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1.
The glass transition temperature (Tg), measured by Modulated Differential Scanning Calorimetry (MDSC), is related to the flow characteristics of asphalt at low temperatures as is the rate of change of the creep stiffnessm. This study compared the glass transition temperature of different asphalts (neat, chemically modified, and crumb rubber modified asphalts) with the creep stiffness, the rate of change of creep stiffness, and the low specification temperature of the continuous PG grading of those asphalts.From the rheological data (BBR) and the thermal data (MDSC) for the virgin and the modified asphalts, the modified products had the same variations of values ofm, S, and Tg at lower temperatures as those of their corresponding virgin asphalts. A correlation between the Tg andm value was observed for both the modified and unmodified asphalts. Since DSC measurements for asphalt low temperature properties use less operator time, less sample, and have less measurement and operator error than rheological methods, Tg has promise to be considered as a fast and easy laboratory method to obtain the low temperature useful range of asphalts in pavements.The authors would like to acknowledge Susan P. Needham for her work in conducting rheological testing for the modified and unmodified asphalts. 相似文献
2.
Raman spectra of a series of alkali-halide/BH?4 (and BD?4 crystals have been obtained. These spectra show some interesting examples of Fermi resonance type interactions between the stretching mode levels and overtone and combination band levels of the bending modes. Two resonances will be considered: (i) that between ν1 and 2ν4(A1), and (ii) that between ν3, 2ν4 (F2) and (ν2+ν4) (F2).The F2 resonance between ν3, 2ν4 and ν2+ν4 appears in the infrared spectrum and it has been studied on several occasions. However the equivalent Raman spectrum is of interest because the relative intensities of the bands are significantly different to those shown by the infrared spectrum.In the A1 (and E) Raman spectrum of the stretching mode region there are two strong bands for each for the 10B and 11B isotopes. The ν1 would not be expected to show any 10B and 11B splitting, but the observed bands are both closely resonating mixtures of ν1 and 2ν4(A1). In fact the analysis shows that the stronger band has the higher proportion of 2ν4 character, and the larger isotopic shift of the more intense band can then be seen to be reasonable. 相似文献
3.
The use of microemulsion in flow-injection systems is considered, with particular reference to the determination of C6C10 primary amines by derivatization with o-phthal-aldehyde and 2-mercaptoethanol. Microemulsions provide an ideal interface for reactions between a water-soluble reagent and a non-aqueous sample. The effect of reaction conditions (R value, droplet concentration, pH and flow rate) on the fluorescence signal is discussed and calibration data for three primary alkylamines are given. 相似文献
4.
The article describes the synthesis and extraction properties of a new chiral calix[4]arene Schiff base ligand 5, which has been synthesized from 5,17-diformyl-25,27-bis-(4-nitrobenzyloxy)-26,28-dihidroxycalix[4]arene (4) by treatment with (S)-(-)-1-phenylethylamine. In this synthesis, it was thought to explore the role of chiral, as well as Schiff base sites in the recognition of targeted species ions (such as dichromate anions) as well as neutral/chiral molecules. At low pH, the ligand 5 is more effective for transferring the dichromate anions from an aqueous into a dichloromethane layer; may be due to the protonation of nitrogen atoms. The extraction properties of ligand 5 towards the some selected α -amino acid methylesters are also reported. However, the ligand 5 did not display any selectivity towards the selected α-amino acid methylesters. 相似文献
5.
The article describes the syntheses and extraction properties of two p‐tert‐butylcalix[6]arene nitrile derivatives (3 and 4). The trinitrile derivative 3 has been synthesized from 5,11,17,23,29,35‐hexa‐tert‐butyl‐37,38,39,40,41,42‐hexahydroxycalix[6]arene 1. The compound 1 was directly converted to its hexanitrile derivative 4. In these syntheses, it was thought to explore the role of nitrile sites in the extraction of various metal cations and HCr2O7 ?/Cr2O7 2? anions. The liquid‐liquid extraction properties of 3 and 4 towards selected alkali/transition metal cations and HCr2O7 ?/Cr2O7 2? anions are reported. It has been observed that receptor 3 does not extract alkali/transition metal cations effectively, but shows affinity towards HCr2O7 ?/Cr2O7 2? anions at low pH. The compound 4 is an effective form for transferring Ni2+ selectively, while it shows poor transferring ability for HCr2O7 ?/Cr2O7 2? anions from an aqueous into a dichloromethane layer. It was observed that the cavity size of the calix[n]arenes and the cooperativity of the functionalities play important roles in two phase extraction systems. 相似文献
6.
