Rh-based catalysts have attracted much attention due to their ability to efficiently break c-c bonds in ethanol oxidation reaction(EOR), while pure Rh catalyst have low EOR activity. It is important to improve the EOR...
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Rh-based catalysts have attracted much attention due to their ability to efficiently break c-c bonds in ethanol oxidation reaction(EOR), while pure Rh catalyst have low EOR activity. It is important to improve the EOR activity of Rh-based catalyst. Herein, we have been successfully synthesized carbon supported Rh, Rh-Pb, and Rh-Ru alloy catalysts. The catalytic activity of RhPb/c for ethanol oxidation is 0.96 mA/cm2, which is 8 times than that of Rh/c. The steady-state current density of RhPb/c at 0.5 V is 17 and 20 times higher than that of RhRu/c and Rh/c, respectively. The results show that adding a small portion of lead significantly enhanced the Rh-based catalyst activity, stability, and anti-poisoning ability during EOR in alkaline media. Moreover, the Tafel slope of RhPb/ccatalyst for EOR is 118 mVdec-1, which is similar with that of Pt/c (116 mVdec-1), while the Tafel slope of RhRu/c is 77 mVdec-1, similar to that of Rh/c(87 mVdec-1). The cO-stripping potential of RhRu/c, Rh/c and RhPb/c is 0.535 V, 0.573 V and 0.601 V, respectively. combined with the cyclic voltammetry, chronoamperometry, cO-stripping and Tafel analysis, it is concluded that for RhRu/ccatalyst, the improvement of EOR is mainly attributed to the bifunctional mechanism, while for RhPb/ccatalyst, the ensemble effect and the electronic effect of Pb is essential to the improvement of EOR.
An efficient method for catalyzing the ammoxidation of aromatic alcohols to aromatic nitriles was developed, in which a new heterogeneous catalyst based on transition metal elements was employed, the new catalyst was ...
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An efficient method for catalyzing the ammoxidation of aromatic alcohols to aromatic nitriles was developed, in which a new heterogeneous catalyst based on transition metal elements was employed, the new catalyst was named co-[Bmim]Br/c-700 and then characterized by X-ray photo-electronic spectroscopy, transmission electron microscope and X-ray diffraction. The reaction was carried out by two consecutive dehydrogenations under the catalysis of co-[Bmim]Br/c-700, which catalytically oxidized the alcohol to the aldehyde, and then the aldehyde was subjected to ammoxidation to the nitrile. The catalyst system was suitable for a wide range of substrates and nitriles obtained in high yields, especially, the conversion rate of benzyl alcohol, 4-methoxybenzyl alcohol, 4-chlorobenzyl alcohol and 4-nitrobenzyl alcohol reached 100%. The substitution of ammonia and oxygen for toxiccyanide to participate in the reaction accords with the theory of green chemistry.
The influence of nitrate (NO3- -N) concentrations (40, 80 mg/L marked as R40 and R80) and carbon/nitrogen (c/N) ratios (0.8,1.5, 2.5, 3.5, 4.5) on nitrite (NO2- -N) accumulation in partial denitrification (PD) process...
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The influence of nitrate (NO3- -N) concentrations (40, 80 mg/L marked as R40 and R80) and carbon/nitrogen (c/N) ratios (0.8,1.5, 2.5, 3.5, 4.5) on nitrite (NO2- -N) accumulation in partial denitrification (PD) process was investigated. The results proved that R40-3.5 and R80-2.5 systems showed the optimal NO2- -N contents and nitrate-tonitrite transformation ratio (NTR) values of 14.88, 29.77 mg/L and 52.87 %, 59.12 % with strong resistance to low temperature (12.5-3.8 degrees c). Batch tests displayed the NO2- -N accumulation mechanism via substrate transformations, and the metabolic pathways of nitrogen and carbon for PD and complete denitrification were also compared. Based on the Monod equation, the half-saturation constants of 58.33 and 61.20 mg/L were estimated with zero-order reaction for NO3- -N and NO2- -N reduction, showing a tighter affinity to NO3- -N concentration. Proteobacteria, Bacteroidota, Acidobacteriota and chloroflexi were the four dominant phyla with total percentages of 85.16-94.55 % and 90.81-96.85 % in R40 and R80 groups, while Thauera, Flavobacterium contributing to NO2- N accumulation reached up to 42.79 % and 52.13 % in the R40-3.5 and R80-2.5 systems. The above discussion demonstrated that lower c/N ratio and higher NO3- -N concentration were more favorable for the PD formation.
Two-dimensional (2D) Ti3c2Tx MXene has important potential applications in supercapacitor due to its high electrical conductivity, good hydrophilicity and abundant surface functional groups. It can be prepared into fi...
