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The nanoscale Li2Mn0.8Ni0.2SiO4/ MnO2 composite was successfully prepared via a two-step method. Firstly, by the preparation of MnO2 nanoparticles through an oxidation-reduction reaction; secondly, by synthesizing Li2Mn0.8Ni0.2SiO4 using the EDTA-assisted...

Downy mildew of squash caused by Pseudoperonospora cubensis is considered one of the serious diseases that affect cucurbits crops in Egypt and all the world. This study was conducted to find alternative safe methods for controlling downy mildew disease. The use of plant extracts, essential oils, growth regulators and foliar fertilization with nitrogen, potassium and phosphorus showed that these treatments reduce disease incidence and lead to a significant increase in yield compared to untreated plants. Growth characteristics of squash plants i.e., plant height, leaf area, root length, shoot length, plant fresh weight and plant dry weight were significantly increased in response to the application of any tested control methods compared to the untreated control plants. Total water content (TWC), relative water content (RWC) and transpiration rate of squash plants were remarkably increased in response to the application of either Gibberellin, black cumin oil, clove oil (10%), mint oil (5%), Thuja extract and/or the fungicide in comparison with the untreated control. Application of the disease control methods to squash plants increased chlorophyll, total sugars content and proline concentration compared to the untreated control plants.

This study successfully synthesized Li2MnSiO4/Mn3O4 (LMS/M3) and Li2Mn0.8Ni0.2SiO4/Mn3O4 (LMNS/M3) nanocomposites in a two-step method first, by preparing Mn3O4 (M3) nanoparticles through a hydrothermal method and second, by synthesizing Li2MnSiO4 (LMS) and Li2Mn0.8Ni0.2SiO4 (LMNS) by ethylene diamine tetra-acetic assisted sol–gel method. In the last method, the two nanoparticles are mixed by hand-milling to form nanocomposites. Synthesized nanoparticles were characterized using X-ray diffraction, Fourier-transform infrared, Raman spectra, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller surface area, pL and UV–vis spectra measurements. The nanocomposite presents a well-developed orthorhombic crystal structure with a Pmn21 space group. BET surface area measurements indicate that all the prepared materials are mesoporous. The photocatalytic activity of M3, LMS, LMNS, (LMS/M3), and (LMNS/M3) was investigated by the photocatalytic degradation of reactive blue 5 (RB5) under UV light irradiation using a homemade photoreactor. The maximum photodegradation was achieved at optimal pH 4 and photocatalyst dose 0.005 g/50 ml dye. Higher stability for dye degradation efficiency was attained for the LMS and LMNS nanomaterials and LMS/M3 and LMNS/M3 nanocomposites than M3 to photocatalytic activity. The photocatalyst is readily recoverable and shows excellent stability even after three cycles. The photocatalytic degradation for RB5 followed first-order kinetics. Graphical Abstract