Cobalt-Substituted Heteropolyanion: Synthesis, Characterization, and Application to Oxidation of an Organic Dye in an Aqueous Medium

Conservation Environments' Effect on the Compressive Strength Behaviour of Wood-Concrete Composites

This paper addresses the issues in making wood-concrete composites more resilient to environmental conditions and to improve their compressive strength. Tests were carried out on cubic specimens of 10 × 10 × 10 cm³ composed of ordinary concrete with a 2% redwood- and hardwood-chip dosage. Superficial treatments of cement and lime were applied to the wood chips. All specimens were kept for 28 days in the open air and for 12 months in: the open air, drinking water, seawater, and an oven. Consequently, the compressive strength of ordinary concrete is approximately 37.1 MPa. After 365 days of exposure to the open air, drinking water, seawater, and the oven, a resistance loss of 35.84, 36.06, 42.85, and 52.30% were observed, respectively. In all environments investigated, the untreated wood composite concrete's resistance decreased significantly, while the cement/lime treatment of the wood enhanced them. However, only 15.5 MPa and 14.6 MPa were attained after the first 28 days in the cases of the redwood and the hardwood treated with lime. These findings indicate that the resistance of wood-concrete composites depends on the type of wood used. Treating wood chips with cement is a potential method for making these materials resistant in conservation situations determined by the cement's chemical composition. The current study has implications for researchers and practitioners for further understanding the impact of these eco-friendly concretes in the construction industry.

Tungsten-substituted molybdophosphoric acid impregnated with kaolin: effective catalysts for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones via biginelli reaction

A series of highly reusable heterogeneous catalysts (10-25 wt% PMo7W5/kaolin), consisting of tungsten-substituted molybdophosphoric acid, H3PMo7W5O40·24H2O (PMo7W5) impregnated with acid treated kaolin clay was synthesized by the wetness impregnation method. The newly synthesized catalyst was fully characterized using inductively coupled plasma-atomic emission spectroscopy (ICP-AES), Fourier transform infrared (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis and thermal analysis (TG-DTA). The synthesized materials were shown to be efficient in the synthesis of 3,4-dihydropyrimidin-2(1H)-ones via Biginelli reaction under solvent-free conditions. The obtained results indicate that 20% PMo7W5/kaolin catalyst showed remarkably enhanced catalytic activity compared to the bulk PMo7W5 catalyst, and also the (10 and 15%) PMo7W5 catalyst supported on kaolin clay.

Review of a controversial treatment method in the fight against COVID-19 with the example of Algeria

BACKGROUND

As of April 23, 2021, more than 145 million cases and almost 3.07 million related deaths were noted because of the coronavirus (Covid-19) Pandemic. Considering the low rate vaccination, the alternative that divided opinions for a long time is an old medicine called hydroxychloroquine.

MAIN BODY

The aim of this review was to synthesize the different highlights of the most important studies published since the beginning of the epidemic crisis. After a precise study of the available bibliography dealing with this subject and the addition of an adapted example, which is the current situation of Algeria, the results showed the effectiveness of the Algerian method as well as the impact that this treatment had.

CONCLUSION

We concluded that in brief, given the inexistence of a better solution, we ultimately recommend that patients with severe COVID-19 to be treated for the moment with Hydroxychloroquine combined with Azithromycin in view of its effectiveness, while waiting for another solution.