Hai-tao Zhang’s research while affiliated with Chinese Academy of Sciences and other places

A shielded geomagnetic field, also called the hypomagnetic field (HMF), interferes with the metabolic processes of various cells and animals exhibiting diverse effects in different models, however, its underlying mechanism remains largely unknown. In this study, we assessed the effect on the energy metabolism of SH-SY5Y cells in HMF and found that HMF-induced cell proliferation depends on glucose supply. HMF promoted SH-SY5Y cell proliferation by increasing glucose consumption rate via up-regulating anaerobic glycolysis in the cells. Increased activity of LDH, a key member of glycolysis, was possibly a direct response to HMF-induced cell proliferation. Thus, we unveiled a novel subcellular mechanism underlying the HMF-induced cellular response: the up-regulation of anaerobic glycolysis and repression of oxidative stress shifted cellular metabolism more towards the Warburg effect commonly observed in cancer metabolism. We suggest that cellular metabolic profiles of various cell types may determine HMF-induced cellular effects, and a magnetic field can be applied as a non-invasive regulator of cell metabolism.

Abstract The detection and study of the rotational motion of space debris, which is affected by environmental factors, is a popular topic. However, relevant research in extremely low-orbit regions cannot be conducted due to a lack of observational data. Here, we fill in the gaps to present the rotational evolution of Tiangong-1 in the 5 months prior to reentry. Derived from the changes in the relative distance of its two corner cube reflectors from satellite laser ranging data, the angular momentum of Tiangong-1, which is relatively stable during observation, deviates from its maximum principal axis of inertia and precesses around the normal direction of the orbital plane due to gravity gradient torque at an angle of $23.1^\circ \pm\,2.5^\circ$ 23.1∘±2.5∘ . Requiring consistency with the relationship between the angular momentum and precession rate leads to a solution for the rotation rate, which is thus found to increase. This result cannot be explained by any previously developed torque models. Hence, an atmospheric density gradient torque (ADGT) model that considers the torque generated by the change in atmospheric density with orbital altitude at the satellite scale is proposed to explain the rotational acceleration mechanism of extremely low-orbit objects. The numerical results show that the ADGT model provides a non-negligible ability to explain, but cannot fully describe, the acceleration effect. The data on the rotational evolution of Tiangong-1 can provide an important basis for aerodynamic model improvement by addressing minor factors omitted in previous models.

Accumulative evidence has shown the adverse effects of a geomagnetic field shielded condition, so called a hypomagnetic field (HMF), on the metabolic processes and oxidative stress in animals and cells. However, the underlying mechanism remains unclear. In this study, we evaluate the role of HMF on the regulation of cellular reactive oxygen species (ROS) in human neuroblastoma SH-SY5Y cells. We found that HMF exposure led to ROS decrease, and that restoring the decrease by additional H2O2 rescued the HMF-enhanced cell proliferation. The measurements on ROS related indexes, including total anti-oxidant capacity, H2O2 and superoxide anion levels, and superoxide dismutase (SOD) activity and expression, indicated that the HMF reduced H2O2 production and inhibited the activity of CuZn-SOD. Moreover, the HMF accelerated the denaturation of CuZn-SOD as well as enhanced aggregation of CuZn-SOD protein, in vitro. Our findings indicate that CuZn-SOD is able to response to the HMF stress and suggest it a mediator of the HMF effect. Electronic supplementary material The online version of this article (doi:10.1007/s13238-017-0403-9) contains supplementary material, which is available to authorized users.

Three dimensional graphene networks (3DGNs) are promising electrode materials in electrochemical applications because they provide short diffusion pathways for electrolyte ions and fast transport channels for electrons, and act as an ideal scaffold for forming composites with pseudocapacitive materials to obtain a synergistic effect. This review offers an overview of recent advances in the synthesis of 3DGNs and their composites as electrodes in supercapacitors. In particular, methods to enhance the capacitive performance of 3DGN-based supercapacitors are summarized. Prospects for the future development of 3DGNs are presented at the end.

