Electromagnetic Force on an Aluminum Honeycomb Sandwich Panel Moving in a Magnetic Field.

This paper reports a method for calculating the electromagnetic force acting on an aluminum honeycomb sandwich panel moving in a magnetic field. This research is motivated by the non-contact electromagnetic detumbling technology for space non-cooperative targets. Past modeling of the electromagnetic forces and torques generally assumes that the target is homogeneous. However, aluminum honeycomb sandwich panels are extensively used in spacecraft structures to reduce weight without sacrificing structural strength and stiffness, which are so inhomogeneous and complicated that it is difficult to obtain the induced electromagnetic force even by numerical methods. An equivalent conductivity tensor of an aluminum honeycomb sandwich panel is proposed, which allows the aluminum honeycomb sandwich panel to be treated as a homogeneous structure when calculating the induced electromagnetic forces. The advantage of the equivalent conductivity tensor in the calculation of induced electromagnetic forces is verified by finite element simulations. The proposed method makes it possible to evaluate the electromagnetic force of a large aluminum honeycomb sandwich structure moving in a magnetic field.

A novel integrated time-resolved array avalanche photodiode detection system for nuclear resonant scattering measurements.

The nuclear resonant scattering (NRS) experiment requires photon-counting detectors with high time resolution, short dead time, large dynamic range, low noise, and large detection area. An 8-channel avalanche photodiode (APD) array detector system with high integrity, flexibility, and reliability has been developed to adapt to the demands of NRS experiments. The detector system mainly consists of four key parts: (i) an array-APD sensor, (ii) 8-channel integrated fast preamplifiers, (iii) the time-to-digital converter readout electronics, and (iv) a data acquisition system and EPICS support software. Remarkably, the system exhibits a time resolution of better than 500 ps and has a sufficiently low noise level, allowing for the lowest detection energy threshold of 4 keV. The performance of the new array-APD system as well as its real application in nuclear forward scattering (NFS) and nuclear resonant inelastic x-ray scattering (NRIXS) experiments was tested in two synchrotron facilities. With the new system, the NFS signal very close to the prompt electronic scattering signal can be extracted. Thanks to the customized EPICS-areaDetector-based control software, NRIXS spectra can be readily measured with time and energy information of the NRIXS signal stored in the raw data, which is promising for developing NRIXS data analysis in the time domain. The array-APD detector can be deployed for nuclear resonant scattering experiments at various synchrotron radiation facilities.

Spatial Metallomics Reveals Preferable Accumulation of Methylated Selenium in a Single Seed of the Hyperaccumulator Cardamine violifolia†.

Cardamine violifolia is a Se hyperaccumulator found in Enshi, China. In this study, spatial metallomics was applied to visualize the distribution and speciation of Se in a single seed of C. violifolia. It was found that Se reached 1729.89 ± 28.14 mg/kg and the main Se species were SeCys and SeMet in bulk seeds. Further in situ study on a single seed found that the methylated Se species located mostly in the episperm. This is the first visualized evidence of the in situ distribution of methylated Se species in the seeds of C. violifolia. In all, spatial metallomics finds a preferable accumulation of methylated Se species in the seed coat, which deepens the understanding of the tolerance of Se by C. violifolia. The protocol applied in this study may also be used for the understanding of the tolerance of heavy metals/metalloids in other hyperaccumulators.

Synthesis and Biological Evaluation of Novel Resveratrol-NSAID Derivatives as Anti-inflammatory Agents.

Long-term use of nonsteroidal antiinflammatory drugs (NSAIDs) may cause serious side effects such as gastric mucosal damage. Resveratrol, a naturally dietary polyphenol, exhibited anti-inflammatory activity and a protective effect against gastric mucosa damage induced by NSAIDs. In this regard, we synthesized a series of resveratrol-based NSAIDs derivatives and evaluated their anti-inflammatory activity against nitric oxide (NO) overproduction in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. We identified mono-substituted resveratrol-ibuprofen combination 21 as the most potent anti-inflammatory agent, which is more active than a physical mixture of ibuprofen and resveratrol, individual ibuprofen, or individual resveratrol. In addition, compound 21 exerted potent inhibitory effects on the LPS-induced expression of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß). Furthermore, compound 21 significantly increased the survival rate in an LPS-induced acute inflammatory model and produced markedly less gastric damage than ibuprofen. It was found that compound 21 may be a potent anti-inflammatory agent for the treatment of inflammation-related diseases.

