Mussel-inspired tissue adhesive composite hydrogel with photothermal and antioxidant properties prepared from pectin for burn wound healing.

Biodegradable self-healing hydrogels with antibacterial property attracted growing attentions in biomedication as wound dressings since they can prevent bacterial infection and promote wound healing process. In this research, a biodegradable self-healing hydrogel with ROS scavenging performance and enhanced tissue adhesion was fabricated from dopamine grafted oxidized pectin (OPD) and naphthoate hydrazide terminated PEO (PEO NH). At the same time, Fe3+ ions were incorporated to endow the hydrogel with near-infrared (NIR) triggered photothermal property to obtain antibacterial activity. The composite hydrogel showed good hemostasis performance based on mussel inspired tissue adhesion with biocompatibility well preserved. As expected, the composition of FeCl3 improved conductivity and endowed photothermal property to the hydrogel. The in vivo wound repairing experiment revealed the 808 nm NIR light triggered photothermal behavior of the hydrogel reduced the inflammation response and promoted wound repairing rate. As a result, this composite FeCl3/hydrogel shows great potential to be an excellent wound dressing for the treatment of infection prong wounds with NIR triggers.

Bioinspired poly(aspartic acid) based hydrogel with ROS scavenging ability as mEGF carrier for wound repairing applications.

Poly(amino acid) based self-healing hydrogels have important application in biomedications. In this research, the catechol pendant groups were imported to poly(aspartic acid) based self-healing hydrogel to improved skin adhesion and ROS scavenging performance. The poly(succinimide) (PSI) was reacted with 3,4-dihydroxyphenylalanine (DA) and then hydraziolyzed to import catechol group and hydrazide group respectively, which are responsible for mussel inspired tissue adhesion and dynamic coupling reactivity. The dopamine modified poly(aspartic hydrazide) (PDAH) was reacted with PEO90 dialdehyde (PEO90 DA) to prepare hydrogels, and the resultant hydrogel showed good biocompatibility both in vitro and in vivo. The skin adhesion strength of the mussel inspired hydrogel increased notably with enhanced radical scavenging efficiency fit for in vivo wound repairing applications. The PDAH/PEO90 DA hydrogel also showed sustained albumin release profile and the in vivo wound repairing experiment proved the mouse Epidermal Growth Factor (mEGF) loaded hydrogel as wound dressing material accelerated the wound repairing rate.

[Retention Effect of Heavy Metals in Rivers of a Typical Mountainous City by Cascade Weirs: A Case Study of Liangtan River in Chongqing].

Contaminants such as heavy metals in rivers are partially retained in the sediments at the bottom as a result of the altered water regime within the cascade weirs. The associated heavy metals in the sediments can affect surface water quality and ecology for a long period. In May 2020, sediments were collected in a typical mountainous river (Liangtan River) with cascade weirs in the main urban area of Chongqing. The accumulation of sediments in each river section, the content of heavy metals, and other basic physicochemical indicators in the samples were monitored. The results showed that the average ω(As), ω(Cd), ω(Cu), ω(Hg), ω(Ni), and ω(Pb) in the sediments of the main stream of Liangtan River were (4.66±4.78), (0.361±0.256), (32.30±14.38), (0.069±0.039), (33.47±15.37), and (26.34±11.52) mg·kg-1, respectively. A large coefficient of spatial variation regarding the content of heavy metals in the sediments across the sampling sites was observed owing to the uneven spatial distribution of pollution sources and the destruction of river connectivity by cascade weirs. The modified geoaccumulation index (Im) showed that Cd was the most polluted heavy metal element in the sediments. Of the monitored river sections, 12.50% approached or were at moderate pollution levels, and these sections were mainly found in the upstream and downstream reaches of Liangtan River with relatively concentrated construction lands. The potential ecological risk assessment index method (RI) and the sediment quality guideline method (SQGs) showed that, in addition to Cd and Hg with a high pollution level and strong toxicity, Ni in the sediments also posed a potential threat to the ecological safety of surface water due to its high background content in the watershed. The total amounts of As, Cd, Cu, Hg, Ni, and Pb retained in the sediments by cascade weirs were estimated to be 446.10, 47.28, 4997.80, 10.81, 5135.68, and 4048.16 kg, respectively, in which Cd, Ni, and Pb were identified to be the major threats to the ecological safety of surface water over a long period. The upper reaches prior to the weirs with the most retained heavy metals and the easier formation of an anaerobic environment are suggested to be the key areas for investigation of the endogenous release of heavy metals. Source apportionment of heavy metals in river sediments through the combination of principal component analysis and cluster analysis revealed that Cd, Cu, and Pb mainly originated from residential/industrial point source pollution. Hg mainly originated from agricultural non-point source pollution, whereas As and Ni mainly originated from natural soil erosion.

