The 70 ev positive and negative ion mass spectra of ring-substituted nitrobenzenes were studied. The influence of the substituent group on the fragmentation modes of the molecular ions is discussed. The effect of pressure in the formation of negative ions was also studied. As expected, the ratio of fragment ions to negative molecular ions decreased with increasing pressure in ion source.

des monocristaux de fluoraptite calcique dopes avec des ions mn substitues aux ions ca ont ete prepares en utilisant une methode de synthese qui permet de l'obtenir avec une faible concentration en defauts le long de l'axe senaire helicoidal. dans ces conditions les spectres d'excitation et de rpe montrent que les ions mn se placent uniquement dans ie site ca(l).

introduction: heavy ions are nucleus of elements of iron, argon, carbon and neon that all carry positive electrical charges. for these particles to be useful in radiotherapy they need to accelerated to high energy by more than thousand mega volts. also the cosmic environment is considered to be a complicated mixture of highly energetic photons and heavy ions such as iron. therefore, the health ...

we studied the effect of different concentrations of alpha-tocopherol on in vitro cupric ions induced oxidation of low density lipoproteins (ldl). human native ldl (50 µg protein/ml) oxidation was induced by 10 µmol/l of cuso4. conjugated dienes were measured spectrophotometrically for up to 440 minutes. the length of the lag phase (tlag), maximum velocity of the reaction (vmax) and the maximum...

background: lead (pb) is a heavy metal that is widely utilized in industries. it contaminates soil and groundwater. its non-biodegradability, severe toxicity, carcinogenicity, ability to accumulate in nature and contaminate groundwater and surface water make this toxic heavy metal extremely dangerous to living beings and the environment. therefore, technical and economic methods of removing pb ...

in this research, the groundwater quality of hoz–e–soltan lake and its catchment was studied for drinking, domestic and irrigation uses according to different parameters. this lake with 195 km2 catchment area is located 85 km of southwest of tehran–qom highway. in order to investigate groundwater quality characteristics in the study area, 34 data from water of well belong to 2008 selected to pr...

crown ethers 12-crown-4 (12c4), benzo-15-crown-5 (b15c5), 18-crown-6 (18c6), nitrobenzo-18-crown-6 (nb18c6) dibenzo-18-crown-6 (db18c6) and dicyclohexyl-18-crown-6 (dc18c6), dissolved in dichloromethane, are able to form oxonium-ion complexes in contact with aqueous sulfuric and hydrochloric acid solutions. this ability allows the transfer of cr(vi) oxanions from the acid media, through an orga...

background: the fatal effect of ionizing radiation on cells depends on linear energy transfer (let) level. the distribution of ionizing radiation is sparse and homogeneous for low let radiations such as x or γ, but it is dense and concentrated for high let radiation such as heavy-ions radiation. material and methods: chinese hamster ovary cells (cho-k1) were exposed to 4 gy fe-ion 2000 kev/m. ...

BACKGROUND: Some of metal ions as environmental pollutants show estrogenic activity. This xenostrogenic compounds can be caused carcinogenicity in organs. The mechanism of carcinogenicity of metal ions is not clarified. OBJECTIVES: In this study, we investigated the Transcriptional effects of variety of metal ions on the bovine oxytocin and the thymidine kinase-ERE promoter by estrogen receptor...