Part 1: The Principles of the Method

Although the principle of the concentration measurement of the elements having great neutron cross sections, e.g. Li, B, Cd, by the method of thermal neutron flux attenuation is well known, some difficulties are encountered in its practical application. These arise mainly because of the influence of the geometry conditions on the measurement.     

Silicon-29 NMR Study of Alkaline Aqueous and Alcoholic Tri-butylmethyl Ammonium (TBMA) Silicate Solutions

Silicon-29 NMR spectroscopy was used to characterize aqueous and alcoholic alkaline solutions of tri-butylmethyl ammonium (TBMA) silicates. The effect of TBMA cation on the equilibrium of silicate oligomers in aqueous alkaline silicate solutions was investigated using ²⁹Si NMR spectra. It was found that TBMA cation has a structure directing role and directs the silicate species to form minor amounts of silicate anion in the presence of high concentration of silicon. Silicon-29 NMR spectra of TBMA silicate solutions indicate that considerable changes occurred by changing the Si/TBMA ratio. The distribution of silicate species was affected by the presence of the alcohols, specifically methanol.     

Structural Study on 5-(Dodecyloxy)-1-((6-Trimethylammonio)Hexyl)oxy)Naphthalene—Sodium Dextran Sulfate Langmuir-Blodgett Film Through Fourier Transform Infrared Spectroscopy

The Fourier transform infrared transmission (FTIR-T) and attenuated total reflection (ATR) spectra of the 5-(dodecyloxy)-1-((6-(trimethylammonio)hexyl)oxy)naphthalene — sodium dextran sulfate composite LB films deposited under the surface pressure of 30 mN/m have been recorded and spectral assignments made. By means of polarization techniques and with the application of the uniaxial and biaxial orientation models, the orientation characteristics of the long hydrocarbon chains and the = C-O linkage in the LB films have been investigated, giving rise to the detailed information of the arrangement of molecular fragments in the 1-SDS composite LB films.     

Crystallization Morphology and Behavior of Polypropylene Composites Containing Microencapsulated Flame Retardant

With shells of melamine-formaldehyde (MF), urea-melamine-formaldehyde (UMF), or poly(vinyl alcohol)-melamine-formaldehyde (VMF), microencapsulated ammonium polyphosphate (APP) was prepared by in-situ polymerization for use as a flame retardant in polypropylene (PP). Microencapsulated APP showed rougher surface, smaller size, and narrower size distribution compared with APP. The results of polarized optical microscopy (POM) showed that the additives resulted in a decrease of the spherulite size and less perfection in crystal geometry of PP composites. Due to the interaction and alignment of the PP polymer chains at the surface, the surface modification of APP influenced the formation and further development of PP crystals remarkably. The crystallization and melting behaviors of the PP composites were affected by the rough surface of the microencapsulated APP, which was helpful for the formation of β-crystals and decreased the crystal growth rate compared with APP.     

阳离子表面活性剂三甲基溴化铵与硝酸铵相互作用的表面和热力学研究

本文系统研究了阳离子表面活性剂三甲基溴化铵和硝酸铵盐的表面现象和自聚集行为. 采用电导法和表面张力法研究在不同温度下阳离子表面活性剂三甲基溴化铵的表面性质和热力学性质. 通过表面张力测定得到临界胶束浓度、吸附自由能、胶束化的自由能、最小分子面积和表面过量浓度. 该研究表明,胶束化过程是自发放热反应. 电导测定结果确定了临界胶束浓度、电离程度和反离子结合度. 加入硝酸铵盐至表面活性剂溶液后,临界胶束浓度降低,电离程度和反离子结合度增加,更加有利于胶束化过程的自发. 该研究对进一步理解电解质和表面活性剂之间相互作用具有重要意义.     

Preparation of Multi-Functional Quaternary Ammonium Chitosan/Surfactin Hydrogel and its Application in Wound Management

Hydrogel with a 3D network structure can cover the wound to stop the bleeding and support the host tissue infiltration and integration. In this study, an antibacterial hydrogel with hemostasis and the ability to promote wound healing is proposed. This hydrogel comprised surfactin, polyvinylpyrrolidone, and methacrylic anhydride (MA) grafted quaternary ammonium chitosan (CS-MA). The hydrogel formation is triggered by the ultraviolet-initiated polymerization of CS-MA, while the surfactin is complexed with the hydrogel through hydrogen bonding interaction. The results showed that this hydrogel is an adhesive hydrogel with shape adaptability, which can cover the wound surface and promote contact between the hydrogel and the wound surface. More importantly, this hydrogel can simulate the microenvironment of the primary extracellular matrix and increase collagen deposition, and inflammatory factor transformation. The designing of such a multi-functional hydrogel is expected to provide a novel approach to promoting the healing of wounds.     

Cerium(IV)ammonium nitrate(CAN)initiated O-alkylation of oximes with N-vinyl lactams

O-Alkylation of oximes with N-vinylpyrrolidin-2-one or iV-methyl-N-vinylacetamide was efficiently initiated by a catalytic amount of cerium(IV)ammonium nitrate(CAN), giving the corresponding oxime ether derivatives in good yield.     

Efficiently removing cetyl trimethyl ammonium bromide from wastewater by graphene oxide

Cetyl trimethyl ammonium bromide (CTAB) containing wastewater from dressing plant may pose a detrimental threaten to mineral beneficiation and environment. The adsorption of CTAB in aqueous solutions by graphene oxide (GO) has been studied in this work. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectrometer, and atomic force spectroscopy were used to characterize GO. The results indicated that the adsorption followed the Freundlich model could be well described by pseudo-second order kinetic model. The adsorption capacity was much bigger than activated carbon and many natural clay minerals. The adsorption process was endothermic, and the adsorption mechanism of CTAB onto GO was proven to be controlled by surface complexation, hydrogen bonding, and electrostatic attraction.     

Energy - dispersive X - ray diffraction of the ammonium - halides under pressure

Abstract

The structure of the ammonium halides NH₄X (X = Cl, Br, I) has been studied under pressure up to 40 GPa by energy dispersive X-ray diffraction using synchrotron radiation. Equations of state and a discussion on the possible structure of phase V will be presented.