). Regarding adrenoceptor modulation of ureteral smooth muscle function, β-adrenoceptors have been identified within the muscle, which have an attenuating influence upon ureteral contractile function ( 6 , 25 ). In addition, α-adrenoceptors have been
The TG(DTG) and DTA of poly(p-xylylene) and poly(α,α,α′,α′-tetrafluoro-p-xylylene) are reported. The degradation was performed from ambient temperature to 900°C in both air and nitrogen. Both polymer
degrade faster in air than under nitrogen but the fluorinated polymer eventually decomposed at higher temperature in air than
in nitrogen atmosphere. The activation energies of the degradation processes is given.
The thermal decomposition of poly(α,α,α′,α′-tetrafluoro-p-xylylene) (parylene AF-4) films with thicknesses of ca. 7.5 and 10 μm has been studied by both dynamic (10°C min−1) and isothermal TG in either nitrogen or oxygen atmospheres.
In dynamic studies with nitrogen, gross decomposition occurs between 546.7±1.4 and 589.0±2.6°C, with 26.8±4.4% of the initial
mass remaining at 700°C. With oxygen as the purge gas, the onset of decomposition shifts slightly to 530.8±4.2°C. The end
of the transition at 587.4±2.6°C is within experimental error of the nitrogen value, but no polymer remains above 600°C.
Isothermal data were obtained at 10°C intervals from 420 to 490°C in nitrogen, and from 390 to 450°C in oxygen. Plots of log(Δ%wt/Δt)vs. T−1 are linear throughout the specified range for oxygen and from 420 to 470°C for nitrogen. The calculated activation energies
of (147±16) kJ mol−1 and (150±12) kJ mol−1 in N2 and O2, respectively, are equal within experimental error.
Authors:D. Zhu, R. He, W. Yu, C. Li, H. Cheng, B. Zhu, and J. Yan
of great importance for tumor angiogenesis as well as growth [ 1 ]. HIFs are heterodimeric basic helix-loop-helix (bHLH)/Per-ARNT-Sim (PAS) transcription factor complexes, and are composed of an oxygen-liable α-subunit (HIFα) and a constitutively
We study the concepts of α-I-continuity and α-I-openness in ideal topological spaces, and obtain several characterizations and some properties of these functions. Also,
we investigate its relationship with other types of functions.
The terpenes α-(+)-pinene, and α-(−)pinene have been radiolyzed at radiation doses of 150, 300 and 600 kGy. The radiolyzed
samples have been analyzed by FT-IR spectroscopy and polarimetry. Both α-(+)-, α-(−)-pinenes show a linear trend to radioracemization
as a function of the radiation dose administered ≈2.5·10−3 [α]D/kGy. The solvent fractionation and the liquid chromatographic analysis (HPLC) of the radiolyzed samples shows that both α-pinene
enantiomers produce ocimene and dipentene together with minor quantities of other products and a resin. The kinetics of α-pinene
decomposition under radiolytic conditions can be described by a pseudofirst order rate constant k∼5.3·10−7s−1 while the radiation chemical yield for the same reaction has a G = 5.0 molecules/100 eV, so that about 30% of the original α-pinene is converted into other products at 600 kGy.
Authors:Alfredo Román-Tejeda and Heriberto Pfeiffer
different electrical and optical applications, as well as for glass structural components [ 13 , 14 ]. Among the lithium borates, there are two LiBO 2 phases: the α-LiBO 2 and the γ-LiBO 2 . The α-LiBO 2 system has an anhydrous monoclinic phase that is