| 1. |
- Xiong, Ya, et al.
(författare)
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Crystal structures and supramolecular assembly of 1 : 2 piperazine with o- and p-nitrophenol
- 2002
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Ingår i: Journal of Chemical Crystallography. - 1074-1542. ; 32:8, s. 219-225
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Tidskriftsartikel (refereegranskat)abstract
- 1:2 Cocrystals of piperazine (PPN) with o- and p-nitrophenol (oNPH and pNPH) were obtained from aqueous solution. The co-crystal structure of PPN, 2pNPH, and 2H(2)O is triclinic space group P (1) over bar: a = 6.401(1) Angstrom, b = 6.7515(1) Angstrom, c = 11.219(1) Angstrom, alpha = 100.37(1)degrees, beta = 97.10(1)degrees, gamma = 99.99(1)degrees,V= 465.5(1) Angstrom(3), Z = 2. Refinement led to a final conventional R value of 0.0365 for 2081 reflections. PPN, 2oNPH, and 2H(2)O cocrystallize in the monoclinic space group P2(1) : a = 7.753(1) Angstrom, b = 10.888(2) Angstrom, c = 11.378(2) Angstrom, beta = 92.89(1)degrees, V = 953.1(3) Angstrom(3), Z = 2. Refinement led to a final conventional R value of 0.0347 for 1978 reflections. It was found in both cocrystals that the hydroxyl H-atom of pNPH and oNPH was transferred to a N-atom of PPN, forming new ionic complexes PPNH22+.2(oNP(-)) and PPNH22+.2(pNP(-)), respectively.
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| 2. |
- Wang, Nan, et al.
(författare)
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Highly thermal conductive and electrically insulated graphene based thermal interface material with long-term reliability
- 2019
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Ingår i: Proceedings - Electronic Components and Technology Conference. - 0569-5503. ; 2019-May, s. 1564-1568
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Konferensbidrag (refereegranskat)abstract
- High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. The conventional TIMs that are widely used in the microelectronic industry today are experiencing more and more stress due to their limited thermal performance and poor reliability. Composed by particle laden polymer matrix, thermal conductivity (K) of conventional TIMs is generally limited to 5 W/mK, and such values can be even lower for electrically insulated TIMs. Conventional TIMs also suffer from severe pump-out and dry-out failures, which brought great threat to the performance and lifetime of the electronic devices. Here, we solve these problems by applying a novel highly thermal conductive, electrically insulated and reliable graphene based TIMs (I-GTs). Composed by vertical graphene structures, I-GTs provide a continuous heat pathway from top to bottom, which enables superfast heat dissipation at through-plane direction. The highest bulk through-plane thermal conductivity of the conductive body can reach up to 1000 W/mK, which is orders of magnitude higher than conventional TIMs, and even outperforms the pure indium TIMs by over ten times. The highly flexible and foldable nature of I-GT enables at least 100% compressibility upon small applied pressures. As excellent gap fillers, I-GT can provide complete physical contact between two surfaces and thereby minimize the contact resistance to heat flow. The measured minimum thermal resistance for I-GTs reaches about 30 Kmm2/W. Such values are significantly higher than the randomly dispersed composites presented above. To ensure fully electrical insulation, a smooth and soft adhesive layer with a thickness of few microns was coated on the surface of I-GT. The breakdown voltage of I-GT reaches up to 950 V. Thermal cycling test shows the highly stable nature of I-GT. The good compressibility and elasticity of I-GT ensures continued proper TIM contact with substrates, which counteracts the effect of internal stress induced by the mismatch of coefficient of thermal expansion (CTE) during temperature cycling. In addition, the I-GTs have the advantages of low density and good maintainability. The resulting I-GTs thus opens new opportunities for addressing large heat dissipation issues for form-factor driven electronics and other high power driven systems.
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| 3. |
- Liu, Zhengfa, et al.
