Extended Nucleation and Superfocusing in Colloidal Semiconductor Nanocrystal Synthesis.

Hot-injection synthesis is renowned for producing semiconductor nanocolloids with superb size dispersions. Burst nucleation and diffusion-controlled size focusing during growth have been invoked to rationalize this characteristic yet experimental evidence supporting the pertinence of these concepts is scant. By monitoring a CdSe synthesis - with X-ray scattering, we find that nucleation is an extended event that coincides with growth during 15-20% of the reaction time.

Note: Laser-cut molybdenum grids for a retarding field energy analyzer.

A retarding field energy analyzer (RFEA) with grids created by laser-cutting a honeycomb mesh in a 50 μm thick molybdenum foil is presented. The flat grids span an area of 1 cm and have high transmission (20 μm wide walls between 150 μm wide meshes). The molybdenum grids were tested in a 3-grid RFEA configuration with an analyzer depth of 0.

Validation of a calf-side β-hydroxybutyrate test and its utility for estimation of starter intake in dairy calves around weaning.

Recent research suggests that circulating β-hydroxybutyrate (BHB) levels may be a meaningful indicator of grain intake and rumen development in pre-ruminant calves. As such, BHB levels may be a surrogate measure of rumen function to contribute to minimal weaning stress during the transition from liquid to solid feed. The primary objective of this study was to determine the optimal cut-point of circulating BHB levels that would be predictive of sufficient grain intake and rumen development for a successful transition from liquid to solid feed at the time of weaning.

Evaluation of a Brix refractometer to estimate serum immunoglobulin G concentration in neonatal dairy calves.

The objective of this study was to evaluate the utility of a digital Brix refractometer for the assessment of success of passive transfer of maternal immunoglobulin compared with the measurement of serum total protein (STP) by refractometry. Blood samples (n = 400) were collected from calves at 3 to 6d of age. Serum IgG concentration was determined by radial immunodiffusion (RID), and STP and percentage Brix (%Brix) were determined using a digital refractometer.

Comparison of three commercially available amplification assays, AMP CT, LCx, and COBAS AMPLICOR, for detection of Chlamydia trachomatis in first-void urine.

We compared the Gen-Probe transcription-mediated amplification assay (AMP CT), the Abbott LCx assay, and the Roche COBAS AMPLICOR assay for the detection of Chlamydia trachomatis in a mixed population in urine samples. First-void urine, urethral specimens, and cervical specimens in females were obtained from 1,000 patients (544 males and 456 females) visiting the outpatient sexually transmitted disease clinic of our hospital. The prevalence of C.