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  • Author or Editor: H. Feng x
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Recently food-grade microemulsions have been of increasing interest to researchers and exhibited great potential on their industrial applications. The microbiological and quality characteristics of NuoMiGao, a traditional Chinese steamed rice cake, affected by a prepared food-grade monolaurin-containing microemulsion have been evaluated in this study. Microbiological analysis indicated that 0.05% microemulsion was comparable to 0.01% sodium dehydroacetate, extending the shelf-life by two days. The quality analysis showed that the addition of the microemulsion effectively prevented the hardening phenomena in rice cake; the lightness and yellowness were fairly stable while redness increased slightly (P<0.05); the lowered pH value and the prevention of moisture drop in rice cake were in agreement with the microbiological analysis and hardness trends.

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KDNBF (potassium 4,6-dinitrobenzofuroxan) has been used as a primer explosive in igniters and detonators for many years. Considerable information about the sensitivity of KDNBF to various stimuli, such as impact, friction, shock and electrostatic charge, is known. However, the thermal sensitivity of KDNBF has been relatively unexplored. Hence, there is very little information available concerning the fundamental thermal properties of KDNBF. Therefore, as part of an extensive thermal hazard assessment, DSC, TG, accelerating rate calorimetry (ARC) and heat flux calorimetry (HFC) measurements have been undertaken on KDNBF. The results demonstrate that KDNBF decomposes via a multi-step exothermic process directly from the solid state. The decomposition process does not appear to depend on the nature of the atmosphere, except in the final stage of the TG decomposition in air, where remaining carbonaceous material is converted to CO2. The first stage of the decomposition is sufficiently rapid that ignition occurs if too large a sample is used. Dynamic and isothermal methods were used to obtain the kinetic parameters and a range of activation energies were obtained, depending on the experimental conditions. The kinetic results have been analyzed in terms of various solid state decomposition models.

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The refinement of unsaturated fatty acids (UFA) from Hippophae rhamnoides L. seed oil was carried out by molecular distillation (MD) using response surface methodology (RSM). A central composite rotate design was used in order to optimize the experimental parameters: distilling temperature and feed flow. The optimal MD conditions were determined and the quadratic response surfaces were drawn from the mathematical models. The results suggested that the distilling temperature and feed flow significantly affected both the UFA content and oil yield in the two models. The optimum conditions for refining UFA were: distilling temperature 107.5 °C and feed flow 1 ml min−1. Optimal values predicted by RSM for the UFA content and oil yield were 82.38% and 62.59%, respectively. Close agreement between experimental and predicted values was obtained.

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Cytomixis has been described in many plant species, but not in Thinopyrum . The present study reports spontaneous cytomixis during microsporogenesis in Thinopyrum intermedium (2n = 42), Thinopyrum ponticum (2n = 70), and their F 1 hybrids with wheat. Cytomixis frequently occurred in early prophase I but very rarely in meiosis II. The type of cytomixis that occurred most often was where chromatins migrate from one nucleus into an adjacent cel1. Migration from one nucleus into two or more cells or from two or more nuclei into one cel1 was also observed. After a donor cell transferred chromatin to a recipient cell, the recipient cell would sometimes pass the chromatin on to another cell. Migration did not necessarily occur between cells in the same stage. Cytomixis in Th. ponticum and its hybrids with wheat was more complex than that in Th. intermedium . The possible causes, cytological consequences and genetic significance of cytomixis are discussed.

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The displacement adsorption enthalpies (ΔH) of denatured α-Amylase (by 1.8 mol L−1 GuHCl) adsorbed onto a moderately hydrophobic surface (PEG-600, the end-group of polyethylene glycol) from solutions (x mol L−1 (NH4)2SO4, 0.05 mol L−1 KH2PO4, pH 7.0) at 298 K are determined by microcalorimeter. Further, entropies (ΔS), Gibbs free energies (ΔG) and the fractions of ΔH, ΔS, and ΔG for net adsorption of protein and net desorption of water are calculated in combination with adsorption isotherms of α-Amylase based on the stoichiometric displacement theory for adsorption (SDT-A) and its thermodynamics. It is found that the displacement adsorptions of denatured α-Amylase onto PEG-600 surface are exothermic and enthalpy driven processes, and the processes of protein adsorption are accompanied with the hydration by which hydrogen bond form between the adsorbed protein molecules favor formation of β-sheet and β-turn structures. The Fourier transformation infrared spectroscopy (FTIR) analysis shows that the contents of ordered secondary structures of adsorbed α-Amylase increase with surface coverages and salt concentrations increment.

