| 1. |
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| 2. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 3. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 4. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Wang, Bo-Yao, et al.
(författare)
-
Nonlinear bandgap opening behavior of BN co-doped graphene
- 2016
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Ingår i: Carbon. - : Elsevier. - 0008-6223 .- 1873-3891. ; 107, s. 857-864
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Tidskriftsartikel (refereegranskat)abstract
- We have demonstrated a nonlinear behavior for the bandgap opening of doped graphene by controlling the concentration of B and N co-dopants. X-ray absorption and emission spectra reveal that the bandgap increases from 0 to 0.6 eV as the concentration of BN dopants is increased from 0 to 6%, while the bandgap closes when the doping concentration becomes 56%. This nonlinear behavior of bandgap opening of the BN-doped graphene depending on the BN concentrations is consistent with the valenceband photoemission spectroscopic measurements. The spatially resolved B, N and C K-edge scanning transmission x-ray microscopy and their x-ray absorption near- edge structure spectra all support the scenario of the development of h-BN-like domains at high concentrations of BN. Ab initio calculation, by taking into account of the strong correlation between the bandgap and the geometry/concentration of the dopant, has been performed with various BN-dopant nano-domains embedded in the graphene monolayer to verify the unique bandgap behavior. Based on the experimental measurements and ab initio calculation, we propose the progressive formation of a phase-separated zigzag-edged BN domain from BN quantum dots with increasing BN-dopant concentration to explain the extraordinary nonlinear behavior of bandgap opening of BN-doped graphene sheets. This study reveals a new way to engineer the bandgap of low-dimensional systems.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Wang, Fang, et al.
(författare)
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Emerging contaminants: A One Health perspective
- 2024
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Ingår i: Innovation. - 2666-6758. ; 5
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Forskningsöversikt (refereegranskat)abstract
- Environmental pollution is escalating due to rapid global development that often prioritizes human needs over planetary health. Despite global efforts to mitigate legacy pollutants, the continuous introduction of new substances remains a major threat to both people and the planet. In response, global initiatives are focusing on risk assessment and regulation of emerging contaminants, as demonstrated by the ongoing efforts to establish the UN's Intergovernmental Science-Policy Panel on Chemicals, Waste, and Pollution Prevention. This review identifies the sources and impacts of emerging contaminants on planetary health, emphasizing the importance of adopting a One Health approach. Strategies for monitoring and addressing these pollutants are discussed, underscoring the need for robust and socially equitable environmental policies at both regional and international levels. Urgent actions are needed to transition toward sustainable pollution management practices to safeguard our planet for future generations.
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| 14. |
- Zou, Yonggang, et al.
(författare)
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Rotational dynamics of confined C60 from near-infrared Raman studies under high pressure
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 106:52, s. 22135-22138
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Tidskriftsartikel (refereegranskat)abstract
- Peapods present a model system for studying the properties of dimensionally constrained crystal structures, whose dynamical properties are very important. We have recently studied the rotational dynamics of C60 molecules confined inside single walled carbon nanotube (SWNT) by analyzing the intermediate frequency mode lattice vibrations using near-infrared Raman spectroscopy. The rotation of C60 was tuned to a known state by applying high pressure, at which condition C60 first forms dimers at low pressure and then forms a single-chain, nonrotating, polymer structure at high pressure. In the latter state the molecules form chains with a 2-fold symmetry. We propose that the C60 molecules in SWNT exhibit an unusual type of ratcheted rotation due to the interaction between C60 and SWNT in the “hexagon orientation,” and the characteristic vibrations of ratcheted rotation becomes more obvious with decreasing temperature.
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| 15. |
- Liu, Dedi, et al.
(författare)
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In situ Raman and photoluminescence study on pressure-induced phase transition in C60 nanotubes
- 2012
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 43:6, s. 737-740
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Tidskriftsartikel (refereegranskat)abstract
- Single crystalline C60 nanotubes having face-centered-cubic structure with diameters in the nanometer range were synthesized by a solution method. In situ Raman and photoluminescence spectroscopy under high pressure were employed to study the structural stabilities and transitions of the pristine C60 nanotubes. A phase transition, probably because of the orientational ordering of C60 molecules, from face-centered-cubic structure to simple cubic structure occurred at the pressure between 1.46 and 2.26 GPa. At above 20.41 GPa, the Raman spectrum became very diffuse and lost its fine structure in all wavenumber regions, and only two broad and asymmetry peaks initially centered at 1469 and 1570cm-1 were observed, indicating an occurrence of amorphization. This amorphous phase remained to be reversible until 31.1 GPa, and it became irreversible to the ambient pressure after the pressure cycle of 34.3 GPa was applied.
