Time-Cost Trade-Off Analysis in Some Constrained Assignment Problems

Several variations of two-dimensional (workers x jobs) and three-dimensional (workers x jobs x machines) time- as well as cost-minimizing assignment problems, which arise owing to (i) precedence relations of some form among the jobs or (ii) capacity restrictions on workers/machines imposed by the requirement that the surplus resources have to be fully employed, have been considered in the literature. In this paper, an algorithm is presented for time-cost trade-off analysis which is applicable to any general pair of such constrained problems. The algorithm is also illustrated by a numerical example.     

An extraction study of gallium, indium and thallium using TPASO as an extractant

A method is proposed for the extraction and individual separation of trivalent gallium, indium and thallium from salicylate media using triphenylarsine oxide dissolved in toluene as an extractant. The optimum extraction conditions are evaluated and described. The extracted metal ions are stripped and estimated spectrophotometrically following complexation with 4-(2-pyridylazo) resorcinol. A possible mechanism of the extraction is discussed. The method permits rapid and precise individual separation of gallium (III), indium (III) and thallium (III) and is applicable to the analysis of alloy samples.     

Synthesis of symmetrical 1,5-disubstituted granatanines

A general entry into symmetrical 1,5-disubstituted granatanines that involves an alkylative ring-closure on a 2,6-bis enolate piperidine intermediate is described.     

Development of highly potent inhibitors of the ras-targeting human acyl protein thioesterases based on substrate similarity design

A matter of common sense: A common recognition motif consisting of a negatively charged group five to six bonds away (red) from the (thio)ester functionality (green) and a positively charged tail group ten to twelve bonds away (blue) was identified in two native acyl protein thioesterase?1 (APT1) substrates. This similarity led to the design of potent inhibitors of the Ras-depalmitoylating enzyme APT1.     

Concerted synthesis of a spirobicyclic type-VI beta-turn mimic of Pro-Pro-Pro-NH2

[STRUCTURE: SEE TEXT] A highly concerted strategy for the synthesis of symmetrical type-VI beta-turn mimics was formulated. A proof of concept is presented in the synthesis of a spirobicyclic peptidomimetic of Pro-Pro-Pro-NH2, compound 6. The formation of an unusual adduct that was encountered in the process also is reported. This approach is potentially general for type-VI beta-turn mimics where the i+1 and i+2 residues are identical.     

Separation studies of molybdenum(VI) and rhenium(VII) using TPPO as an extractant

A simple, rapid and reproducible method for the extractive separation of molybdenum(VI) and rhenium(VII) is proposed using triphenylphosphine oxide (TPPO) dissolved in toluene as an extractant. The extractions are carried out from the hydrochloric and hydrobromic acid medium. The extraction of molybdenum is quantitative from 2.54-3.10 M hydrochloric acid and from 3.76-3.98 M hydrobromic acid, and that of rhenium is from 6.78-7.91 M hydrochloric acid. The probable nature of the extractable species is established using log distribution ratio-log concentration plots. The method permits mutual separation of molybdenum(VI) and rhenium(VII) and is applicable for the analysis of alloys and pharmaceutical sample. The detection limits for molybdenum(VI) and rhenium(VII) are 0.8 ppm and 4 ppm respectively.     

Analytical separation of antimony(III) from bismuth(III), lead(II), gallium(III), thallium(III), tellurium(IV) and tin(IV) with cyanex 302

A method is proposed for the separation of antimony(III) (100–400 g) from bismuth(III), lead(II), gallium(III), thallium(III), tellurium(IV) and tin(IV) from an aqueous solution of pH 0.5–1.5 using 8×10^–3–1×10^–2 mol dm^–3 cyanex 302 dissolved in toluene as an extractant. The antimony is stripped from the cyanex phase with water and determined spectrophotometrically with iodide. Various experimental parameters are optimized and the probable 13 stoichiometry of the extracted species is evaluated. The method is applicable to the analysis of alloys and pharmaceutical samples. The separation and determination take only 20 min.     

A Note on Dave's Inventory Model for Deteriorating Items

In this paper an attempt has been made to generalise Dave's results on an inventory model for deteriorating items. He has derived the results for optimal order level and lot size, considering a deterministic constant demand throughout the scheduling period. Here, a variable known demand is taken to show that the optimality conditions for the optimal initial stock do not depend on the nature of the demand. A numerical example is used to illustrate the analysis.     

Improved and Scalable Synthetic Route to the Synthon 17-β-(2-Carboxyethyl)-1,3,5(10)-estratriene: An Important Intermediate in the Synthesis of Bone-Targeting Estrogens

An improved, highly scalable methodology for the multigram-scale preparation of an important synthon, 17-β-(2-carboxyethyl)-1,3,5(10)-estratriene, is described. Previous approaches have failed to provide useful quantities of the analytically pure product because of facile retro-Michael breakdown of the β-alkoxy carbonyl precursors during workup and isolation operations. The synthetic approach described herein has been designed specifically to sidestep this problematic breakdown process. This new scalable method of preparation overcomes a major hurdle in the exploration of structure–activity relationships centered around novel estradiol derivatives with bone-targeting properties and also provides a scalable process for subsequent developmental work.