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41.
Monika Mueller Maybelle Q. T. Loh Doris H. Y. Tee Yuansheng Yang Alois Jungbauer 《Applied biochemistry and biotechnology》2013,169(4):1431-1448
Proteins like immunoglobulin (IgGs) are prone to degradation by a variety of pathways. In this study, a stabilizing formulation for long-term storage of a panel of seven monoclonal IgGs was found using differential scanning calorimetry (DSC). In the chosen formulations, the IgGs were subjected to stress, accelerated and real-time storage, and analyzed by size exclusion chromatography to determine fragment and aggregate content, and fluorescence-activated cell sorting to measure immunoreactivity. All IgGs showed the greatest conformational stability near their isoelectric point which was enhanced by adding sorbitol, sucrose, glycine, and sodium chloride. Optimized formulations, found by DSC, containing 20 % sorbitol and 1 M glycine prevented IgG aggregation and fragmentation and conserved immunoreactivity against shear stress, multiple freeze–thaw cycles, accelerated storage at 37 °C, and 12 months storage at 4 and ?20 °C. Relatively poor thermal stability of the antigen-binding fragment domain was shown to limit storage stability of IgGs. This study confirms the predictive power of DSC to find storage formulations which protect IgGs during stress and long-term storage from aggregation and degradation. Liquid formulations found in this study may have a broad utility for other IgGs. 相似文献
42.
Larissa Mueller Heike Traub Norbert Jakubowski Daniela Drescher Vladimir I. Baranov Janina Kneipp 《Analytical and bioanalytical chemistry》2014,406(27):6963-6977
The analysis of single cells is a growing research field in many disciplines such as toxicology, medical diagnosis, drug and cancer research or metallomics, and different methods based on microscopic, mass spectrometric, and spectroscopic techniques are under investigation. This review focuses on the most recent trends in which inductively coupled plasma mass spectrometry (ICP-MS) and ICP optical emission spectrometry (ICP-OES) are applied for single-cell analysis using metal atoms being intrinsically present in cells, taken up by cells (e.g., nanoparticles), or which are artificially bound to a cell. For the latter, especially element tagged antibodies are of high interest and are discussed in the review. The application of different sample introduction systems for liquid analysis (pneumatic nebulization, droplet generation) and elemental imaging by laser ablation ICP-MS (LA-ICP-MS) of single cells are highlighted. Because of the high complexity of biological systems and for a better understanding of processes and dynamics of biologically or medically relevant cells, the authors discuss the idea of “multimodal spectroscopies.” 相似文献
43.
Oleg B. Shchekin Peter J. Schmidt Fahong Jin Nate Lawrence Kenneth J. Vampola Helmut Bechtel Danielle R. Chamberlin Gerd O. Mueller 《固体物理学:研究快报》2016,10(4):310-314
Droop, the decrease of efficiency with increased power density, became a major topic with InGaN LEDs, after its introduction in 2007. This paper provides insight into droop in localized center luminescence phosphors, exemplified here by Eu2+ doped materials. This topic is of increasing importance, as high brightness blue LEDs have reached outputs >1 W/mm2. The nonlinearities in phosphor quantum efficiency result in drive‐dependent color point shift and reduction of overall efficiency of phosphor converted white LEDs which utilize Eu2+ activated phosphors. The efficiency quenching can be traced back to two processes, well‐known in laser physics, excited state absorption or/and cross relaxation by Foerster/Dexter transfer. Both processes lead to reduction in phosphor efficiency, but they can be differentiated. Understanding the root cause of efficiency quenching opens ways to minimize the practical consequences. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
44.
Vaman C Andreoiu C Bazin D Becerril A Brown BA Campbell CM Chester A Cook JM Dinca DC Gade A Galaviz D Glasmacher T Hjorth-Jensen M Horoi M Miller D Moeller V Mueller WF Schiller A Starosta K Stolz A Terry JR Volya A Zelevinsky V Zwahlen H 《Physical review letters》2007,99(16):162501
Rare isotope beams of neutron-deficient 106,108,110Sn from the fragmentation of 124Xe were employed in an intermediate-energy Coulomb excitation experiment. The measured B(E2,0(1)(+)-->2(1)(+)) values for 108Sn and 110Sn and the results obtained for the 106Sn show that the transition strengths for these nuclei are larger than predicted by current state-of-the-art shell-model calculations. This discrepancy might be explained by contributions of the protons from within the Z = 50 shell to the structure of low-energy excited states in this region. 相似文献
45.
