Ordering of ruthenium cluster carbonyls in mesoporous silica

The anionic ruthenium cluster carbonylates [Ru6C(CO)16]2- or [H2Ru10(CO)25]2- interspersed with bis(triphenylphosphino)iminium counterions (PPN+) are incorporated from solution into the pores of MCM-41 mesoporous silica (3 nanometers in diameter), where they form tightly packed arrays. These arrays were shown by high-resolution transmission electron microscopy, Fourier transform optical diffraction, and computer simulations to be well ordered both along and perpendicular to the axis of the cylindrical pores. In their denuded state produced by gentle thermolysis, the cluster carbonylates yield nanoparticles of ruthenium that are less well ordered than their assimilated precursors but show good activity as hydrogenation catalysts for hexene and cyclooctene. In both their as-prepared and denuded states, these encapsulated clusters are likely to exhibit interesting electronic and other properties.     

Near extinction of a large, widely distributed fish

Are extinctions of marine vertebrates as rare and unlikely as current data indicate? Long-term research surveys on the continental shelf between the Grand Banks of Newfoundland and southern New England reveal that one of the largest skates in the northwest Atlantic, the barndoor skate (Raja laevis), is close to extinction. Forty-five years ago, research surveys on St. Pierre Bank (off southern Newfoundland) recorded barndoor skates in 10% of their tows; in the last 20 years, none has been caught, and this pattern of decline is similar throughout the range of the species.     

Thermal Modifications of Starch During High‐Temperature Drying of Pasta

Changes in starch at the molecular level during high‐temperature (HT) drying of pasta were studied with differential scanning calorimetry (DSC). Pasta was manufactured from durum wheat semolina into the shape of spaghetti on a pilot‐plant installation. The HT phase (100°C) was applied at relatively high (27 g/100 g, wb), intermediate (20 g/100 g), and low (15 g/100 g) product moisture, respectively. Spaghetti dried at 55°C served as reference samples. The changes in the thermal properties of starch during drying were dependent on the drying conditions. The gelatinization enthalpy of pasta dried at 55°C was reduced by 30% during drying, which indicates a partial melting of the starch crystallites. With the beginning of the HT phase, the gelatinization enthalpy increased to final values that were close to or higher than those of freshly extruded pasta. In general, HT drying of pasta induced a broadening of the gelatinization range. Starch crystallinity remained unchanged during extrusion and drying at HT. Based on a state diagram of starch and on DSC measurements of pasta during drying, it is hypothesized that HT drying favors molecular rearrangements of starch polymers at the double helical level.     

Staling of Bread: Role of Amylose and Amylopectin and Influence of Starch‐Degrading Enzymes

The present investigation aims at understanding the mechanism of bread firming during staling. Changes in the starch fraction due to the addition of amylases and their influence on the texture of bread crumb were studied during aging and after rebaking of stale bread. Pan bread was prepared by a conventional baking procedure. The influence of three different starch‐degrading enzymes, a conventional α‐amylase, a maltogenic α‐amylase, and a β‐amylase were investigated. The mechanical properties of bread were followed by uniaxial compression measurements. The microstructure was investigated by light microscopy, and starch transformations were assessed by differential scanning calorimetry (DSC) and wide‐angle X‐ray powder diffraction. Firming of bread crumb and crystallization of starch are not necessarily in agreement in systems with added amylases. Reorganization of both starch fractions, amylopectin and amylose, and the increase of starch network rigidity due to increase of polymer order are important during aging. Starch‐degrading enzymes act by decreasing the structural strength of the starch phase; for instance, by preventing the recrystallization of amylopectin or by reducing the connectivity between crystalline starch phases. On the other hand, starch‐degrading enzymes may also promote the formation of a partly crystalline amylose network and, by this, contribute to a kinetic stabilization of the starch network. Based on the results, a model for bread staling is proposed, taking into account the biphasic nature of starch and the changes in both the amylose and amylopectin fraction.     

Scrub-itch mite infestation in the endangered bridled nailtail wallaby

Skin lesions on the ears and inguinal and axillary regions of a number of adult animals within a captive population of the endangered bridled nailtail wallaby ( Onychogalea fraenata ) were associated with the trombiculid mite, Eutrombicula hirsti . The local inflammatory response of these Australian marsupials is described.     

Risk Sensitivity and Hunter Perceptions of Chronic Wasting Disease Risk and Other Hunting,Wildlife, and Health Risks

This article examined relationships among hunter perceptions of personal health risks from chronic wasting disease (CWD), knowledge and information about CWD, and perceptions of other hunting, wildlife, and health risks. Data were obtained from surveys of 2,725 deer and elk hunters in Colorado. Cluster analysis grouped hunters into no (42%), slight (44%), and moderate (14%) risk groups based on perceptions of personal health risks from CWD (e.g., concern about health, become ill from CWD). There were minimal differences among groups in demographics, information sources, and knowledge about CWD. Hunters who perceived higher health risks from CWD (i.e., moderate risk), however, perceived greater risks associated with CWD to other humans, CWD to wildlife, hunting to personal health, other diseases to health, and the future of hunting. These findings illustrated the concept of risk sensitivity where hunters who perceived higher risks from CWD were predisposed to rate all other risks as large.     

Organogenesis and foetal haemodynamics during the normal gestation of healthy black‐rumped agoutis (Dasyprocta prymnolopha,Wagler, 1831) bred in captivity

The objective of this study was to define the patterns of organogenesis and foetal haemodynamics during the normal gestation of healthy agoutis (Dasyprocta prymnolopha) kept in captivity. Thirty pregnant agoutis that ranged in size from small to medium and weighed between 2.5 and 3 kg underwent B‐mode and Doppler ultrasonography for the biometric evaluation of the foetal organs. The foetal aortic blood flow proved to be predominantly systolic, and the measured flow velocity was 78.89 ± 2.95 cm/s, with a maximum pressure gradient of 2.12 ± 0.27 mmHg. The liver was characterized by its large volume, occupying the entire cranial aspect of the abdominal cavity, and it was associated cranially with the diaphragm and caudally with the stomach. The flow velocity in the portal vein was estimated to equal 12.17 ± 2.37 cm/s, with a resistivity index of 0.82 ± 0.05. The gallbladder was centrally located and protruded cranially towards the diaphragm. The spleen was visualized as an elongated structure with tapered cranial and caudal extremities, and the foetal kidneys were visualized bilaterally in the retroperitoneal region, with the right kidney positioned slightly more cranially than the left. The morphological characterization and hemodynamic analysis of the foetal organs of black‐rumped agoutis via B‐mode and Doppler ultrasonography allow determination of the vascular network and of reference values for the blood flow required for perfusing the anatomical elements essential for maintaining the viability of foetuses at different gestational ages.     

A specialist-generalist classification of the arable flora and its response to changes in agricultural practices

Background  

Theory in ecology points out the potential link between the degree of specialisation of organisms and their responses to disturbances and suggests that this could be a key element for understanding the assembly of communities. We evaluated this question for the arable weed flora as this group has scarcely been the focus of ecological studies so far and because weeds are restricted to habitats characterised by very high degrees of disturbance. As such, weeds offer a case study to ask how specialization relates to abundance and distribution of species in relation to the varying disturbance regimes occurring in arable crops.