A novel chiral calix[4](azoxa)crown-7 (9) has been synthesized and its metal ion recognition properties investigated. The starting reagents, chiral diamine 5 and calix[4]arene diacid chloride derivative 8, were prepared according to literature methods. 1H and 13C NMR data show that 9 exists in a cone conformation. In liquid–liquid extraction experiments, 9 exhibits selectivity for Li+ among the other alkali metals and a good extraction ability for transition metal cations, suggesting its potential use in different fields, such as a sensor for ions as well as for chiral molecules. 相似文献
7.
Six fish species-Cirrhinus mrigala (Morakhi), Labeo rohita (Danbhro), Catla catla (Thalli), Wallago attu (Jarko), Ctenopharyngodon idella (Grass), and Cyprimus carpio (Gulfam)--commonly found in the Pakistani Indus river, were selected for fat and cholesterol evaluation. Fat content was quantified by the Folch method and cholesterol content was determined by a simple GC method. The application of the proposed method to quantify cholesterol content revealed variations among the six breeds evaluated. The breeds studied contained 0.80-1.95% fat, indicating that all investigated fishes were lean; significant variation was found in cholesterol content, and ranged between 72 and 392 mg/100 g. Standard addition analyses showed that the method was accurate, as the recovery of cholesterol varied from 95 to 103%, with a coefficient of variance not more than 5.6%. The results showed that, after the development of suitable calibration, within 11 min, the cholesterol could be accurately determined by GC. 相似文献
8.
A.A. Pilt J.A. Kuehner Ren-cheng Shang M.A.M. Shahabuddin A. Trudel 《Physics letters. [Part B]》1981,100(2):114-116
We point out that, in many cases, anti-analogue 0+ states cannot be populated in )d, α) reactions. This results from the particular isospin structure of the anti-analogue, and may well be new, useful, tool to aid in the identification of such states. A particular example arising in the 42 Ca (d, α) reaction is generalized in a straightforward way. 相似文献
9.
The 3He scattering cross sections have been measured at 17.5 and 40.0 MeV from the ground state and first four excited levels of 11B. The results are analysed with the SCA assuming 11B to be a symmetric rotator and including the K-band mixing introduced by the Coriolis force. A systematic attempt is made to deduce the hexadecapole moment and the sign of the quadrupole deformation of 11B. 相似文献
10.
Mansoor Ahmed Qazi Ümmühan Ocak Miraç Ocak Shahabuddin Memon Imam Bakhsh Solangi 《Journal of fluorescence》2013,23(3):575-590
A readily available chromionophore 5,11,17,23-tetra-tert-butyl-25,27-bis(hydrazidecarbonylmethoxy)-26,28-dihydroxycalix[4]arene (HCC4) was employed as a chromogenic sensing probe selective for Pb(II) and Cr2O7 2? ions among a series of various ions such as Li(I), Na(I), K(I), Rb(I), Ba(II), Sr(II), Al(III), Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) as well as Cr2O7 2?, CH3CO2 ?, Br?, Cl?, F?, I?, ClO4 ? and NO3 ? that have been examined by UV-visible and fluorescence spectroscopic techniques. The HCC4 in DCM-MeCN system forms 2:1 (ligand-metal) complex with Pb(II). It also shows 2:1 stoichiometry with Cr2O7 2?. The complexation phenomenon has been confirmed by FTIR spectroscopy that favors the selective nature of HCC4 with Pb(II) and Cr2O7 2?. Thermal gravimetric analysis (TGA) also supports its utility in drastic conditions. 相似文献