Excellent passivation of thin silicon wafers by HF‐free hydrogen plasma etching using an industrial ICPECVD tool 下载免费PDF全文
Muzhi Tang Jia Ge Johnson Wong Zhi Peng Ling Torsten Dippell Zhenhao Zhang Marco Huber Manfred Doerr Oliver Hohn Peter Wohlfart Armin Gerhard Aberle Thomas Mueller 《固体物理学:研究快报》2015,9(1):47-52
In this work, hydrogen plasma etching of surface oxides was successfully accomplished on thin (~100 µm) planar n‐type Czochralski silicon wafers prior to intrinsic hydrogenated amorphous silicon [a‐Si:H(i)] deposition for heterojunction solar cells, using an industrial inductively coupled plasma‐enhanced chemical vapour deposition (ICPECVD) platform. The plasma etching process is intended as a dry alternative to the conventional wet‐chemical hydrofluoric acid (HF) dip for solar cell processing. After symmetrical deposition of an a‐Si:H(i) passivation layer, high effective carrier lifetimes of up to 3.7 ms are obtained, which are equivalent to effective surface recombination velocities of 1.3 cm s–1 and an implied open‐circuit voltage (Voc) of 741 mV. The passivation quality is excellent and comparable to other high quality a‐Si:H(i) passivation. High‐resolution transmission electron microscopy shows evidence of plasma‐silicon interactions and a sub‐nanometre interfacial layer. Using electron energy‐loss spectroscopy, this layer is further investigated and confirmed to be hydrogenated suboxide layers. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
46.
Valerie Derpmann David Mueller Iustinian Bejan Hannah Sonderfeld Sonja Wilberscheid Ralf Koppmann Klaus J. Brockmann Thorsten Benter 《Journal of the American Society for Mass Spectrometry》2014,25(3):329-342
We report on a novel method for atmospheric pressure ionization of compounds with elevated electron affinity (e.g., nitroaromatic compounds) or gas phase acidity (e.g., phenols), respectively. The method is based on the generation of thermal electrons by the photo-electric effect, followed by electron capture of oxygen when air is the gas matrix yielding O2 – or of the analyte directly with nitrogen as matrix. Charge transfer or proton abstraction by O2 – leads to the ionization of the analytes. The interaction of UV-light with metals is a clean method for the generation of thermal electrons at atmospheric pressure. Furthermore, only negative ions are generated and neutral radical formation is minimized, in contrast to discharge- or dopant assisted methods. Ionization takes place inside the transfer capillary of the mass spectrometer leading to comparably short transfer times of ions to the high vacuum region of the mass spectrometer. This strongly reduces ion transformation processes, resulting in mass spectra that more closely relate to the neutral analyte distribution. cAPECI is thus a soft and selective ionization method with detection limits in the pptV range. In comparison to standard ionization methods (e.g., PTR), cAPECI is superior with respect to both selectivity and achievable detection limits. cAPECI demonstrates to be a promising ionization method for applications in relevant fields as, for example, explosives detection and atmospheric chemistry. Figure
? 相似文献
47.
M.-S. Lee K.S. Han J. Lee Y. Shin T.C. Kaspar Y. Chen M.H. Engelhard K.T. Mueller V. Murugesan 《Materials Today Chemistry》2020
Surface reactivity and ion transfer processes of anatase TiO2 nanocrystals were studied using lithium bis(trifluoromethylsulfone)imide (LiTFSI) as a probing molecule. Analysis of synthesized anatase TiO2 by electron microscopy reveals aggregated nanoparticles (average size ~8 nm) with significant defects (holes and cracks). With the introduction of LiTFSI salt, the Li+-adsorption propensity towards the surface along the anatase (100) step edge plane is evident in both x-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) analysis. Ab initio molecular dynamics (AIMD) analysis corroborates the site-preferential interaction of Li+ cations with oxygen vacancies and the thermodynamically favorable transport through the (100) step edge plane. Using 7Li nuclear magnetic resonance (NMR) chemical shift and relaxometry measurements, the presence of Li+ cations near the interface between TiO2 and the bulk LiTFSI phase was identified, and subsequent diffusion properties were analyzed. The lower activation energy derived from NMR analysis reveals enhanced mobility of Li+ cations along the surface, in good agreement with AIMD calculations. On the other hand, the TFSI– anion interaction with defect sites leads to CF3 bond dissociation and subsequent generation of carbonyl fluoride-type species. The multimodal spectroscopic analysis including NMR, electron paramagnetic resonance (EPR), and x-ray photoelectron spectroscopy (XPS) confirms the decomposition of TFSI– anions near the anatase surface. The reaction mechanism and electronic structure of interfacial constituents were simulated using AIMD calculations. Overall, this work demonstrates the role of defects at the anatase nanoparticle surface on charge transfer and interfacial reaction processes. 相似文献
48.
