Separation of proteolytic enzymes originating from Antarctic krill (Euphausia superba) by capillary electrophoresis

The viscosity-adjustable property of F127 block copolymer PEO99PPO69PEO99, PEO and PPO being poly(ethylene oxide) and poly(propylene oxide), respectively, was found to be useful for the development of automated capillary electrophoresis (CE). The polymer solution can form a gel-like structure with sieving ability and can also serve as a dynamic coating material, thereby effectively suppressing the electroosmotic flow induced by the ionization of the silanol group on the quartz capillary inner wall. When applied to CE as a separation medium, F127 block copolymer can provide the advantages of high separation resolution, easy injection and replacement of the triblock copolymer solution and convenient capillary column treatment. High reproducibility of DNA electrophoretic migration time in CE by replenishing F127 solution in acid-washed capillary tubings can be achieved. The relative standard deviation of the DNA migration time is less than 2%. In the investigation of F127 concentration and temperature effects on the performance of DNA separation in CE, we have found that the DNA electrophoretic migration behavior in the F127 gel-like solution cannot be described by any one of the existing models.     

Mathland: The Role of Mathematics in Virtual Architecture

This paper is dedicated to some arguments that could be of interest both for students and practicing architects. A short adventure in the reign of mathematics and culture. The example that I have chosen is that of the idea of space, how this idea and the perception of space around us has changed up to the point where it has arrived to the form of virtual architecture.     

Radial modulation of single microbubbles

Radial modulation imaging is a new promising technique to improve contrast-enhanced ultrasound images. The method is based on dual-frequency insonation of contrast agent microbubbles. A low-frequency (LF) pulse is used to modulate the responses of the microbubbles to a high-frequency (HF) imaging pulse. Inverting the LF pulse induces amplitude and phase differences in the HF response of contrast agent microbubbles, which can be detected using Doppler techniques. Although the technique has been successfully implemented, no consensus persists on parameter choice and resulting effects. In a separate study, "compression-only" behavior of coated microbubbles was observed. Compression-only behavior could be beneficial for radial modulation imaging. This was investigated using high-speed camera recordings and simulations. We recorded the vibrations of 78 single microbubbles in a dual-frequency ultrasound field. The results showed that the LF pulse induced significant compression-only behavior, which for microbubble sizes below and at HF resonance resulted in high radial amplitude modulation. It, however, also appeared that, for radial modulation imaging, microbubble size is more important than resonance and compression-only effects.     

Increasing the Endothelial Layer Permeability Through Ultrasound-Activated Microbubbles

Drug delivery to a diseased tissue will be more efficient if the vascular endothelial permeability is increased. Recent studies have shown that the permeability of single cell membranes is increased by ultrasound in combination with contrast agents. It is not known whether this combination can also increase the permeability of an endothelial layer in the absence of cell damage. To investigate the feasibility of controlled increased endothelial layer permeability, we treated monolayers of human umbilical vein endothelial cells with ultrasound and the contrast agent BR14. Barrier function was assessed by measuring transendothelial electrical resistance (TEER). Ultrasound-activated BR14 significantly decreased TEER by 40.3%$,pm,$3.7% ( $p ≪ 0.01$). After treatment, no cell detachment or damage was observed. In conclusion, ultrasound-activated BR14 microbubbles increased the endothelial layer permeability. This feature can be used for future ultrasound-guided drug delivery systems.      

Conducting filaments and voltage-controlled negative resistance in Al-Al2O3-Au structures with amorphous dielectric

The dependence of the forming process and of the voltage-controlled negative resistance (VCNR) on the temperature and pressure of an ambient gas (particularly O₂) have been studied in Al-Al₂O₃-Au sandwich structures. It was found that both these quantities have the same effect on the behaviour of the structures. During the forming process, the formation of many local defects, which can be regarded as conducting channels of a specific character, was detected on the surface of the samples. Their connection with VCNR was proved. Electron emission investigations further proved that at low voltages of both polarities the electrons are emitted only from these defects. At a sufficiently high voltage of normal polarity (Al-, Au+), an additional emission from the whole of the active surface of the samples was found. Our explanation of the experimental results obtained is based on the assumption that the electrical properties of the above-mentioned conduction channels depend mainly on the voltage-stimulated adsorption of ambient oxygen.     

