High‐throughput continuous flow femtosecond laser‐assisted cell optoporation and transfection

We present a femtosecond‐laser based nanoprocessing system for transient optical cell membrane poration to allow the introduction of foreign molecules into the interior of a cell with very high throughput. In the setup, cells flow through a micro‐flow tube for spatial confinement and are simultaneously targeted by fs laser radiation. Beam‐shaping generates a focal geometry along a line which is scanned across the micro‐flow cell to increase the number of reachable cells. Successful cell membrane poration was observed indirectly by cell transfection even with cell‐light interaction times in the millisecond range. The system was characterized by experiments with Chinese hamster ovary cells regarding cell viability, the uptake of extrinsic molecules and cell transfection efficiency. The continuous flow of cells enables a tremendous increase of cell throughput compared to previous nonflow approaches by treating millions of cells, although with only limited efficiency. The setup opens the possibility to realize a completely automated high‐throughput laser‐assisted cell‐poration system which could be integrated in lab‐on‐a‐chip devices. Microsc. Res. Tech. 77:974–979, 2014. © 2014 Wiley Periodicals, Inc.     

Measurement of N2, N2O, NO, and CO2 emissions from soil with the gas-flow-soil-core technique

Here we describe a newly designed system with three stand-alone working incubation vessels for simultaneous measurements of N(2), N(2)O, NO, and CO(2) emissions from soil. Due to the use of a new micro thermal conductivity detector and the redesign of vessels and gas sampling a so-far unmatched sensitivity (0.23 μg N(2)-N h(-1) kg(-1) ds or 8.1 μg N(2)-N m(-2) h(-1)) for detecting N(2) gas emissions and repeatability of experiments could be achieved. We further tested different incubation methods to improve the quantification of N(2) emission via denitrification following the initialization of soil anaerobiosis. The best results with regard to the establishment of a full N balance (i.e., the changes in mineral N content being offset by simultaneous emission of N gases) were obtained when the anaerobic soil incubation at 25 °C was preceded by soil gas exchange under aerobic conditions at a lower incubation temperature. The ratios of N and C gas emission changed very dynamically following the initialization of anaerobiosis. For soil NO(3)(-) contents of 50 mg N kg(-1) dry soil (ds) and dissolved organic carbon (DOC) concentrations of approximately 300 mg C kg(-1) ds, the cumulative emissions of N(2), N(2)O, and NO were 24.3 ± 0.1, 12.6 ± 0.4, and 10.1 ± 0.3 mg N kg(-1) ds, respectively. Thus, N gas emissions accounted (on average) for 46.2% (N(2)), 24.0% (N(2)O), and 19.2% (NO) of the observed changes in soil NO(3)(-). The maximum N(2) emission reached 1200 μg N h(-1) kg(-1) ds, whereas the peak emissions of N(2)O and NO were lower by a factor of 2-3. The overall N(2):N(2)O and NO:N(2)O molar ratios were 1.6-10.0 and 1.6-2.3, respectively. The measurement system provides a reliable tool for studying denitrification in soil because it offers insights into the dynamics and magnitude of gaseous N emissions due to denitrification under various incubation conditions.     

Ein Konzept für den Traglastnachweis gurtgelagerter doppeltsymmetrischer I‐Träger unter Berücksichtigung der Profilverformung

Biegeträger aus I‐Profilen werden aus verschiedenen Gründen ohne Auflagersteifen, also nur an den Gurten gelagert, ausgeführt. Dabei wird die Stabilität gegen das Biegedrillknicken dieser Träger durch Profilverformung in den Auflagerbereichen vermindert, was die gängigen Nachweisformeln und Hilfsmittel in der Regel nicht berücksichtigen. In diesem Aufsatz werden die Ergebnisse einer Dissertation vorgestellt, in der durch analytische Betrachtungen ein Ersatzmodell zur Ermittlung der Verzweigungslast abgeleitet wurde. Durch experimentelle und numerische Traglastuntersuchungen wurden Traglastkurven entwickelt, so dass ein praxisnahes Nachweiskonzept für gurtgelagerte Träger vorgestellt werden kann. A model for the determination of the ultimate load of doublesymmetric I‐shaped beams on seats considering distortional effects. For several reasons, I‐shaped beams are built without stiffeners at the bearings, and because of this they are seated on one flange only. The stability against lateral torsional buckling of these beams is therefore reduced by distortional effects that occur close to the bearings, but this is normally not taken into account by the common design‐formulae and guidelines. This article presents the results of a doctoral thesis where an analogous model for the determination of buckling‐loads has been derived. By experimental and numerical investigations buckling curves for the determination of ultimate loads have been developed, in order to provide a design concept for beams on seats.     

