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Topological designing of a series of 4-piperazinylquinazolines as antagonists of platelet-derived growth factor receptor (PDGFR) tyrosine kinase family has been reported using a series of distance-based topological indices. Regression analysis of the data, using maximum R 2 method indicated that inhibitory activity, pIC 50 (μm), in cellular PGDFR phosphorylation assay can be modelled excellently in multi-parametric model. The results are discussed critically using cross-validated parameters.

The lipophilicity of the large set of organic compounds is investigated using distance-based topological indices. The results have shown that molecular lipophilicity can be modeled in multi-parametric model in that W, 1 χ, B, J and logRB along with indicator parameters are involved. The results are discussed critically.

Topological evidences for modelling lipophilicity of a large series of diversed compounds have been provided on the basis of distance-based topological indices. A pool of topological indices along with indicator parameters related to the type of the compounds present in the set of 140 compounds were used for this purpose. The results have shown that topology as well as the type of compounds are the responsible parameters for modelling lipophilicity.

Predictive models for the lipophilicity (logP) of first 25 derivatives of polyacenes are reported. The models are derived from distance-based numerical descriptors which encode information about topology of each compounds in the data set. A new PI-type index called Sadhna index and abbreviated as Sd is introduced for the first time, and its relative correlation potential is established using the results obtained from Wiener (W), Szeged (Sz), first-order Randic connectivity (χ), and Padmakar–Ivan indices. The data show that lipophilicity (logP) is best modelled in bi-parametric model containing PI and Sd indices. The effect due to size, shape, branching, steric and polarity effects on the exhibition of lipophilicity is critically discussed. The predictive ability of the models is discussed on the basis of cross-validation parameters.

Quantitative structure–activity relationship (QSAR) studies on a series of 5-phenyl-3-ureido-1,5-benzodiazepine-2,4-diones has been carried out using a pool of distance-based topological indices. Step-wise regression analysis indicated that penta-parametric regression expression containing Sz, B, Ip1, Ip2 and Ip3 is the most potent and selective for CCK-A affinity. The predictive potential of the model is discussed on the basis of cross-validation parameters as well as by estimating root mean square (RMSR) of the residuals.

A quantitative structure-activity relationship (QSAR) study on binding activity for a series of rodenticides (PAT analogues) to the [(3)H]-mepyramine-labeled H(1) receptor in rat and guinea pig brain is attempted topologically. From the pool of molecular descriptors we, observed that the most significant descriptor is the molecular redundancy index (MRI). Multiple regression analysis gave excellent results with MRI upon introduction of some dummy parameters (indicator parameters). Predictive ability of the proposed models is discussed using cross-validation parameters.

QSAR studies on modelling of biological activity (hCAI) for a series of ureido and thioureido derivatives of aromatic/heterocyclic sulfonamides have been made using a pool of topological indices. Regression analysis of the data showed that excellent results were obtained in multiparametric correlations upon introduction of indicator parameters. The predictive abilities of the models are discussed using cross-validation parameters.

Quantitative structure–activity relationship (QSAR) studies for 2,6-substituted 2,4-diaminopyrido[3,2- d ] pyrimidine analogues of piritrexim (PTX) as inhibitors of dihydrofolate reductase (DHFR) are now made using topological indices. The results have shown that best models are obtained by multiparametric analysis. The predictive potential of the model is discussed on the basis of a cross-validation method.

A quantitative structure--activity relationship (QSAR) study on a series of substituted phenyl analogues 5-[(7-chloro-4-quinolinyl)amino]-3-[(alkylamino)methyl](1,1'-biphenyl)-2-ols and their N(omega)-oxides was made using various combinations of electronic and topological parameters. Several statistically significant regression expressions were obtained using multiple regression analyses. These regressions may be considered as mathematical models for investigating antimalarial activities of the compounds under present study. The antimalarial activity mechanism was investigated using combinations of E(L) and E(H), independently with other molecular descriptors.

