Mechanical Properties of Differently Nanostructured and High-Pressure Compressed Hydroxyapatite-Based Materials for Bone Tissue Regeneration

Hydroxyapatite (HAp) has long been considered the gold standard in the biomedical field, considering its composition and close resemblance to human bone. However, the brittle nature of hydroxyapatite (HAp) biomaterial, constrained by its low fracture toughness (of up to 1.2 vs. 2–12 MPa m1/2 of human bone), remains one of the significant factors impairing its use in bone regeneration. In the present study, HAp nanoparticles synthesized by the solid-state (SHAp) and sonochemical (EHAp) approaches using eggshell-derived calcium hydroxide and ammonium dihydrogen orthophosphate as precursors are compared with those synthesized using commercially available calcium hydroxide and ammonium dihydrogen orthophosphate as precursors (CHAp) employing sonochemical method. The HAp samples were then compressed into compact materials using a uniaxial high-pressure compression technique at a preoptimized load and subsequently characterized for mechanical properties using the Vickers indentation method and compressive strength testing. The analysis revealed that the material with smaller particle size (30–40 nm) and crystalline nature (EHAp and CHAp) resulted in mechanically robust materials (σm = 54.53 MPa and 47.72 MPa) with high elastic modulus (E = 4011.1 MPa and 2750.25 MPa) and density/hardness-dependent fracture toughness (σf = 4.34 MPa m1/2and 6.57 MPa m1/2) than SHAp (σm =28.40 MPa, E = 2116.75 MPa, σf = 5.39 MPa m1/2). The CHAp material was found to be the most suitable for applications in bone regeneration.

Indian Ocean Rim Association

The Indian Ocean Rim Association (IORA) is a regional forum that focuses on bringing together representatives of government, business, and academia, for promotion purposes. It depends on the principles of open regionalism for strengthening trade facilitation and investment, promotion, and social development of the region. Social, cultural, political, geographical, and economic linkages exist between 22 member nations. The main objective of this chapter is analyzing India's trade potential with IORA member nations. The main outcome of this chapter is that India should concentrate on ammonium dihydrogen orthophosphate for Australia, gold and semi-manufactured for Singapore, mineral or chemical fertilizers for Thailand, tankers for Malaysia, warp knit fabrics of synthetic fibers for Indonesia, ammonium dihydrogen orthophosphate for South Africa, palm oil and fractions for Sri Lanka, Bangladesh, Mozambique, Tanzania, the United Republic of Yemen, crude palm oil for Kenya, bigeye tunas, frozen for Mauritius, and carded yarn of fine animal hair for Madagascar.

Mechanical Properties and Cytotoxicity of Differently Structured Nanocellulose-hydroxyapatite Based Composites for Bone Regeneration Application

The nanocomposites were prepared by synthesizing (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibrils (TCNFs) or cellulose nanocrystals (CNCs) with hydroxyapatite (HA) in varying composition ratios in situ. These nanocomposites were first obtained from eggshell-derived calcium and phosphate of ammonium dihydrogen orthophosphate as precursors at a stoichiometric Ca/P ratio of 1.67 with ultrasonication and compressed further by a uniaxial high-pressure technique. Different spectroscopic, microscopic, and thermogravimetric analyses were used to evaluate their structural, crystalline, and morphological properties, while their mechanical properties were assessed by an indentation method. The contents of TCNF and CNC were shown to render the formation of the HA crystallites and thus influenced strongly on the composite nanostructure and further on the mechanical properties. In this sense, the TCNF-based composites with relatively higher contents (30 and 40 wt %) of semicrystalline and flexible TCNFs resulted in smoother and more uniformly distributed HA particles with good interconnectivity, a hardness range of 550–640 MPa, a compression strength range of 110–180 MPa, an elastic modulus of ~5 GPa, and a fracture toughness value of ~6 MPa1/2 in the range of that of cortical bone. Furthermore, all the composites did not induce cytotoxicity to human bone-derived osteoblast cells but rather improved their viability, making them promising for bone tissue regeneration in load-bearing applications.

Determination of Magnesium Valproate and Its Process Related Impurities by Ultraperformance Liquid Chromatography

A selective ultraperformance liquid chromatographic (UPLC) method for the determination of magnesium valproate and its process related impurities has been developed. The method includes reversed-phase Acquity BEH C18 column with 100 mm × 2.1 mm i.d. and 1.7 µ particle size. The mobile phase consists of acetonitrile and 5 mM ammonium dihydrogen orthophosphate with pH = 3.0 at 45 : 55 isocratic elution. The flow rate was set at 0.3 mL/min and UV detection was performed at 215 nm. A system suitability test (SST) was developed to govern the quality of the separation. The developed method has been validated further with respect to linearity, accuracy, precision, selectivity, LOD, LOQ, and robustness. Different batches of samples were examined using this method; the method proved to be successful when applied to analyze a marketed magnesium valproate formulation.

Degradation studies of organic acids in commercially packed fruit juices: A reverse phase high performance liquid chromatographic approach

Organic acids are important constituents of fruit juices. They render tartness, flavour and specific taste to fruit juices. Shelf life and stability of fruit juices are important factors, which determine their nutritional quality and freshness. In this view, the effect of storage on the concentration of organic acids in commercially packed fruit juices is studied by reverse phase high performance liquid chromatography (RP-HPLC). Ten packed fruit juices from two different brands are stored at 30°C for 24, 48 and 72 hours. A reverse phase high performance liquid chromatographic method is used to determine the concentration of oxalic, tartaric, malic, ascorbic and citric acid in the fruit juices during storage. The chromatographic analysis of organic acids is carried out using mobile phase 0.5% (w/v) ammonium dihydrogen orthophosphate buffer (pH 2.8) on C18 column with UV-Vis detector. The results show that the concentration of organic acids generally decreases in juices under study with the increase in storage time. All the fruit juices belonging to tropicana brand underwent less organic acid degradation in comparison to juices of real brand. Orange fruit juice is found to be least stable among the juices under study, after the span of 72 hours. Amongst all the organic acids under investigation minimum stability is shown by ascorbic acid followed by malic and citric acid.