Capillary electrophoresis of ultrasmall carboxylate functionalized silicon nanoparticles

Capillary electrophoresis is used to separate ultrasmall ( approximately 1 nm) carboxylate functionalized Si nanoparticles (Si-np-COO(-)) prepared via hydrosilylation with an omega-ester 1-alkene. The electropherograms show a monodisperse Si core size with one or two carboxylate groups added to the surface. On-column detection of their laser-induced fluorescence demonstrates that the individual Si-np-COO(-) have narrow emissions (full width at half maximum = 30-40 nm) with a nearly symmetric lineshape. Preparative scale electrophoresis should be a viable route for purification of the Si-np-COO(-) for further study and future applications.     

Assaying neurotransmitters in and around single neurons with information-rich detectors

Techniques to study the chemical environment in and around individual neurons are reviewed, with an emphasis on methods to assay single cells for neurotransmitters and neuromodulators that do not require analyte preselection. Current capabilities of capillary-based microseparations and mass spectrometry are highlighted for this application. Methods to combine multiple analytical techniques to provide chemical, spatial and temporal information are described.     

MALDI Mass Spectrometry Imaging of Neuronal Cell Cultures

Mass spectrometry imaging (MSI) provides the ability to detect and identify a broad range of analytes and their spatial distributions from a variety of sample types, including tissue sections. Here we describe an approach for probing neuropeptides from sparse cell cultures using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MSI—at single cell spatial resolution—in both MS and tandem MS modes. Cultures of Aplysia californica neurons are grown on an array of glass beads embedded in a stretchable layer of Parafilm M. As the membrane is stretched, the beads/neurons are separated physically and the separated beads/neurons analyzed via MALDI TOF MS. Compared with direct MS imaging of samples, the stretching procedure enhances analyte extraction and incorporation into the MALDI matrix, with negligible analyte spread between separated beads. MALDI tandem MSI using the stretched imaging approach yields localization maps of both parent and fragment ions from Aplysia pedal peptide, thereby confirming peptide identification. This methodology represents a flexible platform for MSI investigation of a variety of cell cultures, including functioning neuronal networks.     

地方高校化工专业学生创新创业能力提升模式探索

针对当前地方高校化工类专业创新创业人才供需现状,结合地方高校实际,提出了化工专业学生虚拟公司设计实训、校内仿真实训、校内外实践基地一体化创新创业能力提升实践教学模式,具有"内外结合、虚实结合、阶梯式推进"等特色。经探索,采用该模式可走出一条具有地方高校特色的实践教学新路径,可形成工科专业实践教学的示范模式,对于提升地方高校的竞争力具有积极意义。     

铁的析氢腐蚀实验探究

针对析氢腐蚀实验中出现的异常现象,依据金属电化学腐蚀原理,通过实验探究确定影响析氢腐蚀实验的主要因素——氧气。在此基础之上,设计出演示吸氧腐蚀、析氢腐蚀的套管实验以及析氢腐蚀的微型化实验方案。     

The growth of valuations on rational function fields in two variables

Given a valuation on the function field , we examine the set of images of nonzero elements of the underlying polynomial ring under this valuation. For an arbitrary field , a Noetherian power series is a map that has Noetherian (i.e., reverse well-ordered) support. Each Noetherian power series induces a natural valuation on . Although the value groups corresponding to such valuations are well-understood, the restrictions of the valuations to underlying polynomial rings have yet to be characterized. Let denote the images under the valuation of all nonzero polynomials of at most degree in the variable . We construct a bound for the growth of with respect to for arbitrary valuations, and then specialize to valuations that arise from Noetherian power series. We provide a sufficient condition for this bound to be tight.

     

On generators and cogenerators

We consider the existence of generators and cogenerators in several categories. In many cases the non-existence of cogenerators results from the construction of arbitrarily high dimensional simple (restricted) Lie algebras. The existence of generators in the Hopf algebra categories results from the existence of generators in a certain coalgebra category and the construction of a free Hopf algebra on a coalgebra.