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Abstract The inner tubes of double-side heating once-through steam generator (OTSG) with helical tubes are spiral channels, and the secondary fluid is heated on both sides, effectively improving the heat transfer efficiency. The spiral structure makes its flow heat transfer characteristics different from straight tube type OTSG. This article establishes a numerical model of Euler two-phase flow in double-side heating OTSG with helical tubes to analyze its velocity distribution, volume fraction distribution, and temperature distribution. The results show that the fluid spirally rises in the secondary flow passage, the velocity of two phases increases rapidly after vaporization, the slip ratio is greater than 1, the steam volume fraction on the wide side is higher than that on the narrow side, and the steam volume fraction presents a spiral distribution on the wall. The non-uniform circumferential steam volume fraction leads to the wall dryout first at the wide edge, and the wall temperature also presents a spiral distribution. The dryout position temperature rises 40.13 K along the Z direction, and the temperature gradient is 5.26 K/mm. The circumferential temperature rises 44.46 K, and the temperature gradient is 15.11 K/mm. [ABSTRACT FROM AUTHOR]

Neuropeptides are key signaling molecules in the endocrine and nervous systems that regulate many critical physiological processes. Understanding the functions of neuropeptides in vivo requires the ability to monitor their dynamics with high specificity, sensitivity, and spatiotemporal resolution. However, this has been hindered by the lack of direct, sensitive, and noninvasive tools. We developed a series of GRAB (G protein-coupled receptor activation‒based) sensors for detecting somatostatin (SST), corticotropin-releasing factor (CRF), cholecystokinin (CCK), neuropeptide Y (NPY), neurotensin (NTS), and vasoactive intestinal peptide (VIP). These fluorescent sensors, which enable detection of specific neuropeptide binding at nanomolar concentrations, establish a robust tool kit for studying the release, function, and regulation of neuropeptides under both physiological and pathophysiological conditions.

Lysis is a common functional module in synthetic biology and is widely used in genetic circuit design. Lysis could be achieved by inducing expression of lysis cassettes originated from phages. However, detailed characterization of lysis cassettes hasn't been reported yet. Here, we first adopted arabinose- and rhamnose-inducible systems to develop inducible expression of five lysis cassettes ( S 105 , A52G , C51S S76C , LKD , LUZ ) in Escherichia coli Top10. By measuring OD 600 , we characterized the lysis behavior of strains harboring different lysis cassettes. These strains were harvested at different growth stages, induced with different concentrations of chemical inducers, or contained plasmids with different copy numbers. We found that although all five lysis cassettes could induce bacterial lysis in Top10, lysis behaviors differed a lot at various conditions. We further found that due to the difference in background expression levels between strain Top10 and Pseudomonas aeruginosa PAO1, it was hard to construct inducible lysis systems in strain PAO1. The lysis cassette controlled by rhamnose-inducible system was finally inserted into the chromosome of strain PAO1 to construct lysis strains after careful screen. The results indicated that LUZ and LKD were more effective in strain PAO1 than S 105 , A52G and C51S S76C . At last, we constructed an engineered bacteria Q16 using an optogenetic module BphS and the lysis cassette LUZ . The engineered strain was capable of adhering to target surface and achieving light-induced lysis by tuning the strength of ribosome binding sites (RBSs), showing great potential in surface modification.