Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology submitted time 2016-05-08
Abstract:
Peer Review Status:Awaiting Review
Subjects: Chemistry >> Physical Chemistry submitted time 2017-11-05 Cooperative journals: 《结构化学》
Abstract: A dinuclear dysprosium(III) compound, [Dy2(µ2-OH)2(QLC)4(1,10-phen)2]·4H2O (1) (QLC‒ = 2-quinolinecarboxylate and 1,10-phen = 1,10-phenanthroline), was synthesized and structurally and magnetically characterized. Compound 1 crystallizes in triclinic system, space group P with a = 10.9439(3), b = 11.2823(3), c = 12.2323(4) Å, α = 107.446(3), β = 91.700(3), γ = 91.511(2)°, V = 1439.25(8) Å3, Z = 1, C64H50N8O14Dy2, Mr = 1480.12, Dc = 1.708 g/cm3, μ = 2.653 mm−1 and F(000) = 734. The final R = 0.0366 and wR = 0.0736 for 5816 observed reflections with I > 2σ(I). Compound 1 contains the mononuclear [Dy(QLC)2(1,10-phen)] subunit formed from one 1,10-phen and two QLC‒ ligands chelating Dy(III) ion. Two mononuclear [Dy(QLC)2(1,10-phen)] subunits are bridged by a pair of µ2-OH groups to give a centrosymmetric dinuclear [Dy2(µ2-OH)2(QLC)4(1,10-phen)2] with each Dy(III) ion being eight-coordinated. Detailed susceptibility measurements revealed that compound 1 does not show slow magnetic relaxation under zero direct-current field but exhibits field-induced slow magnetic relaxation under 2 kOe applied field.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: A novel high-frequency and high power density planar insulated core transformer (PICT) applied to high voltage direct current (DC) generator is introduced. PICT’s operating principle and fundamental configuration are described, and preliminary experimental results in self-designed PICT apparatus are presented. Emphatically, magnetic leakage flux (MFL) giving rise to the output voltage drop is analyzed in detail both theoretically and by finite element method (FEM). Showing good consistency with experimental result, FEM simulation is considered to be practicable in physical design of PICT. To cancel out leakage inductance and improve the voltage uniformity, compensation capacitor is adopted and experimental verification is also presented. All shows satisfactory results.
Subjects: Biology >> Biophysics submitted time 2016-05-12
Abstract: The neural correlates of associative memory in healthy older adults were investigated by examining the correlation of associative memory performance with spontaneous brain oscillations. Eighty healthy older adults underwent a resting-state functional MRI and took a paired-associative learning test (PALT). Correlations between the amplitude of low-frequency fluctuations (ALFF) as well as fractional ALFF (fALFF) in the whole brain and PALT scores were calculated. We found that spontaneous activity as indexed by both ALFF and fALFF in the parahippocampal gyrus (PHG) was significantly positively correlated with associative memory performance, suggesting that the PHG plays a critical role in associative memory in older people.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-12
Abstract: Pneumolysin is one of the major virulence factors elaborated by Streptococcus pneumoniae; this toxin is a member of the cholesterol-dependent cytolysins. Engagement of cholesterol induces the formation of a multi-subunit complex by pneumolysin that lyses host cells by forming pores on the membrane. Because pneumolysin released by bacteria which have been killed by conventional antibiotics is still active, agents capable of directly attacking the toxin are considered advantageous against antimicrobials in the treatment of S. pneumoniae infections. Here we found that the phytosterol, beta-sitosterol, effectively protects against cell lysis caused by pneumolysin. This compound interacts with the toxin at Thr459 and Leu460, two sites important for being recognized by its natural ligand, cholesterol. Similar to cholesterol, beta-sitosterol induces pneumolysin oligomerization. This compound also protects cells from damage by other cholesterol-dependent toxins. Finally, this compound protects mice against S. pneumoniae infection. Thus, beta-sitosterol is a candidate for the development of anti-virulence agents against pathogens that rely on cholesterol-dependent toxins for successful infections.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Geography submitted time 2022-01-30 Cooperative journals: 《干旱区科学》
Abstract:The Central Tianshan Block is one of numerous microcontinental blocks within the Central Asian Orogenic Belt (CAOB) that overlies Precambrian basement rocks. Constraining the evolution of these ancient basement rocks is central to understanding the accretionary and collisional tectonics of the CAOB, and their place within the Rodinia supercontinent. However, to date, the timing and tectonic settings in which the basement rocks in the Central Tianshan Block formed are poorly constrained, with only sparse geochemical and geochronological data from granitic rocks within the northern segment of the block. Here, we present a systematic study combining UPb geochronology, whole-rock geochemistry, and the SrNd isotopic compositions of newly-identified granitic gneisses from the Bingdaban area of Central Tianshan Block. The analyzed samples yield a weighted mean Neoproterozoic 206Pb/238U ages of 975911 Ma. These weakly-peraluminous granitic rocks show a common geochemical I-type granite affinity. The granitic gneisses are calc-alkaline and enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), but they are depleted in high field strength elements (HFSEs); these characteristics are similar to those of typical subduction-related magmatism. All samples show initial (87Sr/86Sr)(t) ratios between 0.705136 and 0.706745. Values for ƐNd(t) in the granitic gneisses are in the range from 5.7 to 1.2, which correspond to Nd model ages of 2.01.7 Ga, indicating a role for Mesoproterozoic to Paleoproterozoic rocks in the generation of the granitic protoliths. The documented geochemical features indicate that the protoliths for the gneisses have a similar petrogenesis and magmatic source, which may reflect partial melting of thickened crust with the addition of small amounts of mantle-derived material. The Central Tianshan Block probably constitute part of an exterior orogen that developed along the margin of the Rodinian supercontinent during the Early Neoproterozoic and underwent a transition from subduction to syn-collision compression at 975911 Ma.
Subjects: Biology >> Biophysics >> Biochemistry & Molecular Biology submitted time 2016-05-12
Abstract: Toxic ribosome-inactivating proteins abolish cell viability by inhibiting protein synthesis. Ricin, a member of these lethal proteins, is a potential bioterrorism agent. Despite the grave challenge posed by these toxins to public health, post-exposure treatment for intoxication caused by these agents currently is unavailable. In this study, we report the identification of baicalin extracted from Chinese herbal medicine as a compound capable of inhibiting the activity of ricin. More importantly, post-exposure treatment with baicalin significantly increased the survival of mice poisoned by ricin. We determined the mechanism of action of baicalin by solving the crystal structure of its complex with the A chain of ricin (RTA) at 2.2 angstrom resolution, which revealed that baicalin interacts with two RTA molecules at a novel binding site by hydrogen bond networks and electrostatic force interactions, suggesting its role as molecular glue of the RTA. Further biochemical and biophysical analyses validated the amino acids directly involved in binding the inhibitor, which is consistent with the hypothesis that baicalin exerts its inhibitory effects by inducing RTA to form oligomers in solution, a mechanism that is distinctly different from previously reported inhibitors. This work offers promising leads for the development of therapeutics against ricin and probably other ribosome-inactivating proteins.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract: A simulation approach is developed to obtain the linear energy transfer (LET) spectrum of all secondary ions and predict single event upset (SEU) occurrence induced by neutron in memory devices. Neutron reaction channels, secondary ion species and energy ranges, and LET calculation method are introduced respectively. Experimental results of neutron induced SEU effects on static random access memory (SRAM) and programmable read only memory (EEPROM) are presented to confirm the validity of the simulation results.