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Biomedical subjects

E Schneiderman

Publications and source records attributed to E Schneiderman.

9 recordsLinked to original sources
PubMed2001

Use of dyes to investigate migration of the chiral selector in CFFE and the impact on the chiral separations.

Continuous free flow electrophoresis was investigated as a tool for the preparative chiral separation of piperoxan enantiomers using sulfated beta-cyclodextrin (sbeta-CD) as the chiral additive. Bulk migration of sbeta-CD was confirmed using LC-MS analysis of the individual fractions collected and visualized with the addition of crystal violet to the separation buffer. In the absence of sbeta-CD, the crystal violet-containing buffer was reddish/purple and the crystal violet was deflected cathodically in the chamber. In the presence of sbeta-CD, the crystal violet-containing buffer was blue and was deflected anodically. However, formation of accumulation and depletion zones was apparent in both cases. The addition of sbeta-CD to the cathodic wash solution allowed for almost complete resolution of the piperoxan enantiomers with a processing rate of 0.45 mg/ h.

Coloring Agents↗
PubMed2000

Cyclodextrins: a versatile tool in separation science.

Cyclodextrins have been used extensively in separation science because they have been shown to discriminate between positional isomers, functional groups, homologues and enantiomers. This property makes them one of the most useful agents for a wide variety of separations. The main goal of this review is a discussion of somewhat more exotic applications of cyclodextrins to separation methods. Techniques examined in detail include gel electrophoresis, isotachophoresis, isoelectric focusing, preparative scale electrophoretic techniques, thin-layer chromatography, electrochemically modulated liquid chromatography, use of monolithic media in liquid chromatography, microdialysis, separation on hollow fibers, foam flotation enrichment, solid- and liquid-phase extractions, countercurrent chromatography, separation through liquid and composite membranes, and cyclodextrin applications in molecularly imprinted polymers. Since a lot of attention has been paid to use of cyclodextrins in capillary electrophoresis, liquid, gas and supercritical fluid chromatography, these techniques will be only briefly discussed. The second goal of this review is a discussion of a scaling-up the analytical separations to semi-preparative or preparative techniques. It was found that despite a need for large scale separations in the industry, development of these techniques has been somewhat lagging behind development of miniaturized analytical separations. It is hoped that the focus on areas outside more traditional separation applications might stimulate further research.

Chromatography↗
PubMed1996

Condylar movement and centric relation in patients with internal derangement of the temporomandibular joint.

This study was designed to compare the reproducibility of the condylar translation pathway and the centric relation position in patients with and without internal derangement of the temporomandibular joint. Reproducibility of condylar movement and variability of the axis point of condylar rotation in centric relation was studied in 15 patients with internal derangement of the temporomandibular joint and 15 patients with no history or clinical signs of mandibular dysfunction. Condylar movement and axis point location were recorded with a sagittal recording device at three separate recording sessions. Lead markers were placed on the skin over the axis and orbital points, and lateral cephalometric radiographs were taken at each session. Analysis of cephalometric and axiographic recordings included both linear and angular measurements. Analysis of the condylar movement pathway revealed greater within-subject reproducibility in the control group for both the right and left condyles (p < 0.0005 and p < 0.0003, respectively). The axis point of condylar rotation in centric relation, as shown by cephalometric analysis, had significantly more within-subject variability in the horizontal plane for the control group (p < 0.003). There was no significant difference between groups for within-subject variability of condylar position in the vertical direction. These findings are consistent with the contemporary concept of centric relation that a vertically stable condyle with a disk interposed against the anterior eminence is capable of functional adaptation in the horizontal plane. The results have implications with regard to treatment and rehabilitation of patients with temporomandibular joint internal derangement.

Adaptation, Physiological↗
PubMed1995

The effectiveness of an interactive instructional context. Principles from the parent-child interaction literature.

In the present study, the effectiveness of embedding a targeted linguistic structure within an interactive instructional context is examined. Ten subjects participated in a communication-games intervention which contained seven interactive elements drawn from the parent-child interaction literature. Ten subjects were assigned to a control group. A comparison of student performance before and after intervention supports the effectiveness of adopting instructional strategies that are consistent with a social-interaction perspective on language development. Qualitative results are presented that illustrate each of the interactional characteristics of the intervention. Implications for practice are discussed.

Child↗
PubMed1990

From drill to practice? A question of generalization.

The current study examined the relationship between hearing-impaired students' (N = 20) ability to write syntactically correct sentences (Noun + Verb + Where and Noun + Verb + Noun) in two formats, one structured and one unstructured. Two sentence-generating tasks were administered as operational measures of the structured format. A story-writing task was administered as an operational measure of the second format. A comparison of student performance across the two formats indicated that students generated more syntactically correct sentences in the structured than the unstructured format. There were very low correlations between the performance on the two formats. The widespread use of structural teaching activities which utilize metalinguistic sentence patterns are discussed. Implications of these findings are discussed in relationship to this widespread practice.

Adolescent↗