Reconfigurable Digital Satellite-Borne Base Station Design and Virtual Function Fast Migration Algorithm.

A breakthrough in the technology for virtualizing satellite-borne networks and computing and storage resources can significantly increase the processing capacity and resource utilization efficiency of satellite-borne base stations in response to the development trend in multi-star and multi-system converged satellite internet iterative systems. The protocol processing function of traditional satellite communication systems is generally placed in the ground station system for processing, with poor flexibility and low efficiency. As a result, a reconfigurable digital satellite-borne base station architecture design is suggested, allowing for separation of the hardware and software of the satellite-borne base station and flexible programming and dynamic loading of the satellite-borne base station's functions by software. Meanwhile, a fast adaptive migration algorithm based on multi-dimensional environment awareness is proposed on top of the reconfigurable digital base station, and migration precomputation and real-time computation are added in order to realize rapid deployment of the digital base station system network. Simulation results demonstrate the effectiveness of the proposed algorithm in enhancing system stability and decreasing real-time calculation costs associated with system network migration under conditions of high dynamic changes for each network element in a star-loaded environment. In conclusion, a digital satellite-borne base station system that effectively addresses the issues of low flexibility and high dynamic changes of nodes in the resource-constrained satellite environment can be created by combining the adaptive migration algorithm and the reconfigurable digitized satellite-borne base station architecture.

Confined water-encapsulated activated carbon for capturing short-chain perfluoroalkyl and polyfluoroalkyl substances from drinking water.

The global ecological crisis of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in drinking water has gradually shifted from long-chain to short-chain PFASs; however, the widespread established PFAS adsorption technology cannot cope with the impact of such hydrophilic pollutants given the inherent defects of solid-liquid mass transfer. Herein, we describe a reagent-free and low-cost strategy to reduce the energy state of short-chain PFASs in hydrophobic nanopores by employing an in situ constructed confined water structure in activated carbon (AC). Through direct (driving force) and indirect (assisted slip) effects, the confined water introduced a dual-drive mode in the confined water-encapsulated activated carbon (CW-AC) and completely eliminated the mass transfer barrier (3.27 to 5.66 kcal/mol), which caused the CW-AC to exhibit the highest adsorption capacity for various short-chain PFASs (C-F number: 3-6) among parent AC and other adsorbents reported. Meanwhile, benefiting from the chain length- and functional group-dependent confined water-binding pattern, the affinity of the CW-AC surpassed the traditional hydrophobicity dominance and shifted toward hydrophilic short-chain PFASs that easily escaped treatment. Importantly, the ability of CW-AC functionality to directly transfer to existing adsorption devices was verified, which could treat 21,000 bed volumes of environment-related high-load (~350 ng/L short-chain PFAS each) real drinking water to below the World Health Organization's standard. Overall, our results provide a green and cost-effective in situ upgrade scheme for existing adsorption devices to address the short-chain PFAS crisis.

Cactus-Inspired Janus Membrane with a Conical Array of Wettability Gradient for Efficient Fog Collection.

Fog collection plays an important role in alleviating the global water shortage. Despite great progress in creating bionic surfaces to collect fog, water droplets still could adhere to the microscale hydrophilic region and reach the thermodynamic stable state before falling, which delays the transport of water and hinders the continuous fog collection. Inspired by lotus leaves and cactuses, we designed a Janus membrane that functions to both collect fog from the air and transport it to a certain region. The Janus membrane with opposite wettability contains conical microcolumns with a wettability gradient and hydrophilic copper mesh surface. The apexes of conical microcolumns are superhydrophobic and the rest are hydrophobic. The fog droplets were deposited, coalesced, and directionally transported to the bottom of the conical microcolumns. Then, the droplets unidirectionally passed through the membrane and flowed into the water film on the surface of the copper mesh. The asymmetric structural and wettability merits endow the Janus membrane with an improved fog collection of ∼7.05 g/cm2/h. The study is valuable for designing and developing fluid control equipment in fog collection, liquid manipulation, and microfluidics.

A controllable oil-triggered actuator with aligned microchannel design for implementing precise deformation.

Soft actuators with the integration of facile preparation, rapid actuation rate, sophisticated motions, and precise control over deformation for application in complex devices are still highly desirable. Inspired by the aligned structures of moisture responsive pineal scales, an oil-triggered Janus actuator composed of a smooth hydrophobic surface and a superhydrophobic surface with aligned microchannels by simple laser etching was fabricated successfully, which can deform into various desirable shapes and recover to the original shape when triggered by oil and ethanol molecules. The aligned microchannel design causes different oil spread distances in the longitudinal and transverse directions, resulting in orientation-controlled bending and twisting with large-scale displacement. By changing the orientations of the patterned microchannels, one-dimensional folding deformation, twisting, rolling curling and object-inspired architectures can be facilely programmed. The reversible oil-triggered actuator will inspire more attractive applications such as in vivo surgery, biomimetic devices, energy harvesting systems and soft robotics.

Dissolved organic matter (DOM) removal from biotreated coking wastewater by chitosan-modified biochar: Adsorption fractions and mechanisms.

To effectively remove dissolved organic matter (DOM) from actual biotreated coking wastewater (BTCW), a reusable and low-cost chitosan-biochar (CB) was prepared. From the results, CB (52%) exhibited superior removal efficiency compared to that of biochar (12%) and a faster adsorption rate. Analysis of the DOM fractions, molecular weight distribution, fluorescent components, and molecular compositions indicated that chitosan modification made more kinds of DOM components (e.g., hydrophilic substances) have an affinity with biochar. The material characterization and removal characteristics jointly proved that the adsorption efficiency was promoted by the change in pore size distribution and increase in functional groups that provide bonding sites for DOM via hydrogen bonding, acid-base reactions, and electrostatic interactions. Moreover, compared to traditional adsorbent activated carbon, CB exhibited superior removal efficiency and cost-effectiveness. These results demonstrated that CB is a potential alternative adsorbent for advanced DOM treatment of BTCW.

