185 research outputs found
From building blocks to 2D networks
The aim of this work is to further the understanding of the important parameters in the formation process of 2D nanostructures and therewith pioneer for novel applications. Such 2D nanostructures can be composed of specially designed organic molecules, which are adsorbed on various surfaces. In order to study true 2D structures, monolayers were deposited. Their properties have been investigated by scanning tunneling microscopy (STM) under ultra-high vacuum (UHV) conditions as well as under ambient conditions. The latter is a highly dynamic environment, where several parameters come into play. Complementary surface analysis techniques such as low-energy electron diffraction (LEED), X-Ray photo-emission spectroscopy (XPS), and Raman spectroscopy were used when necessary to characterize these novel molecular networks. In order to conduct this type of experiments, high technical requirements have to be fulfilled, in particular for UHV experiments. Thus, the focus is on a drift-stable STM, which lays the foundation for high resolution STM topographs. Under ambient conditions, the liquid-solid STM can be easily upgraded by an injection add-on due to the highly flexible design. This special extension allows for adding extra solvent without impairing the high resolution of the STM data. Besides the device, also the quality of the tip is of pivotal importance. In order to meet the high requirements for STM tips, an in vacuo ion-sputtering and electron-beam annealing device was realized for the post-preparation of scanning probes within one device. This two-step cleaning process consists of an ion-sputtering step and subsequent thermal annealing of the probe. One study using this STM setup concerned the incorporation dynamics of coronene (COR) guest molecules into pre-existent pores of a rigid 2D supramolecular host networks of trimesic acid (TMA) as well as the larger analogous benzenetribenzoic acid (BTB) at the liquid-solid interface. By means of the injection add-on the additional solution containing the guest molecules was applied to the surface. At the same time the incorporation process was monitored by the STM. The incorporation dynamics into geometrically perfectly matched pores of trimesic acid as well as into the substantially larger pores of benzentribenzoic acid exhibit a clearly different behavior. For the BTB network instantaneous incorporation within the temporal resolution of the experiment was observed; for the TMA network, however, intermediate adsorption states of COR could be visualized before the final adsorption state was reached. A further issue addressed in this work is the generation of metal-organic frameworks (MOFs) under ultra-high vacuum conditions. A suitable building block therefore is an aromatic trithiol, i.e. 1,3,5-tris(4-mercaptophenyl)benzene (TMB). To understand the specific role of the substrate, the surface-mediated reaction has been studied on Cu(111) as well as on Ag(111). Room temperature deposition on both substrates results in densely packed trigonal structures. Yet, heating the Cu(111) with the TMB molecules to moderate temperature (150 °C) yields two different porous metal coordinated networks, depending on the initial surface coverage. For Ag(111) the first structural change occurs after annealing the sample at 300 °C. Here, several disordered structures with partially covalent disulfur bridges were identified. Proceeding further in the scope of increasing interaction strength between the building blocks, covalent organic frameworks (COFs) were studied under ultra-high vacuum conditions as well as under ambient conditions. For this purpose, a promising strategy is covalent coupling through radical addition reactions of appropriate monomers, i.e. halogenated aromatic molecules such as 1,3,5-tris(4-bromophenyl)benzene (TBPB) and 1,3,5-tris(4- iodophenyl)benzene (TIPB). Besides the correct choice of a catalytic surface, the activation energy for the scission of the carbon-halogen bonds is an essential parameter. In the case of ultra-high vacuum experiments, the influence of substrate temperature, material, and crystallographic orientation on the coupling reaction was studied. For reactive Cu(111) and Ag(110) surfaces room temperature deposition of TBPB already leads to a homolysis of the C-Br bond and subsequent formation of proto-polymers. Applying additional heat facilitates the transformation of proto-polymers into 2D covalent networks. In contrast, for Ag(111) just a variety of self-assembled and rather poorly ordered structures composed of intact molecules has emerged. The deposition onto substrates held at 80 K has never resulted in proto-polymers. For ambient conditions, the polymerization reaction of 1,3,5-tri(4-iodophenyl)benzene (TIPB) on Au(111) was studied by STM after drop-casting the monomer onto the substrate held either at room temperature or at 100 °C. For room temperature deposition only poorly ordered non-covalent arrangements were observed. In accordance with the established UHV protocol for halogenated coupling reaction, a covalent aryl-aryl coupling was accomplished for high temperature deposition. Interestingly, these covalent aggregates were not directly adsorbed on the Au(111) surface, but attached on top of a chemisorbed monolayer comprised of iodine and partially dehalogenated TIPB molecules. For a detailed analysis of the processes, the temperature dependent dehalogenation reaction was monitored by X-ray photoelectron spectroscopy under ultra-high vacuum conditions
