Bile acids in asymmetric synthesis and molecular recognition

This account summarizes the progress made in our laboratory towards the development of new uses of naturally occurring bile acids. Applications in Asymmetric Synthesis (intramolecular coupling, and intermolecular reactions) and Molecular Recognition are described with suitable examples.

Fusion of Complementary Online and Offline Strategies for Recognition of Handwritten Kannada Characters

This work describes an online handwritten character recognition system working in combination with an offline recognition system. The online input data is also converted into an offline image, and parallely recognized by both online and offline strategies. Features are proposed for offline recognition and a disambiguation step is employed in the offline system for the samples for which the confidence level of the classifier is low. The outputs are then combined probabilistically resulting in a classifier out-performing both individual systems. Experiments are performed for Kannada, a South Indian Language, over a database of 295 classes. The accuracy of the online recognizer improves by 11% when the combination with offline system is used.

Choice of Classifiers in Hierarchical Recognition of Online Handwritten Kannada and Tamil Aksharas

In this paper, we propose a novel dexterous technique for fast and accurate recognition of online handwritten Kannada and Tamil characters. Based on the primary classifier output and prior knowledge, the best classifier is chosen from set of three classifiers for second stage classification. Prior knowledge is obtained through analysis of the confusion matrix of primary classifier which helped in identifying the multiple sets of confused characters. Further, studies were carried out to check the performance of secondary classifiers in disambiguating among the confusion sets. Using this technique we have achieved an average accuracy of 92.6% for Kannada characters on the MILE lab dataset and 90.2% for Tamil characters on the HP Labs dataset.

DNA recognition by the EcoP15I and EcoPI modification methyltransferases

The DNA-binding properties of the EcoP15I DNA methyltransferase (M . EcoP15I; MTase) were studied using electrophoretic mobility shift assays. We show by molecular size-exclusion chromatography and dimethyl suberimidate crosslinking that M . EcoP15I is a dimer in solution. While M . EcoP15I binds approx. threefold more tightly to its recognition sequence, 5'-CAGCAG-3', than to non-specific sequences in the presence of AdoMet or its analogs, the discrimination between specific and non-specific sequences significantly increases in presence of ATP. These results suggest for the first time a role for ATP in DNA recognition by type-III restriction-modification enzymes. Furthermore, we show that although c2 EcoPI mutant MTases are defective in AdoMet binding, they are still able to bind DNA in a sequence-specific manner.

Machine recognition of printed Kannada text

This paper presents the design of a full fledged OCR system for printed Kannada text. The machine recognition of Kannada characters is difficult due to similarity in the shapes of different characters, script complexity and non-uniqueness in the representation of diacritics. The document image is subject to line segmentation, word segmentation and zone detection. From the zonal information, base characters, vowel modifiers and consonant conjucts are separated. Knowledge based approach is employed for recognizing the base characters. Various features are employed for recognising the characters. These include the coefficients of the Discrete Cosine Transform, Discrete Wavelet Transform and Karhunen-Louve Transform. These features are fed to different classifiers. Structural features are used in the subsequent levels to discriminate confused characters. Use of structural features, increases recognition rate from 93% to 98%. Apart from the classical pattern classification technique of nearest neighbour, Artificial Neural Network (ANN) based classifiers like Back Propogation and Radial Basis Function (RBF) Networks have also been studied. The ANN classifiers are trained in supervised mode using the transform features. Highest recognition rate of 99% is obtained with RBF using second level approximation coefficients of Haar wavelets as the features on presegmented base characters.

DNA recognition by the first tail-to-tail linked distamycin-like oligopeptide dimers

Sequence-specific bidentate binding to double-stranded (ds)-DNA by 'tail-to-tail' linked dimeric, distamycin analogues is described; compared to their monomeric analogues, these dimers exhibit greater affinity and longer binding site size and open up a novel avenue in the design of minor groove binders that overcome the phasing problem.

Evolution of crystallographic texture during deformation of submicron grain size titanium

Evolution of deformation texture in commercially pure titanium with submicron grain size (SMG) was studied using x-ray diffraction (XRD) and electron back scatter diffraction (EBSD) methods. The material was deformed by rolling at room temperature. The deformation mechanism was found to be slip dominated with a pyramidal slip system facilitating plastic deformation. No evidence of tensile or compressive twinning was detected, as generally seen in the case of titanium with conventional microcrystalline grain size. The absence of twinning and the propensity of the pyramidal slip system in the SMG Ti is attributed to the lack of coordinated motion of zonal partial dislocations that leads to twinning.

Texture evolution in an Al-Cu alloy during equal channel angular pressing: the effect of starting microstructure

In this article, the effect of initial microstructure on the texture evolution in 2014 Al alloy during equal channel angular pressing (ECAP) through route A has been reported. Three heat treatment conditions were chosen to generate the initial microstructures, namely (i) the recrystallization anneal (as-received), (ii) solution treatment at 768 K for 1 h, and (iii) solution treatment (768 K for 1 h) plus aging at 468 K for 5 h. Texture analyses were performed using orientation distribution function (ODF) method. The texture strength after ECAP processing was different for the three samples in the order, solutionised > solutionised plus aged condition > as-received. The prominent texture components were A (E) /(A) over bar (E) and B(E)/(B) over bar (E) in addition to several weaker components for the three materials. The strong texture evolution in solutionised condition has been attributed to higher strain hardening of the matrix due to higher amount of solute. In case of the as-received as well as solutionised plus aged alloy, the weaker texture could be due to the strain scattering from extensive precipitate fragmentation and dissolution during ECAP.

Solidification Microstructure and Texture in Grain-refined Titanium alloys

In the present study, solidification microstructure and texture evolution in grain-refined Ti-6Al-4V and γ-TiAl alloys via trace boron addition are compared with their baseline counterparts. Boron addition resulted in dramatic grain refinement by almost an order of magnitude. The texture developed in these alloys is also markedly different from the baseline alloys.