Obstacle-induced giant jammed aggregation of active semiflexible filaments.

Filaments driven by bound motor proteins and chains of self-propelled colloidal particles are a typical example of active polymers (APs). Due to deformability, APs exhibit very rich dynamic behaviors and collective assembling structures. Here, we are concerned with a basic question: how APs behave near a single obstacle? We find that, in the presence of a big single obstacle, the assembly of APs becomes a two-state system, i.e. APs either gather nearly completely together into a giant jammed aggregate (GJA) on the surface of the obstacle or distribute freely in space. No partial aggregation is observed. Such a complete aggregation/collection is unexpected since it happens on a smooth convex surface instead of, e.g., a concave wedge. We find that the formation of a GJA experiences a process of nucleation and the curves of the transition between the GJA and the non-aggregate state form hysteresis-like loops. Statistical analysis of massive data on the growing time, chirality and angular velocity of both the GJAs and the corresponding nuclei shows the strong random nature of the phenomenon. Our results provide new insights into the behavior of APs in contact with porous media and also a reference for the design and application of polymeric active materials.

Pilot-scale study of forward osmosis for treating desulfurization wastewater.

Forward osmosis (FO) treatment of desulfurization wastewater shows great potential in laboratory scale tests. To explore the adaptability of the forward osmosis system in the practical treatment of desulfurization wastewater, we carried out a pilot test on desulfurization wastewater treated by the traditional method under the conditions of adding soda ash (SA) and adding FO scale inhibitor (FOSI). The results showed that the FO system could concentrate desulfurization wastewater with an average TDS of 15,816-32,820 mg/L in the influent water to an average TDS of more than 120,000 mg/L, which was concentrated 3.8-7.8 times. The removal rates of Ca2+, Mg2+ and Cl- were more than 99% and the system could operate stably for a long time. Under the condition of adding SA and FOSI, the system recovery rate was 85.38% and 73.02%, respectively. The operating cost was 25 RMB/ton and 21.77 RMB/ton, respectively. The results showed that the application of forward osmosis in desulfurization wastewater treatment was technically feasible and economically effective.

Optimal design of a multi-dimensional validated synergistic extraction process for the treatment of atmosphere-vacuum distillation wastewater.

The wastewater discharged from atmosphere-vacuum distillation of oil refining process contains a high concentration of phenolic compounds, which are toxic and not eco-friendly. Direct discharge of the untreated wastewater will have an adverse impact on the surrounding environment. This paper proposes a multi-dimensional synergistic extraction solution to realize the effective disposal of atmosphere-vacuum distillation wastewater. Firstly, extraction experiments are conducted to select the optimal extractant. Secondly, the microscopic mechanism of separating phenolic compounds from wastewater with synergistic extractant of methyl isobutyl ketone and n-pentanol is investigated by molecular dynamics simulation. Finally, the synergistic extraction process is modeled and optimized based on above multi-dimensional analyses. The optimization is performed through sensitivity analysis from three aspects: operating parameters, synergistic extractant cycling, and waste heat recovery. A control scheme is then designed to maintain the smooth operation of synergistic extraction process. Feed disturbances are specifically added to test the anti-interference capability of the control scheme. With the novel treatment process proposed in this paper, the removal rate of phenolic compounds from atmosphere-vacuum distillation wastewater reaches 93.02%.

Comprehensive analysis of important parameters of choline chloride-based deep eutectic solvent pretreatment of lignocellulosic biomass.

Choline chloride based deep eutectic solvents have showed great potential in lignocellulosic biomass pretreatment. In this study, for DES pretreatment with different hydrogen bond donners of different raw materials under different reaction conditions, multivariate analysis methods including principal component analysis and partial least squares analysis were used for reveal the pretreatment mechanism by evaluating the inner relationships among 42 key process factors. Furthermore, based on molecular simulation, the detailed relationships between key variables were further analyzed. Meanwhile, four-dimensional color graphs were used to intuitively reveal the synergistic influence of multivariate conditions variables on pretreatment effect to obtain better economic benefits and energy consumption indicators for DES pretreatment. The results showed that HBD hydrophilic ability, HBD polarity, HBD acidity, HBD ability to form hydrogen bonds, molar ratio of HBD to choline chloride and pretreatment severity had great influence on the Choline chloride based deep eutectic solvents pretreatment effect.

