Simple relationships between the ionization energies of one-, two- and three-electron ions of consecutive elements

The ionization energy of one-electron ions can be calculated from a well-known equation that is based on quantum mechanics and on the Bohr model, but no theoretically justified equation is available for the calculation of the ionization energies of multi-electron ions. I report here simple empirical relationships between the ionization energies of one-, two- and three-electron ions of elements whose atomic numbers are Z, Z + 1 and Z + 2. On the basis of these relationships, an equation was constructed for the calculation of the ionization energies of two- and three-electron ions (IE(2el)(Z) and IE(3el)(Z), respectively) as a function of Z only: [equation: see text] where N = the number of electrons, i.e. 2 or 3. For N = 3, this equation is only valid when Z > N, being inaccurate for the neutral Li atom. Graphs of the difference between calculated and experimental values of the ionization energies as a function of Z reveal inaccurate experimental results that are impossible to detect by inspection of the ionization energy itself. On the basis of the present results, more accurate values can be predicted for these ionization energies. A striking example is the inaccuracy of the traditional handbook value of IE(3el)(Fe).     

A simple formula to calculate the ionization energies of two-, three-, and four-electron atomic ions

We have previously proposed a simple equation that is able to reproduce literature values (Moore 1970) for the ionization energies of one-electron (Lang and Smith 1981) and two-electron (Sabir Ali et al. 1984) atomic ions with very good agreement. However, our proposed equation has no firm theoretical basis, only that we consider our potential energy approach a logical alternative to the usual kinetic relativistic/quantum mechanical methodology. The results calculated from the equation give excellent agreement with literature values and differ by less than 1 eV and less than 0.02% in all cases from hydrogen up to atomic number 20. This paper provides an updated version of the two-electron equation adapted to calculate the ionization energies of three and four electron ions. Our equation also gives fairly good estimates of first electron affinities. Comparisons are made with another published equation, sources of data are described, and the calculated results are discussed.     

Evaluation of the adsorption potential of titanium dioxide nanoparticles for arsenic removal

The adsorption potential of titanium dioxide (TiO2) nanoparticles for removing arsenic from drinking water was evaluated. Pure and iron-doped TiO2 particles are synthesized via sol-gel method. The synthesized TiO2 nanoparticles were then immobilized on ordinary sand for adsorption studies. Adsorption isotherms were conducted on the synthesized nanoparticles as well as the sand coated with TiO2 nanoparticles under varying conditions of air and light, namely, the air-sunlight (A-SL), air-light (AL), air-dark (AD) and nitrogen-dark (ND). X-Ray diffraction (XRD) analysis showed that the pure and the iron-doped TiO2 nanoparticles were in 100% anatase crystalline phase with crystal sizes of 108 and 65 nm, respectively.Adsorption of arsenic on the three adsorbents was non-linear that could be described by the Freundlich and Langmuir adsorption models. Iron doping enhanced the adsorption capacity of TiO2 nanoparticle by arresting its grain growth and making it visible light responsive resulting in a higher affinity for arsenic. Similarly, the arsenic removal by adsorption on the sand coated with TiO2 nanoparticles was the highest among the three types of sand used. In all cases, As(V) adsorbed more compared with As(III). Solution pH appeared to be the most important factor in controlling the amount of arsenic adsorbed.     

A simple,rapid, and highly informative PCR-based procedure for prenatal diagnosis and carrier screening of phenylketonuria

The polymorphic information content (PIC) and the degree of heterozygosity of several polymorphic systems within the phenylalanine hydroxylase (PAH) gene were determined in 85 European Caucasian and 19 Chinese phenylketonuria (PKU) kindreds. The first system examined, a short tandem repeat (STR), had a PIC of 80 and 73 per cent in these Caucasian and Chinese samples, respectively. The degree of heterozygosity actually observed for this system was 81 and 64 per cent in the Caucasian and Chinese PKU families, respectively. Through the addition of a second polymorphism based on a variable number of tandem repeats (VNTR), the PIC was increased to 90 per cent in Caucasians, but only to 75 per cent in Chinese. The degree of heterozygosity observed for this combination was 94 per cent in European PKU families and 67 per cent in Chinese PKU families. The further addition of an Xmnl RFLP increased both the PIC and the level of heterozygosity in Caucasians to 95 per cent, but did not change either of these measures in Chinese. The combined use of these three polymorphisms significantly increases the informativity of prenatal diagnostic and carrier screening procedures in both Caucasian and Chinese PKU kindreds. Furthermore, since each of these polymorphisms can be studied by PCR-based methods, these new tests can be performed more quickly and easily than previous Southern-based procedures.     

浅谈生态类--气田水输送管道工程竣工环保验收调查

就生态影响类建设项目中气田水输送管道工程对环境影响的特征进行了分析,对该类竣工环保验收调查的内容、重点进行了探究。