Using the medium's parameters introduced by Koppel and Palm, correlation equations are derived, which describe the solvatochromic shift of the CO and NH stretching vibrations for acetophenone and pyrrole. The statistical properties of the equations are examined using data on a set of 37 solvents and it is proved that the influence of the nonspecific solvation cannot be described as a sum of the terms dependent on the medium's polarity and polarizability. 相似文献
The temperature dependence of the molar heat capacities of the tellurites Fe2(TeO3)3, Fe2TeO5 and Fe2Te4O11 were determined. By statistical manipulation of the values obtained, the parameters in the equations for the corresponding
compounds showing this dependence were determined using the least-squares method. These equations together with the standard
molar entropies were used to determine the thermodynamic functions Δ0TSm0, ΔTT,Hm0 and (Φm0 + Δ0T’Hm0 / T) for T’=298.15 K. 相似文献
The bulk polymerization at -24° of α-methylstyrene initiated by the alkali metals and the graphitides LiC12, KC24 and KC36 has been studied. The tacticities of polymers have been measured by [1H] NMR. The alkali metals give polymers having the same tacticity and the propagation of the stereoconfiguration is bernouillian; LiC12 yields more racemic diads while KC24 and KC36 yield more meso diads and show a penultimate effect. By measuring the growing of the thickness of KC24 flakes, it appears that the more sterically hindered a monomer the more slowly it penetrates into the graphitide. The copolymerizations at 25° of styrene with 1-1 diphenylethylene or 1–2 diphenylethylene (trans stilbene) (comonomer ratio 1/1) initiated by KC24 in tetrahydrofuran (THF), xylene (XL), decahydronaphthalene (decalin DL) and cyclohexane (CH) have been studied. The amount of styrene units in the copolymers depends on the nature of the solvent: it increases as the interaction solvent-graphitide decreases. All the results support the view that the polymerization proceeds between the graphite layers. 相似文献
Two efficient and diastereoselective procedures for the synthesis of (Z)‐6‐(2‐oxo‐1,2‐dihydro‐3H‐indol‐3‐ylidene)‐3,3a,9,9a‐tetrahydroimidazo[4,5‐e]thiazolo[3,2‐b]‐1,2,4‐triazin‐2,7(1H,6H)‐diones by aldol‐crotonic condensation of 1,3‐dimethyl‐3a,9a‐diphenyl‐3,3a,9,9a‐tetrahydroimidazo[4,5‐e]thiazolo[3,2‐b]‐1,2,4‐triazin‐2,7(1H,6H)‐dione with isatins under acidic or basic catalysis are reported. Isomerization in (Z)‐7‐(1‐allyl‐2‐oxo‐1,2‐dihydro‐3H‐indol‐3‐ylidene)‐1,3‐dimethyl‐3a,9a‐diphenyl‐1,3a,4,9a‐tetrahydroimidazo[4,5‐e]thiazolo[2,3‐c]‐1,2,4‐triazin‐2,8(3H,7H)‐dione was observed under basic conditions. 相似文献
Tellurites of CuTeO3 and HgTeO3 are synthesized and their specific molar heat capacities are experimentally determined for the first time. The tellurites discussed in the present paper are used for preparation of optical glasses with special properties for optoelectronics, nuclear and power industries. The tellurites synthesized are prepared for chemical analysis, differential thermal analysis and X-ray analysis. The use of the tellurites studied is related to knowing their thermodynamic properties like specific molar heat capacity (Cp,m), enthalpy \( \left( {\Delta_{{{\text {T}}^{\prime}}}^{\text{T}} H_{\text{m}}^{0} } \right), \) entropy \( \left( {\Delta_{{{\text {T}}^{\prime}}}^{\text{T}} S_{\text{m}}^{0} } \right) \) and Gibbs energy \( \left( { - \Delta_{{{\text {T}}^{\prime}}}^{\text{T}} G_{\text{m}}^{0} } \right) \). The temperature dependences of their molar heat capacities are determined using the least squares method. The thermodynamic properties are calculated: entropy, enthalpy and Gibbs function. 相似文献
Speaking engagements, serving as session chairs, and receiving awards at national meetings are essential stepping stones towards professional success for scientific researchers. Studies of gender parity in meetings of national scientific societies repeatedly uncover bias in speaker selection, engendering underrepresentation of women among featured presenters. To continue this dialogue, we analyzed membership data and annual conference programs of a large scientific society (>7000 members annually) in a male-rich (~70% males), technology-oriented STEM subfield. We detected a pronounced skew towards males among invited keynote lecturers, plenary speakers, and recipients of the society’s Senior Investigator award (15%, 13%, and 8% females, respectively). However, the proportion of females among Mid-Career and Young Investigator award recipients and oral session chairs resembled the current gender distribution of the general membership. Female members were more likely to present at the conferences and equally likely to apply and be accepted for oral presentations as their male counterparts. The gender of a session chair had no effect on the gender distribution of selected applicants. Interestingly, we identified several research subareas that were naturally enriched (i.e., not influenced by unequal selection of presenters) for either female or male participants, illustrating within a single subfield the gender divide along biology-technology line typical of all STEM disciplines. Two female-enriched topics experienced a rapid growth in popularity within the examined period, more than doubling the number of associated researchers. Collectively, these findings contribute to the contemporary discourse on gender in science and hopefully will propel positive changes within this and other societies.
Microarc oxidation of aluminum in borate and silicate-alkaline electrolytes in order to form porous ceramic coatings that can be used as catalyst supports was subjected to an integrated study. The advantages of the technological modes of microarc oxidation of aluminum were analyzed. A catalytically active nickel oxide was deposited into pores of a ceramic coating. 相似文献