Supramolecular cuboctahedra with aggregation-induced emission enhancement and external binding ability

Beyond the AIE (aggregation-induced emission) phenomenon in small molecules, supramolecules with AIE properties have evolved in the AIE family and accelerated the growth of supramolecular application diversity. Inspired by its mechanism, particularly the RIV (restriction of intramolecular vibrations) process, a feasible strategy of constructing an AIE-supramolecular cage based on the oxidation of sulfur atoms and coordination of metals is presented. In contrast to previous strategies that used molecular stacking to limit molecular vibrations, we achieved the desired goal using the synergistic effects of coordination-driven self-assembly and oxidation. Upon assembling with zinc ions, S1 was endowed with a distinct AIE property compared with its ligand L1, while S2 exhibited a remarkable fluorescence enhancement compared to L2. Also, the single cage-sized nanowire structure of supramolecules was obtained via directional electrostatic interactions with multiple anions and rigid-shaped cationic cages. Moreover, the adducts of zinc porphyrin and supramolecules were investigated and characterized by 2D DOSY, ESI-MS, TWIM-MS, UV-vis, and fluorescence spectroscopy. The protocol described here enriches the ongoing research on tunable fluorescence materials and paves the way towards constructing stimuli-responsive luminescent supramolecular cages.

Beyond the AIE (aggregation-induced emission) phenomenon in small molecules, supramolecules with AIE properties have evolved in the AIE family and accelerated the growth of supramolecular application diversity.     

自主气体轴承控制系统分析及实验研究

提出1种采用音圈电机作为可控节流器的自主电控式气体轴承新方案,可以有效提高大型光电精密仪器回转基准的精度,在实时测量回转基准径向运动误差的同时,通过主动节流器自主调节气场分布而产生控制力和调节轴承的偏移位置,达到减小径向运动量和提高回转精度的目的,同时分析了整个系统数学模型,设计了控制补偿器.采用自主控制方案后,轴承回转精度从控制前的0.3 μm提高到约0.08 μm.结果表明,该轴承系统具有良好动态品质和较高回转精度,能够广泛用于航空航天高精密惯导测试设备中.     

Some Hadamard-Like Inequalities via Convex and s-Convex Functions and their Applications for Special Means

In this study, the author establishes some inequalities of Hadamard-like based on convex and s-convexity in the second sense. Some applications to special means of positive real numbers are also given.     

Laser-induced fluorescence spectrum of nitrogen dioxide in the neighborhood of 6125 Å

The resonance fluorescence spectrum of nitrogen dioxide has been excited by a tunable, cw dye laser in the neighborhood of 6125 Å. The rotational constants of the ²B₂ upper electronic state are determined as follows, in units of cm^?1: A_v′ = 7.2 ± 0.6; $\text{B}\text{?}{}_{\mathrm{v}}\text{′ = 0.454 ± 0.015}$; B_v′ = 0.496 ± 0.046; C_v′ = 0.412 ± 0.019. The band origin is at 16 325.1 ± 1.8. Quoted error limits are standard deviations obtained from the fit of the data. The vibrational assignment of the upper state is (0, 5, 0), and by combination with the data of other workers, we estimate for its vibrational constants, in cm^?1: ω₁′ + x₁₁′ = 1425.7; ω₂′ = 876.6; x₂₂′ = ?0.83; x₁₂′ = ?8.1. The molecular geometry in the upper state is briefly discussed.     

Constant potential primal—dual algorithms: A framework

We start with a study of the primal—dual affine-scaling algorithms for linear programs. Using ideas from Kojima et al., Mizuno and Nagasawa, and new potential functions we establish a framework for primal—dual algorithms that keep a potential function value fixed. We show that if the potential function used in the algorithm is compatible with a corresponding neighborhood of the central path then the convergence proofs simplify greatly. Our algorithms have the property that all the iterates can be kept in a neighborhood of the central path without using any centering in the search directions.Research performed while the author was Ph.D. student at Cornell University and was supported in part by the United States Army Research Office through the Army Center of Excellence for Symbolic Methods in Algorithmic Mathematics (ACSyAM), Mathematical Sciences Institute of Cornell University, Contract DAAL03-91-C-0027, and also by NSF, AFOSR and ONR through NSF Grant DMS-8920550.     

