ABSTRACT
Metal oxide-based nanoparticles of cobalt or nickel were deposited inside the pores and on the surface of hexagonal mesoporous silicas by a direct synthesis technique using Pluronic P85 and P123 surfactants as structure directing agents with the appropriate metal phthalocyanine as a metal precursor. Metal loadings were between 0.4-3.2 wt.%. XPS studies showed that the initial form of the metal oxide nanoparticles were [CoO] and [NiO] respectively. Samples of these materials formed from the P85 surfactant and 3.0 wt.% were used to grow carbon nanotubes (CNTs) from acetylene feedstock in a catalytic chemical vapour deposition (CCVD) reactor at 800 degrees C. CNT growth appeared to be random and the CNTs had diameters ranging from < 10 to > 90 nm. Treatment of the metal impregnated silicas with nitric acid produced materials which, under the same CNT growth conditions, afforded more uniform CNTs with diameters between 5-15 nm. No significant loss in mesophase ordering was seen in the TEM, PXRD or nitrogen physisorption analysis of the acid washed samples. CNTs grown with cobalt impregnated silicas formed with the P123 surfactant had diameters in the range 15-25 nm. Raman spectroscopy of the CNT products showed the nanotubes were highly graphitised and of good quality.
ABSTRACT
Semiconductor nanowires of silicon have been synthesized within the pores of mesoporous silica using a novel supercritical fluid solution-phase approach. Mesoporous silica, formed by the hydrolysis of tetramethoxysilane (TMOS) in the presence of a triblock copolymer surfactant, was employed for the nucleation and growth of quantum-confined nanowires. The filling of the silica mesopores with crystalline silicon and the anchoring of these nanowires to the sides of the pores were confirmed by several techniques including electron microscopy, powder X-ray diffraction, 29Si magic angle spinning nuclear magnetic resonance, infrared spectroscopy, and X-ray fluorescence. Effectively, the silica matrix provides a means of producing a high density of stable, well-ordered arrays of semiconductor nanowires in a low dielectric medium. The ordered arrays of silicon nanowires also exhibited discrete electronic and photoluminescence transitions that could be exploited in a number of applications, including nanodevices and interconnects.
ABSTRACT
OBJECTIVE: To evaluate prospectively the 1989 Centers for Disease Control recommendations for treatment of gonorrhea in pregnancy. METHODS: Two hundred fifty-two women referred with probable endocervical gonorrhea had pre-treatment endocervical, rectal, and oral cultures for Neisseria gonorrhoeae and direct fluorescent antibody testing for Chlamydia trachomatis. They were assigned randomly to receive ceftriaxone 250 mg intramuscularly (IM), spectinomycin 2 g IM, or amoxicillin 3 g orally plus probenecid 1 g orally. Treatment was unblinded and in a 1:1:1 distribution. RESULTS: Two hundred forty-five women (97%) had endocervical infection, 68 (27%) had rectal infection, and 17 (7%) had pharyngeal infection. One hundred two of 252 women (40%) had concomitant endocervical C trachomatis. The overall efficacy was 235 of 252 subjects (93%) (95% confidence interval [CI] 90.1-96.4%). Ceftriaxone was effective in 80 of 84 cases (95%) (95% CI 90.6-99.9%), amoxicillin with probenecid was effective in 75 of 84 cases (89%) (95% CI 82.5-96%), and spectinomycin was effective in 80 of 84 cases (95%) (95% CI 90.6-99.9%). No significant difference was noted in overall efficacy or by site of infection. There was no increased incidence of congenital malformations in the offspring spring of any treatment group. CONCLUSIONS: Ceftriaxone and spectinomycin are safe and effective for the treatment of gonorrhea in pregnancy. Amoxicillin with probenecid has lower efficacy and is not recommended for treatment of gonococcal infection in pregnancy.
