Catalytic activity of supported solid catalysts for phenol hydroxylation

Cobalt(II), copper(II) and zinc(II) complexes of 2-phenylbenzimidazole (PhBzlH) encapsulated in the supercages of zeolite-Y and ZSM-5 have been synthesized and characterized by spectroscopic studies (IR, UV/visible, EPR), elemental analyses, thermal studies and X-ray diffraction patterns. The catalytic activity of encapsulated complexes was investigated for the hydroxylation of phenol using 30 % H₂O₂ as an oxidant. Under optimized reaction conditions, the hydroxylation of phenol yielded catechol and hydroquinone as the major products. All catalysts show good selectivity for diphenol products. A maximum conversion of phenol was obtained with [Cu(PhBzlH)]-Y as the catalyst. The results showed that conversion of phenol varies in the order [Cu(PhBzlH)]-Y (53 %) > [Cu(PhBzlH)]-ZSM-5 > (49 %) > [Co(PhBzlH)]-ZSM-5 (47 %) > [Co(PhBzlH)]-Y (46 %) > [Zn(PhBzlH)]-Y (45 %) > [Zn(PhBzlH)]-ZSM-5 (41 %) after 6 h of reaction time. Test for the recyclability of the reaction was also carried out and the results indicate their recyclability.     

Structural,thermal, dielectric,nonlinear optical properties and DFT investigations of a novel material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide for optoelectronic applications

A new organic nonlinear optical (NLO) material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide (CDA) has been synthesized by reflux method. Single crystals were grown by slow evaporation technique and the crystal structure was elucidated by single crystal X-ray diffraction method. Density functional theory (DFT) calculations at B3LYP/6–31+?+?G(d, p) basis set was used to predict the molecular geometry and were carried out further to comprehend the electronic structure, vibrational spectra, natural bonding orbitals (NBO), frontier molecular orbitals (FMO) and molecular electrostatic potential (MEP). An optical transparency at the cut-off wavelength of 355 nm was determined by UV–Vis–NIR spectroscopy. Thermal behavior of CDA was studied by TGA/DTA analysis. The dielectric constant (ε), dielectric loss (tan δ) and AC conductivity as a function of frequency and temperature was studied. Second Harmonic Generation (SHG) efficiency of the CDA was determined using Kurtz and Perry powder technique and was 0.5 times greater than that of the KDP crystal. The third-order nonlinear optical properties were investigated in solution by Z-scan technique using a continuous wave (CW) DPSS laser at the wavelength of 532 nm. The title compound exhibited significant two-photon absorption (β?=?2.228?×?10–4 cm W^?1), nonlinear refraction (n₂?=?1.095?×?10–8 cm² W^?1) and optical limiting (OL threshold?=?2.511?×?103 W cm^?2) under the CW regime. The nonlinear optical parameters were calculated using time-dependent Hartree–Fock (TDHF) method. The overall obtained results suggested that the studied CDA molecule could be a potential NLO material for frequency generator, optical limiters and optical switching applications.

     

Bulk production of porous TiO2 nanowires by unique solvo-plasma oxidation approach for combating biotic and abiotic water contaminants

Pure, porous titania nanowires (TiO₂-pNW) are produced in bulk amount (~?250 kg/day, reaction time scale?<?1 min) using a unique solvo-plasma oxidation method utilizing microwave plasma with the potential of easy scale up. The prepared nanowire is found to be efficient towards both biotic disinfection and destruction of various abiotic contaminants in wastewaters. In terms of organic contaminants, the TiO₂-pNW is tested for destruction of Rhodamine B (RhB) dye, tetracycline (TC) antibiotic, and diclofenac (DFC) and caffeine (CAF) drugs. In the case of biotic contaminants, the disinfection of E. coli bacteria is demonstrated. In all of the studies, the photocatalytic performance of anatase TiO₂-pNW is compared to that of commercially available P25 nanoparticles (TiO₂-P25), both in the presence and absence of ozone. The excellent photoactivity exhibited by TiO₂-pNW is a result of low recombination rate of electron–hole pair owing to the spatial separation of electrons and holes within the photoexcited nanowires. Moreover, the scavenger experiments and experiments involving ozone reveal that electron transfer and/or presence of dissolved oxygen are the major limiting factors for both porous titania nanowires and P25 spherical powder under UV exposure with photocatalytic activity towards pollutant degradation.

