A heuristic for the container loading problem: A tertiary-tree-based dynamic space decomposition approach

Increasing fuel costs, post-911 security concerns, and economic globalization provide a strong incentive for container carriers to use available container space more efficiently, thereby minimizing the number of container trips and reducing socio-economic vulnerability. A heuristic algorithm based on a tertiary tree model is proposed to handle the container loading problem (CLP) with weakly heterogeneous boxes. A dynamic space decomposition method based on the tertiary tree structure is developed to partition the remaining container space after a block of homogeneous rectangular boxes is loaded into a container. This decomposition approach, together with an optimal-fitting sequencing and an inner-right-corner-occupying placement rule, permits a holistic loading strategy to pack a container. Comparative studies with existing algorithms and an illustrative example demonstrate the efficiency of this algorithm.     

Use of a scientific microwave apparatus for rapid optimization of reaction conditions in a monomode function and then substrate screening in a multimode function

Recently, a new apparatus has become available, which aims to bring together in one unit the advantages of a monomode and a multimode microwave device. We have assessed the applicability of the apparatus toward rapid optimization of reaction conditions in a monomode function and then substrate screening in a multimode function. We have also probed the effects of differences in microwave absorptivity of reaction mixtures on the product conversions in screening multiple substrates simultaneously in a multimode microwave apparatus. We find that when the microwave absorptivity of a reaction mixture is dictated by the solvent, there is little effect on the heating profile of varying the substrate in a screening run. However, this is not the case when reactions involving non-microwave absorbant solvents are used. In this case the characteristics of the substrate can affect significantly the outcome of the reaction.     

Samarium Diiodide Mediated Reactions in Total Synthesis

Introduced by Henri Kagan more than three decades ago, samarium diiodide (SmI₂) has found increasing application in chemical synthesis. This single‐electron reducing agent has been particularly useful in C? C bond formations, including those found in total synthesis endeavors. This Review highlights selected applications of SmI₂ in total synthesis, with special emphasis on novel transformations and mechanistic considerations. The examples discussed are both illustrative of the power of this reagent in the construction of complex molecules and inspirational for the design of synthetic strategies toward such targets, both natural and designed.     

Pulling Back the Curtain: Uncovering and Changing Students' Perceptions of Scientists

Although there have been numerous scientists‐in‐the‐classroom initiatives in recent years, there is little research that documents whether or not these initiatives make an impact on students. This study examined 27 seventh‐grade and 27 tenth‐grade students' perceptions of scientists before and after a weeklong educational experience on nanotechnology, where students interacted with scientists. The data from this project included student interviews (pre and post intervention), field notes, student stories, and follow‐up interviews conducted 1 year after the project. Results showed that fewer than 10% of participants reported ever interacting with scientists in school settings prior to this project, despite attending schools in areas surrounded by a high density of scientists. Students' perceptions of scientists changed as a result of the project. The implications for science instruction are discussed.     

Indigo Carmine degradation by hypochlorite in aqueous medium monitored by electrospray ionization mass spectrometry

The degradation of the dye Indigo Carmine by hypochlorite in aqueous solution was monitored by electrospray ionization mass spectrometry in the negative ion mode (ESI(—)‐MS). Hypochlorite was highly efficient in removing the color of aqueous solutions of the dye. ESI(—)‐MS monitoring showed that concomitant with the Indigo Carmine consumption two transient species appeared (detected as doubly charged anions) probably formed via a net insertion of two hydroxyl groups at the exocyclic C?C bond followed by the incorporation of two (mainly) or one oxygen atoms at the indolic rings of the dye. Structures of these products were proposed based on the ESI(—)‐MS/MS data and high accuracy mass measurements. These two transient intermediates quickly decomposed, both in the condensed and in the gas phase, to yield mono‐charged anions. Based on these results, a route for the Indigo Carmine degradation by hypochlorite in aqueous solution has been proposed. Copyright © 2007 John Wiley & Sons, Ltd.     

Chemically‐reduced Graphene Oxide Sensor for Dipyrone Quantification in Pharmaceutical Samples Using Amperometric Detection

Dipyrone (metamizole sodium) is one of the most consumed drugs in the world. In this work a novel analytical method was developed for dipyrone sensing. This method involves the amperometric detection on a chemically‐reduced graphene‐oxide (CRGO)‐modified glassy carbon electrode. Raman spectroscopy and scanning electron microscopy revealed the presence of multilayer graphene layers that contributed to the electrocatalytic oxidation of dipyrone and increase in the electroactive area. Advantages of this sensor include elimination of previous separations, solvent extraction, or sample filtration, low detection limit (0.13 μmol L^?1) with a linear range from 48 to 246 μmol L^?1 and adequate recovery values (97–103 %). Applied to commercial pharmaceutical samples, this method showed results ranging from 451 to 541 mg of dipyrone per tablet, which agreed with the expected values. The results obtained by amperometry were compared statistically with the official method recommended by the Brazilian Pharmacopoeia (iodometric method), with no significant differences between them at 95 % confidence level. The proposed method is accurate for the monitoring of sodium dipyrone in pharmaceutical formulations, highlighting the lower reagent consumption and interferences in the analytical process.