[Spatial Distribution and Influential Factors of Nutrients in Rivers of a Typical Mountainous City: A Case Study of the Qingshuixi River in Chongqing].

Surface water pollution seriously restricts the development of the city and results in the citizens yearning for a better life. Mountainous cities have their own characteristics in surface water environment and pollution compared with those of plain cities due to their unique topography. In August and October 2019, surface water and sediments were collected in a typical river (Qingshuixi River) in the main urban area of Chongqing. These samples were analyzed for nutrients such as carbon, nitrogen, and phosphorus as well as other basic physicochemical indicators. The results showed that the surface water of the Qingshuixi River was inferior to Category V at present, and it was also at a serious pollution level according to the comprehensive pollution index evaluation system. Among all the water quality indices, NH4+ and TP showed the most serious pollution. The tributaries of the Qingshuixi River exhibited higher surface water quality than that of the main stream, and the water quality during the rainfall season was better than that during the non-rainy season. Pollution sources, tailwater/tributary inflow, and river self-purification capacity determined the spatial distribution of nutrients in the surface water of the mainstream of the Qingshuixi River. Point sources such as the direct discharge of source sewage and pollution overflow in the middle and lower reaches were the most important sources of surface water pollution in the mainstream of the Qingshuixi River. Non-point source pollution had a limited impact on water quality. The "sink" or "source" role transformation of river sediments would occur under different water volume conditions in the river, reflecting the complexity of endogenous pollution. Surface water quality of the main stream showed a gradual improvement tendency along the downstream due to the dilution of the tail water/tributary inflow and the increased self-purification capability of the surface water in the mountainous rivers due to the increased DO content. To summarize, this study suggests that the water environment of the Qingshuixi River should be improved in comprehensive ways, which might be reducing the input of point source pollution by the deployment of the municipal pipe network in key areas, upgrading the sewage treatment plants to decrease pollutant concentrations or fluxes or channel dredging at the reaches with low DO content, etc.

How to Establish a Bioregenerative Life Support System for Long-Term Crewed Missions to the Moon or Mars.

To conduct crewed simulation experiments of bioregenerative life support systems on the ground is a critical step for human life support in deep-space exploration. An artificial closed ecosystem named Lunar Palace 1 was built through integrating efficient higher plant cultivation, animal protein production, urine nitrogen recycling, and bioconversion of solid waste. Subsequently, a 105-day, multicrew, closed integrative bioregenerative life support systems experiment in Lunar Palace 1 was carried out from February through May 2014. The results show that environmental conditions as well as the gas balance between O2 and CO2 in the system were well maintained during the 105-day experiment. A total of 21 plant species in this system kept a harmonious coexistent relationship, and 20.5% nitrogen recovery from urine, 41% solid waste degradation, and a small amount of insect in situ production were achieved. During the 105-day experiment, oxygen and water were recycled, and 55% of the food was regenerated. Key Words: Bioregenerative life support systems (BLSS)-Space agriculture-Space life support-Waste recycle-Water recycle. Astrobiology 16, 925-936.

Microbial fuel cell as power supply for implantable medical devices: a novel configuration design for simulating colonic environment.

