Tzu-Hsuan Kao

Interleukin-1 receptor antagonist attenuates the heat stroke-induced neuronal damage by reducing the cerebral ischemia in rats

The effects of interleukin-1 receptor antagonist (IL-Ira) on both local cerebral blood flow and neuronal damage of the hypothalamus, corpus striatum, cortex or thalamus were assessed in rats with heat stroke. Heat stroke was induced by exposing the urethane-anesthetized rats to a high ambient temperature (42 degrees C). Damage to the hypothalamus, corpus striatum, cortex or thalamus was scored on a scale of zero to three modified from the grading system of Pulsinelli and colleagues in which: 0 = normal, 1 = few neurons damaged, 2 = many neurons damaged, and 3 = all neurons damaged. During the onset of heat stroke, as compared to those of normothermia controls, the heat stroke rats displayed a higher value of colonic temperature or neuronal damage score, as well as a lower value of local cerebral blood flow or mean arterial blood pressure. In addition, compared to those of normothermic, control rats, the heat stroke rats had increased interleukin-1 and tumor necroting factor production in the diencephalon, brain stem and cortex. The heat stroke-induced neuronal damage and diminished local cerebral blood flow in different brain structures, as well as the systemic hypotension, were attenuated in animals pretreated with IL-1ra (200 micrograms/kg, iv) 30 min before the onset of heat stroke. The results indicate that IL-1ra attenuates the heat stroke-induced cerebral neuronal damage by reducing cerebral ischemia in rats.

One-step synthesis of uniform silver nanoparticles capped by saturated decanoate: direct spray printing ink to form metallic silver films

The one-step synthesis and spectroscopic characterizations of size-controlled silver nanoparticles are described. The transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric-mass analysis (TGA-MS) and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize the decanoate-protected silver nanoparticles. TEM analysis showed that spherical nanoclusters of 7.52 +/- 0.57 nm were produced. Furthermore, the particle sizes are uniform with a narrow size distribution. For all samples, Ag 3d(5/2) and 3d(3/2) components appeared at 368.5 and 374.5 eV, respectively, in the XPS spectrum; these values compare very well with the typical values of carboxylate-protected Ag nanoparticles. A thermal analysis mass spectrometer was used to analyze the desorption behavior of decanoate-protected nanoparticles. From the desorption maximum temperatures of 181 and 263 degrees C, activation energies of 27.2 and 32.2 kcal mol(-1) for the desorption processes in the Ag MPCs were obtained, assuming a first-order reaction and using a pre-exponential factor of 1 x 10(13) s(-1). A specific resistivity of 6.097 microOmega cm for the silver metal film (0.7 microm) on a Si wafer can be produced simply by thermal annealing of an Ag monolayer-protected clusters film under an atmosphere of 90% N(2)-10% H(2) at 300 degrees C for 1 h.

Continuity and adhesion of Au deposits on electronic substrates by utilizing nanoparticle suspensions

Since nanosized metals exhibit a considerably lower melting point compared to bulk materials, nanometallic particle coated films can be deposited and cured to obtain electric conductors at a relatively low processing temperature. In this study, suspensions with Au nanoparticles of average size 3.9 ± 0. 7n m were prepared and spin-coated onto several commonly used electronic substrates (Cu, Ni and Al), and then thermally processed in a protective atmosphere. Experimental results show that the degree of continuity of the coated film on the Cu substrate was better than that on the Ni substrate, which was in turn better than the Al substrate. It was also found that isothermally heating the suspension at 300 ◦ C, a temperature greater than the melting point of the nanoparticles used, could produce fine Au deposits with acceptable adhesion. Worthy of notice is that, after a proper curing treatment, Au layers deposited with nanoparticle suspension exhibited superior adhesion to those produced by sputtering. (Some figures in this article are in colour only in the electronic version)

Observations on the melting of Au nanoparticle deposits and alloying with Ni via in situ synchrotron radiation x-ray diffraction

Through monitoring the evolution of the x-ray diffraction peaks, the transient low temperature melting of Au nanoparticles and following alloying with the substrate were demonstrated via in situ synchrotron radiation x-ray diffraction. Upon heating, the broad diffraction peak of nanosized Au particles with the average diameter of 2.5 nm was suppressed at about 200 °C and soon became sharp due to melting and subsequent solidification. If the test was conducted on a Ni film, an unstable intermetallic compound Au3Ni appeared with crystallized Au, which resulted from the reaction between the supercooled liquid of Au and Ni. However, it decomposed at 275 °C and above.

