On optimal batch sizing in a multi-stage production system with rework consideration

Recently, Sarker et al. [Sarker, B.R., Jamal, A.M.M., Mondal, S., 2008. Optimal batch sizing in a multi-stage production system with rework consideration. European Journal of Operational Research 184(3) 915–929] presented an EPQ inventory model for a multi-stage manufacturing system with rework process; basically they proposed two operational inventory policies. In the paper, there are some mathematical expressions which are to be corrected. At first, this paper presents the mathematical expressions corrected and the appropriate solution to the numerical example. We also established the closed forms for the optimal total inventory cost, the conditions for which there is an optimal solution, and the mathematical expressions for determining the total additional cost for working with a non optimal solution for both policies that were not given by Sarker et al. (2008).     

Quasi-Newton methods for constrained nonlinear systems: complexity analysis and applications

We address the solution of constrained nonlinear systems by new linesearch quasi-Newton methods. These methods are based on a proper use of the projection map onto the convex constraint set and on a derivative-free and nonmonotone linesearch strategy. The convergence properties of the proposed methods are presented along with a worst-case iteration complexity bound. Several implementations of the proposed scheme are discussed and validated on bound-constrained problems including gas distribution network models. The results reported show that the new methods are very efficient and competitive with an existing affine-scaling procedure.     

On a residual local projection method for the Darcy equation

A new symmetric local projection method built on residual bases (RELP) makes linear equal-order finite element pairs stable for the Darcy problem. The derivation is performed inside a Petrov–Galerkin enriching space approach (PGEM) which indicates parameter-free terms to be added to the Galerkin method without compromising consistency. Velocity and pressure spaces are augmented using solutions of residual dependent local Darcy problems obtained after a static condensation procedure. We prove the method achieves error optimality and indicates a way to recover a locally mass conservative velocity field. Numerical experiments validate theory. To cite this article: L.P. Franca et al., C. R. Acad. Sci. Paris, Ser. I 347 (2009).     

The integrality of the lot size in the basic EOQ and EPQ models: Applications to other production-inventory models

In this paper we present a method to obtain the solution of the classic economic order quantity (EOQ) and economic production quantity (EPQ) models when the lot size must be an integer quantity. This approach is operatively very simple and allows obtaining a rule to discriminate between the situation in which the optimal solution is unique and when there are two optimal solutions. Also, this method is applicable to the resolution of other production-inventory models. We expose some of them and illustrate the use of the method with numerical examples.     

Action of nitric oxide on healthy and inflamed human dental pulp tissue

Irreversible pulpitis has been associated with pain and an increase in the number of pulp inflammatory cells. Based on the action of nitric oxide (NO) elsewhere, NO may possibly participate in the sensory and autonomic innervation of the dental pulp, and may influence local inflammatory responses. The purpose of this study was to analyze normal and inflamed human dental pulp for the presence of NADPH-diaphorase (NADPH-d), as an index of NO system activity. Six non-carious second premolar pulp tissue samples were obtained from young patients who required extractions for orthodontic reasons and six inflamed samples were obtained from symptomatic carious second premolars clinically diagnosed with irreversible pulpitis. Pulp tissue was carefully removed, fixed by immersion in a cold 4% PFA buffered solution for 120min, rinsed in cold phosphate buffer, and quickly-frozen for cryostat sectioning. Pulp tissue was sectioned perpendicularly to the vertical axis of the tooth at 20mum and processed for histochemistry. Sections of each specimen were stained with hematoxylin-eosin and other sections were subjected to histochemical NADPH-d detection. Results indicated the presence of NADPH reactivity within the pulps of both normal and carious teeth. In the normal teeth NADPH-d activity was detected in a small number of vascular endothelial cells and fibroblasts. The inflammatory response of the pulp from carious premolars was detected in connective tissue by the presence of an increased number of fibroblasts, angioblasts and collagen fibers. It was possible to determine the extent of odontoblast reactivity since the odontoblast layer was usually absent in these split-peel preparations. There were no obvious signs of stained pulpal nerve fibers. Overall NADPH-d staining was significantly more intense within inflamed pulp tissues compared to normal healthy samples (Mann-Whitney test, p<0.002). These results suggest that NADPH-d may be used as a marker of inflammatory activity in pulpitis and provide the basis for further studies aiming to clarify the possible functions of NO in human dental pulp in pathophysiological situations.     

