Influence of acid–base properties of cobalt–molybdenum catalysts supported on magnesium orthophosphates in isomerization of 3,3-dimethylbut-1-ene

Synthesis and physico-chemical characterization of a pure magnesium phosphate (MgP) prepared by coprecipitation, and MgP modified by introduction of cobalt–molybdenum (4–12 wt.% of MoO₃ with the Co/Mo ratio fixed at 0.5) have been carried out. The structural properties of these catalysts were characterized by X-ray diffraction, their textural properties were determined by N₂ adsorption–desorption isotherms and the dispersion of cobalt–molybdenum was studied by XPS spectroscopy. Their acid properties have been investigated by in situ FT-IR spectroscopy of adsorbed molecules, often, 2,6-dimethylpyridine (pK_a = 6.7), pyridine (pK_a = 5.3). Co–Mo incorporation leads to a modification in the MgP acid–base properties, especially on the acid sites type and number. Thus, lower loading of cobalt–molybdenum species decreased the number of strong Lewis acid sites whereas higher loading increased it. It was found that Lewis acid sites on magnesium phosphates play an important role in the isomerization of 3,3-dimethylbut-1-ene.The 3,3-dimethylbut-1-ene (33DMB1) conversion increases with the reaction temperature from 493 to 653 K for MgP, but decreases after 573 K for MgP supported by Co–Mo. A linear relationship between both types of acid sites and conversion values was found. The deactivation of the catalysts appears at high reaction temperature (>573 K).     

小型二氧化钛团簇(TiO2)n (n=2-8)的低能异构体研究

钛和氧之间存在多种成键方式,但迄今为止,二氧化钛团簇均只有少数几种异构体被报道. 与广泛使用的全局优化方法不同,本工作通过优化大量的随机初始结构,获得(TiO₂)_n (n=2-8)团簇稳定异构体. 首先利用PM6半经验方法对高达一万个以上的初始结构进行初步的优化筛选,并对筛选出的结构进行进一步的DFT计算以获得二氧化钛团簇的稳定异构体. 利用这种策略,发现了大量未经报道的稳定异构体,并提出了(TiO₂)₅和(TiO₂)₈新的最稳定异构体. 这些结构中包括含3个末端氧原子的异构体、含5配位氧原子和6配位钛原子的异构体等未经报道的新结构类型. 与丰富成键特征相对应,发现异构体数目随团簇尺寸的增大而急剧增加,对于(TiO₂)₇和(TiO₂)₈,能量在30 kcal/mol以内的异构体都在50个以上. 该工作发现了大量的二氧化钛小型团簇异构体,并凸显了其多样的结构特征,增进了对二氧化钛纳米团簇的结构、成键的理解,并为进一步的理论模拟、力场优化等提供了理论基础.     

Best proximity point theorems: exposition of a significant non-linear programming problem

The primary goal of this work is to address the non-linear programming problem of globally minimizing the real valued function x → d(x, Tx) where T is presumed to be a non-self mapping that is a generalized proximal contraction in the setting of a metric space. Indeed, an iterative algorithm is presented to determine a solution of the preceding non-linear programming problem that focuses on global optimization. As a sequel, one can compute optimal approximate solutions to some fixed point equations and optimal solutions to some unconstrained non-linear programming problems.     

Study of Cylindrical Polytropes with Cosmological Constant

Journal of Experimental and Theoretical Physics - In this paper, we study cylindrically symmetric perfect fluid distribution in the presence of cosmological constant satisfying two cases of...     

Continuous Flow Synthesis of a Zr Magnetic Framework Composite for Post-Combustion CO2 Capture

Metal-organic frameworks (MOFs) have an unprecedented ability to store gas molecules, however energy efficient regeneration remains challenging. Use of magnetic induction to aid this shows promise, but economical synthesis of the requisite composites is unresolved. Continuous flow chemistry has been reported as a rapid and reliable method of MOF synthesis, delivering step-change improvements in space time yields (STY). Here the scalable production of nanomaterials suitable for regeneration by magnetic induction is demonstrated. The zirconium MOF composite, MgFe₂O₄@UiO-66-NH₂ is prepared using continuous flow chemistry resulting in a material of comparable performance to its batch counterpart. Upscaling using flow chemistry gave STY >25 times that of batch synthesis. Magnetic induced regeneration using this mass produced MFC for carbon capture is then demonstrated.     

Estimating error bounds for quaternary subdivision schemes

This paper deals with the error estimation techniques of quaternary subdivision schemes. The estimation is expressed in terms of initial control point sequences and constants. It is independent of subdivision process and parametrization therefore its evaluation is straightforward.     

Postharvest Drying Techniques Regulate Secondary Metabolites and Anti-Neuroinflammatory Activities of Ganoderma lucidum

Ganoderma lucidum extract is a potent traditional remedy for curing various ailments. Drying is the most important postharvest step during the processing of Ganoderma lucidum. The drying process mainly involves heat (36 h at 60 °C) and freeze-drying (36 h at −80 °C). We investigated the effects of different postharvest drying protocols on the metabolites profiling of Ganoderma lucidum using GC-MS, followed by an investigation of the anti-neuroinflammatory potential in LPS-treated BV2 microglial cells. A total of 109 primary metabolites were detected from heat and freeze-dried samples. Primary metabolite profiling showed higher levels of amino acids (17.4%) and monosaccharides (8.8%) in the heat-dried extracts, whereas high levels of organic acids (64.1%) were present in the freeze-dried samples. The enzymatic activity, such as ATP-citrate synthase, pyruvate kinase, glyceraldehyde-3-phosphatase dehydrogenase, glutamine synthase, fructose-bisphosphate aldolase, and D-3-phosphoglycerate dehydrogenase, related to the reverse tricarboxylic acid cycle were significantly high in the heat-dried samples. We also observed a decreased phosphorylation level of the MAP kinase (Erk1/2, p38, and JNK) and NF-κB subunit p65 in the heat-dried samples of the BV2 microglia cells. The current study suggests that heat drying improves the production of ganoderic acids by the upregulation of TCA-related pathways, which, in turn, gives a significant reduction in the inflammatory response of LPS-induced BV2 cells. This may be attributed to the inhibition of NF-κB and MAP kinase signaling pathways in cells treated with heat-dried extracts.     

f(G,T) Gravity with Cylindrically Symmetric Relativistic Fluids

The aim of this paper is to examine the structure scalars with account of f(G, T) theory of gravity. We consider the cylindrically symmetric spacetime with dissipative anisotropic background. We have determined the structure scalars by orthogonally decomposing the Riemann curvature tensor and it is shown that these scalars are associated with fundamental properties of fluid. We further investigate the mass function along with the transport equation and discuss their role on the evolutionary stages of relativistic stellar systems. We have also analyzed these structure scalars for static fluid distributions and it is concluded that all possible solutions of field equations can be expressed through these scalars.