Specifications Grading has Improved my Courses!

Specifications grading is a way of restoring rigor, motivating students, and saving faculty time as stated in the title of Linda Nilson\u27s book promoting this method. While there are many variations across disciplines, I will present how I am using specifications grading in my Organic Chemistry courses. I label course objectives as essential or non-essential, and students must master these with a quiz score of 80% or greater to obtain the points. Students are allowed multiple attempts to master course objectives

Cometabolic isoterpinolene formation from isolimonene by denitrifying Alcaligenes defragrans

Alcaligenes defragrans strains denitrify on monoterpenes with an unsaturated hydrocarbon structure. a new cometabolic reaction, the formation of isoterpinolene from isolimonene, was detected in cultures that grew on a monoterpene. The biotransformation of isolimonene, a monocyclic monoterpene with a sp(3)-hybridized C1 atom of the menthane skeleton, contrasts with the complete mineralization of monoterpenes with a sp(2)-hybridized C1 atom. This selectivity indicates a demand for a sp(2)-hybridized C1 atom as structural property for monoterpenes that can be oxidized by A. defragrans. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved

Effect of an arginine-to-isoleucine active site mutation on Escherichia coli malate dehydrogenase enzymatic activity

Citric acid cycle enzymes function in an environment with numerous substrate analogues and therefore contain active site residue organizations that confer high substrate specificity. Extensive research into the catalytic mechanism of Escherichia coli malate dehydrogenase (eMDH) has identified arginine81 as being crucial to catalysis. In this investigation, an engineered eMDH having an Ile81 rather than an Arg81 (R81I) was isolated using a hexahistadine (His6) tag. Enzymatic activity of the R81I mutant with respect to malate, lactate, and pyruvate was explored. The R81I mutant did show significant activity toward malate, but did not show significant activity toward lactate or pyruvate. Investigations into an R81F mutant eMDH and an R81W/M85E dimutant eMDH may provide more insight into the eMDH catalytic mechanism

Site-Directed Mutagenesis of Malate Dehydrogenase: A Class Project

Malate dehydrogenase (MDH) is an important enzyme in an organism’s metabolic pathways. MDH is found in almost all living cells and catalyzes the conversion of malate to oxaloacetate which also involves nicotinamide dehydrogenase (NAD) as a coenzyme. A method to study how an enzyme operates is to alter one of its amino acids and compare the activity of the enzyme before and after the mutation. As a class project in Advanced Biochemistry during the spring semester of 2018, we are working as a team to propose and carry out a point-based mutation on MDH

On the peak in the far-infrared conductivity of strongly anisotropic cuprates

We investigate the far-infrared and submillimeter-wave conductivity of electron-doped La_(2-x)Ce_xCuO_4 tilted 1 degree off from the ab-plane. The effective conductivity measured for this tilt angle reveals an intensive peak at finite frequency (\nu ~ 50 cm{-1}) due to a mixing of the in-plane and out-of-plane responses. The peak disappears for the pure in-plane response and transforms to the Drude-like contribution. Comparative analysis of the mixed and the in-plane contributions allows to extract the c-axis conductivity which shows a Josephson plasma resonance at 11.7 cm{-1} in the superconducting state.Comment: 4 pages, 4 figures include

Planar millimeter wave radar frontend for automotive applications

A fully integrated planar sensor for 77 GHz automotive applications is presented. The frontend consists of a transceiver multichip module and an electronically steerable microstrip patch array. The antenna feed network is based on a modified Rotman-lens and connected to the array in a multilayer approach offering higher integration. Furthermore, the frontend comprises a phase lock loop to allow proper frequency-modulated continuous wave (FMCW) radar operation. The latest experimental results verify the functionality of this advanced frontend design featuring automatic cruise control, precrash sensing and cut-in detection. These promising radar measurements give reason to a detailed theoretical investigation of system performance. Employing commercially available MMIC various circuit topologies are compared based on signal-tonoise considerations. Different scenarios for both sequential and parallel lobing hint to more advanced sensor designs and better performance. These improvements strongly depend on the availability of suitable MMIC and reliable packaging technologies. Within our present approach possible future MMIC developments are already considered and, thus, can be easily adapted by the flexible frontend design. Es wird ein integrierter planarer Sensor für 77 GHz Radaranwendungen vorgestellt. Das Frontend besteht aus einem Sende- und Empfangs-Multi-Chip-Modul und einer elektronisch schwenkbaren Antenne. Das Speisenetzwerk der Antenne basiert auf einer modifizierten Rotman- Linse. Für eine kompakte Bauweise sind Antenne und Speisenetzwerk mehrlagig integriert. Weiterhin umfasst das Frontend eine Phasenregelschleife für eine präzise Steuerung des frequenzmodulierten Dauerstrichradars. Die aktuellen Messergebnisse bestätigen die Funktionalit¨at dieses neuartigen Frontend-Designs, das automatische Geschwindigkeitsregelung, Kollisionswarnung sowie Nahbereichsüberwachung ermöglicht. Die Qualität der Messergebnisse hat weiterführende theoretische Untersuchungen über die potenzielle Systemleistungsfähigkeit motiviert. Unter Berücksichtigung von kommerziell erhältlichenMMICs werden verschiedene Schaltungstopologien auf der Grundlage des Signal-Rausch-Verhältnisses verglichen. Sowohl für sequenzielle als auch für parallele Ansteuerung der Antennenkeulen wird eine deutliche Leistungssteigerung ermittelt. Diese Verbesserungen hängen maßgeblich von der Verfügbarkeit geeigneter MMICs und einer zuverlässigen Aufbau- und Verbindungstechnik ab. Das vorliegende Frontend-Konzept kann auf Grund seiner Flexibilität leicht an derlei zukünftige Entwicklungen angepasst werden

Small and large polarons in nickelates, manganites, and cuprates

By comparing the optical conductivities of La_{1.67}Sr_{0.33}NiO_{4} (LSNO), Sr_{1.5}La_{0.5}MnO_4 (SLMO), Nd_2CuO_{4-y} (NCO), and Nd_{1.96}Ce_{0.04}CuO_{4} (NCCO), we have identified a peculiar behavior of polarons in this cuprate family. While in LSNO and SLMO small polarons localize into ordered structures below a transition temperature, in those cuprates the polarons appear to be large, and at low T their binding energy decreases. This reflects into an increase of the polaron radius, which may trigger coherent transport.Comment: File latex, 15 p. incl. 4 Figs. epsf, to appear on the Journal of Superconductivity - Proc. "Stripes 1996" - Roma Dec 199

Affordable Developing Country Server/Workstation Network

We propose a method to provide people of low income in developing countries access to sufficiently current personal computing luxuries.Ope