University of Bremen

About: University of Bremen is a education organization based out in Bremen, Germany. It is known for research contribution in the topics: Population & Glacial period. The organization has 14563 authors who have published 37279 publications receiving 970381 citations. The organization is also known as: Universität Bremen.

Electrospinning graphene quantum dots into a nanofibrous membrane for dual-purpose fluorescent and electrochemical biosensors

Abstract: Graphene quantum dots (GQDs) have become increasingly important for applications in energy materials, optical devices and biosensors. Here we report a facile technique to fabricate a nanofibrous membrane of GQDs by electrospinning water-soluble GQDs with polyvinyl alcohol (PVA) directly. The structure and fluorescence properties of the fabricated PVA/GQD nanofibrous membrane were investigated using scanning and transmission electron microscopy, and fluorescence microscopy. It was found that the electrospun PVA/GQD nanofibrous membrane has a three-dimensional structure with a high surface area to volume ratio, which is beneficial for the adsorption of electrolytes and the diffusion of reactants. For the first time, the created PVA/GQD nanofibrous membrane was utilized to fabricate dual-purpose fluorescent and electrochemical biosensors for highly sensitive determination of hydrogen peroxide (H2O2) and glucose. The experimental results indicated that the fluorescence intensity of the nanofibrous membrane decreased linearly with increasing H2O2 concentration, because the addition of H2O2 leads to fluorescence quenching of the GQDs, which endows the fabricated nanofibrous membrane with fluorescence activity. Besides, after binding glucose oxidase onto the created nanofibrous membrane, the fabricated nanofibrous membrane showed high sensitivity and selectivity for glucose detection. In addition, the PVA/GQD nanofibrous membrane can also be directly electrospun onto an electrode for electrochemical detection of H2O2. This novel nanofibrous membrane exhibits excellent catalytic performance and fluorescence activity, and therefore has potential applications for the highly stable, sensitive, and selective detection of H2O2 and glucose.

Lung cancer and cigarette smoking in Europe: An update of risk estimates and an assessment of inter‐country heterogeneity

Abstract: Ten case-control studies have been carried out in 6 European countries to investigate the major risk factors for lung cancer. Carcinogenic effect from cigarette smoke was the most relevant interest in our study, which has included 7,609 cases of lung cancer and 10,431 controls, mainly population based. The results indicate elevated odds ratios (ORs; 23.9 among men and 8.7 among women) with attributable risks exceeding 90% for men and close to 60% for women. A large, and statistically significant, variability of the results across countries was detected after adjusting for the most common confounding variables, and after controlling, at least in part, for the instability of the ORs due to the small number of non-smokers in some of the study subsets. This pattern of lung cancer risk associated with cigarettes smoke, across different European regions, reflects inherent characteristics of the studies as well as differences in smoking habits, particularly calendar periods of starting, and it is likely to have been influenced by effect modifiers like indoor radon exposure, occupation, air pollution and dietary habits.