Simple Solutions

Pacific Rim leaders meet in Peru, vowing to solve economic problems through enhanced cooperation

Existence of Exactly n+1 Simple 4-Periodic Solutions of the Differential Delay Equation x(t)=-f(x(t-1))

By discussing the zeros of periodic.solutions we give in this paper a criterion for the existence of exactly n+1 simple 4-periodic solutions of the differential delay equation x(T)= -f(x(t-1)).

Facile synthesis and highly efficient selective adsorption properties of Y2Mo4O15 for methylene blue：Kinetics,thermodynamics and mechanical analyses

Y2 Mo4 O15 particles were prepared using a simple solution method（SSM） and used as a highly efficient selective adsorbent for methylene blue（MB） in aqueous solutions. The maximum adsorption capacity of the samples was determined based on the adsorption isotherms with different adsorbent doses at 298,318 and 338 K. The fittings of the temperature-dependent isotherms yield ΔrGm^θ=-34.1 kJ/mol,ΔrHm^θ-36.9 kJ/mol and ΔrSm^θ=-9.67 J/mol·K. The as-prepared Y2 Mo4 O15 has a very large maximum adsorption capacity（i.e., 198 mg/g） for MB at room temperature, and this value is only less than that of amorphous hardwood powder. Notably, 80 mg of adsorbent is able to completely decolorize 250 mL of 30 mg/L MB aqueous solution. The kinetic parameters of the adsorption process were obtained from the temperature-dependent adsorption isotherm（i.e., E1=26.9 kJ/mol and E1 = 63.8 kJ/mol）. The results of adsorption kinetics show that it is a pseudo-second-order reaction. The mechanism of the high selectivity and the large adsorption capacity is discussed based on competitive ion（CI） experiments and coordination theory.

Synthesis and Absorption Properties of Leaf-like Nd2Cu2O4+δ via a Coordination Complex Method with [NdCu(3,4-pdc)2(OAc)(H2O)5]·6.5H2O Precursor

Nd2Cu2O4+δnanosheets were synthesized via coordination complex method(CCM)by using[NdCu(3,4-pdc)2(OAc)(H2O)5]·6.5H2O(1,3,4-pdc=3,4-pyridinedicarboxylic acid)as the precursor.Compared to the particles prepared by SSM(simple solution method),Nd2Cu2O4+δprepared by CCM showed leaf-like morphology composed of nanosheets with an average thickness of 50~80 nm and a BET surface area up to 17.9 m^2/g.The Nd2Cu2O4+δsamples exhibit selective adsorption towards malachite green(MG)with significant Qm(maximum adsorption capacity)values reaching up 1.55 g/g at room temperature,and the thermodynamic parameters of adsorption process were obtained.In addition,the properties of selective adsorption of the prepared samples were investigated by temperature change tests.

Global Exact Boundary Controllability for General First-Order Quasilinear Hyperbolic Systems

For general first-order quasilinear hyperbolic systems,based on the analysis of simple wave solutions along characteristic trajectories,the global two-sided exact boundary controllability is achieved in a relatively short controlling time.