In this paper, the authors have proposed a method of segmenting gray level images using multiscale morphology. The approach resembles the watershed algorithm in the sense that the dark (respectively ...bright) features which are basically canyons (respectively mountains) on the surface topography of the gray level image are gradually filled (respectively clipped) using multiscale morphological closing (respectively opening) by reconstruction with isotropic structuring element. The algorithm detects valid segments at each scale using three criteria namely growing, merging and saturation. Segments extracted at various scales are integrated in the final result. The algorithm is composed of two passes preceded by a preprocessing step for simplifying small scale details of the image that might cause over-segmentation. In the first pass feature images at various scales are extracted and kept in respective level of morphological towers. In the second pass, potential features contributing to the formation of segments at various scales are detected. Finally the algorithm traces the contours of all such contributing features at various scales. The scheme after its implementation is executed on a set of test images (synthetic as well as real) and the results are compared with those of few other standard methods. A quantitative measure of performance is also formulated for comparing the methods.
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Unlike the hydrocarbon analogs, this first report of enolboration–aldolization of 3,3,3-trifluoropropanoic acid provides essentially pure anti-diastereomers of ...α-trifluoromethyl-β-hydroxy carboxylic acids in 77–90% yields.
Investigations into the transition metal catalyzed aziridination of olefins with Bromamine-T as a new source of nitrene is presented in this account. Comparison of Chloramine-T and Bromamine-T in ...this reaction indicates that the latter is superior as the source of nitrene. Systematic study with several transition metal based catalysts suggests that Cu-halides are the best catalysts. A first report of aziridination under microwave and ultrasound irradiation conditions is also presented. Copper-catalyzed aziridination of methyl cinnamate with Bromamine-T did not proceed at ambient temperature but was effected smoothly under ultrasound irradiation to furnish trans-aziridine selectively, while under microwave irradiation, a mixture of cis and trans isomers. was obtained. It has been demonstrated that aziridination of olefins proceeds smoothly with inexpensive bleaching powder. Preliminary results of Rh-catalyzed benzylic insertion reactions with Bromamine-T are included in this account.
Unnatural amino acids have gained significant attention in protein engineering and drug discovery as they allow the evolution of proteins with enhanced stability and activity. The incorporation of ...unnatural amino acids into proteins offers a rational approach to engineer enzymes for designing efficient biocatalysts that exhibit versatile physicochemical properties and biological functions. This review highlights the biological and synthetic routes of unnatural amino acids to yield a modified protein with altered functionality and their incorporation methods. Unnatural amino acids offer a wide array of applications such as antibody-drug conjugates, probes for change in protein conformation and structure-activity relationships, peptide-based imaging, antimicrobial activities,
etc.
Besides their emerging applications in fundamental and applied science, systemic research is necessary to explore unnatural amino acids with novel side chains that can address the limitations of natural amino acids.
Incorporation of unnatural amino acids into protein offers wide array of applications in fundamental and applied science.
•A systematic examination of the enolboration–aldolization of propanoic acid has been performed.•Chx2BBr/Et3N is as an efficient reagent-base combination for the aldol reaction of propanoic ...acid.•β-Hydroxy-α-methyl carboxylic acids are prepared in high yields and diastereoselectivities.
A systematic examination of enolboration–aldolization of propanoic acid has led to an efficient synthesis of anti-β-hydroxy-α-methyl carboxylic acids in consistently high yields and diastereoselectivities by using B-bromodicyclohexylborane as the enolization reagent and triethylamine as the base.
The enolization temperature overrides all other aspects, including the sterics of the alkyl group of the boron reagent and the alkoxy group of the ester during the enolboration–aldolization of ...phenylacetates. This study has led to the first n-Bu2BOTf-mediated anti-selective aldol reaction of an ester.
This paper presents a method for improving the quality of gray-level images by reducing the effect of noise using multiscale morphology. The underlying concept of the work is to assign progressively ...less importance to features of smaller scales as their possibilities of being noise particles are more. Features at various scales are extracted by means of morphological filtering. The proposed scheme is first illustrated in one dimension. Morphological towers are built to implement the method in two dimensions. The proposed algorithm has been tested on a set of real images corrupted with different types of noise. The results are compared with those of other standard noise removal algorithms based on some standard performance measures. A modification of the method considering noise statistics along with its results are also presented in this paper.
A short, scalable total synthesis of meayamycin is described by an approach that entails a longest linear sequence of 12 steps (22 steps overall) from commercially available chiral pool materials ...(ethyl l-lactate, BocNH-Thr-OH, and d-ribose) and introduces the most straightforward preparation of the right-hand subunit detailed to date. The use of the approach in the divergent synthesis of a representative series of O-acyl analogues is exemplified.
In contrast to methyl phenylacetates, methyl arylacetates do not provide syn-aldols in the dicyclohexylboron triflate/triethylamine (Chx2BOTf/Et3N)-mediated enolboration–aldolization reaction. ...However, a combination of a less bulky boron reagent (dibutylboron triflate, n-Bu2BOTf), a bulky amine (i-Pr2NEt), and ambient temperature is required to obtain syn-aldols from methyl arylacetates. The corresponding anti-aldol products have been synthesized by the enolboration–aldolization of methyl arylacetates in the presence of Chx2BOTf/Et3N at a lower temperature. We report the first example of a complementary syn- and anti-selective enolboration–aldolization of arylacetates.
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