Studies on the germination specific α-amylase and its inhibitor of rye (Secale cereale) 3. Estimation of a-amylase inhibitor activity

Summary A method is presented for estimating the -amylase II inhibitor activity in rye and isolated preparations (inhibition of germination-specific -amylase II from germinated rye). It was established that the residual activity of -amylase activity did not decrease linearly but was retarded in dependence on the inhibitor concentration. A plot of the reciprocal of the-amylase II residual activity in dependence on the inhibitor/-amylase II mass ratio showed linearity up to 50% residual activity. From this, an estimation method has been derived. Further, a computer program has been developed to calculate the results. Finally a simplified procedure (two-point method) is proposed in order to rationalize the application. The formation of the enzyme-inhibitor complex is complete after 10 min at 35° C and a preincubation time of no more than 15 min is needed before determining the inhibitor activity. The method has been found to be convenient for the inhibitor analysis of the cereal grain, flour and purified fractions and the characterization of the -amylase II inhibitor.

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Untersuchungen zur keimungsspezifischen -Amylase und deren Inhibitor im Roggen (Secale cereale) 3. Bestimmung der -Amylase-Inhibitor-Aktivität

Zusammenfassung Es wird eine Methode zur Bestimmung der -Amylase-II-Inhibitor-Aktivität in Roggen sowie daraus isolierten Präparaten (Hemmung der keimungsspezifischen -Amylase-II aus gekeimtem Roggen) vorgestellt. Bei den Untersuchungen wird festgestellt, daß die -Amylase-II-Restaktivität mit steigendem Inhibitorzusatz nicht linear, sondern von Anfang an verzögert abnimmt. Bei reziproker Darstellung der -Amylase-II-Restaktivität gegen das Inhibitor--Amylase-II-Verhältnis besteht bis etwa 50% Restaktivität Linearität. Hieraus wird ein Bestimmungsverfahren abgeleitet. Die Berechnung erfolgt über ein speziell entwickeltes Computerprogramm. Ferner wird ein vereinfachtes Verfahren (Zwei-Punkt-Methode) vorgeschlagen, um seine Anwendung zu rationalisieren. Die Ausbildung eines stabilen Enzym-Inhibitor-Komplexes ist bei 35 °C bereits nach 10 min abgeschlossen, so daß vor der Bestimmung der Inhibitor-Aktivität eine Präinkubationszeit von 15 min ausreicht. Das Verfahren hat sich bei Untersuchungen zur Reinigung und Charakterisierung von -Amylase-II-Inhibitoren aus Roggen bewährt (vgl. 2. Mitt.).

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Explanation of symbols used for calculation A -amylase II activity (U/g) without inhibitor addition;A=1/Y - A(I) -amylase II activity in the presence of inhibitor (U/g);A (I)=O(I)·F·D/(C·t·0.1) - AI -amylase II inhibitor activity (IU/g);AI=0.5·A/X - B regression coefficient [(g amylase/U)/(g inhibitor/g amylase];B=Y/X - C -amylase II mass (g) - D -amylase II dilution (ml); volume to whichC was diluted - E -amylase II in test volume (g/0.1 ml);E=C·0.1/D - F factor for calculating maltose equivalents from the calibration curve (mol maltose) - I designation of measured values (no.) - IU inhibitor unit - J(I) inhibitor mass (g) - K(I) inhibitor dilution (ml); volume to whichJ (I) was diluted - L(I) inhibitor in test volume (g/0.1 ml);L(I)=J(I)·0.1/K(I) - N number of measured values - O(I) absorbance at 530 nm in 1-cm cell - P(I) -amylase II activity (%), relative toA(I)=-amylase II activity without inhibitor addition=100%;P(I)=A (I)·100/A(I) - R correlation coefficient - t incubation time (min); t=15 min - U -amylase II activity unit - X inhibitor/-amylase II mass ratio at 50% residual activity;X=Y/B - X(I) inhibitor/-amylase II mass ratio;X(I)=L(I)/E - Y reciprocal -amylase II activity (g/U) without inhibitor addition, calculated from the regression equation;Y(I)=Y+B·X(I);Y=1/A - Y(I) reciprocal -amylase II activity;Y (I)=1/A(I)=C·t·0.1/[O(I)·F·D]     

The careers behind and the impact of solo author articles in Nature and Science

Scientometrics - Nature and Science—the top ranked, high impact multidisciplinary scientific journals with considerably low acceptance rate below 10%. As such, publication in these is...