Interdiffusion behavior at the interfaces between deposits of Au nanoparticles and electronic substrates

This study investigated the interfacial behavior between thiol-stabilized Au nanoparticle (NP) deposits and the commonly used electronic substrates, Cu, Ni and Ag. Instead of sintering or agglomerating, curing at 300 ◦ C resulted in either entire or partial melting of the deposited suspension because of the substantially low melting point of the Au NPs due to the nanosize effect; the melting point was measured to be 230‐270 ◦ C. Thus a liquid‐solid reaction might occur between the NP Au deposits and substrates during the thermal process. The elemental depth profiles examined by x-ray photoelectron spectroscopy (XPS) demonstrated that stoichiometric intermetallic phases, likely Cu3Au and NiAu3, existed respectively at the Au/Cu and Au/Ni interfaces, while a miscible solid solution of nonstoichiometric layer was found to have emerged at the Au/Ag interface. Also, the chemical shifts of binding energies inspected at the reaction layers reflected the alloying behavior at those interfaces. (Some figures in this article are in colour only in the electronic version)

Observations on PVP-protected noble metallic nanoparticle deposits upon heating via in situ synchrotron radiation X-ray diffraction.

Through monitoring the evolution of the X-ray diffraction peaks, the phase transformation of PVP-protected Ag and Au nanoparticle deposits (NPDs) on electronic substrates of Cu and Ni upon heating in air was investigated via in situ synchrotron radiation X-ray diffraction. With an increasing temperature, the broad diffraction peak of nano-sized Ag and Au particles with the original average diameters of 4.2 nm and 9.6 nm, respectively, became sharp because of particle coarsening and coalescence. Complex phase transitions among Au, Cu, AuCu(3) and CuO(x) were observed, mainly due to the negative enthalpy of mixing between Au and Cu. The interactions between NPDs and the substrates affected the shift of diffraction peaks to lower angles, caused by thermal expansion and also the temperature for the oxide formation. Compared to Au, Ag NPDs did not form intermetallic compounds with Cu and the formation of copper oxides can also be retarded mainly due to the phase separation feature of the Ag-Cu system.

Constructions of silver nanowires and copper oxide microrings by a surface-formation technique

We demonstrate a simple method to synthesize silver wires by thermal reduction of aqueous AgNO(3) droplet with catalytic anatase TiO(2) nanoparticles which were spin-coated on Si wafer. Structural characterization of the silver wires shows that the nanowires grow primarily along the [011] direction. SEM image of the silver wires clearly shows the catalytic TiO(2) nano-cluster attached to the end of the each silver wire. Since the process was surfactant-free, the silver nanowires prepared by our method retain the excellent electrical conductivity. The intrinsic resistivity calculated from the current-voltage curve for a wire with 12880.41 nm(2) cross-section area was 18.72 microohm cm, which is about 11.6 times higher than that of bulk silver (1.61 microohm cm). Our simple method can be also applied to generate CuO with ring-shaped microstructure by using ITO conducting glass as matrix. We have found that the size and reproducibility are well-controllable. A single phase of CuO ring-shaped microstructure with outer diameters ranging from approximately 13 to 17 microm and inner diameters ranging from approximately 1.4 to 3.3 microm was obtained. The composition of CuO microring was confirmed by thin-film XRD and XPS analyses.

Phase transformation of metallic nanoparticle deposits for the electrodes of flexible electronics

Suspensions with metallic nanoparticles have been widely used to fabricate conductive lines and electrodes for flexible electronic devices under a relatively low processing temperature. This study prepared thiol-stabilized Au nanoparticle suspension and investigated phase transformation of the Au nanoparticle deposits (NPDs) upon heating via in-situ synchrotron radiation X-ray diffraction. With an increasing temperature, the broad diffraction peak of nanosized Au particles with the average diameter of 3nm can be suppressed at around 200°C and soon becomes sharp due to melting and the following solidification. When deposited on the commonly-used electronic substrate, Cu, liquid-solid reaction might occur between the NPDs and the substrate during the thermal process. The low temperature alloying behavior and the formation of the Cu3Au superlattices were manifested by SIMS, XPS and GIXRD.