Kettering University

About: Kettering University is a education organization based out in Flint, Michigan, United States. It is known for research contribution in the topics: RNA & Antigen. The organization has 6842 authors who have published 7689 publications receiving 337503 citations. The organization is also known as: GMI Engineering & Management Institute & General Motors Institute.

A Modular-Designed Three-Phase High-Efficiency High-Power-Density EV Battery Charger Using Dual/Triple-Phase-Shift Control

Abstract: In this paper, an enhancement-mode GaN high-electron mobility transistor (HEMT)-based 7.2-kW single-phase charger was built. Connecting three such single-phase modules to the three-phase grid, respectively, generates a three-phase ∼22-kW charger with the $>{\text{97}}\% $ efficiency and $>{\text{3.3}}-{\rm{kW}/ \rm{L}}$ power density, superior to present Si-device-based chargers. In addition to GaN HEMTs with fast-switching transitions yielding high efficiency, the proposed charger employs the dc/dc stage to control the power factor and power delivery simultaneously, yielding little dc-bus capacitance and thereby high power density. To secure the soft switching for all switches within full voltage and power ranges, a variable switching frequency control with dual phase shifts was adopted at high power, and a triple phase shift was employed to improve the power factor at low power. Both control strategies accommodated the wide input range (80–260 VAC) and output range (200–450 VDC). A closed-loop control for the three-phase charger was realized to minimize the output current ripple and balance the power among three single-phase modules. Experimental results validated this design.

Chondrosarcoma of the head and neck

Abstract: Summary Eighteen primary chondrosarcomas of the head and neck were reviewed at the Memorial and James Ewing Hospitals. Twelve patients presented with a painless mass arising within the oral cavity. Headache, blurred vision, proptosis, swelling, and numbness of the face were the other prominent complaints. The maxilla was involved in ten of the eighteen patients; the lower jaw was involved in four of the other cases studied. Surgery was the prime method of treatment in all cases; additional surgery and radiation therapy were employed for recurrent tumor. Eight of the eighteen patients were alive and free of disease more than five years. Tumor recurrence at or near the region of primary resection was the major factor leading to the patient's death. A comparison of lesions arising in the axial skeletal system with lesions originating in the head and neck indicated that lesions of the head and neck occur in much younger persons and that these tumors are not as aggressive.

CD28 of T lymphocytes associates with phosphatidylinositol 3-kinase.

Abstract: T lymphocyte activation requires recognition of antigen by the antigen specific TCR as well as second co-stimulatory signals. This recognition event results in the activation of non-TCR linked protein tyrosine kinases (PTKs). The mechanism of co-stimulation of T cells is unknown except for the involvement of PTKs. The T cell surface molecule CD28 is effective in delivering co-stimulatory signals and prevents T cell anergy by inducing T cell proliferation in TCR stimulated T cells, primarily due to an increase in IL-2 production. The mechanism by which CD28 mediates this effect is currently unknown. Some conventional receptor molecules possess intrinsic tyrosine kinase and as a consequence of cross-linking or ligand binding, phosphorylate numerous tyrosines within their cytoplasmic tail, leading these tyrosines to become 'activated' and bind cytoplasmic effector molecules possessing Src homology 2 domains which specifically recognize phosphorylated tyrosines. One such cytoplasmic effector molecule is the phosphatidylinositol-3-phosphate kinase (PI3 kinase) which recognizes the motif phosphotyrosine-methione/valine-X-methionine (X being any amino acid) within the cytoplasmic tails of numerous receptor tyrosine kinases. As CD28 contains a copy of the PI3 kinase binding motif within its cytoplasmic tail, we investigated CD28 signaling and PI3 kinase activation. Here we demonstrate using the Jurkat cell line that CD28 becomes tyrosine phosphorylated following CD28 cross-linking and associates with PI3 kinase. Furthermore, a synthetic peptide representing the YM/VXM motif within the cytoplasmic tail of CD28 also interacts with PI3 kinase only when the tyrosine is phosphorylated.(ABSTRACT TRUNCATED AT 250 WORDS)

Discovery through total synthesis: a retrospective on the himastatin problem.

Abstract: A total synthesis of a structure proposed for himastatin was accomplished. The non-identity of the fully synthetic material with himastatin necessitated a revision of the assigned structure. Confirmation of the revised stereostructure was subsequently confirmed through total synthesis. Among the achievements during this effort were i) stereospecific routes to both anti-cis and syn-cis pyrrolindoline substructures; ii) a practical synthesis to 5-hydroxypiperazic acid in enantiomerically pure form; iii) a Stille coupling leading to a complex bi-indole moiety, and iv) efficient protecting group management throughout the evolving depsipeptide domain. The outlines for a biological pharmacophore have been delineated. The alternating D- and L-substituents in the 6-mer as well as the biaryl linkage connecting the two identical subunits are critical for maintaining biological activity. This pattern is simulated in another antibiotic, and suggests a possible structural trend for future SAR investigations.