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Experimental and numerical analyses are carried out to investigate the influence of twisted tape inserts on the heat transfer and the flow behavior in double tube heat exchangers. First, all the performance factors, namely the Nusselt number, friction factor, and thermal performance factor, were studied for a basic heat exchanger (BHE). Afterwards, twisted tapes with three different twist ratios (7.5, 6, and 4.5) were inserted inside the inner tube of the BHE, which resulted in three different modified heat exchangers (MHEs). For the numerical study, a 3D numerical model is developed with the k-ε RNG turbulent model to visualize the flow and the heat transfer behavior inside the heat exchangers. In both studies, turbulent flow field is maintained, ranging Reynolds number from 15000 to 50000. From the experimental result, an enhanced heat transfer, characterized by the performance factors, is found for all the MHEs compared to the BHE. The most enhanced thermal performance factor is achieved for the MHE with the lowest twist ratio. Finally, a good agreement between obtained numerical and experimental results reveals that the present numerical model can reliably predict the flow and heat transfer behavior in double tube heat exchangers.

Lysozyme, an anti-bacterial enzyme, is mostly found in the body fluids, various tissues and secretions of animals and humans, and confers immunity against a wide range of bacterial species. The present study was carried out to elucidate the gene sequence of this enzyme in Indian Sahiwal × Holstein Friesian crossbred cattle and to explore the polymorphism of the gene as well as their association with milk production and somatic cell traits. The total length of lysozyme cDNA was found to be of 447 bp. The similarity with Bos taurus, human, pig, monkey, gorilla, mice, rat, chicken, dog and sheep was estimated as 99.1%, 85%, 81.0%, 85.2%, 84.3%, 77.9%, 77.9%, 41.4%, 40.5% and 24.6%, respectively. Polymorphism study of two fragments, extended exon1 including promoter, exon1 and partial intron1 (268 bp), and extended exon2 including partial intron1 and 2, and exon2 region (287 bp) of milk lysozyme gene was carried out by employing single-stranded conformation polymorphism (SSCP). In the extended exon1 fragment, three alleles namely A, B and C with frequencies of 0.59, 0.28 and 0.12 were observed while in the exon extended fragment, three different alleles – P, Q and R with respective frequencies of 0.61, 0.38 and 0.01 – were determined in Indian Sahiwal × Holstein Friesian cross. A total of eight haplotypes were found in this population where the most predominant one was h1 (0.52). Genotypes of exon1 extended fragment showed significant association with total milk yield, daily milk yield, peak yield and somatic cell score at P < 0.05 while that of exon2 extended fragment had significant correlation with only total lactational milk yield. Haplotype combinations also revealed significant association with total milk production where h1h1 homozygous showed highest yield during first lactation.

Ground state properties, dispersion relations and scaling behaviour of spin gap of a bond alternating spin-1/2 anisotropic Heisenberg chain have been studied where the exchange interactions on alternate bonds are ferromagnetic (FM) and antiferromagnetic (AFM) in two separate cases. The resulting models separately represent nearest neighbour (NN) AFM-AFM and AFM-FM bond alternating chains. Ground state energy has been estimated analytically by using both bond operator and Jordan-Wigner representations and numerically by using exact diagonalization. Dispersion relations, spin gap and several ground state orders have been obtained. Dimer order and string orders are found to coexist in the ground state. Spin gap is found to develop as soon as the non-uniformity in alternating bond strength is introduced in the AFM-AFM chain which further remains non-zero for the AFM-FM chain. This spin gap along with the string orders attribute to the Haldane phase. The Haldane phase is found to exist in most of the anisotropic region similar to the isotropic point.