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The knowledge of human bone viscoelasticity is an important issue for defining semirigid calcified tissues implants. A very sensitive technique was used to investigate bone viscoelasticity: the thermally stimulated creep method. A study of demineralized human bone was performed to determine the molecular origin of bone viscoelasticity. The thermally stimulated creep spectra of bone and demineralized bone, at the hydrated state, present a similar shape with one main retardation mode located at −133 and −120°C, respectively. This mode is shifted toward higher temperatures after dehydration, revealing the existence of another mode at around −155°C. The analysis of elementary spectra of bone and demineralized bone has shown that retardation times follow an Arrhenius equation, and that two compensation phenomena are observed with comparable compensation parameters. The first compensation phenomenon, which corresponds to the main retardation mode, was attributed to motions of water molecules located inside the collagen triple helix. The second compensation phenomenon, which reveals the existence of another relaxation mode at higher temperatures, was assigned to movements of hydrophilic side chains bound to water molecules. As for the mode observed at around −155°C, it was associated with motions of aliphatic side chains. Overall, bone viscoelasticity originates from the organic matrix. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2527–2533, 2001

Differential scanning calorimetry (DSC) and thermally stimulated current (TSC) were used to characterize human-bone collagen. DSC glass-transition and denaturation temperatures of the collagen in a dehydrated state were 90 and 215 °C, respectively. By TSC, the main relaxation mode, labeled α and located around 90 °C, could be attributed to the dielectric manifestation of the glass transition. The corresponding molecular movements are cooperative with a compensation temperature close to the denaturation temperature. At low temperatures and in a hydrated state, a second mode labeled β2 was observed at −110 °C. Dehydration shifted this mode to higher temperatures, revealing a weak mode labeled γ at −150 °C. This γ mode was attributed to motions of aliphatic side chains. An analysis of low-temperature elementary spectra allowed us to assign the β2 mode to structural water movements and revealed an additional compensation phenomenon in the temperature range (−80 to −50 °C). Because the compensation temperature of this mode was close to the collagen glass-transition temperature, the corresponding mode β1 was attributed to polar side-chain motions, precursors of a collagen glass transition. Finally, around ambient temperature, three sharp peaks were attributed to hydrogen bonds breaking. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 987–992, 2000

Two thermal analysis techniques—Differential Scanning Calorimetry and Thermostimulated Current—have been used to characterize a mica/glass fiber-reinforced composite; the matrix is a novolac epoxy resin. The glass transition temperature of the composite as determined by DSC is 80°C. Below the glass transition temperature, two complex relaxation modes γ and β, respectively situated at −90 and −40°C, have been observed. The analysis of the fine structure shows that they are constituted of elementary processes characterized by relaxation times following compensation laws. Because the compensation temperature corresponding to the γ mode is located in the vicinity of the glass transition, it has been assigned to cooperative movements precursors of the glass transition. The mobile units might be the phenyl rings in the bisphenol A. Considering its dependence upon water content, the β mode has been related to the molecular mobility of bound water. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 135–139, 1997

Ketimines such as (III) are prepared in order to determine the degree of chirality transfer from the chiral auxiliary to the sulfur atom in the formation of the sulfoxides (IV) or to the α‐carbon atom in the reaction of the anion with MeI to yield (VII) (space group P1 with Z=2) and (VIII).

The dibenzo‐ (Ia) or dinaphthothiophenes (Ib) are cleaved with lithium and then sulfurized with disulfur dichloride (II) to form the fused 1,2‐dithiins (III).