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排序方式: 共有760条查询结果,搜索用时 31 毫秒
1.
Dr. Tomasz Ratajczyk Prof. Dr. Gerd Buntkowsky Dr. Torsten Gutmann Dr. Bartłomiej Fedorczyk Dr. Adam Mames Dr. Mariusz Pietrzak Zuzanna Puzio Piotr Grzegorz Szkudlarek 《Chembiochem : a European journal of chemical biology》2021,22(5):855-860
The biorelevant PyFALGEA oligopeptide ligand, which is selective towards the epidermal growth factor receptor (EGFR), has been successfully employed as a substrate in magnetic resonance signal amplification by reversible exchange (SABRE) experiments. It is demonstrated that PyFALGEA and the iridium catalyst IMes form a PyFALGEA:IMes molecular complex. The interaction between PyFALGEA:IMes and H2 results in a ternary SABRE complex. Selective 1D EXSY experiments reveal that this complex is labile, which is an essential condition for successful hyperpolarization by SABRE. Polarization transfer from parahydrogen to PyFALGEA is observed leading to significant enhancement of the 1H NMR signals of PyFALGEA. Different iridium catalysts and peptides are inspected to discuss the influence of their molecular structures on the efficiency of hyperpolarization. It is observed that PyFALGEA oligopeptide hyperpolarization is more efficient when an iridium catalyst with a sterically less demanding NHC ligand system such as IMesBn is employed. Experiments with shorter analogues of PyFALGEA, that is, PyLGEA and PyEA, show that the bulky phenylalanine from the PyFALGEA oligopeptide causes steric hindrance in the SABRE complex, which hampers hyperpolarization with IMes. Finally, a single-scan 1H NMR SABRE experiment of PyFALGEA with IMesBn revealed a unique pattern of NMR lines in the hydride region, which can be treated as a fingerprint of this important oligopeptide. 相似文献
2.
The aim of this study was to investigate the structure and corrosion resistance of amorphous, amorphous‐crystalline, and crystalline Mg67Zn29Ca4 alloy for biodegradable applications. This paper presents a preparation method and results of the structural characterization and corrosion resistance analysis of the material. Samples were prepared in the form of 3 mm diameter rods. The structure of the alloy was examined with the use of X‐ray diffractometry and scanning electron microscopy. The thermal properties of the samples were examined with differential scanning calorimetry (DSC). Results of DSC analysis were used to determine heat treatment temperatures, allowing to obtain different fractures of crystalline phase in the material. Corrosion resistance of heat‐treated samples was investigated by immersion tests and electrochemical measurements performed in the simulated body fluid. The X‐ray diffraction results confirmed that the prepared Mg67Zn29Ca4 alloy's structure is fully amorphous. After heat treatment, samples with different fractions of amorphous phase in the structure were obtained. Immersion tests of the samples showed that the structure significantly influenced corrosion resistance in examined materials. It should be pointed out, that certain amounts of crystalline phase in amorphous matrix can greatly improve the corrosion resistance of Mg67Zn29Ca4 alloy. 相似文献
3.
4.
Analysis of non-stationary electrochemical oscillations emerges utilization of the techniques allowing an observation of time evolution of their parameters such as instantaneous frequency, amplitude or frequency band. An algorithm of extraction of these parameters can be based on one of linear or quadratic time-frequency representations of oscillations record. In this paper, the authors present representatives of such transformations (Choi-Williams and Cone-shaped) originating from one of the most popular joint time-frequency energy distribution—Wigner-Ville distribution. Short introduction to the mathematics of the topic discussed is provided, then the authors present an example of application in the analysis of current oscillations of copper dissolution process. 相似文献
5.
High-density structures with relatively well-ordered nanopore arrays have been obtained by the self-ordering growth of nanopores occurring during anodisation of aluminium in sulphuric acid. The resulting array of well-ordered nanopores strongly depends on an applied voltage of anodising, temperature and a procedure of synthesis. Regular arranged hexagonal arrays on aluminium with a relatively uniform pore diameter, interpore distance, and depth of pores exceeding 90 μm, can be formed by the self-ordering two-step anodising at 1 °C. The interpore distance and the pore diameter were evaluated on anodised aluminium layers obtained at different cell potentials ranging from 15 to 25 V. The detailed analyses of their uniformity were performed from SEM images. The analysis of a pore arrangement defects was made from SEM top view images taken on samples anodised at various cell potentials. The defect maps, known as Delaunay triangulations, of the arrangement of about 1000 pores were constructed for different applied anodising potentials. The percentage of pores that are not six-fold coordinated by the neighbouring pores indicates the percentage of defected surface. 相似文献
6.
