Precursor state of skyrmions in MnSi: a heat capacity study

The magnetic phase diagram of MnSi based on the detailed magneto‐heat capacity study is presented. It shows the A‐phase, a precursor to the formation of stable skyrmion lattice, along with the intermediate, helical, conical, ferromagnetic and paramagnetic phases. The field isotherms of specific heat in and around the transition temperature reveal the different magnetic modulations. The local minima represent the relatively low entropy state due to the formation of A‐phase as a precursor to the stable skyrmion lattice. The field‐induced second‐order phase transition is observed by melting the intermediate phase. The region of existence of first‐order phase transition is found to be, effectively, from helical to the intermediate phase. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of β-Nucleating Agent on the Crystallization,Mechanical Properties,and Heat Resistance of Injection-Molded Isotactic Polypropylene

Injection-molded β-isotactic polypropylene (β-iPP) was prepared with a commercial β-nucleating agent (NT-A). The effect of NT-A on the crystallization, mechanical properties, and heat resistance of β-iPP was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), polarized light microscopy (PLM), and mechanical and heat deflection tests. DSC and WAXD analysis showed that the content of β-crystals in the nucleated iPP was higher than that of pure iPP, and the content of β-crystals of the core was higher than that of the skin. PLM observations showed that injection-molded iPP had an obvious skin-core structure. NT-A induced abundant β-crystals and resulted in small spherulites which improved the Izod notched impact strength. When the content of NT-A was 0.075wt%, the Izod notched impact strength reached a maximum, 2.6 times more than that of pure iPP. The heat distortion temperature was also improved by NT-A.     

Determination of the Heat of Adsorption and Desorption of a Volatile Organic Compound Under Dynamic Conditions Using Fourier‐Transform Infrared Spectroscopy

Quantitative Fourier‐transform infrared spectroscopic analysis was used for the determination of adsorption capacity of a model volatile organic compound (VOC) under dynamic conditions. The analytical method used also offers the possibility of distinguishing between reversible and irreversible adsorption as well as further detection of adsorbed VOC transformation. The obtained adsorbed amounts have been used for the determination of the heat of adsorption and the activation energy of desorption using, respectively, isosteric and temperature programmed desorption methods. The approach has been applied to explore the potential use of local clay as an adsorbent material for VOC pollutants.     

A Double Isotopic Labelling Study of the Infrared Spectra of the Linkage Isomers [Pd(bipy)(SCN)2], [Pd(bipy)(NCS)2] and Related Complexes

Abstract

The IR spectra of the linkage isomers [Pd(bipy)(SCN)₂] and [Pd(bipy)(NCS)₂] have been determined in the C≡N stretching region (2200–2000 cm^?1) and below 500 cm^?1. The band shifts resulting from deuteration of the 2,2′-bipyridine (bipy) ring and ¹⁵NCS-labelling are shown to provide a ready means for distinguishing between the internal ligand modes, the μPd-N(bipy) and μPd-SCN/μPd-NCS vibrations. The assignment technique has been further extended to the complexes [Pt(bipy)(SCN)₂] and [Pd(phen)(SCN)₂] (phen = 1,10-phenanthroline). Finally, a comparison between the IR spectra of [Pd(bipy)(NCO)₂], [Pd(bipy)(NCS)₂] and [Pd(bipy)(SCN)₂] reveals that the frequencies μM-NCO, μM-NCS and μM-SCN decrease in the sequence NCO > NCS > SCN.     

A comparative in vitro study of the digestibility of heat- and high pressure-induced gels prepared from industrial milk whey proteins

We undertook this study to compare the digestibility of heat- and high pressure-induced gels produced from whey protein isolate (WPI). To simulate in vivo gastrointestinal digestion of WPI gels, a pepsin–trypsin digestion system was used. The in vitro protein digestibility of WPI gels induced by high pressure (400 MPa and 30 min; P-gel) and those induced by heat (80°C and 30 min; H-gel) was compared using a protein concentration of 0.14 g mL^?1. The in vitro protein digestibility of P-gels was significantly greater than that of H-gels (p<0.05). The size-exclusion chromatography profiles of the hydrolysates showed that the P-gel generated more and smaller peptides than natural WPI and H-gels. Furthermore, Sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis showed some soluble disulfide-mediated aggregation in the P-gel, while there was more insoluble aggregation in the H-gel than the P-gel. The P-gel was more sensitive to proteinase than the H-gel, which was related to the content of S–S bonds, and this in turn could be attributed to the differences in the gelation mechanism between the H-gel and P-gel.     

