Removing ammonia from air with a constant pH, slightly acidic water spray wet scrubber using recycled scrubbing solution

Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high ammonia capture efficiencies; however, the high acidity created practical problems. Lower acidity solutions would reduce corrosion, maintenance, and cost; however, designers may need to use strategies for increasing scrubber effectiveness, such as using lower air velocities. The objective of this studywas to determine if a spray scrubber with slightly acidic and higher p H scrubbing solution （pH from 2 to 8） could effectively remove NH3 from NH3 laden air （such as animal building exhaust air）, and also collect this valuable resource for rater use as a fertilizer. A bench-scale spray wet scrubber treated 20 ppmv NH3/air mixture in a countercurrent contact chamber. First, the solution pH was varied from 2 to 8while maintaining constant air velocity at 1.3 m. s-1. Next, air velocity was increased （2and 3 m.s-1） while solution pH remained constant at pH6. At 1.3 m.s -1, NH3 removal efficiencies ranged between 49.0% （pH8） and 84.3% （pH2）. This study has shown that slightly acidic scrubbing solutions are a practical means of removing ammonia from air especially if the scrubber is designed to increase collisions between solution droplets and NH3 molecules. The NH3 removed from the air was held in solution as NH4＋ and accumulates over time so the solution should be an excellent fertilizer.

Estimating EC and ionic EC contribution percentage of nutrient solution based on ionic activity

The dynamic monitoring technology of inorganic ions using ion selective electrodes has some problems such as low precision,vulnerability to other ions,short service life,and high price.Due to the difficulty of dynamic control based on ionic concentration of nutrient solution,EC and pH values of nutrient solution are often used as feedback control indexes in hydroponic system.In this study,estimation algorisms of EC and ionic EC contribution percentage based on ionic activity were proposed to understand the quantitative relationship between ionic concentration and EC.With a view to predicting the EC accurately by mean ionic activities of specific salts in nutrient solution based on a specific formula,ionic concentration could also be calculated by the actual measurement of EC combined with ionic EC contribution percentage.With Japanese horticultural experimental nutrient formula and Yamasaki tomato nutrient formula,significant linear correlations between estimated EC and measured EC were found with determination coefficients over 0.99.Ionic EC contribution percentage was not affected by different relative concentrations of nutrient solutions.However,ionic EC contribution percentage changed significantly when adding specific salts with different concentrations,and different changes were found in each anions and cations of specific salt added.When the same K+concentration was added in different forms of KNO_(3),K_(2_SO_(4),KCl,and KH_(2)PO_(4),the changes of ionic EC contribution percentage of K^(+)were similar,but those of other anions in potassium salts varied greatly.The relative errors of estimated EC of nutrient solutions based on ionic activities were only 1.3%in horticultural experimental nutrient solution and 1.8%in Yamasaki tomato nutrient solution with different relative concentrations compared to measured EC.The relative errors of estimated EC of nutrient solutions with specific salt added were only 0.1%-0.5%compared to measured EC in two nutrient solution.Therefore,the dynamic feedback control of ionic concentration of nutrient solution could be realized by using EC measurement combined with ionic EC contribution percentage to improve the ionic quantitative control in nutrient solution.The EC control of nutrient solution in automatic irrigation system might be upgraded to ionic concentration control by using algorisms above of ionic EC contribution percentage and EC estimation to meet dynamic demands of hydroponic crops for ionic concentration in different growth stages.

Modeling of Cell/Dendrite Transition During Directional Solidification of Ti-Al Alloy Using Cellular Automaton Method

Solute diffusion controlled solidification model was used to simulate the initial stage cellular to dendrite transition of Ti44Al alloys during directional solidification at different velocities. The simulation results show that during this process, a mixed structure composed of cells and dendrites was observed, where secondary dendrites are absent at facing surface with parallel closely spaced dendrites, which agrees with the previous experimental observation. The dendrite spacings are larger than cellular spacings at a given rate, and the columnar grain spacing sharply increases to a maximum as solidification advance to coexistence zone. In addition, simulation also revealed that decreasing the numbers of the seed causes the trend of unstable dendrite transition to increase. Finally, the main influence factors affecting cell/dendrite transition were analyzed, which could be the change of growth rates resulting in slight fluctuations of liquid composition occurred at growth front. The simulation results are in reasonable agreement with the results of previous theoretical models and experimental observation at low cooling rates.

Nonlinear optimal predictive controller for static var compensator to improve power system damping and to maintain voltage

The main objectives of this paper are to simul-taneously improve power system damping and to maintain voltage at the static var compensator(SVC)location bus simultaneously.A new controller for SVC with closed-form analytic solution nonlinear optimal predictive control(NOPC)law was presented.The controller does not require online optimization and the huge calculation burden can be avoided,so that the demand of real-time control can be sat-isfied.In addition,there are only two design parameters,which are the predictive period and control order;so it is easy to implement and test in practical use.Simulation results have shown that the controller can not only attenuate power system oscillation effectively but can also maintain voltage at the SVC bus location.

Immunogenic-cell-killing and immunosuppression-inhibiting nanomedicine

Combining chemo-therapeutics with immune checkpoint inhibitors facilitates killing cancer cells and activating the immune system through inhibiting immune escape.However,their treatment effects remain limited due to the compromised accumulation of both drugs and inhibitors in certain tumor tissues.Herein,a new poly(acrylamide-co-acrylonitrile-co-vinylimidazole-co-bis(2-methacryloyl)oxyethyl disulfide)(PAAVB)polymer-based intelligent platform with controllable upper critical solution temperature(UCST)was used for the simultaneous delivery of paclitaxel(PTX)and curcumin(CUR).Additionally,a hyaluronic acid(HA)layer was coated on the surface of PAAVB NPs to target the CD44-overexpressed tumor cells.The proposed nanomedicine demonstrated a gratifying accumulation in tumor tissue and uptake by cancer cells.Then,the acidic microenvironment and high level of glutathione(GSH)in cancer cells could spontaneously decrease the UCST of polymer,leading to the disassembly of the NPs and rapid drug release at body temperature without extra-stimuli.Significantly,the released PTX and CUR could induce the immunogenic cell death(ICD)to promote adaptive anti-tumor immunogenicity and inhibit immunosuppression through suppressing the activity of indoleamine 2,3-dioxygenase 1(IDO1)enzyme respectively.Therefore,the synergism of this intelligent nanomedicine can suppress primary breast tumor growth and inhibit their lung metastasis.