results are essentially identical with both forms of the probe.

The synthesis of nucleic acids and proteins in the nuclei of Tradescantia root tips

An autoradiographic and isotopic study was made of the synthesis of DNA, RNA and some nuclear proteins in root tip nuclei of Tradescantia. 1. 1. During the growth of the nucleus in early interphase, there is no incorporation of tritium labelled thymidine into DNA. After a nucleus reaches a certain size, however, there is incorporation into DNA with little or no further increase in nuclear volume. 2. 2. The incorporation of orotic acid- 14C into both RNA and DNA of the same nucleus was studied. A plot of incorporation into RNA against incorporation into DNA for a short exposure to isotope (6 hours) shows an inverse relationship. This was interpreted to mean that the two nucleic acids are not synthesized together. 3. 3. A similar plot for a long term exposure (12 hours) is interpreted to mean that the peak of RNA synthesis occurs prior to DNA synthesis. However, a small amount of incorporation was found to take place after DNA synthesis. 4. 4. The plot of incorporation of orotic acid- 14C into RNA of those cells with no incorporation into DNA in the short term experiment indicates that RNA is being synthesized when an increase in volume of the nucleus occurs. Since the thymidine experiments showed no incorporation into DNA during increase in nuclear volume, this is an additional, independent indication of the validity of the concept that most of the RNA synthesis occurs before DNA synthesis in this material. 5. 5. Under the conditions of this experiment, it takes a cell at least eight hours to go from the end of DNA synthesis to prophase and prophase to telophase takes approximately two hours. 6. 6. The incorporation of lysine- 14C into nuclear proteins which are not removed by the Feulgen hydrolysis was studied. Since after a six hour exposure to isotope, nuclei of all volumes and stages of division appeared to be labelled, both in chromatin and nucleolus when present, it was concluded that protein synthesis probably occurs in all stages of the cell cycle.