Agro-waste sourced catalyst as an eco-friendly and sustainable approach for Knoevenagel condensation reaction

Background: The present work describes an eco-friendly and sustainable approach for the Knoevenagel condensation of an aromatic aldehyde with ethyl cyanoacetate, and salicylaldehyde with Meldrum acid for the synthesis of ethyl benzylidenecyanoacetate and 3-carboxy coumarin (2-oxo-2H-1-benzopyran) derivatives, respectively. The reaction performed under greener catalytic media Water Extract of Watermelon Fruit Peel Ash (WEWFPA) is an eco-friendly protocol derived from the agro-waste feedstock. Various protocols have been reported for the synthesis of Knoevenagel condensation reaction using a hazardous catalyst or/and solvent found toxic to the environment, reaction time longer, poor yield, and required purification of the final product. The present method provides several added advantages of being completely greener, economic, giving high yield, inexpensive catalyst, and the final product isolated in pure form with good yield. Objective: The objective of the study was to develop a green methodology for the synthesis of ethyl benzylidenecyanoacetate and 3-carboxy coumarin derivatives. Results: The agro-waste based catalyst developed avoids the use of external inorganic/organic base, additives, and solvent-free synthesis of Knoevenagel condensation of ethyl benzylidenecyanoacetate and 3-carboxy coumarin derivatives under rt and microwave irradiation, respectively described. The microwave irradiation condition requires less time for the completion of the reaction and also gave better yield isolation Methods: We have demonstrated WEWFPA as a greener homogenous agro-waste is employed under rt stirring and microwave irradiation for the economic synthesis of ethyl benzylidenecyanoacetate and 3-carboxy coumarin derivatives. The developed method was found robust, non-hazardous and solvent-free with simple work-up gave target product. Conclusion: In conclusion, we have established an efficient, simple, agro-waste based catalytic approach for the synthesis of ethylbenzylidenecyanoacetate and 3-carboxy coumarin derivatives employing WEWFPA as an efficient catalyst under rt stirring and microwave synthesis, respectively. The method is a greener, economical and eco-friendly approach for the synthesis of Knoevenagel condensation products. The advantages of the present approach are solvent-free, no external metal, chemical base free, short reaction time and isolated product in good to excellent yields. The catalyst is agro-waste derived, which has abundant in natural sources, thus making the present approach a greener one.

Ultrasound-assisted synthesis of β-enaminone derivatives via Tin(Ⅳ)-catalyzed addition reaction from β-dicarbonyl compounds with nitriles

An efficient and eco-friendly approach for the synthesis of β-enaminone derivatives is described, which is through the addition of nitriles with β-dicarbonyl compounds under ultrasound irradiation condition at room temperature. The scope and limitation of this strategy are also discussed. A variety of substituted amides can be obtained in moderate to good yields. We hope that this protocol for the efficient synthesis of β-enaminones will offer insights in further investigations.

Antifungal Effect of Antimicrobial Photodynamic Therapy Mediated by Haematoporphyrin Monomethyl Ether and Aloe Emodin on Malassezia furfur

Infectious dermatological diseases caused by Malassezia furfur are often chronic, recurrent, and recalcitrant. Current therapeutic options are usually tedious, repetitive, and associated with adverse effects. Alternatives that broaden the treatment options and reduce side effects for patients are needed. Antimicrobial photodynamic therapy (aPDT) is an emerging approach that is quite suitable for superficial infections. The aim of this study is to investigate the antimicrobial efficacy and effect of aPDT mediated by haematoporphyrin monomethyl ether (HMME) and aloe emodin (AE) on clinical isolates of M. furfur in vitro. The photodynamic antimicrobial efficacy of HMME and AE against M. furfur was assessed by colony forming unit (CFU) assay. The uptake of HMME and AE by M. furfur cells was investigated by fluorescence microscopy. Reactive oxygen species (ROS) probe and flow cytometry were employed to evaluate the intracellular ROS level. The effect of HMME and AE-mediated aPDT on secreted protease and lipase activity of M. furfur was also investigated. The results showed that HMME and AE in the presence of light effectively inactivated M. furfur cells in a photosensitizer (PS) concentration and light energy dose-dependent manner. AE exhibited higher antimicrobial efficacy against M. furfur than HMME under the same irradiation condition. HMME and AE-mediated aPDT disturbed the fungal cell envelop, significantly increased the intracellular ROS level, and effectively inhibited the activity of secreted protease and lipase of M. furfur cells. The results suggest that HMME and AE have potential to serve as PSs in the photodynamic treatment of dermatological diseases caused by M. furfur, but further ex vivo or in vivo experiments are needed to verify that they can meet the requirements for clinical practice.