Specific heat of liquid hexane up to 500 MPa and from 243 to 473 k from the heat of compression

Abstract

The expansivity of n-hexane was measured through the heat of compression up to 500 MPa in the 243–473 K temperature range. Details about the experiment are given. From the fit to our data, the pressure variation of the specific heat C_p, in the same pressure-temperature domain, is computed; good agreement is obtained with available high pressure data.     

Parametric study on a compound-drop spray flame

The introduction of compound-drop spray in a combustion system is a new concept. These droplets bear two gasification stages to cause an integral positive or negative effect on a premixed flame to raise or lower the local temperature of the gasification region. In this paper, we adopt a compound drop which contains a water core encased by a layer of shell fuel. A one-dimensional homogeneous lean or rich premixed flame with the dilute compound-drop spray was investigated by using large activation energy asymptotic analysis. The compound-drop spray burning mode was defined and divided into completely pre-vaporised burning (CPB), shell pre-vaporised burning (SPB) and shell partially pre-vaporised (SPP) burning modes by way of the gasification zones of the shell fuel and the core water relative to the flame position. The influences of the initial droplet radius, the shell-fuel mass fraction and the liquid loading of the compound-drop spray on the lean and rich flames were analysed. By means of the normalisation parameter of flame propagation mass flux (), enhancement, suppression or extinction of the compound-drop spray flame can be represented clearly. Furthermore, from the observation of extinction, the necessary conditions of extinction of a lean spray flame by the internal heat transfer are that the spray is a negative effect and causes a sufficient heat loss rate at flame sheet downstream side. For a rich spray flame, three extinction patterns were observed; they occur in SPP, SPB or at the critical SPB mode, but do not in CPB. The extinction maps of the compound-drop spray demarcate the patterns and also indicate the limitations and corresponding conditions of the flame extinction.     

Comment on “Role of the velocity frame of reference in thermodiffusion in liquid mixtures” by M. Eslamian,C.G. Jiang and M.Z. Saghir

We analyze the material transport equations (MTE) derived by Eslamian and co-authors and address the criticism expressed regarding the approach formulated in our previous work. In doing so, we show that the MTE formulated by Eslamian and co-authors are valid only in closed stationary non-isothermal systems in combination with the restrictions on the Onsager coefficients formulated in our work which is criticized, and that for non-stationary systems the approach we took can be used.     

Effect of solute atoms on grain boundary sliding in magnesium alloys

The effect of solid-solution alloying on grain boundary sliding (GBS) was investigated using pure magnesium and six kinds of Mg–X (X?=?Ag, Al, Li, Pb, Y and Zn) dilute binary solid solutions with an average grain size of 10?µm. A sharp increase in damping capacity caused by GBS was observed above a certain temperature. The temperature at which a sharp increase in damping capacity occurred depended on the alloying element. The addition of Y and Ag markedly increased the onset temperature (more than 100?K) for a sharp increase in damping capacity, whereas the addition of Zn, Al and Li slightly increased the onset temperature (less than 50?K) as compared with that for pure magnesium. Tensile tests at a temperature of 423?K revealed that the higher the onset temperature, the lower the strain rate sensitivity of the flow stress. It is suggested that the former elements (Y and Ag) are more effective in suppressing GBS in magnesium alloys than the latter ones (Zn, Al and Li). The suppression of GBS was associated with low grain boundary energy, and the extent to which the energy is reduced depended on the alloying element. It was suggested that the change in the lattice parameter (the so-called c/a ratio) affects the grain boundary energy, and thus, the occurrence of GBS.