In this study, an integrated vector-based three-dimensional (3D) methodology for the life cycle sustainability assessment (LCSA) of chemical process alternatives is proposed. In the methodology, a 3D criteria assessment system is first established by using the life cycle assessment, the life cycle costing, and the social life cycle assessment to determine the criteria from the environmental, economic, and social pillars, respectively. The methodology incorporates the analytic hierarchy process (AHP) method to convert experts’ judgments on the soft criteria into quantitative data and realize a unitary scale for both quantified soft criteria and normalized hard criteria. After assigning appropriate weights to each pillar and criterion by using the AHP method, the sustainability of the alternative processes can be prioritized by employing a novel vector-based algorithm, which combines the absolute sustainability performance and the relative sustainability deviation of the investigated processes. A case study on the sustainability assessment of three alternative ammonia production processes demonstrates that the proposed methodology is able to serve as a comprehensive and rigorous tool for the stakeholders to rank and identify the most sustainable chemical process alternatives.

We describe here a novel approach to enhance the transcription of a target gene in cell-free systems by symmetrically introducing duplex aptamers upstream to a T7 promoter in both the sense and antisense strands of double-stranded plasmids, which leads to the formation of a DNA bubble due to the none-complementary state of the ssDNA region harboring the aptamer sequences. With the presence of thrombins, the DNA bubble would be enlarged due to the binding of aptamers with thrombins. Consequently, the recognition region of the promoter contained in the DNA bubble can be more easily recognized and bound by RNA polymerases, and the separation efficiency of the unwinding region can also be significantly improved, leading to the enhanced expression of the target gene at the transcriptional level. The effectiveness of the proposed gene regulation system was demonstrated by enhancing the expression of gfp and ecaA genes in cell-free systems.Keywords: aptamer; DNA bubble; gene expression regulation; promoter;

Large scale and homogenous bernal-stacked bilayer (AB-stacked) graphene is a promising 2D functional material due to its distinct electronic properties. As motivated by some evidence, the continuous carbon radicals (e.g., ·CH3) can greatly contribute to the nucleation and growth of second layer graphene film; thus, overcoming the self-limited catalysis regime of metallic Cu surface by conventional chemical vapor deposition. Herein, a two-step reaction system is designed to facilitate more continuously supplying reactive intermediate for the second layer growth of graphene. With this strategy, monolayer and AB-stacked bilayer graphene films can be controllably grown by simply tuning the confined amount of predeposited amorphous carbon (α-C) under atmospheric pressure rather than low pressure or vacuum. This approach opens a straightforward way to grow 2D materials by managing the surficially catalytic kinetics in the two separated reaction units.

•Coral-/Urchin-Like Co3O4 have been fabricated by seed-mediated growing strategy.•Coral-/Urchin-Like Co3O4 own both mesopores and macropores.•Coral-/Urchin-Like Co3O4 display good photocatalytic performance and reusability.Three-dimensional (3D) hierarchical architectures built from spherical assembly of nanowires/nanorods have found applications in a wide range of fields. However, although some literatures have reported their successful preparation, up to now, it is difficult to adjust the size of the building blocks of the 3D structures, which indeed largely affects the performance of the materials. In this work, by adopting metal ions and PVP modified carbon spheres as templates, we demonstrate a seed-mediated growing strategy to control Co3O4 shapes to be 3D urchin-like hierarchical structures constructed from 40 nm-diameter nano-wires, or 3D coral-like ones assembled from thicker 100 nm-diameter nano-rods. XRD patterns show both structured Co3O4 are cubic phase, and N2 sorption demonstrates they own both mesopores and macropores. Besides, the obtained materials display good photocatalytic performance and reusability to degrade Congo Red dye.Schematic illustration of the synthetic routes for urchin-like and coral-like Co3O4 hollow structure.Download high-res image (176KB)Download full-size image