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| 16. |
- Liu, Dedi, et al.
(författare)
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Pressure-induced phase transitions of C70 nanotubes
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society. - 1932-7447 .- 1932-7455. ; 115:18, s. 8918-8922
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Tidskriftsartikel (refereegranskat)abstract
- Single crystalline C70 nanotubes having a face-centered-cubic (fcc) structure with diameters on a nanometer scale were synthesized by a facile solution method. In situ high pressure Raman spectroscopy and X-ray diffraction have been employed to study the structural stability and phase transitions of the pristine sample. We show that the molecular orientation-related phase transition from the fcc structure to a rhombohedral structure occurs at about 1.5 GPa, which is 1 GPa higher than in bulk C70. Also, the C70 molecules themselves are more stable in the nanotubes than in bulk crystals, manifested by a partial amorphization at 20 GPa. The crystal structure of C70 nanotubes could partially return to the initial structure after a pressure cycle above 30.8 GPa, and the C70 molecules were intact up to 43 GPa. The bulk modulus of C70 nanotubes is measured to be 50 GPa, which is twice larger than that of bulk C70.
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| 17. |
- Qiu, Feng, et al.
(författare)
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A new IQ detection method for LLRF
- 2012
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 675, s. 139-143
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Tidskriftsartikel (refereegranskat)abstract
- Digital LLRF technology has been widely used in new generation particle accelerators. IF quadrature sampling is a common method for amplitude and phase detection. Many strategies, which obey the same rule of f(sample) = (M/N)f(IF) (M/N is a rational number), have been proposed to reduce the effects of spectrum aliasing. However, we found that M/N does not need to be a rational number according to Shannon's theorem. Therefore, we propose a new IQ detection method in this paper. This method is based on a special IIR filter which is derived from an RLC circuit. The unique characteristic of the method is that the value of f(IF) is independent of the value of, f(sample). We have set up an experimental platform to verify our method. A 122.88 MHz sampling clock is used to sample a 3 MHz IF signal. The DOS and PI control techniques are used to realize the closed-loop control. Results show that the stability of the system is within +/- 0.05% (peak to peak) for the amplitude, and with +/- 0.03 degrees (peak to peak) for the phase in 5 h. (C) 2012 Elsevier B.V. All rights reserved.
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| 18. |
- Wang, Lin, et al.
(författare)
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Synthesis and high pressure induced amorphization of C60 nanosheets
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:10, s. 103112-
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Tidskriftsartikel (refereegranskat)abstract
- C-60 nanosheets with thicknesses in the nanometer range were synthesized by a simple method. Compared to bulk C-60, the lattice of the nanosheets is expanded by about 0.4%. In situ Raman spectroscopy and energy-dispersive x-ray diffraction under high pressures have been employed to study the structure of the nanosheets. The studies indicate that the bulk modulus of the C-60 nanosheets is significantly larger than that of bulk C-60. The C-60 cages in nanosheets can persist at pressures over 30 GPa, 3 GPa higher than for bulk C-60. These results suggest that C-60 crystals in even small size will be a potential candidate of superhard materials.
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| 19. |
- Yao, Mingguang, et al.
(författare)
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Raman signature to identify the structural transition of single-wall carbon nanotubes under high pressure
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 78:20
-
Tidskriftsartikel (refereegranskat)abstract
- Raman spectra of single-walled carbon nanotubes (SWNTs) with diameters of 0.6–1.3 nm have been studied under high pressure. A “plateau” in the pressure dependence of the G-band frequencies was observed in all experiments, both with and without pressure transmission medium. Near the onset of the G-band plateau, the corresponding radial breathing mode (RBM) lines become very weak. A strong broadening of the full width at half maximum of the RBMs just before the onset of the G-band plateau suggests that a structural transition starts in the SWNTs. Raman spectra from SWNTs released from different pressures also indicate that a significant structural transition occurs during the G-band plateau process. Simulations of the structural changes and the corresponding Raman modes of a nanotube under compression show a behavior similar to the experimental observations. Based on the experimental results and the theoretical simulation, a detailed model is suggested for the structural transition of SWNTs, corresponding to the experimentally obtained Raman results in the high-pressure domain.
