Combining very large scale and ILP based neighborhoods for a two-level location problem

In this paper we tackle a generalization of the Single Source Capacitated Facility Location Problem in which two sets of facilities, called intermediate level and upper level facilities, have to be located; the dimensioning of the intermediate set, the assignment of clients to intermediate level facilities, and of intermediate level facilities to upper level facilities, must be optimized, as well. Such problem arises, for instance, in telecommunication network design: in fact, in hierarchical networks the traffic arising at client nodes often have to be routed through different kinds of facility nodes, which provide different services. We propose a heuristic approach, based on very large scale neighborhood search to tackle the problem, in which both ad hoc algorithms and general purpose solvers are applied to explore the search space. We report on experimental results using datasets from the capacitated location literature. Such results show that the approach is promising and that Integer Linear Programming based neighborhoods are significantly effective.     

Choice of item pricing feedback schemes for multiple unit reverse combinatorial auctions

Recently, interest in combinatorial auctions has extended to include trade in multiple units of heterogeneous items. Combinatorial bidding is complex and iterative auctions are used to allow bidders to sequentially express their preferences with the aid of auction market information provided in the form of price feedbacks. There are different competing designs for the provision of item price feedbacks; however, most of these have not been thoroughly studied for multiple unit combinatorial auctions. This paper focuses on addressing this gap by evaluating several feedback schemes or algorithms in the context of multiple unit auctions. We numerically evaluate these algorithms under different scenarios that vary in bidder package selection strategies and in the degree of competition. We observe that auction outcomes are best when bidders use a naïve bidding strategy and competition is strong. Performance deteriorates significantly when bidders strategically select packages to maximize their profit. Finally, the performances of some algorithms are more sensitive to strategic bidding than others.     

Brønsted/Lewis acid synergy in dealuminated HY zeolite: a combined solid-state NMR and theoretical calculation study

The Br?nsted/Lewis acid synergy in dealuminated HY zeolite has been studied using solid-state NMR and density function theory (DFT) calculation. The 1H double quantum magic-angle spinning (DQ-MAS) NMR results have revealed, for the first time, the detailed spatial proximities of Lewis and Br?nsted acid sites. The results from 13C NMR of adsorbed acetone as well as DFT calculation demonstrated that the Br?nsted/Lewis acid synergy considerably enhanced the Br?nsted acid strength of dealuminated HY zeolite. Two types of Br?nsted acid sites (with enhanced acidity) in close proximity to extra-framework aluminum (EFAL) species were identified in the dealuminated HY zeolite. The NMR and DFT calculation results further revealed the detailed structures of EFAL species and the mechanism of Br?nsted/Lewis acid synergy. Extra-framework Al(OH)3 and Al(OH)2+ species in the supercage cage and Al(OH)2+ species in the sodalite cage are the preferred Lewis acid sites. Moreover, it is the coordination of the EFAL species to the oxygen atom nearest the framework aluminum that leads to the enhanced acidity of dealuminated HY zeolite though there is no direct interaction (such as the hydrogen-bonding) between the EFAL species and the Br?nsted acid sites. All these findings are expected to be important in understanding the roles of Lewis acid and its synergy with the Br?nsted acid in numerous zeolite-mediated hydrocarbon reactions.     

Relationship between 1H chemical shifts of deuterated pyridinium ions and Brønsted acid strength of solid acids

Deuterated pyridine (pyridine-d5) is one of the NMR probe molecules widely used for determination of acid strength of solid catalysts. However, the correlation between the 1H chemical shift of adsorbed pyridine-d5 and the Br?nsted acid strength of solid acids has rarely been investigated. Here, an 8T zeolite model with different Si-H bond lengths is used to represent the Br?nsted acid sites with different strengths (from weak, strong, to superacid) and to predict the pyridine adsorption structure as well as the 1H chemical shift. The theoretical calculation suggests that a smaller 1H chemical shift of the pyridinium ions on the solid acids indicates a stronger acid strength. On the basis of the results of theoretical calculations, a linear correlation between the pyridine-d5 1H chemical shift and the proton affinity (PA) of the Br?nsted acid site has been derived. In combination with the available 1H MAS NMR experimental data, we conclude that pyridine-d5 can be used as a scale to characterize the solid acid strength.     

