Performance of a corona ion source for measurement of sulfuric acid by chemical ionization mass spectrometry

The performance of an ion source based on corona discharge has been studied. This source is used for the detection of gaseous sulfuric acid by chemical ionization mass spectrometry (CIMS) through the reaction of NO−3 ions with H2SO4. The ion source is operated under atmospheric pressure and its design is similar to the one of a radioactive (americium-241) ion source which has been used previously. The results show that the detection limit for the corona ion source is sufficiently good for most applications. For an integration time of 1 min it is ~6×104 molecule cm−3 of H2SO4. In addition, only a small cross-sensitivity to SO2 has been observed for concentrations as high as 1 ppmv in the sample gas. This low sensitivity to SO2 is achieved even without the addition of an OH scavenger. When comparing the new corona ion source with the americium ion source for the same provided H2SO4 concentration, both ion sources yield almost identical values. These features make the corona ion source investigated here favorable over the more commonly used radioactive ion sources for most applications where H2SO4 is measured by CIMS

Tools of Measurement for European Travelers – George Staunton’s An Authentic Account of an Embassy from the King of Great Britain to the Emperor of China (1797)

Today the Macartney mission and the account of it written down by George Staunton is being widely regarded as a milestone in the way how the west viewed China and its people. However, such a travel report did not necessarily give an ‘objective’ account on another country or culture. Therefore it is important to consider the mindset of the travelers. The Europeans had specific knowledge about China already prior to their departure and especially what they believed to know about the attitude of the Chinese towards science and technology was important. The travelers of the embassy othered the Chinese, based on assumptions made by Enlightenment thinkers and philosophers who wrote extensively about China. This chapter will analyze the way that the Europeans othered the Chinese in that context. Two hundred years after the embassy, in 1992, the British Association for Chinese Studies presented several papers on the Macartney embassy. While the travel account has been object of studies in many different fields and papers from many disciplines were presented, none of them focuses on the underlying agenda of the Europeans; that is their approach towards science and technology. The embassy is correctly considered a collision of fundamentally different civilizations and ideologies. However, the question of in how far the approach towards science, technology and the relation that they share towards progress is responsible for this collision remains unanswered. In fact many science and technology studies focused on the advances of the sciences within a culture; the attitude of a culture towards science in general was on the other hand rarely an object of study

Modeling of packed bed membrane reactors: impact of oxygen distribution on conversion and selectivity in partial oxidation systems

In this thesis the focus is on the effect of the oxygen distribution on the performance of the PBMR in terms of conversion and selectivities. A detailed description of the oxygen transport through the membrane is not considered in this work. Here, the membrane is considered as an ideal distributor with a fixed membrane flow, independent from the reaction conditions inside the packed bed. This assumption enables an independent discussion of the influence of the oxygen distribution on the performance of the PBMR

Numerical simulations of mixing conditions and aerosol dynamics in the CERN CLOUD chamber

To study the effect of galactic cosmic rays on aerosols and clouds, the Cosmics Leaving OUtdoor Droplets (CLOUD) project was established. Experiments are carried out at a 26.1 m3 tank at CERN (Switzerland). In the experiments, the effect of ionizing radiation on H2SO4 particle formation and growth is investigated. To evaluate the experimental configuration, the experiment was simulated using a coupled multidimensional computational fluid dynamics (CFD) – particle model. In the model the coupled fields of gas/vapor species, temperature, flow velocity and particle properties were computed to investigate mixing state and mixing times of the CLOUD tank's contents. Simulation results show that a 1-fan configuration, as used in first experiments, may not be sufficient to ensure a homogeneously mixed chamber. To mix the tank properly, two fans and sufficiently high fan speeds are necessary. The 1/e response times for instantaneous changes of wall temperature and saturation ratio were found to be in the order of few minutes. Particle nucleation and growth was also simulated and particle number size distribution properties of the freshly nucleated particles (particle number, mean size, standard deviation of the assumed log-normal distribution) were found to be distributed over the tank's volume similar to the gas species

