Diffusing-Wave Spectroscopy of Dynamics in a Three-Dimensional Granular Flow

Diffusing-wave spectroscopy was used to measure the microscopic dynamics of grains in the interior of a three-dimensional flow of sand. The correlation functions show that minutely separated grains fly from collision to collision with large random velocities. On a time scale 10(3) to 10(4) times longer than the average time between collisions, the grains displayed slow, collective rearrangements, which, at the long-time limit, produced diffusive dynamics.     

Rapid changes in tree leaf chemistry induced by damage: evidence for communication between plants

Potted poplar ramets showed increased concentrations and rates of synthesis of phenolic compounds within 52 hours of having 7 percent of their leaf area removed by tearing, as did undamaged plants sharing the same enclosure. Damaged sugar maple seedlings responded in a manner similar to that of the damaged poplars. Nearby undamaged maples had increased levels of phenolics and hydrolyzable and condensed tannin within 36 hours, but exhibited no change in rates of synthesis. An airborne cue originating in damaged tissues may stimulate biochemical changes in neighboring plants that could influence the feeding and growth of phytophagous insects.     

Supramolecular self-assembly of lipid derivatives on carbon nanotubes

Images of the assembly of surfactants and synthetic lipids on the surface of carbon nanotubes were obtained by transmission electron microscopy. Above the critical micellar concentration, sodium dodecyl sulfate (SDS) forms supramolecular structures made of rolled-up half-cylinders on the nanotube surface. Depending on the symmetry and the diameter of the carbon nanotube, we observed rings, helices, or double helices. Similar self-assemblies were also obtained with several synthetic single-chain lipids designed for the immobilization of histidine-tagged proteins. At the nanotube-water interface, permanent assemblies were produced from mixed micelles of SDS and different water-insoluble double-chain lipids after dialysis of the surfactant. Such arrangements could be further exploited for the development of new biosensors and bioelectronic nanomaterials.     

Deeply inverted electron-hole recombination in a luminescent antibody-stilbene complex

The blue-emissive antibody EP2-19G2 that has been elicited against trans-stilbene has unprecedented ability to produce bright luminescence and has been used as a biosensor in various applications. We show that the prolonged luminescence is not stilbene fluorescence. Instead, the emissive species is a charge-transfer excited complex of an anionic stilbene and a cationic, parallel pi-stacked tryptophan. Upon charge recombination, this complex generates exceptionally bright blue light. Complex formation is enabled by a deeply penetrating ligand-binding pocket, which in turn results from a noncanonical interface between the two variable domains of the antibody.     

Effect of sugars on transport of alanine in intestine

The eflect of glucose and galactose on transport of alanine by rabbit ileum has been investigated. Transmural transport and cellular ac cumulation of the amino acid were in hibited by the sugars, but alanine in flux across the mucosal border of the cells was unaltered.     

Introduction of nucleophiles and spectroscopic probes into antibody combining sites

A general chemical strategy has been developed whereby antibody combining sites can be selectively derivatized with natural or synthetic molecules, such as catalytic groups, drugs, metals, or reporter molecules. Cleavable affinity labels were used to selectively introduce a thiol into the combining site of the immunoglobulin A MOPC 315. This thiol acted both as a nucleophile to accelerate ester thiolysis 60,000-fold and as a handle for selectively derivatizing the antibody with additional functional groups. For example, derivatization of the antibody with a fluorophore made possible a direct spectroscopic assay of antibody-ligand complexation. This chemistry should not only extend our ability to exploit antibody specificity in chemical catalysis, diagnostics, and therapeutics, but may also prove generally applicable to the functional modification of other proteins for which detailed structural information is unavailable.     

Effect of vaccination with recombinant canine distemper virus vaccine immediately before exposure under shelter-like conditions

Vaccination with modified-live virus (MLV) canine distemper virus (CDV) vaccine has historically been recommended for animals in high-risk environments because of the rapid onset of immunity following vaccination. Recombinant CDV (rCDV) vaccine was deemed a suitable alternative to MLV-CDV vaccination in pet dogs, but insufficient data precluded its use where CDV was a serious threat to puppies, such as in shelters, kennels, and pet stores. In this study, dogs experimentally challenged hours after a single dose of rCDV or MLV vaccine became sick but recovered, whereas unvaccinated dogs became sick and died. Dogs vaccinated with a single dose of rCDV or MLV vaccine 1 week before being experimentally challenged remained healthy and showed no clinical signs. Dogs given one dose of rCDV vaccine hours before being placed in a CDV-contaminated environment did not become sick. These findings support the hypothesis that rCDV vaccine has a similar time-to-immunity as MLV-CDV vaccines and can likewise protect dogs in high-risk environments after one dose.     

Sodic Soil Reclamation Potential of Gypsum and Biocharadditions: Influence on Physicochemical Properties and Soil Respiration

Reclamation of sodic soils is proving increasingly vital as greater land area becomes salt-affected in the northern Great Plains of the United States. Flue gas desulfurization gypsum (FGDG) can be an agriculturally important resource for increasing land productivity through the amelioration of sodic soils. Biochar is also considered as an aid in reclaiming degraded soils. In this incubation study, two rates of FGDG (33.6 Mg ha^?1 and 66.2 Mg ha^?1), two rates of biochar made from sugar beet (Beta vulgaris L.) pulp (16.8 Mg ha^?1), and one rate of FGDG combined with one rate of biochar (33.6 Mg ha^?1 ea.) were applied to a sodic soil. Soil physicochemical properties, including cationic exchange, pH, electrical conductivity (EC_e), sodium adsorption ratio (SAR_e), total organic carbon (TOC), water retention, and soil respiration rate, were assessed during and at the end of the incubation period. Addition of FGDG to sodic soil increased EC_e from 3.5 to 8.4 dS m^?1 and decreased SAR_e from 16 to 9. Biochar addition to sodic soil increased TOC from 62.2 to 99.5 μg g^?1 and increased soil respiration rate (mg C kg^?1 soil day^?1) on every measurement period. When FGDG and biochar were both added to the sodic soil, TOC did not significantly improve; however, EC_e increased from 3.5 to 7.7 dS m^?1, SAR_e decreased from 16 to 9, and soil respiration rate increased for all measurements. The results confirm there is potential for FGDG and biochar to reclaim sodic soils alone, and applied in combination.