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Fast field cycling, FFC, NMR relaxometry experiments are reported in the frequency range of 10 kHz to 40 MHz to characterize the molecular dynamics of a series of protic (methanol and water) and aprotic (dimethyl sulfoxide, acetone, cyclohexane, and n-heptane) adsorbates on a γ-alumina surface of catalytic interest. By analyzing the data in the T1domain, two distinct peaks were observed for both methanol and acetone. In the case of methanol, the two peaks have been shown to originate from the two chemical environments of methanol, which at low field strengths differentiate the O1H and alkyl 1H interactions with the surface. In contrast, the second environment of adsorbed acetone is assigned to a stable reaction intermediate formed during an aldol reaction, which strongly influences other molecular adsorption processes at the surface. Inversion of the FFC-NMR data into the T1-domain enables the combination of the ability of low field NMR to characterize relaxation modes directly associated with adsorption with T1measurements specific to functional groups and reaction intermediates, thereby avoiding misinterpretation of molecular adsorption characteristics and giving greater insight into adsorption and catalytic behavior than is possible from the overall relaxation dispersion profiles alone.

Natural and manufactured disordered systems are ubiquitous and often involve hierarchical structures. This structural organization optimizes defined physical properties at several scales from molecular to representative volumes where the usual homogenization approach becomes efficient. For studying a particular physical property on these systems it is thus required to use a general method of analysis based on the joint application of complementary techniques covering the whole set of time-and length-scales. Here we review a comprehensive multiscale method presented for analyzing the three-dimensional moisture transport in hierarchical porous media such as synthesized reference silicates and cement-based materials. Several techniques (NMR spectroscopy, relaxometry, diffusometry, X-ray micro-tomography, conductivity…) have been used to evidence the interplay between the different scales involved in this transport process. This method allows answering the general opened questions concerning the scale dependence of such a moisture transport in cement-based materials. We outline the main results of the multiscale techniques applied on reference porous silicates allowing separating the impact of geometry, hydric state and wettability on the moisture transport. Based on this approach, we prove that this transport at micro- and meso-scale is determinant to modify the moisture at macro-scale during setting or for hardened cement-based materials.

Natural and manufactured disordered systems are ubiquitous and often involve hierarchical structures. This structural organization optimizes defined physical properties at several scales from molecular to representative volumes where the usual homogenization approach becomes efficient. For studying a particular physical property on these systems it is thus required to use a general method of analysis based on the joint application of complementary techniques covering the whole set of time-and length-scales. Here we review a comprehensive multiscale method presented for analyzing the three-dimensional moisture transport in hierarchical porous media such as synthesized reference silicates and cement-based materials. Several techniques (NMR spectroscopy, relaxometry, diffusometry, X-ray micro-tomography, conductivity…) have been used to evidence the interplay between the different scales involved in this transport process. This method allows answering the general opened questions concerning the scale dependence of such a moisture transport in cement-based materials. We outline the main results of the multiscale techniques applied on reference porous silicates allowing separating the impact of geometry, hydric state and wettability on the moisture transport. Based on this approach, we prove that this transport at micro- and meso-scale is determinant to modify the moisture at macro-scale during setting or for hardened cement-based materials.

The scarab beetle fauna (Coleoptera Scarabaeoidea) on Spotted Hyaena, Crocuta crocuta(Erxleben 1777), scats was investigated to identify the feeding guilds of scarabs on an unusual dung substrate. During 19 months inspecting hyaena latrines and surrounding roads, 69 specimens of 8 species of Scarabaeoidea (Trogidae and Scarabaeidae) were collected from 200 hyaena faeces samples and 17 samples of regurgitated hairs. With increasing amount of hairs in the samples, attraction to hyaena faeces increased (from dry, white faeces to soft, brownish faeces to regurgitated hairs). Most of the scarab species that we found feed generally on carrion and omnivore/carnivore dung. Three species have not previously been found on carrion but are likely to be (facultative) necrophages. Further records of beetles from hyaena faeces indicate that almost all species that are attracted by this bait are at least facultatively necrophagous. The dung part of their diet consists mainly of omnivore or carnivore faeces as is usual for necro-coprophagous species.