Effects of Gamma and Electron Beam Irradiation on FBG and DFB-FL

This paper reports the comparative experimental study concerning the irradiation effects of gamma-ray and electron beam on fiber Bragg grating (FBG) and distributed feedback fiber laser (DFB-FL). The obvious reflection wavelength shifts are observed for FBGs and DFB-FLs without evident changes in reflectivity and bandwidth under the current experimental irradiation condition, up to 60 kGy gamma radiation and 100 kGy electron beam radiation, respectively. Especially for DFB-FLs, evident attenuation in output power is observed and the rising tendency of the attenuation under increasing irradiation dose is demonstrated as well. Thus, the DFB-FLs are more suitable for radiation detection as compared to passive FBGs.

Surface characterization of laser-induced molten area in micro-grooving of silicon by ultraviolet (UV) laser

The objective of this research is to understand the fundamental mechanisms that govern the formation of laser-induced molten area during the micro-grooved fabrication on silicon material. In this research work, micro grooves were fabricated on silicon wafer by using ultraviolet (UV) laser of 248nm wavelength. Influence of lasing parameters such as pulse duration, laser pulse energy and scanning speed on the surface of micro-grooved was characterized. It is found that, the width of the micro grooves become wider with increasing laser pulse energy when ultraviolet laser was irradiated on silicon material. On the other hand, heat affected zone (HAZ) can be found at the surface of micro groove line at high pulse energy, high pulse repetition rate and lower scanning speed irradiation condition. This is considered due to the excessive heat input of the laser irradiation condition. It is concluded that proper selection of laser processing parameters of pulse energy, E, pulse repetition rate, R p , and scanning speed is necessary to achieve high quality micro-grooves.

Gold nanoparticles associated with temozolomide for glioblastoma Multiforme Treatment

Malignant neoplasms represents a group of diseases that features, as a characteristic, the genetic differentiation of the original tissue, leading to the disordered growth of cells, invading normal tissues and organs. Among the most aggressive tumors, Glioblastoma Multiforme has a mortality rate around 95% and survival’s average of 15 months, even though all treatment available. Temozolomide (TMZ) is the chemotherapeutic drug so far tested and approved with the highest response in this tumor sub-type and must be associated to other treatments to achieve better results. Thus, the purpose of this work was to evaluate the performance of this therapeutic modality with gold nanoparticles (AuNPs) and also combined with radiotherapy. TMZ hydrolysis was characterized at different pH and the chemical changes on molecular structure was determined via Fourier Transform Infrared Spectroscopy (FT-IR). The treatment performance was verified in vitro test using TMZ, TMZ plus AuNPs and associated with radiotherapy. The TMZ concentrations were varied from 0 (control group) to 1000µM, combined with AuNPs from 0 (control group) to10¹⁰ nanoparticles per well. The results showed the drug is stable at pH values between 2 to 4, but for pH values close to the physiological or basic medium, degradation is accentuated reaching a rate of 16 %/hour. The changes on molecular structure of TMZ can be observed through the FT-IR spectra, where the release of oxygen in the structure has influence on C=O group. The results of in vitro experiments showed that the highest poor results in the absence of ionizing irradiation. However, for experiments with TMZ and nanoparticles associated to radiotherapy, the performance of the treatment increased. In summary, the AuNPs showed important results under irradiation, revealing the same level of cytotoxicity for the highest TMZ concentration without irradiation. Also, the synergic effect between AuNPs and TMZ was observed under irradiation condition.

Hydrazine Radiolysis by Gamma-Ray in the N2H4–Cu+–HNO3 System

Radiolysis of chemical agents occurs during the decontamination of nuclear power plants. The γ-ray irradiation tests of the N2H4–Cu+–HNO3 solution, a decontamination agent, were performed to investigate the effect of Cu+ ion and HNO3 on N2H4 decomposition using a Co-60 high-dose irradiator. After the irradiation, the residues of N2H4 decomposition were analyzed by Ultraviolet-visible (UV) spectroscopy. NH4+ ions generated from N2H4 radiolysis were analyzed by ion chromatography. Based on the results, the decomposition mechanism of N2H4 in the N2H4–Cu+–HNO3 solution under γ-ray irradiation condition was derived. Cu+ ions form Cu+N2H4 complexes with N2H4, and then N2H4 is decomposed into intermediates. H+ ions and H● radicals generated from the reaction between H+ ion and eaq− increased the N2H4 decomposition reaction. NO3− ions promoted the N2H4 decomposition by providing additional reaction paths: (1) the reaction between NO3− ions and N2H4●+, and (2) the reaction between NO● radical, which is the radiolysis product of NO3− ion, and N2H5+. Finally, the radiolytic decomposition mechanism of N2H4 obtained in the N2H4–Cu+–HNO3 was schematically suggested.