13C NMR: Substituent effects on one-bond 15N?13C coupling constants in anilines and anilinium ions

¹J(¹⁵N¹³C) values obtained from FT ¹³C NMR spectra were measured for a number of ¹⁵N-enriched aniline derivatives and are found to exhibit varying degrees of dependence on the nature of the ring substituent. Theoretical calculations of ¹J(¹⁵N¹³C) values for representative members of the systems examined were made using INDO parameters and a ‘sum-over-states’ perturbation approach. The calculated coupling constants are generally in fair agreement with experimental values when the integral products S_N²(o)S_C²(o) and (r^?3)_N(r^?3)_C have values of 34.437 au^?6 and 2.770 au^?6, respectively.     

Composite weak bosons in neutrino-lepton scattering

We study effects due to a compositeW or/andZ boson in four different leptonic processes where deviations from the standard model (SM) of electroweak unification may be observed. Compositeness is considered through a simple modification of theW andZ gaugeboson propagator, by a form factor depending on a composition scale parameter. We found that all the four processes point out that this type of propagator modification gives an indication of compositeness if Λ≦400 GeV. For Λ>400 GeV, deviation from SM is negligible.     

Electrochemical Properties of Electrode Modified with Langmuir‐Blodgett Film of p‐tert‐Butylcalix[4]arene Derivatives and Its Application in Determining of Silver

A new type of voltammetric sensor, Langmuir‐Blodgett (LB) film of 5,11,17,23‐tetra‐tert‐butyl‐25,27‐di(3‐thiadiazole‐propanoxy)‐26,28‐dihydroxycalix[4]arene modified glassy carbon electrode (LB_TZCA–GCE), was prepared. The electrochemical properties of LB_TZCA–GCE were researched in detail and its recognizing mechanism for silver ion in aqueous solution was discussed. Using this voltammetric sensor, a new stripping voltammetric method for determining of Ag⁺ was erected with good sensitivity, selectivity, reproducibility and recovery. The detection limit was 8×10^?9 M at accumulation time of 180 s. By this method, real samples (lake water, tap water and synthesis sample) were analyzed and the results obtained were well satisfactory.     

Capillary Electrophoretic Determination of Citalopram in Pharmaceutical Tablets and Serum

Determination of citalopram by capillary electrophoresis is described. Compounds were separated at 28 kV in 75 μm i.d. fused silica capillary tubing (total length 85 cm, effective length 65 cm) with 10 mM borate buffer, pH 8.5, containing 10% (v/v) methanol as running buffer. Citalopram and propylparaben (IS) appeared at 3.5 and 5.5 min, respectively. Repeatable linear results were obtained. The limits of detection and quantification were 5.73 × 10⁻⁶ and 1.72 × 10⁻⁵ M, respectively. When citalopram was determined in a pharmaceutical tablet by capillary electrophoresis and by a UV-spectrophotometric method differences between the results were not significant. The citalopram content of tablets was 100.8 ± 2.95% of the label claim. The amount found in serum was 26.7 ± 0.1% of the free drug, indicating that 73.3% of the drug was bound to protein.     

Solid-Phase Extraction and Spectrophotometric Determination of Molybdenum(VI) in Soil and Plant Samples as a Mo(V)-Thiocyanate Complex

A method for the preconcentration and determination of molybdenum(VI) in soil and plant samples using Amberlite XAD-7 resin and spectrophotometry is proposed. Molybdenum was preconcentrated as its Mo(V)-thiocyanate complex using a column containing Amberlite XAD-7 resin and determined spectrophotometrically at 461.0nm in acetone after elution. We investigated several parameters that affect the recovery of molybdenum, such as acidity, amount of reducing and complexing agents, flow rates, volume of sample solution, type and amount of eluent, and the presence of diverse ions. The limit of detection of the proposed method was 38µgL^–1 of molybdenum. The recovery of molybdenum was 98.25±0.05 at 95% confidence level. The highest preconcentration factor was 100 for 250mL of sample volume. The proposed method was applied to soil and plant samples, and molybdenum was determined with a relative error of <3.5%.