Do people react more strongly to aircraft noise today than in the past?

Some researchers have suggested that recent studies of aircraft noise annoyance indicate that people react more strongly to a given noise exposure level today than in the past, but is there good statistical evidence to support this hypothesis? This paper reviews the correspondence between aircraft noise exposure and annoyance responses reported in aircraft noise study analyses undertaken over a period of decades. Simple linear regression models and textbook statistical analyses are used to test the data. There are some indications of an upward trend in annoyance versus noise exposure over the last 25 years, but basic tests show that the statistical evidence for an upward trend is weak, and may simply be due to sampling and/or methodological differences between the studies. The survey collection method may play a role. In some cases, study participation rate effects may exaggerate community responses.     

火焰原子吸收光谱法测定锌锭中铅铁镉铜

研究了有机试剂丙酮对火焰原子吸收光谱法测定锌锭中各元素的增敏作用,建立了混合酸直接溶样,丙酮为增敏剂,测定各种牌号锌锭中铅、铁、镉、铜的方法。试验结果表明,该方法简单、快速、准确、可靠。     

Mechanism based structure-activity relationships for skin sensitisation--the carbonyl group domain

The biological activity of skin-sensitising chemicals is related to their ability to react either directly or after metabolic activity with appropriate skin proteins. For direct-acting electrophilic compounds, this ability can be modelled by the Relative Alkylation Index (RAI) by a combination of electrophilicity and hydrophobicity parameters. Several SARs based on this approach are reported. In this present work, electrophilicity parameters based on Taft substituent constants are used together with Leo and Hansch log P fragment values to calculate RAI values for hard electrophiles having a reactive carbonyl group. These are then applied to analysis of sensitisation data obtained in the murine Local Lymph Node Assay (LLNA) for two series of diketones as well as a homologous series of alpha, beta-unsaturated aldehydes. The sensitisation potentials of these reactive electrophiles show good correlations with the RAI. These findings re-affirm the view that physicochemical parameters are the key to eliciting the relationship between chemical structure and a toxic endpoint. They provide further evidence of the value of SAR studies in identifying mechanisms of sensitisation and aiding risk assessments without the need for extensive animal testing.     

VUV sensitisation of Eu emission by Tb in Ba3Tb(PO4)3-Eu

The luminescence properties of Ba₃Tb_0.9Eu_0.1(PO₄)₃ and Ba₃Gd_0.9Eu_0.1(PO₄)₃ phosphors were studied for excitation over the 120-300 nm wavelength range. It is found that Tb³⁺, which exhibits a strong vacuum-ultraviolet (VUV) absorption band, provides sensitisation of Eu³⁺ emission in this host. This effect can be used to develop phosphors with enhanced conversion efficiency of the VUV radiation into visible light.     

Sensitisation of erbium emission by silicon nanocrystals-doped SnO2

SnO₂ thin films undoped and doped with antimony (Sb), erbium (Er) and Si nanocrystals (Si-nc) have been grown on silicon (Si) substrate using sol-gel method. Room-temperature photoluminescence (PL) measurement of undoped SnO₂, under excitation at 280 nm, shows only one broad emission at 395 nm, which is related to oxygen vacancies. The PL of Er³⁺ ions was found to be enhanced after doping SnO₂ with Sb and Si-nc. The excitation process of Er is studied and discussed. The calculation of cross-section suggests a sensitisation of Er PL by Si-nc.