Design and Synthesis Functional Selective Catalytic Reduction Catalyst for NOx Removal

AbstractMeOx-Cu-SSZ-13 (Me=Mn, Ce) was synthesized by physically mixing mental oxide and ion-exchanged zeolite. The composite catalyst showed highly efficient for the NOx removal using NH3-SCR method. And the NO conversion is 98% for MnOx-CeO2/Cu-SSZ-13 at 150°C and 97% for MnOx/Cu-SSZ-13 at 175°C. Meanwhile, the N2 selectivity remains more than 98%. The catalysts are characterized by using XRD and SEM. The XRD patterns show that all samples are highly crystallized and without impurities. The SEM demonstrates all samples have uniform crystal size. Composite catalyst especially combined with Cu-SSZ-13 has considerable potential as a catalyst in the area of NOx conversion

Intensification of microalgae drying and oil extraction process by vapor recompression and heat integration

Reducing energy penalty caused by drying and oil extraction is the most critical challenge in microalgae biodiesel production. In this study, vapor recompression and heat integration are utilized to optimize the performance of wet microalgae drying and oil extraction. In the microalgae drying stage, the hot exhaust stream is recompressed and coupled with wet microalgae to recover the condensate heat. In the oil extraction stage, the exergy rate of recovered solvent is also elevated by compressor and then exchanged heat with feed and bottom stream in the distillation column. Energy and mass balance of the intensified process is investigated and compared with the conventional microalgae drying-extraction process. The simulation results indicated that the total energy consumption of the intensified process can be saved by 52.4% of the conventional route

Gene Flow Risks From Transgenic Herbicide-Tolerant Crops to Their Wild Relatives Can Be Mitigated by Utilizing Alien Chromosomes

Integration of a transgene into chromosomes of the C-genomes of oilseed rape (AACC, 2n = 38) may affect their gene flow to wild relatives, particularly Brassica juncea (AABB, 2n = 36). However, no empiric evidence exists in favor of the C-genome as a safer candidate for transformation. In the presence of herbicide selections, the first- to fourth-generation progenies of a B. juncea × glyphosate-tolerant oilseed rape cross [EPSPS gene insertion in the A-genome (Roundup Ready, event RT73)] showed more fitness than a B. juncea × glufosinate-tolerant oilseed rape cross [PAT gene insertion in the C-genome (Liberty Link, event HCN28)]. Karyotyping and fluorescence in situ hybridization–bacterial artificial chromosome (BAC-FISH) analyses showed that crossed progenies from the cultivars with transgenes located on either A- or C- chromosome were mixoploids, and their genomes converged over four generations to 2n = 36 (AABB) and 2n = 37 (AABB + C), respectively. Chromosome pairing of pollen mother cells was more irregular in the progenies from cultivar whose transgene located on C- than on A-chromosome, and the latter lost their C-genome-specific markers faster. Thus, transgene insertion into the different genomes of B. napus affects introgression under herbicide selection. This suggests that gene flow from transgenic crops to wild relatives could be mitigated by breeding transgenic allopolyploid crops, where the transgene is inserted into an alien chromosome

Enhanced Plasticity and Corrosion Resistance in Mg-Zn-Ca-Cu Amorphous Alloy Composite via Plasma Electrolytic Oxidation Treatment

In this study, a dendrite-reinforced Mg-based amorphous alloy composite was prepared through an in situ precipitation strategy. After plasma electrolytic oxidation (PEO) treatment, the Mg85.1Zn12.7Ca2Cu0.2 amorphous alloy composite exhibited enhanced plasticity and corrosion resistance in a simulated body fluid solution (SBF). The PEO-treated composite showed a significant plastic strain of 10.5 ± 1.1%, as well as outstanding strain-hardening behavior. The enhancement of plasticity may be attributed to the in-situ formed coating, which can not only serve as a propagation barrier for shear bands but can also introduce nucleation sites in the bands as a result of stress mismatch and compositional heterogeneity. The corrosion density in the SBF decreased by three orders compared with the composite substrate. The spontaneous formation of apatite on the porous layer demonstrated that the prepared PEO coating has high bioactivity. The current work may provide a fundamental basis for developing biomedical Mg-based alloys with excellent comprehensive mechanical properties and corrosion resistance

