Energy Optimization via Process Modification To Maximize Economic Feasibility of the Butane Gas-Splitting Process

Gas splitting is an energy-intensive process that is widely used in the chemical industry. Consequently, the cost effectiveness of this process can be maximized through energy optimization. This study focuses on the energy optimization of the commercial mixed butane gas-splitting technique via process modification. Because the previous process is impeded by the instability of the n-butane content in the feedstock, it consumes excessive energy and results in a product that is inferior in purity. Therefore, we initially simulated the previously used process model and then modified this process to achieve the target purity of the product and minimize energy consumption. The energy optimization model was designed in accordance with the standards of the commercial-grade product. After achieving energy optimization, we conducted economic analyses for the two modified processes by considering their capital and operating costs. Each modified process exhibited an approximate reduction of 19.67-21.85% in its energy consumption; however, only one of the two modified processes managed to enhance the product yield (by 1.00%). The net present value of the previous process model was 126.98 M$, whereas those of the modified processes were calculated to be 134.71 and 133.78 M$

Unequal V-H gene rearrangement frequency within the large V(H)7183 gene family is not due to recombination signal sequence variation, and mapping of the genes shows a bias of rearrangement based on chromosomal location

International audienceMuch of the nonrandom usage of V, D, and J genes in the Ab repertoire is due to different frequencies with which gene segments undergo V(D)J rearrangement. The recombination signal sequences flanking each segment are seldom identical with consensus sequences, and this natural variation in recombination signal sequence (RSS) accounts for some differences in rearrangement frequencies in vivo. Here, we have sequenced the RSS of 19 individual VH 7183 genes, revealing that the majority have one of two closely related RSS. One group has a consensus heptamer, and the other has a nonconsensus heptamer. In vitro recombination substrate studies show that the RSS with the nonconsensus heptamer, which include the frequently rearranging 81X, rearrange less well than the RSS with the consensus heptamer. Although 81X differs from the other 7183-I genes at three positions in the spacer, this does not significantly increase its recombination potency in vitro. The rearrangement frequency of all members of the family was determined in mMT mice, and there was no correlation between the in vitro recombination potential and VH gene rearrangement frequency in vivo. Furthermore, genes with identical RSS rearrange at different frequencies in vivo. This demonstrates that other factors can override differences in RSS potency in vivo. We have also determined the gene order of all VH 7183 genes in a bacterial artificial chromosome contig and show that most of the frequently rearranging genes are in the 3* half of the region. This suggests that chromosomal location plays an important role in nonrandom rearrangement of the VH 7183 genes