Structuring User-Generated Content on Social Media with Multimodal Aspect-Based Sentiment Analysis
People post their opinions and experiences on social media, yielding rich
databases of end users' sentiments. This paper shows to what extent machine
learning can analyze and structure these databases. An automated data analysis
pipeline is deployed to provide insights into user-generated content for
researchers in other domains. First, the domain expert can select an image and
a term of interest. Then, the pipeline uses image retrieval to find all images
showing similar contents and applies aspect-based sentiment analysis to outline
users' opinions about the selected term. As part of an interdisciplinary
project between architecture and computer science researchers, an empirical
study of Hamburg's Elbphilharmonie was conveyed on 300 thousand posts from the
platform Flickr with the hashtag 'hamburg'. Image retrieval methods generated a
subset of slightly more than 1.5 thousand images displaying the
Elbphilharmonie. We found that these posts mainly convey a neutral or positive
sentiment towards it. With this pipeline, we suggest a new big data analysis
method that offers new insights into end-users opinions, e.g., for architecture
domain experts.Comment: 9 pages, 5 figures, short paper version to be published at 9th
IEEE/ACM International Conference on Big Data Computing, Applications and
Technologies (BDCAT2022
A combined ion-sputtering and electron-beam annealing device for the in vacuo postpreparation of scanning probes
A prospective cohort study in patients with type 2 diabetes mellitus for validation of biomarkers (PROVALID) âstudy design and baseline characteristics
Background/Aims: The prevalence of diabetes mellitus type 2 and kidney disease in these
patients varies widely between European countries. Methods: In addition to store biosamples
the âProspective cohort study in patients with type 2 diabetes mellitus for validation
of biomarkersâ collects information on history, physical status, laboratory measurements
and medication in 4000 patients with diabetes mellitus type 2, being taken care of at the
primary level of healthcare in 5 European countries (Austria, Hungary, Netherlands, Poland
and Scotland). Next to comparing the rate of loss of eGFR between the countries, a further
objective of the PROVALID study is to determine the 5-year cumulative incidence of renal and
cardiovascular outcomes. Results: The mean age of the population recruited is 62.9±10 years,
54.6% are male and the mean BMI is 30.9±5.4 kg/m2
. Metabolic control (median HBA1c 6.8
% (6.2;7.5)) is achieved via administration of metformin in 67.4% of the patients and insulin in 30.3%. Median systolic and diastolic blood pressure at recruitment is 135 (125;146) and 80
(72;85) mmHg, 65.4% of subjects received RAAS blocking agents. Mean eGFR is 80.7±29.2
ml/min/1.73m2
and median baseline albumin/creatinine ratio 8.3 mg (IQR: 3.8 and 25.1).
Conclusion: PROVALID will provide information on incidence and progression of renal and
cardiovascular disease and therapy in patients with type 2 diabetes mellitus in different
European countries. Thus, in contrast to many other cohort studies we will be able to associate
national clinical practise pattern with outcome in this highly vulnerable patient population
Genes involved in carnitine synthesis and carnitine uptake are up-regulated in the liver of sows during lactation
BACKGROUND:Convincing evidence exist that carnitine synthesis and uptake of carnitine into cells is regulated by peroxisome proliferator-activated receptor alpha (PPARA), a transcription factor which is physiologically activated during fasting or energy deprivation. Sows are typically in a negative energy balance during peak lactation. We investigated the hypothesis that genes involved in carnitine synthesis and uptake in the liver of sows are up-regulated during peak lactation. FINDINGS:Transcript levels of several PPARalpha target genes involved in fatty acid uptake (FABP4, SLC25A20), fatty acid oxidation (ACOX1, CYP4A24) and ketogenesis (HMGCS2, FGF21) were elevated in the liver of lactating compared to non-lactating sows (P < 0.05). In addition, transcript levels of genes involved in carnitine synthesis (ALDH9A1, TMLHE, BBOX1) and carnitine uptake (SLC22A5) in the liver were greater in lactating than in non-lactating sows (P < 0.05). Carnitine concentrations in liver and plasma were about 20% and 50%, respectively, lower in lactating than in non-lactating sows (P < 0.05), which is likely due to an increased loss of carnitine via the milk. CONCLUSIONS:The results of the present study show that PPARalpha is activated in the liver of sows during lactation which leads to an up-regulation of genes involved in carnitine synthesis and carnitine uptake. The PPARalpha mediated up-regulation of genes involved in carnitine synthesis and uptake in the liver of lactating sows may be regarded as an adaptive mechanism to maintain hepatic carnitine levels at a level sufficient to transport excessive amounts of fatty acids into the mitochondrion