     

Classical and Bayesian inference of Cpy for generalized Lindley distributed quality characteristic

The process capability index (PCI) is a quality control–related statistic mostly used in the manufacturing industry, which is used to assess the capability of some monitored process. It is of great significance to quality control engineers as it quantifies the relation between the actual performance of the process and the preset specifications of the product. Most of the traditional PCIs performed well when process follows the normal behaviour. However, using these traditional indices to evaluate a non‐normally distributed process often leads to inaccurate results. In this article, we consider a new PCI, C_py, suggested by Maiti et al, which can be used for normal as well as non‐normal random variables. This article addresses the different methods of estimation of the PCI C_py from both frequentist and Bayesian view points of generalized Lindley distribution suggested by Nadarajah et al. We briefly describe different frequentist approaches, namely, maximum likelihood estimators, least square and weighted least square estimators, and maximum product of spacings estimators. Next, we consider Bayes estimation under squared error loss function using gamma priors for both shape and scale parameters for the considered model. We use Tierney and Kadane's method as well as Markov Chain Monte Carlo procedure to compute approximate Bayes estimates. Besides, two parametric bootstrap confidence intervals using frequentist approaches are provided to compare with highest posterior density credible intervals. Furthermore, Monte Carlo simulation study has been carried out to compare the performances of the classical and the Bayes estimates of C_py in terms of mean squared errors along with the average width and coverage probabilities. Finally, two real data sets have been analysed for illustrative purposes.     

Nanostructured and Nonsymmetrical NiO–SDC/SDC Composite Anode Performance via a Microwave-Assisted Route for Intermediate-Temperature Solid Oxide Fuel Cells

This work investigates the electrical properties of NiO–SDC/SDC anode sintered at approximately 1200°C for 1 h via the microwave method. Nanopowders Sm_0.2Ce_0.8O_1.9 (SDC—samaria-doped ceria) and NiO were mixed using a high-energy ball mill and subsequently co-pressed at three different compaction pressures of 200, 300, and 400 MPa. This study determines the effect of compaction pressure on the electrochemical performance of Ni–SDC/SDC anode, with no binder used between layers. The electrical behavior of the prepared anode was studied via electrochemical impedance spectroscopy in controlled atmospheres, operating at high temperatures (600–800°C). The results indicate that decreasing the compaction pressure and increasing the operating temperature lead to a high electrochemical performance of the nonsymmetrical NiO–SDC/SDC anode. The mechanism for manufacturing NiO–SDC/SDC involves ball milling, dry pressing, and microwave furnace sintering processes.     

Biogenically engineered nanoparticles inhibit Fusarium oxysporum causing soft‐rot of ginger

Soft‐rot of ginger (Zingiber officinale) is the most important disease usually caused by Fusarium oxysporum (F. oxysporum) leading to significant yield loss. In this study, chitosan, copper and sulphur nanoparticles synthesised from leaf extract of selected plants were screened against two isolates of F. oxysporum recovered from the infected rhizome of ginger and soil samples. Moreover, among these, sulphur nanoparticles showed maximum inhibition of F. oxysporum isolated from soil samples (ZOI = 12.33 mm) followed by copper (ZOI = >12 mm) and chitosan nanoparticles (ZOI = >9 mm). Similarly, in the case of F. oxysporum isolated from infected ginger, sulphur nanoparticles showed maximum inhibition (ZOI = 13.33) as compared to copper (ZOI = >11 mm) and chitosan nanoparticles (ZOI = >9 mm). Considering the high efficacy, sulphur nanoparticles were further evaluated in combination with commercial fungicides, viz., bavistin, ridomil gold, sunflex and streptocycline. The combination of sulphur nanoparticles with bavistin demonstrated maximum inhibition (ZOI = 45.16 mm, MIC −20 µg/ml), whereas the minimum inhibition was shown by its combination with ridomil gold (ZOI = 10.5 mm, MIC –40 µg/ml). Therefore, it can be concluded that the combination of sulphur nanoparticles with bavistin can be used for effective and eco‐friendly management of F. oxysporum causing soft‐rot of ginger.Inspec keywords: nanoparticles, biotechnology, microorganisms, toxicology, mass spectroscopic chemical analysis, antibacterial activity, plant diseasesOther keywords: fusarium oxysporum, sulphur nanoparticles, f. oxysporum, soil samples, bavistin demonstrated maximum inhibition, biogenically engineered nanoparticles, ginger soft‐rot, chitosan nanoparticles, ridomil gold     

