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Formation mechanism for stable hybrid clusters of proteins and nanoparticles
Citrate-stabilized gold nanoparticles (AuNP) agglomerate in the presence of hemoglobin (Hb) at acidic pH. The extent of agglomeration strongly depends on the concentration ratio [Hb]/[AuNP]. Negligible agglomeration occurs at very low and very high [Hb]/[AuNP]. Full agglomeration and precipitation occur at [Hb]/[AuNP] corresponding to an Hb monolayer on the AuNP. Ratios above and below this value lead to the formation of an unexpected phase: stable, microscopic AuNP–Hb agglomerates. We investigated the kinetics of agglomeration with dynamic light scattering and the adsorption kinetics of Hb on planar gold with surface-acoustic wave-phase measurements. Comparing agglomeration and adsorption kinetics leads to an explanation of the complex behavior of this nanoparticle–protein mixture. Agglomeration is initiated either when Hb bridges AuNP or when the electrostatic repulsion between AuNP is neutralized by Hb. It is terminated when Hb has been depleted or when Hb forms multilayers on the agglomerates that stabilize microscopic clusters indefinitely.
Dynamic publication formats and collaborative authoring
While Online Publishing has replaced most traditional printed journals in less than twenty years, today’s Online Publication Formats are still closely bound to the medium of paper. Collaboration is mostly hidden from the readership, and ‘final’ versions of papers are stored in ‘publisher PDF’ files mimicking print. Meanwhile new media formats originating from the web itself bring us new modes of transparent collaboration, feedback, continued refinement, and reusability of (scholarly) works: Wikis, Blogs and Code Repositories, to name a few. This chapter characterizes the potentials of Dynamic Publication Formats and analyzes necessary prerequisites. Selected tools specific to the aims, stages, and functions of Scholarly Publishing are presented. Furthermore, this chapter points out early examples of usage and further development from the field. In doing so, Dynamic Publication Formats are described as (a) a ‘parallel universe’ based on the commodification of (scholarly) media, and (b) as a much needed complement, slowly recognized and incrementally integrated into more efficient and dynamic workflows of production, improvement, and dissemination of scholarly knowledge in general.
Analysis of fatty acids and triacylglycerides by Pd nanoparticle-assisted laser desorption/ionization mass spectrometry
In this study, we propose a simple and rapid technique for characterization of free fatty acids and triacylglycerides (TAG) based on palladium nanoparticular (Pd-NP) surface-assisted laser desorption/ionization (SALDI) mass spectrometry (MS). The implemented Pd-NP material allowed detection of free fatty acids and TAGs exclusively as [M + K]+ ions in positive ion mode. Under negative ionization conditions, unusual trimetric structures were generated for free fatty acids, while TAGs underwent irreproducible degradation reactions. Importantly, the mass spectra obtained from Pd-NP targets in positive ion mode were very clean without interferences from matrix-derived ions in the low m/z range and readily enabled the detection of intact TAGs in vegetable oils without major fragmentation reactions as compared to conventional MALDI-MS, requiring only a minimal amount of sample preparation.
Payload charging events in the mesosphere and their impact on Langmuir type electric probes
Three sounding rockets were launched from Andøya Rocket Range in the ECOMA campaign in December 2010. The aim was to study the evolution of meteoric smoke particles during a major meteor shower. Of the various instruments onboard the rocket payload, this paper presents the data from a multi-Needle Langmuir Probe (m-NLP) and a charged dust detector. The payload floating potential, as observed using the m-NLP instrument, shows charging events on two of the three flights. These charging events cannot be explained using a simple charging model, and have implications towards the use of fixed bias Langmuir probes on sounding rockets investigating mesospheric altitudes. We show that for a reliable use of a single fixed bias Langmuir probe as a high spatial resolution relative density measurement, each payload should also carry an additional instrument to measure payload floating potential, and an instrument that is immune to spacecraft charging and measures absolute plasma density.
Overview of Chinese specialist literature in the field of Science and Technology in Germany
The main target audience of the libraries special collections of East Asian literature is the scholars of humanities and social sciences, just like the sinological libraries are normally considered for the scholars of Chinese Studies. But in recent years one can notice a growing interest in East Asia, especially in China, in the field of science and technology. The increasing international economic relations between China and Germany are raising the demand for engineers who have a broad knowledge of China and the technical developments of both countries. In order to achieve an overview of the rapid technical and scientific developments in China, it is assumed that specialized language skills are required to be able to access important information. As the National Library for all areas of engineering and natural sciences, the German National Library of Science and Technology (TIB) takes the responsibility to provide research and industry with specialist literature and information – nationally and internationally. Therefore the TIB also built up the most comprehensive collection of modern Chinese literature in science and technology in Germany. As to understand how the library can provide a good support for the much more heterogeneous user group of Chinese literature in this field as well, it is necessary to learn more about their requirements. The purpose of this paper is to get an overview of the Chinese research output in science and technology by analyzing international databases, and to examine the target audience of this kind of literature. It is expected that it will not only show the growing awareness and use of Chinese technical and scientific publications by engineers in Germany, but also demonstrate the importance of access to these publications in terms of scholarly exchange for both German and Chinese scholars in Germany.
