This study investigated how the water–cement ratio and silica fume concentration affect the compressive strength of cement mortars. This comprehensive study delved into the intricate interplay between water–cement ratio and silica fume concentration, examining their influence on cement-based mortars’ compressive strength and water absorption characteristics. The silica fume concentration was investigated, ranging from 5% to 15% of the cement weight. The investigation employed two distinct mixing techniques, mixing cement and silica fume, before extracting appropriate samples; alternatively, a magnetic stirrer was used to prepare samples by dissolving silica fume in water. The cement mortars were also prepared with three different water–cement ratios: 0.44, 0.47, and 0.5. The interesting findings of compressive tests illuminated a consistent trend across all curing days and mixing methods—a reduction in the water–cement ratio corresponded with a notable increase in compressive strength. However, it is essential to note that the influence of the mixing method on the compressive strength of cement-based mortars is based on the water–cement ratio. The results show that by using the suggested technological method, it was observed that samples prepared with water–cement ratios (W/C) of 0.47 and 0.44 exhibited higher compressive strengths compared to those prepared using the well-known standard mixing method. The compressive test results underscored that the water–cement ratio reduction consistently enhanced the compressive strength in every combination of curing days and mixing techniques. Furthermore, this reduction in the water–cement ratio was correlated with a decrease in water absorption of the mortar. Conversely, the water–cement ratio itself played a pivotal role in defining how the mixing technique affected the compressive strength and water absorption of cement-based mortars. This multifaceted exploration underscores the nuanced relationships between key variables, emphasizing the need for a comprehensive understanding of the intricate factors influencing the mechanical and absorptive properties of cement-based materials.

On the basis of 2-benzyl-6-hydroxypyridazin-3(2 H)-one, a series of its novel O-substituted (including 6-(1,3,5-triazin-2-yl)oxy) derivatives is prepared. It is proven that the substitution reactions in the initial compound occur mainly at the oxygen atom of the hydroxy group. On the basis of the obtained oxy-aceto(propane)hydrazides, the corresponding azides and anilides are synthesized. A series of 2-[(1-benzyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy]- N′-(substituted benzylidene)aceto(propane)hydrazides is obtained via the reaction of various aromatic aldehydes with the same hydrazides. Heterocyclization of the latter affords compounds with a combination of pyridazine and 1,3,4-oxadiazole rings in the molecule. The reaction of oxy-acetohydrazide with potassium thiocyanate and a mixture of CS₂/KOH leads to potassium salts of 2-{[(1-benzyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy]methyl}hydrazine-1-carbothioamide and 2-{2-[(1-benzyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy]acetyl}hydrazine-1-carbodithioic acid, respectively. Acid hydrolysis of the latter affords 2-benzyl-6-[(5-thioxo-4,5-dihydro-1,3,4-thiadiazol-2-yl)methoxy]pyridazin-3(2 H)-one.

A new series of pyrazolylpyridazine derivatives was obtained on the basis of 3-pyrazol-1-yl-6-hydrazinylpyridazine. Biological screening has identified a number of compounds that have a stimulating effect on plant growth.

This study examines the influence of pyrolysis temperature on the physicochemical characteristics of malt-derived biochar (BC) and its effect on the performance of cement mortars. Malt biomass, a by-product of the brewing industry, was subjected to pyrolysis at 300 °C and 500 °C, followed by high-energy ball milling to produce nanoscale biochar. Characterization using FTIR, Raman spectroscopy, XRD, BET, SEM, and XRF revealed that BC500 possessed higher graphitic ordering, larger specific surface area (110 m₂/g), and smaller pore size compared to BC300, which exhibited greater hydrophobicity. Incorporation of BC500 into cement mortars at 0.25–1.0 wt.%, with and without superplasticizer, resulted in up to a 20.6% increase in compressive strength and a significant reduction in water absorption. These enhancements are attributed to the internal curing effect of biochar, its refined pore structure, and improved interfacial bonding with hydration products. The findings demonstrate that optimized malt biochar serves as a sustainable additive that improves the mechanical performance and durability of cementitious materials while advancing circular economy principles through the valorization of industrial malt waste and the mitigation of the environmental impact of cement production.

A convenient, accessible, and high yield method for preparing of 6-methyl-2-thioxo-2,3-dihydropyrimidin-4(1H)-one (1) by treatment of acetoacetic acid ethyl ester with thiourea in sodium methylate was developed. The alkylation of the latter with 3-chloro-pentane-2,4-dione and further regioselective cyclization of intermediate compound (2) in high yield afforded 2-acetyl-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidin-5-one (3). The halogenation and some transformations of synthesized thiazolo[3,2-a]pyrimidine (3) due to its ketone group were carried out to obtain the corresponding carboxamide, carbothioamide, sulfonohydrazide, and oxime and its alkylated derivatives (5). At preliminary biological studies the synthesized compounds have shown growth stimulant properties. The activity of four of them was higher than 70%, compared with heteroauxin.

The affordable and efficient methods for the syntheses of acyclic derivatives of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)-6-oxopyridazin-1(6H)-yl)acetohydrazine as well as compounds with a combination of pyrazolyl-pyridazine fragment with various azoles in the molecules have been developed. The synthesized compounds showed a stimulating action on plant growth.