Inspection scheduling for imperfect production processes under free repair warranty contract

The paper considers scheduling of inspections for imperfect production processes where the process shift time from an ‘in-control’ state to an ‘out-of-control’ state is assumed to follow an arbitrary probability distribution with an increasing failure (hazard) rate and the products are sold with a free repair warranty (FRW) contract. During each production run, the process is monitored through inspections to assess its state. If at any inspection the process is found in ‘out-of-control’ state, then restoration is performed. The model is formulated under two different inspection policies: (i) no action is taken during a production run unless the system is discovered in an ‘out-of-control’ state by inspection and (ii) preventive repair action is undertaken once the ‘in-control’ state of the process is detected by inspection. The expected sum of pre-sale and post-sale costs per unit item is taken as a criterion of optimality. We propose a computational algorithm to determine the optimal inspection policy numerically, as it is quite hard to derive analytically. To ease the computational difficulties, we further employ an approximate method which determines a suboptimal inspection policy. A comparison between the optimal and suboptimal inspection policies is made and the impact of FRW on the optimal inspection policy is investigated in a numerical example.     

Magnetic and electrical transport properties in the self-doped manganite La0.9Mn0.9M0.1O3 (M=Mn,Zn and Ti)

The magnetic and electrical transport properties of La_0.9Mn_0.9M_0.1O₃ (M=Mn, Zn and Ti) were investigated. The temperature and magnetic field dependence of electrical resistivity (ρ) and dc magnetization were studied. All the compounds are found in rhombohedral structure. The excess oxygen in all three compounds was detected through iodometric titration. A modification in resistivity is observed when M=Mn is replaced by M=Zn and Ti. The high temperature resistivity above T_C follow variable range hopping model for both Zn and Ti compounds. For Zn doping, the observation of large field-cool effect and decrease in resistivity at room temperature and is assumed to be due to the implant of Mn⁴⁺ in Mn³⁺ matrix, which favor Mn³⁺/Mn⁴⁺ double exchange. The ferromagnetic behavior below T_C for the compound with M=Ti is correlated to the excess oxygen in it, which implants Mn⁴⁺ and thus incorporates ferromagnetic interactions. The substitutions lead to a reduction of T_c and magnetization.     

Synthesis of amino ester-embedded benzimidazoles: a one-pot sequential protocol under metal-free neutral conditions

A one-pot three-component protocol has been developed for the synthesis of amino ester-embedded benzimidazoles under metal-free neutral conditions. Sequentially, the methodology involves coupling of an amino ester with 1-fluoro-2-nitrobenzene, reduction of the coupled nitroarene by sodium dithionite, and cyclization of the corresponding diamine with an aldehyde.     

Biogenic synthesis of Fe2O3@SiO2 nanoparticles for ipso-hydroxylation of boronic acid in water

Here, biogenic synthesis of Fe₂O₃@SiO₂ nanoparticles using fruit extract of Zanthoxylum rhetsa is reported. The SiO₂ nanoparticles was synthesized using paddy straw which is a byproduct obtained in cultivation of rice. The composite was characterised by spectroscopic method like XRD, SEM, TEM and EDX analysis. The ipso-hydroxylation reactions were carried out with excellent yield within a moderate time period with mild reaction condition in all cases. Therefore, this approach may be considered as simple, easy, cheap and greener, environment friendly protocol for ipso-hydroxylation of arylboronic acids at 50 °C temperature.     

Spectroscopic and spectrometric studies of anion recognition with calix[4]pyrroles in different reaction conditions

The binding studies of calix[4]pyrroles (1–6) with fluoro, chloro, bromo, iodo and sulphato anions generated from normal-tetrabutylammoniumfluoride, normal-tetrabutylammoniumchloride, normal-tetrabutylammoniumbromide, normal-tetrabutylammoniumiodide, and normal-tetrabutylammoniumsulphate respectively were investigated by electrospray ionization mass spectrometry (ESI-MS) in dichloromethane–acetonitrile in negative ion mode. The efficacy of a particular calix[4]pyrrole to bind with anions was found maximum at low cone voltage of the instrument, at high cone voltage the binding was suppressed due to removal of anion from the cavity of the macrocycles. The binding strength was found inversely proportional to the size of anion for a particular calix[4]pyrrole. The fragmentation pattern of calix[4]pyrrole was observed at higher cone voltage of ESI-MS and was interpreted. The association constants of calix[4]pyrroles and anions obtained from electronic transition studies were in good agreement with that observed from ¹H NMR titration studies.     

Triphenylphosphine chalcogenides as efficient ligands for room temperature palladium(II)-catalyzed Suzuki-Miyaura reaction

A simple catalytic system based on PdCl₂ and triphenylphosphine chalcogenides (PPh₃X; X = O, S, Se) is found to be highly effective (up to 97% isolated yield) in the room temperature Suzuki-Miyaura reactions. Under the same experimental conditions, triphenylphosphine chalcogenides as ligands show superior activities compared to free triphenylphosphine.     

Agrobacterium-Mediated Transformation in Alpinia galanga (Linn.) Willd. for Enhanced Acetoxychavicol Acetate Production

Agrobacterium-mediated transformations ensure elevated amounts of secondary metabolite accumulation with genetic and biosynthetic stability. In the present study, Alpinia galanga rich in bioactive compounds was genetically transformed using different strains of Agrobacterium rhizogenes viz. LBA 9402, A ₄ , 532, 2364 and PRTGus. Even though a higher growth rate was obtained with the LBA 9402 strain, maximum acetoxychavicol acetate accumulation (ACA) was seen in the PRTGus transformant. PRTGus root line has shown 10.1 fold higher ACA content in comparison to the control roots. The lowest ACA production was shown by the A ₄ transformant (4.9 fold). The quantification of ACA in the transformed roots was carried out by using HPLC, which was found to be in the order of PRTGus > LBA 9402 > 2364 > 532 > A ₄ . The fast growth rate of hairy roots, genetic stability and their ability to synthesize more than one metabolite offer a promising system for the production of valuable secondary metabolites.     

Magnetism and transport studies in off-stoichiometric metallic perovskite compounds GdPd3Bx (x=0.25, 0.50 and 0.75)

We report the magnetic and transport properties of the off-stoichiometric metallic perovskite like compounds GdPd₃B_x (x=0.25, 0.50 and 0.75). Our results show that doping with boron in the lattice of parent binary-compound GdPd₃ leads to lattice expansion. Which in turn manifests in contrasting magnetic and transport behaviors of the doped compounds in comparison with the undoped GdPd₃. An attempt has been made to compare and correlate the results of magnetic and transport measurements of GdPd₃B_x with that of stoichiometric compositions GdPd₃B_xC_1−x. The comparative study of GdPd₃B_x and GdPd₃B_xC_1−x confirms that there is a strong correlations between the structural, magnetic and transport properties of these compounds.     

Selective functionalization of ferrocenyl compounds using a novel solvent free synthetic method for the preparation of bioactive unsymmetrical ferrocenyl derivatives

A novel solvent free synthetic method has been designed by using rice husk ash (RHA) as solid support for the selective functionalization of ferrocenyl derivatives and described the synthesis of a 1,1′‐unsymmetrically bi‐functionalized ferrocenyl compounds for their biological evaluation. Single crystal X‐ray structural evaluation showed some interesting intra‐molecular hydrogen bonding interactions across the chains of the ferrocenyl molecule, while DFT calculation revealed the significance of the orientation between the two cyclopentadienyl rings for the hydrogen bonding interaction. Redox and antibacterial properties have been studied to understand the electronic and biological effect of different hydrazone system and their potential for future application.