Hybrid system identification using a structural approach and its model based control: An experimental validation

For implementation of various model based techniques such as in control and fault diagnosis, data-driven identification is key for enabling cheap and rapid development of models of hybrid systems of industrial interest. In the present work, a novel identification method is proposed for a class of hybrid systems which are linear and separable in the discrete variables (that is discrete states and discrete inputs). The method takes cognizance of the fact that the separable structure of the hybrid system constrains the evolution of system dynamics. In particular, the proposed method identifies models corresponding to a certain number of modes, far fewer than the total possible modes of the system. It then generates the models for the remaining modes without any further requirement for input–output data by exploiting the separable structure of the hybrid system. We experimentally validate the method by identifying the model for a three tank benchmark hybrid system followed by model predictive control using the identified model.     

Organocatalytic enantioselective synthesis of β-blockers: (S)-propranolol and (S)-naftopidil

An efficient enantioselective synthesis of β-adrenergic blockers (S)-propranolol and (S)-naftopidil with >98% ee using an l-proline-catalyzed α-aminoxylation of an aldehyde as a key step is described.     

Scaffold hopping for identification of novel D2 antagonist based on 3D pharmacophore modelling of illoperidone analogs

The dopamine D(2) receptor is involved in the etiology of a number of disorders, such as Parkinson's disease, Huntington's Chorea, tardive dyskinesia and schizophrenia. Antagonism of D(2) receptors is implicated in the treatment of various psychiatric disorders. In order to understand essential structural features required for D(2) antagonism, this research article elaborates on the generation of a four-point 3D pharmacophore model which was extracted from a series of 45 novel 3-[[(aryloxy)alkyl]piperidinyl]-1,2-benzisoxazole derivatives. The best pharmacophore model generated consisted of four PRRR features: a positively charged group (P), and three aromatic rings (R). Based on the model generated, a statistically valid 3D-QSAR with good predictability (Q(2) = 0.756) was derived. For the validation of the pharmacophore hypothesis, active compounds were docked against the 3D structure of the D(2) receptor which was constructed through homology modeling. Further, the derived pharmacophore was used as a query to search the Zinc 'clean drug-like' database. Hits retrieved were passed progressively through filters, such as fitness score, predicted activity and docking scores. The resulting hits present new scaffolds with a strong potential for D(2) antagonist.     

A MCMC approach for modeling customer lifetime behavior using the COM‐Poisson distribution

One of the major challenges associated with the measurement of customer lifetime value is selecting an appropriate model for predicting customer future transactions. Among such models, the Pareto/negative binomial distribution (Pareto/NBD) is the most prevalent in noncontractual relationships characterized by latent customer defections; ie, defections are not observed by the firm when they happen. However, this model and its applications have some shortcomings. Firstly, a methodological shortcoming is that the Pareto/NBD, like all lifetime transaction models based on statistical distributions, assumes that the number of transactions by a customer follows a Poisson distribution. However, many applications have an empirical distribution that does not fit a Poisson model. Secondly, a computational concern is that the implementation of Pareto/NBD model presents some estimation challenges specifically related to the numerous evaluation of the Gaussian hypergeometric function. Finally, the model provides 4 parameters as output, which is insufficient to link the individual purchasing behavior to socio‐demographic information and to predict the behavior of new customers. In this paper, we model a customer's lifetime transactions using the Conway‐Maxwell‐Poisson distribution, which is a generalization of the Poisson distribution, offering more flexibility and a better fit to real‐world discrete data. To estimate parameters, we propose a Markov chain Monte Carlo algorithm, which is easy to implement. Use of this Bayesian paradigm provides individual customer estimates, which help link purchase behavior to socio‐demographic characteristics and an opportunity to target individual customers.     

Conformational analysis in diastereoisomer equilibria of square-pyramidal [C5H5(CO)2Mo pyridine-2-imine]PF6 complexes

Synthesis and characterization of sonic new square-pyramidal pyridine-2-imine complexes [C₅,H₅,(CO)₂,MoNC₅,H₄,CX=NCH(R₁)(R₂)]PF₆ with X = CH₃, C₆H₅ and chiral amine, 1-phenyl-isobutylamine and amino acid methyl ester H₂NCH(COOCH₃)(R) with (R) = (CH₂C₆H₅) and (C₂H₅) have been reported. In combination with Mo chirality (R) and (S), mixtures of two diastereoisomeric pairs of enantiomers with racemic amine and amino acids were obtained which were separated by fractional cystallization. The diastereoisomers differ in the chemical shift of most of their ¹H NMR signals and interconvert on heating in acetone-d₆ at 80°C for 80 hr and 40°C for 200 hr. On the basis of three conformational determining effects (i) C-H or C-alkyl of the asymmetric centre eclipses the ligand plane, (ii) MC₅H₅/C₆H₅ attraction and (iii) MC₅H₅/alkyl repulsion in order of decreasing significance, the chemical shifts of the C₅H₅ signals, their differences as well as the diastereoisomer ratio at equilibrium for all the complexes has been rationalised.     

The p53-caspase-2 axis in the cell cycle and DNA damage response

Caspase-2 was discovered almost three decades ago. It was one of the first two mammalian homologs of CED-3, the other being interleukin 1β-converting enzyme (ICE/caspase-1). Despite high similarity with CED-3 and its fly and mammalian counterparts (DRONC and caspase-9, respectively), the function of caspase-2 in apoptosis has remained enigmatic. A number of recent studies suggest that caspase-2 plays an important role in the regulation of p53 in response to cellular stress and DNA damage to prevent the proliferation and accumulation of damaged or aberrant cells. Here, we review these recent observations and their implications in caspase-2-mediated cellular death, senescence, and tumor suppression.Subject terms: Apoptosis, Experimental models of disease     

Synthesis of a pipecolic acid-based bis-amino acid and its assembly into a spiro ladder oligomer

[reaction: see text] The synthesis of a new pipecolic acid-based bis-amino acid building block 1 (and 2) is presented. Assembly of this monomer into a spiro ladder oligomer 3 utilizing solid-phase synthesis followed by in situ activation by dicyclohexylcarbodiimide and N-hydroxysuccinimide has been demonstrated. The structure of oligomer 3, determined in aqueous solution using two-dimensional NMR, reveals that the oligomer forms a left-handed helix and that each monomer unit adopts a chair conformation.     

A [2+2+2]-cyclotrimerization approach for the synthesis of enantiopure isochromans using a carbohydrate derived dialkyne template

An easy access to enantiopure isochromans through cross alkyne trimerization of a glucose derived dialkyne was developed. One of the synthesized isochromans was converted into a novel tricyclic nucleoside by simple transformations.