“Optimization of aircraft maintenance/support infrastructure using genetic algorithms—level of repair analysis”

Level of repair analysis (LORA) is an approach used during the design stage of complex equipment for analysis of the cost effectiveness of competing maintenance strategies. LORA is carried as a part of the life cycle cost and cost of ownership analysis and plays a significant role in minimizing the life cycle cost and cost of ownership of the capital equipment. Since many purchasing decisions of complex equipment are based on cost of ownership, it has become essential to carry out LORA to compete in the market. In this paper, we develop a mathematical model for LORA and propose a solution methodology based on genetic algorithms. The concept is illustrated using a hypothetical aircraft engine.     

A versatile and efficient synthesis of (2S)-2-(hydroxymethyl)-N-Boc-2,3-dihydro-4-pyridone

A versatile and efficient method for the preparation of (2S)-2-(hydroxymethyl)-N-Boc-2,3-dihydro-4-pyridone from l-(−)-phenylalanine 2 utilising the aromatic system as a masked β-keto aldehyde was developed. The key step in the sequence is an intramolecular cyclisation of 6 to give 2,3-dihydropyridin-4-ones.     

A novel synthesis of amino acid derivatives of phospholene oxides

A convenient synthetic approach is established to prepare a new class of 1-l-α-amino acid derivatives of phospholene oxides by amination of (±)-1-chloro-2-phospholene-1-oxides with several optically pure l-α-amino acid esters. All compounds obtained as a diastereomeric mixture in good to high yields. The two diastereomers were successfully separated by column chromatography and structurally identified by their spectral analyses.     

Targeting non-structural proteins and 3CLpro in SARS-CoV-2 virus using phytochemicals from medicinal plants - In-silico approach

In the present study, the main protease 3CL^pro and non-structural protein (NSP-12 with co-factors 7 and 8) trimer complex are used to study the protein-drug interactions with the phytochemicals from Ocimum Sanctum, Tinospora Cordifolia, Glycyrrhiza Glabra, and Azadirachta Indica. Which can give insight to be used as potent antiviral drugs against SARS-CoV-2. Twenty phytochemicals, five from each plant species, known for their wide range of biological activities were chosen from the literature. The in-silico study was carried out using virtual screening tools and the top five, which showed the least binding energies, were selected. Molecular docking tools revealed that gedunin and epoxy azadiradione proved to be excellent inhibitors for 3CL^pro and so did Tinosporide for non-structural-protein complex. Further, the best-hit phytochemicals with respect to structure similarities with FDA drugs and investigatory drugs, were considered for comparative study. Molecular docking was done to check the drug-protein interactions and to check the inhibitory responses of these drugs against the viral protein. The analyses showed that the phytochemicals had similar responses on the protein complex but with exceptionally higher inhibitory responses hence which may be taken for further clinical study.     

Zinc deposition during ESI-MS analysis of peptide-zinc complexes

Electrospray ionization (ESI) mass spectrometry (MS) has proven to be an extremely powerful technique for studying the stoichiometry and binding strength of peptide-metal complexes. We have found a significant new problem in the ESI-MS of zinc-peptide systems involving the deposition of zinc in the ESI emitter. This deposition of zinc during the experiment removes a significant amount of zinc ions from the solution, impacting the resulting mass spectral intensities used to quantify the amount of the zinc-bound species. Analysis of infused zinc-peptide samples with atomic absorption spectrometry and with a custom-built nanoflow ESI source confirms the alteration of the analyte solutions with positive or negative or no potential applied to the emitter. Ultimately, the location of the zinc deposition was determined to be the stainless steel emitter. The use of a custom-built nanoESI interface using glass emitters was found to mitigate the zinc deposition problem. The phenomenon of metal deposition warrants further investigation as it may not be limited to just zinc and may represent a significant obstacle in the ESI-MS analysis of all protein-metal systems.     