•A regulatable gene expression system was developed.•The regulatable system could change the state of gene expression.•The regulatable system could control metabolic flux.•The regulatable system can be a powerful tool for metabolic engineering.Artificial control of bio-functions through regulating gene expression is one of the most important and attractive technologies to build novel living systems that are useful in the areas of chemical synthesis, nanotechnology, pharmacology, cell biology. Here, we present a novel real-time control system of gene regulation that includes an enhancement element by introducing duplex DNA aptamers upstream promoter and a repression element by introducing a RNA aptamer upstream ribosome binding site. With the presence of ligands corresponding to the DNA aptamers, the expression of the target gene can be potentially enhanced at the transcriptional level by strengthening the recognition capability of RNAP to the recognition region and speeding up the separation efficiency of the unwinding region due to the induced DNA bubble around the thrombin-bound aptamers; while with the presence of RNA aptamer ligand, the gene expression can be repressed at the translational level by weakening the recognition capability of ribosome to RBS due to the shielding of RBS by the formed aptamer-ligand complex upstream RBS. The effectiveness and potential utility of the developed gene regulation system were demonstrated by regulating the expression of ecaA gene in the cell-free systems. The realistic metabolic engineering application of the system has also tested by regulating the expression of mgtC gene and thrombin cDNA in Escherichia coli JD1021 for controlling metabolic flux and improving thrombin production, verifying that the real-time control system of gene regulation is able to realize the dynamic regulation of gene expression with potential applications in bacterial physiology studies and metabolic engineering.

•MgO nanomaterials were prepared by using a novel microemulsion-based method.•The precursor grows via the “interface-controlled” homogeneous precipitation.•Material morphology can be manipulated by varying the calcination temperatures.This paper presented a novel microemulsion-based method for the preparation of MgO nanomaterials. Briefly, in a paraffin-in-water microemulsion system, we firstly synthesized Mg5(CO3)4(OH)2·4H2O/paraffin composites, the precursor of MgO, via an interface-controlled homogenous precipitation. By calcinating the composite precursor at different temperatures, MgO nanomaterials with varied morphologies could be obtained. A flower-like 3D hierarchical structure was achieved when applying lower calcination temperatures, which indeed preserves the morphology of the composite precursor. While at higher calcination temperatures, one can get the well-defined MgO nanoparticles. The prepared materials were thoroughly characterized by XRD, SEM and BET methods, and their application as adsorbents to remove Congo red from wastewater was demonstrated.

In this study, a novel engineering Escherichia coli strain (CBMG111) with the expression of mgtCB gene was constructed for the enhanced fermentative production of succinic acid by utilizing the synergetic effect of mgtC gene to improve the growth of strains at the environment of low Mg2+ concentration and mgtB to enhance the transport of Mg2+ into cells. After the effect of the expression of the individual genes (mgtA, mgtB, mgtC) on the growth of E. coli was clarified, the fermentative production of succinic acid by CBMG111 was studied with the low-price mixture of Mg(OH)2 and NH3·H2O as the alkaline neutralizer and the biomass hydrolysates as the carbon sources, which demonstrated that the expression of mgtCB gene can significantly increase the productivity of succinic acid (2.97 g L−1 h−1) compared with that by using the engineering strain with the overexpression of mgtA gene.

Chromium salts are a group of important chemical raw materials with many applications. While the conventional manufacturing process, i.e. calcium roasting of chromite, has many disadvantages; the novel processes of liquid-phase oxidation, whose main reaction is the oxidation of chromite by oxygen (air) in highly concentrated alkaline solutions, are promising to achieve clean manufacturing. For the oxidation reaction of chromite in NaOH solutions, a significant amount of multicomponent systems consisting NaOH, Na2CrO4, Na2SiO3, and NaAlO2 are generated. It is a prerequisite to clarify the solubility equilibrium of the multicomponent systems for exploring highly efficient separation methods of Na2CrO4 with Na2SiO3 and NaAlO2. In this paper, Na2CrO4 solubility in the ternary system of NaOH–H2O–Na2CrO4 was first measured using the equilibrium analysis method and varying the NaOH concentrations from 100 to 800 g·L–1 and the temperatures from 353.15 to 403.15 K. Aferwards, the solubility of Na2CrO4, NaAlO2, and Na2SiO3 in the other multicomponent systems was analyzed at NaOH concentration = 400, 500, and 600 g·L–1, respectively.

