A compact cryogenic configurable slit unit for a multi-object infrared spectrograph:Design and Development of a prototype at TIFR

We present a cryogenic configurable slit unit (CSU) for a multi object infrared spectrograph with an effective field of view of 9.1 arcmin x 9.1 arcmin that was completely conceived and designed in the laboratory at TIFR. Several components of the CSU including the controller for the commercially procured piezo-walkers, controlled loop position sensing mechanism using digital slide callipers and a cryogenic test facility for the assembled prototype were also developed in-house. The principle of the CSU involves division of the field of view of the spectrometer into contiguous and parallel spatial bands, each one associated with two opposite sliding metal bars that can be positioned to create a slit needed to make spectroscopic observations of one astronomical object. A three-slit prototype of the newly designed CSU was built and tested extensively at ambient and cryogenic temperatures. The performance of the CSU was found to be as per specifications.Comment: 7 pages, Accepted for publication in the Journal of Astronomical Instrumentatio

Mapping Arginase Expression with ¹⁸F-Fluorinated Late-Generation Arginase Inhibitors Derived from Quaternary α-Amino Acids

Arginase hydrolyzes L-arginine and influences levels of polyamines and nitric oxide. Arginase overexpression is associated with inflammation and tumorigenesis. Thus, radiolabeled arginase inhibitors may be suitable PET tracers for staging arginase-related pathophysiologies. We report the synthesis and evaluation of 2 radiolabeled arginase inhibitors, 18F-FMARS and 18F-FBMARS, developed from α-substituted-2-amino-6-boronohexanoic acid derivatives. Methods: Arylboronic ester-derived precursors were radiolabeled via copper-mediated fluorodeboronation. Binding assays using arginase-expressing PC3 and LNCaP cells were performed. Autoradiography of lung sections from a guinea pig model of asthma overexpressing arginase and dynamic small-animal PET imaging with PC3-xenografted mice evaluated the radiotracers' specific binding and pharmacokinetics. Results:18F-fluorinated compounds were obtained with radiochemical yields of up to 5% (decay-corrected) and an average molar activity of 53 GBq⋅μmol-1 Cell and lung section experiments indicated specific binding that was blocked up to 75% after pretreatment with arginase inhibitors. Small-animal PET studies indicated fast clearance of the radiotracers (7.3 ± 0.6 min), arginase-mediated uptake, and a selective tumor accumulation (SUV, 3.0 ± 0.7). Conclusion: The new 18F-fluorinated arginase inhibitors have the potential to map increased arginase expression related to inflammatory and tumorigenic processes. 18F-FBMARS showed the highest arginase-mediated uptake in PET imaging and a significant difference between uptake in control and arginase-inhibited PC3 xenografted mice. These results encourage further research to examine the suitability of 18F-FBMARS for selecting patients for treatments with arginase inhibitors

Facile Synthesis of N-Substituted Benzimidazoles

A particularly mild and efficient one-pot synthesis of N-substituted benzimidazole derivatives was developed. 2-Fluoro-5-nitrophenylisocyanide reacts with a diverse set of primary amines to afford the respective products in moderate to very good yield (35-95%; 20 examples)

Fuzzy Logic Modeling of Heat Transfer in a double Pipe Heat Exchanger with Wavy (Corrugated) Twisted Tape Inserts

Fuzzy logic is a method which can be used to model the experiments, and it has been introduced for the first time in 1965 by Zadeh . T he present work represents the use of fuzzy logic to model and predict the experimental results of heat transfer in a double Pipe Heat Exchanger with Wavy (Corrugated) Twiste d Tape Inserts . The tape consists of the corrugations and the twisting with various twist ratios (TR=10.7, 8.5, 7.1) . The length, width and thickness of twisted tape were 1 m, 14 mm and 2 mm respectively. The Reynolds number is varied from 5000 to 17 000

Fuzzy Logic Modeling of Heat Transfer in A Double Pipe Heat Exchanger with Wavy (Corrugated) Twisted Tape Inserts

Fuzzy logic is a method which can be used to model the experiments, and it has been introduced for the first time in 1965 by Zadeh . T he present work represents the use of fuzzy logic to model and predict the experimental results of heat transfer in a double Pipe Heat Exchanger with Wavy (Corrugated) Twiste d Tape Inserts . The tape consists of the corrugations and the twisting with various twist ratios (TR=10.7, 8.5, 7.1) . The length, width and thickness of twisted tape were 1 m, 14 mm and 2 mm respectively. The Reynolds number is varied from 5000 to 17 000