Key process parameters for deep eutectic solvents pretreatment of lignocellulosic biomass materials: A review.

Deep eutectic solvent (DES) has been considered as a novel green solvent for lignocellulosic biomass pretreatment. The efficiency of DES pretreatment is affected by the synergy of various process parameters. The study of effect of DES physicochemical properties and pretreatment reaction conditions on the mechanism of lignocellulose biomass fractionation was of great significance for the development of biomass conversion. Form the view of process control, this review summarized recent advances in DES pretreatment, analyzed the challenges, and prospected the future development of this research field.

Effect of crystallinity on pretreatment and enzymatic hydrolysis of lignocellulosic biomass based on multivariate analysis.

In this work, multivariate data analysis was employed to correlate variables of pretreatment process of lignocellulosic biomass. Principal component analysis and partial least square methods were performed to get the inner-relationship and data interpretation between the crystallinity and other parameters of mechanical refining-assisted sodium hydroxide pretreatment followed by enzymatic saccharification of corn stover. The PCA and PLS models showed that Sodium hydroxide dosage, mechanical refining treatment, lignin removal rate and crystallinity had close inner-related relationship with the efficiency of pretreatment and enzymolysis. Alkaline reaction and mechanical refining treatment had strong influence on the crystallinity. Multivariate data analysis revealed that pretreated corn stover samples with lower crystallinity were more easily hydrolyzed by enzyme and could get more final reducing sugar. This work could offer a new methodology to get further understanding of effect of crystallinity on the crop residue lignocellulosic biomass conversion process.

Polymer-Nucleic Acid Interactions.

Gene therapy is an important therapeutic strategy in the treatment of a wide range of genetic disorders. Polymers forming stable complexes with nucleic acids (NAs) are non-viral gene carriers. The self-assembly of polymers and nucleic acids is typically a complex process that involves many types of interaction at different scales. Electrostatic interaction, hydrophobic interaction, and hydrogen bonds are three important and prevalent interactions in the polymer/nucleic acid system. Electrostatic interactions and hydrogen bonds are the main driving forces for the condensation of nucleic acids, while hydrophobic interactions play a significant role in the cellular uptake and endosomal escape of polymer-nucleic acid complexes. To design high-efficiency polymer candidates for the DNA and siRNA delivery, it is necessary to have a detailed understanding of the interactions between them in solution. In this chapter, we survey the roles of the three important interactions between polymers and nucleic acids during the formation of polyplexes and summarize recent understandings of the linear polyelectrolyte-NA interactions and dendrimer-NA interactions. We also review recent progress optimizing the gene delivery system by tuning these interactions.

High concentration powdered activated carbon-membrane bioreactor (PAC-MBR) for slightly polluted surface water treatment at low temperature.

In this study, different concentrations of PAC combined with MBR were carried out to treat slightly polluted surface water (SPSW) at low temperature (10°C). Effects of PAC on the efficiencies of operation, treatment, and the performance of the process were investigated. It was found that the effluent quality, performance efficiency, resistance of shock load were all enhanced and chemical irreversible membrane fouling was reduced with increasing dosage of PAC in MBR. Only when the concentration of PAC which acted as biological carriers was high enough (i.g., 50 g/L), nitrification without initial inoculation in the filtration tank could start within 19 days and be completed within 35 days at 10°C. Fifty grams per liter PAC was the optimal dosage in MBR for stable and extended operation. Under this condition, mean removal efficiencies of ammonia nitrogen (NH(3)-N), dissolved organic carbon (DOC) and UV(254) were 93%, 75%, and 85%, respectively.