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Two-dimensional (2D) Ti3c2Tx MXene has important potential applications in supercapacitor due to its high electrical conductivity, good hydrophilicity and abundant surface functional groups. It can be prepared into films of flexible electrochemical capacitors without adhesives. However, the self-stacking of Ti3c2Tx nanosheets seriously reduces their capacitance. Here, we developed a novel structure of the flexible material c/MoS2@Ti3c2Tx through facile physical mixing, three-dimensional c/MoS2 nanoflowers were successfully inserted between two-dimensional Ti3c2Tx layers. The self-stacking of MoS2 and Ti3c2Tx attenuates simultaneously. And these two materials form a particle-layer structure. At a current density of 0.5 A/g, the freestanding c/ MoS2@Ti3c2Tx film has an excellent specificcapacitance of 410 F g-1, which is 2.6 times that of c/MoS2 and 1.9 times that of Ti3c2Tx, respectively. It remains in good condition after 5000 cycles at 10 A/g, demonstrating excellent long-life cycle stability. The improvement of electrochemical performance is attributed to the particlelayer structure, which effectively avoids the re-packing of Ti3c2Tx and greatly reduces the diffusion distance of electrolyte ions. Furthermore, the addition of c/MoS2 nanoflowers has no effect on the bending ability of MXene composite films. And The nano-flower-like structure of c/MoS2 provides high electric double layer capacitance performance. This study provides new ideas for Ti3c2Tx-based films in the field of energy storage and wearable devices.
MxOy-Na2SO4 (with M = Ni, cr, Fe, Al, Ti, Nb) and NiSO4-Na2SO4 mixtures were prepared and their reactivity was examined at 650 degrees c in air + SO2 (400 and 1000 ppm). The formation of a molten phase for NiSO4-Na2SO...
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MxOy-Na2SO4 (with M = Ni, cr, Fe, Al, Ti, Nb) and NiSO4-Na2SO4 mixtures were prepared and their reactivity was examined at 650 degrees c in air + SO2 (400 and 1000 ppm). The formation of a molten phase for NiSO4-Na2SO4 mixtures and the rapid sulfation of NiO in these conditions were demonstrated. NiO sulfation should be considered when explaining the Type II hot corrosion attacks. cr2O3, Fe2O3 and Al2O3 also react with the gas phase showing these oxides dissolved according to an acidic-fluxing mechanism in air + SO2/SO3 (400 and 1000 ppm) environments. Al2O3 is more soluble than cr2O3 in these conditions.
Selective functionalization of highly inert and ubiquitous c-H bonds that would provide a ready access to synthetically valuable motifs has perplexed the chemists since long. Also, environmental benignity and economic...
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Selective functionalization of highly inert and ubiquitous c-H bonds that would provide a ready access to synthetically valuable motifs has perplexed the chemists since long. Also, environmental benignity and economic viability have been the prime factors driving tremendous interest in c-H functionalization. This has led to many inspiring discoveries infuriating the development of potent catalytic systems that enable the facile replacement of the c-H bonds with conventional functional groups, allowing the construction of c-c, c-N, c-O, c-S, c-B and c -halogen bonds at both sp2 as well as sp3 centres. In fact, catalyticc-H functionalization strategies integrating the benefits of magnetic recovery have emerged as sustainable gateway for affording a diverse array of trans-formations. This review sheds light on the remarkable advancements witnessed in this area as a consequence of integrating the inherent magnetism of catalysts with the cutting-edge direct c-H functionalization strategy. Also, the promising future perspectives comprehensively covered in this review is anticipated to motivate the academic and industrial researchers, arousing their creativity for designing competent sustainable strategies to generate a plethora of pharmaceutically active molecules.
Pd/c embedded polystyrene fibers were successfully prepared by electrospinning. The polystyrene molecules were then cross-linked by paraformaldehyde in sulfuric acid to improve the solvent resistance of composite fibe...
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Pd/c embedded polystyrene fibers were successfully prepared by electrospinning. The polystyrene molecules were then cross-linked by paraformaldehyde in sulfuric acid to improve the solvent resistance of composite fibers. SEM images conformed the preparation of uniform and smooth composite fibers. FT-IR spectra demonstrated that the polystyrene molecules inside fibers have been sulphonated and crosslinked. Heck reactions were used to evaluate the catalytic performance of these novel composite fibers. The catalysis results show that this composite fiber mat catalyzed Heck reactions could be evidently promoted by using preferred reducing alcohol agent and solvent. Under the optimized reaction conditions, this composite fiber mat could effectively catalyze the Heck reactions of aromatic iodides with n-butyl acrylate to afford the products with satisfied yields. Especially, compared with the particulate Pd/ccatalyst, the separation and recycling of this fibrous catalyst from the reaction mixture were significantly improved due to the larger fibrous structure. At last, this fiber catalyst was successfully reused for eight times with little loss of initial catalytic activity, which was even better than the pristine Pd/ccatalyst. Hence, embedment of particulate supported metal catalysts inside the crosslinked polystyrene fibers can effectively improve their catalytic performance and handiness.
