Scientization or parametrization? Which system is more advantageous to environmental conservation in the reform of China's state-owned forest farms?

Government leadership and grassroots participation are the most typical institutional arrangements in natural resource management, a topic which has been the subject of vigorous debate for a long time. Individually, these systems are referred to as scientization and parametrization. This paper takes the reform of China's state-owned forest farms (SSFs) as a pointcut, comparing the effects of the 2011 policy (representing scientization) and the 2015 policy (representing parametrization) on environmental conservation. For the period from 2006 to 2018, China's provinces are analyzed via difference-in-differences (DID) and principal components difference-in-differences (PCDID) empirical strategies. The results show that the 2015 policy increased new afforestation by an average of 0.903 units, but the 2011 policy had no significant impact. The influence path of the 2015 policy was to curb corruption, relieve fiscal stress, and stimulate innovation, playing mechanism effects of 20.49%, 14.17%, and 33.55%, respectively. However, the 2015 policy was not ideal in terms of its goal of incentivizing multi-agent participation in investments in conservation. Investors prefer to attempt afforestation projects with shorter payback periods, especially projects related to open forest land. Overall, this study supports the belief that parametric management is a better approach to natural resource management than scientific management, but the latter approach still has limitations. Therefore, we propose to prioritize the promotion of parametric management on the closed forest lands of SSFs, but there is no need to hastily mobilize grassroots participation in open forest land management projects.

Toxicity of ionic liquids against earthworms (Eisenia fetida)

Ionic liquids (ILs) are widely used in frontier fields because of their highly tunable properties. Although ILs may have adverse effects on organisms, few studies have focused on their effect on earthworm gene expression. Herein we investigated the toxicity mechanism of different ILs towards Eisenia fetida using transcriptomics. Earthworms were exposed to soil containing different concentrations and types of ILs, and behavior, weight, enzymatic activity and transcriptome were analyzed. Earthworms exhibited avoidance behavior towards ILs and growth was inhibited. ILs also affected antioxidant and detoxifying enzymatic activity. These effects were concentration and alkyl chain length-dependent. Analysis of intrasample expression levels and differences in transcriptome expression levels showed good parallelism within groups and large differences between groups. Based on functional classification analysis, we speculate that toxicity mainly occurs through translation and modification of proteins and intracellular transport functions, which affect protein-related binding functions and catalytic activity. KEGG pathway analysis revealed that ILs may damage the digestive system of earthworms, among other possible pathological effects. Transcriptome analysis reveals mechanisms that cannot be observed by conventional toxicity endpoints. This is useful to evaluate the potential environmental adverse effects of the industrial use of ILs.

High reusability and adsorption capacity of acid washed calcium alginate/chitosan composite hydrogel spheres in the removal of norfloxacin

Calcium alginate (CA) hydrogel spheres were widely used as adsorbents to remove organics, but their adsorption capacities and reusability to some antibiotics are unsatisfactory. In this study, calcium alginate/chitosan (CA/CTS) hydrogel spheres were prepared as precursors. Acid-washed CA/CTS (CA/CTS-M) hydrogel spheres (310.6 mg/g) behaved much better adsorption capacity of norfloxacin (NOR) than CA (69.5 mg/g) and CA/CTS (87.7 mg/g) hydrogel spheres. Astonishingly, after being reused for 15 cycles, CA/CTS-M has no loss of NOR adsorption capacity. In the original idea, acid wash was expected to remove the chitosan in CA/CTS hydrogel spheres for obtaining a larger specific surface area. Both scanning electron microscopy and Brunauer-Emmett-Teller test showed that acid wash can remove CTS from CA/CTS hydrogel spheres to increase the specific surface area. However, part of the chitosan remained in CA/CTS-M, having a role to enhance the structural stability of the material, because the acid-washed CA (about 2 mm) has a significantly smaller diameter than CA/CTS-M (about 3 mm). According to the influence of pH and density functional theory calculations, electrostatic attraction is the key driving force of NOR adsorption. Importantly, acid wash led to more negative-charged surface characterized by Zeta potential, which is the main reason of the significantly enhanced adsorption capacity of CA/CTS-M in removal of NOR. In short, CA/CTS-M hydrogel spheres are environment friendly and highly stable adsorbents with high adsorption capacity in the removal of NOR.

