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71.
Michele Colturato 《Mathematical Methods in the Applied Sciences》2020,43(10):6598-6626
We consider the sliding mode control (SMC) problem for a diffuse interface tumor growth model coupling a Cahn–Hilliard equation with a reaction–diffusion equation perturbed by a maximal monotone nonlinearity. We prove existence and regularity of strong solutions and, under further assumptions, a uniqueness result. Then, we show that the chosen SMC law forces the system to reach within finite time a sliding manifold that we chose in order that the tumor phase remains constant in time. 相似文献
72.
External electric field(EEF) has shown its advantages in tuning chemical reaction as an efficient and feasible-to-control tool. In this paper, we explored the mechanisms of three EEF-regulated Diels-Alder reactions including two traditional-DA reactions to form two C-C single bonds and a hetero-DA reaction to form both a C-C and a C-O bond, respectively, and introduced an EEF contribution decomposition(ECD) model to understand how the EEF coupled with the intrinsic nuclear and electronic redistributions so as to affect chemical reaction. The ECD model, by decomposing the overall EEF effects into geometry re-equilibrium and static induction parts, can give a clear and quantitative picture of a physical quantity change upon EEF, as demonstrated on relative energies, activation barriers, charge distribution and dipole moments. The ECD analyses will shed light on the effective tuning of chemical reactions by the electric field. 相似文献
73.
ABSTRACT Multicolour emissive carbon dots (CDs) are widely investigated by virtue of their merits on fluorescent properties. Method on heteroatom doping assisted with various solvents has been proved efficient in achieving multiple-colour-emissive CDs, especially long-wavelength emission. Herein, a synthesis of multicolour-emissive CDs by controlled surface function is reported. By tuning the thermal-pyrolysis temperature and molar ratio of reactants, optimal emission of the resulted CDs gradually shifts from blue to yellow light with the assistance of different solvents. According to the emissive relationship dependent on excitation, fluorescence lifetimes, and FT-IR of these CDs, the different surface states participated with S and N elements on the surface of carbogenic core govern fluorescent colours of the CDs. In terms of the applications, blue CDs (B-CDs) exhibits high sensitivity for ion detections of Ag+ and Fe3+, which is further illustrated to have different quenching mechanisms each other because that these ions have the affinity interaction with different surface groups of the CDs. Moreover, blue and yellow CDs solutions are mixed with PVP water solution to fabricate white-light CDs/PVP film, which exhibits stable fluorescence with a CIE coordinate of (0.32, 0.33) and endows these CDs as potentially fluorescent nanomaterial in the solid state lighting field. 相似文献
74.
Hybrid nanoparticles (HNPs) with zinc oxide and polymethyl metha acrylate (inorganic/ polymer) were synthesized through the exploitation of ultrasound approach. The synthesized HNPs were further characterized employing transmission electron microscopy and x-ray diffraction. ZnO-PMMA based HNPs exhibit excellent protection properties to mild steel from corrosion when gets exposed to acidic condition. Electrochemical impendence spectroscopy (EIS) analysis was accomplished to evaluate the corrosion inhibition performance of MS panel coated with 2 wt% or 4 wt% of HNPs and its comparison with bare panel and that of loaded with only standard epoxy coating., Tafel plot and Nyquist plot analysis depicted that the corrosion current density (Icorr) decreases from 16.7 A/m2 for bare material to 0.103 A/m2 for 4% coating of HNPs. Applied potential (Ecorr) values shifted from negative to positive side. These results were further supported by qualitative analysis. The images taken over a period of time indicated the increase in lifetime of MS panel from 2 to 3 days for bare panel to 10 days for HNPs coated panel, showing that ZnO-PMMA HNPs have potential application in metal protection from corrosion by forming a passive layer. 相似文献
75.
76.
