Santokh S. Badesha

Nanotechnology Environmental, Health, and Safety Issues

The environmental, health, and safety (EHS) of nanomaterials has been defined as “the collection of fields associated with the terms ‘environmental health, human health, animal health, and safety’ when used in the context of risk assessment and risk management” ([1], p. 2). In this chapter, the term “nano-EHS” is used for convenience to refer specifically to environmental, health, and safety research and related activities as they apply to nanoscale science, technology, and engineering. This chapter outlines the major advances in nano EHS over the last 10 years and the major challenges, developments, and achievements that we can expect over the next 10 years without providing comprehensive coverage or a review of all the important issues in this field.

Reversible chemical modification of the electrical behavior of a-Se

Abstract a -Se films prepared from either high purity (99.999%) source material which has undergone hydrazine reduction or from high purity Se powder surface treated with hydrazine exhibit enhanced electron and diminished hole mobility lifetime (μτ) products relative to source material. The effect of this chemical treatment is stable enough to survive repeated distillation of the selenium. A history of hydrazine reduction or surface treatment, however, has no effect on hole or electron drift mobility. The effect of hydrazine exposure can be completely reversed by oxidation of selenium oxide with nitric acid followed by reprecipitation of selenium with SO 2 . The effect of hydrazine on the photoelectronic behavior of a -Se is restricted to changes in the near midgap density of states and may involve, at least in part, chemical modification of pre-existing native defects.

Practical surfaces: beyond the wheel

In this paper, we explore the challenges of designing practical surfaces for the 21st century. By building upon examples from different industries, we derive a number of useful tenets intended to guide those who face these challenges through the maze of technical and economic issues that they may confront. Given that future opportunities abound for surfaces having new and better properties, we describe some emerging materials systems that are likely to yield these improvements.

Chemical process to normalize the electrical properties of a-Se

The influence of specific chemical dopants on the electrophotographic behavior of selenium and its alloys has been established in prior work. This communication describes a chemical procedure that has been found effective in removing electronically active impurities from amorphous selenium. The methodology involves converting contaminated selenium into a chemical intermediate that is separated by selective alcoholic dissolution and then reduced to high-purity selenium. The electrical characteristics of the amorphous films obtained by vacuum evaporation of the latter are determined directly from analysis of xerographic potentials.

Electrochemical reduction of chalcogenide esters in non-aqueous medium, 2-ethoxy ethanol

Abstract Electrochemical reduction of bis(arsenic triglycollate) (CH 2 O) 2 AsO(CH 2 ) 2 OAs(OCH 2 ) 2 dimethyl sulfite (CH 3 O) 2 SO, diethylselenite, (C 2 H 5 O) 2 SeO, and ethylene tellurite, (OCH 2 CH 2 O) 2 Te was studied in non-aqueous, 2-ethoxy ethanol (cellosolve) using single-sweep voltammetry and cyclic voltammetry. It is shown that arsenic, sulfur, selenium and tellurium deposit at the cathode at bias potentials of −0.70, −0.64, −0.51 and −0.22 V vs Ag/AgCl, aq. KCl respectively.

Tellurium-125 Mössbauer spectroscopy and X-ray powder diffraction investigation of selenium-tellurium alloys prepared by novel methods

Abstract Selenium-tellurium alloys prepared by a novel route involving the co-reduction of selenium- and tellurium-esters with hydrazine are shown by X-ray powder diffraction to be more crystalline than analogous alloys prepared by conventional annealing processes. The 125 Te Mossbauer spectra are consistent with increasing interchain bonding as the tellurium content of the alloys is increased. The electronic environments of tellurium in the alloys prepared by precipitation are similar to those in alloys prepared by annealing processes.