3-[2-(5H-Indolo[2,3-b]quinoxalin-5-yl)eth­yl]-1,3-oxazolidin-2-one

The title compound, C19H16N4O2, has an almost planar fused N-heterocyclic system (r.m.s. deviation = 0.031 Å) and an almost planar five-membered 1,3-oxazolidine ring (r.m.s. deviation = 0.015 Å) at the ends of an ethyl­ene chain [N—C—C—N torsion angle = −65.6 (2)°]. The ring systems are inclined at 38.1 (1)° to one another

N′-(1-Allyl-2-oxoindolin-3-yl­idene)benzohydrazide

In the title compound, C18H15N3O2, the dihedral angle between the ring systems is 15.1 (1)°. The amino H atom is hydrogen bonded to the exocyclic O atom of the five-membered ring, forming an S(6) motif

5-(Pyridin-4-ylmeth­yl)-1H-pyrazolo­[3,4-d]pyrimidin-4(5H)-one

In the title compound, C11H9N5O, the pyrazolo­pyrimidin-4-one ring system is almost planar, with a maximum deviation of 0.0546 (13) Å for the O atom. The crystal packing is stabilized by inter­molecular N—H⋯N, C—H⋯O and C—H⋯N hydrogen bonds. In addition, π–π stacking is found between the pyridine ring and the pyrazolo­pyrimidin-4-one ring systems, with centroid–centroid distances in the range 3.9627 (12)–4.6781 (12) Å

5-Acetyl-3-hy­droxy-4-phenyl-4,5-dihydro-1H-1,5-benzodiazepin-2(3H)-one

In the title compound, C17H16N2O3, the seven-membered diazepine ring adopts a boat conformation with the hy­droxy-substituted C atom at the prow and fused benzene ring C atoms at the stern. The phenyl substituent occupies an equatorial position. The amino group of the ring system is a hydrogen-bond donor to the oxo O atom of an inversion-related mol­ecule, and the hy­droxy group is a hydrogen-bond donor to the acetyl O atom of another inversion-related mol­ecule. The two hydrogen bonds generate a ribbon motif parallel to [10] in the crystal structure

3-[2-(2,3-Dioxoindolin-1-yl)eth­yl]-1,3-oxazolidin-2-one

In the title compound, C13H12N2O4, the almost planar (r.m.s. deviation = 0.012 Å) dioxoindolinyl unit and the envelope-shaped oxazolidine ring (with the methyl­ene C atom bonded to the N atom as the flap) are linked by a —CH2—CH2— bridge, in which the N—C—C—N unit adopts a gauche conformation [torsion angle = 62.7 (2)°]

Effect of aggressive chemicals on durability and microstructure properties of concrete containing crushed new concrete aggregate and non-traditional supplementary cementitious …

The increasing awareness and usage of traditional supplementary cementitious materials (SCMs) in concrete have pressured the construction industry to look for alternatives to overcome the concerns over their plentiful availability in the future. This research illustrates the performance of recycled aggregate concrete prepared with the incorporation of available industrial by-products, namely rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) as alternatives for traditional SCMs. The effect of hydrochloric (HCl) acid and magnesium sulfate (MgSO 4) attack was evaluated by measuring the change in mass, compressive strength and microstructural analysis. The results revealed that the incorporation of RHA, POFA and POCP up to 30% minimizes concrete deterioration and loss in compressive strength when the specimens were exposed to HCl solution. In addition, the scanning electron

Development of Self-Consolidating High Strength Concrete Incorporating Treated Palm Oil Fuel Ash

Palm oil fuel ash (POFA) has previously been used as a partial cement replacement in concrete. However, limited research has been undertaken to utilize POFA in high volume in concrete. This paper presents a study on the treatment and utilization of POFA in high volume of up to 50% by weight of cement in self-consolidating high strength concrete (SCHSC). POFA was treated via heat treatment to reduce the content of unburned carbon. Ordinary Portland cement was substituted with 0%, 10%, 20%, 30%, and 50% treated POFA in SCHSC. Tests have been conducted on the fresh properties, such as filling ability, passing ability and segregation resistance, as well as compressive strength, drying shrinkage and acid attack resistance to check the effect of high volume treated POFA on SCHSC. The results revealed that compared to the control concrete mix, the fresh properties, compressive strength, drying shrinkage, and resistance against acid attack have been significantly improved. Conclusively, treated POFA can be used in high volume as a cement replacement to produce SCHSC with an improvement in its properties

Potential of Natural Fiber Reinforced Polymer Composites in Sandwich Structures: A Review on Its Mechanical Properties

The interest in using natural fiber reinforced composites is now at its highest. Numerous studies have been conducted due to their positive benefits related to environmental issues. Even though they have limitations for some load requirements, this drawback has been countered through fiber treatment and hybridization. Sandwich structure, on the other hand, is a combination of two or more individual components with different properties, which when joined together can result in better performance. Sandwich structures have been used in a wide range of industrial material applications. They are known to be lightweight and good at absorbing energy, providing superior strength and stiffness-to-weight ratios, and offering opportunities, through design integration, to remove some components from the core element. Today, many industries use composite sandwich structures in a range of components. Through good design of the core structure, one can maximize the strength properties, with a low density. However, the application of natural fiber composites in sandwich structures is still minimal. Therefore, this paper reviewed the possibility of using a natural fiber composite in sandwich structure applications. It addressed the mechanical properties and energy-absorbing characteristics of natural fiber-based sandwich structures tested under various compression loads. The results and potential areas of improvement to fit into a wide range of engineering applications were discussed