Effects of smart city construction on employment: mechanism and evidence from China

Based on the first batch of smart city pilots in China, this paper systematically investigates the impact of smart city construction on urban employment and employment structure, and its influence mechanism and urban heterogeneity are explored using the difference-in-differences (DID) model. The main conclusions are as follows: (1) Smart city construction significantly promotes urban employment, especially employment in the secondary and tertiary industries. (2) Digital technology development and public services are important mechanisms for smart city construction to improve urban employment. (3) There was heterogeneity among Chinese cities, with the employment promotion effect of smart city construction is primarily reflected in cities located in the eastern and central regions, medium cities, large cities, as well as cities with higher levels of financial development, human capital, and informatization. (4) Through different impacts on various sectors, smart city construction promotes the transfer of employment to the service sector and optimizes the urban employment structure. Conclusions enrich the academic community's understanding of the development and construction of smart cities and provide enlightenment and reference for the formulation and promulgation of relevant supporting policies.

Research on the policy effect and mechanism of green finance to reduce environmental pollution: micro evidence from 285 cities in China

Based on panel data from 285 Chinese prefecture-level cities from 2003 to 2020, this paper uses the difference-in-difference (DID) method to investigate the policy effect, mechanism, and heterogeneity of green finance (GF) to reduce environmental pollution. (1) Green finance has significant effect on reducing environmental pollution. The parallel trend test demonstrates that DID test results are valid. (2) Following a battery of robustness tests including instrumental variable, propensity score matching (PSM), variable substitution, and changing time-bandwidth, the conclusions are still valid. (3) Mechanism analysis reveals that green finance can reduce environmental pollution by increasing energy efficiency, adjusting industrial structure, and transforming green consumption. (4) Heterogeneity analysis proves that green finance has a substantial impact on reducing the environmental pollution in eastern and western cities, but not in central China. (5) In the "two-control zone" and "low-carbon pilot cities," the results of applying green finance policies are better, and a policy superposition effect exists. To be able to promote environmental pollution control, and green and sustainable development, this paper provides useful enlightenment for environmental pollution control for China and other similar countries.

How does agricultural industrial structure upgrading affect agricultural carbon emissions? Threshold effects analysis for China

China continues to emphasize the importance of reducing agricultural carbon emissions and promoting the upgrading of its agricultural industry structure. However, the relationship between the two is rarely examined. This study aims to investigate the impact of upgrading the agricultural industry structure on agricultural carbon emissions. A two-stage instrumental technique and a threshold regression model are used in this study's analysis. The results indicate that agricultural industrial structure upgrading reduces agricultural carbon emissions by a statistically significant amount above the threshold of 0.378. The examination of the underlying mechanism shows agricultural energy efficiency and off-farm work as mediators of the nonlinear relationship between agricultural industrial structure upgrading and agricultural carbon emissions. Only when the agricultural energy efficiency and off-farm work thresholds are surpassed can improving the structure of the agricultural industry minimize agricultural carbon emissions. Analysis of heterogeneity indicates that the threshold for lowering agricultural carbon emissions is greater in northern China, but the potential for reduction is greater.

The impact of digital transformation on innovation performance - The mediating role of innovation factors

Existing digital transformation research has focused on economic and environmental performance, which few studies directly explored the relationship between digital transformation and innovation. Based on the innovation factor perspective, we explored the relationship between digital transformation and innovation by using firm data between 2009 and 2019. The findings are as follows: (1) The corporate digital transformation was measured through based on textual analysis methods and it was found that digital transformation can promote corporate innovation. (2) Knowledge flow, technical personnel, R&D investment, and innovation awareness are important mediating paths. (3) In the innovation quantity dimension, the mediating role of innovation awareness is greater. And in the innovation quality dimension, the mediating role of technicians is greater. (4) Digital transformation has a greater impact on innovation of non-SOEs, non-high-tech enterprises and non-heavily polluting enterprises, alleviating the gap between different types of firms. The results of this paper alleviate the concerns of digital transformation in developing countries such as China and provide experiences and evidence for them to promote Industry 4.0 and sustainable innovation.

