Poly(2,6-dimethyl-1,4-phenylene oxide) was tethered with a 1,5-disubstituted tetrazole through a quaternary ammonium linkage. The formation of a tetrazole-ion network in the resulting polymers was found to promote the hydroxide ion transport through the Grotthus-type mechanism.
Establishment of the regeneratable whole-cell catalyst platform for the production of biobased polymeric materials is a typical topic of synthetic biology. In this commentary, discovery story of a “lactate-polymerizing enzyme” (LPE) and LPE-based achievements for creating a new variety of polyesters with incorporated unnatural monomers are presented. Besides the importance of microbial platform itself is discussed referring to the “ballooning”-Escherichia coli.
A simple nitrobenzyl-umbelliferone (NCOU1) was synthesised containing a nitroreductase (NTR) trigger moiety. The presence of NTR, resulted in the fragmentation of the parent molecule and release of the highly emissive fluorophore umbelliferone via an NTR-catalyzed reduction of the nitro group. In the presence of the NTR enzyme, NCOU1 gave rise to a 5-fold increase in fluorescence intensity at 455 nm and was selective for NTR over other reductive enzymes. These results indicate that NCOU1 can be used as a simple assay for the detection of NTR.
This study described a template-free method for the synthesis of hierarchically macro-mesoporous Mn-TiO2 catalysts. The promoting effect of Mn doping and the hierarchically macro-mesoporous architecture on TiO2 based catalysts was also investigated for the selective reduction of NO with NH3. The results show that the catalytic performance of TiO2 based catalysts was improved greatly after Mn doping. Meanwhile, the Mn-TiO2 catalyst with the hierarchically macro-mesoporous architecture has a better catalytic activity than that without such an architecture.
The slag samples taken from landfill, which originated from different metallurgical processes, have been characterized in this study. The slags were categorized as electric arc furnace (EAF) slag, argon oxygen decarburization/metal refining process slag and vacuum oxygen decarburization slag based on chromium content and basicity. EAF slags have higher potential in metal recovery than the other two slags due to its higher iron and chromium contents. The size of the iron-chromium-nickel alloy particles varies from a few μm up to several cm. The recoveries of large metal particles and metal-spinel aggregates have potential to make the metal recovery from landfilled slags economically viable.
There is currently a growing interest in the realisation and optimization of hybrid plasma/catalyst systems for a multitude of applications, ranging from nanotechnology to environmental chemistry. In spite of this interest, there is, however, a lack in fundamental understanding of the underlying processes in such systems. While a lot of experimental research is already being carried out to gain this understanding, only recently the first simulations have appeared in the literature. In this contribution, an overview is presented on atomic scale simulations of plasma catalytic processes as carried out in our group. In particular, this contribution focusses on plasma-assisted catalyzed carbon nanostructure growth, and plasma catalysis for greenhouse gas conversion. Attention is paid to what can routinely be done, and where challenges persist.
This paper overviews the development of the anthraquinone auto-oxidation (AO) process for the production of hydrogen peroxide in China and abroad. The characteristics and differences between the fixed-bed and fluidized-bed reactors for the AO process are presented. The detailed comparison indicates that the production of hydrogen peroxide with the fluidized-bed reactor has many advantages, such as lower operation cost and catalyst consumption, less anthraquinone degradation, higher catalyst utilization efficiency, and higher hydrogenation efficiency. The key characters of the production technology of hydrogen peroxide based on the fluidized-bed reactor developed by the Research Institute of Petroleum Processing, Sinopec are also disclosed. It is apparent that substituting the fluidized-bed reactor for the fixed-bed reactor is a major direction of breakthrough for the production technology of hydrogen peroxide in China.