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| 20. |
- Yao, Xiangyu, et al.
(författare)
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A highly sensitive bead-based flow cytometric competitive binding assay to detect SARS-CoV-2 neutralizing antibody activity
- 2022
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Accurate detection of SARS-CoV-2 neutralizing antibody (nAb) is critical for assessing the immunity levels after virus infection or vaccination. As fast, cost-effective alternatives to viral infection-based assays, competitive binding (CB) assays were developed to quantitate nAb by monitoring the ability of sera to inhibit the binding of viral spike (S) protein to the angiotensin converting enzyme 2 (ACE2) receptor. Herein, we established a bead-based flow cytometric CB assay and tested the detection performance of six combination models, i.e. immobilized ACE2 and soluble Fc-tagged S1 subunit of S protein (iACE2/S1-Fc), immobilized ACE2 and soluble Fc-tagged receptor binding domain (RBD) of S protein (iACE2/RBD-Fc), immobilized S1 and soluble Fc-tagged ACE2 (iS1/ACE2-Fc), immobilized S1 and soluble His-tagged ACE2 (iS1/ACE2-His), immobilized RBD and soluble Fc-tagged ACE2 (iRBD/ACE2-Fc), and immobilized RBD and soluble His-tagged ACE2 (iRBD/ACE2-His). Using SARS-CoV-2 monoclonal antibodies and sera of convalescent COVID-19 patients and vaccinated subjects, the combination models iACE2/RBD-Fc, iACE2/S1-Fc and iS1/ACE2-His were identified to be able to specifically detect SARS-CoV-2 nAb, among which iACE2/RBD-Fc model showed the highest sensitivity, superior to a commercial SARS-CoV-2 surrogate virus neutralization test (sVNT) ELISA kit. Further studies demonstrated that the sensitivity and specificity of CB assays were affected by the tag of ACE2, type of spike and method of measuring binding rate between ACE2 and spike. Moreover, the iACE2/RBD-Fc model showed good performance in detecting kinetic development of nAb against both the prototype SARS-CoV-2 strain and an omicron variant of SARS-CoV-2 in people immunized by an inactivated SARS-CoV-2 vaccine, and the results of iACE2/RBD-Fc model are correlated well with those of live virus-based and pseudovirus-based neutralization tests, demonstrating the potential to be developed into a highly sensitive, specific, versatile and high-throughput method for detecting SARS-CoV-2 nAb in clinical practice.
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| 21. |
- Zhang, Ying, et al.
(författare)
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Capture of novel sp3 hybridized Z-BN by compressing boron nitride nanotubes with small diameter
- 2022
-
Ingår i: Diamond and related materials. - : Elsevier. - 0925-9635 .- 1879-0062. ; 130
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Tidskriftsartikel (refereegranskat)abstract
- Experimental synthesis of new sp3 hybridized carbon/boron nitride structures remains challenging despite that numerous sp3 structures have been proposed in theory. Here, we showed that compressed multi-walled boron nitride nanotubes (MWBNNTs) and boron nitride peapods (C60@BNNTs) with small diameters could transform into a new sp3 hybridized boron nitride allotrope (Z-BN). This strategy is considered from the topological transition point of view in boron nitride nanotubes upon compression. Due to the increased curvature in compressed small-diameter MWBNNTs, the uncommon 4- and 8-membered rings in Z-BN could be more favorably formed. And the irreversible tube collapse is proved to be a critical factor for the capture of the formed Z-BN, because of the competition between the resilience of tube before collapse and the stress limitation for the lattice stabilization of Z-BN upon decompression. In this case, Z-BN starts to form above 19.0 GPa, which is fully reversible below 45 GPa and finally becomes quenchable at 93.5 GPa. This collapse-induced capture of the high-pressure phase could also be extended to other tubular materials for quenching novel sp3 structures.