How to achieve sustainable development: From the perspective of science and technology financial policy in China

To solve coordination between economic development and pollutant emissions, it is necessary to face the innovation problem of energy saving and emission reduction. Promoting the effective integration of tech and the financial system is an effective way to solve this problem. According to panel data for prefecture-level cities in China, this paper is based on the pilot policy of combining science and technology with finance implemented in 2011 as a quasi-natural experiment and uses the difference-in-differences (DID) method to evaluate the impact of Science and Technology Financial Policies (STFP) on the air pollutant emission, meanwhile, considering the spatial overflow effect of policy implementation. The research results show that: (1) The STFP has certain inhibitions on pollutant emissions, and this finding holds after a series of robustness tests. (2) The policy has different effects on cities that have different scale, different regions, and different government efficiency. (3) From the results of mechanism analysis, the policy mainly enhances regional pollutant emission reduction capacity through ways such as increasing regional green total factor productivity, enhancing regional science and technology levels, and promoting regional industrial structure optimization. (4) The policy shows a negative spatial spillover effect in reducing pollutant emissions.

Rational construction and understanding the effect of metal cation substitution of three novel ternary Zn-Co-Ni-LDHs from 2D to 3D and its enhanced adsorption properties for MO

The layered double hydroxides (LDHs) have attracted attention in the water treatment field. In this paper, three novel ternary Zn-Co-Ni-LDH adsorbents were prepared successfully through rational construction from 2D to 3D using triethanolamine (TEA) as an alkali source and a structural controlling reagent by hydrothermal technique. Samples were characterized by the SEM, XRD, XPS, FTIR, BET, solid-state UV/vis spectra, and TG. Three Zn-Co-Ni-LDHs exhibited higher crystallinity and surface area which were beneficial to the adsorption for methyl orange (MO). The maximum adsorption capacity of three Zn-Co-Ni-LDH adsorbents can even reach as high as 1871.65 mg·g^-1, 1799.56 mg·g^-1, and 1646.44 mg·g^-1 for MO, respectively, which surpass those of most previously reported LDH-based adsorbents. The pseudo-second-order kinetic equation fitted the kinetic data of adsorption, while the equilibrium adsorption isotherm data followed the Langmuir model. The adsorption mechanism, electrochemical, and the antibacterial properties of three Zn-Co-Ni-LDHs were also discussed. This results not only demonstrates that three Zn-Co-Ni-LDHs are practical interest as an efficient adsorbent for the removal of MO from dye waste water, but also provides a strategy for the rational design through three ternary Zn-Co-Ni-LDHs from 2D to 3D.

Dynamic monitoring of bacteriostatic process by SERS analysis based on a simple but effective detection strategy

Investigating antibacterial process at a molecular level is helpful to fully understand the mechanism of bacteriostasis and develop new antimicrobial agents. Herein, a simple but effective sensor strategy of antibacterial nanocomposite combined with surface-enhanced Raman scattering (SERS) substrate was applied for the robust detection of bacteriostatic process. The synergistic SERS effect of nanocomposite and Ag nanoparticles (NPs) substrate was confirmed by finite difference time domain (FDTD) solutions. A curcumin liposome@Au NPs nanocomposite was designed and prepared as a kind of bacteriostatic agent and SERS material as well. By means of electrostatic attraction between the nanocomposite and bacteria (methicillin resistant staphylococcus aureus, MRSA), specific detection of MRSA and monitoring of the molecular structure changes after bacteriostaticeffect were realized by SERS. Important intermediates produced in the bacteriostatic process were also measured at the same time. The relationship between the relative peak intensities and the structure of MRSA were thus established. The results were verified by high performance liquid chromatography-mass spectrometry (HPLC-MS), reactive oxygen species (ROS) kit, and flow cytometry. The detection strategy we proposed could not only be used for real-time detection of bacteriostatic processes with a high efficiency, but also a powerful tool for analyzing the mechanism in biochemical processes.