(författare)
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Mixed Event-Frame Vision System for Daytime Preceding Vehicle Taillight Signal Measurement Using Event-Based Neuromorphic Vision Sensor
- 2022
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Ingår i: Journal of Advanced Transportation. - : Hindawi Limited. - 0197-6729 .- 2042-3195. ; 2022
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Tidskriftsartikel (refereegranskat)abstract
- An important aspect of the perception system for intelligent vehicles is the detection and signal measurement of vehicle taillights. In this work, we present a novel vision-based measurement (VBM) system, using an event-based neuromorphic vision sensor, which is able to detect and measure the vehicle taillight signal robustly. To the best of our knowledge, it is for the first time the neuromorphic vision sensor is paid attention to for utilizing in the field of vehicle taillight signal measurement. The event-based neuromorphic vision sensor is a bioinspired sensor that records pixel-level intensity changes, called events, as well as the whole picture of the scene. The events naturally respond to illumination changes (such as the ON and OFF state of taillights) in the scene with very low latency. Moreover, the property of a higher dynamic range increases the sensor sensitivity and performance in poor lighting conditions. In this paper, we consider an event-driven solution to measure vehicle taillight signals. In contrast to most existing work that relies purely on standard frame-based cameras for the taillight signal measurement, the presented mixed event/frame system extracts the frequency domain features from the spatial and temporal signal of each taillight region and measures the taillight signal by combining the active-pixel sensor (APS) frames and dynamic vision sensor (DVS) events. A thresholding algorithm and a learned classifier are proposed to jointly achieve the brake-light and turn-light signal measurement. Experiments with real traffic scenes demonstrate the performance of measuring taillight signals under different traffic conditions with a single event-based neuromorphic vision sensor. The results show the high potential of the event-based neuromorphic vision sensor being used for optical signal measurement applications, especially in dynamic environments.
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| 4. |
- Chen, Li-li, et al.
(författare)
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Multilayered polyelectrolyte-coated gold nanorods as multifunctional optical contrast agents for cancer cell imaging
- 2010
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Ingår i: Journal of Zhejiang University: Science B. - 1673-1581. ; 11:6, s. 417-422
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Tidskriftsartikel (refereegranskat)abstract
- We report the application of multilayered polyelectrolyte-coated gold nanorods (GNRs) as multifunctional optical contrast agents for cancer cell imaging. The surface modification of GNRs improves their chemical stability and facilitates them to be taken up by cancer cells through electrostatic interaction. The unique longitudinal surface plasmon resonance property of GNRs makes them suitable as both "scattering contrast agents" and "Raman contrast agents". In our experiments, the staining of GNRs in cells was further confirmed by dark field microscopy and Raman microscopy. Our experiment results indicated that GNRs have great potential as multifunctional "optical contrast agents" for future in vivo animal imaging.
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| 5. |
- Kang, Jian, et al.
(författare)
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Understanding in the morphology and tensile behavior of isotactic polypropylene cast films with different stereo-defect distribution
- 2014
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Ingår i: Journal of polymer research. - : Springer Science and Business Media LLC. - 1022-9760 .- 1572-8935. ; 21:6, s. 485-
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Tidskriftsartikel (refereegranskat)abstract
- In this study, two iPP resins with similar molecular weight and average isotacticity but different uniformities of stereo-defect distribution were used in the production of cast films. The crystalline morphology and orientation, and tensile behavior during room temperature stretching of the cast films were investigated by scanning electronic microscopy (SEM), 2D-wide angle X-ray diffraction (2D-WAXD) and 2D-small-angle X-ray scattering (2D-SAXS). It was found that under fixed processing condition, iPP with more uniform stereo-defect distribution (PP2) favors the formation of row nucleated lamellar structure during cast film production, and therefore exhibiting hard-elastic deformation behavior during stretching; meanwhile, the sample with less uniform stereo-defect distribution (PP1) shows un-oriented spherulitical morphology in the cast film, and typical plastic deformation behavior during stretching. The crystallization and rheological analysis on the iPP raw materials revealed that, the uniformity of stereo-defect distribution determines the ability of nucleation and crystallization, and further influences the response of the crystalline morphology to the elongation effect of cast film production process, which is of great importance in the structure-property design in the production of iPP membranes.
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