The Indian auto component industry – Estimation of operational efficiency and its determinants using DEA

In this paper, the performance analysis of the Indian auto component industry is carried out from the perspectives of an original equipment manufacturer and a component supplier. Various efficiency measures are estimated using Data Envelopment Analysis with publicly available financial data on a representative sample of 50 firms. The first stage analysis reveals various operational inefficiencies in the auto component industry which are subsequently decomposed into technical, input mix and scale efficiencies. The study finds evidence that a majority of the inefficient firms are operating in the diminishing returns to scale region and demonstrates potential savings through benchmark input targets. A second stage analysis aimed at exploring root causes of inefficiencies finds that substitution of labour for capital could be causing a variety of inefficiencies including the input mix inefficiency in the Indian component industry. The empirical results also suggest that, unlike the global auto supply chain, higher average inventories are required for higher operational efficiencies in the Indian context. Contrary to the popular expectations, the technology licensing does not show significant influence on efficiency, at least in the short term, whereas efficient working capital management does result in higher operational efficiencies. The study also unearths the need to reform labour laws which are significantly contributing to various inefficiencies in the Indian component industry.     

Optical and luminescence properties of Dy3+ ions in K–Sr–Al phosphate glasses for yellow laser applications

Trivalent dysprosium (Dy³⁺)-doped K–Sr–Al phosphate glasses have been prepared and investigated for their optical and luminescence properties. Judd–Ofelt theory has been used to derive radiative properties for the ⁴F_9/2 level of Dy³⁺ ions. The luminescence spectrum of 1.0 mol% Dy₂O₃-doped glass shows intense yellow emission around 572 nm ascribed to ⁴F_9/2 → ⁶H_13/2 transition with 78 % branching ratio and emission cross section of the order of 2.48 × 10^?21 cm². Moreover, the quantum efficiency of the ⁴F_9/2 level has been found to be 76 %. The luminescence decay curves for the yellow emission (⁴F_9/2 → ⁶H_13/2) have been measured and analyzed as a function of Dy³⁺ ion concentration. The results revealed that Dy³⁺-doped phosphate glasses could be useful for yellow laser applications.     

Catalysis by Amberlyst A-21: A Greener Approach to 4,5,6,7-Tetrahydro-1H-indazol-3(2H)-ones via Construction of Cyclohexanones

The 4,5,6,7-tetrahydro-1H-indazol-3(2H)-one derivatives have been synthesized in good yields via a two-step method in a single pot. The initial step involved the construction of cyclohexanone ring from aromatic aldehydes and β-ketoester in i-PrOH using an inexpensive and reusable catalyst (i.e., Amberlyst A-21) under mild reaction conditions. The utility of this catalyst has been demonstrated in synthesizing a range of cyclohexanone derivatives. The catalyst can be recovered and recycled, which makes this procedure simple, convenient, economically viable, and environmental friendly.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Purification and Characterization of an Antifungal Chitinase from Citrobacter freundii str. nov. haritD11

The purpose of the research was to study the purification and partial characterization of antifungal alkaline chitinase from a newly isolated Citrobacter freundii haritD11. The enzyme was purified in a three-step procedure involving ammonium sulfate precipitation, dialysis, and Sephadex G-100 gel filtration chromatography. The enzyme was shown to have a relative high molecular weight of 64 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis and was purified 7.3-fold with a yield of 18.8 %. It was most active at 35 °C, pH 8.0, with colloid chitin as substrate and was very stable at alkaline pH contradicting the characteristic that most of the bacterial chitinases are active at acidic pH. Further, the purified chitinase exhibited remarkable antifungal activity against pathogenic fungi Aspergillus flavus MTCC 2798 and Aspergillus niger MTCC 9652 showing diametric inhibition zones of 27 mm and 21 mm, respectively.     

Room temperature-stable electride as a synthetic organic reagent: application to pinacol coupling reaction in aqueous media

Room temperature-stable inorganic electride [Ca(24)Al(28)O(68)](4+)4e(-) was employed for a pinacol coupling reaction in aqueous media. Ca-Al-O gel formed by the destruction of the crystal structure of an electride by water media played a key role in transferring the electron to electrophilic aldehydes. Aromatic aldehydes reacted smoothly with moderate to high yields.