Reinhard Zellner

Bio: Reinhard Zellner is an academic researcher from University of Duisburg-Essen. The author has contributed to research in topics: Reaction rate constant & Radical. The author has an hindex of 35, co-authored 156 publications receiving 4910 citations. Previous affiliations of Reinhard Zellner include University of Göttingen.

Nanoparticle Size Is a Critical Physicochemical Determinant of the Human Blood Plasma Corona: A Comprehensive Quantitative Proteomic Analysis

Abstract: In biological fluids, proteins associate with nanoparticles, leading to a protein “corona” defining the biological identity of the particle. However, a comprehensive knowledge of particle-guided protein fingerprints and their dependence on nanomaterial properties is incomplete. We studied the long-lived (“hard”) blood plasma derived corona on monodispersed amorphous silica nanoparticles differing in size (20, 30, and 100 nm). Employing label-free liquid chromatography mass spectrometry, one- and two-dimensional gel electrophoresis, and immunoblotting the composition of the protein corona was analyzed not only qualitatively but also quantitatively. Detected proteins were bioinformatically classified according to their physicochemical and biological properties. Binding of the 125 identified proteins did not simply reflect their relative abundance in the plasma but revealed an enrichment of specific lipoproteins as well as proteins involved in coagulation and the complement pathway. In contrast, immunoglobul...

CAPRAM2.3: A chemical aqueous phase radical mechanism for tropospheric chemistry

Abstract: A Chemical Aqueous Phase Radical Mechanism (CAPRAM) for modelling tropospheric multiphase chemistry is described. CAPRAM contains (1) a detailed treatment of the oxidation of organic compounds with one and two carbon atoms, (2) an explicit description of S(IV)-oxidation by radicals and iron(III), as well as by peroxides and ozone, (3) the reactions of OH, NO 3 ,C l 2 , Br 2 ,a nd CO 3 radicals, as well as reactions of the transition metal ions (TMI) iron, manganese and copper. A modelling study using a simple box model was performed for three different tropospheric conditions (marine, rural and urban) using CAPRAM coupled to the RADM2-mechanism (Stockwell et al., 1990) for liquid and gas phase chemistry, respectively. In the main calculations the droplets are assumed as monodispersed with a radius of 1m and a liquid water content of 0.3 g m 3 .I n the coupled mechanism the phase transfer of 34 substances is treated by the resistance model of Schwartz (1989). Results are presented for the concentration levels of the radicals in both phases under variation of cloud duration and droplet radius. The effects of the multiphase processes are shown in the loss fluxes of the radicals OH, NO 3 and HO2 into the cloud droplets. From calculations under urban conditions considering gas phase chemistry only the OH maximum concentration level is found to be 5:5 10 6 cm 3 . In the presence of the aqueous phase (r D 1 m, LWC D 0: 3g m 3 ) the phase transfer constitutes the most important sink (58%) reducing the OH level to 1:0 10 6 cm 3 . The significance of the phase transfer during night time is more important for the NO3 radical (90%). Its concentration level in the gas phase (1:9 10 9 cm 3 ) is reduced to 1:4 10 6 cm 3 with liquid water present. In the case of the HO2 radical the phase transfer from the gas phase is nearly the only sink (99.8%). The concentration levels calculated in the absence and presence of the liquid phase again differ by three orders of magnitude, 6 10 8 cm 3 and 4:9 10 5 cm 3 , respectively. Effects of smaller duration of cloud occurrence and of droplet size variation are assessed. Furthermore, in the present study a detailed description of a radical oxidation chain for sulfur is presented. The most important reaction chain is the oxidation of (hydrogen) sulphite by OH and the subsequent conversion of SO 3 to SO 5 followed by the interaction with TMI (notably Fe 2C )a nd chloride to produce sulphate. After 36 h of simulation ((H2O2U0 D 1 ppb; (SO2U0 D 10 ppb) the direct oxidation pathway from sulfur(IV) by H2O2 and ozone contributes only to 8% (2:9 10 10 M s 1 ) of the total loss flux of S(IV) (3 :7 10 9 Ms 1 ).