Rhamnolipids are a class of biosurfactants that have a great potential to be used in industries. Five proteins/enzymes, namely RhlA, RhlB, RhlC, RhlG and RhlI, are critical for the production of rhamnolipids in Pseudomonas aeruginosa. Four of the 5 proteins except RhlC were successfully over-expressed in E. coli and three of them (RhlA, RhlB and RhlI) were purified and obtained in milligram quantities. The purified proteins were shown to be folded in solution. Homology models were built for RhlA, RhlB and RhlI. These results lay a basis for further structural and functional characterization of these proteins in vitro to favor the construction of super strains for rhamnolipids production.
Overproduction of small-molecule chemicals using engineered microbial cells has greatly reduced the production cost and promoted environmental protection. Notably, the rapid and sensitive evaluation of the in vivo concentrations of the desired products greatly facilitates the optimization process of cell factories. For this purpose, many genetic components have been adapted into in vivo biosensors of small molecules, which couple the intracellular concentrations of small molecules to easily detectable readouts such as fluorescence, absorbance, and cell growth. Such biosensors allow a high-throughput screening of the small-molecule products, and can be roughly classified as protein-based and RNA-based biosensors. This review summarizes the recent developments in the design and applications of biosensors for small-molecule products.
The production of bio-hydrogen from raw cassava starch via a mixed-culture dark fermentation process was investigated. The production yield of H2 was optimized by adjusting the substrate concentration and the microorganism mixture ratio. A maximum H2 yield of 1.72 mol H2/mol glucose was obtained with a cassava starch concentration of 10 g/L to give a 90% utilization rate. The kinetics of the substrate utilization and of the generation of both hydrogen and volatile fatty acids were also investigated. The substrate utilization follows pseudo first order reaction kinetics, whereas the production of both H2 and the VFAs correlate with the Gompertz equation. These results show that cassava is a good candidate for the production of biohydrogen.
The ability to go from a digitized DNA sequence to a predictable biological function is central to synthetic biology. Genome engineering tools facilitate rewriting and implementation of engineered DNA sequences. Recent development of new programmable tools to reengineer genomes has spurred myriad advances in synthetic biology. Tools such as clustered regularly interspace short palindromic repeats enable RNA-guided rational redesign of organisms and implementation of synthetic gene systems. New directed evolution methods generate organisms with radically restructured genomes. These restructured organisms have useful new phenotypes for biotechnology, such as bacteriophage resistance and increased genetic stability. Advanced DNA synthesis and assembly methods have also enabled the construction of fully synthetic organisms, such as J. Craig Venter Institute (JCVI)-syn 3.0. Here we summarize the recent advances in programmable genome engineering tools.
In-line hydro-treatment of bio-oil vapor from fast pyrolysis of lignocellulosic biomass (hydro-pyrolysis of biomass) is studied as a method of upgrading the liquefied bio-oil for a possible precursor to green fuels. The nobel metal (Pt) and non-noble metal catalysts (Mo2C and WC) were compared at 500 °C and atmospheric pressure which are same as the reaction conditions for fast pyrolysis of biomass. Results indicated that under the pyrolysis conditions, the major components, such as acids and carbonyls, of the fast pyrolysis bio-oil can be completely and partially hydrogenated to form hydrocarbons, an ideal fossil fuel blend, in the hydro-treated bio-oil. The carbide catalysts perform equally well as the Pt catalyst regarding to the aliphatic and aromatic hydrocarbon formation (ca. 60%), showing the feasibility of using the cheap non-noble catalysts for hydro-pyrolysis of biomass.
With the recent emphasis and development of sustainable chemistry, the conversion of biomass feedstocks into alternative fuels and fine chemicals over various heterogeneous catalysts has received much attention. In particular, owing to their uniform micropores, strong acidity, and stable and rigid frameworks, zeolites as catalysts or co-catalysts have exhibited excellent catalytic performances in many reactions, including hydrodesulfurization, Fischer-Tropsch synthesis, and hydrodeoxygenation. However, the relatively small sizes of the zeolite micropores strongly limit the conversion of bulky biomolecules. To overcome this issue, mesoporous zeolites with pores larger than those of biomolecules have been synthesized. As expected, these mesoporous zeolites have outperformed conventional zeolites with improved activities, better selectivities, and longer catalyst lives for the upgrading of pyrolysis oils, the transformation of lipids into biofuels, and the conversion of glycerol into acrolein and aromatic compounds. This review briefly summarizes recent works on the rational synthesis of mesoporous zeolites and their superior catalytic properties in biomass conversion.