This study focused on providing power for implantable medical devices (IMDs) using a microbial fuel cell (MFC) implanted in human transverse colon. Considering the condition of colonic environment, a continuous-flow single-chamber MFC without membrane was set up. The performance of the MFC was investigated. The power output of 1.6 mW under the steady state was not rich enough for some high energy-consuming IMDs. Moreover, the parameters of the simulated colonic environment, such as pH and ORP value, varied along with the time. Hence, a new MFC configuration was developed. In this novel model, pH transducers were placed in cathodic and anodic areas, so as to regulate the reactor operation timely via external intervention. And two ORP transducers were inserted next to the pH transducers, for monitoring and adjusting the MFC operation efficiently. Besides, colonic haustra were designed in order to increase the difference between cathodic and anodic areas.

Increased power density from a spiral wound microbial fuel cell.

Using Microbial fuel cell (MFC) to convert organic and inorganic matter into electricity is of great interest for powering portable devices, which is now still limited by the output of MFC. In this study, a spiral wound MFC (SWMFC) with relatively large volume normalized surface area of separator (4.2 cm(2)/ml) was fabricated to enhance power generation. Compared with double-membrane MFC (DMMFC) and conventional double chamber MFC (DCMFC), the power density of SWMFC increased by 42% and 99% resulted from its lower internal resistance. Besides larger separator area, the better performance of SWMFC benefited from its structure sandwiching the cathodes between two separators. This point was proved again by a comparison of another DCMFC and a triple chamber MFC (TCMFC) as well as a simulation using finite element method. Moreover, the feature of SWMFC was more convenient and compact to scale up. Therefore, SWMFC provides a promising configuration for high power output as a portable power source.

Stabilization of a premixed CH4/O2/N2 flame using femtosecond laser-induced plasma.

The influence of femtosecond laser-induced plasma (FLIP) on the stability of a premixed CH(4)/O(2)/N(2) flame is investigated at atmospheric pressure. The laser energy, laser repetition rate, the equivalence ratios, and the volume percentage of oxygen in O(2)/N(2) blends are varied. Our findings indicate that the flame blow-off velocity is a function of these parameters. It has been experimentally found that the flame blow-off velocity increases by a factor of two with FLIP than without FLIP. A high-repetition-rate and a great energy laser-induced plasma flameholding, as a non-intrusive optical flameholding, may be a feasible alternative for any combustor.

Continuous flowing membraneless microbial fuel cells with separated electrode chambers.

Microbial fuel cell (MFC) is an emerging technology in the energy and environment field. Its application is limited due to its high cost caused by the utilization of membranes and noble metal catalysts. In this paper, a membraneless MFC, with separated electrode chambers, was designed. The two separated chambers are connected via a channel and the continuous electrolyte flow from anode to cathode drives proton transfer. The proton mass transfer coefficiency in this MFC is 0.9086 cm/s, which is higher than reported MFCs with membranes, such as J-cloth and glass fiber. The maximum output voltage is 160.7 mV, with 1000 Ω resistor. Its peak power density is 24.33 mW/m³. SCOD removal efficiency can reach 90.45% via this MFC. If the connection between the two electrode chambers is blocked, the performance of MFC will decrease severely. All the above results prove the feasibility and advantages of this special MFC model.

Effects of the Pt loading side and cathode-biofilm on the performance of a membrane-less and single-chamber microbial fuel cell.

In order to analyze the effect of cathode's Pt loading side on the performance of single-chamber microbial fuel cells (MFCs), power generation of a bamboo charcoal membrane-less air-cathode MFC was examined. The maximum power outputs obtained were 0.144 and 1.16 mW, while the maximum voltage outputs were 0.400 and 0.500 V (external resistance was 500 Omega), respectively, when the Pt loading side facing to the air and to the anode chamber solution; after a long time of operation with the side of cathode loaded Pt facing to anode chamber solution, a biofilm was developed on the inner side of cathode. With the formation of this biofilm, the power outputs of MFC increased first, and then decreased to 0.8 mW; oxidation-reduction potentials (ORP) dropped first, and then achieved the level of stability. Coulombic efficiency (CE) increased at a certain extent. In addition, the impact of cathode-biofilm on the loss of water in anode chamber solution was determined.