The “modified chlorite structure” forms by the dehydroxylation of the interlayer octahedral sheet of magnesian chlorite at around 500°C and results in a structure with a basal spacing near 27 Â (Brindley and Chang 1974). This process involves drastic textural modifications as indicated by gas adsorption experiments which reveal the formation of structural micropores. Infrared spectroscopy as well as thermogravimetry and mass spectrometric analysis show that these micropores are filled with molecular atmospheric water, carbon dioxide, nitrogen, argon and hydrocarbons which condense once the samples cool down. A high temperature treatment is needed in order to release the different phases. A heterogeneous dehydroxylation mechanism is proposed in which micropores are formed in donor regions and magnesium and oxygen are concentrated in acceptor regions. This leads to a 27 Å structure with micropore zones and enriched interlayer oxide zones alternating along the z-axis of the mineral.

The swelling of some well-defined Mg-, Ca-, Sr- and Ba- homoionic montmorillonites was studied in the domain of water relative pressures lower than 0.95. This involves the expansion of the crystal lattice itself, commonly known as the “interlamellar expansion” or “inner crystalline swelling”. The initial freeze-dried clays were characterized by nitrogen adsorption-desorption volumetry and controlled transformation rate thermal analysis. The evolution of the structural and textural properties of these different clays at different stages of hydration and dehydration was investigated using water adsorption gravimetry, immersion microcalorimetry at different precoverage water vapor relative pressures and X-raydiffraction (XRD) under controlled humidity conditions. Large textural variations are observed in the dry state depending on the exchangeable cations. The 2-layer hydrate exhibits the most ordered layer stacking. Water is mainly adsorbed in the interlamellar space. With increasing water pressure, each homoionic species leads to a 1-layer hydrate and, with the exception of Ba-montmorillonite, to a predominant 2-layer hydrate. The relative pressure corresponding to the formation of the 2-layer hydrate decreases with increasing hydration energy of the interlayer cation. For Ca-, Sr- or Mg-montmoriHonites, simulation of XRD patterns leads to the definition of successive homogeneous states corresponding to the 2-layer hydrate. Furthermore, it yields the water filling ratio corresponding to the different hydration states during adsorption and desorption of water vapor.

Foramina of bones are beginning to yield more information about metabolic rates and activity levels of living and extinct species. This study investigates the relationship between estimated blood flow rate to the femur and body mass among cursorial birds extending back to the Late Cretaceous. Data from fossil foramina are compared with those of extant species, revealing similar scaling relationships for all cursorial birds and supporting crown bird–like terrestrial locomotor activity. Because the perfusion rate in long bones of birds is related to the metabolic cost of microfracture repair due to stresses applied during locomotion, as it is in mammals, this study estimates absolute blood flow rates from sizes of nutrient foramina located on the femur shafts. After differences in body mass and locomotor behaviors are accounted for, femoral bone blood flow rates in extinct species are similar to those of extant cursorial birds. Femoral robustness is generally greater in aquatic flightless birds than in terrestrial flightless and ground-dwelling flighted birds, suggesting that the morphology is shaped by life-history demands. Femoral robustness also increases in larger cursorial bird taxa, probably associated with their weight redistribution following evolutionary loss of the tail, which purportedly constrains femur length, aligns it more horizontally, and necessitates increased robustness in larger species.

A national need is to prepare for and respond to accidental or intentional disasters categorized as chemical, biological, radiological, nuclear, or explosive (CBRNE). These incidents require specific subject-matter expertise, yet have commonalities. We identify 7 core elements comprising CBRNE science that require integration for effective preparedness planning and public health and medical response and recovery. These core elements are (1) basic and clinical sciences, (2) modeling and systems management, (3) planning, (4) response and incident management, (5) recovery and resilience, (6) lessons learned, and (7) continuous improvement. A key feature is the ability of relevant subject matter experts to integrate information into response operations. We propose the CBRNE medical operations science support expert as a professional who (1) understands that CBRNE incidents require an integrated systems approach, (2) understands the key functions and contributions of CBRNE science practitioners, (3) helps direct strategic and tactical CBRNE planning and responses through first-hand experience, and (4) provides advice to senior decision-makers managing response activities. Recognition of both CBRNE science as a distinct competency and the establishment of the CBRNE medical operations science support expert informs the public of the enormous progress made, broadcasts opportunities for new talent, and enhances the sophistication and analytic expertise of senior managers planning for and responding to CBRNE incidents.

Après avoir défini la notion de charge minérale, on étudie la nature et le nombre des défauts cristallins d'argiles kaoliniques. On montre l'influence des défauts d'empilement (interstratification de feuillets potassiques) et des défauts dans le plan (conséquence des substitutions de l'aluminium) sur les propriétés mécaniques des caoutchoucs chargés. Puis on étudie l'influence de la pureté minéralogique et de certains paramètres superficiels sur les performances des produits chargés. Enfin, on propose des méthodes de traitement qui permettent d'accroître les propriétés renforçatrices de la charge. On présente l'évolution comparée de 64 paramètres descriptifs de la charge et du produit fini en définissant des guides de prospection et de traitement qui permettent l'utilisation optimale des réserves charentaises dans le domaine des caoutchoucs naturels.

A study was made of the extent to which the lateral surfaces contribute to the surface area of five kaolinites of different crystallinities. Methods used included the low-temperature adsorption of N2 and Ar as measured by a volumetric technique coupled with microcalorimetry, the interpretation of the adsorption isotherms of alkyldodecylammonium ions, particle-size distribution curves, and shadowed transmission electron microscopy. With the exception of surfactant adsorption and adsorption calorimetry using Ar, these methods gave different and debatable results. For instance, specific lateral surface area values expressed as a percentage of total specific surface area varied from 17·0 to 40·4% for the most crystalline sample and from 12·0 to 54·3% for the least crystalline. It is shown that the decrease in crystallinity of samples is accompanied by a reduction in crystallite size from 0·8 to 0·08 µm and a decrease in lateral surface area from 34·0 to 12·0%.

When applied correctly, atrazine can be used safely in certain areas of the United States for weed control in winter wheat, but persistence in the soil may injure wheat replanted after crop failure. Studies were conducted at Moro, OR, in 1989–90 and 1990–91 to determine the effect of September preplant applications of atrazine at 0.56, 1.12, and 2.24 kg a.i. ha-1 (1X, 2X, and 4X label rates) on wheat seeded at that time and on wheat re-seeded 2 or 6 mo later. Yield of winter wheat re-seeded in November following September atrazine applications was not reduced at any rate. The September-planted wheat was killed with glyphosate in the spring to simulate winter killing, then plots were re-seeded to spring wheat. The commercial rate of atrazine, 0.56 kg ha-1, caused only minor injury to spring wheat, but injury at the 2X and 4X rates was excessive.

Feral rye, commonly referred to as cereal, winter, common, or volunteer rye, is an important weed in winter wheat production in many parts of the United States and the world. Feral rye reduces net profits in the United States by more than $27 million due to lower grain yields, increased dockage, and reduced land values. To date, limited research has been conducted on components that make feral rye a problem in various cropping systems. Herbicide-tolerant wheat technology can be used to manage feral rye, but current efficacy levels are not adequate for high feral rye densities. In addition, the long-term effects that individual management strategies may have on feral rye populations are unknown. This review addresses the physical, environmental, and genetic characteristics of Secale cereale. Current economic impact, management, and research data gaps are also discussed.