Skip to main content
Login | Suomeksi | På svenska | In English

Browsing by Subject "5"

Sort by: Order: Results:

  • Computational studies of dibenzotetraaza[14]annulene Ni(II) and Zn(II) complexes 
    Pruikkonen, Sanni (2021)
    Stacking of antiaromatic molecules leads to enhanced stability and higher conductivity due to reversed antiarotmaticity. It has been shown that cyclophenes consisting of antiaromatic Ni(II) norrcorrole subunits have a vertical current-density flux between the two metal ions. The Ni(II) meso- substituted dibenzotetraaza[14]annulene complex fulfills the Hückel rule for being antiaromatic. Upon increasing the temperature above 13 K, the effective magnetic moment of solid state Ni(II) meso-substituted dibenzotetraaza[14]annulene changes from being diamagnet to paramagnetic. A suggested explanation for this is that there might be weak interaction between the Ni atoms. In this study the possibility of the existence of vertical current-density flux between the two metal ions in the Ni(II) meso-substituted dibenzotetraaza[14]annulene is investigated. In addition, the effect of the Ni and N atoms in Ni(II) 1,5,9,13-tetraaza[16]annulene was studied by replacing Ni and Zn and N with O. Electronic motion in molecules that are under the influence of a magnetic field is investigated computationally, since at present there is no routine experimental method for doing that. TURBOMOLE, the Gauge-including Magnetically Induced Currents method and Paraview were employed in this study for structure optimization of the molecules, calculation of current-density flux and current strength in the molecules and visualisation of the current-density pathways respectively. The results of this study does not show any current transport between the subunits in the Ni(II) meso-substituted dibenzotetraaza[14]annulene complex. Both the Ni(II) 1,5,9,13-tetraaza[16]annulene and the Zn(II) 1,5,9,13-tetraaza[16]annulene are aromatic but they were not stacked due to their distorted structure. The (2Z,7Z,10Z,14Z)-1,9-dioxa-5,13-diazacyclohexadeca-2,7,10,14-tetraene-5,13-diide complexes with either Zn(II) or Ni(II) were both non-aromatic as well as the Ni(II) (2Z,7Z,10Z,14Z)-1,9-dioxa-5,13-diazacyclohexadeca-2,7,10,14-tetraene-5,13-diide dimer.
  • Covid-19 -pandemian hillitsemiseksi tehtyjen rajoitusten vaikutus Helsingin ilmanlaatuun tammikuusta syyskuuhun 2020 
    Huhtala, Jenni (2022)
    The aim of this thesis is to understand how restrictions and recommendations to limit the spread of Covid-19 pandemic affected air quality in Helsinki from January to September 2020 and examine the health benefits coming from the decreased pollutant levels. During that time many restrictions to people’s movements took place. This caused a decrease in traffic rates which in turn affected air quality. The air pollutants included in this study are nitrogen oxide (NOx), tropospheric ozone (O3) and particulate matter (PM2.5 and PM10). The data was uploaded from SMEAR III -station in Kumpula neighborhood and the results were obtained by comparing concentrations from 2020 to those of 2018-2019. The data were divided into three periods, which were studied separately. The first period was the time before the lockdown (1.1.-17.3.), 2nd period was during the lockdown (18.3.-15.6.), and the 3rd period was after the lockdown (16.6.-30.9.). In addition, the health effects caused by the changes in pollutant concentration were studied with a calculator for financial benefits of emission reductions made by Finnish Environment Institute. The change in NOx concentrations during 2020 compared to 2018-2019 were -36.4 % in 1st period, -26.5 % in 2nd period and +34.1 % in 3rd period. The changes for O3 were +4.8 % (1st period), -8.6 % (2nd period) and -11.6 % (3rd period). PM2.5 concentrations changed -39.4 % (2nd period) and 0.0 % (3rd period) and PM10 concentrations -46.9 % (2nd period) and -14.7 % (3rd period) during 2020 compared to 2018-2019. Decrease of NOx in 1st period caused 2 600 t€/y savings in costs of air pollution related health effects. The changes in PM2.5 and NOx generated savings of 38 000 t€/y during 2nd period and -2 400 t€/y during 3rd period. Even though the pollutant concentrations decreased in most periods, the decrease can’t be explained only by changes in traffic rates and human activities. Other factors contribute air pollutant levels as well, including atypical weather during 2020. The study could be continued by separating the effects of weather, traffic and other contributing factors in changes in air pollutant concentrations.
  • Covid-19 -pandemian hillitsemiseksi tehtyjen rajoitusten vaikutus Helsingin ilmanlaatuun tammikuusta syyskuuhun 2020 
    Huhtala, Jenni (2022)
    The aim of this thesis is to understand how restrictions and recommendations to limit the spread of Covid-19 pandemic affected air quality in Helsinki from January to September 2020 and examine the health benefits coming from the decreased pollutant levels. During that time many restrictions to people’s movements took place. This caused a decrease in traffic rates which in turn affected air quality. The air pollutants included in this study are nitrogen oxide (NOx), tropospheric ozone (O3) and particulate matter (PM2.5 and PM10). The data was uploaded from SMEAR III -station in Kumpula neighborhood and the results were obtained by comparing concentrations from 2020 to those of 2018-2019. The data were divided into three periods, which were studied separately. The first period was the time before the lockdown (1.1.-17.3.), 2nd period was during the lockdown (18.3.-15.6.), and the 3rd period was after the lockdown (16.6.-30.9.). In addition, the health effects caused by the changes in pollutant concentration were studied with a calculator for financial benefits of emission reductions made by Finnish Environment Institute. The change in NOx concentrations during 2020 compared to 2018-2019 were -36.4 % in 1st period, -26.5 % in 2nd period and +34.1 % in 3rd period. The changes for O3 were +4.8 % (1st period), -8.6 % (2nd period) and -11.6 % (3rd period). PM2.5 concentrations changed -39.4 % (2nd period) and 0.0 % (3rd period) and PM10 concentrations -46.9 % (2nd period) and -14.7 % (3rd period) during 2020 compared to 2018-2019. Decrease of NOx in 1st period caused 2 600 t€/y savings in costs of air pollution related health effects. The changes in PM2.5 and NOx generated savings of 38 000 t€/y during 2nd period and -2 400 t€/y during 3rd period. Even though the pollutant concentrations decreased in most periods, the decrease can’t be explained only by changes in traffic rates and human activities. Other factors contribute air pollutant levels as well, including atypical weather during 2020. The study could be continued by separating the effects of weather, traffic and other contributing factors in changes in air pollutant concentrations.

Yhteystiedot

HELSINGIN YLIOPISTO