Assessment of continuous vaginal logger-based temperature monitoring in fever-induced gilts
The aim of this study was to identify a low risk method to induce fever in gilts and to evaluate vaginal sensors for temperature monitoring. Therefore, a rhinitis atrophicans vaccine was used to induce fever to evaluate sensors and behavioral patterns. During 11 trials, two of four animals were injected with 2 mL of the vaccine Porcilis AR-T DF (Intervet) and the other two animals were treated with 2 mL of 0.9% NaCl as controls. A temperature logger (TRIX-8, LogTag Recorders, Auckland, New Zealand) was used to continuously monitor the vaginal temperature. Additionally, rectal temperatures were measured four times daily. The water consumption, food intake and locomotion behaviors of the animals were analysed one day before treatment and during the day of the treatment. The vaccine induced fever in all gilts, which occurred approximately 5.87 h after vaccination. The vaginal logger temperatures and the rectal temperatures showed a linear correlation in 21 vaccinated gilts (r = 0.86; p<0.0001) and 22 non-vaccinated gilts (r = 0.65; P<0.0001). The vaginal logger can be continuously used to measure the core temperature. Water intake decreased (p<0.0001) in the gilts with fever, whereas food intake did not change (p = 0.9411). The vaccinated gilts spent 79±16 more minutes per day lying after the vaccination (p<0.001) in comparison to the day before the vaccination. Treatment with this vaccine provides the opportunity to induce fever over a short time period (5.13 h) and mild sickness behavior in gilts to investigate disease indicators.
Roles of hydrogenation, annealing and field in the structure and magnetic entropy change of Tb-based bulk metallic glasses
The reduction of open-volume regions in Tb-based metallic glass (MG) by annealing and hydrogen charging was found to rearrange the atomic structure and tune the magnetic behaviors. After crystallization, the magnetic structure and magnetic entropy change (MEC) alters due to the structural transformation, and a plateau-like-MEC behavior can be obtained. The hydrogen concentration after charging at 1mA/cm2 for 576 h reaches as high as 3290 w-ppm. The magnetization behavior and the MEC change due to the modification of the exchange interaction and the random magnetic anisotropy (RMA) upon hydrogenation. At low temperatures, irreversible positive MEC was obtained, which is related to the internal entropy production. The RMA-to-exchange ratio acts as a switch to control the irreversible entropy production channel and the reversible entropy transfer channel. The field dependence of the MEC is discussed in term of the competition among Zeeman energy, exchange interaction and RMA.
Surviving the surf: The tribomechanical properties of the periostracum of Mytilus sp
We investigated the friction and wear behavior as well as the mechanical properties of the periostracum of Mytilus sp. Tribological properties were determined with a reciprocal sliding microtribometer, while mechanical characterization was performed using a nanoindenter. Measurements were performed in dry and wet conditions. On the dry periostracum we found a low friction coefficient of 0.078 ± 0.007 on the young parts and a higher one of 0.63 ± 0.02 on the old parts of the shell. Under wet, saline, conditions we only observed one average coefficient of friction of 0.37 ± 0.01. Microscopic ex situ analysis indicated that dry periostracum wore rather rapidly by plowing and fatigue, while it exhibited a high wear resistance when immersed in salt water. The Young’s modulus and hardness of the periostracum were also investigated in both dry and wet conditions. Under dry conditions the Young’s modulus of the periostracum was 8 ± 3 GPa, while under wet conditions it was 0.21 ± 0.05 GPa. The hardness of dry periostracum samples was 353 ± 127 MPa, whereas the hardness of wet samples was 5 ± 2 MPa. It was found that, in the wet state, viscous behavior plays a significant role in the mechanical response of the periostracum. Our results strongly indicate that the periostracum can provide an important contribution to the overall wear resistance of Mytilus sp. shell.
Label free sensing of creatinine using a 6 GHz CMOS near-field dielectric immunosensor
In this work we present a CMOS high frequency direct immunosensor operating at 6 GHz (C-band) for label free determination of creatinine. The sensor is fabricated in standard 0.13 μm SiGe:C BiCMOS process. The report also demonstrates the ability to immobilize creatinine molecules on a Si3N4 passivation layer of the standard BiCMOS/CMOS process, therefore, evading any further need of cumbersome post processing of the fabricated sensor chip. The sensor is based on capacitive detection of the amount of non-creatinine bound antibodies binding to an immobilized creatinine layer on the passivated sensor. The chip bound antibody amount in turn corresponds indirectly to the creatinine concentration used in the incubation phase. The determination of creatinine in the concentration range of 0.88–880 μM is successfully demonstrated in this work. A sensitivity of 35 MHz/10 fold increase in creatinine concentration (during incubation) at the centre frequency of 6 GHz is gained by the immunosensor. The results are compared with a standard optical measurement technique and the dynamic range and sensitivity is of the order of the established optical indication technique. The C-band immunosensor chip comprising an area of 0.3 mm2 reduces the sensing area considerably, therefore, requiring a sample volume as low as 2 μl. The small analyte sample volume and label free approach also reduce the experimental costs in addition to the low fabrication costs offered by the batch fabrication technique of CMOS/BiCMOS process.
Stimuli‐responsive microjets with reconfigurable shape
Flexible thermoresponsive polymeric microjets are formed by the self‐folding of polymeric layers containing a thin Pt film used as catalyst for self‐propulsion in solutions containing hydrogen peroxide. The flexible microjets can reversibly fold and unfold in an accurate manner by applying changes in temperature to the solution in which they are immersed. This effect allows microjets to rapidly start and stop multiple times by controlling the radius of curvature of the microjet. This work opens many possibilities in the field of artificial nanodevices, for fundamental studies on self‐propulsion at the microscale, and also for biorelated applications.