Antimalarial activity of a series of sulfonamide derivatives (2,4-diamino-6-quinazoline sulfonamides) was modeled topologically using Wiener ( W )-, and Szeged ( Sz )-indices. The regression analysis of the data has shown that better results are obtained in multiparametric regressions upon introduction of indicator parameters. Predicting ability of the models was tested by r 2 cv values. It was observed that models based on W index gave slightly better results than those in which Sz is involved.

H(3)-receptor antagonists activity in terms of -log K(i) for a series of acylated histamine derivatives was modeled using topological indices, namely negentropy (N), molecular redundancy (MRI), and valence connectivity index ((m)x(v)) indices. Excellent results were obtained in multiple regression analysis upon the introduction of a dummy parameter (indicator parameter). Consistent increase in R(2)(A) value indicated that inspite of observed collinearity the proposed models are significant.

A QSAR analysis has been carried out on the toxicities of 40 mono-substituted nitrobenzenes using recently introduced PI and Sz indices, as well as older molecular redundancy (MRI) and Balaban indices (J). The results have shown that no statistically significant mono-parametric QSAR models are possible. Also, that along with PI, Sz, MRI and J indices are the appropriate parameters to be used in developing multiparametric QSAR models. The toxicities of nitrobenzenes are well predicted by a penta-parametric model consisting of PI, Sz, J, MRI and Ip1 (an indicator parameter taking care of the effect of substitution at 2-position) as the correlating parameters. The predictive ability of the model is determined by a cross-validation method.

The present paper discusses QSAR studies on antimalarial 2,4-diamino-6-quinazoline sulfonamide derivatives using electronic parameters, namely energy of highest occupied molecular orbitals (EH), energy of lowest unoccupied molecular orbitals (EL) and charge density (CD). The results have shown that better results are obtained by introducing dummy parameters (indicator parameter), Ip. Excellent results are obtained when all the four parameters (EH, EL, CD and Ip) are used in correlation analysis.

College curricula undergo changes periodically. This case discusses the various change management strategies employed by the faculty of a midwestern university in implementing incremental and radical change in the business school curriculum. It also analyzes the impact of these changes on student perceptions of the course and of the instructor. Our analysis reveals interesting trends in student responses over a seven year span. We find that students initially resist both types of changes, although the resistance is greater in the case of radical changes. Nevertheless, they eventually view both types of changes as adding value to the curriculum. However, the perception of value addition is temporary, lasting longer for radical change (seven semesters) than for incremental change (five semesters). This suggests that updating of curricula is required on an ongoing basis.

The smectic layer thickness and the switching behavior in MHPOBC have been studied as a function of temperature; SmCα * is a tilted phase and is antiferroelectric at least in the higher-temperature region but becomes ferrielectric with decreasing temperature. The gradual appearance of ferrielectric characteristics in SmCα * suggests the emergence of the Devil's staircase. To explain the antiferroelectricity in SmCα * and SmCA *, two types of molecular interactions are proposed: one is the interaction between the spontaneous polarizations in the neighboring layers which is effective in SmCα *, and the other is the pairing of transverse dipole moments responsible for the antiferroelectricity in SmCA *.

We have measured the temperature dependence of the infrared line shapes of three fundamental vibrations of the ethylidyne species, ≡C–CH3, on the Pt(111) surface. Each of the three line shapes possesses distinctly different properties. The C–C stretch shows the strongest temperature dependence. The full width at half‐maximum (FWHM) varies quadratically with temperature from 6 cm−1 at 82 K to 10 cm−1 at 350 K. The frequency of the C–C stretch shows a linear shift from 1125 cm−1 at 82 K to 1117 cm−1 at 350 K. The symmetric C–H stretch shows a temperature independent frequency of 2883 cm−1 and only a small change in full width from 4.1 cm−1 at 82 K to 5.1 cm−1 at 300 K. The symmetric CH3 bend has an unusually narrow full width of 1.2 cm−1 at 82 K which increases to 2.4 cm−1 at 350 K while its frequency remains constant within the experimental error. The results are discussed in terms of current theories of vibrational line broadening for molecules adsorbed on metal surfaces.