LI Yuan LI Ruizhe LI Zhenhua WEI Weiqin OUYANG Shuxin YUAN Hong ZHANG Tierui 《高等学校化学研究》2020,36(6):1006-1012
Photothermal Fischer-Tropsch synthesis(FTS) has been extensively studied, but few reports were focused on systematically exploring the influence of support on catalytic performance. Herein, a series of Fe5C2-based catalysts with different supports was fabricated via a one-step wet-chemical method for photothermal conversion of syngas to lower olefins. Under light irradiation, the optimized Fe5C2/α-Al2O3 catalyst demonstrated remarkable photothermal FTS activity, delivering selectivity to lower olefins of 50.3% with a CO conversion rate of 52.5%. Characterization studies using X-ray diffraction and Mössbauer spectroscopy analysis revealed that the active catalyst mainly contained Fe5C2 nanoparticles on α-Al2O3 support. It was found that the weak interaction between active phase and α-Al2O3 could promote the formation of Fe5C2, which contributed to the high selectivity to lower olefins. 相似文献
77.
Benni Du 《Molecular physics》2020,118(2)
Kinetics and mechanism of the gas-phase reaction of CH3C(O)OCH(CH3)CH2OCH3 (MPA) with OH radicals in the presence of O2 and NO have been investigated theoretically by performing a high and reliable level of theory, viz., CCSD(T)/6-311?+?G(d,p)//BH&HLYP/6-311++G(d,p)?+?0.9335×ZPE. The calculations predict that the H-abstraction from the ?CH2?O? position of MPA is the most facile channel, which leads to the formation of the corresponding alkoxy radicals CH3C(O)OCH(CH3)C(O ?)HOCH3 under atmospheric conditions. This activated radicals CH3C(O)OCH(CH3)C(O ?)HOCH3 will undergo further rearrangement, fragmentation and oxidative reactions and predominantly leads to the formation of various products (methyl formate HC(O)OCH3 and acetic anhydride CH3C(O)OC(O)CH3). In the presence of water, acetic anhydride can convert into acetic acid CH3C(O)OH via the hydrolysis reaction. The calculated total rate constants over the temperature range 263–372?K are used to derive a negative activation energy (Ea= ?5.88 kJ/mol) and an pre-exponential factor (A?=?1.78×10?12 cm3 molecule?1 s?1). The obtained Arrhenius parameters presented here are in strong agreement with the experimental values. Moreover, the temperature dependence of the total rate constant over a temperature range of 263?1000?K can be described by k?=?5.60 × 10?14×(T/298?K)3.4×exp(1725.7?K/T) cm3 molecule?1 s?1. 相似文献
78.
A. Othman Almatroud Amina-Aicha Khennaoui Adel Ouannas Giuseppe Grassi M. Mossa Al-sawalha Ahlem Gasri 《Entropy (Basel, Switzerland)》2020,22(12)
This article proposes a new fractional-order discrete-time chaotic system, without equilibria, included two quadratic nonlinearities terms. The dynamics of this system were experimentally investigated via bifurcation diagrams and largest Lyapunov exponent. Besides, some chaotic tests such as the 0–1 test and approximate entropy (ApEn) were included to detect the performance of our numerical results. Furthermore, a valid control method of stabilization is introduced to regulate the proposed system in such a way as to force all its states to adaptively tend toward the equilibrium point at zero. All theoretical findings in this work have been verified numerically using MATLAB software package. 相似文献
79.
80.
CHEN Jianfei CHEN Xiaoyu ZHANG Xing YUAN Yao BI Ruyi YOU Feifei WANG Zumin YU Ranbo 《高等学校化学研究》2020,36(1):120-126
BiVO4,a promising visible-light responding photocatalyst,has aroused extensive research interest because of inexpensiveness and excellent chemical stability.However,its main drawback is the poor photoinduced charge-transfer dynamics.Building nanostructures is an effective way to tackle this problem.Herein,we put forward a new method to prepare nanostructured BiVO4 from Bi-based metal-organic frameworks[Bi-MOF(CAU-17)]precursor.The as-prepared material has a rod-like morphology inherited from the Bi-MOF sacrificial template and consists of small nanoparticle as building blocks.Compared with its counterparts prepared by conventional methods,MOF-derived nanostructured BiVO4 shows better light absorption ability,narrower bandgap,and improved electrical conductivity as well as reduced recombination.Consequently,BiVO4 nanostructure demonstrates high photocatalytic activity under visible light towards the degradation of methylene blue.Methylene blue can be degraded up to 90%within 30 min with a reaction rate constant of 0.058 min-1.Moreover,the cycling stability of the catalyst is excellent to withstand unchanged degradation efficiency for at least 5 cycles. 相似文献