Zobrazení zdroje stránky Steeledahlgaard6932

The fact that there is no pinocembrin or pinocembrin-derived flavonoid accumulated in E. wushanense prompted us to propose that pinocembrin is likely converted into naringenin in vivo, constituting two parallel biosynthetic pathways for naringenin. Therefore, our study provides a basis for the full elucidation of the biosynthetic logic of prenyl-flavonoid glycoside in Epimedium, paving the way for future metabolite engineering and molecular breeding of E. wushanense to acquire a higher titre of desired, bioactive flavonoid compounds.A highly efficient pretreatment strategy using ethylene glycol with dilute sulfuric acid was developed for the fractionation of lignocellulose. The pretreatment behaviors were related to the composition analysis and structure of the samples analyzed by SEM, XRD, FTIR and 2D HSQC NMR, resulting in 80.3% delignification and 84.7% retention of cellulose under the selected conditions (120 °C, 60 min, and 0.6 wt% H2SO4 (w/w)). The enzymatic hydrolysis sugar yield significantly increased from 24.1 to 70.6% (3 FPU g-1), which displayed immense improvement compared with untreated corn stover (24.1%), nearly 3-fold higher than its untreated counterparts. Besides, the regenerated lignin could be fitted to valorize renewable aromatic chemicals and alkane fuels. The present study shows that the pretreatment is a simple, efficient and promising process for corn stover biorefinery.Tyrosinase, widely distributed in nature, is a copper-containing polyphenol oxidase involved in the formation of melanin. Flavonoids are most often considered as tyrosinase inhibitors but have also been confirmed to be tyrosinase substrates. Four structure-related flavonoids including flavones (apigenin and luteolin) and flavonols (kaempferol and quercetin) are found to promote not inhibit browning induced by tyrosinase catalyzed oxidation both in model systems and in mushrooms under aerobic conditions. A comparison with enzymatic oxidation and autooxidation of flavonoids alone has helped to clarify why flavonoids function as a substrate rather than an inhibitor. Flavonoids almost do not affect the kinetics of melanin formation from enzymatic oxidation of l-dopa in excess. In addition, a new brown complex formed during the reaction of flavonoid quinone and dopaquinone is suggested to enhance the browning effects by competing with isomerization and autooxidation. [https://www.selleckchem.com/products/onx-0914-pr-957.html check details] Structure-activity relationships of the four flavonoids in melanin formation leading to browning induced by autooxidation and enzymatic oxidation confirm the enzymatic nature of the browning.Divergent and versatile synthetic routes to flavones and flavanones via efficient Pd(ii) catalysis are disclosed. These Pd(ii) catalyses expediently provide a variety of flavones and flavanones from 2'-hydroxydihydrochalcones as common intermediates, depending on oxidants and additives, via discriminate oxidative cyclization sequences involving dehydrogenation, respectively, in a highly atom-economic manner.This work reported two monolithic conjugated microporous polymer (CMP) foams synthesized through the Sonogashira-Hagihara cross-coupling reaction without mechanical stirring. The as-synthesized (CMP-ED and CMP-PT) foams exhibited superior hydrophobicity and low apparent density of 58 mg cm-3 and 63 mg cm-3. In addition, CMP-ED displayed a low thermal conductivity of 34.04 mW m-1 K-1, which was comparable with commercial SiO2 aerogels (34.09 mW m-1 K-1) at 50% humidity conditions. When the environment humidity was raised from 50% to 70%, the thermal conductivity of CMP-ED and commercial SiO2 aerogels improved by 0.12% and 7%, respectively. Furthermore, XRD, FTIR, BET and TG were conducted to evaluate the bulk structure and stability of CMP-ED and CMP-PT. The results illustrated the thermal conductivity values were greatly affected by the pore structure of foams. And the strong hydrophobicity and the narrow pore structure were responsible for the good thermal insulation performance under humid conditions. Considering the low density, superhydrophobicity, excellent physicochemical stability and impervious thermal conductivity in a high humidity environment, this CMP-ED presented great potential as an insulating material in a humid environment.The mechanical properties of cancer cells at the single-cell and the subcellular level might be the key for answering long-standing questions in the diagnosis and treatment of cancer. However, the subcellular distribution of two main mechanical properties, cell stiffness and traction forces, has been investigated only rarely and qualitatively yet. Here, we present the first direct combination of scanning ion conductance microscopy (SICM) and traction force microscopy (TFM), which we used to identify a correlation between the local stiffness and the local traction force density in living cells. We found a correlation in normal breast epithelial cells, but no correlation in cancerous breast epithelial cells. This indicates that the interplay between cell stiffness and traction forces is altered in cancer cells as compared to healthy cells, which might give new insight in the research field of cancer cell mechanobiology.Mg-Li based alloys have been widely used in various fields. However, the widespread use of Mg-Li based alloys were restricted by their poor properties. The addition of rare earth element in Mg-Li can significantly improve the properties of alloys. In the present work, different electrochemical methods were used to investigate the electrochemical behavior of Y(iii) on the W electrode in LiCl-KCl melts and LiCl-KCl-MgCl2 melts. In LiCl-KCl melts, typical cyclic voltammetry was used to study the electrochemical mechanism and thermodynamic parameters for the