A hybrid electrochemical/chemical (E/C) synthesis of zinc oxide
(ZnO) nanoparticles and
films is described. The E/C procedure involves two steps: Zinc
metal was first electrochemically deposited at basal-plane oriented graphite electrode surfaces from
dilute aqueous
solutions; then this deposit was permitted to spontaneously oxidize and
dehydrate at open
circuit in the pH = 1.0 plating solution. Deposition was
size-selective, and wurtzite phase
ZnO nanocrystallites having mean diameters in the range from 15 to 100
Å were obtained
using this approach. Relative standard deviations of the particle
diameter for ZnO particle
dispersions varied from 25 to 50%. Polycrystalline ZnO films of
100−400 Å in thickness
were also obtained by depositing larger quantities of zinc metal in the
first step of the
synthesis. For ZnO particles (dia. < 80 Å), electron diffraction
analysis revealed a preferred
orientation for ZnO crystallites where the c-axis of the
wurtzite unit cell was oriented
perpendicular to the plane of the graphite surface, but X-ray powder
diffraction data indicated
that this orientational preference was lost when larger quantities of
zinc were deposited
and ZnO films were obtained. Luminescence spectra for the ZnO
films prepared using this
E/C method consisted of a single exciton band near 3.2 eV at room
temperature with no
deep trap state emission. At low temperatures (20 K), this exciton
band split into a cleanly
resolved and fully assignable phonon loss progression.
Silver nanoparticles having a mean height ranging from 2 to 20 nm have been electrodeposited on
hydrogen-terminated n2+-Si(100) surfaces. The deposition of silver was carried out potentiostatically from
dilute ([Ag+] = 1 mM) acetonitrile-based solutions using a large overpotential, E
appl = −800 mV versus
Ag+/Ag0, and a voltage pulse duration ranging from 2 to 25 ms. Under these conditions, less than 0.20 of
a silver monolayer was deposited, and this silver was present on the surface as silver nanoparticles which
were similar in size. The metallic nature of these nanoparticles was confirmed using selected area electron
diffraction. The evolution of the areal density of nanoparticles, and the nanoparticle height were both
tracked as a function of the plating pulse duration ex situ using noncontact atomic force microscopy. As
the pulse duration was increased from 2 to 25 ms, the mean nanoparticle height increased from 2 to 20
nm while the areal density of nanoparticles concurrently increased from 1 to 3 × 108 cm-2 to 2−2.5 × 109
cm-2. This result shows conclusively that the nucleation of silver on Si(100) is progressive in this time
domain.
Many hospitals wish to improve their patients’ experience of care. In order to learn whether social media could be used as a tool to engage patients and to identify opportunities for hospital quality improvement (QI), we solicited patients’ narrative feedback on the Baystate Medical Center (BMC) Facebook page during a three-week period in 2014. Two investigators used directed qualitative content analysis to code comments and descriptive statistics to assess the frequency of selected codes and themes. We identified common themes, including: 1.) comments about staff (17/37 respondents, 45.9%); 2.) comments about specific departments (22/37, 59.5%); 3.) comments on technical aspects of care, including perceived errors and inattention to pain control (9/37, 24.3%); and 4.) comments describing the hospital physical plant, parking, and amenities (9/37, 24.3%). A small number (n=3) of patients repeatedly responded, accounting for 30% (45/148) of narratives. While patient feedback on social media could help to drive hospital QI efforts, any potential benefits must be weighed against the reputational risks, the lack of representativeness among respondents, and the volume of responses needed to identify areas of improvement.
The current status of the Louisiana State University Center for Advanced Microstructures and Devices electron storage ring, beamlines, and the scientific program are described.
A superconducting 7 T wiggler is under fabrication in a collaboration between Budker INP and LSU CAMD. The wiggler magnet has been successfully tested inside a bath cryostat and a maximum ®eld of 7.2 T was achieved after six quenches. The main parameters of the wiggler and the method of the wiggler installation onto the storage ring are discussed.
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