Summary Regulation of soldier development in termites at the endocrinological and social scale was intensively studied in the 60s and 70s, but conclusive results are still scanty. In termites, the presence of soldiers inhibits further soldier differentiation, but the mechanism is not well understood. Secretions from the frontal glands seem to be important, but dry- and dampwood termites do not have frontal glands. We investigated the influence of precocene I, a JH-antagonist, and of soldier head extracts on the development of soldiers in the drywood termite, Cryptotermes secundus (Hill). Soldierless colonies produced fewer soldiers when treated with precocene I or soldier head extract than control colonies. Furthermore, colonies treated with precocene I had produced worker-nymph intercastes, last stage nymphs and alates by the end of the experiment (after six months) which were not present in control colonies. Hence, both treatments inhibited soldier development while precocene I simultaneously promoted the development of adult traits, probably by reducing (directly or indirectly) the JH level. The inhibition effect of the soldier head extract indicates that at least in termites without a frontal gland, other sources of material in the head have a regulatory function.

In northern Australia, compass termites build tall wedge-shaped mounds with an elongated axis that has a striking north-south orientation. Various hypotheses have been advanced to account for this remarkable mound architecture. However, behavioural aspects of mound orientation have rarely been investigated. The currently accepted hypothesis considers mound orientation as an adaptation to local long-term environmental conditions to maintain a temperature plateau at the eastern face of the mound. According to this hypothesis termites should concentrate at the eastern face when ambient temperature conditions are not ideal. This was tested in the current study by applying a new, non-destructive technique that allows monitoring of termites through solid material. Termatrac®, a tool developed for termite pest detection, uses microwaves to detect the movement of termites. As predicted by the eastern- face-plateau hypothesis, termites concentrated in the morning at the eastern face of the mound. However, this pattern was not found at sunrise or noon despite a similar temperature gradient between eastern and western face. This might indicate that only the morning heating of the eastern face is important for the termites, while it plays no prominent role during the rest of the day. The eastern-face-plateau hypothesis is then compared with other hypotheses to develop a general framework that addresses the different characteristics of compass mound architecture: shape, orientation and geographic variation in orientation.

We present nuclear spin-relaxation experiments, at various temperatures and Larmor frequencies for water and oil confined in a series of calibrated porous media and various natural rocks. The temperature and frequency dependencies of the longitudinal nuclear spin relaxation rates 1/T1 are interpreted with an original model of surface diffusion taking into account the solid−liquid interactions with the pore surface. Depending of the strength of such interactions, one observes an anomalous temperature dependence of the transverse 1/T2 and longitudinal 1/T1 nuclear spin-relaxation rates for water in silica and various sandstones and a normal temperature behavior for water-saturated calcium carbonate surfaces. The model supports also the normal temperature dependence observed for oil saturated porous media at proximity of silica, sandstone, and carbonate surfaces. The potential impact of this study for NMR well logging applications is also discussed.

Summary. Few studies have investigated foraging decisions in collectively foraging social insects with no studies in termites. In termites predation is assumed to be a key mortality factor. Therefore, we experimentally investigated the role of predation pressure in foraging decisions of the fungus cultivating, mound building termite Macrotermes bellicosus in two habitats of the Comoé National Park (Ivory Coast). We used the indirect approach of measuring the Giving up Density (GUD), which is the amount of food left when individuals stop foraging in a food patch, whilst experimentally varying predation pressure. Three different conditions were examined: (a) natural predation, (b) no predation, and (c) experimental predation through artificial removal of termites. In the shrub savanna, foraging termites responded to increasing predation with increasing GUDs. By contrast, in the gallery forest, there was no gradual response. Instead termites abandoned a food patch immediately after an attack by predators. Without predation GUDs were lower in the savanna than in the gallery forest indicating that food had a higher value in the former habitat. This, together with the differential behavioral responses to predation, was in accordance with high availability of food in the gallery forest and a limited supply of food in the savanna. Thus, according to our results termites traded off predation pressure differently, according to the availability of food in both habitats.