•GM(1,N) is used for predicting the yield of biohydrogen.•The method has high predictability under the condition of scanty data.•The predicted values are certain in each running of the computer codes.•The affecting extent of each factor on the yield of biohydrogen can be identified.Biohydrogen technology is regarded as one of the most promising ways for hydrogen production with the considerations of economic priority and environmental performance. In this study, grey model is used to predict the yield of biohydrogen under scanty data condition. An illustrative case has been studied by the proposed method, and pH, glucose and iron sulfate concentration are used as the independent variables, the yield of biohydrogen is used as dependent variable in the grey prediction model, and 9 groups of data are used as the training samples and another 2 groups of data are used as the test samples, the results show that the proposed method is feasible to predict the yield of biohydrogen under scanty data condition and the effect of the influencing factors on the yield could also be identified. According to the comparison with the results predicted by artificial neural network, it could be concluded that grey model has better predictability with scanty data. This method could be popularized to other biohydrogen systems.

Synthesis of the fragrant compound Calone 1951® from 4-methyl catechol and methyl bromoacetate entails three successive reactions: the Williamson reaction, Dieckmann condensation, and hydrolysis-decarboxylation reaction. In this paper, the synthesis of 4-methylcatechol dimethylacetate (MCDA) via the Williamson reaction by adding KI as catalyst was investigated. It was found that the addition of an appropriate amount of KI can significantly increase the product yield due to generation of methyl iodoacetate via the reaction between KI and methyl bromoacetate. The synthesised MCDA as well as Calone 1951® were first characterised by melting points, HPLC, IR, and NMR analyses. Next, the effect of the key operating factors on MCDA synthesis by the Williamson reaction was investigated and the optimum operating conditions were obtained via a group of orthogonal experiments. The verification experiments demonstrated that, under the optimum operating conditions, the MCDA yield could be increased from 78.5 % to 95.4 % by the addition of an appropriate amount of KI; the corresponding yield of Calone 1951® increased to 68 %.

•Special synthetic routes for Dual-Porosity Mn2O3 Cubes.•Mn2O3 Cubes contain both macropores and mesopores.•Dual-porosity Mn2O3 Cubes show great adsorption capacity for Congo Red.Dual-porosity materials containing both macropores and mesopores are highly desired in many fields. In this work, we prepared dual-porosity Mn2O3 cube materials with large-pore mesopores, in which, macropores are made by using carbon spheres as the hard templates, while the mesopores are produced via a template-free route. The attained dual-porosity Mn2O3 materials have 24 nm of large-pore mesopores and 700 nm of macropores. Besides, the achieved materials own cubic morphologies with particle sizes as large as 6.0 μm, making them separable in the solution by a facile natural sedimentation. Dye adsorption measurements reveal that the dual-porosity materials possess a very high maximum adsorption capacity of 125.6 mg/g, much larger than many reported materials. Particularly, the adsorbents can be recycled and the dye removal efficiency can be well maintained at 98% after four cycles. Adsorption isotherm and kinetics show that the Langmuir model and the pseudo-second-order kinetics model can well describe the adsorption process of Congo Red on the dual-porosity Mn2O3 cube materials. In brief, the reported dual-porosity Mn2O3 demonstrates a good example for controlled preparation of dual-porosity materials with large-pore mesopores, and the macropore-mesopore dual-porosity distribution is good for mass transfer in dye adsorption application.Download high-res image (119KB)Download full-size image

In this work, we presented a novel route to synthesize boron doped reduced graphene oxide (rGO) by using the dielectric barrier discharge (DBD) plasma technology under ambient conditions. The doping of boron (1.4 at%) led to a significant improvement in the capacitance of rGO and supercapacitors based on the as-synthesized B-rGO exhibited an outstanding specific capacitance.