, S. P. , Zhou , P. and Yu , D. S. , Ultimate generalization for monotonicity for uniform convergence of trigonometric series , arXiv: math.CA/0611805 v1 November 27, 2006 , preprint; Science China , 53 ( 2010 ), 1853 – 1862
A copper, zinc and aluminium mixed oxides sample having the nominal composition 0.25 CuO/0.03 ZnO/Al2O3 was prepared by impregnating Al(OH)3 with copper and zinc nitrate solutions, drying at 100 °C then heating in air at 600 °C. The obtained solid was exposed to different doses of -rays (20–160 Mrad). The surface characteristics namelySBETVP andr of different treated adsorbents were determined from N2 adsorption isothems measured at –196 °C. The catalytic activity of various irradiated solids was determined by following up the kinetics of CO-oxidation by O2 at 150–200 °C. The results showed that the doses up to 80 Mrad resulted in no significant change in theSBET but increased slightly theVP (20%) of the treated adsorbents. The irradiation at 160 Mrad caused an increase of 20% in theSBET of the irradiated solid sample. The catalytic activity increased progressively by increasing the dose, a dose of 160 Mrad brought about an increase of 140% in the catalyst's activity. The apparent activation energy of the catalytic reaction decreased monotonically by increasing the absorbed dose of -rays which was attributed to a parallel induced decrease in the value of pre-exponential term of the Arrhenius equation. The observed increase in the catalytic activity due to -irradiation has been interpreted as a result of increasing the concentration of catalytically-active sites contributing in chemisorption and catalysis of CO-oxidation via a possible fragmentation of CuO crystallites.
The instantaneous elastic moduli for a nylon-6 monofilament were derived on strain recoveries right after creep, stress relaxation, and rapid elongation,Ec,Es andEe, respectively. It was found that during strain recoveryEs(>Ee) andEe increase monotonically with increasing load,m1, on the sample. The extrapolated value of Es atm1=0 g is almost equal to Young's modulus, 4.06 GPa. The value ofEc also increased with increasingm1, and atm1=600 g (1.93 t cm−2) reached about 14 GPa. The endothermic heat change right after creep, stress relaxation or rapid elongation,Q, was negligibly small. For comparison,Es,Ec andQ were also investigated for silicone rubber. It was found thatEs (53.8 M Pa at the draw ratioD=1.2) decreased abruptly atD=1.3. In the range ofD=1.4–1.9,Es was only 22.6 MPa. In the case of stress relaxation,Q increased with increasingD from 4 J mol−1 (atD=1.2) to 56 J mol−1 (atD=1.9). FurthermoreEc (5.58 MPa atm1=133.8 g (429.4 kg cm−2)) increased gradually with increasing m1 and attained 16.6 MPa atm1=548.4 g (1.76 t cm−2). In the case of creep,Q was in the range of 0–11.5 J mol−1 and larger when larger loads,m2 were removed during the later stages of creep.
Flow birefringence (FB) has been investigated in solutions of products of hydrolytic degradation of poly(naphthoyleneimide
benzimidazole) (PNIB) in 96% sulphuric acid PNIB solutions have previously been subjected to heating at various temperatures
from 65 to 120°C and then investigated at 22°C by FB and viscometry. A monotonic decrease in intrinsic viscosity and the molecular
weightM of thermal degradation products with increasing degradation temperature was detected. At the same time, the shear optical
coefficients in series of products with decreasingM first increases and then, at treatment temperatures exceeding 90°C, decreases with decreasing [ν] in accordance with decreasingM of the product. Possible reasons for the detected anomaly have been discussed.
, has been studied by the method of statistical thermal analysis (STA). It is shown that the melting temperature of solid
phase (Tm) increases non-monotonic from 970 °C due to rise in the preliminary melt overheating, and Tm reaches asymptotically 1010 °C. The equilibrium melting-crystallization temperature (
) has been defined as 989.2 °C. It is also found an extreme dependence of the melt supercooling on its overheating. The two
curves of irregular dependence of nucleation rate on melt supercooling have been plotted at different melt overheating.
Authors:R. De Lisi, G. Lazzara, S. Milioto, and N. Muratore
Macromolecule/laponite nanomaterials were
studied by DSC and X-ray diffraction techniques. The matrices are poly(ethylene)
glycols at various molecular masses and poly(ethylene oxides)-poly(propylene
oxides)-poly(ethylene oxides) tri-block copolymers. The latter were tuned
by modulating the molecular masses, at constant hydrophilic/hydrophobic ratio,
and the hydrophilicity. For all the investigated systems, the enthalpy of
is nearly constant up to a given composition thereafter it increases monotonically
reaching the value of the pure macromolecule. We proposed a model to interpret
the DSC data.
Briefly, it was invoked a mechanism of interaction
following which some segments of the adsorbed macromolecule are anchored to
the laponite (RD) particles and the remaining segments are radiating away
from the surface. The portion of the macromolecule in contact with RD does
not contribute to ΔHm
whereas that radiating away from the clay does. Once that the RD surface is
saturated, the excess of the macromolecule behaves like the pure one. The
proposed model allowed to compute successfully the ΔHm
values. The X-ray diffraction experiments ruled out the polymer intercalation
between the silicate sheets.