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| 22. |
- Zou, Yonggang, et al.
(författare)
-
Raman spectroscopy study of carbon nanotube peapods excited by near-IR laser under high pressure
- 2007
-
Ingår i: Physical Review B. - 0163-1829. ; 76:19, s. 195417-
-
Tidskriftsartikel (refereegranskat)abstract
- A resonant Raman spectroscopy study has been carried out under high pressure, using a diamond anvil cell,on carbon nanotube peapods (C60@SWNT) synthesized in high yield in our laboratory. The Raman signal wasexcited by a near IR laser (830 nm) to avoid photopolymerization of C60 and thus obtain the intrinsic vibrationalinformation on the C60 molecules in the nanotubes. It is found that the surrounding tubes create aneffective pressure on the encapsulated C60 due to tube-fullerene interactions, resulting in a shift of the intrinsicAg(2) vibrational mode to 1474 cm−1 at ambient pressure. High pressure Raman spectroscopy indicates that(C60)2 dimers form near 1 GPa, and that a further polymerization of C60 occurs near 23 GPa, creating linearchains of covalently linked C60 molecules in the tubes.
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| 23. |
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| 24. |
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| 25. |
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| 26. |
- Falth, JF, et al.
(författare)
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Influence of dislocation density on photoluminescence intensity of GaN
- 2005
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 278:01-Apr, s. 406-410
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of dislocation density on photoluminescence intensity is investigated experimentally and compared to a model. GaN samples were grown by molecular beam epitaxy and metal-organic chemical vapour deposition. Different growth parameters and thicknesses of the layers resulted in different dislocation densities. The threading dislocation density, measured by atomic force microscopy, scanning electron microscopy and X-ray diffraction, covered a range from 5 x 10(8) to 3 x 10(10) cm(-2). Carrier concentration was measured by capacitance-voltage-, and Hall effect measurements and photoluminescence at 2 K was recorded. A model which accounts for the photoluminescence intensity as a function of dislocation density and carrier concentration in GaN is developed. The model shows good agreement with experimental results for typical GaN dislocation densities, 5 x 10(8)-1 x 10(10) cm(-2), and carrier concentrations 4 x 10(16)-1 x 10(18) cm(-3). ©, 2005 Elsevier B.V. All rights reserved.
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| 27. |
- He, Wang, et al.
(författare)
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Implications of Incident Power Density Limits on Power and EIRP Levels of 5G Millimeter-Wave User Equipment
- 2020
-
Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 8, s. 148214-148225
-
Tidskriftsartikel (refereegranskat)abstract
- User equipment (UE) is required to comply with the relevant radio frequency (RF) electromagnetic field (EMF) exposure limits, which are of relevance to establish the maximum permissible transmitted power and the maximum equivalent isotropically radiated power (EIRP). Recently, international RF EMF exposure guidelines, such as those published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) as well as by the IEEE, have been updated. In this paper, the implications of the revised incident power density limits are investigated in terms of maximum permissible transmitted power and the maximum EIRP for devices operating in close proximity of the user. A similar analysis is conducted according to the US Federal Communications Commission (FCC) regulation on RF exposure. EMF compliance of UE is studied by means of numerical modelling of patch antenna arrays of different array sizes taking into consideration of possible beam-steering operations, at frequencies ranging from 10 GHz to 100 GHz. The results are compared with the 3rd Generation Partnership Project (3GPP) requirements on the total radiated power (TRP) and EIRP levels. The present implications of the incident power density limits for 5G millimeter-wave UE will give valuable insights to mobile equipment manufacturers, network operators, and standardization bodies.
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| 28. |
- Hou, Yuanyuan, et al.
(författare)
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Comparative study of pressure-induced polymerization of C60 nanorods and single crystals
- 2007
-
Ingår i: Journal of Physics Condensed Matter. - Bristol : Institute of Physics. - 0953-8984 .- 1361-648X. ; 19:42, s. 425207-
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report a comparative study of pressure-induced polymerization in C60 nanorods and bulk single crystals, treated simultaneously under various pressures and temperatures in the same experiment. For both materials, orthorhombic, tetragonal and rhombohedral phases have been produced under high pressure and high temperature. The structures have been identified and compared between the two sample types by Raman and photoluminescence spectroscopy. There are differences between the Raman and photoluminescence spectra from the two types of materials for all polymeric phases, but especially for the tetragonal phase. From the comparison between nanorods and bulk samples, we tentatively assign photoluminescence peaks for various polymeric phases.