Alshymaa Abdel-Rahman Gomaa Usama Ramadan Abdelmohsen Markus Krischke Martin J. Mueller Amira Samir Wanas 《Natural product research》2020,34(18):2612-2615
AbstractThe present study evaluates the chemical composition of Zinnia elegans and Gazania rigens based on their metabolomic profiles using liquid chromatography coupled with high-resolution mass spectrometry (LC‐HR-MS), alongside with the anti-infective activities of their ethanol extracts, as well as, different fractions. A significant difference was observed between the LC-MS profiles of the two plants such as, coumarins, sesquiterpene lactones and phenylethanoids which were characteristic for Z. elegans, while amides and phenolic acid derivatives were characteristic for G. rigens. These results highlight the chemical potential of Z. elegans and G. rigens. Furthermore, the ethyl acetate fraction of Z. elegans showed a significant antimalarial activity with IC50 values of 21.03 and 13.72?µg/mL against Plasmodium falciparum D6 and P. falciparum W2, respectively. 相似文献
49.
Hanjiang Dong Zhengping Zhang Man-Ho Lee D. W. Mueller Richard F. Reidy 《Journal of Sol-Gel Science and Technology》2007,41(1):11-17
Sol-gel polymerization of methyltrimethoxysilane (MTMS) in ethanol using a two-step acid/base catalyzed procedure (B2) is
followed by 29Si NMR spectroscopy. Analysis of the structural evolution of the B2 system shows that esterification of monomeric and end
silicon species is rate-limited while that of linear and cyclic species is able to reach pseudoequilibrium in the second basic
step. Condensation reactivity is reduced with increasing network connectivity, however, to a much less degree under B2 conditions
than MTMS polymerization under acidic conditions. Steric effects as well as many other factors are attributed to this trend.
The concentration of cyclic and polycyclic species of the B2 system is nearly 3 times lower compared to the acid-catalyzed
system. The empirical degree of condensation at the gel point is determined to be 0.88. The effects of cyclization and phase
separation on MTMS gelation are discussed for both B2 and acid-catalyzed systems. Based on these results it is believed that
MTMS-based gels form for B2 and not acid-catalyzed conditions due to reduced cyclization, rapid hydrolysis and condensation,
effective use of functional groups, and effective contribution of branched and polycyclic species as crosslinking points to
connect polymeric chains in the B2 system. 相似文献
50.
EDOT‐diketopyrrolopyrrole copolymers for high bulk hole mobility and near infrared absorption 下载免费PDF全文
Christian J. Mueller Chetan R. Singh Mukundan Thelakkat 《Journal of Polymer Science.Polymer Physics》2016,54(6):639-648
To obtain novel low‐bandgap materials with tailored hole‐transport properties and extended absorption, electron rich 3,4‐ethylenedioxythiophene is introduced as a comonomer in diketopyrrolo[3,4‐c]pyrrole copolymers with different aryl flanking units. The polymers are characterized by absorption and photoluminescence spectroscopy, dynamic scanning calorimetry, cyclic voltammetry, and X‐ray diffraction. The charge transport properties of these new materials are studied carefully using an organic field effect transistor geometry where the charge carriers are transported over a narrow channel at the semiconductor/dielectric interface. These results are compared to bulk charge carrier mobilities using space‐charge limited current (SCLC) measurements, in which the charge carrier is transported through the complete film thickness of several hundred nanometers. Finally, charge carrier mobilities are correlated with the electronic structure of the compounds. We find that in particular the thiophene‐flanked copolymer PDPP[T]2‐EDOT is a very promising candidate for organic photovoltaics, showing an absorption response in the near infrared region with an optical bandgap of 1.15 eV and a very high bulk hole mobility of 2.9 × 10?4 cm2 V?1 s?1 as measured by SCLC. This value is two orders of magnitudes higher than SCLC mobilities reported for other polydiketopyrrolopyrroles and is in the range of the well‐known hole transporting polymer poly(3‐hexylthiophene). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 639–648 相似文献