Crystallographic evidence for unintended benzisothiazolinone 1‐oxide formation from benzothiazinones through oxidation

1,3‐Benzothiazin‐4‐ones (BTZs) are a promising new class of drugs with activity against Mycobacterium tuberculosis, which have already reached clinical trials. A product obtained in low yield upon treatment of 8‐nitro‐2‐(piperidin‐1‐yl)‐6‐(trifluoromethyl)‐4H‐benzothiazin‐4‐one with 3‐chloroperbenzoic acid, in analogy to a literature report describing the formation of sulfoxide and sulfone derived from BTZ043 [Tiwari et al. (2015). ACS Med. Chem. Lett. 6 , 128–133], is a ring‐contracted benzisothiazolinone (BIT) 1‐oxide, namely, 7‐nitro‐2‐(piperidine‐1‐carbonyl)‐5‐(trifluoromethyl)benzo[d]isothiazol‐3(2H)‐one 1‐oxide, C₁₄H₁₂F₃N₃O₅S, as revealed by X‐ray crystallography. Single‐crystal X‐ray analysis of the oxidation product originally assigned as BTZ043 sulfone provides clear evidence that the structure of the purported BTZ043 sulfone is likewise the corresponding BIT 1‐oxide, namely, 2‐[(S)‐2‐methyl‐1,4‐dioxa‐8‐azaspiro[4.5]decane‐8‐carbonyl]‐7‐nitro‐5‐(trifluoromethyl)benzo[d]isothiazol‐3(2H)‐one 1‐oxide, C₁₇H₁₆F₃N₃O₇S. A possible mechanism for the ring contraction affording the BIT 1‐oxides instead of the anticipated constitutionally isomeric BTZ sulfones and antimycobacterial activities thereof are discussed.     

Proteome-Based Profiling of Hypercellulase-Producing Strains Developed Through Interspecific Protoplast Fusion Between Aspergillus nidulans and Aspergillus tubingensis

Thirty heterokaryons, formed by protoplast fusion of Aspergillus nidulans and Aspergillus tubingensis, were selected on the basis of their ability to grow on 2-deoxyglucose (0.2 %, w/v) and intermediate spore color. These heterokaryons were studied for cellulase production using shake flask and solid substrate cultures at 40 °C. Fusants 51 and 28 exhibited appreciably higher levels of endoglucanase, cellobiohydrolase, β-glucosidase, and FPase activities when compared with parental strains. Employing proteomic-based approaches, the differential expression of proteins in secretome of fusants and parental strains were analyzed using two-dimensional electrophoresis. The expression of some of the proteins in the fusants was found to be up/downregulated. The upregulated proteins in the fusant 51 were identified by liquid chromatography–mass spectroscopy as endoxylanase, endochitinase, β-glucosidase, as well as hypothetical proteins. The cellulases produced by fusants 28 and 51 showed improved saccharification of alkali treated rice straw when compared with the parental strains.     

Nanoparticle assembled microcapsules for application as pH and ammonia sensor

The encapsulation of molecular probes in a suitable nanostructured matrix can be exploited to alter their optical properties and robustness for fabricating efficient chemical sensors. Despite high sensitivity, simplicity, selectivity and cost effectiveness, the photo-destruction and photo-bleaching are the serious concerns while utilizing molecular probes. Herein we demonstrate that hydroxy pyrene trisulfonate (HPTS), a pH sensitive molecular probe, when encapsulated in a microcapsule structure prepared via the assembly of silica nanoparticles mediated by poly-L-lysine and trisodium citrate, provides a robust sensing material for pH sensing under the physiological conditions. The temporal evolution under continuous irradiation indicates that the fluorophore inside the silica microcapsule is extraordinarily photostable. The fluorescence intensity alternation at dual excitation facilitates for a ratiometic sensing of the pH, however, the fluorescence lifetime is insensitive to hydrogen ion concentration. The sensing scheme is found to be robust, fast and simple for the measurement of pH in the range 5.8-8.0, and can be successfully applied for the determination of ammonia in the concentration range 0-1.2 mM, which is important for aquatic life and the environment.     

Capillary electrophoresis microchip for direct amperometric detection of DNA fragments

Detection and quantitation of nucleic acids have gained much importance in the last couple of decades, especially in the post-human genome project era. Such processes are tedious, time consuming and require expensive reagents and equipment. Therefore, in the present study, we demonstrated a simple process for the separation and analysis of small DNA fragments using capillary electrophoretic amperometric detection on an inexpensive disposable glass microchip. The device used polydimethylsiloxane engraved microchannel and Au/Ti in-channel microelectrodes for sample detection. The DNA fragments were separated under low electric field (20 V/cm) for improved detection sensitivity and to retain the biomolecules in their native conformation. With a low sample requirement (as low as 1 μL) and high reproducibility, the proposed microchip device was successful in resolution and detection of DNA fragments of various lengths.     

On generalizations of network design problems with degree bounds

Iterative rounding and relaxation have arguably become the method of choice in dealing with unconstrained and constrained network design problems. In this paper we extend the scope of the iterative relaxation method in two directions: (1) by handling more complex degree constraints in the minimum spanning tree problem (namely laminar crossing spanning tree), and (2) by incorporating ‘degree bounds’ in other combinatorial optimization problems such as matroid intersection and lattice polyhedra. We give new or improved approximation algorithms, hardness results, and integrality gaps for these problems. Our main result is a (1, b + O(log n))-approximation algorithm for the minimum crossing spanning tree (MCST) problem with laminar degree constraints. The laminar MCST problem is a natural generalization of the well-studied bounded-degree MST, and is a special case of general crossing spanning tree. We give an additive Ω(log ^c m) hardness of approximation for general MCST, even in the absence of costs (c > 0 is a fixed constant, and m is the number of degree constraints). This also leads to a multiplicative Ω(log ^c m) hardness of approximation for the robust k-median problem (Anthony et al. in Math Oper Res 35:79–101, 2010), improving over the previously known factor 2 hardness. We then consider the crossing contra-polymatroid intersection problem and obtain a (2, 2b + Δ ? 1)-approximation algorithm, where Δ is the maximum element frequency. This models for example the degree-bounded spanning-set intersection in two matroids. Finally, we introduce the crossing latticep olyhedron problem, and obtain a (1, b + 2Δ ? 1) approximation algorithm under certain condition. This result provides a unified framework and common generalization of various problems studied previously, such as degree bounded matroids.     

Estimation of robot states with poisson process based on EKF approximate of Kushner filter: a completely coordinate free Lie group approach

Meccanica - In this paper, a Lie coordinate-free torque based Euler–Lagrange equations of motion are developed for a 3-D link (3-DOF) robot. Intentional torque and jerky torque...     

Tree-Based Threshold-Sensitive Energy-Efficient Routing Approach For Wireless Sensor Networks

Wireless Personal Communications - The widespread use of wireless sensor devices and their advancements in terms of size, deployment cost and user friendly interface have given rise to many...