Electrochemical impedance spectroscopy (EIS) is a very useful technique for studying electrochemical behavior. The ideal Nyquist plot of electrochemical impedance spectroscopy for an electrical double-layer capacitor (EDLC) consists of a 45° line in the high-middle frequency region and a vertical line in the low frequency region, which can be explained by the transmission line model with pore size distribution. However, a semicircle loop in the high frequency region has been found in many studies. Hence, in this study, an equivalent model is proposed, in which the semicircle loop is ascribed to the contact resistance and contact capacitance between particles of activate materials, and between the activated carbon (AC) electrode and current collector. The effects of the charging process, conductivities of the active material and electrolyte, content of conductive additive and binder, porous separator, mass loading, and exerted pressure to the electrode on the EIS spectra of EDLCs were experimentally investigated. Among these effects, the most significant factors were the charging cut-off voltage, conductivity of activated carbon, content of conductive additive, and exerted pressure.

The influence of sodium and potassium promoters on the structure and reaction behavior of an FeMn catalyst toward light olefin synthesis from syngas was investigated by N2 adsorption, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), CO/CO2 temperature-programmed desorption (CO/CO2-TPD), Mössbauer spectroscopy (MES) and CO+H2 reaction. We found that an increase in manganese improves the dispersion of the active Fe component and light olefin selectivity; however, excessive enrichment with the Mn promoter on the catalyst surface suppresses CO conversion. Potassium and sodium inhibit the reduction of the catalyst in H2 and improve the adsorption of CO2 and CO because of the enhanced surface basicity of the catalysts. After reduction with syngas (n H2/n CO=20) and reaction with syngas (n H2/n CO=3.5), the analysis of the bulk structure was compared with those of the FeMn, FeMnNa, and FeMnK catalysts. The results show that FeCx is found in relatively high levels in the FeMnK catalysts because of the stronger alkalinity and adsorbability of CO. However, Fischer-Tropsch synthesis (FTS) results indicate that sodium and potassium improved the selectivity toward light olefins. The best catalytic performance was achieved by the FeMnNa catalyst. Its CO conversion and light olefins selectivity were 96.2% and 30.5% (molar fraction), respectively.

Direct catalytic conversion of syngas to light alkenes was carried out on sodium promoted FeMn catalysts by co-precipitation-calcination-impregnation method. N-2-physisorption demonstrated that the addition of sodium decreased surface area. H-2-TPR revealed that excessive sodium inhibited reduction of catalysts. XRD and MES results indicated that sodium made carburization easy. The results showed that the addition of Na/Fe in the range of 0.7-3.5 mol% could improve the light alkene selectivity in syngas conversion. A maximum in CO conversion and light olefin selectivity were noted upon increasing sodium content (2.8 mol% Na/Fe) and then declined.

A series of potassium promoted Fe–Mn catalysts for light olefin synthesis from CO hydrogenation were prepared by the co-precipitation-calcination-impregnation method. The impact of potassium promoter on the textural properties, reduction behavior, adsorption of hydrogen, bulk phase composition and their correlation with Fischer–Tropsch synthesis (FTS) performances were emphatically studied. As revealed by N2 physisorption, the increasing of potassium had no distinct effect on the size of α-Fe2O3 and surface area. H2 temperature-programmed reduction/desorption showed that potassium inhibited the reduction and hydrogen adsorbability of catalysts. CO temperature-programmed desorption showed that potassium enhanced the CO adsorption of catalysts. X-ray photoelectron spectroscopy indicated the enrichment of promoter atoms on the surface of catalysts. The X-ray diffraction and Mössbauer effect spectroscopy results revealed that potassium made carburization easy. After reduction with syngas (H2/CO = 20) for 48 h, FTS test was performed with the syngas (H2/CO = 3.5) in the high temperature Fischer–Tropsch synthesis process. The maximum of CO conversion and selectivity to light olefins was noted on increasing K content (2.8 mol% K/Fe), followed by a significant decline at the excessive potassium level. At the point, the selectivity of light olefins and olefin/paraffin (C2–C4) was 27.75 mol% and 8.54. The results indicated that potassium promoter could inhibit the water gas shift reaction, suppress hydrogenation ability, which promoted the production of light olefins via suppressing the secondary hydrogenation reaction.