A potential theory for the k-curvature equation

In this paper, we introduce a potential theory for the k-curvature equation, which can also be seen as a PDE approach to curvature measures. We assign a measure to a bounded, upper semicontinuous function which is strictly subharmonic with respect to the k-curvature operator, and establish the weak continuity of the measure

Net charge fluctuation and string fragmentation

We present simulation results of net charge fluctuation in $Au+Au$ collisions at $\sqrt{s_{nn}}$=130 GeV from a dynamic model, JPCIAE. The calculations are done for the quark-gluon phase before hadronization, the pion gas, the resonance pion gas from $\rho$ and $\omega$ decays and so on. The simulations of the charge fluctuation show that the discrepancy exists between the dynamic model and the thermal model for a pion gas and a resonance pion gas from $\rho$ and $\omega$ decays while the simulated charge fluctuation of the quark-gluon phase is close to the thermal model prediction. JPCIAE results of net charge fluctuation in the hardonic phase are nearly 4-5 times larger than one for the quark-gluon phase, which implies that the charge fluctuation in the quark-gluon phase may not survive the hadronization (string fragmentation) as implemented in JPCIAE.Comment: 9 pages, 3 figure

The optimization of ejector geometry for mixing NaOH powders with water in on-board carbon solidification system

Owing to increasing requirement of greenhouse gas emissions reductions, researchers all over the world has been investigating and developing technology applying to all different sectors. According to the report from International Maritime Organization (IMO), the international shipping has contributed 2.2% of global carbon emissions in 2012. To mitigate this situation, organizations, researchers and engineers are striving to reduce the emissions by increasing the energy efficiency or applying emission reduction regulations and techniques. Authors has investigated a chemical absorption method to absorb and solidify the carbon content in the exhaust gases from ships. In the chemical absorption method, to absorb the carbon dioxide from exhaust gases, sodium hydroxide (NaOH) solution is applied as absorbent. However, the storage of NaOH solution may cause stability and corrosion problems on ships. To eliminate these problem, this paper introduce the ejector technology to mix NaOH powders with water to supply and replenish absorbent to the system which will reduce the storage of NaOH solution and instead only NaOH powders should be stored on board. This paper also investigates the impact of swapping fluid inlets to determine a preferred design. With the application of design of experiment and computing fluid dynamic, the optimization of the preferred design is also carried out in order to determine an optimal design of the ejector geometry

Microbial communities and arsenic biogeochemistry at the outflow of an alkaline sulfide-rich hot spring.

Alkaline sulfide-rich hot springs provide a unique environment for microbial community and arsenic (As) biogeochemistry. In this study, a representative alkaline sulfide-rich hot spring, Zimeiquan in the Tengchong geothermal area, was chosen to study arsenic geochemistry and microbial community using Illumina MiSeq sequencing. Over 0.26 million 16S rRNA sequence reads were obtained from 5-paired parallel water and sediment samples along the hot spring's outflow channel. High ratios of As(V)/AsSum (total combined arsenate and arsenite concentrations) (0.59-0.78), coupled with high sulfide (up to 5.87 mg/L), were present in the hot spring's pools, which suggested As(III) oxidation occurred. Along the outflow channel, AsSum increased from 5.45 to 13.86 μmol/L, and the combined sulfide and sulfate concentrations increased from 292.02 to 364.28 μmol/L. These increases were primarily attributed to thioarsenic transformation. Temperature, sulfide, As and dissolved oxygen significantly shaped the microbial communities between not only the pools and downstream samples, but also water and sediment samples. Results implied that the upstream Thermocrinis was responsible for the transformation of thioarsenic to As(III) and the downstream Thermus contributed to derived As(III) oxidation. This study improves our understanding of microbially-mediated As transformation in alkaline sulfide-rich hot springs