Effect of temperature on the characterization of soluble microbial products in activated sludge system with special emphasis on dissolved organic nitrogen.

Previous research has focused on dissolved organic carbon (DOC) as a surrogate for soluble microbial products (SMPs) and found that temperature has a significant influence on the production of SMP-based DOC (SDOC) during biological processes. Little is known about the SMP-based dissolved organic nitrogen (SDON), although some nitrogenous organic matter has been identified as an important part of SMPs. This study investigated the effect of temperature (8 °C, 15 °C and 25 °C) on the characterization of SMPs in an activated sludge system with special emphasis on SDON. Results showed the positive effect of reduced temperature on SDON production. Fluorescence spectroscopy and ultrahigh-resolution mass spectrometry showed the produced SDON at 8 °C and 15 °C exhibits more lability than at 25 °C. This was also supported by the algal bioassay, indicating the SDON produced at low temperature is highly bioavailable and prone to stimulate algae and microorganisms. In addition, principal component analysis demonstrated that the effect of temperature on the chemical characterization of SDON is different from that of SDOC. Overall, this study highlights the importance of SDON control during biological processes at a low temperature to reduce the potential impact of effluent SMPs on receiving waters or wastewater reuse.

Effect of Solids Retention Time on Effluent Dissolved Organic Nitrogen in the Activated Sludge Process: Studies on Bioavailability, Fluorescent Components, and Molecular Characteristics.

Wastewater-derived dissolved organic nitrogen (DON) should be minimized by municipal wastewater treatment plants (MWWTPs) to reduce its potential impact on receiving waters. Solids retention time (SRT) is a key control parameter for the activated sludge (AS) process; however, knowledge of its impact on effluent DON is limited. This study investigated the effect of SRT on the bioavailability, fluorescent components, and molecular characteristics of effluent DON in the AS process. Four lab-scale AS reactors were operated in parallel at different SRTs (5, 13, 26, and 40 days) for treatment of primary treated wastewater collected from an MWWTP. Results showed the positive effect of prolonged SRT on DON removal. AS reactors during longer SRTs, however, cannot sequester the bioavailable DON (ABDON) and occasionally contribute to greater amounts of ABDON in the effluents. Consequently, effluent DON bioavailability increased with SRT ( R2 = 0.619, p < 0.05, ANOVA). Analysis of effluent DON fluorescent components and molecular characteristics indicated that the high effluent DON bioavailability observed at long SRTs is contributed by the production of microbially derived nitrogenous organics. The results presented herein indicate that operating an AS process with a longer SRT cannot control the DON forms that readily stimulate algal growth.

Polyethylene imine modified hydrochar adsorption for chromium (VI) and nickel (II) removal from aqueous solution.

An adsorbent hydrochar was synthesized from corn cobs and modified with polyethylene imine (PEI). The hydrochars before and after modification were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis. FTIR and XPS revealed that the PEI was grafted onto the hydrochar via ether and imine bonds formed with glutaraldehyde. The maximum adsorption capacities for Cr(VI) (33.663mg/g) and Ni(II) (29.059mg/g) on the modified hydrochars were 365% and 43.7% higher, respectively, than those on the unmodified hydrochar. A pseudo-second-order model described the adsorption of Ni(II) and Cr(VI) on all the adsorbents. The adsorption of Cr(VI) was endothermic, spontaneous, increased disorder, and obeyed the Langmuir model. By contrast, the adsorption of Ni(II) was exothermic, spontaneous, decreased disorder, and obeyed the Freundlich model. XPS confirmed that the adsorption sites and mechanisms for Ni(II) and Cr(VI) on the modified hydrochars were different.

Microwave digestion-assisted HFO/biochar adsorption to recover phosphorus from swine manure.

A sustainable management option for dealing with waste straw is to pyrolyze it to create biochar, which can then be used as a sorbent in pollution treatments, such as the recovery of phosphorus (P) from swine manure. However, the inability to directly capture soluble organic P (OP) and sparingly soluble P and the low selectivity of biochar remain key issues in this process. To overcome these, we investigated a microwave (MW) digestion pretreatment with a HFO/biochar adsorption process. The MW digestion-assisted treatment showed good performance for the solubilization of OP and sparingly soluble P. Optimized conditions (temperature=348K, time=45min, H2O2=3mL/30mL, HCl=0.13%) achieved an inorganic phosphorus (IP) release ratio of 83.98% and a total phosphorus (TP) release ratio of 91.83%. The P adsorption on the HFO/biochar was confirmed to follow pseudo-second-order kinetics, indicating that the P adsorption process was mainly controlled by chemical processes. The Freundlich model offered the best fit to the experimental data. The maximum amount of P adsorbed on HFO/biochar was in the range of 51.71-56.15mg/g. Thermodynamic calculations showed that the P adsorption process was exothermic, spontaneous, and increased the disorder in the system. Saturated adsorbed HFO/biochar was able to continually release P and was most suitable for use in an alkaline soil. The amount of P released from saturated adsorbed HFO/biochar reached 8.16mg/g after five interval extractions. A P mass balance indicated that 8.76% of the TP was available after the solubilization, capture, and recovery processes.