How can urban administrative boundary expansion affect air pollution? Mechanism analysis and empirical test

As a momentous policy tool for spatial management, urban administrative boundary expansion (UABE) significantly impacts resource reorganization and development modes. However, the environmental effects of UABE are easily ignored. Whether UABE can also impove the environmental quality in addition to its economic effects remains to be answered. To fill this gap, we took the city-county merger policy (CCMP) in China as quasi-experimental evidence and empirically investigated the impacts of CCMP on air pollution based on the difference-in-difference method. The impact mechanisms were also analyzed from a whole-process perspective. The results demonstrate that, apart from expanding the urban scale, UABE can improve urban air quality as well. Further analysis shows that the positive effect is mainly realized by source control and process management, rather than end-of-pipe treatment. Besides, the impacts of UABE on air pollution exhibit obvious spatial heterogeneous characteristics. We also reported that the environmental effects of UABE are largely dependent on governmental control, rather than market factors. According to the results above, flexible administrative boundary adjustment, strict government regulations, and effective market systems are required to realize the dual goals of environmental improvement and space optimization.

Comprehensive evaluation of cobalt incorporated cryptomelane-type manganese oxide molecular sieve as an efficient adsorbent for enhanced removal of europium from wastewater systems

Extraction of radionuclide contaminants from wastewater systems has recently drawn widespread attention, and then developing a novel and green extracting technology has also become an enormous challenge. Herein, a facile hydrothermal method was employed to fabricate cobalt-incorporated cryptomelane-type manganese oxide molecular sieve (Co-OMS-2) for extraction Eu(III) from wastewater under diverse experimental conditions. All kinds of characterized techniques, such as SEM, TEM, XRD, FTIR, BET, EDS and XPS had verified the qualified synthesis process and splendid structural features of the Co-OMS-2. The maximum adsorption capacity of Co-OMS-2 was 7.62 × 10^-4 mol/g for Eu(III) at 298 K, which was superior than primarily traditional materials reported previous literatures. The high adsorption capacity of Eu(III) onto Co-OMS-2 was primarily attributed to high specific surface area and abundant surface functional groups, and the interactions were mainly contributed to strong surface complexation and electrostatic attraction. Under the condition of low pH, the outer-sphere surface complexation and cation exchange were primary mechanisms to Eu(III) adsorption onto Co-OMS-2 composites, while inner-sphere surface complexation was mainly assigned to Eu(III) adsorption onto Co-OMS-2 under the high pH sections. The Co-OMS-2 composite achieved equilibrium in a relatively short time, and this excellent performance was conducive to the treatment of Eu(III) under the extreme emergency conditions. In view of the extraordinary adsorption capacity and recycled reusability, the Co-OMS-2 composites can be as prospective adsorbents adopted for the extraction of Eu(III) in real wastewater management.

The impact of smart city pilots on corporate total factor productivity

The existing literature on smart city pilots mainly focuses on the city level and rarely addresses the firm level. This paper assesses the impact of smart city pilot policy (SCP) on firms' total factor productivity (TFP) and explores the impact of SCP under different heterogeneities as well as the mechanisms of action of the SCP. The LP approach is used in this paper to measure firms' TFP, and the impact of SCP is analyzed by the DID model with firms' panel data from 2009 to 2019 as research objects. First, it was found that the SCP can significantly increase the TFP of firms (0.041). Second, through heterogeneity analysis, we found that SCP can strengthen the monopoly position of monopolistic firms and state-owned enterprises. Moreover, the SCP can also alleviate the development imbalance of TFP between firms in coastal and non-coastal areas. In addition, SCP can significantly improve TFP of heavy polluting enterprises. Finally, we find that the important ways for SCP to improve firms' TFP is increasing investment in technological innovation, talent agglomeration, attracting financing, improving resource allocation efficiency, and digital transformation. The study provides unique insights for policy makers and business managers in China and other emerging countries to enhance TFP and achieve corporate sustainable development.