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Both calorimetric determination of displacement adsorption enthalpies ΔH and measurement of adsorbed amounts of lysozyme (Lyz) denatured by 1.8 mol L−1 guanidine hydrochloride (GuHCl) on a moderately hydrophobic packings at 298 K, pH 7.0 and various salt concentrations were carried out. Based on the thermodynamics of stoichiometric displacement theory (SDT) the fractions of thermodynamic functions, which related to four subprocesses of denatured protein refolding on the surface, were calculated and thermodynamic analysis that which one of the subprocesses plays major role for contribution to the thermodynamic fractions was made in detail. The moderately hydrophobic surface can provide denatured Lyz energy and make it gain more conformation with surface coverage or salt concentration increment. The displacement adsorptions of denatured Lyz onto PEG-600 surface are exothermic, more structure-ordered and enthalpy driven processes.

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A Tian-Calvet heat flux calorimeter has been modified for use with high pressures in measurements of thermal hazards of materials. The system comprising a specially designed high pressure vessel and an associated manifold is described. With this system, comparative measurements using both standard and high pressure vessels can be made, different materials and/or liners can be used for the high pressure vessel and an assessment of the influence of the gaseous environment on thermal behaviour can be made. Calibration was carried out in the range 25 to 300C at different pressures and heating rates, using sapphire and the calibration results were verified with benzoic acid, both reference grade materials. With the new vessel, pressures up to about 70 MPa can be used or recorded during the thermal decomposition of energetic materials. The reproducibility of the baseline, as illustrated by standard error results, was about 0.02% compared with 0.13% for the standard vessel, over the entire temperature range. The corresponding results for the baseline of the pressure vessel at 5.5 MPa (in air and Ar) and in a calibration experiment with sapphire were 0.08%. Experimental data obtained for ammonium nitrate and 2,3-dimethyl-2,3-dinitrobutane in the standard and pressure vessels are compared and discussed. The effect of pressure and the nature of the gaseous environment (inert or oxidizing) on the results for these two materials will be described.

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Isopropylnitrate (IPN) is described as a detonable material used in propellants and explosives. While there is considerable information available on its sensitivity and compatibility with other materials, very little is known about its thermochemical properties. This paper will describe the results obtained from some DSC, heat flux calorimetry (HFC) and accelerating rate calorimetry (ARC) measurements. The ASTM DSC method using a hermetic aluminum pan having a lid with a laser-produced pin hole was used to determine the vapour pressure of IPN1. Results calculated from an Antoine equation are in substantial agreement with those determined from DSC measurements. From the latter measurements, the enthalpy of vaporization was determined to be 35.320.62 kJ mol−1. Attempts to determine vapour pressures above about 0.8 MPa resulted in significant decomposition of IPNg. The enthalpy change for decomposition in sealed glass systems was found to be -3.430.09 kJ g−1 and -3.850.03 kJ g−1, respectively from DSC and HFC measurements on IPN1 samples loaded in air. Slightly larger exotherms were observed for the HFC results in air than those in inert gas, suggesting some oxidation occurs. In contrast, no significant difference in the observed onset temperature of about 150C was observed for both the HFC and ARC results. From DSC measurements, an Arrhenius activation energy for decomposition of 1264 kJ mol−1 was found. These measurements were also conducted in sealed glass systems and decomposition appeared to proceed primarily from the liquid phase.

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The occupational health impact of atmospheric pollution on exposed workers at one iron and steel complex was studied by instrumental neutron activation analysis of workers' hair samples and medical examination. The experimental results indicate that there is a positive correlation between the high inhalation amounts of iron and other trace elements by the exposed workers and the symptom of their high blood pressure and hypoglycemia, which implies that the atmospheric environment polluted by iron and steel industry has an adverse health impact on the exposed workers. The measures to relieve and abate the occupational diseases caused by air-borne particulate matter should be taken

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In mammals, testis development is initiated by the expression of the sex-determining gene, SRY , where-as the genetic trigger for sex determination in birds remains unknown. In the present study, the expression of seven genes implicated in vertebrate sex determination and differentiation were studied in chicken embryonic gonads from day 4 to day 12 of incubation using reverse transcription and the polymerase chain reaction (RT-PCR). Results showed transcription of c Lhx9 , c GATA4 , c Vnn1 , c Ppt1 , c Brd3 were sexually dimorphic during chicken gonadal development, whereas c Eki2 , c Fog2 were expressed at similar levels in both sexes. Results of comparative studies between mammals and chickens show that vertebrate sex-determining pathways comprise both conserved and divergent elements: expression profiles of c GATA4 /c Fog2 and c Vnn1 are similar to those in mammals, while others appear some differences. Possible functions of these genes on chicken gonadal development were analyzed based on their expression profiles.

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