Protonation of 1,2-disubstituted imidazolines and other products of condensation of 2-ethylhexanoic acid with diethylenetriamine and triethylenetetramine

The protonation constants for the products of condensation of 2-ethylhexanoic acid with diethylenetriamine or triethylenetetramine were determined by potentiometric titration. The sequence of protonation of the nitrogen atoms in the imidazoline ring was found from the UV, IR, and ¹³C NMR spectra.     

Wet sol–gel silica matrices as delivery devices for phenytoin

Wet sol–gel silica matrices produced under different hydrolysis conditions were used as delivery devices to the active principle of an antiepileptic drug (phenytoin sodium), encapsulated during the condensation stage. Post-incorporation into dry silica powder was an alternative loading procedure. It was proven by infrared spectroscopy that neither the silica network nor the drug loose integrity by encapsulation. The kinetics of in vitro drug release was studied at 37 °C, to water and to artificial cerebrospinal fluid (ACSF). Emphasis has been given to the release to ACSF under dynamic conditions (with fluid renovation, emulating what occurs in the brain). Different delivery regimes were identified and correlated with the loading method and the matrix structure. Matrices with lower total porosity and smaller average pore size proved to be better for a long term release. Renovation of ACSF is relevant to assure a constant concentration of phenytoin in the vicinity of the device.     

餐盒用新型非发泡聚丙烯光降解性能红外光谱法检测

用红外光谱法测试研究了餐盒用新型非发泡聚丙烯光降解行为。结果表明，降解母粒含量不同，其红外吸收光谱图存在明显的差异；在光降解过程中，羰基指数存在明显的动态变化。     

Superiority of zoom lens coupling in designing a novel X-ray image detector

We design a novel X-ray image detector by lens coupling a Gd2O2S:Tb intensifying screen with a high performance low-light-level (L3,which often means luminescence less than 10-3 Lux) image intensifier.Different coupling effects on imaging performance between zoom lens and fix-focus lens are analyzed theoretically.In experiment,for designing a detector of 15-inch visual field,the system coupled by zoom lens is of 12.25-1p/cm resolution,while the one with fix-focus lens is 10 lp/cm.The superiority of zoom lens is validated.It is concluded that zoom lens preserves the image information better than fix-focus lens and improves the imaging system's performance in this design,which is referential to the design of other optical imaging systems.     

Transformations in the space of almost convergent sequences

Under consideration is the space of almost convergent sequences as well as the operators acting on it. We prove that the space is invariant under the transformations of some class including, in particular, the Hardy and averaging operators.     

A weak Kantorovich existence theorem for the solution of nonlinear equations

The Kantorovich theorem is a fundamental tool in nonlinear analysis for proving the existence and uniqueness of solutions of nonlinear equations arising in various fields. This theorem was weakened recently by Argyros who used a combination of Lipschitz and center-Lipschitz conditions in place of the Lipschitz conditions of the Kantorovich theorem. In the present paper we prove a weak Kantorovich-type theorem that gives the same conclusions as the previous two results under weaker conditions. Illustrative examples are provided in the paper.     

On the Tannic Acid Interaction with Metallic Iron

The reaction between tannic acid and metallic iron was studied using infrared and Mössbauer spectroscopy. Iron converts to sparingly soluble and amorphous ferric tannate complexes. The degree of conversion was followed from 1 day to 6 months. In the very early stages of reaction the product consists of a mono-type complex, while in the later stages a mixture of mono- and bis-type complexes were formed. The conversion reaction of metallic iron to tannate complexes follows a first-order reaction kinetics.     

High resolution imaging of contact potential difference using a novel ultrahigh vacuum non-contact atomic force microscope technique

An ultrahigh vacuum scanning Kelvin probe force microscope (UHV SKPM) based on the gradient of electrostatic force was developed using the technique of a UHV non-contact atomic force microscope (NC-AFM) capable of atomic level imaging, and used for simultaneous observation of contact potential difference (CPD) and NC-AFM images. The CPD images with a potential resolution of less than 10 meV were observed in the UHV SKPM, demonstrating an atomic level resolution. The change of potential corresponding to the charges on the insulated surface of polypropylene have been observed in UHV SKPM. We also demonstrated a reliable method to obtain the CPD from the bias voltage dependence curves of the frequency shift in all of the scanning area. The results are consistent with comparing the barrier height images in that the work functions of adatoms are greater than the work function of corner holes.