Highly sensitive detection of H2S gas at low temperature based on ZnCo2O4 microtube sensors

It is extremely necessary to detect Hydrogen sulfide (H₂S) due to the hazardous nature. Thus, it is required to design a material which can detect H₂S gas at low temperature. In this work, ZnCo₂O₄ microtubes are prepared by using absorbent cotton as template, combining immersion method in metal salt solution (Zn:Co=1:2) with calcination treatment in air. The influence of calcination temperature on the particle size and sensing property was also discussed. The diameter of particles on the ZnCo₂O₄ microtubes increases with increasing calcination temperature. The hollow microtubes of ZnCo₂O₄ materials calcined at 600 °C (ZCO-600) exhibit superb sensing performance to H₂S at 90 °C with the lowest detection limit of 50 ppb. The optimum operating temperature (90 °C) was lower than the other reported ZnCo₂O₄ sensors. ZCO-600 sensor also shows excellent selectivity, repeatability, stability, humidity resistance and the good linear relationship in ppb and ppm level H₂S. In addition, the feasible sensing mechanism of ZCO-600 to H₂S is explored on the basis of XPS analysis. Thus, ZnCo₂O₄ as a sensing material possesses widespread application prospects for the detection of trace H₂S gas.

Two-dimensional activated carbon nanosheets for rapid removal of tetracycline via strong π-π electron donor receptor interactions

Two-dimensional carbonaceous materials have sparked extensive attention in organic pollutants adsorption due to their unique structure to facilitate the formation of the physical or chemical bonding. Herein, natural two-dimensional porous activated carbon nanosheets with ultra-high specific surface area (2276.44 m² g^-1) are prepared by alkaline immersion-assisted circulating calcination techniques from corn straw piths. The prepared nanosheets exhibit rapid tetracycline adsorption capacity (633 mg g^-1 within 5 min) and high equilibrium adsorption capacity of 804.5 mg g^-1. Significantly, the nanosheets can adapt to a wide range of pH (at least between pH = 3-10) and are almost unaffected by coexisting ions. Mechanism studies and theoretical calculations demonstrate that the rapid and high-efficient adsorption of tetracycline mainly depends on the π-π electron donor receptor interactions. In addition, hydrogen bonding and pore filling was also responsible for tetracycline adsorption. This work provides important guidance for the development of the biobased high-performance adsorbents from agricultural waste.

Environmental regulation, market demand, and green innovation: spatial perspective evidence from China

This paper used a dynamic spatial panel model to empirically analyze the effects of environmental regulation, market demand, and the associated spatial spillovers on regional green innovation in China, from which the following was found. (1) The environmental regulations had a positive "U-shaped" effect on local green innovation and a positive neighborhood spillover effect, and market demand had a significant positive effect on local green innovation and a "ripple effect." (2) The mechanism analysis found that the environmental regulations tended to inhibit regional green innovation input through a "cost compliance" effect, and market demand had a stronger incentive effect on innovation input than the environmental regulations, thus promoting the improvement of green innovation level. (3) The environmental regulation and market demand effects on green innovation had obvious spatial and temporal heterogeneity. The results of this study could help to promote regional green innovation by formulating reasonable environmental policies and stimulating the vitality of green technology market.

Investigation on the application of by-product steam in iron ore sintering: performance and function mechanism

The combustion-supporting effect of steam to coke breeze in sintering has the potential to improve sinter quality and reduce pollutants emissions. The results show that increasing the by-product steam injection concentration (0.32-0.47vol%) and prolonging the injection time (5 min) within a proper range (10-15 min) can improve sinter quality. 2.13kgce/t_-sinter of the fuel consumption was decreased by reducing coke breeze usage from 5.60 to 5.45% under the recommended parameters, with 15.16% decrease of CO in sintering waste gas. By comparing experimental data with thermodynamic calculations, although the reaction between CO and steam can reduce CO emission and generate H₂, steam tends to react with coke breeze to generate H₂ and CO (react at 674℃), and OH radical produced by H₂ which can reduce the activation energy of CO oxidation reaction is the key to reducing pollutant emissions. The potential economic benefit of steam injection technology was calculated based on a 360m² sintering machine (the annual sinter output is 3.2million tons), excluding the equipment modification and steam injection cost of $300,000; a profit of $737491.2 per year or 0.23 dollars per ton sinter can be achieved. Therefore, low-carbon and cleaner iron ore sintering production can be realized through applying by-product steam.