reduction of Y(iii) to metallic Y. In LiCl-KCl-MgCl2 melts, the formation mechanism of Mg-Y intermetallic compounds was investigated, and the results showed that only one kind of Mg-Y intermetallic compound was formed under our experimental conditions. Mg-Li-Y alloys were prepared via galvanostatic electrolysis, and XRD and SEM equipped with EDS analysis were used to analyze the samples. Because of the restrictions of EDS analysis, ICP-AES was used to analyze the Li content in Mg-Li-Y alloys. The microhardness and Young's modulus of the Mg-Li-Y alloys were then evaluated.SAPO-18 and SAPO-35 were synthesized and utilized as the zeotype in the bifunctional catalyst for the STO process, respectively. SEM and Ar physisorption proved that SAPO-18 displayed abundant outer cages, and facilitated the diffusion of the reactant and products. NH3-TPD revealed the adequate acid strength of SAPO-18, thus ZnCrO x + SAPO-18 bifunctional catalyst showed high selectivity to light olefins during the whole stage of the STO process. 19.9% CO conversion and 68.6% light olefins selectivity (free of CO2) was achieved over ZnCrO x + SAPO-18(0.048) at 653 K, 1.0 MPa, GHSV = 6000 mL g-1 h-1. The catalytic performance was stable after 6000 minutes of reaction because of the good diffusibility of SAPO-18. GC-MS and TG demonstrated that the ZnCrO x + SAPO-35 bifunctional catalyst deactivated very quickly because of the severe formation of the heavy coke deposits, which should be attributed to the acidic properties of SAPO-35 and the poor diffusibility originating from its 2-dimensional channel system. Although the ZnCrO x + SAPO-35 bifunctional catalyst exhibited high CO conversion and light olefins selectivity at the early stage of the STO process as well, its catalytic performance was unsustainable.Crystal structure and properties of Sr11Mo4O23 treated at 1100 and 1400 °C were studied via synchrotron X-ray powder diffraction and thermogravimetric analysis, coupled with mass spectrometry. Synchrotron studies reveal the crystallographic effect of the annealing temperature, showing that the lowest-temperature phase must be defined in a triclinic symmetry, in contrast to the cubic one obtained at 1400 °C. The mass spectrometry allowed the identification of the released compounds during the thermogravimetric analysis, thus unveiling the physicochemical behavior of the sample during the heating process. Furthermore, an aging analysis was made, confirming the superior stability of this sample when it is treated at 1400 °C. Finally, an optimized sintering procedure allowed us to obtain a superior density and hence the highest conductivity measured so far for this system.An efficient, cost-effective, transition-metal-free, oxidative C(sp2)-H/C(sp2)-H cross-dehydrogenative coupling via a C(sp2)-H bond functionalization protocol for the regioselective direct C-3 acylation/benzoylation of substituted 2H-Indazoles 1a-m with substituted aldehydes 2a-q/benzyl alcohols 5a-e/styrenes 6a-e is reported. The operationally simple protocol proceeds in the presence of tert-butyl peroxybenzoate (TBPB) as an oxidant in chlorobenzene (PhCl) as a solvent at 110 °C for 24 h under an inert atmosphere, which furnished a diverse variety of substituted 3-(acyl/benzoyl)-2H-indazoles 3a-q/4a-l in up to 87% yields. The reaction involves a free-radical mechanism and proceeds via the addition of an in situ generated acyl radical (from aldehydes/benzyl alcohols/styrenes) on 2H-indazoles. The functional group tolerance, broad substrate scope, control/competitive experiments and gram-scale synthesis and its application to the synthesis of anti-inflammatory agent 11 and novel indazole-fused diazepine 13 further signify the versatile nature of the developed methodology.A new strategy was developed to produce cellulose nanofibrils (CNFs) and films from raw elephant grass using deep eutectic solvents and a recyclable spent coffee-derived solid acid (SC-SO3H) catalyst with assistance of ultrasonic disintegration and a suction filtration film forming method. The effects of a solid acid and reused solid acid were comprehensively studied by comparing with catalyst-free conditions and using sulfuric acid as the catalyst. The CNF fibers obtained from this novel SC-SO3H catalyst method showed the longest fiber length. The corresponding films achieved the strongest tensile strength of 79.8 MPa and the elongation at break of 13.6%, and best thermostability. In addition, the performance of CNFs and films prepared by the fourth recovered SC-SO3H-4 catalyst was close to that obtained with the first use. The SC-SO3H could be reused by a simple decantation method, meaning this novel method has the potential for green and sustainable preparation of CNFs and films.Three alginates with fundamentally different block structures, poly-M, poly-G, and poly-MG, have been investigated upon ionic crosslinking with chitosan oligosaccharides (CHOS), using circular dichroism (CD), rheology, and computer simulations, supporting the previously proposed gelling principle of poly-M forming zipper-like junction zones with chitosan (match in charge distance along the two polyelectrolytes) and revealing a unique high gel strength poly-MG chitosan gelling system. CD spectroscopy revealed an increased chiroptical activity exclusively for the poly-M chitosan gelling system, indicative of induced conformational changes and higher ordered structures. Rheological measurement revealed gel strengths (G' less then 900 Pa) for poly-MG (1%) CHOS (0.3%) hydrogels, magnitudes of order greater than displayed by its poly-M analogue. Furthermore, the ionically crosslinked poly-MG chitosan hydrogel increased in gel strength upon the addition of salt (G' less then 1600 at 50 mM NaCl), suggesting a stabilization of the junction zones through hydrophobic interactions and/or a phase separation.