How the traditional office evolved into the digital workplace

The nature of workplaces is changing. Digital technology has constantly evolved and enabled workplaces to progress from being static in location to becoming independent of location. Digital technology enabled a digital workplace that can always be with the employee. The objective of this dissertation is to investigate the drivers and enablers behind the evolution of the workplace from a traditional office to a digital workplace. Through the use of expert interviews from important industries in Germany and secondary research the aim is to determine the key drivers behind the digitalization of workplaces as well as the technologies that enabled this workplace transformation. The industries are ranging from consulting, the medium-sized industry, telecommunication, digital marketing and management. The findings of the dissertation are that the drivers for businesses to digitalize their workplaces are often work culture related. This stems from the wish for more flexible working conditions to the covid-19 pandemic and an increase in complex work as well as others. The digitalization of workplaces is especially supported and enabled through key technologies like SaaS, Cloud services, Customer analytics systems among others. Finally, current findings from the literature as well as expert interviews, certify that companies will get the most productivity and efficiency from their employees if they grant them the freedom of choice with their work environment.A natureza dos locais de trabalho está a mudar. A tecnologia digital tem evoluído constantemente e permitiu que os locais de trabalho passassem de estáticos no local para independentes do local. A tecnologia digital possibilitou um local de trabalho digital que pode estar sempre com o empregado. O objectivo desta dissertação é investigar os condutores e capacitadores por detrás da evolução do local de trabalho, de um escritório tradicional para um local de trabalho digital. Através da utilização de entrevistas de peritos de indústrias importantes na Alemanha e de investigação secundária, o objectivo é determinar os principais motores por detrás da digitalização dos locais de trabalho, bem como as tecnologias que permitiram esta transformação do local de trabalho. As indústrias vão desde a consultoria, a indústria de média dimensão, as telecomunicações, o marketing digital e a gestão. As conclusões da dissertação são que os motores das empresas para digitalizar os seus locais de trabalho estão muitas vezes relacionados com a cultura de trabalho. Isto deriva do desejo de condições de trabalho mais flexíveis à pandemia covid-19 e de um aumento do trabalho complexo, bem como de outros. A digitalização dos locais de trabalho é especialmente apoiada e possibilitada através de tecnologias chave como SaaS, serviços Cloud, sistemas analíticos de clientes, entre outros. Finalmente, os resultados actuais da literatura, bem como as entrevistas de peritos, certificam que as empresas obterão a maior produtividade e eficiência dos seus empregados se lhes concederem a liberdade de escolha com o seu ambiente de trabalho

Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures

Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia are thought to be the dominant processes responsible for new particle formation (NPF) in the cold temperatures of the middle and upper troposphere. Ions are also thought to be important for particle nucleation in these regions. However, global models presently lack experimentally measured NPF rates under controlled laboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here with data obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets) chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. The conditions during nucleation cover a temperature range from 208 to 298 K, sulfuric acid concentrations between 5 × 10^5 and 1 × 10^9 cm^(−3), and ammonia mixing ratios from zero added ammonia, i.e., nominally pure binary, to a maximum of ~1400 parts per trillion by volume (pptv). We performed nucleation studies under pure neutral conditions with zero ions being present in the chamber and at ionization rates of up to 75 ion pairs cm^(−3) s^(−1) to study neutral and ion-induced nucleation. We found that the contribution from ion-induced nucleation is small at temperatures between 208 and 248 K when ammonia is present at several pptv or higher. However, the presence of charges significantly enhances the nucleation rates, especially at 248 K with zero added ammonia, and for higher temperatures independent of NH_3 levels. We compare these experimental data with calculated cluster formation rates from the Atmospheric Cluster Dynamics Code with cluster evaporation rates obtained from quantum chemistry

Übergang Schule-Fachhochschule – Konzept und erste Ergebnisse aus dem Projekt Rechenbrücke

Im Rahmen des Kooperationsprojekts „Rechenbrücke“ der Fachhochschule und der Universität Münster werden Studienanfänger eines ingenieurwissenschaftlichen Studiums in der Studieneingangsphase unterstützt schulmathematische Defizite auszugleichen. Im Folgenden werden Überlegungen zur Konzeption von Vorkursen und Tests im Zusammenhang mit diesem Projekt, das unter anderem einen modularisierten Vorkurs, diagnostische Tests und Online-Angebote enthält, vorgestellt und erste Ergebnisse präsentiert