Activation of persulfate by a water falling film DBD process for the enhancement of enrofloxacin degradation

A synergetic system of water falling film dielectric barrier discharge (DBD) plasma and persulfate (PS) was established and applied to enhance the enrofloxacin (EFA) degradation in this study. The simultaneous existence of electrons, reactive species, heat and UV-visible light in the DBD plasma system were utilized together to activate the PS to form SO₄^-· and other reactive oxygen species (ROS), and then worked in synergy with the DBD plasma to oxidize the EFA. The obtained results verified that there was a significant increase in the degradation percentages of EFA (20 mg L^-1) in the DBD/PS system, and the trend was more obvious under the condition of larger discharge power input. When 0.8 mM PS was added into the DBD system with 0.8 kW discharge power, the degradation percentage of EFA could reach 99.35% after 60 min treatment, the corresponding synergetic factor (SF) was 7.94. Analysis of the O₃ and the H₂O₂ concentrations in the DBD plasma system before and after the PS addition explained the activation of the PS by the HO·. The quenching experiments on reactive species suggested that SO4^-·, HO·, and ¹O₂ were all important reactive species for EFA degradation. The intermediates formed by the EFA degradation were detected and the degradation pathways were speculated. Results of toxicity analysis illustrated that the toxicity of the initial EFA solution decreased after degradation in the synergetic system of DBD/PS.

Facile synthesis of CoOOH@MXene to activate peroxymonosulfate for efficient degradation of sulfamethoxazole: performance and mechanism investigation

Using MXene as substrate, CoOOH@MXene with different mass content of CoOOH were prepared and used to active peroxymonosulfate (PMS) for the sulfamethoxazole (SMX) degradation. The sample characterizations demonstrated the successful preparation of CoOOH@MXene. CoOOH@MXene possessed much higher BET surface area (183.82 m²/g) than CoOOH (85.36 m²/g) and MXene (6.89 m²/g) due to the good dispersibility of CoOOH particles on MXene. Due to its large surface area, 1.3CoOOH@MXene displayed the best catalytic performance for the degradation of SMX. With 0.2 g/L of 1.3CoOOH@MXene and 0.5 mM of PMS, 20 μM of SMX was completely eliminated in 10 min. The degradation followed pseudo-first-order kinetic model well, with rate constants of 0.33 min^-1 for 1.3CoOOH@MXene and 0.054 min^-1 for CoOOH. Influencing factors of initial pH, catalyst dosage, PMS concentration, SMX concentration, and co-existing anions on SMX degradation were assessed systematically. Recycling tests verified the excellent reusability and stability of the catalyst. Quenching experiments and electron paramagnetic resonance analysis substantiated that ¹O₂ played a leading role. Moreover, the intermediates were identified, and degradation pathways and activation mechanism of CoOOH@MXene for PMS were proposed. This work may highlight the application of MXene with transition metals in PMS activation.

Does air pollution collaborative governance promote green technology innovation? Evidence from China

With the data of Chinese A-share-listed companies from 2004 to 2017, this paper builds a difference-in-differences model to investigate the impact of air pollution collaborative governance on green technology innovation. The main results show that air pollution collaborative governance promotes green technology innovation, and a series of robustness tests also verify this conclusion. Patent heterogeneity analysis suggests that air pollution collaborative governance increases the number of green utility model patents, but has no obvious impact on green invention patents. In terms of enterprise heterogeneity, air pollution collaborative governance can effectively stimulate the non-heavy-polluting enterprises to innovate green technology, but the incentive effect on heavy-polluting enterprises is not evident. Moreover, by constructing a mediating effect model and a moderating effect model, mechanism analysis reveals that R&D investment plays a positive mediating role in the impact of air pollution collaborative governance on green technology innovation, and the increase of government subsidy also enhances the promotion effect of air pollution collaborative governance on green technology innovation.