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| 29. |
- Klionsky, Daniel J., et al.
(författare)
-
Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes
- 2008
-
Ingår i: Autophagy. - : Landes Bioscience. - 1554-8627 .- 1554-8635. ; 4:2, s. 151-175
-
Forskningsöversikt (refereegranskat)abstract
- Research in autophagy continues to accelerate,1 and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.2,3 There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.
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| 30. |
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| 31. |
- Li, Xin, et al.
(författare)
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Effects of domain size on x-ray absorption spectra of boron nitride doped graphenes
- 2016
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 109:8
-
Tidskriftsartikel (refereegranskat)abstract
- Doping is an efficient way to open the zero band gap of graphene. The control of the dopant domain size allows us to tailor the electronic structure and the properties of the graphene. We have studied the electronic structure of boron nitride doped graphenes with different domain sizes by simulating their near-edge X-ray absorption fine structure (NEXAFS) spectra at the N K-edge. Six different doping configurations (five quantum dot type and one phase-separated zigzag-edged type) were chosen, and N K-edge NEXAFS spectra were calculated with large truncated cluster models by using the density functional theory with hybrid functional and the equivalent core hole approximation. The opening of the band gap as a function of the domain size is revealed. We found that nitrogens in the dopant boundary contribute a weaker, red-shifted pi* peak in the spectra as compared to those in the dopant domain center. The shift is related to the fact that these interfacial nitrogens dominate the lowest conduction band of the system. Upon increasing the domain size, the ratio of interfacial atom decreases, which leads to a blue shift of the pi* peak in the total NEXAFS spectra. The spectral evolution agrees well with experiments measured at different BN-dopant concentrations and approaches to that of a pristine h-BN sheet.
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| 32. |
- Liu, Dedi, et al.
(författare)
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Synthesis and solid-state studies of self-assembled C60 microtubes
- 2011
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Ingår i: Diamond and Related Materials, vol. 20 issue 2. - : Elsevier BV. ; , s. 178-182
-
Konferensbidrag (refereegranskat)abstract
- C60 microtubes were fabricated by a modified solution evaporation method, evaporating a solution of C60 in toluene in an atmosphere of m-xylene at room temperature. The C60 microtubes have outer diameters ranging from 2 to 8 μm. IR spectra, TG analysis and X-ray diffraction showed a solvated structure for the as-grown C60 microtubes. Through a gentle heat-treatment in vacuum, pure C60 microtubes with single crystalline fcc structure were obtained after the elimination of solvents. It is suggested that the C60 microtubes form through self-assembly from several individual C60 nanorods.
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| 33. |
- Liu, Haifeng, et al.
(författare)
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Laser diagnostics and chemical kinetic analysis of PAHs and soot in co-flow partially premixed flames using diesel surrogate and oxygenated additives of n-butanol and DMF
- 2018
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Ingår i: Combustion and Flame. - : Elsevier BV. - 0010-2180. ; 188, s. 129-141
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Tidskriftsartikel (refereegranskat)abstract
- Effects of oxygenated fuels on soot reduction strongly depend on the base fuel. Interesting candidates from oxygenated fuels in this respect include both n-butanol and 2,5-dimethylfuran (DMF), because they have already been used in diesel engines recently. However, information is rather limited on n-butanol and DMF added into a diesel fuel surrogate in fundamental flames to investigate the mechanism of soot reduction. In the current work, both n-butanol and DMF was successively added into diesel surrogate (80% n-heptane and 20% toluene in volume, named as T20) in co-flow partially premixed flames. The effects of different oxygenated structures on polycyclic aromatic hydrocarbons (PAHs) and soot were investigated at the same oxygen weight fractions of 4% and the same volume fractions of 20%. The diagnostics on PAHs, soot volume fractions and soot sizes were conducted by using both laser-induced fluorescence (LIF) and two-color laser-induced incandescence (2C-LII). A combined detailed kinetic model (n-heptane/toluene/butanols/DMF/PAHs) has been obtained in order to clarify the chemical effects of the different oxygenated fuels on PAHs formation. Results show that the reduced toluene content due to the addition of oxygenated fuels is the dominant factor for the reduction of soot, as compared with the base fuel of T20. The oxygenated structure of n-butanol has a higher ability to reduce PAHs and soot as compared with the addition of DMF. This is due to the fact that the consumption of DMF leads to much formation of C5H5 which enhances the formation of PAHs and subsequent soot. However, the formation of PAHs can be inhibited remarkably as blending n-butanol because only small hydrocarbons like C2H2 and C3H3 etc. are formed. The formation rate of A4 is more similar to that of soot in comparison with the smaller ring aromatics. For the size of soot particles, the distribution range is shrunk from 19–70 nm for T20 to 20–40 nm for the addition of oxygenated fuels. As compared to the effects of oxygenated structures, DMF20 presents a little wider distribution on soot sizes than that of B16.8. Some larger soot particles are detected in DMF20 flame but cannot be found in B20 flame.
