Design,synthesis and structure of novel dendritic G-2 melamines comprising piperidine motifs as key linkers and 4-(n-octyloxy)aniline as a peripheral unit

Starting from 4-amino-1-(tert-butoxycarbonyl)piperidine (Boc-PD-NH₂), we report the synthesis of three novel meta-tri- and dimeric tetravalent N-substituted melamines with piperidin-4-yl groups. These compounds were used as central building-blocks and successfully incorporated into three new G-2 melamine dendrimers containing 4-(n-octyloxy)aniline as a peripheral unit. From a structural point of view, the challenging reactivity of Boc-PD-NH₂ in comparison with 1-Boc-piperazine and cyclohexylamine, as S_N2-Ar amination reagents against cyanuric chloride, was interpreted in terms of DFT (Density Functional Theory) thermodynamic and electronic computed data. Two out of the three dendrimers self-assembled in the solid state as large homogeneously packed spherical nano-aggregates (average D values ranging between 2500 and 3200 nm, TEM (Transmission Electron Microscopy) data) as a result of their “shell-to-shell” pre-associations in solution (DMF and 1,4-dioxane), promoted by chiral self-organisation, “round”- or “oval”-vaulted shapes (DFT data).     

Permutation trinomials over Fq3

We consider four classes of polynomials over the fields ${\mathbb{F}}_{q^3}$, $q=p^h$, $p>3$, $f_1(x)=x^{q^2+q-1}+A{x}^{q^2-q+1}+Bx$, $f_2(x)=x^{q^2+q-1}+A{x}^{q^3-q^2+q}+Bx$, $f_3(x)=x^{q^2+q-1}+A{x}^{q^2}-Bx$, $f_4(x)=x^{q^2+q-1}+A{x}^q-Bx$, where $A,B\in {\mathbb{F}}_q$. We find sufficient conditions on the pairs $(A,B)$ for which these polynomials permute ${\mathbb{F}}_{q^3}$ and we give lower bounds on the number of such pairs.     

Some results on divisor problems related to cusp forms

The Ramanujan Journal - Let $$\lambda _{f}(n)$$ be the normalized Fourier coefficients of a holomorphic Hecke cusp form of full level. We study a generalized divisor problem with $$\lambda...     

Theoretical study of the effect of the Coulomb blockade and Kondo resonance in the density of states using self-consistent field approximation

In a recent paper, we theoretically investigated the density of states of the composite channel–contact system in the Coulomb and Kondo regimes using the self-consistent field approximation. There are the main experimental observations of vibration features in the Coulomb blockade [H. Park et al., Nature (London) 407, 57 (2000)] and Kondo [L. H. Yu et al., Phys. Rev. Lett. 93, 266802 (2004)] regimes. In the Kondo regime, our results show that one peak at $E=\mu$ can be observed in the density of states at low temperatures (0.0026 eV ≤ k_BT ≤ 0.0000026 eV). Also, the real part of ∑₃ has one minimum peak at $E=-\mu$ and the real par of ∑₂ has one maximum peak at $E=-\mu$ for 0.01 ≤ μ ≤ 0.07 in the Kondo regime at low temperatures.     

Self-normalized Cramer-type Moderate Deviations for Functionals of Markov Chain

Let{xn,n≥0}be a Markov chain with a countable state space S and let f(·)be a measurable function from S to R and consider the functionals of the Markov chain yn:=f(xn).We construct a new type of self-normalized sums based on the random-block scheme and establish a Crame′r-type moderate deviations for self-normalized sums of functionals of the Markov chain.     

A theoretical study on the pure and doped ZnO nanoclusters as effective nanobiosensors for 5-fluorouracil anticancer drug adsorption

The electronic sensitivity and effectiveness of the pristine, Fe,- Mg-, Al- and Ga-doped ZnO nanoclusters interacted with 5-fluorouracil (5-FU) anticancer drug are theoretically investigated in the gas phase using the B3LYP/wB97XD density functional theory calculations with LANL2DZ basis set. It is concluded that 5-FU adsorption on the doped nanoclusters has relatively higher adsorption energy as compared with the pristine zinc oxide. A number of thermodynamic parameters, such as band gap energy (E_g), adsorption energy (E_ad), molecular electrostatic potential, global hardness (η) and density of electronic states, are attained and compared. Also, calculated geometrical parameters and electronic properties for the studied systems indicate that Mg- and Ga-doped Zn₁₂O₁₂ present higher sensitivity to 5-FU compared with the pristine nanocluster. Theoretical results reveal that adsorption of 5-FU on the doped nanoclusters is influenced by the electronic conductance of the nanocluster. Therefore, Mg- and Ga-doped ZnO can be considered as promising nanobiosensors for detection of 5-FU in medicine.     

基于分子工程的方法设计首例具有Sr2Be2B2O7 (SBBO)结构的深紫外氟碳酸盐双折射晶体AMgLi2(CO3)2F (A=K,Rb)※

分子结构设计是开发新化合物和通过原子尺度操纵优化晶体结构的一种引人注目的策略. 在这个工作中, 利用分子工程的思想, 基于SBBO结构, 成功设计并合成两个新型氟碳酸盐KMgLi₂(CO₃)₂F和RbMgLi₂(CO₃)₂F. 在两个结构中, a-b平面是由CO₃和LiO₃F阴离子基团组成的无限[Li₃C₃O₆F₃]_∞层, 进一步相邻的层通过F原子连接形成一个独特的[Li₆C₆O₁₂F₃]_∞双层. 这种结构特征对改善晶体的层状生长习性和消除晶体的多晶性有很大的帮助. 光学测试表明, 该系列晶体具有大的双折射和短的紫外截止边, 是深紫外双折射晶体良好的候选材料.     

Nitrogen Donor Protection for Atomically Precise Metal Nanoclusters

Surface organic ligands are critical in dictating the structures and properties of atomically precise metal nanoclusters. In contrast to the conventionally used thiolate, phosphine and alkynyl ligands, nitrogen donor ligands have not been used in the protection for well-defined metal nanoclusters until recently. This review focuses on recent developments in atomically precise metal nanoclusters stabilized by different types of nitrogen donor ligands, in which the synthesis, total structure determination and various properties are covered. We hope that this review will provide insights into the rational design of N donor-protected metal nanoclusters in terms of structural and functional modulation.     

The comparable structural,elastic anisotropic and thermophysical properties of advanced U–Si fuel to baseline UO2: a DTF method

The European Physical Journal B - Molecular dynamics and Monte Carlo methods are common measurements to study the diffusion coefficients of the fluid particles under restricted conditions. Here,...