Mucor circinelloides has been commonly used as the model microbe to investigate lipid production as an oleaginous fungus. Mitochondrial citrate transporter can catalyze the translocation of the ...citrate, accumulated from TCA cycle, across the mitochondrial inner membrane. The extra-mitochondrial citrate is then cleaved by ATP-citrate lyase to oxaloacetate (OAA) and acetyl-CoA. Acetyl-CoA together with NADPH generated in cytosol is used for fatty acid biosynthesis. Thus, citrate transporters provide a link between TCA cycle in mitochondria and fatty acid biosynthesis in cytosol. However, the role of citrate transporters for lipid accumulation in oleaginous fungi is not clear. Two genes coding for citrate transporters, named citrate transporter (ct) and tricarboxylate transporter (tct) respectively, were present in the genome of oleaginous fungus M. circinelloides WJ11, a high lipid producing strain (36%, lipid/cell dry weight). As the mutant of strain CBS 277.49 (15%, lipid/cell dry weight) has been constructed and its genetic engineering tools are available for gene manipulation, so in this work, we investigated the role of citrate transporters in regulating lipid biosynthesis by overexpressing the citrate transporters of M. circinelloides WJ11 in CBS 277.49. Results: Our results showed that overexpression of ct and tct led to increased lipid accumulation by 44% (from 13.0% to 18.8%, w/w, CDW) and 68% (from 13.0% to 21.8%, w/w, CDW), respectively. Moreover, extracellular citrate concentration in ct-overexpressing strains (4.91 mM) and tct-overexpressing (3.25 mM) were significantly decreased by 20% and 47% respectively compared to the control (6.09 mM). Furthermore, overexpression of the citrate transporter genes activated the downstream steps in lipid biosynthesis, such as ATP citrate lyase (acl gene) and fatty acid synthases (fas1 and fas2 genes), indicating a greater flux of carbon went into fatty acid biosynthesis. Conclusions: This is the first report showing that citrate transporters involved in lipid accumulation in M. circinelloides. Both citrate transporter and tricarboxylate transporter could transport mitochondrial citrate to cytoplasm, which could provide more citrate to be cleaved by increased ACL to provide more acetyl-CoA and NADPH for increased FAS to synthesize fatty acids, thus, play a vital role in lipid biosynthesis in oleaginous fungus M. circinelloides.
A simple, cost-effective and scalable approach for the synthesis of N-doped mesoporous carbons that are effective as ORR catalysts is reported. The synthesis procedure involves two steps: a) ...production of mesoporous carbons using a template-free approach based on the carbonization of citrate salts of zinc and calcium, and b) N-doping by heat treatment in the presence of melamine. The resulting N-doped carbon possess a high specific surface area, a porosity made up exclusively of mesopores and a large amount of nitrogen functionalities (∼8–9 wt%). When used as an electrocatalyst for the oxygen reduction reaction (ORR), the metal-free carbon materials predominantly catalyze the 4 e− process, with an onset potential of 0.9 V (vs. RHE) and a superior kinetic current density (∼17 mA cm−2) to that of Pt/C at ∼0.6 V under basic conditions. In addition, the developed catalysts show a higher stability than commercial Pt/C and excellent electrocatalytic selectivity against methanol crossover.
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•New composite gels are prepared for fire prevention and extinction in coal mines.•Sodium silicate gel is blended with ionic polyacrylamide or carboxymethyl cellulose gel.•Aluminum ...citrate (Al-Cit) is added as crosslinker to form interpenetrating network.•Gels with anionic polyacrylamide/Al-Cit show the best fire extinction performance.•They reduce fire-source temperature as well as CO generation.
