A graph-theoretic approach to modeling metabolic pathways

Summary The metabolic pathways of medazepam, oxazepam, and diazepam were modeled using graph-theoretic transforms which are incorporable into computer-assisted metabolic analysis programs. The information, represented in the form of a graph-theoretic transform kit, which was obtained from these pathways was then used to predict the metabolites of other benzodiazepine compounds. The transform kits gave statistically significant predictions with respect to a statistical method for evaluating the performance of the transform kits.     

An optimization approach for planning daily drayage operations

Daily drayage operations involve moving loaded or empty equipment between customer locations and rail ramps. Our goal is to minimize the cost of daily drayage operations in a region on a given day. Drayage orders are generally pickup and delivery requests with time windows. The repositioning of empty equipment may also be required in order to facilitate loaded movements. The drayage orders are satisfied by a heterogeneous fleet of drivers. Driver routes must satisfy various operational constraints. We present an optimization methodology for finding cost-effective schedules for regional daily drayage operations. The core of the formulation is a set partitioning model whose columns represent routes. Routes are added to the formulation by column generation. We present numerical results for real-world data which demonstrate that our methodology produces low cost solutions in a reasonably short time.     

Luminescence characteristics of several classes of drugs affecting the central nervous system

The excitation, fluorescence and phosphorescence characteristics of 29 compounds of psychopharmacological interest have been studied in ethanol at 77 k. Phosphorescence lifetimes are reported and the low-temperature luminescence spectra discussed. Luminescence characteristics of several important 1,4-benzodiazepines in acidic, basic and neutral solution are reported.     

Assay of 1-hydroxy-3-aminopropylidene-1,1-bisphosphonate and related bisphosphonates in human urine and plasma by high-performance ion chromatography

A method is described for the analysis of 1-hydroxy-3-aminopropylidene-1, 1-bisphosphonate and related bisphosphonates in human urine and plasma. Samples are spiked with 1-hydroxy-5-aminopentylidene-1,1-bisphosphonate as an internal standard and calcium chloride is added to precipitate the bisphosphonates. Following centrifugation the precipitate is redissolved in acetic acid, and the bisphosphonates are separated by high-performance ion chromatography on a Dionex AS7 column using nitric acid as mobile phase. The bisphosphonates are oxidised to orthophosphate using post-column addition of ammonium persulphate and this is followed by post-column reaction with molybdenum-ascorbate to yield the phosphomolybdate chromophore which is detected at 820 nm. A detection limit of 10 ng/ml is possible.     

Structure and Kinetics of Desolvation of 2-Hexanone Inclusion Compounds of the Hexapedal Hosts, Hexakis(3-hydroxy-3,3-diphenyl-2-propynyl)benzene and 1,2,3,5,6,7-Hexakis(3-hydroxy-3,3-diphenyl-2-propynyl)naphthalene

The 2-hexanone inclusion compounds of hexakis(3-hydroxy-3,3-diphenyl-2-propynyl)benzene and 1,2,3,5,6,7-hexakis(3-hydroxy-3,3-diphenyl-2-propynyl)naphthalene have been prepared and characterised by single crystal X-ray diffraction and thermal analysis. The kinetic parameters and mechanisms for the desolvation reaction have also been determined for both compounds.     

Potential carry-over effect in the measurement of induced loudness reduction

The majority of studies on induced loudness reduction (ILR) use an experimental paradigm that results in an underestimation of the amount of ILR. Most of those studies utilize loudness matches between tones of two different frequencies (a test tone and a comparison tone) with (experimental condition) and without (baseline condition) an inducer tone at the test frequency. The change in level of the comparison tone between the baseline and experimental conditions is the amount of ILR. In those experiments, the level of the comparison tone in the baseline condition tends to be substantially higher (often about 10 dB) than in the experimental condition. Because of this level difference, exposure to the baseline condition immediately prior to the experimental condition causes unintended ILR for the comparison tone. In this study, the delay between the baseline and experimental conditions was varied and it was determined that the amount of ILR is underestimated by about 30% and the variability is increased when the experimental condition is run immediately after the baseline condition. A second experiment using a Békésy-tracking procedure showed that ILR maximizes rapidly upon exposure to an inducer and decays over the course of several minutes after the inducer is removed.     

A good foundation for number learning for five-year-olds? An evaluation of the English Early Learning ‘Numbers’ Goal in the light of research

This article sets out to evaluate the English Early Years Foundation Stage Goal for Numbers, in relation to research evidence. The Goal, which sets out to provide ‘a good foundation in mathematics’, has greater breadth of content and higher levels of difficulty than previous versions. Research suggests that the additional expectations are unachievable by the majority of rising fives, but that a more effective foundation to ensure progress and prevent later difficulties would prioritise number sense with numbers to 10, including subitising, numeral comprehension, relative number size, one more/less than and part–whole relationships.     

Cyclohexanone inclusion compounds of related multipedal hosts

The structures of the cyclohexanone inclusion compounds of (1) hexakis (3-hydroxy-3, 3-diphenyl-2-propynyl) benzene (H1) (triclinic, P1¯, a = 8.957(4), b = 16.69(1), c = 17.201(4) Å, = 93.82(3), = 97.61(3), and = 93.13(5)°); (2) 1,2,3,5,6,7-hexakis(3-hydroxy-3,3-diphenyl-2-propynyl)naphthalene (H2) (monoclinic, P2₁/n, a = 9.444(5), b = 18.353(5), c = 31.59(1) Å, and = 92.18(3)°) and (3) tetra(3-hydroxy-3,3-diphenyl-2-propynyl)ethylene (H3) (triclinic, P1¯, a = 14.208(2), b = 14.710(4), c = 17.915(2) Å, = 91.06(1), = 89.98(1), and = 110.60(2)°) have been determined. A second cyclohexanone inclusion compound with H1 with a different host to guest ratio (4: triclinic, P1¯, a = 9.512(2), b = 15.327(3),c = 16.151(3) Å, = 114.89(2), = 95.19(2), and = 102.67(2)°) was obtained from a 50:50 molar solution of cyclohexanone and 1,4-dioxane, which confirms the selectivity of this host for compounds with carbonyl functional groups. The thermal analysis results of all these cyclohexanone inclusion compounds are reported.