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1.  Alternating layer addition approach to CdSe/CdS core/shell quantum dots with near-unity quantum yield and high on-time fractions 
We report single-particle photoluminescence (PL) intermittency (blinking) with high on-time fractions in colloidal CdSe quantum dots (QD) with conformal CdS shells of 1.4 nm thickness, equivalent to approximately 4 CdS monolayers. All QDs observed displayed on-time fractions > 60% with the majority > 80%. The high-on-time-fraction blinking is accompanied by fluorescence quantum yields (QY) close to unity (up to 98% in an absolute QY measurement) when dispersed in organic solvents and a monoexponential ensemble photoluminescence (PL) decay lifetime. The CdS shell is formed in high synthetic yield using a modified selective ion layer adsorption and reaction (SILAR) technique that employs a silylated sulfur precursor. The CdS shell provides sufficient chemical and electronic passivation of the QD excited state to permit water solubilization with greater than 60% QY via ligand exchange with an imidazole-bearing hydrophilic polymer.
PMCID: PMC4052982  PMID: 24932403
2.  The Association of Menopausal Status with Physical Function: The Study of Women’s Health Across the Nation (SWAN) 
Menopause (New York, N.Y.)  2012;19(11):1186-1192.
To determine if post-menopausal status is associated with self-reported limitations in physical function.
SWAN is a multi-site, multi-ethnic, longitudinal study of midlife women. Women aged 45–57 years (N=2,566) completed the Medical Outcomes Study Short-Form Physical Function Scale at visit 4 (2000–2001); scores created a 3-category variable of physical function limitations: none (86–100), moderate (51–85) and substantial (0–50). Menopausal status in SWAN is a 5-category list variable based on menstrual bleeding patterns and gynecological surgery. Pre-and peri-menopausal women using hormones (n=284) or missing physical function scores (n=46) were excluded. Multinomial logistic regression was used to relate physical function and menopausal status adjusting for age, ethnicity, site, education, body mass index (BMI), self-reported diabetes, hypertension, arthritis, depressive symptoms, smoking and hormone use among postmenopausal women.
Of 2,236 women, 8% were pre-, 51% early peri-, 12% late peri-, 24% natural post-, and 5% surgical post-menopausal status. In the full model, substantial limitations in physical function were higher in post-menopausal compared to pre-menopausal women whether it occurred naturally (OR 3.82; 95% CI: 1.46–10.0) or surgically (OR 3.54; 95% CI: 1.15–10.84). These associations were attenuated by higher BMI and depressive symptoms, but remained significant. Moderate limitations in physical function were not significantly related to menopausal status.
Women with surgical or naturally occurring post-menopause reported greater limitations in physical function than pre-menopausal women, independent of age, only partly explained by higher BMI and depressive symptoms. This suggests that physiologic changes of menopause could contribute directly to limitations in physical function.
PMCID: PMC3526111  PMID: 22760087
Physical functioning; Functional limitations; Menopause; Menopausal status; SF-36
3.  A qualitative study of predelivery counselling for extreme prematurity 
Paediatrics & Child Health  2012;17(8):432-436.
To ascertain from parents of neonates born before 27 weeks’ gestational age how to improve predelivery counselling for delivery room resuscitation.
Qualitative ethnographic study using semistructured, face-to-face interviews of 10 families. Data were analyzed using a constant comparative method.
Parents had no previous knowledge about prematurity. They would have preferred prioritized information during predelivery counselling focused on the immediate risks to their child. Resuscitation wishes were inconsistently sought. Opportunities for repeat discussions involving both parents were often missed. Parents agreed that the opportunity to explicitly state resuscitation wishes should be offered. Additional materials, such as pamphlets or videos, would improve counselling.
Information about prematurity should be offered when the pregnancy is deemed high risk, with repeat counselling opportunities for both parents to discuss options. Once the decision is made to resuscitate, parents want the neonatal team to convey a message of hope and compassion.
PMCID: PMC3474383  PMID: 24082803
Counselling; Informed consent; Prematurity; Resuscitation; Qualitative
4.  Environmental Factors Influencing Gene Transfer Agent (GTA) Mediated Transduction in the Subtropical Ocean 
PLoS ONE  2012;7(8):e43506.
Microbial genomic sequence analyses have indicated widespread horizontal gene transfer (HGT). However, an adequate mechanism accounting for the ubiquity of HGT has been lacking. Recently, high frequencies of interspecific gene transfer have been documented, catalyzed by Gene Transfer Agents (GTAs) of marine α-Proteobacteria. It has been proposed that the presence of bacterial genes in highly purified viral metagenomes may be due to GTAs. However, factors influencing GTA-mediated gene transfer in the environment have not yet been determined. Several genomically sequenced strains containing complete GTA sequences similar to Rhodobacter capsulatus (RcGTA, type strain) were screened to ascertain if they produced putative GTAs, and at what abundance. Five of nine marine strains screened to date spontaneously produced virus-like particles (VLP's) in stationary phase. Three of these strains have demonstrated gene transfer activity, two of which were documented by this lab. These two strains Roseovarius nubinhibens ISM and Nitratireductor 44B9s, were utilized to produce GTAs designated RnGTA and NrGTA and gene transfer activity was verified in culture. Cell-free preparations of purified RnGTA and NrGTA particles from marked donor strains were incubated with natural microbial assemblages to determine the level of GTA-mediated gene transfer. In conjunction, several ambient environmental parameters were measured including lysogeny indicated by prophage induction. GTA production in culture systems indicated that approximately half of the strains produced GTA-like particles and maximal GTA counts ranged from 10–30% of host abundance. Modeling of GTA-mediated gene transfer frequencies in natural samples, along with other measured environmental variables, indicated a strong relationship between GTA mediated gene transfer and the combined factors of salinity, multiplicity of infection (MOI) and ambient bacterial abundance. These results indicate that GTA-mediated HGT in the marine environment with the strains examined is favored during times of elevated bacterial and GTA abundance as well as in areas of higher salinity.
PMCID: PMC3419701  PMID: 22905268

Results 1-4 (4)