Total synthesis and cytotoxic activities of longamide B, longamide B methyl ester, hanishin, and their analogues.

The marine alkaloids, longamide B (1), longamide B methyl ester (2), hanishin (3), and a series of non-naturally occurring analogues were synthesized in an efficient manner from inexpensive commercially available dl-aspartic acid dimethyl ester. The cytotoxicities of these natural products (1-3) and their analogues (9-15) were evaluated against human lung adenocarcinoma (A549) and human prostate cancer (PC3) cells. This is the first evaluation of the cytotoxicities of these alkaloids in these cancer cell lines and it revealed that analogue 15 had comparable cytotoxic activity to its natural parent compound, (±)-hanishin (3). This study provides useful information for further structural modification of these alkaloids in order to develop novel antitumor agents.

Coumarins with α-glucosidase and α-amylase inhibitory activities from the flower of Edgeworthia gardneri.

The flower of Edgeworthia gardneri is consumed in beverages in Tibet and has potential health benefits for diabetes. As a part of our continuous studies on dietary supplements for diabetes, two monomers, five dimers and one trimer of coumarins were isolated from the flowers of E. gardneri. One dimer was a new compound (1) and its structure was determined by spectroscopic methods, including multiple NMR techniques and mass spectrometry. The inhibitory activities of all coumarins against α-amylase and α-glucosidase were evaluated. Compound 4 displayed potent inhibitory effect on both α-amylase and α-glucosidase, with an IC50 of 90 and 86µg/mL, respectively. The IC50 of compound 3 against α-glucosidase was 18.7µg/mL, and its inhibition mode was noncompetitive. Based on the fluorescence analysis, the binding constant and the number of binding sites of compound 3 were calculated as 2.05×10(5) and 1.24, respectively. Furthermore, the interaction between compound 3 and α-glucosidase was a spontaneous process that was driven mainly by hydrophobic force. This study could facilitate the utilization of E gardneri as functional food ingredient.

α-Glucosidase Inhibition and Antihyperglycemic Activity of Phenolics from the Flowers of Edgeworthia gardneri.

The flowers of Edgeworthia gardneri are consumed as an herbal tea in Tibet with potential health benefits. To complement the current knowledge regarding the chemical composition and antihyperglycemic activity of the flower of E. gardneri, two new phenolics, gardnerol A and B (1 and 2), along with 19 known phenolics were isolated from the flower of E. gardneri. All isolates were evaluated for their inhibitory activity against α-glucosidase. Compound 5, identified as the major constituent of the flower of E. gardneri, showed a significant α-glucosidase inhibitory activity and acted as a competitive inhibitor. The oral administration of compound 5 at a dose of 300 mg/kg significantly reduced the postprandial blood glucose levels of normal and streptozotocin (STZ)-induced diabetic mice. Furthermore, compound 5 significantly decreased the fasting blood glucose levels in STZ-induced diabetic mice.

The measurement of differential EXAFS modulated by high pressure.

Differential EXAFS (DiffEXAFS) is able to detect subtle atomic perturbations in the local area of the absorbing atom. Here a new method of performing DiffEXAFS experiments under the modulation of high pressure has been developed. Periodic pressure was achieved in the gasket with the help of a dynamic diamond anvil cell, and the measurements were conducted in common energy-scanning mode. This technique has been utilized on ZnSe at 4.8 GPa. The present results have demonstrated a good agreement with the equation of state of ZnSe, and revealed sensitivity to atomic displacements of one order higher in magnitude than that of conventional EXAFS.

Developing VUV spectroscopy for protein folding and material luminescence on beamline 4B8 at the Beijing Synchrotron Radiation Facility.

The new 4B8 beamline provides UV-VUV light in the wavelength range from 360 to 120 nm. It uniquely enables two kinds of spectroscopy measurements: synchrotron radiation circular dichroism spectroscopy and VUV excited fluorescence spectroscopy. The former is mainly used in protein secondary structure studies, and the latter in VUV excited luminescent materials research. Remote access to fluorescence measurement has been realised and users can collect data online. Besides steady-state measurements, fluorescence lifetime measurements have been established using the time domain method, while a laser-induced temperature jump is under development for protein folding dynamics using circular dichroism as a probe.