Perchlorate has recently emerged as a widespread environmental contaminant of healthy concern. Development of novel detection methods for perchlorate with the potential for field use has been an urgent need. The investigation has shown that surface-enhanced Raman scattering (SERS) technique has great potential to become a practical analysis tool for the rapid screening and routine monitoring of perchlorate in the field, particularly when coupled with portable/handheld Raman spectrometers. In this review article, we summarize progress made in SERS analysis of perchlorate in water and other media with an emphasis on the development of SERS substrates for perchlorate detection. The potential of this technique for fast screening and field testing of perchlorate-contaminated environmental samples is discussed. The challenges and possible solutions are also addressed, aiming to provide a better understanding on the development directions in the research field.
We have successfully prepared a series of Pd-Ni/TiO2 catalysts by a one-step impregnation-reduction method. Among these catalysts with different compositions of Ni and Pd, the one with the Ni:Pd ratio of 2.95 showed the best activity. Small monodispersed Pd-Ni bimetallic nanoparticles were loaded on the surface of titanium oxide nanopowder as confirmed with TEM and EDS mapping. The XPS analysis demonstrated that Pd exists as 31% Pd(II) species and 69% Pd(0) species and all nickel is Ni(II). The prepared Pd-Ni/TiO2 exhibited enhanced catalytic activity compared to an equal amount of Pd/TiO2 for Suzuki-Miyaura reactions together with excellent applicability and reusability.
A variety of pyrazole derivatives containing 1,3,4-thiadiazole moiety were synthesized under micro-wave irradiation, and their structures were confirmed by 1H NMR and HRMS. They were evaluated for herbicidal and antifungal activities, and the results indicated that two compounds with a phenyl group (6a) and 4-tert-butylphenyl group (6n) possess good herbicidal activity for dicotyledon Brassica campestris and Raphanus sativus with the inhibition of 90% for root and 80%–90% for stalk at 100 ppm respectively. The structure-activity relationship of compounds 6a and 6n was also studied by density function theory method.
A palladium catalyst supported on 2-aminopyridine functionalized cellulose was synthesized and fully characterized by inductively coupled plasma atomic emission spectroscopy, transmission electron microscope, Fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectrometry. This catalyst can be applied in the Suzuki cross-coupling reaction of aryl halides with arylboronic acids in 50% ethanol to afford biaryls in good yields, and easily recycled by simple filtration after reaction without the loss of metal Pd.
Great interests have arisen over the last decade in the development of hierarchically porous materials. The hierarchical structure enables materials to have maximum structural functions owing to enhanced accessibility and mass transport properties, leading to improved performances in various applications. Hierarchical porous materials are in high demand for applications in catalysis, adsorption, separation, energy and biochemistry. In the present review, recent advances in synthesis routes to hierarchically porous materials are reviewed together with their catalytic contributions.
Cell surface protein engineering facilitated by accumulation of information on genome and protein structure involves heterologous production and modification of cell surface proteins using genetic engineering, and is important for the development of high-performance whole-cell catalysts. In this field, cell surface display is a major technology by exposing target proteins, such as enzymes, on the cell surface using a carrier protein. The target proteins are fused to the carrier proteins that transport and tether them to the cell surface, as well as to a secretion signal. This paper reviews cell surface display systems for prokaryotic and eukaryotic cells from the perspective of carrier proteins, which determine the number of displayed molecules, and the localization, size, and direction (N- or C-terminal anchoring) of the passengers. We also discuss advanced methods for displaying multiple enzymes and a new method for the immobilization of whole-cell catalysts using adhesive surface proteins.
