Effect of kaolin additive on PM_2.5 reduction during pulverized coal combustion: Importance of sodium and its occurrence in coal

Si, Junping,Liu, Xiaowei,Xu, Minghou,Sheng, Lei,Zhou, Zijian,Wang, Chao,Zhang, Yang,Seo, Yong-Chil Elsevier 2014 APPLIED ENERGY Vol.114 No.-

<P><B>Abstract</B></P> <P>Little work has been performed on the importance of sodium and its occurrence in coal to PM<SUB>2.5</SUB> (particles less than 2.5μm in aerodynamic diameter) reduction by kaolin during O<SUB>2</SUB>/N<SUB>2</SUB> combustion and O<SUB>2</SUB>/CO<SUB>2</SUB> combustion at high temperatures. In this study, the combustion experiment of a treated low-sodium coal with sodium aluminosilicate additive was conducted in a lab-scale drop tube furnace (DTF) at 1500°C to reveal the contribution of mineral melting and coalescence to PM<SUB>2.5</SUB> reduction. Meanwhile, two typical Na-loaded coals (in which the sodium was loaded in the form of NaCl and sodium carboxylate, respectively) with kaolin added were also burnt under O<SUB>2</SUB>/N<SUB>2</SUB> and O<SUB>2</SUB>/CO<SUB>2</SUB> atmospheres to investigate the effect of interaction between kaolin and different chemical form sodium on PM<SUB>2.5</SUB> reduction. The results show that sodium aluminosilicate is able to promote the migration of PM<SUB>0.5–2.5</SUB> (particles in aerodynamic diameter of 0.5–2.5μm) to form coarse particles. Due to the stronger reactivity of sodium carboxylate reacting with kaolin than that of NaCl, PM<SUB>0.2–0.5</SUB> (particles in aerodynamic diameter of 0.2–0.5μm) decreases more significantly in the combustion when adding kaolin into the NaAc-loaded coal than into NaCl-loaded coal. In addition, the PM<SUB>0.2–0.5</SUB> reduction in O<SUB>2</SUB>/CO<SUB>2</SUB> combustion is lower than that in O<SUB>2</SUB>/N<SUB>2</SUB> combustion owing to the less vaporization of metals and the slower diffusion rate of vapors in the O<SUB>2</SUB>/CO<SUB>2</SUB> atmosphere in comparison to those in the O<SUB>2</SUB>/N<SUB>2</SUB> atmosphere. The mineral coalescence varied in interactions of kaolin with NaAc and NaCl. Besides, the PM<SUB>0.5–2.5</SUB> emission differed as a result of differences in coal characteristic and the atmosphere, and this would cause the difference of collision frequency between particles and additive. With the joint actions of mineral coalescence and particle collision, the NaAc-loaded coal has a higher PM<SUB>0.5–2.5</SUB> reduction by kaolin than NaCl-loaded coal, especially under the O<SUB>2</SUB>/N<SUB>2</SUB> combustion. An expression describing the relationship of PM<SUB>0.5–2.5</SUB> reduction, mineral coalescence and particle collision was fitted and it is found that the mineral coalescence has a stronger influence than particle collision on PM<SUB>0.5–2.5</SUB> reduction by kaolin.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The sodium aluminosilicate plays an important role in PM<SUB>2.5</SUB> reduction by kaolin. </LI> <LI> The capability of kaolin to reduce PM<SUB>2.5</SUB> depends on the sodium occurrence in coals. </LI> <LI> The effect of kaolin on PM<SUB>2.5</SUB> reduction becomes weaker during O<SUB>2</SUB>/CO<SUB>2</SUB> combustion. </LI> <LI> Particle collision may be taken into consideration for PM<SUB>2.5</SUB> reduction. </LI> </UL> </P>

Study on the Micro-vibration Suppression of a MnCu Spring Isolation Platform with Low Stiffness and High Damping

Xianbo Yin,Yang Xu,Xiaowei Sheng,Song Wan,Yixin Wang 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.3

Reaction wheels are the primary micro-vibration sources for microsatellites. To reduce the adverse effects of micro-vibrations, a six-degree-of-freedom (6-DOF) vibration isolation scheme with low stiffness and high damping is proposed. Through six-component force measurements, the harmonic characteristics of the micro-vibrations generated by a reaction wheel are determined. Based on an assumption of small deformation linear elasticity, a dynamic model of a convergent isolation platform is established. With high damping characteristics, helical springs made of MnCu (manganese copper) alloy are selected as the isolation element of the platform. After a modal analysis and stiffness design, the key structural parameters of the isolator are determined. According to the coupling of degrees of freedom, the transmissibility of the isolator is simulated and compared to titanium and aluminum alloys. Combined with on-ground and on-board tests, the effectiveness of the isolation platform is verified. The research shows that the 6-DOF isolation platform based on the MnCu spring realizes multidirectional low-frequency and low-magnitude micro-vibration suppression. The minimum initial isolation frequency of the designed isolator is 16.8 Hz, and the best suppression effect reaches 17.5 dB. The proposed isolator’s application successfully controls high-order harmonics and sensitive load response behaviors.

