Surface Properties of Novel Surfactant, Dihexadecyl Gemini Phosphate, Monolayers on Water Surface by Dropping Method

We have synthesized first novel dihexadecyl phosphate (DHGP-n) gemini surfactants containing alkyl chain ((CnH2n);n = 3, 4, 5, and 6) spacers. Surfactants were used to form monolayers on water surface. Surface tension measurement (STm), Brewster angle microscopy (BAM), and density functional theory (DFT) calculation were used to investigate these monolayers. Surface pressure (π) and molecular area (A);π-A isotherm curves of all DHGP-n gemini surfactants showed a gradual increase in surface pressure without any break points in the curves, confirmed the formation of liquid-expand (LE) type monolayers. BAM observations also supported the STm results. Limited molecular area (A0) of these monolayers depended on the spacer of gemini surfactants without spacer n = 4. Longer alkyl chain spacer in the series had higher value of A0 in π-A isotherm plots. In the series, A0 of spacer n = 4 was smallest among A0 values of other spacers. Density functional theory (DFT) method calculation also confirmed π-A isotherm curves pattern of these surfactants. Calculation showed that both odd and even numbers and length of the alkyl chain spacer influenced the structure of DHGP-n monolayer formation on the water surface.

Direct Production of High Pressure Hydrogen at Great Rate from Glycerol/Water/Metal Mixture

One of the key issues facing the global society today is to find renewable and sustainable energy sources. Hydrogen has gained much attention in recent years since it is one of fuels for fuel cells. It emits no carbon dioxide when it is used and so on. In this study, a great rate production of high pressure hydrogen rich gas from glycerol/water/metal mixtures was developed since glycerol has become one of the enormous industrial by-products, especially from biodiesel processing plants. It was found that cobalt was the optimum metal additive among tested metals of aluminum, cobalt, magnesium and nickel in terms of a hydrogen producing rate, a hydrogen partial pressure and a conversion ratio from 50 mol% glycerol/water mixtures under an operating temperature of 723 K. Concretely, hydrogen rich gas with concentration about 64%H2 and high partial pressure about 4 MPaN,H2 could be produced at the great producing rate of 42.9 LN,H2 dm-2min-1 and high conversion ratio about 60%H2. All the produced hydrogen rich gases from glycerol/water/metal mixtures were by no means inferior to pure hydrogen as a fuel for the polymer elec-trolyte fuel cell.

Superfunctional high-entropy alloys and ceramics by severe plastic deformation

High-entropy alloys and ceramics containing at least five principal elements have recently received high attention for various mechanical and functional applications.The application of severe plastic deformation(SPD),particularly the high-pressure torsion method,combined with the CALPHAD(calculation of phase diagram) and first-principles calculations resulted in the development of numerous superfunctional high-entropy materials with superior properties compared to the normal functions of engineering materials.This article reviews the recent advances in the application of SPD to developing superfunctional high-entropy materials.These superfunctional properties include(ⅰ) ultrahigh hardness levels comparable to the hardness of ceramics in high-entropy alloys,(ⅱ) high yield strength and good hydrogen embrittlement resistance in high-entropy alloys;(ⅲ) high strength,low elastic modulus,and high biocompatibility in high-entropy alloys,(ⅳ) fast and reversible hydrogen storage in high-entropy hydrides,(ⅴ) photovoltaic performance and photocurrent generation on high-entropy semiconductors,(ⅵ) photocatalytic oxygen and hydrogen production from water splitting on high-entropy oxides and oxynitrides,and(ⅶ)CO_(2) photoreduction on high-entropy ceramics.These findings introduce SPD as not only a processing tool to improve the properties of existing high-entropy materials but also as a synthesis tool to produce novel high-entropy materials with superior properties compared with conventional engineering materials.

Enhanced electrical property of graphite/Al_(2)O_(3) composite fabricated by reductive sintering of gel-casted body using cross-linked epoxy polymer

In the present study,graphite/alumina composites are fabricated via reductive sintering of gel-casted green bodies with structurally controlled cross-linked epoxy polymers for the first time.The cross-linking degrees of polymers are tuned by the amount ratio of epoxy monomer/polyvinyl alcohol cross-linker utilized in gel-casting process.Superior electrical properties with respect to 5-fold enhanced electrical conductivity and 2-fold higher carrier mobility are successfully achieved in graphite/alumina composite fabricated from cross-linked epoxy polymer,whose phenomenon is attributed to the excellent conductive path in ceramic matrix established by highly uniform network with improved graphitization degree.