Novel gel materials are proposed for fire prevention and extinction in coal mines, where spontaneous combustion of coal continues to pose a significant risk. Cationic polyacrylamide (CPAM), anionic polyacrylamide (HPAM), and carboxymethyl cellulose (CMC) were each introduced separately into a sodium silicate (WG) gel, to obtain three gels labeled as CPAM/WG, HPAM/WG, and CMC/WG. A crosslinking agent, aluminum citrate, was subsequently added to the HPAM/WG and CMC/WG gels to afford two novel interpenetrating network hydrogels, HPAM-Al3+/WG and CMC-Al3+/WG, respectively. Among the various gels, the HPAM-Al3+/WG hydrogel exhibits the best seepage capacity, water retention capacity, compressive strength, and inhibition characteristics, which effectively resolve the post-water-loss cracking and pulverization problems commonly associated with inorganic consolidated silica gels. The microstructures of all the gels were investigated by scanning electron microscopy and their inhibitory effects on the oxidation of hydroxyl and methylene groups in coal at high temperatures were analyzed by Fourier transform infrared spectroscopy. Elemental mapping by energy dispersive X-ray spectroscopy indicated that the inorganic silica gel blends uniformly with the polymeric gel. Fire extinction experiments indicated that the HPAM-Al3+/WG gel reduces the fire-source temperature, heat radiation, and CO generation. Thus, the HPAM-Al3+/WG gel is an ideal fire prevention and extinction material.
Bismuth has emerged as a promising anode material for sodium‐ion batteries (SIBs), owing to its high capacity and suitable operating potential. However, large volume changes during ...alloying/dealloying processes lead to poor cycling performance. Herein, bismuth nanoparticle@carbon (Bi@C) composite is prepared via a facile annealing method using a commercial coordination compound precursor of bismuth citrate. The composite has a uniform structure with Bi nanoparticles embedded within a carbon framework. The nanosized structure ensures a fast kinetics and efficient alleviation of stress/strain caused by the volume change, and the resilient and conductive carbon matrix provides an interconnected electron transportation pathway. The Bi@C composite delivers outstanding sodium‐storage performance with an ultralong cycle life of 30 000 cycles at a high current density of 8 A g−1 and an excellent rate capability of 71% capacity retention at an ultrahigh current rate of 60 A g−1. Even at a high mass loading of 11.5 mg cm−2, a stable reversible capacity of 280 mA h g−1 can be obtained after 200 cycles. More importantly, full SIBs by pairing with a Na3V2(PO4)3 cathode demonstrates superior performance. Combining the facile synthesis and the commercial precursor, the exceptional performance makes the Bi@C composite very promising for practical large‐scale applications.
A Bi nanoparticle@carbon composite is synthesized by a facile heating method from a commercial product of bismuth citrate. Superior sodium storage performance with ultralong cycle life of 30 000 cycles at 8 A g−1 and ultrahigh rate capability of 71% capacity retention at 60 A g−1 are obtained. Full cells by coupling with a well‐developed cathode also deliver impressive capacity and cyclability.
Flexible and stretchable electronics have received tremendous attention for next-generation human-friendly electronic applications. However, fabrication of transparent, fully recyclable and ...stretchable electronic sensors with low-temperature stability using biocompatible natural polymer-based hydrogels still remains a great challenge. In this study, a green and fully recyclable stretchable electronic sensor with high transparency and ultra-low operating temperature is constructed using ionic conductive gelatin organohydrogels. These gelatin organohydrogels are prepared by a simple strategy of immersing gelatin pre-hydrogels in citrate (Na
3
Cit) water/glycerol solutions. The existence of Na
3
Cit in the organohydrogel not only induces the formation of multiple non-covalent cross-linking points, endowing the organohydrogel with high mechanical performances, but also makes the organohydrogel have excellent ionic conductivity. The organohydrogel is also highly transparent and exhibits outstanding antifreezing properties. The mechanical robustness, conductivity and transparency of the organohydrogel can be well maintained even at −60 °C. As a result, a stretchable and transparent electronic sensor based on this organohydrogel is fabricated, which is strain-sensitive with a large linear sensing window and excellent stability. More importantly, the organohydrogel-based electronic sensor can be fully recycled due to the reversible non-covalently crosslinked structure, and the recycled organohydrogel regains its mechanical and sensing properties. The obtained sensors could precisely detect various human activities even below −30 °C, indicating the potential applications of the organohydrogel-based electronic sensor in flexible and stretchable electronics in a broad range of temperature.
A green, fully recyclable and stretchable electronic sensor based on ionic conductive gelatin organohydrogels can operate at ultra-low temperature.