Vibration Energy Transfer Characteristics of Panels with Multiple Coupling Forms in Satellites

Yan Shen,Yang Xu,Xiaowei Sheng,Song Wan,Xianbo Yin 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.5

Micro-vibrations on-board a satellite have degrading effects on the performance of certain payloads like observation cameras. There are numerous sources and extremely complicated transfer paths for micro-vibration in satellites. The vibration energy transfer characteristics of panels with multiple coupling forms in satellites were analyzed, which can guide the vibration isolation measures of satellites. First, the satellite was divided into honeycomb panel subsystems with multiple coupling forms. In the next phase, based on the energy finite element analysis (EFEA), the energy finite element equation of the honeycomb subsystem and the connection matrix at the coupling boundary was established to determine the energy distribution and energy flow characteristics of the multiform coupled honeycomb panels under different excitation frequencies. Finally, the finite difference approximation based on the response obtained from the measurement point array was employed to obtain the energy density. By comparing the results of the experiment and EFEA simulation under different frequency excitations, the average error of the energy density was less than 4 dB, which proved the accuracy of EFEA in the transfer characteristics analysis of the vibration energy of the satellite. The experiment method of vibration transfer based on the finite difference approximation can directly obtain the energy density of the structure.

Defect-Induced Epitaxial Growth for Efficient Solar Hydrogen Production

Zhang, Kan,Kim, Jung Kyu,Park, Bumsu,Qian, Shifeng,Jin, Bingjun,Sheng, Xiaowei,Zeng, Haibo,Shin, Hyunjung,Oh, Sang Ho,Lee, Chang-Lyoul,Park, Jong Hyeok American Chemical Society 2017 Nano letters Vol.17 No.11

<P>Epitaxial growth suffers from the mismatches in lattice and dangling bonds arising from different crystal structures or unit cell parameters. Here, we demonstrate the epitaxial growth of 2D MoS2 ribbon on 1D CdS nanowires (NWs) via surface and subsurface defects. The interstitial Cd-0 in the (1(2)over-bar10) crystal plane of the [0001]-oriented CdS NWs are found to serve as nucleation sites for interatomically bonded [001]-oriented MoS2, where the perfect lattice match (similar to 99.7%) between the(10(1)over-bar1) plane of CdS and the (002)-faceted in-plane MoS2 result in coaxial MoS2 ribbon/CdS NWs heterojunction. The coaxial but heterotropic epitaxial MoS2 ribbon on the surface of CdS NWs induces delocalized interface states that facilitate charge transport and the reduced surface state. A less than 5-fold ribbon width of MoS2 as hydrogen evolution cocatalyst exhibits a similar to 10-fold H-2 evolution enhancement than state of the art Pt in an acidi electrolyte, and apparent quantum yields of 79.7% at 420 nm 53.1% at 450 nm, and 9.67% at 520 nm, respectively.</P>

The role of Jacalin-related lectin gene AOL_s00083g511 in the development and pathogenicity of the nematophagous fungus Arthrobotrys oligospora

Dong Xinyuan,Si Jiali,Zhang Guanghui,Shen Zhen,Zhang Li,Sheng Kangliang,Wang Jingmin,Kong Xiaowei,Zha Xiangdong,Wang Yongzhong 한국미생물학회 2021 The journal of microbiology Vol.59 No.8

Arthrobotrys oligospora is a model species of nematophagous fungi and has great potential for the biological control of nematode diseases. Lectin is a protein that binds to carbohydrates and their complexes with high specificity, which mediates recognition events in various physiological and pathological processes. This study aimed to investigate the role of the Jacalin-related lectin (JRL) gene, AOL_s00083g511, in A. oligospora development. Through a homology recombination approach, we obtained the AOL_s00083g511 knockout mutant strain (Δg511). Next, the biological characteristics of the Δg511 mutant strain, including growth rate, conidia germination rate, adaptation to environmental stresses, and nematocidal activity, were compared with those of the wild-type (WT) strain. The results showed that the JRL gene AOL_ s00083g511 did not affect fungal growth, conidia germination, 3D-trap formation, and the ability of A. oligospora to prey on nematodes significantly. We speculate that this phenomenon may be caused by a loss of the key β1–β2 loops in the AOL_ s00083g511-encoded JRL domain and an intrinsic genetic compensation of AOL_s00083g511 in this fungus. The growth rates of both strains on high salt or surfactant media were similar; however, in the strong oxidation medium, the growth rate of the Δg511 mutant was significantly lower than that of the WT strain, indicating that AOL_s00083g511 might play a role in oxidative stress resistance. These findings provide a basis for further analysis of the related functions of the JRL gene in A. oligospora and their potential roles in the biological control of nematodes in the future.

