Some Factors Affecting the Interfacial Interaction at Thermomechanical Pulp Fiber and Polypropylene Interphase

This dissertation focused on some selected factors that influence the interfacial interactions at the interphase between wood based materials and thermoplastic surfaces. Several treatments were applied to enhance interfacial properties. In general, interfacial properties were altered by physical and chemical surface modification. Study of the interfacial interactions between wood fiber surfaces as a reinforced material and thermoplastics as a matrix material is important to understand fundamentals of wood fiber-plastic composites (WPC). This study represents fundamental research to define treatment effects on surfaces of wood pulp fibers and polypropylene (PP) film. Two thermosets, ion implantations, and maleic anhydride (MA) grafting were used to increase interfacial adhesion between wood based materials and PP. Thermoset resins were applied at three levels to fiber handsheets and PP film laminates. The surface treatment increased shear and tensile strength properties and PP crystallinity ( ) as determined by differential scanning calorimetry (DSC). The ion implantation method using oxygen and argon as ion sources proved to be one of the most effective treatments to improve interfacial bonding between thermomechanical pulp (TMP) fibers and PP film. Oxygen plasma treatment was more effective than argon to increase tensile strength due to the electron donor and accepter mechanism generated by magnetic fields between two electrodes. The MA grafting effect also improved the tensile strength of TMP fiber handsheets and PP film laminates fabricated with a 50/50 weight fraction. A brittle failure was observed by scanning electron microscopy (SEM) at the fracture surface of tensile specimens made from TMP fiber handsheets and PP film laminates (TPL). It was found by using extraction with CH2Cl2 and H2O as solvents that the PP nucleation ability on fiber surfaces was extremely reduced due to the removal of deposit materials from the surface. Thus, the extractives on the wood/non-wood fiber surface played a potential role for surface induced nuclei and lamella deposits for the PP melts. In conclusion, the surface treatments of ion implantations, thermoset treatment, and MA modification enhanced interfacial strength of TPL. Electron interaction and mechanical interlocking in the wood fiber handsheet improved interfacial interactions between wood-based materials and PP

High-speed and high-SNR photoacoustic microscopy based on a galvanometer mirror in non-conducting liquid

Optical-resolution photoacoustic microscopy (OR-PAM), a promising microscopic imaging technique with high ultrasound resolution and superior optical sensitivity, can provide anatomical, functional, and molecular information at scales ranging from the microvasculature to single red blood cells. In particular, real-time OR-PAM imaging with a high signal-to-noise ratio (SNR) is a prerequisite for widespread use in preclinical and clinical applications. Although several technical approaches have been pursued to simultaneously improve the imaging speed and SNR of OR-PAM, they are bulky, complex, not sensitive, and/or not actually real-time. In this paper, we demonstrate a simple and novel OR-PAM technique which is based on a typical galvanometer immersed in non-conducting liquid. Using an opto-ultrasound combiner, this OR-PAM system achieves a high SNR and fast imaging speed. It takes only 2 seconds to acquire a volumetric image with a wide field of view (FOV) of 4 x 8 mm(2) along the X and Y axes, respectively. The measured lateral and axial resolutions are 6.0 and 37.7 mu m, respectively. Finally, as a demonstration of the system's capability, we successfully imaged the microvasculature in a mouse ear in vivo. Our new method will contribute substantially to the popularization and commercialization of OR-PAM in various preclinical and clinical applications.11Ysciescopu

Maleated Polypropylene Film and Wood Fiber

The grafting effect of maleic anhydride (MA) as an interfacial bonding agent and its influence on the tensile strength properties of thermomechanical pulp handsheet-isotactic polypropylene (iPP) film laminates was studied. For the MA treated with benzoyl peroxide (BPO) as an initiator, tensile strength properties increased 76 % with PP film over untreated laminates. The optimal strength properties were obtained with a MA and BPO ratio of 2:1. A strong correlation was observed between the number of fibers in the web and tensile strength properties for both handsheet drying conditions. The R 2 values were 0.95 for air-dry conditions and 0.94 from oven-dry conditions. Scanning electron microscopy images also showed the effectiveness of MA loading on the surface of thermomechanical pulp fibers due to increased fiber failure, which occurred without fiber being pulled out from the PP matrixes. Crystallinity and heat flow were determined using differential scanning calorimetry (DSC) and increased as expected as the ratio of MA and BPO increased from 0:0 to 2:1. These results were also in accordance with the morphological observations at the fracture surface, Fourier transform infrared spectra, and thermal analysis. POLYM. COMPOS., 00:000–000, 2008. ª 2008 Society of Plastics Engineer

