分类: 化学 >> 物理化学 提交时间: 2017-11-05 合作期刊: 《结构化学》
摘要: Two new coordination polymers, namely, {[Cd1.5(bc)2(HL)].H2O}2n (1) and [Mn(ip)(H2L)(H2O)]n (2) (H2L = 3-(1H-pyrazol-4-yl)-5-(pyridin-2-yl)-1,2,4-triazole, Hbc = benzoic acid, H2ip = isophthalic acid) were constructed by solvothermal reaction. The compounds were characterized by elemental analysis, FT-IR spectroscopy, and single-crystal X-ray diffraction. Compound 1 displays a two-dimensional plane structure consisting of [Cd3(bc)2(HL)] subunits. Compound 2 possesses a one-dimensional chain structure and is further extended into a 3-D supramolecular architecture via hydrogen bonds. Moreover, photoluminescence studies showed compound 1 exhibits luminescent emissions with emission maxima at 375 nm. Magnetic susceptibility measurements of 2 indicate that domain antiferromagnetic interactions exist between Mn(II) ions. In addition, thermogravimetric properties of 1 and 2 were also measured.
分类: 化学 >> 物理化学 提交时间: 2017-11-05 合作期刊: 《结构化学》
摘要: 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.
分类: 化学 >> 物理化学 提交时间: 2017-11-05 合作期刊: 《结构化学》
摘要: Two new zinc(II) coordination polymers, [Zn(ph)(H2L)·H2O]2n (1) and [Zn(ip)(H2L)(H2O)]n (2) (H2ph = phthalic acid, H2ip = isophthalic acid, H2L = 3-(1H-pyrazol-4-yl)-5-(pyridin-2-yl)-1,2,4-triazole), have been successfully synthesized via hydrothermal reaction. It has been structurally characterized by X-ray single-crystal analysis, IR spectra, fluorescence spectroscopy and thermogravimetry analysis. The single-crystal X-ray diffraction studies reveal that compounds 1 and 2 both exhibit 1D chain structures, and assemble into 2D and 3D supermolecules through hydrogen bonds or π-π interactions. Moreover, the thermal stability and luminescent properties of compounds 1 and 2 were also studied.
分类: 核科学技术 >> 粒子加速器 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: The absolute dose difference of the iso-center position at different times was used to evaluate the stability of medical linear accelerator (LINAC). In order to eliminate the drawback of point dose without statistical significance and to investigate the output stability of segment with small weight related to intensity-modulated radiotherapy (IMRT), a modified method of evaluating the stability of LINAC was proposed based on planar dose combined with gamma method. With a commercial available two-dimensional ionization chamber, a set of planar doses with dose gradient from 2 cGy to 100 cGy were obtained. Then the gamma method was adopted to analyze the dose difference between the reference data and the evaluated data at each dose level. The results showed that the improved method based on planar dose for analyzing the output stability of the medical LINAC was feasible and efficient, and suggested that the reverse optimization should be aborted in clinical when the segment weight related to IMRT was under 10 MU.
分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2024-02-01 合作期刊: 《Research in Astronomy and Astrophysics》
摘要: The thermal gradient is an important factor that causes degradation to the image quality of telescopes. In order to ensure the accurate alignment of the primary focus unit and the primary mirror, the hexapod platform (as a corrector) is investigated in this paper. First, a ground-based telescope with 2.5 m aperture and 3.5 deg field of view is described. The telescope is under construction, and it is expected to be finished in 2023. Second, the hexapod platform with flexure hinges utilized to adjust the primary focus unit is proposed, which is applied as a corrector. Then, the inverse kinematics of the platform is established and an open-loop control system is built based on it. Finally, the cryogenic performance test for the hexapod platform is performed. The experimental results show that the resolution and repeatability of the translation for the hexapod platform can be achieved at the micrometer level. The resolution and repeatability of the rotation can be achieved at the arc-second level. Therefore, the cryogenic performance of the hexapod platform can meet the optical imaging requirements of the wide-field ground-based telescope. The kinematic analysis and cryogenic performance tests in the paper provide a technical reference for the precise alignment of the primary focus unit and the primary mirror, which can improve the imaging quality of the telescope.
