Solid State Phenomena Vols. 121-123

Abstract: The conformational modification of model peptide (lysozyme), which was solubilized in various concentrations of aqueous-ethanolic solutions (0-99% v/v), were characterized by circular dichroism and fluorometry. It was found that at 80% v/v ethanol, lysozyme changed its conformation to molten globule (MG) state. After HCl was introduced to achieve a solution of pH~2, only 35% v/v ethanol was required in order to initiate MG state. However, MG state was not generated when acidic solution was used alone without ethanol. This conformational change from native state to MG state was found to be reversible by simple aqueous dilution.

Abstract: Crucumin (diferuloylmethane) is a major active component of turmeric, but its bioavailability of oral administration is very low. In order to improve its pharmaceutical efficiency in oral use, poly (d,l-lactide) (PDLLA) nanospheres containing curcumin are successfully fabricated using a modified spontaneous emulsification solvent diffusion (SESD) method. The morphology, size and distribution of the resulting nanospheres are characterized by TEM and laser light scattering method. Drug contents in the nanospheres are calculated through UV spectrophotometer method. As a result, regular spherical PDLLA nanospheres containing curcumin are obtained and their effective diameters are 289 nm with narrow distribution (Pd=0.118)

Abstract: In the emerging field of nanobiotechnology, further downsizing the fluidic channels and pores to the nanometer scale are attractive for both fundamental studies and technical applications. The insulation Silicon nitride membrane nanofluidic channel arrays which have width ~50nm and depth ~80nm and length ≥20μm were created by focused-ion-beam instrument. The λ-DNA molecules were put inside nanochannels and transferred, a fluorescence microscopy was used to observe the images. Only by capillary force, λ-DNA molecules moved inside the nanochannels which dealt with activating reagent Brij aqueous solution. These scope nanostructure devices will help us study DNA transporting through a nanopore and understand more DNA dynamics characteristics.

Abstract: Fibrinogen and albumin are two of the most important plasma proteins that relate to blood coagulation caused by engineered surfaces. In this paper, the adsorption behavior of albumin and fibrinogen on single-walled carbon nanotubes nonwoven (SWNT nonwoven) was investigated through scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), near edge X-ray adsorption fine structure spectroscopy (NEXAFS) and direct enzyme-linked immunosorbent assay (ELISA) respectively. It was concluded that SWNT nonwoven displayed strong adsorption preference of fibrinogen to albumin. In addition, the immune activity of fibrinogen adhered to the SWNT nonwoven surface was found remained and showed a linear response to the concentration in a certain range.

Abstract: It is well known that metal dichalcogenides MS2 (M=Mo, W, Nb, Ta, TiS, Zr ,Hf, S=S, Se) have lamellar structure, the bonds of adjacent lamellae are weak van der Waals interactions and inter-lamellar are strong covalent interactions. The structures make adjacent lamellae easy to slip and it shows low friction coefficient during friction process. MS2 are often used as solid lubricants in high/low temperature, heave load and vacuum, in which oil is failure. WS2 has better high temperature properties than MoS2, although little natural WS2 mineral has been deposited, and people must synthesize it by chemical means, so its price is nearly 5 times expensive than that of MoS2. Until now little study is made comparing with MoS2. Furthermore the research papers about tribological behavior of NbS2, TaS2, TiS2, ZrS2, HfS2 are not seen. In this study the thermal decomposition method is used to produce fullerene-like MS2 nanotubes. The morphology, microstructure and tribological behavior of MS2 nanotubes are investigated by means of SEM, TEM, XRD and AFM. The results show that the diameter of MoS2, WS2 and NbS2 nanotube is less than 100nm, and the length is more than 2μm. The MoS2, WS2 nanotube has lower friction coefficient than MoS2 powder tested by AFM using Si3N4 probe. Similar results are also found for NbS2 nanotube. The macroscopic friction test for pin on disc tester shows nearly the same results. TEM image shows that MS2 nanotubes have rolling debris between two antagonist surfaces, and MoS2 powder only has flattened debris. It may be the fullerene structure brings the chemical stability and lead low friction.

Abstract: The effects of oxygen (O2) reactive ion etching (RIE) on the field emission (FE) properties of aligned CuO nanowire films are investigated systematically. It is found that the FE performance of the films is largely enhanced after initial exposure to reactive oxygen ions but degrades after extended treatment. As comparison, Ar RIE is also used to treat CuO nanowires, which, however, results in the deterioration of FE properties. The enhanced FE after O2 RIE is attributed to the shaper morphology, cleaner surface and better conductivity. On the other hand, increased work function and non-crystallized surface structure cause the deterioration of FE of CuO nanowires after Ar RIE treatments.

Abstract: Nanoscaled silicon cone arrays were formed on mirror-polished silicon wafers by plasma etching using hot filament chemical vapor deposition (HFCVD) system. A mixture of CH4 and H2 was introduced during silicon cone formation. AlN films were coated on Si cone arrays using radio frequency (RF) magnetron sputtering system. Scanning electrons microscopy (SEM) was employed to characterize the morphology of silicon cone arrays before and after AlN coating. The field emission characteristics of AlN coated silicon cone arrays，uncoated silicon cone arrays and AlN films were studied and compared, and the silicon cone arrays with AlN coating showed the best enhanced electron emission properties due to the negative electron affinity of AlN coating layer and the high aspect ratio of silicon cone. For AlN coated silicon cone arrays, a slight hysteresis between the upward and downward voltage sweeps was also observed and the field emission currents from AlN coated Si nanocone arrays decreased with the increase of the thickness of AlN films, which could be mainly attributed to the space charge buildup in AlN film with wide band gap.