Economic Evaluation of an Ammonia-Fueled Ammonia Carrier Depending on Methods of Ammonia Fuel Storage

This study proposed two concepts for ammonia fuel storage for an ammonia-fueled ammonia carrier and evaluated these concepts in terms of economics. The first concept was to use ammonia in the cargo tank as fuel and the second concept was to install an additional independent fuel tank in the vessel. When more fuel tanks were installed, there was no cargo loss. However, there were extra costs for fuel tanks. The target ship was an 84,000 m3 ammonia carrier (very large gas carrier, VLGC). It traveled from Kuwait to South Korea. The capacity of fuel tanks was 4170 m3, which is the required amount for the round trip. This study conducted an economic evaluation to compare the two proposed concepts. Profits were estimated based on sales and life cycle cost (LCC). Results showed that sales were USD 1223 million for the first concept and USD 1287 million for the second concept. Profits for the first and second concepts were USD 684.3 million and USD 739.5 million, respectively. The second concept showed a USD 53.1 million higher profit than the first concept. This means that the second concept, which installed additional independent fuel tanks was better than the first concept in terms of economics. Sensitivity analysis was performed to investigate the influence of given parameters on the results. When the ammonia fuel price was changed by ±25%, there was a 15% change in the profits and if the ammonia (transport) fee was changed by ±25%, there was a 45% change in the profits. The ammonia fuel price and ammonia (cargo) transport fee had a substantial influence on the business of ammonia carriers.

Ammonia Stress Coping Strategy in a Highly Invasive Ascidian

The outbreak of invasive ascidian Molgula manhattensis has negatively affected marine and coastal ecosystems and caused huge economic loss in various industries such as aquaculture. In mariculture systems usually characterized by high ammonia nitrogen, the capacity of M. manhattensis to defend against drastic ammonia elevation plays a crucial role in its survival and subsequent invasions. However, ammonia coping strategies and associated genes/proteins remain largely unknown. Here we investigated rhesus glycoproteins (Rh)-mediated ammonia transport by identifying all Rh proteins and exploring their mRNA expression regulations under ammonia stress. Three types of primitive Rh proteins were identified, and all contained conserved amino acid residues and functional domains. Ammonia stress largely suppressed the expression of immune-related genes, but rapidly induced the increased expression of Rh genes. Ammonia was converted into glutamine as indicated by the increased expression of glutamine synthetase gene, rather than urea as illustrated by the stable expression of arginase gene. Collectively, M. manhattensis mitigates ammonia challenge by enhancing ammonia excretion through Rh channels and detoxifying ammonia into glutamine. Our results provide insights into the molecular mechanisms underlying high tolerance and invasion success to high ammonia environments by invasive ascidians.

A Mathematical Model of the Rat Kidney. III. Ammonia Transport

Ammonia generated within the kidney is partitioned into a urinary fraction (the key buffer for net acid excretion), and an aliquot delivered to the systemic circulation. The physiology of this partitioning has yet to be examined in a kidney model, and that is undertaken in this work. This involves explicit representation of the cortical labyrinth, so that cortical interstitial solute concentrations are computed, rather than assigned. A detailed representation of cortical vasculature has been avoided by making the assumption that solute concentrations within interstitium and peritubular capillaries are likely to be identical, and that there is little to no modification of venous composition as blood flows to the renal vein. The model medullary ray has also been revised to include a segment of proximal straight tubule, which supplies ammonia to this region. The principal finding of this work is that cortical labyrinth interstitial ammonia concentration is likely to be several-fold higher than systemic arterial ammonia. This elevation of interstitial ammonia enhances ammonia secretion in both PCT and DCT, with uptake by Na,K-ATPases of both segments. Model prediction of urinary ammonia excretion is concordant with measured values, but at the expense of greater ammoniagenesis, with high rates of renal venous ammonia flux. This derives from a limited capability of the model medulla to replicate the high interstitial ammonia concentrations that are required to drive collecting duct ammonia secretion. Thus, renal medullary ammonia trapping appears key to diverting ammonia from renal vein to urine, but capturing the underlying physiology remains a challenge.

