Sulfate- and pH-driven metabolic flexibility in sugarcane vinasse dark fermentation stimulates biohydrogen evolution,sulfidogenesis or homoacetogenesis

Dark fermentation of sugarcane vinasse can be used as a “cleaning” step to remove sulfate prior to methanogenesis because sulfidogenic conditions can be successfully established in parallel with biohydrogen production. Using a 2² central composite rotational design (CCRD) and response surface methodology (RSM), this study assessed the impacts of bicarbonate and sulfate availability on the establishment of sulfidogenesis in the thermophilic (55 °C) fermentation of vinasse in batch reactors, equally assessing the impacts on biohydrogen evolution. CCRD-RSM results indicated the favoring of biohydrogen production at the lowest sulfate and bicarbonate concentrations, whilst the opposite was observed for sulfidogenesis. Glycerol, lactate, and hydrogen were the preferential electron donors utilized by sulfate-reducing bacteria (SRB), whilst ethanol was markedly consumed only at high sulfate concentrations. SRB were inhibited by sodium when dosing excess NaHCO₃ and Na₂SO₄. Complementary tests revealed maximum biohydrogen production (2.40 mmol) out of the CCRD, at pH exceeding 7.5 with no interference of sulfidogenesis. Non-efficient biohydrogen production was observed at low pH (<5.0; ～1.90 mmol) because the uptake of lactate was inhibited. Meanwhile, homoacetogenesis was established under intermediate pH range (5.5–6.5), as revealed by the accumulation of acetate (up to 2.5 g L^?1). 16S rRNA gene amplicon sequencing further revealed the genera Thermoanaerobacterium/Pseudoclostridium, Desulfotomaculum/Desulfohalotomaculum and Sporomusaceae/Moorella as the main biohydrogen-producing, sulfate-removing and biohydrogen-consuming (homoacetogens) microbial groups, respectively. Hence, using a single inoculum source, vinasse may provide a butyrate-rich (along with biohydrogen-rich biogas) or a sulfate-free and acetate-rich fermented effluent, depending mainly on proper pH control.     

Molecular fingerprint and machine learning to accelerate design of high-performance homochiral metal–organic frameworks

Computational screening was employed to calculate the enantioseparation capabilities of 45 functionalized homochiral metal–organic frameworks (FHMOFs), and machine learning (ML) and molecular fingerprint (MF) techniques were used to find new FHMOFs with high performance. With increasing temperature, the enantioselectivities for (R,S)-1,3-dimethyl-1,2-propadiene are improved. The “glove effect” in the chiral pockets was proposed to explain the correlations between the steric effect of functional groups and performance of FHMOFs. Moreover, the neighborhood component analysis and RDKit/MACCS MFs show the highest predictive effect on enantioselectivities among the four ML classification algorithms with nine MFs that were tested. Based on the importance of MF, 85 new FHMOFs were designed, and a newly designed FHMOF, NO₂-NHOH-FHMOF, with high similarity to the optimal MFs achieved improved chiral separation performance, with enantioselectivities of 85%. The design principles and new chiral pockets obtained by ML and MFs could facilitate the development of new materials for chiral separation.     

Rapid preparation of Palygorskite/Al2O3 composite aerogels with superhydrophobicity,high-temperature thermal insulation and improved mechanical properties

Al₂O₃ aerogels are widely employed in heat insulation and flame retardancy because of their unique combination of low thermal conductivity and exceptional high-temperature stability. However, the mechanical properties of Al₂O₃ aerogel are poor, and the preparation time is considerably long. In this study, we present a simple and scalable approach to construct monolithic Pal/Al₂O₃ composite aerogels using solvothermal treatment instead of traditional solvent replacement, which remarkably shortened the preparation time. Subsequently, to obtain stable superhydrophobicity (θ > 152°), the Pal/Al₂O₃ aerogel was modified by gas-phase modification method. The obtained Pal/Al₂O₃ composite aerogels demonstrate the integrated properties of low density (0.078–0.106 g/cm³), low thermal conductivity (1000 °C, 0.143 W/(m·K)), good mechanical properties (Young's modulus, 1.6 MPa), and good heat resistance. The monolithic Pal/Al₂O₃ composite aerogels with improved mechanical performance and improved thermal stability can show great potential in the field of thermal insulation.     

Nutrient enrichment of dairy curd by incorporation of whole and ruptured microalgal cells (Nannochloropsis salina)

This work investigated incorporation of Nannochloropsis salina into renneted dairy gels and curd. Whole and ruptured microalgal cells did not impair κ-casein macropeptide cleavage by the rennet enzyme. However, insoluble components of ruptured cells impeded gelation, presumably by hindering interactions between renneted casein micelles. Confocal imaging showed that whole cells were retained and homogenously distributed within the protein network of the gels and cooked curd, whereas ruptured algae formed large aggregates that altered the protein matrix. Eicosapentaenoic acid (EPA) in the whole microalgal cells was incorporated within the curds, with considerably less EPA retained for ruptured cells. Soluble algal debris did not impair gelation, however EPA wasn't retained in the curd. The study demonstrates that nutrient enrichment of renneted dairy products is possible by incorporating whole microalgal cells to displace milk fat with protein and the beneficial long-chain omega-3 fatty acid EPA. Future research into the optimisation of product organoleptic properties is required.     