Manganese (Mn), even though an essential trace element, causes neurotoxicity in excess. In adults, overexposure to Mn causes clinical manifestations, including dystonia, progressive bradykinesia, disturbance of gait, ...
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Manganese (Mn), even though an essential trace element, causes neurotoxicity in excess. In adults, overexposure to Mn causes clinical manifestations, including dystonia, progressive bradykinesia, disturbance of gait, slurring, and stuttering of speech. These symptoms are mainly because of Mn-associated oxidative stress and degeneration of dopamine neurons in the central nervous system. children with excessive Mn exposure often show learning disabilities but rarely show symptoms associated with dopaminergic neuron dysfunction. It is unclear why Mn exposure shows distinctive clinical outcomes in developing brains versus adult brains. Studies on nematode c. elegans have demonstrated that it is an excellent model to elucidate Mn-associated toxicity in the nervous system. In this study, we chronically exposed Mn to L1 larval stage of the worms to understand the effects on dopamine neurons and cognitive development. The worms showed modified behavior to exogenous dopamine compared to the control. The dopamine neurons showed resistance to neurodegeneration on repeated Mn exposure during the adult stage. As observed in mammalian systems, these worms showed significantly low olfactory adaptive learning and memory. This study shows that c. elegans alters adaptive developmental plasticity during Mn overexposure, modifying its sensitivity towards the metal ion and leads to remodeling in its innate learning behavior. (c) 2021 Published by Elsevier Inc.
In all eukaryoticcells, the most abundant modification of ribosomal RNA (rRNA) is methylation at the ribose moiety (2MODIFIER LETTER PRIME-O-methylation). Ribose methylation at specific rRNA sites is guided by small ...
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In all eukaryoticcells, the most abundant modification of ribosomal RNA (rRNA) is methylation at the ribose moiety (2MODIFIER LETTER PRIME-O-methylation). Ribose methylation at specific rRNA sites is guided by small nucleolar RNAs (snoRNAs) of c/D-box type (c/D snoRNA) and achieved by the methyltransferase Fibrillarin (FIB). Here we used the Illumina-based RiboMethSeq approach for mapping rRNA 2MODIFIER LETTER PRIME-O-methylation sites in A. thaliana col-0 (WT) plants. This analysis detected novel c/D snoRNA-guided rRNA 2MODIFIER LETTER PRIME-O-methylation positions and also some orphan sites without a matching c/D snoRNA. Furthermore, immunoprecipitation of Arabidopsis FIB2 identified and demonstrated expression of c/D snoRNAs corresponding to majority of mapped rRNA sites. On the other hand, we show that disruption of Arabidopsis Nucleolin 1 gene (NUc1), encoding a major nucleolar protein, decreases 2MODIFIER LETTER PRIME-O-methylation at specific rRNA sites suggesting functional/structural interconnections of 2MODIFIER LETTER PRIME-O-methylation with nucleolus organization and plant development. Finally, based on our findings and existent database sets, we introduce a new nomenclature system for c/D snoRNA in Arabidopsis plants.
作者：
Pessoa, JoaoUniv Lisbon
Fac Med Inst Med Mol Joao Lobo Antunes Lisbon Portugal Univ Coimbra
CNC Ctr Neurosci & Cell Biol CIBB Ctr Innovat Biomed & Biotechnol Coimbra Portugal
Apoptosis dysfunction is associated with several malignancies, including cancer and autoimmune diseases. Apoptosis restoration could be an attractive therapeutic approach to those diseases. Mitochondrial outer membran...
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Apoptosis dysfunction is associated with several malignancies, including cancer and autoimmune diseases. Apoptosis restoration could be an attractive therapeutic approach to those diseases. Mitochondrial outer membrane permeabilization is regarded as the point of no return in the 'classical' apoptosis triggering pathway. cytoplasmic release of cytochrome c (cyt c), a mitochondrial electron transporter, is a prominent indicator of such critical step. Therefore, visualizing cyt c efflux in living cells is a convenient approach to address apoptosis triggering and monitor performance of apoptosis restoration strategies. Recent years have been prolific in the development of biosensors to visualize cyt c mitochondrial efflux in living cells, by fluorescence microscopy. These biosensors specifically detect endogenous, untagged cyt c, while showing efficient cellular uptake and reduced cell toxicity. A common aspect is their fluorescence quenching in the absence or presence of bound cyt c, resulting in two main biosensor types: 'turn ON' and 'turn OFF'. In some of these systems, fluorescence intensity of fluorophore-bound aptamers is enhanced upon cyt c binding. In others, cyt c binding to quantum dots quenches their fluorescence. In the present minireview, I describe these biosensors and briefly introduce some hypotheses that could be addressed using these novel tools.
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