We describe a formal language/notation for DNA molecules that may contain nicks and gaps. The elements of the language, DNA
expressions, denote formal DNA molecules. Different DNA expressions may denote the same formal DNA molecule. We analyse the
shortest DNA expressions denoting a given formal DNA molecule. We determine lower bounds on their lengths and explain how
we construct these minimal DNA expressions. 相似文献
7.
The cognitive exhaustion model of helplessness (predicting withdrawal from constructive effortful processing after uncontrollability) was applied to decision making. After unsolvable problems (or no preexposure), Ss requested information from a matrix with 5 alternatives (films)?×?10 attributes and then chose the best film. Films in a set were either similar (difficult decision) or dissimilar (easy decision) in attractiveness. As predicted, Ss with an uncontrollable preexposure spent less time on predecisional information search, disregarded their own importance criteria when asking for information, and had attention highly focused on a selected option for the easy decision condition but diffused across options for the difficult decision condition. The implications of these findings for understanding cognitive mechanisms of learned helplessness and depression are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
Anna Michalska Alicja Ceglińska Henryk Zieliński 《European Food Research and Technology》2007,225(3-4):545-551
Rye flours with extraction rate of 100% (wholemeal flour), 95% (brown flour), 90% (brown flour) and 70% (light flour) were
prepared in order to study the relation between flour extraction rates and content of bioactive compounds. The following compounds
were analysed: total phenolic compounds (TPC), total flavonoids (TF), inositol hexaphosphate (IP6), reduced (GSH) and oxidized
(GSSG) glutathione, tocopherols (T) and tocotrienols (T3). The reduced/oxidized glutathione status (GSH/GSSG) of the flours
was examined as a potential index of flour resistance against oxidative stress. The following observations were made in relation
to the flour extraction rates and bioactive compounds contents: (a) milling process caused decrease in content in TPC, TF,
IP6, GSH and GSSG, T and T3, (b) the most resistant against oxidation processes were suggested a brown flours, then light
and finally wholemeal flour, (c) the ratio of tocotrienols to tocopherols (T3/T) was the highest in rye flours with extraction
rate of 100–90% whereas light flour was the poorest source of tocopherols and tocotrienols. The provided data support current
trend to increase number of rye products from wholemeal or brown flours. 相似文献
9.
A grid (or a mesh) is a two-dimensional permutation: an m× n-grid of size mn is an m× n-matrix where the entries run through the elements {1,2, …, mn}. We prove that if δ1 and δ2 are any two linear orders on {1,2, …, N}, then they can be simultaneously embedded (in a well defined sense) into a unique grid having the smallest size. 相似文献
10.
Post-lesion acquisition of two-way avoidance and subsequent transfer to two warning signals (conditioned stimulus, CS) of different modality were investigated in 60 rats. In Experiment I the animals were originally trained with less salient (darkness) CS, then transferred to more salient compound (darkness and white noise), and finally to white noise CS. The opposite arrangement of the conditioned stimuli (CSi) during the subsequent stages was employed in Experiment II. In control animals, avoidance acquisition was faster and the intertrial responding (ITR) rate lower with the auditory than with the visual CS. Lesioned rats learned avoidance responses more slowly, independently of CS modality. The transfer to other CSi revealed dramatic between-group difference in the level and consistency of avoidance response, shuttle-box latencies and ITR rate. In control animals, transfer to more salient CSi enhanced avoidance performance, whereas change to less salient CS decreased it. Rather small changes in shuttle-box performance and consistency of avoidance response due to CS modality were seen in rats with the basolateral lesions. In contrast, central nucleus injury caused a strong deterioration in the avoidance transfer, especially when the visual CS followed the acoustic one. The results indicate differential involvement of the basolateral and central amygdala nuclei in stimulus-processing mechanisms of instrumental defensive behavior. 相似文献