High performance H2 sensor based on rGO-wrapped SnO2–Pd porous hollow spheres

Hydrogen (H₂) sensors based on metal oxide semiconductors (MOS) are promising for many applications such as a rocket propellant, industrial gas and the safety of storage. However, poor selectivity at low analyte concentrations, and independent response on high humidity limit the practical applications. Herein, we designed rGO-wrapped SnO₂–Pd porous hollow spheres composite (SnO₂–Pd@rGO) for high performance H₂ sensor. The porous hollow structure was from the carbon sphere template. The rGO wrapping was via self-assembly of GO on SnO₂-based spheres with subsequent thermal reduction in H₂ ambient. This sensor exhibited excellently selective H₂ sensing performances at 390 °C, linear response over a broad concentration range (0.1–1000 ppm) with recovery time of only 3 s, a high response of ～8 to 0.1 ppm H₂ in a minute, and acceptable stability under high humidity conditions (e. g. 80%). The calculated detection limit of 16.5 ppb opened up the possibility of trace H₂ monitoring. Furthermore, this sensor demonstrated certain response to H₂ at the minimum concentration of 50 ppm at 130 °C. These performances mainly benefited from the special hollow porous structure with abundant heterojunctions, the catalysis of the doped-PdO_x, the relative hydrophobic surface from rGO, and the deoxygenation after H₂ reduction.     

11-苄硒基十一羧酸铵盐的双重刺激响应性质

合成了一种对氧化还原(Redox)和CO_2/N_2具有双重刺激响应的表面活性剂11-苄硒基十一羧酸铵盐(BSeUA),分别利用傅里叶红外光谱、核磁共振和电喷雾质谱等手段研究了BSeUA在Redox和CO_2/N_2刺激响应前后的分子结构变化特征。结果表明,在过氧化氢和水合肼交替作用下,BSeUA分子中二价硒醚基团(-Se-)与相应的四价硒亚砜基团(-Se=O)之间可以氧化还原可逆互变,在CO_2和N_2交替作用下,BSeUA分子中羧酸根(-COO-)与相应的羧酸(-COOH)之间可以可逆互变,从而实现BSeUA对Redox和CO_2/N_2具有双重刺激响应。分别在Redox和CO_2/N_2刺激作用下,由BSeUA稳定的乳液可以在破乳和再乳化2种状态下开关可逆循环至少5次,且乳液粒径和稳定性未发生明显变化。     

Astragali Radix-derived nitrogen-doped porous carbon: An efficient electrocatalyst for the oxygen reduction reaction

The development of biomass-derived nitrogen-doped porous carbons (NPCs) for the oxygen reduction reaction (ORR) is important for sustainable energy systems. Herein, NPCs derived from Astragali Radix (AR) via a cost-effective strategy are reported for the first time. The as-prepared AR-950-5 catalyst shows a stacked layer-like structure and porosity. Notably, the optimized AR-950-5 delivers catalytic activity comparable to that of commercial Pt/C (C-Pt/C), with high onset potential, positive half-wave potential and large limiting current density. It also displays superior long-term stability and methanol tolerance for ORR. This work will pave the way for a new approach in the development of highly active and low-cost NPCs for fuel cells.     

Olfactory responses of Stegobium paniceum to different Chinese medicinal plant materials and component analysis of volatiles

Stegobium paniceum (L.) (Coleoptera: Anobiidae) is among the major pests of stored products, causing great damage to stored Chinese medicinal plant materials (CMPMs) in China. Effective control strategies are urgently needed. The aim of this study was to explore the role of volatile organic compounds in the host preference of S. paniceum. First, the olfactory behavioral responses of S. paniceum adults to volatiles from four CMPMs (Panax notoginseng, Angelica sinensis, Gastrodia elata, and Peucedanum praeruptorum) were tested in Y-tube olfactometer experiments. Then, the volatile composition of these plant materials were analyzed by gas chromatography-mass spectrometry (GC-MS). S. paniceum showed significant preferences for volatiles from the four CMPMs, compared with clean air (CA). When S. paniceum was presented with choices among different CMPMs, it showed the strongest preference for P. notoginseng, followed by A. sinensis, then G. elata, and P. praeruptorum. GC-MS analysis identified 43, 34, 28 and 60 components in the volatile profiles of P. notoginseng, A. sinensis, G. elata, and P. praeruptorum, respectively. Falcarinol (14.4%), 3-n-butyl phthalide (78.7%), p-cresol (40.1%), and β-pinene (29.1%) were the most abundant components of the volatiles of P. notoginseng, A. sinensis, G. elata, and P. praeruptorum, respectively. The olfactory responses of S. paniceum to the four CMPMs demonstrated that host-related volatiles play an important role in the host-searching process by adult beetles. This information will be useful for the development of safe and effective trapping strategies for this pest.     

Gas-assisted exfoliation of boron nitride nanosheets enhancing adsorption performance

A gas exfoliation strategy for controllable preparation of boron nitride (BN) nanosheets with few-layered structure were reported. The green exfoliation process provides the BN nanosheets remarkable increment of adsorption capacities to organic contaminants, which is ascribed to better exposure of active sites originating from the larger surface area and thinner layer. Moreover, the prepared BN also exhibits outstanding recyclability.