Exakte U‐Werte von Stahlbeton‐Sandwichelementen

Zur genauen Ermittlung der Wärmeverluste über die Hüllfläche eines Gebäudes unter stationären Randbedingungen ist — neben anderen Kennwerten — die möglichst exakte Bestimmung der Wärmedurchgangskoeffizienten (U‐Werte) der Fassadenflächen notwendig. Für Fassaden aus Stahlbeton‐Sandwichelementen ist der U‐Wert dabei aus den homogenen Einzelschichten in Verbindung mit den zusätzlichen Wärmeverlusten infolge der systembedingt vorhandenen Anker‐ und Fugensysteme zu bestimmen. üblicherweise werden dazu vereinfacht Pauschalzuschläge angenommen, die zwar das Berechnungsverfahren deutlich vereinfachen, jedoch zu verfälschten Ergebnissen und in der Regel darüber hinaus auch zu ökonomisch ungünstigen Ergebnisse führen. Vor diesem Hintergrund wird im Folgenden ein praxistaugliches Berechnungsverfahren vorgestellt, das die genaue Erfassung der Wärmeverluste aus Anker‐ und Fugensystemen sowohl für individuelle Elementkonfigurationen als auch für beliebig gestaltete Fassaden ermöglicht und damit zu exakten U‐Werten führt. Precise U‐values of precast concrete sandwich panels. For the exact determination of the heat losses over the building envelope with static boundary conditions it is necessary to determine — besides other parameters — the thermal transmittance (U‐value) of the exterior walls as accurate as possible. The U‐value of precast concrete sandwich panels is quantified on the one hand out of the homogeneous layering of the three sandwich components and on the other hand out of the additional thermal losses of different anchor and joint systems. Usually simplified additions are assumed, which obviously simplify the computation method but generally lead to economically unfavorable results. With this in mind, a practice‐suited computation method is presented which enables the exact examination of additional heat losses for anchor and joint systems for individual element configurations as well as the whole facade system and therefore leads to accurate U‐values.     

Development of an (S)-1-{2-[tris(4-methoxyphenyl)methoxy]ethyl}piperidine-3-carboxylic acid [(S)-SNAP-5114] carba analogue inhibitor for murine γ-aminobutyric acid transporter type 4

A series of GABA uptake inhibitors related to (S)-1-{2-[tris(4-methoxyphenyl)methoxy]ethyl}piperidine-3-carboxylic acid [(S)-SNAP-5114], the most potent mGAT4 inhibitor known so far, were synthesized and biologically evaluated for their inhibitory potency at the four GABA uptake transporters mGAT1-4 stably expressed in HEK-293 cell lines. New analogues were developed with potencies that are similar to or slightly higher than those of current mGAT4 inhibitors, but with distinctly improved chemical stability. (S)-Nipecotic acid derivatives possessing a 2-[1-(4-methoxy-2-methylphenyl)-1,1-bis(4-methoxyphenyl)methoxy]ethyl (DDPM-859) or a 4,4,4-tris(4-methoxyphenyl)but-2-en-1-yl moiety (DDPM-1457) were found to exhibit pIC(50) values of 5.78 and 5.87, respectively. Thus, as mGAT4 inhibitors, these compounds compare well with (S)-SNAP-5114 (pIC(50) =5.71), but are far more stable than the latter. Moreover, DDPM-859 displays a more favorable subtype selectivity for mGAT4 versus mGAT3 than does (S)-SNAP-5114.     

Effects of inland nitrogen transport and attenuation modeling on coastal nitrogen load abatement

Modeling of the spatial distribution of nitrogen transport and attenuation from various inland sources and along different hydrological pathways to coastal waters is needed for relevant decisions on effective allocation of measures for coastal nitrogen load abatement. We identify, classify, and quantify uncertainties associated with main discrepancies between spatial process representations in different catchment-scale nitrogen transport-attenuation models. The results show important model differences, indicating scientific disagreement on the realistic spatial process understanding, representation, and quantification in nitrogen transport-attenuation modeling. By further developing solutions for economic optimization of spatially differentiated nitrogen source abatement in coastal catchments, we find this disagreement to considerably affect the economic efficiency of coastal nitrogen load reduction. It may also lead to stakeholder mistrust and conflict and needs to be recognized and handled in environmental policy.     

Effect of ZrO2 addition on the mechanical properties of porous TiO2 bone scaffolds

This study aimed at the investigation of the effect of zirconium dioxide (ZrO₂) addition on the mechanical properties of titanium dioxide (TiO₂) bone scaffolds. The highly biocompatible TiO₂ has been identified as a promising material for bone scaffolds, whereas the more bioinert ZrO₂ is known for its excellent mechanical properties. Ultra-porous TiO₂ scaffolds (> 89% porosity) were produced using polymer sponge replication with 0–40 wt.% of the TiO₂ raw material substituted with ZrO₂. Microstructure, chemical composition, and pore architectural features of the prepared ceramic foams were characterised and related to their mechanical strength. Addition of 1 wt.% of ZrO₂ led to 16% increase in the mean compressive strength without significant changes in the pore architectural parameters of TiO₂ scaffolds. Further ZrO₂ additions resulted in reduction of compressive strength in comparison to containing no ZrO₂. The appearance of zirconium titanate (ZrTiO₄) phase was found to hinder the densification of the ceramic material during sintering resulting in poor intergranular connections and thus significantly reducing the compressive strength of the highly porous ceramic foam scaffolds.     

Motion of inertial particles in Gaussian fields driven by an infinite-dimensional fractional Brownian motion

We study the motion of an inertial particle in a fractional Gaussian random field. The motion of the particle is described by Newton's second law, where the force is proportional to the difference between the background fluid velocity and the particle velocity. The fluid velocity satisfies a linear stochastic partial differential equation driven by an infinite-dimensional fractional Brownian motion with an arbitrary Hurst parameter H?∈?(0,?1). The usefulness of such random velocity fields in simulations is that we can create random velocity fields with desired statistical properties, thus generating artificial images of realistic turbulent flows. This model also captures the clustering phenomenon of preferential concentration, observed in real world and numerical experiments, i.e. particles cluster in regions of low-vorticity and high-strain rate. We prove almost sure existence and uniqueness of particle paths and give sufficient conditions to rewrite this system as a random dynamical system with a global random pullback attractor. Finally, we visualize the random attractor through a numerical experiment.