Sampling considerations when analyzing micrometric-sized particles in a liquid jet using laser induced breakdown spectroscopy

International audiencePollution of water is a matter of concern all over the earth. Particles are known to play an important role in the transportation of pollutants in this medium. In addition, the emergence of new materials such as NOAA (Nano-Objects, their Aggregates and their Agglomerates) emphasizes the need to develop adapted instruments for their detection. Surveillance of pollutants in particulate form in waste waters in industries involved in nanopartide manufacturing and processing is a telling example of possible applications of such instrumental development. The LIBS (laser-induced breakdown spectroscopy) technique coupled with the liquid jet as sampling mode for suspensions was deemed as a potential candidate for on-line and real time monitoring. With the final aim in view to obtain the best detection limits, the interaction of nanosecond laser pulses with the liquid jet was examined. The evolution of the volume sampled by laser pulses was estimated as a function of the laser energy applying conditional analysis when analyzing a suspension of micrometric-sized particles of borosilicate glass. An estimation of the sampled depth was made. Along with the estimation of the sampled volume, the evolution of the SNR (signal to noise ratio) as a function of the laser energy was investigated as well. Eventually, the laser energy and the corresponding fluence optimizing both the sampling volume and the SNR were determined. The obtained results highlight intrinsic limitations of the liquid jet sampling mode when using 532 nm nanosecond laser pulses with suspensions

Clinical application of three-dimensional echocardiographic laser stereolithography: Effect of leaflet funnel geometry on the coefficient of orifice contraction, pressure loss and the Gorlin formula in aortic stenosis

International audienc

The electrophysiology of the betacell based on single transmembrane protein characteristics

The electrophysiology of betacells is at the origin of insulin secretion. Betacells exhibit a complex behaviour upon stimulation with glucose including repeated and uninterrupted bursting. Mathematical modelling is most suitable to improve knowledge about the function of various transmembrane currents provided the model is based on reliable data. This is the first attempt to build a mathematical model for the betacell-electrophysiology in a bottom-up approach which relies on single protein conductivity data. The results of previous whole-cell-based models are reconsidered. The full simulation including all prominent transmembrane proteins in betacells is used to provide a functional interpretation of their role in betacell-bursting and an updated vantage point of betacell-electrophysiology. As a result of a number of in silico knock-out- and block-experiments the novel model makes some unexpected predictions: Single-channel conductivity data imply that calcium-gated potassium currents are rather small. Thus, their role in burst interruption has to be revisited. An alternative role in high calcium level oscillations is proposed and an alternative burst interruption model is presented. It also turns out that sodium currents are more relevant than expected so far. Experiments are proposed to verify these predictions.Comment: 28 pages, 5 figures, 54 references, 14 pages supplementary materia

Acute type A aortic dissection in the elderly: clinical characteristics, management, and outcomes in the current era

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Microbial engineering for production of N-functionalized amino acids and amines

Mindt M, Walter T, Kugler P, Wendisch VF. Microbial engineering for production of N-functionalized amino acids and amines. Biotechnology Journal . 2020;15(7): 1900451.N‐ functionalized amines play important roles in nature and occur, for example, in the antibiotic vancomycin, the immunosuppressant cyclosporine, the cytostatic actinomycin, the siderophore aerobactin, the cyanogenic glucoside linamarin, and the polyamine spermidine. In the pharmaceutical and fine‐chemical industries N‐ functionalized amines are used as building blocks for the preparation of bioactive molecules. Processes based on fermentation and on enzyme catalysis have been developed to provide sustainable manufacturing routes to N‐ alkylated, N‐ hydroxylated, N‐ acylated, or other N‐ functionalized amines including polyamines. Metabolic engineering for provision of precursor metabolites is combined with heterologous N‐ functionalizing enzymes such as imine or ketimine reductases, opine or amino acid dehydrogenases, N‐ hydroxylases, N‐ acyltransferase, or polyamine synthetases. Recent progress and applications of fermentative processes using metabolically engineered bacteria and yeasts along with the employed enzymes are reviewed and the perspectives on developing new fermentative processes based on insight from enzyme catalysis are discussed

O fra Bernardinu Splićaninu, priređivaču prvog izdanja hrvatskog lekcionara, ponovo!

The use of miniaturised isotachophoresis to allow the simultaneous determination of two inorganic selenium species has been investigated using a poly(methyl methacrylate) chip with a 44-mm-long, 200-μm-wide, 300-μm-deep separation channel. The miniaturised device included an integrated on-column, dual-electrode conductivity detector and was used in conjunction with a hydrodynamic fluid transport system. A simple electrolyte system has been developed which allowed the separation of selenium(IV) and selenium(VI) species to be made in under 210 s. The limits of detection were calculated to be 0.52 mg L−1 for selenium(IV) and 0.65 mg L−1 for selenium(VI). The method allowed the separation of the selenium species from a range of common anions including fluoride, nitrate, nitrite, phosphate, sulfate and sulfite

Differences in Clinical Presentation, Management, and Outcomes of Acute Type A Aortic Dissection in Patients With and Without Previous Cardiac Surgery

Background— There are less data on the clinical and diagnostic imaging characteristics, management, and outcomes of patients with previous cardiac surgery (PCS) presenting with acute type A aortic dissection (AAD). Methods and Results— In 617 patients with AAD, we evaluated the differences in the clinical characteristics, management, and in-hospital outcomes of the cohorts with and without PCS. A history of PCS was present in 100 of 617 patients. Patients with PCS were more likely to be males ( P =0.02), older ( P =0.014), and to have a history of previous aortic dissection ( P <0.001) or aneurysms ( P <0.001). In contrast, PCS patients were less likely to have presenting chest pain ( P <0.001). Cardiac tamponade was less common in PCS patients ( P =0.007). Fewer AAD patients with PCS underwent surgical repair ( P =0.001). Hospital mortality was not adversely influenced by PCS (odds ratio [OR], 1.46; 95% confidence interval [CI], 0.81 to 2.63), but a trend for increased death was seen in patients with previous aortic valve replacement (AVR) (OR, 2.31; 95% CI, 0.98 to 5.43). Age70 years or older, previous AVR, shock, and renal failure identified PCS patients at risk for death. Conclusions— Our study highlights differences in clinical characteristics, management, and outcomes of AAD patients with PCS. Importantly, PCS, with the exception of previous AVR, does not adversely influence early outcomes of AAD patients, including those undergoing surgical repair. However, because of otherwise dismal outcomes with medical management of AAD, our data indicate that a history of PCS (even that of previous AVR) should not preclude physicians from recommending surgical correction of type A aortic dissection in appropriate patients