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91.
The study aimed to distinguish genomic DNAs from nine species of plants belonging to six families and analyze their genetic relationship by using surface-enhanced Raman scattering (SERS). The silver nano-colloid and excitation wavelength of 785 nm used in this study yielded excellent quality of the SERS spectra. Raman signals were remarkably enhanced. Although the spectra for the nine species of plants appeared very similar, there were significant differences according to the analysis of variance analysis. There were three strong characteristic peaks. The peak at 625 cm−1 was due to the vibration overlap of C3′-endo/anti deoxyribose, cytosine, and guanine; the one at 715 cm−1 was due to the scissoring vibrations of C2N1C6 of adenine; and that at 1011 cm−1 was due to the stretching vibration of the CO bond of deoxyribose and vibrations of cytosine. The SERS data were smoothed and standardized and evaluated using second derivative analysis, principal component analysis, and hierarchical cluster analysis. A model was established using the data from hierarchical cluster analysis and principal components of the second derivative. The clustering result of this model was highly consistent with the traditional classification of plants; all plant species investigated were correctly clustered into classes according to the cluster distance coefficient among them; the accuracy of clustering was 100%. Chinese cabbage (Brassica pekinensis Rupr.) and green cabbage (Brassica chinensis L.) belonging to Cruciferae, maize (Zea mays L.) and bamboo (Sinocalamus affinis McClure) belonging to Gramineae, and magnolia (Magnolia delavayi Franch.) and champaca (Michelia alba DC.) belonging to Magnoliaceae were clustered into three separate classes, and fern (Nephrolepis auriculata L., Nephrolepidaceae), garlic (Allium sativum L., Amaryllidaceae), and ginkgo (Ginkgo biloba L., Ginkgoaceae) were each clustered into separate classes. These findings suggest that the SERS spectra of plant genomic DNAs can be used to classify species and analyze their genetic relationship. It is an effective and perfect supplement to traditional classification and can form the basis for genetic analysis. 相似文献
92.
Oleksandr Romanenko Petr Slepička Petr Malinsky Mariapompea Cutroneo Vladimír Havránek James Stammers Václav Švorčík Anna Macková 《Surface and interface analysis : SIA》2020,52(12):1040-1044
3D microstructures in pure poly(dimethylsiloxane) (PDMS) and PDMS with embedded Au nanoparticles were prepared by ion beam lithography without any further etching. Two mega-electron volts helium and 10 MeV oxygen ions were used for ion microstructuring. Parallel lines of 1 mm in length and 10 μm in thickness were fabricated for investigation of the effect of the nanoparticles presence in the polymer on the surface morphology of the created microstructures. The created microstructures were checked by optical microscope. Infrared (IR) spectrometry was used to study the effect of the ions type and fluence on the chemical changes of the material. Atomic force microscopy was used for the fine detail study as well as for checking the microstructure quality. Analysis revealed an increased radiation resistance of the nanocomposite compared to the pure PDMS. Shrinkage is proportional to the fluence, but the maximum value for both materials is limited by saturation. 3D microstructure in modified PDMS obtained at the same irradiation condition as pure PDMS is characterized by its smaller height. Obtaining the microstructure in nanocomposite of the same height as in pure PDMS by increasing the fluence can be impossible due to saturation of shrinkage and/or radiation-induced heating of the material. 相似文献
93.
《中国化学快报》2020,31(9):2202-2206
The triblock copolymer (PAA-b-PAN-b-PAA) is prepared by reversible addition-fragmentation chain-transfer polymerization, and then blended with polymer (PAN) and metal hydroxide (Ni(OH)2) as a precursor for heat-treatment. A composite material of hierarchical porous nanofibers and nickel oxide nanoparticles (HPCF@NiO) is prepared by electrospinning combined with high-temperature carbonization. The effects of the ratio of PAA and PAA-b-PAN-b-PAA on the internal structure of nanofibers and their electrochemical properties as positive electrode materials are investigated. The experimental results show that when the ratio of PAA to PAA-b-PAN-b-PAA is 1.3 to 0.4, it has good pore structure and excellent electrochemical performance. At the current density of 1 A/g, the specific capacitance is 188.7 F/g and the potential window is −1 V to 0.37 V. The asymmetric supercapacitor assembled with activated carbon as the negative electrode materials has a specific capacitance of 21.2 F/g in 2 mol/L KOH and a capacitance retention of 85.7% after 12,500 cycles at different current density. 相似文献
94.
