Photoactive Titanium Dioxide Films with Embedded Gold Nanoparticles for Quantitative Determination of Mercury Traces in Humic Matter-Containing Freshwaters.

Mercury detection in humic matter-containing natural waters is often associated with environmental harmful substances for sample preparation. Herein we report an approach based on photoactive titanium dioxide films with embedded gold nanoparticles (AuNP@TiO2 dipstick) for chemical-free sample preparation and mercury preconcentration. For this purpose, AuNPs are immobilized onto a silicon wafer and further covered with a thin photoactive titanium dioxide layer. The AuNPs allow the preconcentration of Hg traces via amalgamation, while TiO2 acts as a protective layer and, at the same time, as a photocatalyst for UV-C radiation-based sample pretreatment. Humic matter, often present in natural waters, forms stabile complexes with Hg and so hinders its preconcentration prior to detection, causing a minor recovery. This problem is solved here by irradiation during Hg preconcentration onto the photoactive dipstick, resulting in a limit of detection as low as 0.137 ng L-1 using atomic fluorescence spectrometry (AFS). A 5 min preconcentration step is sufficient to obtain successful recovery of Hg traces from waters with up to 10 mg L-1 DOC. The feasibility of the approach was demonstrated by the determination of Hg traces in Danube river water. The results show no significant differences in comparison with standard cold vapor-atomic fluorescence spectrometry (CV-AFS) measurements of the same sample. Hence, this new AuNP@TiO2 dipstick provides a single-step sample preparation and preconcentration approach that combines sustainability with high analytical sensitivity and accuracy.

Digitalization within the MME study program - teaching and assessment of communicative and interprofessional skills in the Heidelberg module via video conference together with a virtual OSCE course.

Background: Due to the corona pandemic, we conducted the Heidelberg module of the Master of Medical Education (MME) study program, which focuses on teaching and assessment of communicative and interpofessional skills, digitally for the first time. Method: We outsourced the teaching to a pre-module phase in the weeks upfront. During the module week, the lecturers picked up again and deepened the topics and the participants created, revised and simulated a virtual OSCE course. Results/Conclusion: Evaluation and reflection of the module showed that the digital implementation including an OSCE examination can be an appropriate alternative to a classroom-based training. However, important elements of the MME program that provide networking possibilities and personal exchange can only be replicated in the digital environment to a limited extent. In the future, sensibly applied digital components can be used to enrich the study program.

Medical assessment in the age of digitalisation.

BACKGROUND: Digital assessment is becoming more and more popular within medical education. To analyse the dimensions of this digital trend, we investigated how exam questions (items) are created and designed for use in digital medical assessments in Germany. Thus, we want to explore whether different types of media are used for item creation and if a digital trend in medical assessment can be observed. METHODS: In a cross-sectional descriptive study, we examined data of 30 German medical faculties stored within a common assessment platform. More precise, 23,008 exams which contained 847,137 items were analysed concerning the exam type (paper-, computer- or tablet-based) and their respective media content (picture, video and/or audio). Out of these, 5252 electronic exams with 12,214 questions were evaluated. The media types per individual question were quantified. RESULTS: The amount of computer- and tablet-based exams were rapidly increasing from 2012 until 2018. Computer- and tablet-based written exams showed with 45 and 66% a higher percentage of exams containing media in comparison to paper-based exams (33%). Analysis on the level of individual questions showed that 90.8% of questions had one single picture. The remaining questions contained either more than one picture (2.9%), video (2.7%), audio (0.2%) or 3.3% of questions had picture as well as video added. The main question types used for items with one picture are TypeA (54%) and Long_Menu (31%). In contrast, questions with video content contain only 11% TypeA questions, whereas Long_Menu is represented by 66%. Nearly all questions containing both picture and video are Long_Menu questions. CONCLUSIONS: It can be stated that digital assessment formats are indeed on the raise. Moreover, our data indicates that electronic assessments formats have easier options to embed media items and thus show a higher frequency of media addition. We even identified the usage of different media types in the same question and this innovative item design could be a useful feature for the creation of medical assessments. Moreover, the choice of media type seems to depend on the respective question type.

Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water.

Trace-level detection of mercury in waters is connected with several complications including complex multistep analysis routines, applying additional, harmful reagents increasing the risk of contamination, and the need for expensive analysis equipment. Here, we present a straightforward reagent-free approach for mercury trace determination using a novel thin film sampling stick for passive sampling based on gold nanoparticles. The nanoparticles supported on a silicon wafer and further covered with a thin layer of mesoporous silica. The mesoporous silica layer is acting as a protection layer preventing gold desorption upon exposure to water. The gold nanoparticles are created by thermal treatment of a homogenous gold layer on silicon wafer prepared by vacuum evaporation. This gold-covered substrate is subsequently covered by a layer of mesoporous silica through dip-coating. Dissolved mercury ions are extracted from a water sample, e.g., river water, by incorporation into the gold matrix in a diffusion-controlled manner. Thus, the amount of mercury accumulated during sampling depends on the mercury concentration of the water sample, the accumulation time, as well as the size of the substrate. Therefore, the experimental conditions can be chosen to fit any given mercury concentration level without loss of sensitivity. Determination of the mercury amount collected on the stick is performed after thermal desorption of mercury in the gas phase using atomic fluorescence spectrometry. Furthermore, the substrates can be re-used several tens of times without any loss of performance, and the batch-to-batch variations are minimal. Therefore, the nanogold-mesoporous silica sampling substrates allow for highly sensitive, simple, and reagent-free determination of mercury trace concentrations in waters, which should also be applicable for on-site analysis. Successful validation of the method was shown by measurement of mercury concentration in the certified reference material ORMS-5, a river water.