Mesenchymal Stromal Cell-Based Therapy-An Alternative to Arthroplasty for the Treatment of Osteoarthritis? A State of the Art Review of Clinical Trials
Osteoarthritis (OA) is the most common degenerative joint disorder worldwide and to date no regenerative treatment has been established in clinical practice. This review evaluates the current literature on the clinical translation of mesenchymal stromal cell (MSC)-based therapy in OA management with a focus on safety, outcomes and procedural specifics. PubMed, Cochrane Library and clinicaltrials.gov were searched for clinical studies using MSCs for OA treatment. 290 articles were initially identified and 42 articles of interest, including a total of 1325 patients, remained for further examination. Most of the included studies used adipose tissue-derived MSCs or bone-marrow-derived MSCs to treat patients suffering from knee OA. MSC-based therapy for knee OA appears to be safe and presumably effective in selected parameters. Yet, a direct comparison between studies was difficult due to a pronounced variance regarding methodology, assessed outcomes and evidence levels. Intensive scientific engagement is needed to identify the most effective source and dosage of MSCs for OA treatment in the future. Consent on outcome measures has to be reached and eventually patient sub-populations need to be identified that will profit most from MSC-based treatment for OA
Match me, if you can â Zum Einfluss von persönlichkeitsbasierter Ăhnlichkeit zwischen Marke und Testimonial auf die wahrgenommene Passung und die Kaufwahrscheinlichkeit
Die Match-up-Hypothese besagt, dass eine fĂŒr ein Produkt werbende Person (Testimonial) dann besonders effektiv ist, wenn die Eigenschaften des Testimonials mit denen der Marke ĂŒbereinstimmen (z. B. Till & Busler, 2000). Die spĂ€rliche Forschung hierzu hat sich bislang mit AttraktivitĂ€t und Expertenwissen beschĂ€ftigt, das Image von Testimonial und Marke aber ĂŒberraschenderweise nicht berĂŒcksichtigt. Ein hierfĂŒr geeigneter Ansatz ist die Analyse der Persönlichkeit von Testimonial und Marke. Drei kulturĂŒbergreifend stabile Markenpersönlichkeitsdimensionen (Aufrichtigkeit, Erregung und Kultiviertheit) aus der Brand Personality Scale (Aaker, 1997) wurden in einem experimentellen Design (N = 120) unter Verwendung zweier Testimonials untersucht. Die Versuchsteilnehmenden bewerteten die Marke und das Testimonial auf denselben Persönlichkeitsdimensionen. Die Ergebnisse zeigen, dass die wahrgenommene Passung zwischen Testimonial und Marke umso höher ist, je gröĂer die Ăhnlichkeit auf den Persönlichkeitsdimensionen ist. Zudem fĂŒhrt eine hohe wahrgenommene Passung zu einem Anstieg der Kaufwahrscheinlichkeit. Implikationen fĂŒr die Anwendung in Werbekampagnen werden gegeben
Treatment of lactating sows with clofibrate as a synthetic agonist of PPARalpha does not influence milk fat content and gains of litters
BACKGROUND: In rats, it has been observed that treatment with activators of peroxisome proliferator-activated receptor a (PPARalpha) disturbs metabolic adaptations during lactation, which in turn lead to a reduction of milk fat content and gains of litters during the suckling period. It has not yet been investigated whether agonists of PPARalpha are impairing milk production of lactating sows in a similar manner as in rats. Therefore, the present study aimed to investigate the effect of treatment with clofibrate, a strong synthetic agonist of PPARalpha, on milk composition and litter gains in lactating sows.
RESULTS: Twenty lactating sows received either a basal diet (control group) or the same diet with supplementation of 2 g of clofibrate per kg of diet (clofibrate group). In the clofibrate group, mRNA concentrations of various PPARalpha target genes involved in fatty acid utilization in liver and skeletal muscle were moderately up-regulated. Fat and energy content of the milk and gains of litters during the suckling period were not different between the control group and the clofibrate group.
CONCLUSIONS: It is shown that treatment with clofibrate induces only a moderate up-regulation of PPARalpha target genes in liver and muscle of lactating sows and in turn might have limited effect on whole body fatty acid utilization. This may be the reason why clofibrate treatment did not influence milk fat content and gains of litters during the suckling period. Thus, the present study indicates that activation of PPARalpha induced either by native agonists such as dietary polyunsaturated fatty acids or a by negative energy balance might be largely uncritical in lactating sows with respect to milk production and litter gains in lactating sows
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