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| 34. |
- Qiu, Bo, et al.
(författare)
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Enhanced gut microbiota delivery of a model probiotic (Faecalibacterium prausnitzii) : Layer-by-layer encapsulation using riboflavin-conjugated sodium alginate and glycol chitosan
- 2024
-
Ingår i: Food Hydrocolloids. - : Elsevier. - 0268-005X .- 1873-7137. ; 154
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Tidskriftsartikel (refereegranskat)abstract
- Faecalibacterium prausnitzii (F. prausnitzii) exhibits a variety of biological functions that make it suitable for use as a next-generation probiotic. However, its high sensitivity to oxygen and digestive fluids currently limits its application. Riboflavin is known to support the growth of F. prausnitzii in oxygen environments, but it is important that it is in close proximity to the probiotics. Layer-by-layer assembly can be used to form protective coatings around probiotics, which can protect them from adverse environmental conditions. Moreover, riboflavin can be conjugated to these coatings, thereby increasing its efficacy by bringing it close to probiotic surfaces. In this study, we therefore evaluated the potential of electrostatic layer-by-layer assembly to protect F. prausnitzii by coating them with riboflavin-alginate and glycol-chitosan layers. Initially, we showed that riboflavin could be successfully conjugated to alginate, with a grafting ratio of around 4.35%. Then, the layer-by-layer method was used to coat F. prausnitzii using cationic glycol chitosan and anionic riboflavin-alginate. The coating formed was found to have a thickness of approximately 18.5 nm. Encapsulation did not adversely affect the growth of F. prausnitzii, but it significantly enhanced its resistance to oxygen and digestive fluids. The encapsulated probiotic was shown to have enhanced mucoadhesive properties using an in vitro intestinal monolayer model. Furthermore, the encapsulated probiotics colonized the colons of rats for longer than nonencapsulated ones. These results show that coating F. prausnitzii with riboflavin-rich biopolymer layers improves its resistance to oxygen and digestive fluids, and enhances its mucoadhesion and colonization properties, which should enhance its potential as an orally administered probiotic.
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| 35. |
- Sha, Jingeng, et al.