Fischer–Tropsch synthesis with Co/SiO2–Al2O3 catalyst and steady-state modeling using artificial neural networks

This paper reports the results of an experimental study involving Fischer–Tropsch synthesis on Co/SiO₂–Al₂O₃ catalyst. The objective of the study was to find the reaction conditions for achieving an optimal selectivity with respect to -liquid hydrocarbons. The experimental data on reaction conversion and steady-state concentrations of different product species has been used to develop artificial neural-network-based models which are generic and can be used for predicting the reaction behaviour under different operating conditions.     

Recent Approaches to Antifungal Therapy for Invasive Mycoses

Antimycotic agents : Diverse classes of antimycotic drugs have been developed over the past decades with the goal of improving selectivity and efficacy. This review discusses both conventional and novel targets for antifungal agents and the possibility of vaccination in the treatment of invasive fungal infections.

     

Evolving nanotechnological trends in the management of mycotic keratitis

The alarming increase in global burden of various corneal diseases in general and mycotic keratitis in particular has raised up a major concern for its treatment. Mycotic keratitis is one of the most serious infections among the various ocular diseases. The proper diagnosis and effective treatment strategies remain a great challenge for ophthalmologists. The inefficacy and failure of conventional treatments have generated need to develop alternative approaches for the treatment of mycotic keratitis. Considering the promising applications of nanotechnology in biomedical area, it is believed that various nanomaterials can be effectively used in the management of mycotic keratitis. This review focuses on worldwide burden of various corneal diseases including mycotic keratitis and the role of nanotechnology in its treatment. In addition, safety and toxicological issues are also discussed.Inspec keywords: toxicology, reviews, eye, patient diagnosis, diseases, patient treatment, nanomedicineOther keywords: mycotic keratitis, corneal diseases, nanotechnology, ocular diseases     

Prevention of Damage to Cuffed Catheters

Cuffed catheters, although not ideal for long-term use, are now used more frequently due to an increase in the aging population, in whom the vessels are not suitable for either arteriovenous fistulas or polytetrafluoroethylene (PTFE) grafts. Infections and thrombosis remain the major causes for removal or change of catheters. We recently identified eight catheter defects that required replacement of catheters. Of these, two were due to patient negligence: one catheter was accidentally severed while the patient was shaving; the other was snipped during a haircut. One was believed to have a manufacturing defect. One catheter sustained needle-prick damage near the hub while irrigating the catheter. Two catheters were lost due to needle pricks during skin closure, and one catheter sustained similar damage while fixing the suture wing to the skin. The other two were damaged by suture material slicing through the lumen of the catheter as it expanded due to increased blood flow during repeated dialyses. Importantly, several of these injuries to the catheters were not immediately obvious and were detected only after repeated use of the catheters. Delayed bleeding of cuffed catheters necessitating change or removal has not been reported. Such bleeding may be due to manufacturing defects, patient carelessness, or iatrogenic causes. Avoiding the use of sutures can minimize the latter. Skin closure strips and a double transparent dressing may serve the same purposes, such as securing the catheter and aiding wound healing. In addition, these dressings have the added advantage of being waterproof, bacteria-proof, and cost effective.