Nuclear magnetic resonance measurements of ¹²⁹Xe chemical shifts in a large variety of nonionic calibrated microporous and mesoporous silica glasses with open porosity provide a calibration of spectroscopic mesopore size measurements. The pore size dependence of the xenon chemical shift is quantitatively interpreted by considering both fast exchange and van der Waals interactions at the surface, which cause chemical shifts. The temperature dependence of the chemical shift supports the proposed model and characterizes the enthalpy of adsorption at the pore surface. The xenon NMR measurement is also useful for very low or even quasi-closed porous systems and may provide assessment of the macroscopic xenon diffusion coefficient in xerogels.

In the past it has been demonstrated that the carbon concentration of large semi‐insulating (SI) GaAs single crystals grown by the conventional liquid encapsulation Czochralski (LEC) technique can be controlled by several methods including variations of growth parameters. It was the aim of the present paper to clarify which of the relationships of LEC growth could be used for a carbon control in the VCz‐method characterized by the application of an inner chamber made from graphite to avoid selective As evaporation. In detail this comprised a study of the influence of several growth parameters like the water content of the boric oxide, the composition of the working atmosphere, the gas flow, a titanium gettering and additions of gallium oxide. As a result, for the first time carbon concentrations down to ≈ 1014 cm‐3were obtained in 3'' (75 mm) diameter VCz crystals.

Spin−lattice relaxation times of individual carbons in 2-ethylhexyl benzoate (EHB) in bulk and confined to porous silica glasses of pore radii of 33, 52, and 102 Å were measured as a function of temperature from +40 to −51 °C. The two-state fast exchange model was successfully applied, in the wide temperature range including beyond the motional narrowing regime, to determine the spin−lattice relaxation times of the molecules in the surface layer (T1S) as a function of temperature. The Cole−Davidson distribution model was used to analyze the relaxation data for both the bulk (T1B) and surface layer (T1S) of the confined liquid. The line broadening of confined EHB at lower temperatures below −21 °C inherently limited the temperature range over which T1S could be estimated and prevented the quantitative analysis of T1S by the model. Through the phenomenological comparison of T1S with T1B in terms of the parameters of the Cole−Davidson model, it was found that the motional behavior of the phenyl ring part of the EHB molecule was significantly affected by the surface interaction and the effect is smaller for the flexible alkyl chain. Small temperature dependence of the relaxation rate of T1S at motional narrowing regime showed a characteristic feature of liquid diffusing on a two-dimensional surface. In addition, the results of the quantitative analysis of T1B were compared with a previous experiment performed as a function of pressure.

Summary Ribosomal RNA isolated from ribosomes present inside avian myeloblastosis virus (AMV) was characterized by electron microscopy using the formamide-urea spreading technique. The molecular weight and the secondary structures were compared with those of r-RNA and precursor r-RNA isolated from host cells, the leukemic myeloblasts. The molecular weight of viral r-RNA (1.62±0.18×106 and 0.69±0.10×106) and the molecular weight of cellular r-RNA (1.63±0.18×106 and 0.67±0.09×106), the latter obtained from avian myeloblasts, were found to be identical and comparable with the molecular weight of chicken liver r-RNA. Likewise, the secondary structures of viral r-RNA were identical to those of cellular r-RNA. The postulated possible precursor character of viral r-RNA was excluded, since the molecules of viral r-RNA do not show any similarity to those of precursor r-RNA. Previously observed differences in behavior of viral and cellular (myeloblastic) r-RNA in sedimentation and electrophoretic mobility are discussed.

Summary: Mounds of the fungus-cultivating termite Macrotermes bellicosus (Smeathman) in the Comoé-National Park (Ivory Coast, West Africa) differ in architecture between habitats. Mounds in the cooler, but thermally more stable gallery forest have been shown to be dome-shaped with thick walls, whereas mounds in the shrub savanna are more complex with many ridges and thin walls. In this investigation, we performed heating experiments to determine the thermal properties of the mounds in both habitats in order to test the hypothesis of a thermoregulatory significance of mound architecture. These experiments revealed that each mound had its characteristic individual heating up behavior that depends on its dimensions (height, surface, volume). In addition, habitat-specific traits were demonstrated: mounds of the gallery forest had higher thermal inertia, measured by the thermal capacity, than mounds of the shrub savanna. Thus, the dome-shaped mounds with thick walls in the gallery forest, with its suboptimal low temperatures, reduce loss of heat to the environment.