(författare)
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Stratigraphy of the Triassic-Jurassic Boundary Successions of the Southern Margin of the Junggar Basin, Northwestern China
- 2011
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Ingår i: Acta Geologica Sinica. - : Wiley. - 1000-9515. ; 85:2, s. 421-436
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Tidskriftsartikel (refereegranskat)abstract
- The Triassic-Jurassic (Tr-J) boundary marks a major extinction event, which (similar to 200 Ma) resulted in global extinctions of fauna and flora both in the marine and terrestrial realms. There prevail great challenges in determining the exact location of the terrestrial Tr-J boundary, because of endemism of. : and the scarcity of fossils in terrestrial settings leading to difficulties in linking marine and terrestrial sedimentary successions. Investigation based on palynology and bivalves has been carried out over a 1113 m thick section, which is subdivided into 132 beds, along the Haojiagou valley on the southern margin of the Junggar Basin of the northern Xinjiang, northwestern China. The terrestrial Lower Jurassic is conformably resting on the Upper Triassic strata. The Upper Triassic covers the Huangshanjie Formation overlaid by the Haojiagou Formation, while the Lower Jurassic comprises the Badaowan Formation followed by the Sangonghe Formation. Fifty six pollen and spore and one algal on were identified from the sediments. Based on the key-species and abundance of spores and pollen, three zones were erected: the Late Triassic (Rhaetian) Aratrisporites-Alisporites Assemblage, the Early Jurassic (Hettangian) Perinopollenites-Pinuspollenites Assemblage, and the Sinemurian Perinopollenites-Cycadopites Assemblage. The Tr-J boundary is placed between bed 44 and 45 coincident with the boundary between the Haojiagou and Badaowan formations. Beds with Ferganoconcha (?), Unio-Ferganoconcha id Waagenoperna-Yananoconcha bivalve assemblages are recognized. The Ferganoconcha (?) bed is limited to the upper Haojiagou Formation, Unio-Ferganoconcha and Waagenoperna-Yananoconcha assemblages are present in the middle and upper members of the Badaowan Formation. The sedimentary succession is interpreted as terrestrial with two mainly lake deposit intervals within Haojiagou and Badaowan formations, yielding fresh water algae and bivalves. However, the presence of brackish water algae Tasmanites and the marine-littoral facies bivalve Waagenoperna from the Badaowan Formation indicate that the Junggar Basin was influenced by sea water caused by transgressions from the northern Tethys, during the Sinemurian.
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| 36. |
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| 37. |
- Wang, Xiangjian, et al.
(författare)
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Multifunctionality in (K,Na)NbO3-based ceramic near polymorphic phase boundary
- 2021
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 130:6
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Tidskriftsartikel (refereegranskat)abstract
- The 0.95K0.42Na0.58Nb0.96Sb0.04O3–0.02BaZrO3–0.03Bi0.5K0.5HfO3 ceramic was fabricated via a conventional solid-state reaction. This ceramic exhibits the diffuse polymorphic phase boundary (PPB) near room temperature. The dielectric, ferroelectric, electromechanical, electrocaloric, and dielectric energy storage properties were studied systemically. The normalized large signal d33* values are approximately 400–600 pm/V at measured temperatures and electric fields, which are larger than or comparable with the values reported in other lead-free compositions. The electrocaloric strength is enhanced at the broad region of PPB provided by the indirect and direct measurements. At low field of 30 kV/cm, the dielectric energy storage is ∼0.12–018 J/cm3 at relative broad temperature range due to the diffuse nature of polymorphic phase boundary. Theoretical simulations reveal that multi-element dopants, such as Sb5+, Hf4+, Zr4+, and Bi3+ ions, could induce the breaking of local structure symmetry in the orthorhombic phase to form the PPB. In addition, the charge distribution may also break the long-range ferroelectric order through the analysis of Bader charge. Our study suggests that the K0.5Na0.5NbO3-based ceramic exhibits improved performance and good thermal stability in piezoelectric, electrocaloric, and dielectric energy storage characteristics in terms of the design of multi-element dopants to form the PPB and it will benefit the promising applications in electronic devices.
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| 38. |
- Wen, Wanqing, et al.
(författare)
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Genome-wide association studies in East Asians identify new loci for waist-hip ratio and waist circumference
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Sixty genetic loci associated with abdominal obesity, measured by waist circumference (WC) and waist-hip ratio (WHR), have been previously identified, primarily from studies conducted in Europeanancestry populations. We conducted a meta-analysis of associations of abdominal obesity with approximately 2.5 million single nucleotide polymorphisms (SNPs) among 53,052 (for WC) and 48,312 (for WHR) individuals of Asian descent, and replicated 33 selected SNPs among 3,762 to 17,110 additional individuals. We identified four novel loci near the EFEMP1, ADAMTSL3, CNPY2, and GNAS genes that were associated with WC after adjustment for body mass index (BMI); two loci near the NID2 and HLA-DRB5 genes associated with WHR after adjustment for BMI, and three loci near the CEP120, TSC22D2, and SLC22A2 genes associated with WC without adjustment for BMI. Functional enrichment analyses revealed enrichment of corticotropin-releasing hormone signaling, GNRH signaling, and/or CDK5 signaling pathways for those newly-identified loci. Our study provides additional insight on genetic contribution to abdominal obesity.
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