基于芯片的直接进样质谱法和气相色谱-质谱测定莱茵衣藻中的极性脂类

目前微藻的脂类分析主要侧重于脂肪酸酯、甘油三酯以及细胞内总脂的分析, 忽视了极性脂类的分析. 本研究建立了一个基于芯片的全自动电喷雾进样系统联用线性离子阱质谱的技术, 用于分析莱茵衣藻中的极性脂类. 通过数据库Lipidblast鉴定出了35种不同种类的极性脂类, 并首次鉴定出20种甜菜碱脂类. 同时利用了GC/TOF-MS来检测莱茵衣藻中的游离脂肪酸, 发现亚油酸、亚麻酸和棕榈酸是莱茵衣藻中含量最丰富的三种脂肪酸. 建立的脂类分析方法为微藻脂类种类全面综合的分析提供了方法上的参考.     

Spinor Relativity

Spinor relativity is a unified field theory, which derives gravitational and electromagnetic fields as well as a spinor field from the geometry of an eight-dimensional complex and ‘chiral’ manifold. The structure of the theory is analogous to that of general relativity: it is based on a metric with invariance group GL(ℂ²), which combines the Lorentz group with electromagnetic U(1), and the dynamics is determined by an action, which is an integral of a curvature scalar and does not contain coupling constants. The theory is related to physics on spacetime by the assumption of a symmetry-breaking ground state such that a four-dimensional submanifold with classical properties arises. In the vicinity of the ground state, the scale of which is of Planck order, the equation system of spinor relativity reduces to the usual Einstein and Maxwell equations describing gravitational and electromagnetic fields coupled to a Dirac spinor field, which satisfies a non-linear equation; an additional equation relates the electromagnetic field to the polarization of the ground state condensate.     

On the maximal volume of convex bodies with few vertices

The problem of determining the largest volume of a (d + 2)-point set in E^d of unit diameter is settled. The extremal polytopes are described completely.     

A quantum chemical study of racemization pathways in substituted chrysene derivatives

The potential-energy surfaces of 5,11-disubstituted 6,12-dimethoxychrysene and chrysene-6,12-dione derivatives were investigated by means of density functional calculations. We report relative energies of all conformers and an identification of the racemisation pathways of the chiral equilibrium structures. By analysis of homodesmotic reactions we were able to obtain an estimate for the strain energy of the substituted compounds. This strain energy can be used as a means of measuring the steric effects exerted by the substituents.     

Untersuchungen der Struktur von „antiferroelektrischem”(NH4)2H3IO6 mit Kernresonanzmethoden

The orientations and asymmetry parameters of the EFG tensors at the different lattice sites of I¹²⁷ in (NH₄)₂H₃IO₆ have been determined by proton-iodine crossover relaxation at room temperature and at 94°K. Based on these results it was possible to prove the existence of superstructure for the hexagonala- andc-directions and to reduce the number of allowed space groups of the low temperature phase to two: \(R\overline 3 c\) andR32. In both space groups half of the hydrogen bonds remain symmetric and only half of them become asymmetric (ordered) on lowering the temperature through the phase transition, but only inR32 there are antipolar sublattices. The transition entropies calculated for this model of the hydrogen arrangement agree fairly well with the measured value. With the evidence available it is not possible to rule out one of the two space groups.     

Contact-mediated nucleation in melt emulsions investigated by rheo-nuclear magnetic resonance

Increasing the efficiency of disperse phase crystallization is of great interest for melt emulsion production as the fraction of solidified droplets determines product quality and stability. Nucleation events must appear within every single one of the μm-sized droplets for solidification. Therefore, primary crystallization requires high subcooling and is, thus, time and energy consuming. Contact-mediated nucleation is a mechanism for intensifying the crystallization process. It is defined as the successful nucleation of a subcooled liquid droplet induced by contact with an already crystallized droplet. We investigated contact-mediated nucleation under shear flow conditions up to shear rates of 457 s⁻¹ for a quantitative assessment of this mechanism. Rheo-nuclear magnetic resonance was successfully used for the time-resolved determination of the solids fraction of the dispersed phase of melt emulsions upon contact-mediated nucleation events. The measurements were carried out in a dedicated Taylor–Couette cell. The efficiency of contact-mediated nucleation decreased with increasing shear rate, whereas the effective second order kinetic constant increased approximately linearly at small shear rates and showed a linear decrease for shear rates higher than about 200 s⁻¹. These findings are in accordance with coalescence theory. Thus, the nucleation rate is optimal at specific flow conditions. There are limitations for successful inoculation at a low shear rate because of rare contact events and at a high shear rate due to too short contact time.     

Poly(ethylene oxide)–poly(ethylene imine) block copolymers as templates and catalysts for the in situ formation of monodisperse silica nanospheres

Block copolymers based on poly(ethylene oxide) (PEO) and poly(ethylene imine) (PEI) are efficient catalysts/templates for the formation of uniform silica nanoparticles. Addition of tetraethylorthosilicate to a solution of PEO–PEI or PEI–PEO–PEI block copolymers results in the formation of silica particles with a diameter of ca. 30 nm and narrow size distribution. The particles precipitated with the diblock copolymers can be redispersed in water after isolation as individual nanoparticles. Evidently, block copolymers based on PEO and PEI serve as excellent templates for the biomimetic and “soft” synthesis of silica nanoparticles.

Comparative evaluation of extraction methods for simultaneous mass-spectrometric analysis of complex lipids and primary metabolites from human blood plasma

Metabolomic results on human blood plasma largely depend on the sample preparation protocols employed for protein precipitation and metabolite extraction. Five different extraction methods were examined, which can be grouped into two categories, liquid-liquid extraction and protein precipitation methods, including long-standing protocols such as the Folch extraction and Bligh-Dyer extraction in comparison to modern methods such as the Matyash protocol and two global metabolite extraction methods. Extracts were subjected to analysis of blood plasma lipids and primary metabolites by using chip-based direct infusion nanoelectrospray tandem mass spectrometry and gas chromatography coupled to time-of-flight mass spectrometry, respectively. Optimal extraction schemes were evaluated based on the number of identified metabolites, extraction efficiency, compound diversity, reproducibility, and convenience for high-throughput sample preparations. Results showed that Folch and Matyash methods were equally valid and robust for lipidomic assessments while primary metabolites were better assessed by the protein precipitation methods with organic solvent mixtures. Graphical Abstract

Schematic workflow of five extraction methods and subsequent mass spectrometry analysis using GC-TOF MS and nanoelectrospray direct-infusion ion trap MS/MS?