Oxidoreduction potential controlling for increasing the fermentability of enzymatically hydrolyzed steam-exploded corn stover for butanol production

Background

Lignocellulosic biomass is recognized as an effective potential substrate for biobutanol production. Though many pretreatment and detoxification methods have been set up, the fermentability of detoxicated lignocellulosic substrate is still far lower than that of starchy feedstocks. On the other hand, the number of recent efforts on rational metabolic engineering approaches to increase butanol production in Clostridium strains is also quite limited, demonstrating the physiological complexity of solventogenic clostridia. In fact, the strain performance is greatly impacted by process control. developing efficient process control strategies could be a feasible solution to this problem.

Results

In this study, oxidoreduction potential (ORP) controlling was applied to increase the fermentability of enzymatically hydrolyzed steam-exploded corn stover (SECS) for butanol production. When ORP of detoxicated SECS was controlled at − 350 mV, the period of fermentation was shortened by 6 h with an increase of 27.5% in the total solvent (to 18.1 g/L) and 34.2% in butanol (to 10.2 g/L) respectively. Silico modeling revealed that the fluxes of NADPH, NADH and ATP strongly differed between the different scenarios. Quantitative analysis showed that intracellular concentrations of ATP, NADPH/NADP⁺, and NADH/NAD⁺ were increased by 25.1%, 81.8%, and 62.5%. ORP controlling also resulted in a 2.1-fold increase in butyraldehyde dehydrogenase, a 1.2-fold increase in butanol dehydrogenase and 29% increase in the cell integrity.

Conclusion

ORP control strategy effectively changed the intracellular metabolic spectrum and significantly improved Clostridium cell growth and butanol production. The working mechanism can be summarized into three aspects: First, Glycolysis and TCA circulation pathways were strengthened through key nodes such as pyruvate carboxylase [EC: 6.4.1.1], which provided sufficient NADH and NADPH for the cell. Second, sufficient ATP was provided to avoid “acid crash”. Third, the key enzymes activities regulating butanol biosynthesis and cell membrane integrity were improved.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01824-2.

Rare pattern of Maisonneuve fracture: A case report

BACKGROUND

Maisonneuve fracture is a special type of ankle fracture that consists of proximal fibular fracture, a lesion of the inferior tibiofibular syndesmotic complex (interosseous ligament, anterior inferior tibiofibular ligament and posterior inferior tibiofibular ligament), and injury of the medial structure of the ankle (deltoid ligament tear or medial malleolar fracture). The accepted mechanism of Maisonneuve fracture is pronation external rotation according to the Lauge-Hansen classification. In this paper, we report a rare pattern of Maisonneuve fracture, which has the characteristics of both pronation external rotation ankle fracture and supination adduction ankle fracture.

CASE SUMMARY

A 31-year-old female patient accidentally sprained her right ankle while walking 5 d before hospitalization in our hospital. The patient was initially missed in other hospitals and later rediagnosed in our outpatient department. Full-length radiographs of the lower leg revealed proximal fibula fracture, inferior tibiofibular joint separation, and medial malleolar fracture involving the posterior malleolus, which was also revealed on computed tomography scans. Magnetic resonance imaging revealed rupture of the anterior inferior tibiofibular ligament and anterior talofibular ligament. We diagnosed a rare pattern of Maisonneuve fracture with proximal fibular fracture, inferior tibiofibular joint separation, medial malleolar fracture and ruptures of the anterior inferior tibiofibular ligament and anterior talofibular ligament. The patient underwent open reduction and internal fixation in our hospital. A 6-mo postoperative follow-up confirmed a good clinical outcome.

CONCLUSION

To our knowledge, this rare pattern of Maisonneuve fracture has not been previously described. The possible mechanism of injury is supination adduction combined with pronation external rotation. Careful analysis of the injury mechanism of Maisonneuve fracture is of great clinical significance and can better guide clinical treatment.

