Empirical information on the acidity of the propargylic proton from our previous work allowed us to develop novel synthetic transformations of readily available terminally trifluoromethylated propargylic alcohols 1 into the corresponding allenyl tosylates 3a, 1-tosyloxy- or 1-acyloxy-4,4,4-trifluorobutan-2-ones 4, and 2-(2,2,2-trifluoroethyl)prop-2-en-1-ones 5, which was enabled by such common bases as NaOH and tertiary amines for affecting ready abstraction of this proton. 相似文献
The heat capacity of PbMO3 (M=Ti, Zr and Hf) at constant pressure was measured using a differential scanning calorimeter (DSC) from room temperature up
to 870 K. Large anomalies were found in the heat capacity curves, corresponding to the ferroelectricparaelectric phase transition
in PbTiO3 (PT), the antiferroelectric-paraelectric phase transitions in PbZrO3 (PZ) and PbHfO3 (PH). The transition entropies were estimated as 7.3 J K−1 mol−1 (PT), 9.9 J K−1 mol−1 (PZ) and 9.3 J K−1 mol−1 (PH). These values of transition entropies are much larger than that of a typical displacive-type phase transition. 相似文献
Plug and play : Photoinduced electron transfer occurs from photoexcited P700 in photosystem I (PSI) to a gold surface (see picture). A novel molecular connector system is used, in which an artificial molecular wire, which is assembled on the gold surface, was plugged into PSI by reconstitution. Analysis of the photoelectron transfer kinetics proved both the output of electrons from PSI and the effectiveness of the molecular wire.
In this paper, we investigate relations between constraint qualifications in quasiconvex programming. At first, we show a necessary and sufficient condition for the closed cone constraint qualification for quasiconvex programming (Q-CCCQ), and investigate some sufficient conditions for the Q-CCCQ. Also, we consider a relation between the Q-CCCQ and the basic constraint qualification for quasiconvex programming (Q-BCQ) and we compare the Q-BCQ with some constraint qualifications. 相似文献
A certified reference material, NMIJ CRM 7405-a, for the determination of trace elements and As(V) in algae was developed
from the edible marine hijiki (Hizikia fusiforme) and certified by the National Metrology Institute of Japan (NMIJ), the National Institute of Advanced Industrial Science
and Technology (AIST). Hijiki was collected from the Pacific coast in the Kanto area of Japan, and was washed, dried, powdered,
and homogenized. The hijiki powder was placed in 400 bottles (ca. 20 g each). The concentrations of 18 trace elements and
As(V) were determined by two to four independent analytical techniques, including (ID)ICP-(HR)MS, ICP-OES, GFAAS, and HPLC-ICP-MS
using calibration solutions prepared from the elemental standard solution of Japan calibration service system (JCSS) and the
NMIJ CRM As(V) solution, and whose concentrations are certified and SI traceable. The uncertainties of all the measurements
and preparation procedures were evaluated. The values of 18 trace elements and As(V) in the CRM were certified with uncertainty
(k = 2). 相似文献
The synthesis of nucleoside analogues with a conformationally restricted sugar moiety is of great interest. The present research describes the synthesis of BNA (bridged nucleic acid) monomers 1 and 2 bearing a 4,7-dioxabicyclo[4.3.0]nonane skeleton and a methoxy group at the C2' position. Conformational analysis showed that the sugar moiety of these monomers is restricted in a typical S-type conformation. It was difficult to synthesize the phosphoramidite derivative of the ribo-type monomer 1, while the phosphoramidite of the arabino-type monomer 2 was successfully prepared and incorporated into oligodeoxynucleotides (ODNs). The hybridization ability of the obtained ODN derivatives containing 2 with complementary strands was evaluated by melting temperature (T(m)) measurements. As a result, the ODN derivatives hybridized with DNA and RNA complements in a sequence-selective manner, though the stability of the duplexes was lower than that of the corresponding natural DNA/DNA or DNA/RNA duplex. 相似文献
In this study, we experimentally obtained partitioning ratios of radioiodide (125I?) in the three phases at two different temperatures, 4 and 23 °C, in order to observe the effect of biological activity for upland soil samples. Even at 4 °C, 125I emission was found; its partitioning ratio in the gas phase ranged from 0 to 27 %. As expected, the ratio at 23 °C was higher than that at 4 °C. Additionally, in comparison of the data for upland soil samples obtained in this study and our previous data for paddy soil samples, for the latter, I? was not only sorbed in the soil but also more of it was released into the air than for upland soil samples. The land-use difference for I? partitioning in soil might be attributed to the differences of exchangeable K and stable I concentrations in soil from the statistical analysis. On the other hand, there were good correlations of partitioning ratios in solid, liquid, and gas phases between the two temperatures. The results implied that the biological activity can enhance partitioning in not only the gas phase, but also the solid phase. Indeed, the soil–soil solution distribution coefficient at 23 °C was about three times as high as that at 4 °C. 相似文献