ABSTRACT VIEWER RESPONSES TO INTEACTIVE NARRATIVE: A COMPARISION OF INTERACTIVE VERSUS LINEAR VIEWERSHIP IN ALINE AND GROUP SETTING By

Based on researches about viewers ’ emotional responses to media, the emotional responses to interactive video were studied. Because of the nature of interactive television, the involvement of people during watching the video was expected to be increased. This paper presents results from various emotional factors, which were used to measure viewers ’ responses to other media forms. Also emotional factors of subjects wh

Understanding high anisotropic magnetism by ultrathin shell layer formation for magnetically hard–soft core–shell nanostructures

Magnetic core–shell nanostructures offer a viable solution for tunable magnetism via nanoscale exchange interactions in a single-component unit. A typical synthetic approach for monodisperse bimagnetic ferrite core–shell nanostructures employs the seed-mediated growth method using the heating-up process. Understanding magnetic core–shell interface formation and their interactions is crucial; however, the magnetical persistence of the pristine core component during the heating-up process is unclear. Here, we elucidate the enhancement mechanism of magnetic anisotropy when the hard–soft core–shell nanostructures are formed with the ultrathin shell layer. The heating-up effect on the core component exhibits the coordination change of ligand chemisorption with surface metal ions, which leads to a substantial increase in surface anisotropy due to enhanced spin–orbit couplings. We further demonstrate that the selection of metal precursors and surfactants for additional shell layer formation is important. The kinetic of the shell formation rate by their thermolysis and atomic-scale surface etching by the surfactant led to the disordering of surface spins on the core parts. Our observations provide the underlying mechanism of high anisotropic magnetism while bimagnetic ferrite core–shell interface formation and the voyage of synthetic procedures for the additional shell layer are critical to an outcoming magnetism.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF2018R1D1A1B07044481)

Morphological work function dependence of rare-earth disilicide metal nanostructures

The work functions of various DySi(2-x) nanostructures epitaxially grown on a Si(001) surface were correlated with the structure using high-resolution Kelvin probe force microscopy and scanning tunneling microscopy in ultrahigh vacuum. Dy adatoms induce a surface dipole on Si(001) that increases the surface potential from 0.26 to 0.42 eV with respect to 2 x 1 reconstructed Si(001). DySi(2-x) nanowires showed a 0.2-0.23 eV lower work function than DySi(2-x) nanoislands, which can be attributed to confinement of electrons along the surface normal that induces a surface dipole when the film thickness approaches the Fermi wavelength. The ability to tune the work function of metal nanostructures should be useful for understanding how electronic structure affects catalytic activity

Alkaline Metal Reagent-Assisted Synthesis of Monodisperse Iron Oxide Nanostructures

The solvothermal decomposition of iron complexes using the heat-up process enables monodisperse Fe3O4 nanoparticle synthesis. Here, we demonstrate that the high reduction potential capability of alkaline metal reagents in the reductive environment allows for pure magnetite phase formation at 200 °C, which is lower than that of typical synthetic method and offers highly crystalline superparamagnetic and ferrimagnetic nanostructures with the ability to control uniformity including spherical and cubic morphology with narrow size distributions. Our method involved reduction of the acetylacetonate and acetate anions to aldehyde and alcohol as an oxygen resource for iron oxide nucleation in an inert condition. For confirming the developed pure surface phase of alkaline metal reagent-assisted magnetite nanoparticle, the magnetic field-dependent shifting of blocking temperature was investigated. The degree of the exchange interaction between core spins and disordered surface spins is attributed to the ratio of core spins and disordered surface spins. The decrease in disordered surface spins deviation due to an enhanced pure phase of magnetite nanoparticles exhibited the negligible shift of the blocking temperature under differently applied external field, and it demonstrated that alkaline metal reagent-induced reductive conditions enable less formation of both disordered surface spins and biphasic nanostructures