Summary: We determined density and distribution of the mounds of the fungus-cultivating termite Macrotermes bellicosus (Smeathman) in two habitats (shrub savanna and gallery forest) of the Comoé National Park (Ivory Coast, West Africa). We measured height, basal width, and interior and exterior temperatures of mounds in both habitats, and established a new method to measure the surface area of mounds.¶ In the shrub savanna, M. bellicosus mounds reached high densities (up to 22.7 live mounds/ha), whereas in the gallery forest mounds could only be found in open stands and at comparatively low densities (up to 6.5 live mounds/ha).¶ Ambient temperature had an important influence on the architecture of the mounds. Mounds in the warmer, but thermally more fluctuating shrub savanna were more structured with many ridges and turrets than the dome-like, compact mounds in the cooler, more equable gallery forest. The surface complexity was quantified as the ratio of surface (= rsf), which is the quotient of the real surface to the minimal possible surface of an ideal cone of the same height and basal width as the measured mound. By manipulating ambient temperatures, we were able to demonstrate causal relationships between temperature and mound shape. In the gallery forest, where shade was reduced surface complexity increased on mounds.¶Despite their different architecture in the gallery forest, the M. bellicosus colonies could not completely compensate for the cooler environment and had a lower than optimal nest temperature. We speculate that this might be caused by the need for a sufficient surface for gas exchange. The gallery forest is a suboptimal habitat for M. bellicosus, because of lower than optimal nest temperatures. This might limit M. bellicosus to open stands in the gallery forest and may explain its surprisingly low abundance in this habitat.

We have investigated the EPR spectral lines of the photo-excited triplet state of pyrene-d-10 both in a fluorene single crystal and an ethanol glass matrix. In the crystal we have measured the width, shape and saturation parameters, λ', a and B1/2u, of the ΔM = 1 lines from both sites in the cleavage plane, Y-Z, at 193 K and along the principal directions, X, Y, Z, between 143 K and 300 K. In the glass the same parameters have been measured for the six resonances of the absorption derivative at 77 K. We have used a general deconvolution procedure to extract the unresolved inhomogeneous and homogeneous broadenings, ΔBG and ΔBL ≡ 1/γT2, and the spin-lattice relaxation rate, T1-1, from λ', a and B1/2u for the different types of resonances. The use of Fourier-series expansions permits optimal utilization of the data and resolution of the terms of different symmetries for these quantities. The application of the method of moments, using assumed spin densities, permits the demonstration that the main contribution to the constant term of ΔBG, but only a small part of its anisotropy, originates from the intramolecular hyperfine interactions. As T2 and T1 are of the same order of magnitude, we have assumed the same mechanism, i.e. modulation of the fine-structure tensor D, for both relaxation effects. A first-order semi-classical treatment leads to partial agreement between the main features of the calculated and observed orientation dependences if one assumes strongly anisotropic librations coupled to large modulations of D. This is consistent with the maximal libration amplitudes estimated from the differences between the D tensors measured in the crystal and in the glass. Variations with temperature are attributed to a competition between the increase of modulation amplitudes and decrease of correlation time with heating.

Lamellar phases of double tailed sodium alkyl-phosphates/water systems have been investigated by 31P and 13C relaxations enhanced by paramagnetic divalent ions exchanging rapidly among the polar heads of the surfactant molecules. In order to extract both structural and dynamic information from these experiments, the paramagnetic probes have been chosen such that their electron spin-lattice relaxation times are significantly larger (Mn2+, VO2+) or smaller (Ni2+) than the time scales of molecular motions generally found in the 0.1-2.0 ns range. The paramagnetic relaxation of surfactant nuclei results from intra- and intermolecular contributions, the latter corresponding to dipolar interactions in a two dimensional lattice. The sum of these contributions has been computed as an average over all accessible conformers resulting from the trans-gauche isomerizations of alkyl chains and fitted to the experimental relaxation rates at several magnetic field strengths. This procedure allows the determination of the populations of the main conformers, of the reorientational correlation times and of the lateral diffusion coefficient of the surfactant, which are sometimes difficult to obtain by other N.M.R. methods.