Mercury(II) halide complexes with N-donor organic ligands: crystal and molecular structure of HgI2R, R = 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, bipyridine

The synthesis, characterization and single crystal X-ray structure of three compounds of general formula HgI₂R (R = phen[1], dmph [2] and bpy[3]) are presented. The crystal data for the three compounds are: [1], triclinic, space group P (#2) a = 7.902(2), b = 9.479(2), c = 10.002(2) Å, = 91.45(2), = 111.34(2), = 100.82(2)° [2]: monoclinic, space group C2/c (#15) a = 15.670(3), b = 11.640(2), c = 9.730(2) Å, = 114.57(3)° [3]: triclinic, space group P1¯ (#2) a = 9.472(1), b = 9.507(1), c = 9.023(1) Å, = 98.46(1), = 102.89(1), = 119.62(1)°. Compounds [1] and [2] are monomers, with highly distorted tetrahedral environments around Hg. In [3], instead, there is a significant intermolecular I···Hg interaction leading to the formation of softly bound dimers linking two pentacoordinated cations. The structure is compared with related ones in the literature.     

Effect of thermal fluctuations on the coarsening dynamics of 2D hexagonal system

The dynamics of ordering in a 2D hexagonal system was investigated through the Cahn-Hilliard-Cook model. At low thermal noise amplitudes, pinning forces acting on grain boundaries dominate the dynamics and the coarsening evolves logarithmically in time. As noise amplitude increases, fluctuations becomes large enough to unlock dislocations located along grain boundaries and the grain boundary motion is driven by curvature. The grain boundary relaxation leads to a grain structure with Lifshitz's configurations. In this case the dynamic is also logarithmic as a consequence of the pinning of triple points.     

Production of enantiopure β-amino-γ-hydroxyesters from benzoic acid by a selective formal aminohydroxylation

The enantioselective preparation of three protected β-amino-γ-hydroxyesters from benzoic acid is described. The employed synthetic methodology involves the ipso, ortho cis-dihydroxylation of benzoic acid by the mutant strain Ralstonia eutropha B9, followed by a selective halonium induced beta lactamization. Modification of this novel β-lactam structure by the appropriate sequence of reactions allows for the selective preparation of the aforementioned β-amino-γ-hydroxyesters in a diastereodivergent manner. The overall transformation results in a selective formal aminohydroxylation of the diene moiety of the initial cis-cyclohexadienediol. The synthesized products are important building blocks and will allow for the selective preparation of aminoacids, inosamines and alkaloids from benzoic acid.     

Characterization of isomeric 1,2,4-oxadiazolyl-N-methylpyridinium salts by electrospray ionization tandem mass spectrometry

The mass spectrometry behavior of 1,2,4-oxadiazolyl-N-methylpyridinium salts has been investigated. These substances are of current interest as perspective ionic liquids, compounds used as green solvents for synthesis, and for their catalytic properties. The studies have been developed through ESI-MS/MS experiments. The obtained results demonstrate that a readily distinction between the two isomeric classes, 3- N-methylpyridinium- and 5-N-methylpyridinium-1,2,4-oxadiazoles, is possible through ESI-MS/MS experiments. A deeper investigation on the principal fragmentation pathways of characteristic ions has been also developed.     

Levels of cadmium and lead in blood: an application of validated methods in a group of patients with endocrine/metabolic disorders from the Rome area

Lead (Pb) and cadmium (Cd) are environmental pollutants, known to cause adverse health effects in humans even following long-term exposure to low doses. These metals, individually or in combination with other persistent environmental contaminants, have been claimed to have the potential to cause alterations in the function of the endocrine system. Human exposure to Pb and Cd is generally assessed by monitoring their concentrations in blood, taking into account the influence of various factors, such as age, gender, smoking habit, occupation, alcohol consumption, diet and air pollution. Following the phase-out of leaded gasoline in the European Union and improvements in food-packaging and contamination control, a decrease in blood Pb levels of the general population has been observed in several European countries and the USA. We report the preliminary results of a study, performed within the framework of the project “Human Exposure to Xenobiotics with potential Endocrine Activities: Evaluation of Reproductive and Developmental risks”. We measured the concentrations of Cd and Pb in the blood of a group of patients with endocrine/metabolic disorders. The analytical procedures, based on atomic absorption spectrometry, were validated according to the EURACHEM guidelines. The median values and ranges were 0.48 μg l⁻¹ (0.20–1.73 μg l⁻¹) and 21.8 μg l⁻¹ (12.0–65.7 μg l⁻¹) for Cd and Pb, respectively; the Cd levels were significantly higher in smokers. Overall, the concentrations of Cd and Pb found in our series of patients were comparable to levels currently expected in the general population.