The nodule-specific multifunctional channel NOD26 of Medicago truncatula is crucial for nitrogen-fixing symbiosis

The multifunctional channel NOD26, identified and extensively studied (both biochemically and biophysically) in soybean, is a major protein component of the symbiosome membrane. The water and ammonia transport activities of NOD26 are thought to be important for nodule development, osmotic balance, and ammonia efflux from the symbiosome. However, the widely accepted relevance of NOD26 in nitrogen-fixing symbiosis has never been explored in planta. Recently, we have reported the emergence of NOD26 in the nitrogen-fixing clade of angiosperms via tandem duplication. Here, we characterized the two copies of NOD26 from Medicago truncatula (Medtr8g087710 and Medtr8g087720) in their transport abilities, and at gene expression and genetic levels. Similar to their homologous soybean gene, MtNOD26 genes encode water and ammonia transport activities in heterologous expression systems. By using multiple transcriptional studies (RT-qPCR, transcriptional fusion and RNA-Seq analyses), we found that the expression of MtNOD26 copies is restricted to the nodule and gradually increases from the bacteria-free meristematic region to the nitrogen-fixation zone. Under nitrogen-limiting soil conditions, the homozygous insertional mutant lines of these two MtNOD26 genes had the same aberrant nodulation phenotype and chlorosis. Similar to uninoculated wild-type plants, inoculated mutants were unable to grow in minimal medium without a nitrogen source. Collectively, our findings suggest functional equivalence between MtNOD26 copies and underline a crucial role of NOD26 in symbiotic nitrogen fixation.

“Mushballs” May Drive Ammonia Transport on Jupiter

Hail might account for observed depletions of ammonia in the planet’s atmosphere.

Impacts of Tide Gate Modulation on Ammonia Transport in a Semi-closed Estuary during the Dry Season—A Case Study at the Lianjiang River in South China

Recovery of tide-receiving is considered to improve the water quality in the Lianjiang River, a severely polluted and tide-influenced river connected to the South China Sea. A tide-receiving scenario, i.e., keeping the tide gate open, is compared with the other scenario representing the non-tide-receiving condition, i.e., blocking the tide flow during the flood phase, by numerical simulations based on the EFDC (Environmental Fluid Dynamics Code) model. The impacts of tide receiving were evaluated by the variation in the concentration of ammonia and its exporting fluxes, mainly in the downstream part of the river. With more water mass coming into the river, in the tide-receiving scenario, the averaged concentration of ammonia reduced by 20–40%, with the most significant decrease of 0.64 g m−3. However, the exporting flux of ammonia has decreased in the tide-receiving scenario, as the consequence of the back–forth oscillation of tidal current. In the tide-receiving scenario, the time series of ammonia concentration approximately followed the tidal oscillation, with increased concentration during the ebb tide and reduction in the flood tide. In the non-tide-receiving scenario, the ammonia concentration decreases when the tide gate is open which results in further intrusion of seawater. This was followed by an increase in ammonia concentration again after the currents shift seaward and water mass with higher concentration from the upstream part is transported downstream. Given the identical ammonia input and river runoff, the ammonia concentration stays lower in the tide-receiving scenario, except for short periods after the tide gate opening and neap tides in the downstream part which lasts for around half a day. This study highlights the importance of hydrodynamic condition, specifically tidal oscillation, in the semi-diurnal and fortnight cycles, for the transportation of waterborne materials. Furthermore, the operation of the tide gate was additionally discussed based on potential varied practical conditions and evaluation criteria.

The TRPV3 channel of the bovine rumen: localization and functional characterization of a protein relevant for ruminal ammonia transport

Large quantities of ammonia (NH3 or NH4+) are absorbed from the gut, associated with encephalitis in hepatic disease, poor protein efficiency in livestock, and emissions of nitrogenous climate gasses. Identifying the transport mechanisms appears urgent. Recent functional and mRNA data suggest that absorption of ammonia from the forestomach of cattle may involve TRPV3 channels. The purpose of the present study was to sequence the bovine homologue of TRPV3 (bTRPV3), localize the protein in ruminal tissue, and confirm transport of NH4+. After sequencing, bTRPV3 was overexpressed in HEK-293 cells and Xenopus oocytes. An antibody was selected via epitope screening and used to detect the protein in immunoblots of overexpressing cells and bovine rumen, revealing a signal of the predicted ~ 90 kDa. In rumen only, an additional ~ 60 kDa band appeared, which may represent a previously described bTRPV3 splice variant of equal length. Immunohistochemistry revealed staining from the ruminal stratum basale to stratum granulosum. Measurements with pH-sensitive microelectrodes showed that NH4+ acidifies Xenopus oocytes, with overexpression of bTRPV3 enhancing permeability to NH4+. Single-channel measurements revealed that Xenopus oocytes endogenously expressed small cation channels in addition to fourfold-larger channels only observed after expression of bTRPV3. Both endogenous and bTRPV3 channels conducted NH4+, Na+, and K+. We conclude that bTRPV3 is expressed by the ruminal epithelium on the protein level. In conjunction with data from previous studies, a role in the transport of Na+, Ca2+, and NH4+ emerges. Consequences for calcium homeostasis, ruminal pH, and nitrogen efficiency in cattle are discussed.