The N.M.R. relaxation times of liquids in heterogeneous systems, where a molecule is either close to an interface, or has diffusive motions which are in some way geometrically bounded, often show features such as spin-lattice relaxation time (T1) minima resembling those found in bulk solids. These measurements have nearly always been interpreted using the theory of relaxation for bulk materials. This frequently leads to the conclusion that there is, as a result of proximity to the interface, a reduction in the molecular mobility of several orders of magnitude compared to the bulk liquid. This conclusion often conflicts with those derived from other measurements such as quasielastic neutron scattering. Another interpretation which takes into account the restricted nature of the diffusion is given. The effects that bounded two dimensional motion has on proton relaxation times are discussed in detail and the theory applied to a number of real cases. Calculations using the diffusion constants determined by neutron scattering give values of T1 and T1 minima in agreement with experiment. In our opinion these results place a doubt on the correctness of the conclusions of the majority of proton N.M.R. relaxation time measurements in heterogeneous systems.

Molecular weight determinations of native and subunit RNAs of murine mammary tumor virus (MuMTV), a type B oncornavirus, were performed by polyacrylamide gel electrophoresis and compared with molecular weights of well-characterized avian cellular RNAs and tobacco mosaic virus RNA. From extrapolations of semilog plots of the molecular weights of the standard RNAs versus relative electrophoretic mobilities and Ferguson plots, the subunit and native RNAs of MuMTV were found to possess molecular weights of 2.93 X 10(6) and 6.45 X 10(6), respectively. These data support the assumption that two subunit molecules comprise the native RNA of MuMTV.

The three species of single-stranded RNA present in La Crosse virus were examined in the electron microscope. Because large amounts of contaminating cellular DNA are copurified with the virus despite extensive attempts to purify the virus, it was necessary to use procedures that eliminated the bulk of this DNA before the viral RNA was analyzed. When this was done, the modal lengths of La Crosse virus RNA were 0.4, 2.0, and 3.1 mum. These lengths correspond well to their known molecular weights of 0.4 x 106, 1.8 x 106, and 2.9 x 106. Under the denaturing conditions used to permit complete spreading of these single-stranded RNA molecules, no single-stranded circular molecules are observed. Therefore, the circular nucleocapsids present in La Crosse virus and some other bunyaviruses do not appear to be due to convalent linkage of the ends of the RNA genome.

In the Guinea Savanna Zone of the Ivory Coast (Côte d'Ivoire) the dragonfly Crocothemis divisaKarsch 1898 survives the dry season as sexually inactive adults. Both sexes use mounds of the termite Macrotermes bellicosus(Smeathman 1781) as daytime resting sites. Individuals were often observed to aggregate on a few particular mounds, while the majority of mounds remained unoccupied. The insects, which perch in the shade on the ribs of the steep mound sides, repeatedly change their positions during the course of the day in response to direct solar illumination. Flights are very short and not accompanied by the aggressive behaviour typical of sexually active individuals. The choice of termite mounds is compared with this species' known preference for bare perches and is considered to be of importance for thermoregulation and to reduce the risk of predation.

The Kalotermitidae is a family of lower termites and its species are ideal to study the evolution and maintenance of eusociality within the Isoptera. Co-dominant genetic markers are an essential tool to elucidate the putatively complex colony and population structure. Six polymorphic microsatellite loci were identified in the drywood termite Cryptotermes secundus (Kalotermitidae). To test the variability of the markers, 18 colonies (n = 18) from Darwin (Australia) were assayed. We found two to eight alleles per locus with the level of observed heterozygosity at each locus ranging from 0.00 to 0.53. The significantly positive FIT value suggests that some kind of inbreeding does occur in this population.