Absolute OH quantum yields in the laser photolysis of nitrate, nitrite and dissolved H2O2 at 308 and 351 nm in the temperature range 278–353 K

Abstract: Absolute quantum yields for the formation of OH radicals in the laser photolysis of aqueous solutions of NO3 -, NO2 - and H2O2 at 308 and 351 nm and as a function of pH and temperature have been measured. A scavenging technique involving the reaction between OH and SCN- ions and the time resolved detection by visible absorption of the (SCN)2 - radical ion was used to determine the absolute OH yields. The following results were obtained:

The influence of proteins on the dispersability and cell-biological activity of silver nanoparticles

Abstract: Spherical silver nanoparticles with a diameter of 50 ± 20 nm and stabilized with either poly(N-vinylpyrrolidone) (PVP) or citrate were dispersed in different cell culture media: (i) pure RPMI, (ii) RPMI containing up to 10% of bovine serum albumin (BSA), and (iii) RPMI containing up to 10% of fetal calf serum (FCS). The agglomeration behavior of the nanoparticles was studied with dynamic light scattering and optical microscopy of individually tracked single particles. Whereas strong agglomeration was observed in pure RPMI and in the RPMI–BSA mixture within a few hours, the particles remained well dispersed in RPMI–FCS. In addition, the biological effect of PVP-stabilized silver nanoparticles and of silver ions on human mesenchymal stem cells (hMSCs) was studied in pure RPMI and also in RPMI–BSA and RPMI–FCS mixtures, respectively. Both proteins considerably increased the cell viability in the presence of silver ions and as well as silver nanoparticles, indicating a binding of silver by these proteins.

Rate measurements of reactions of OH by resonance absorption. Part 2.—Reactions of OH with CO, C2H4 and C2H2

Abstract: The rates of the reactions of OH with CO, C2H4 and C2H2 have been determined between 210 K and 460 K using time-resolved resonance absorption to monitor the removal of OH radicals following their creation by flash photolysis of mixtures containing H2O or N2O + H2. At 300 K, the rate constant, k6, for OH + CO → CO2+ H (6) is 8.7 × 1010 cm3 mol–1 s–1; k6 shows a slight positive temperature dependence, but the Arrhenius plot appears to be slightly curved. The nature of the path of this reaction is discussed and the results of transition state calculations are shown to agree well with the experimental data and to predict marked curvature in the Arrhenius plot above 500 K. The rate constants, k9 and k10, for the primary reactions of OH with C2H4 and C2H2 also increase only very slowly with temperature but, in these cases, the experimental results for 210 K ⩽T⩽ 460 K do fit Arrhenius expressions (energies of activation in kJ mol–1): k9= 4.5 × 1012 exp[– 0.9/RT] cm3 mol–1 s–1. k10= 1.2 × 1012 exp[– 2.1/RT] cm3 mol–1 s–1.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

The formation, properties and impact of secondary organic aerosol: current and emerging issues

Abstract: Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol and a detailed knowledge of the formation, properties and transformation of SOA is therefore required to evaluate its impact on atmospheric processes, climate and human health. The chemical and physical processes associated with SOA formation are complex and varied, and, despite considerable progress in recent years, a quantitative and predictive understanding of SOA formation does not exist and therefore represents a major research challenge in atmospheric science. This review begins with an update on the current state of knowledge on the global SOA budget and is followed by an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and the analytical techniques used to determine the chemical composition of SOA. A survey of recent laboratory, field and modeling studies is also presented. The following topical and emerging issues are highlighted and discussed in detail: molecular characterization of biogenic SOA constituents, condensed phase reactions and oligomerization, the interaction of atmospheric organic components with sulfuric acid, the chemical and photochemical processing of organics in the atmospheric aqueous phase, aerosol formation from real plant emissions, interaction of atmospheric organic components with water, thermodynamics and mixtures in atmospheric models. Finally, the major challenges ahead in laboratory, field and modeling studies of SOA are discussed and recommendations for future research directions are proposed.

Organic aerosol and global climate modelling: a review

Abstract: The present paper reviews existing knowledge with regard to Organic Aerosol (OA) of importance for global climate modelling and defines critical gaps needed to reduce the involved uncertainties. All pieces required for the representation of OA in a global climate model are sketched out with special attention to Secondary Organic Aerosol (SOA): The emission estimates of primary carbonaceous particles and SOA precursor gases are summarized. The up-to-date understanding of the chemical formation and transformation of condensable organic material is outlined. Knowledge on the hygroscopicity of OA and measurements of optical properties of the organic aerosol constituents are summarized. The mechanisms of interactions of OA with clouds and dry and wet removal processes parameterisations in global models are outlined. This information is synthesized to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosol. The sources of uncertainties at each step of this process are highlighted as areas that require further studies.