Receiver operating characteristic analysis for the selection of threshold values for detection of capping in powder compression

The acoustic emission (AE) energy obtained from compressing lactose powder to form pharmaceutical tablets was chosen for condition monitoring of the tablets. The method used was based on the setting of an AE energy decision threshold such that problems of tablet capping and lamination were successfully identified. Capping and lamination are the most common types of problem that can occur in tablets manufacturing using a powder compression process. To assess the performance of a classifier, use was made of a receiver operating characteristic curve (ROC) obtained by plotting the correct detection probability against the false alarm probability based on AE energy distributions for capped and non-capped tablets. The area under the ROC curve, referred to as the AUC, determines the level of competency of the classifier. A value of 0.5 suggests a mere hazarding of guesses whilst a value of 1 indicates correct classification every time. The AE energy approach for tablet capping monitoring gives an AUC value of 0.96, thereby suggesting the possibility of a highly accurate classifier. With the assumption that penalties for false alarm and missed detection are equally severe, using the graphical method of expected penalty cost (EPC), the optimal AE energy decision threshold was established to be 1.2x10(8) units, at which the maximum correct capping detection rate of 95% was achieved. The paper also explains how a decision threshold can be obtained when the two penalties are not equal.     

Soliton compression and pulse-train generation by use of microchip Q-switched pulses in Bragg gratings

Pulse compression and pulse-train generation are demonstrated by use of kilowatt 580 ps pulses generated by a compact (15 cm x 3 cm x 3 cm) microchip Q-switched laser followed by a fiber Bragg grating. A 12-fold pulse compression to 45 ps with five times peak power enhancement is achieved at 1.4 kW through soliton effect compression in the fiber grating. At 2.5 kW, modulational instability leads to a train of high-contrast sub-100 ps pulses. These demonstrations take advantage of the ultrastrong dispersion at frequencies close to the edge of the photonic bandgap. Experimental results are discussed in the context of the nonlinear Schr?dinger equation and are compared with simulations of the nonlinear coupled-mode equations.     

Cladioxazole: a novel sesquiterpene from a marine soft coral of genus Cladiella

Chemical investigations on the methanolic extract of Cladiella species, collected from Andaman Island, India, yielded a novel sesquiterpene, cladioxazole (1). Its structure was established with the aid of extensive spectral studies.     

Enantioselective synthesis of "quaternary" 1,4-benzodiazepin-2-one scaffolds via memory of chirality

Glycine-derived 1,4-benzodiazepine-2-ones such as diazepam are chiral by virtue of the boat-shaped conformation of the diazepine ring and exist as a racemic mixture of conformational enantiomers. However, the presence of a chiral center at C-3 of the benzodiazepine perturbs this equilibrium and preferentially stabilizes one ring conformer. We report that N-i-Pr 1,4-benzodiazepine-2-ones derived from (S)-Ala and (S)-Phe can be deprotonated and alkylated in 86-99% ee, despite the fact that the original chiral center is destroyed in the deprotonation step. We attribute this highly enantioselective alkylation to the chiral memory of the benzodiazepine ring. This protocol provides easy access to the previously unexplored "quaternary" 1,4-benzodiazepine-2-ones.     

The structural dynamics of the American five-string banjo

The American five-string banjo is unique among musical instruments in that many significant parameters that effect tone are easily adjusted. This is probably why so many banjo players fiddle with their banjo. The instrument is a combination of canonical vibrating systems (strings, and a circular membrane) and therefore more amenable to analysis and modeling than most other musical instruments (e.g., the violin). Such an analysis is presented here. The model is a harmonically driven string which excites the other strings and a membrane under tension, causing the membrane to radiate sound. Three figures-of-merit, FOMs, are assumed. They are loudness, brightness, and decay of the sound. The effects of a number of parameters on the proposed FOMs are investigated. Among these are the loss factor and tension of the membrane, the mass of the bridge, and the location on the string of the excitation. It is noted that the calculated effects of the changes agree with generally accepted setup practices.     

A survey of dynamically-adaptive grids in the numerical solution of partial differential equations

The construction of dynamically-adaptive curvilinear coordinate systems based on numerical grid generation and the use thereof in the numerical solution of partial differential equations is surveyed, and correlations are made among the various approaches. These adaptive grids are coupled with the physical solution being done on the grid so that the grid points continually move in the course of the solution in order to resolve developing gradients, or higher variations, in the solution. Particular attention is given to systems using elliptic grid generation based on variational principles. It is noted that dynamic grid adaption can remove the oscillations common when strong gradients occur on fixed grids, and that it appears that when the grid adapts to the solution most numerical solution algorithms work well. Particular applications in computational fluid dynamics and heat transfer are noted.     

CalciumK X-ray spectra produced by oxygen,alpha-particle,and proton bombardment

Kα andKβ X-rays of calcium were produced by bombarding a thick calcium wafer with oxygen, helium and hydrogen ions. These reactions produce a substantial amount of inner shell ionization. TheK X-ray spectra contain X-ray lines from calcium which emanate from initial states with a varying degree ofK orL shell vacancies. The initial configurations were assigned on the basis of Hartree-Fock-Slater calculated energies. Related intensity ratio of1s→2p (Kα) transitions and of1s→3p (Kβ) transitions of H plus Ca, He plus Ca and O plus Ca were obtained. In addition to observing many new transitions due to multipleK and/or multipleL shell vacancies, energy shifts relative to the H plus Ca spectrum were observed in the O plus Ca spectrum due toM shell vacancies.