分类: 物理学 >> 核物理学 提交时间: 2022-01-21 合作期刊: 《Nuclear Science and Techniques》
摘要: Configurational information entropy (CIE) theory was employed to determine the neutron skin thickness of neutron-rich calcium isotopes. The nuclear density distributions and fragment cross-sections in 350 MeV/u 40-60Ca + 9Be projectile fragmentation reactions were calculated using a modified statistical abrasion-ablation model. CIE quantities were determined from the nuclear density, isotopic, mass, and charge distributions. The linear correlations between the CIE determined using the isotopic, mass, and charge distributions and the neutron skin thickness of the projectile nucleus show that CIE provides new methods to extract the neutron skin thickness of neutron-rich nuclei.
分类: 物理学 >> 核物理学 提交时间: 2021-12-31
摘要: Configurational information entropy (CIE) theory was employed to determine the neutron skin thickness of neutron-rich calcium isotopes. The nuclear density distributions and fragment cross-sections in 350 MeV/u 40060Ca + 9Be projectile fragmentation reactions were calculated using a modified statistical abrasion-ablation model. CIE quantities were determined from the nuclear density, isotopic, mass, and charge distributions. The linear correlations between the CIE determined using the isotopic, mass, and charge distributions and the neutron skin thickness of the projectile nucleus show that CIE provides new methods to extract the neutron skin thickness of neutron-rich nuclei.
分类: 核科学技术 >> 裂变堆工程技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Molecular dynamics method is used to investigate the displacement cascades in Ni-Mo binary alloy. Effects of the irradiation temperature, energy of the primary knock-on atoms and concentration of solute Mo atoms are taken into consideration on radiation damage to the Ni-Mo alloy. It is found that Mo atoms reduce production of the Frenkel pairs at 100 K, while they enhance defect production at 300 K and 600 K. Size of the largest defect clusters decreases with increasing concentrations of Mo atoms (CMo) at 100 K, but it increases with CMo at 300 K and 600 K. Most of the point defects get clustered in cascades leaving only a few vacancies and interstitials isolated.
分类: 化学 >> 物理化学 提交时间: 2017-11-05 合作期刊: 《结构化学》
摘要: A new iodiplumbate/organic hybrid constructed from asymmetric viologen and polyiodides, (PBPY-H2)2[PbI4(I3)2] (1, PBPY = N-(propionate)-4,4΄-bipyridinium), has been synthesized via solvothermal reaction and structurally determined by X-ray diffraction method. Compound 1 crystallizes in monoclinic system, space group P21/c with Mr = 1936.72, a = 11.622(2), b = 14.839(3), c = 13.372(2) Å, β = 109.447(3)°, V = 2174.6(7) Å3, Z = 2, Dc = 2.958 g/cm3, F(000) = 1712, μ(MoKα) = 11.011 mm–1, the final R = 0.0389 and wR = 0.0854 for 3866 observed reflections with I > 2σ(I). [PbI4(I3)2]4- mononuclear cluster of 1 features a seldom example of coordinated I3- donors for the lead center. Intermolecular hydrogen bonds between [PbI4(I3)2]4- clusters and (PBPY-H)24+ dimmers contribute to the formation of a 2-D layer. Its absorption spectrum was investigated, and lower energy band gap of 1.42 eV was explained by DFT calculation. Interestingly, 1 exhibits photocatalytic activity for the degradation of rhodamine B.
分类: 生物学 >> 生物工程 提交时间: 2024-03-05
摘要: Single-molecule discrimination among amino acids is crucial to the realization of next-generation protein sequencing. Owing to the heterogeneous charge and subtle volume difference of underivatized amino acids, it remains a challenge for single-molecule techniques to recognize each of them. Here, we report the direct detection of twenty proteinogenic amino acids using a copper(II)-functionalized MspA nanopore. The binding sites for copper(II) ion are constructed by introducing histidine mutation (N91H) to M2MspA protein. With copper ion binding to histidine residues, amino acids can reversibly coordinate the copper-histidine complex, generating well-defined current signals. Using this strategy, all twenty amino acids can be detected. Assisted by a machine learning algorithm, we can identify 100% of signals with 70.2% accuracy or 60% of signals with 93.4% accuracy in the validation set. In successively addition experiment, each amino acid in a mixture of 10 amino acids can be identified precisely. Furthermore, we use carboxypeptidase A1 to partly release the C-terminal amino acids of peptides with different lengths (9, 10 and 22 residues). The hydrolysates of peptides can be identified and distinguished. These results demonstrate the feasibility of this system for amino acids detection and peptide identification, shedding new lights on the development of single-molecule protein sequencing.