Selective reduction of carboxylic acid derivatives by catalytic hydrosilylation

In the last decade, an increasing number of useful catalytic reductions of carboxylic acid derivatives with hydrosilanes have been developed. Notably, the combination of an appropriate silane and catalyst enables unprecedented chemoselectivity that is not possible with traditional organometallic hydrides or hydrogenation catalysts. For example, amides and esters can be reduced preferentially in the presence of ketones or even aldehydes. We believe that catalytic hydrosilylations will be used more often in the future in challenging organic syntheses, as the reaction procedures are straightforward, and the reactivity of the silane can be fine-tuned. So far, the synthetic potential of these processes has clearly been underestimated. They even hold promise for industrial applications, as inexpensive and readily available silanes, such as polymethylhydrosiloxane, offer useful possibilities on a larger scale.     

Evaluation of the suitability of archival Bouin-fixed paraffin-embedded tissue specimens to proteomic investigation

Bouin's solution has been used for over a century as a common fixative in several pathology laboratories worldwide. Therefore, a considerable number of Bouin-fixed paraffin-embedded (BFPE) tumor samples of various origin are available in hospital repositories as a powerful information mine for clinical investigations. To date, however, such archived tissues have not been subjected to a systematic study aimed to evaluate their potential use in proteomics. In this report, we investigated whether archival BFPE tissue specimens could be exploited for proteomic studies, upon application of protein extraction and proteomic analysis methods previously optimized for formalin-fixed samples. As a result, gastric BFPE protein extracts exhibited poor suitability for 2D-PAGE analysis, whereas over 300 unique proteins could be successfully detected when extracts were subjected to SDS-PAGE followed by LC-MS/MS (GeLC-MS/MS). Among these, several known markers for gastric cancer and normal gastric functionality were identified, indicative of biological and clinical significance of proteomic data mined from BFPE tissues. A quantitative and qualitative comparison of FFPE and BFPE tissue proteomes was also performed, and results are reported. In conclusion, we demonstrated that BFPE specimens can be analyzed by means of a proteomic approach such as GeLC-MS/MS. Although considerable molecular biases and technical constraints exist, BFPE tissue archives can be fruitfully exploited for gathering proteomic data from particularly precious samples.     

Calorimetric study of calcium aluminate cement blended with flue gas desulfurization gypsum

The use of by-product gypsum is an important alternative in concrete design. In present experiment, conduction calorimetry was applied to investigate the early hydration of calcium aluminate cement (CAC)/flue gas desulfurization (FGD) gypsum paste, supplemented with the determination of setting times and analysis of hydrates by X-ray diffraction (XRD). It was found that different profiles of heat evolution rate were presented depending on the CAC/FGD gypsum ratio. Two distinct exothermic peaks, associating with CAC hydration and ettringite formation respectively, appeared when the FGD gypsum content was less than 20%. Hydrate barrier mechanism was introduced to explain the difference in induction periods of the pastes with or without FGD gypsum. It is concluded that the blending of FGD gypsum accelerates the hydration of CAC for the quick formation of ettringite and generates greater hydration heat from per gram of pure CAC for the high exothermic effect of ettringite formation. The dissolution and diffusion of gypsum plays an important role of reacting controller during the hydrations of the pastes with FGD gypsum. The modified hydration process and mechanism in this case is well visualized by means of calorimetry.     

Spin-to-orbital angular momentum conversion in spin Hall effect of light

From the viewpoint of classical electrodynamics, we identify the role of spin-to-orbital angular momentum conversion in spin Hall effect (SHE) of light. We introduce a distinct separation between spin and orbital angular momenta to clarify the spin–orbital interaction in conventional beam refraction. We demonstrate that the refractive index gradient can enhance or suppress the spin-to-orbital angular momentum conversion, and thus can control the SHE of light. We suggest that the metamaterial whose refractive index can be tailored arbitrarily may become a good candidate for amplifying or eliminating the SHE of light, and by properly facilitating the spin-to-orbital angular momentum conversion the SHE may be enhanced dramatically. The transverse spatial shifts governed by the spin-to-orbital angular momentum conversion, provide us a clear physical picture to clarify the role of refractive index gradient in the SHE of light. These findings provide a pathway for modulating the SHE of light and can be extrapolated to other physical systems.