Pilot-scale microsand-ballasted flocculation of wastewater: turbidity removal, parameters optimization, and mechanism analysis

The flocs formed during microsand-ballasted flocculation (MBF) have attracted much attention. However, few studies have reported on comprehensive process parameters of MBF and its mechanism is still not well understood. Jar test and pilot-scale continuous experiments were here conducted on two kinds of simulated wastewater, labeled S1 (21.6-25.9 NTU) and S2 (96-105 NTU). Results revealed the hydraulic retention time ratio in the coagulation cell, injection and maturation cell, lamella settler of pilot-scale MBF equipment was 1:3:7.3. The optimum poly aluminum chloride doses for samples S1 and S2 were 0.875 g/L and 1.0 g/L. Besides, the optimum size of microsand was 49-106 μm and the optimum dose was 1.0 g/L. Under aforementioned conditions, the effluent turbidity of S1 was below 0.47 NTU, even lower than the Chinese drinking water standard; that of S2 was below 1.7 NTU, meeting the Chinese recycled water standard. Turbidity removal ranged from 98.0 to 98.8% for S1 and 98.5 to 99.5% for S2 when microsand was added. Therefore, microsand addition enhances MBF performance, where microsand serves as an initial core particle. Some microsand core particles bond together to form a dense core structure of micro-flocs by the adsorption bridging of inorganic polymeric flocculant. Moreover, the size of the largest micro-flocs may be controllable as long as the effective energy dissipation coefficient is adjusted appropriately through specific stirring speeds. This work provides comprehensive pilot-scale process parameters for using MBF to effectively treat wastewater and offers a clearer explanation of the formation mechanism of microsand-ballasted flocs.

A novel strategy for rapid development of a self-sustaining symbiotic algal-bacterial granular sludge: Applying algal-mycelial pellets as nuclei

Algal-bacterial granular sludge (ABGS) is a promising technology for wastewater treatment, benefiting from the synergetic interactions between algae and bacteria. However, the rapid start-up of the ABGS system is not trivial. Herein, a novel strategy was proposed by applying the algal-mycelial pellets (AMPs) as the primary nuclei for accelerating the development of a self-sustaining symbiotic ABGS system. The results indicated that by using this strategy complete granulation was shortened to 12 days, much shorter than the control system without AMPs dosage (28 days). The ABGS had a large particle diameter (3.3 mm), compact granular structure (1.0253 g/mL), and excellent settleability (SVI30 of 53.2 mL/g). Moreover, 98.6% of COD, 80.8% of TN and 80.0% of PO43--P were removed by the ABGS. The nuclei of targeted algae (Chlorella) and filamentous fungi (Aspergillus niger), the enhanced production of extracellular polymeric substances (especially proteins) and the enrichment of functional bacteria (such as Neomegalonema and Flavobacterium) facilitated the granules development. The low surface free energy (-69.56 mJ/m2) and energy barrier (89.93 KT) were the inherent mechanisms for the strong surface hydrophobicity, the easy bacterial adhesion, and the short granulation period. This study provides an economically feasible approach to accelerate ABGS granulation and sustain system stability.

Can "new infrastructure" reverse the "growth with pollution" profit growth pattern? An empirical analysis based on listed companies in China

With the increasing severity of environmental regulations, Chinese enterprises are gradually transforming from the profit growth pattern of "growth with pollution" to green development. However, this paper finds that this transformation is not complete. While catering to the national environmental protection governance requirements, some enterprises still persist the profit growth pattern of "growth with pollution." How to solve this problem? By attracting government subsidies, reducing tax burdens, and increasing the proportion of technical personnel employed, we theoretically and empirically demonstrate that the positive effect of "new infrastructure" in accelerating enterprises' transformation away from the profit growth pattern of "growth with pollution" to sustainable development. In the heterogeneity analysis section, we found that in enterprises with higher political correlation, more technical personnel, and lower labor cost, the "new infrastructure" has a stronger restraining effect on the "growth with pollution" pattern.