分类: 核科学技术 >> 粒子加速器 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Beamline BL16B1 at Shanghai Synchrotron Radiation Facility (SSRF) is dedicated to small angle X-ray scattering (SAXS) study. It aims at probing microstructure and dynamic processes of polymers, nanomaterials, mesoporous materials, colloids, liquid crystals, metal materials, etc. At present, SAXS, wide angle X-ray scattering (WAXS), simultaneous SAXS/WAXS, grazing incident SAXS, and anomalous SAXS techniques are available. The sample-to-detector distance is adjustable from 0.2 m to 5 m. For conventional SAXS, the practicable q-range is from 0.033.6 nm-1 at incident X-ray of 10 keV. A continuous q-region of 0.0633 nm-1 can be achieved in simultaneous SAXS/WAXS mode. Time-resolved SAXS measurements in sub-second level can be performed. Detailed descriptions about status, performance and application of the SAXS beamline are given in this paper.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-12
摘要: The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway has been identified as an important pathway in renal cell carcinoma (RCC). We have reported a nonsense mutation in PIK3R1, which encodes the regulatory subunit of PI3K, in a metastatic RCC (mRCC), while the mutation was absent in the corresponding primary RCC (pRCC). To identify the function of PIK3R1 in RCC, we examined its expression in normal kidney, pRCC and mRCC by immunohistochemistry and real-time polymerase chain reaction. The expression of PIK3R1 significantly decreased in pRCC and was further reduced in mRCC compared with normal tissue. Besides, its expression levels were negatively correlated with T-category of tumor stage. Additionally, 786-O and A-704 cells with PIK3R1 depletion introduced by CRISPR/Cas9 system displayed enhanced proliferation, migration and epithelial-mesenchymal transition (EMT), and acquired a stem-like phenotype. Moreover, the PIK3R1 depletion promoted the phosphorylation of AKT in the cells. The knockdown of AKT by shRNA reduced p-GSK3 beta and CTNNB1 expression in the cells, while the depletion of CTNNB1 impaired stem-like phenotype of the cells. Overall, PIK3R1 down-regulation in RCC promotes propagation, migration, EMT and stem-like phenotype in renal cancer cells through the AKT/GSK3 beta/CTNNB1 pathway, and may contribute to progression and metastasis of RCC.
分类: 生物学 >> 生态学 提交时间: 2017-11-17
摘要: Background: The adapter proteins Appl1 (adaptor protein containing pleckstrin homology domain, phosphotyrosine domain, and leucine zipper motif 1) and Appl2 are highly homologous and involved in several signaling pathways. While previous studies have shown that Appl1 plays a pivotal role in adiponectin signaling and insulin secretion, the physiological functions of Appl2 are largely unknown. Results: In the present study, the role of Appl2 in sepsis shock was investigated by using Appl2 knockout (KO) mice. When challenged with lipopolysaccharides (LPS), Appl2 KO mice exhibited more severe symptoms of endotoxin shock, accompanied by increased production of proinflammatory cytokines. In comparison with the wild-type control, deletion of Appl2 led to higher levels of TNF-alpha and IL-1 beta in primary macrophages. In addition, phosphorylation of Akt and its downstream effector NF-kappa B was significantly enhanced. By co-immunoprecipitation, we found that Appl2 and Appl1 interacted with each other and formed a complex with PI3K regulatory subunit p85 alpha, which is an upstream regulator of Akt. Consistent with these results, deletion of Appl1 in macrophages exhibited characteristics of reduced Akt activation and decreased the production of TNF alpha and IL-1 beta when challenged by LPS. Conclusions: Results of the present study demonstrated that Appl2 is a critical negative regulator of innate immune response via inhibition of PI3K/Akt/NF-kappa B signaling pathway by forming a complex with Appl1 and PI3K.Conclusions: Results of the present study demonstrated that Appl2 is a critical negative regulator of innate immune response via inhibition of PI3K/Akt/NF-kappa B signaling pathway by forming a complex with Appl1 and PI3K.