Background: One of the factors limiting successful processing of alpaca (Vicugna pacos) semen is the viscosity of seminal plasma. The viscous nature of the collected ejaculate has hindered sperm cryopreservation as well as artificial insemination (AI) under field conditions. Aims: The objective of this investigation was to evaluate recovery, motility, ...

Gradient surfaces are emerging tools for investigating mammalian cell-surface interactions in high throughput. We demonstrate the electrochemical fabrication of an orthogonal gradient platform combining a porous silicon (pSi) pore size gradient with an orthogonal gradient of peptide ligand density. pSi gradients were fabricated via the anodic etching of a silicon wafer with pore sizes ranging f...

Rat cerebral cortex was homogenized in a sucrose-free medium and a number of intracellular melnbrane fractions were isolated therefrom by means of differential and density-gradient centrifugation. The mitochondrial and microsomal membrane fractions, as well as the separated rough and smooth endoplasmic reticulum components of the latter, were subjected to zonal density gradient electrophoresis....

There are numerous techniques for sampling density gradients in experiments involving the preparative ultracentrifuge. Among the sampling procedures used are: drawing liquid samples from the top of the density gradient with modified pipettes (J. B. Sinclair et al., Phytopathology 47:372, 1957), displacement through the top of the density gradient (E. Huff, H. Oxley, and C. S. Silverman, J. Bact...

Single-spin density-gradient ultracentrifugation (DUC) has proven to be a reproducible method for detection of low-density-lipoprotein (LDL) heterogeneity. Recently another method has been described for this: gradient gel electrophoresis (GGE) of serum, a method that might be more suitable for screening. To gain insight into the relationship of GGE to DUC and into their reproducibility, we dete...

We have analyzed the performance of several widely used density functional theory procedures, namely B-P86, B-PW91, B-LYP, B3-P86, B3-PW91, and B3-LYP, for the E3 set of thermochemical properties. Each of these procedures employs a local density approximation (LDA) functional and a gradient correction for the correlation energy. We find that the VWN3 LDA functional in B-P86, B-PW91, B3-P86, and...

Diffusion magnetic resonance imaging (MRI) methods for axon diameter mapping benefit from higher maximum gradient strengths than are currently available on commercial human scanners. Using a dedicated high-gradient 3T human MRI scanner with a maximum gradient strength of 300 mT/m, we systematically studied the effect of gradient strength on in vivo axon diameter and density estimates in the hum...

This protocol describes the isolation of native protein complexes by density gradient ultracentrifugation. The outcome of an affinity capture and native elution experiment is generally a mixture of (1) the complex(es) associated with the protein of interest under the specific conditions of capture, (2) fragments of the complex generated by degradation or disassembly during the purification proc...