O 4 , were prepared by high-temperature methods (1025-1050 °C; ∼80-150 h) from La 2 S 3 , Ti, S, and either La 2 O 3 or TiO 2 as oxygen sources. LaCl 3 (∼10-30 wt %) was added as a flux. The compounds were characterized by single-crystal X-ray diffraction, neutron activation analysis, and EDX analysis. All three compounds contain common ∞ 2 [(Ti 4 S 2 O 4 )(Ti-S 6 ) 4/2 ] (12+δ)oxysulfide layers and disordered/variable composition titanium sulfide layers that alternately stack along the c-axis of the unit cell. The titanium sulfide layers contain extensive La/Ti solid solution formation and are characterized by 5-fold disorders at the M(2) octahedral sites and 2-fold disorders at the M(3) sites. These compounds are members of a series of compounds with the general formula La 8+x Ti 8+y S 24 O 4 , where (x + y) e 2 and the oxidation states of Ti can vary from +3 to +4. Crystal data (153 K) of La 8.75 Ti 9.25 S 24 O 4 : tetragonal space group P4/mmm, a ) 10.4205(8) Å, c ) 8.3848(6) Å, V ) 910.5(1) Å 3 , Z ) 1, R(F) ) 3.88% and wR(F 2 ) ) 7.22%. For La 8.50 Ti 9.50 S 24 O 4 , tetragonal space group P4/mmm, a ) 10.4101(3) Å, c ) 8.396(1) Å, V ) 909.9(1) Å 3 , Z ) 1, R(F) ) 3.54% and wR(F 2 ) ) 8.16%. For La 8.10 Ti 8.05 S 24 O 4 , tetragonal space group P4/mmm, a ) 10.4212(3) Å, c ) 8.233(2) Å, V ) 894.1(2) Å 3 , Z ) 1, R(F) ) 4.25% and wR(F 2 ) ) 11.12%.
Abstract. NUCLEONICA is a new nuclear science web portal from the European Commission's Joint Research Centre. The portal provides a customisable, integrated environment and collaboration platform for the nuclear sciences using the latest internet "Web 2.0" dynamic technology. NUCLEONICA is aimed at professionals, academics and students working with radionuclides in fields as diverse as the life sciences (e.g., biology, medicine, agriculture), the earth sciences (geology, meteorology, environmental science) and the more traditional disciplines such as nuclear power, health physics and radiation protection, nuclear and radio-chemistry, and astrophysics. It is also used as a knowledge management tool to preserve nuclear knowledge built up over many decades by creating modern webbased versions of so-called legacy computer codes.
A contemporary PM2.5 (particulate matter smaller than 2.5 microns aerodynamic diameter) aerosol material from an urban site has been collected for the production of a new standard reference material that will be made available for the development of new PM2.5 air quality standards. Air particulate matter corresponding to the PM2.5 fraction was collected at an established Environmental Protection Agency monitoring site in Baltimore, Maryland. The air-sampling system that has been constructed for this collection separates fine particles with a cyclone separator and deposits them onto an array of Teflon membrane filters. The fine air particulate material is removed by ultrasonication or by mechanical means and collected for further preparation of standards. The composition of the collected PM2.5 aerosol, as well as the composition of the deposited PM2.5 aerosol, are determined by instrumental nuclear activation analysis and other techniques.
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