Transformation of Lignin and Its Model Compounds into Value-Added Chemicals Using Sulfide Catalysts

Lignin is mainly composed of hydroxy-substituted or methoxylated phenyl propane structures and serves as the only renewable bulk feedstock in nature for producing aromatic chemicals. By using suitable catalysts, the long chain structures of lignin can be selectively broken down to obtain different target products. This has been regarded as an important approach for the comprehensive utilization of lignin. Due to the high activity of hydrodeoxygenation, transition metal sulfide catalysts have been used in lignin conversion in recent decades. In this review, the application of transition metal sulfide catalysts in the catalytic conversions of lignin and its model compounds are summarized. The active components, support materials, reaction conditions and reaction mechanism are presented in detail. The existing challenges of sulfide catalysts in the degradation of lignin are discussed. Finally, potential solutions and future trends of this field are presented

Combined Effects of Mechanical Strain and Hydroxyapatite/Collagen Composite on Osteogenic Differentiation of Rat Bone Marrow Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) represent a promising source for bone repair and regeneration. Recent lines of evidence have shown that appropriate strain could regulate the osteogenic differentiation of MSCs. Our previous study demonstrated that hydroxyapatite/collagen (HA/Col) composite also played an important role in the osteogenic differentiation of MSCs. The aim of this study is to investigate the effects of mechanical strain and HA/Col composite on the osteogenic differentiation of rat bone marrow derived MSCs (rBMSCs) in vitro. rBMSCs were treated with cyclic strain generated by a self-designed stretching device with or without the presence of HA/Col composite. Osteogenic differentiation levels were evaluated using reverse transcription polymerase chain reaction (RT-PCR), alkaline phosphatase spectrophotometry, and western blotting. The results demonstrated that mechanical strain combined with HA/Col composite could obviously induce the differentiation of rBMSCs into osteoblasts, which had a better effect than only mechanical strain or HA/Col composite treatment. This provides a new avenue for mechanistic studies of stem cell differentiation and a novel approach to obtain more committed differentiated cells

Giant enhancement in Goos-Hänchen shift at the singular phase of a nanophotonic cavity

In this letter, we experimentally demonstrate thirtyfold enhancement in Goos-Hänchen shift at the Brewster angle of a nanophotonic cavity that operates at the wavelength of 632.8 nm. In particular, the point-of-darkness and the singular phase are achieved using a four-layered metal-dielectric-dielectric-metal asymmetric Fabry-Perot cavity. A highly absorbing ultra-thin layer of germanium in the stack gives rise to the singular phase and the enhanced Goos-Hänchen shift at the point-of-darkness. The obtained giant Goos-Hänchen shift in the lithography-free nanophotonic cavity could enable many intriguing applications including cost-effective label-free biosensors.MOE (Min. of Education, S’pore)Published versio

A Review on the Progress in Nanoparticle/C Hybrid CMS Membranes for Gas Separation

Carbon molecular sieve (CMS) membranes are novel materials derived from the pyrolysis of the polymeric precursors and have a well-developed ultra-microporous structure that can separate small gas pairs with minor difference in diameter, and thus exhibit higher gas permeability and selectivity than polymeric membranes. However, the gas permeability for traditional pure CMS membranes now cannot satisfy the requirements of commercial applications due to their disordered pore structure and high gas molecular diffusion resistance. Incorporating functional materials into membrane precursors to fabricate hybrid CMS membranes has been regarded as an effective way to tune the disordered pore structure of traditional pure CMS membranes, and thus to greatly improve their gas permeability. Many nanoparticles have been tested as the functional foreign materials to fabricate the hybrid CMS membranes with more developed microporous structure and enhanced gas separation performance. This review discusses the hybridized nanoparticle selection and effect of the species, quantities and particle sizes of the foreign materials on CMS membrane characteristics and performance. The function of the materials incorporated inside the hybrid CMS membranes is also analyzed. It is identified that preparation of hybrid CMS membranes provides a simple and convenient route to efficiently improve the trade-off relationship between permeability and selectivity, and to enable the construction of carbon-based composite materials with novel functionalities in membrane science