Polyethylene (PE) microplastics retained in sewage sludge inevitably enter the anaerobic digestion system. To date, no information has been reported on the mechanisms of PE microplastics affecting ...anaerobic digestion of waste activated sludge (WAS). This study evaluated the mechanisms using batch and continuous tests. Short exposure to PE microplastics at lower levels (i.e., 10, 30, and 60 particles/g-TS) did not significantly affect the methane production, but higher levels of PE microplastics (i.e., 100 and 200 particles/g TS) significantly (P = 0.006 and 0.0003) decreased methane production by 12.4–27.5%, with a lower methane potential and hydrolysis coefficient. In continuous test over 130 days, feeding WAS with 200 particles PE microplastics/g TS decreased vs destruction by up to 27.3% (P = 2.18 × 10–18) and resulted in a 9.1% (P = 0.002) increase in the volume of digested sludge for disposal. Correspondingly, the microbial community was shifted in the direction against anaerobic digestion. A mechanisms study revealed that the negative effect of PE microplastics was likely attributed to the induction of reactive oxygen species (ROS) rather than the released acetyl tri-n-butyl citrate. The generation of ROS caused a 7.6–15.4% reduction of cell viability, thereby restraining sludge hydrolysis, acidification, and methanogenesis.
Nanoparticles of cobalt ferrite (CoFe2O4) were synthesized by the EDTA/Citrate complexing method and hydrothermal method without addition of surfactant. The influence of the pH of the reaction medium ...(8, 9 or 10), the temperature of the thermal treatment (600°C, 800°C or 1000°C for the EDTA/Citrate method, and 120°C, 140°C or 160°C for the hydrothermal method), and the duration of the thermal treatment (2, 4 or 6h for the EDTA/Citrate complexing method, and 6, 15 or 24h for the hydrothermal method) on the average crystallite size was studied by means of an experimental design based on the results obtained by XRD. Statistical analysis led to quantification of the influence of the synthesis parameters on the crystallite size of the powders. Results showed that the pH of the reaction medium is the parameter that shows the greatest influence on the growth of the crystallites of the powders obtained by the hydrothermal method, while calcination temperature is the most significant one for the powders produced by the EDTA/Citrate complexing method.
The ultrathin porous carbon shell with the thickness of about 10 nm has been fabricated by a facile method using sodium citrate as carbon precursor without any activation. The electric conductivity ...of the material is as high as 7.12 S/cm, which contributes to a good rate performance for supercapacitor electrode without any conductive additive. When tested in 6 M KOH by three-electrode system, the C-700 sample exhibits specific capacitance of 251 F g−1 at 1 A g−1, high rate capability with the specific capacitance of 228 F g−1 at 20 A g−1, only a loss of 3% after 10000 cycles at a current density of 3 A g−1. Non aqueous performance was tested in 1 M TEA-BF4/acetonitrile, the material can deliver an energy density of 12–17 Wh kg−1 in a two-electrode system. Apparently, the porous carbon with ultrathin structure can provide low-resistant pathways and short ion diffusion channels for energy storage. Therefore, the ultrathin porous carbon shell would be a promising material particularly for applications where high power output performances are required.
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•The flower globular magnesium hydroxide (FGMH) was synthesized for the first time.•The method using trisodium citrate as crystal modifier is mild and easy to operate.•The prepared ...materials exhibited good dispersion and high specific surface area.•FGMH particles with rough surface solve the problem of difficult filtration.•The max-adsorption capacity of the materials uptake Ni(II) ions was 287.11 mg/g.
To remove toxic Ni(II) ions from wastewater, a novel flower globular magnesium hydroxide (FGMH) was prepared by a gentle method using trisodium citrate as a crystal modifier. This material exhibited a high specific surface area. The synthesized products and adsorption mechanism for Ni(II) ions were examined by diverse characterization technologies and methods. FGMH was employed to remove Ni(II) ions by the adsorption method. The effects of various parameters, viz., the amount of adsorbent, contact time, temperature and pH, on the removal rate by the adsorbent were investigated in detail. The kinetic data fitted well with a pseudo-second-order model and experimental equilibrium adsorption data conformed to a Langmuir isotherm under optimized conditions. The optimal process parameters included 30 mg of FGMH, a 50 min contact time, pH values between 6.07 and 7.71 for the Ni(II) solution, and adsorption at room temperature for 50 mL of 80 mg/L Ni(II) solution. The percentage of removal efficiency was found to be above 92.64%, and the maximum adsorption capacity of MH was 287.11 mg/g under optimum adsorption conditions. The analyses indicated that the Ni(II) ions were chemisorbed on the FGMH surface.
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