Double 2-dimensional H₂-evoluting catalyst tipped photocatalyst nanowires: A new avenue for high-efficiency solar to H₂ generation

Zhang, Kan,Qian, Shifeng,Kim, Wanjung,Kim, Jung Kyu,Sheng, Xiaowei,Lee, Jun Young,Park, Jong Hyeok Elsevier 2017 Nano energy Vol.34 No.-

<P><B>Abstract</B></P> <P>Asymmetric or symmetric metal-tipped one-dimensional (1D) semiconductors are promising systems for efficient photocatalytic reactions such as solar-to-fuel conversion because of ultrafast exciton dynamics that arise at the specific heterostructure interface. However, synthesizing such unique nanostructures experiencing colloid growth on noble metal that has faced a formidable challenge in practical application because these synthesis conditions are not suitable to deploy in mass production. Here, we report the gram-scale mass production of symmetric MoS<SUB>2</SUB>-tipped CdS nanowires (S-MtC NWs) via edge-terminated attachment in a binary solvent. The factors influencing the formation of symmetric heterostructures are investigated by varying the types of precursors, initial concentration, and solvent composition. Under visible-light irradiation (λ≥420nm), the S-MtC NWs exhibit superior photocatalytic H<SUB>2</SUB> evolution activity (12.6mmol/g/h) compared to common Pt/CdS NWs (2.6mmol/g/h), corresponding to an apparent quantum yield of 37.6% at 420nm. This impressive photocatalytic ability is ascribed to spatially separated redox-active sites in the S-MtC NWs, in which the reduction and oxidation sites are at the MoS<SUB>2</SUB> tip and the CdS stem, respectively. Additionally, it is found that the length of CdS NWs as higher aspect ratio as possible could get better photocatalyst H<SUB>2</SUB> performance. The symmetry of 2D MoS<SUB>2</SUB> tips and 1D CdS NWs may provide advanced avenues for specific co-catalyst decoration, enabling co-catalysts to be selectively located at reduction or oxidation sites for other targeted solar artificial syntheses.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Symmetric 2D tipped 1D heterostructured nanowires were synthesized. </LI> <LI> The tipped structure exhibited the spatially separated redox-active sites. </LI> <LI> Theoretical simulation demonstrated one order of magnitude decrease in energy barrier. </LI> <LI> The photocatalytic performance of symmetric heterostructure was superior to asymmetric counterpart. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Symmetric 2D tipped 1D heterostructured nanowires synthesized by edge-terminated attachment exhibit efficient spatial charge separation effect and the longer the better photocatalytic activity, resulting in photocatalytic H<SUB>2</SUB> activity of 12.6mmol/h·g with excellent long-term durability (>10h) without additional passivation under visible light (λ≥420nm).</P> <P>[DISPLAY OMISSION]</P>

The 14-3-3 Gene Function of Cryptococcus neoformans Is Required for its Growth and Virulence

( Jingbo Li ),( Yun C. Chang ),( Chun Hua Wu ),( Jennifer Liu ),( Kyung J. Kwon Chung ),( Sheng He Huang ),( Hiro Shimada ),( Rob Fante ),( Xiaowei Fu ),( Ambrose Jong ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.5

Cryptococcus neoformans is a life-threatening pathogenic yeast that causes devastating meningoencephalitis. The mechanism of cryptococcal brain invasion is largely unknown, and recent studies suggest that its extracellular microvesicles may be involved in the invasion process. The 14-3-3 protein is abundant in the extracellular microvesicles of C. neoformans, and the 14-3-3-GFP fusion has been used as the microvesicle’s marker. However, the physiological role of 14-3-3 has not been explored. In this report, we have found that C. neoformans contains a single 14-3-3 gene that apparently is an essential gene. To explore the functions of 14-3-3, we substituted the promoter region of the 14-3-3 with the copper-controllable promoter CTR4. The CTR4 regulatory strain showed an enlarged cell size, drastic changes in morphology, and a decrease in the thickness of the capsule under copper-enriched conditions. Furthermore, the mutant cells produced a lower amount of total proteins in their extracellular microvesicles and reduced adhesion to human brain microvascular endothelial cells in vitro. Proteomic analyses of the protein components under 14-3-3-overexpressed and -suppressed conditions revealed that the 14-3-3 function(s) might be associated with the microvesicle biogenesis. Our results support that 14-3-3 has diverse pertinent roles in both physiology and pathogenesis in C. neoformans. Its gene functions are closely relevant to the pathogenesis of this fungus.