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David Jacques

Publications and source records attributed to David Jacques.

3 recordsLinked to original sources

Multiwall carbon nanotubes: synthesis and application.

Chemical vapor deposition (CVD) is the most promising synthesis route for economically producing large quantities of carbon nanotubes. We have developed a low-cost CVD process for the continuous production of aligned multiwall carbon nanotubes (MWNTs). Here we report the effects of reactor temperature, reaction time, and carbon partial pressure on the yield, purity, and size of the MWNTs produced. A simple method for purifying and healing structural defects in the nanotubes is described. The dispersion of nanotubes in polymer matrices has been investigated as a means of deriving new and advanced engineering materials. These composite materials have been formed into fibers and thin films and their mechanical and electrical properties determined.

Journal Article↗

A retrospective study of 40 dogs with polyarthritis.

OBJECTIVE: To characterize the epidemiologic, clinical, laboratory, and radiographic findings from dogs with polyarthritis (PA). STUDY DESIGN: Retrospective clinical study. SAMPLE POPULATION: Forty dogs. METHODS: Medical records of 40 dogs with a diagnosis of PA were reviewed. Retrieved data included breed, age at admission, sex, weight, clinical signs, and the results of synovial fluid analysis, complete blood count, serum chemistry profile, urinalysis, serologic screening tests for infectious diseases, and radiographic examination of affected joints. RESULTS: The incidence of PA was 0.37%. Twenty-nine breeds were represented; 16 dogs were male, and 24 were female. Mean body weight was 20.1 +/- 15 kg. The mean age at admission was 5.6 +/- 4 years. Eighty percent of dogs with PA had difficulty or reluctance walking, 35% were lame, 33% had spontaneous vocalization without any obvious reason, 20% had exercise intolerance, 18% were febrile, and 7.5% had an inability to rise or move. Joint pain was identified in 40% of dogs. Synovial fluid color varied from colorless (36%) to yellow-tinged (36%) or hemorrhagic (28%). Synovial fluid mean cell count varied from 10 cells (400x) to 50 cells (1,000x). Leukocytosis occurred in 59% of the dogs and was more frequently identified in dogs with very severe synovial inflammation. Thirty-one percent of affected dogs were anemic. Serum biochemical profiles were considered abnormal in 13% of the dogs. Joint radiography did not identify erosive arthritis. CONCLUSIONS: PA is a common cause of locomotor abnormalities in dogs; however, true lameness and articular pain are not common clinical findings in dogs with PA. CLINICAL RELEVANCE: PA should be considered in the differential diagnosis for all dogs with difficulty walking.

Animals↗

Low-temperature synthesis of large-area CNx nanotube arrays.

Well-aligned nitrogen-doped multiwall carbon nanotube arrays have been successfully grown over large areas on quartz and silicon wafers by floating-catalyst chemical vapor deposition at low temperatures (600 degrees C). These nitrogen-including nanotubes, derived from pyridine-ferrocene mixtures, have smaller outer diameters but larger inner diameters compared with carbon nanotubes grown from a xylene-ferrocene mixture under similar conditions. The N-doped nanotubes exhibit bamboo-like structures in the core. Elemental analysis and electron energy loss spectroscopy analysis show that the as-prepared nanotubes contain as much as 2.62 wt.% N, with most of the N concentrated in the inner few shells of the nanotube. Such large-scale arrays of well-aligned N-doped nanotubes on silicon wafers have a current density as high as 23.8 mA/cm2 at an applied electric field of 17 V/micron, which can be further improved by patterning the tubes and coating the silicon substrate with a conductive thin metal film for the fabrication of flat panel displays.

Crystallization↗