Hang Kuen Lau Shruti Rattan Hongbo Fu Cristobal G. Garcia Dylan M. Barber Kristi L. Kiick Alfred J. Crosby 《Macromolecular bioscience》2020,20(5)
Local, micromechanical environment is known to influence cellular function in heterogeneous hydrogels, and knowledge gained in micromechanics will facilitate the improved design of biomaterials for tissue regeneration. In this study, a system comprising microstructured resilin‐like polypeptide (RLP)–poly(ethylene glycol) (PEG) hydrogels is utilized. The micromechanical properties of RLP‐PEG hydrogels are evaluated with oscillatory shear rheometry, compression dynamic mechanic analysis, small‐strain microindentation, and large‐strain indentation and puncture over a range of different deformation length scales. The measured elastic moduli are consistent with volume averaging models, indicating that volume fraction, not domain size, plays a dominant role in determining the low strain mechanical response. Large‐strain indentation under a confocal microscope enables the visualization of the microstructured hydrogel micromechanical deformation, emphasizing the translation, rotation, and deformation of RLP‐rich domains. The fracture initiation energy results demonstrate that failure of the composite hydrogels is controlled by the RLP‐rich phase, and their independence with domain size suggested that failure initiation is controlled by multiple domains within the strained volume. This approach and findings provide new quantitative insight into the micromechanical response of soft hydrogel composites and highlight the opportunities in employing these methods to understand the physical origins of mechanical properties of soft synthetic and biological materials. 相似文献
95.
Starch nanoparticle (SNP)‐based pressure sensitive adhesives (PSAs) with core‐shell particle morphology (starch nanoparticle core/acrylic polymer shell) are produced via seeded, semi‐batch emulsion polymerization at 15 wt% SNP loading (relative to total polymer weight) and 40 wt% latex solids. Crosslinker and chain transfer agent (CTA) are introduced to the acrylic shell polymer formulation at a range of concentrations according to a 32 factorial design to tailor the latex and adhesive properties of SNP‐based latexes. The crosslinker and CTA show no significant effect on polymerization kinetics, particle size, and viscosity. Latex gel content is predicted using an empirical model, which is a function of crosslinker and CTA concentration. Both the gel content and glass transition temperature strongly affect the adhesive properties (tack, peel strength, and shear strength) of the SNP‐based latex films. 3D response surfaces for the adhesive properties are constructed to facilitate the design of SNP‐based PSAs with desired properties. 相似文献
96.
Yu Xing Peng Jia Lin Liu Lin Feng Cun 《Journal of polymer science. Part A, Polymer chemistry》1996,34(17):3527-3530
endo-Dicyclopentadiene (DCPD) was polymerized by various cationic initiating systems in different solvents. IR and 1H NMR results show that four types of structural units are formed due to the corresponding addition modes: the addition on the norbornenic (NB) double bond generates unit I and rearranged unit II, while the addition on the cyclopentenic (CP) double bond produces unit III and rearranged unit IV. The reaction medium has a stronger effect on the microstructure of the polymer (PDCPD) than initiating systems. The polymers prepared in toluene and n-hexane contain all four structural units, while the polymer produced in methylene chloride is composed of structural units II and IV. © 1996 John Wiley & Sons, Inc. 相似文献
97.
98.
ABSTRACT The microstructure evolution and property change of four kinds of low silicon cast aluminum alloy exposed to heat for 0–50?h at 200°C were studied by means of Brinell hardness test, tensile property test, friction and wear property test and XRD analysis. The results show that with increasing thermal exposure time, the tensile strength of each group of samples decreased and the amount of wear increased. The tensile strength of samples with more Si content decreased slowly. When the time increased to 50?h, the increase of wear loss was the largest. The hardness of samples after thermal exposure increases compared with that before thermal exposure. The residual stress of (311) diffraction crystal surface of AlSi3.5Mg0.66 under different thermal exposure time was measured. The type of residual stress changed from residual tensile stress to residual compressive stress after thermal exposure. There is an abnormal phenomenon that the hardness of the sample increased and the amount of wear increased, and it is evident that the distribution of residual stress was inhomogeneous after thermal exposure. It is found that with increasing thermal exposure time to 50?h, the average lattice distortion ε of the low-index crystal plane and the high-index crystal plane in the aluminum alloys gradually increased. 相似文献
99.
100.
1 INTRODUCTION Bauxite porcelain is a novel “K2O–Al2O3–SiO2” system ceramic by using sintered bauxite, clay and potash feldspar and albite as the main raw materials with the Al2O3’s content of 50%~60(massfraction). Compared to the traditional“K2O–Al2O3–SiO2” feldspar porcelain by using quartz, bolus alb and potash feldspar and albite as the main raw materials, the bauxite porcelain possesses such advantages as high mechanical strength, excellent electrical insula- tion prop… 相似文献