Enhancing continuous reactive crystallization of lithium carbonate in multistage mixed suspension mixed product removal crystallizers with pulsed ultrasound.

In this work, pulsed ultrasound was used to facilitate steady-state reactive crystallization and increase the final yield and productivity of lithium carbonate in continuously operated single and multistage mixed suspension mixed product removal (MSMPR) crystallizers. Experimental analyses of the stirred tank MSMPR cascade were performed to investigate the effects of ultrasound field, residence time and temperature which contributed to the steady-state yield, crystal size distribution and crystal morphology. The results show that pulsed ultrasound can not only significantly enhance the reaction rate, but also help to improve the particle size distribution and the crystal habit. Subsequently, a population balance model was developed and applied to estimate the final yield of the continuous process of the lithium bicarbonate thermal decomposition reaction coupling lithium carbonate crystallization. The consistency of the final yield between the experiments and the simulations proved the reliability of the established model. Through the experimental and simulation analyses, it is demonstrated that the use of pulsed ultrasound, higher final stage temperature, MSMPR cascade design and appropriate residence time help to achieve higher yield and productivity. Furtherly, based on the conclusion drawn, pulsed ultrasound enhanced three-stage MSMPR cascaded lithium carbonate continuous crystallization processes were designed, and the maximum productivity of 44.0 g/h was obtained experimentally.

Effect of pH on elemental sulfur conversion and microbial communities by autotrophic simultaneous desulfurization and denitrification.

pH has an important influence on the elemental sulfur accumulated in an autotrophic simultaneous desulfurization and denitrification process. The influent nitrate to sulfide (N/S) mole ratio was set to 0.5, 0.67, 1.0, 1.33 and 2.0 with a 200 mg/L sulfide concentration. The effect of pH on elemental sulfur conversion and microbial communities was studied. Sulfide removal was achieved to the extent of 98% under near-neutral and weak base conditions after 24 h of reaction. The conversion rate of elemental sulfur was 29.41% under the near-neutral condition. The weak base condition led to greater formation of sulfate, and the nitrate used by the microorganisms was transformed mainly to N2 with a removal rate of 96%. Increasing the retention time from 24 to 48 h caused the removal rate of nitrate increased from 63.58% to 90% under the near-neutral condition. Sulfurovum sp. was the functioning bacterial species, and bands 1 and 2 represent different species of Sulfurovum sp. in the system according to the PCR-DGGE analysis of the microbial community structure. The functional bacteria represented by band 1 produced mainly sulfate, but the functional bacteria represented by band 2 produced mainly elemental sulfur.

Evaluating the Pros and Cons of Different Peer Review Policies via Simulation.

In the academic world, peer review is one of the major processes in evaluating a scholars contribution. In this study, we are interested in quantifying the merits of different policies in a peer review process, such as single-blind review, double-blind review, and obtaining authors feedback. Currently, insufficient work has been undertaken to evaluate the benefits of different peer review policies. One of the major reasons for this situation is the inability to conduct any empirical study because data are presently unavailable. In this case, a computer simulation is one of the best ways to conduct a study. We perform a series of simulations to study the effects of different policies on a peer review process. In this study, we focus on the peer review process of a typical computer science conference. Our results point to the crucial role of program chairs in determining the quality and diversity of the articles to be accepted for publication. We demonstrate the importance of discussion among reviewers, suggest circumstances in which the double-blind review policy should be adopted, and question the credibility of the authors feedback mechanism. Finally, we stress that randomness plays an important role in the peer review process, and this role cannot be eliminated. Although our model may not capture every component of a peer review process, it covers some of the most essential elements. Thus, even the simulation results clearly cannot be taken as literal descriptions of an actual peer review process. However, we can at least still use them to identify alternative directions for future study.