Over the past two decades, active interest has been generated and it continues to grow in the chemistry of iron compounds, particularly in expanding areas of synthesis of heterobinuclear complexes. Moreover it is substantiated by the large-scale industrial and biochemical applications. In addition to synthesis studies, extensive investigations were also carried out to establish structural-reactive site correlation. Fascinatingly, crystallographic data of around 900 heterometallic dimers have shown approximately 7.8% of them exist as isomers and often stereoselectivity of such isomers is linked to stereospecificity in biological reactions. In the first paper, “Isomers in the Chemistry of Heterometallic Iron Clusters: Part I Heterometallic Dimers”, the authors Milan Melník and Mária Kohútová have analyzed crystallographic and structural data of many organometallic distortion isomers. Detailed studies indicate that the factors like solution concentration, nature of solvent, pH, temperature, pressure and mole ratio greatly affect the composition and structure of heterobinuclear complexes of iron.

In refineries, petroleum derivatives are continuously converted into lighter, more valuable products via high temperature catalytic cracking in the Fluid Catalytic Cracking (FCC) unit. Representative FCC products are propylene, butylenes, gasoline, naptha, coke, and dry gas. Operating conditions of FCCs vary depending upon the feed, desired products and mechanical limitations. FCC catalyst is a very porous material that has matrix-like zeolites. Nowadays, two basic types of FCC units are commonly used in refineries—‘side-by-side’ type and the orthoflow or ‘stacked’ type. The stacked type FCC unit is designed to operate with only a single stage of regeneration and has no provision for external heat removal from the catalyst. The second paper, “Stacked Configuration of Fluidized Catalytic Cracking Unit: A Review”, by Diwakar Z Shende and Kailas L Wasewar, explains the advantages of stacked configuration over side-by-side configuration. The inherent superiorities like less power consumption and less requirement of space can make it a preferred choice.

Soy products are an excellent source of dietary proteins amongst legumes. Soy is rich in minerals such as calcium, magnesium, zinc, cobalt and potassium; vitamins like thiamin (B1) and riboflavin (B2); and minor components such as protease inhibitors, phenolic compounds and lectin thus making soy products healthy and nutritious. Tofu or ‘bean curd’ resembles a soft white cheese and is prepared directly from soybeans using salt, acid or proteolytic enzymes by the coagulation of soy protein gel with water, soy lipids and other constituents trapped in its gel. The third paper, “Biochemical Mechanism of Soy Protein Gelation and Factors Influencing Tofu Characteristics”, by M K Tripathi, Punit Chandra and L K Sinha, describes several quality controlling parameters such as soybean variety, nature of coagulant, concentration of coagulant, process of mixing, coagulation time and temperature for good quality and yield of tofu.

Recent advances in the tailor-made designer modified oligodeoxynucleotides have a number of applications. Many modified oligodeoxynucleotides are now amply used as probes in biochemistry and molecular biology labs, as therapeutic agents targeted to human disease, in molecular diagnostic strategies for identifying disease-related genes and pathogens. Thermal melting (Tm) studies have established that modifications may significantly stabilize the DNA/DNA duplexes. Interestingly, the last paper,“C-5 Thiopropyne-Substituted Thymidine Containing Oligodeoxynucleotide: DNA/DNA Duplex Formation”, by Ajay Kumar, reports the DNA/DNA duplex formation hybridization studies of disulfide containing oligodeoxynucleotide with its complementary oligodeoxynucleotide and mismatch containing oligodeoxynucleotides. It is expected that such binding studies of the modified oligodeoxynucleotide can give better insight into altered base pairing selectivity and increasing duplex stability.

-- Sushama Viladkar
Consulting Editor