An in situ transmission electron microscope investigation into grain growth and ordering of sputter-deposited nanocrystalline Ni3Al thin films

The grain growth kinetics and ordering behavior of direct-current magnetron sputter-deposited Ni75at.%Al25at.% alloy films were investigated using in situ isothermal annealing in a transmission electron microscope. Both normal and abnormal grain growth modes were observed. The normal grain growth kinetics under isothermal heating from 300 to 700°C were found to comply with the Burke law d = K/dn-1, where d is grain size and K and n are constants with respect to time. The grain boundary mobility parameter K was found to obey an Arrehnius rate law with an apparent activation energy of 1.6 eV, and n was found to increase gradually from 5.2 at 300°C to 8.7 at 700°C. Abnormal grain growth occurred at 500°C or higher, and grain coalescence was identified as an important operative mechanism. It was also observed that the initially as-deposited state of the films was crystalline with a disordered face-centered-cubic structure, but ordering into the equilibrium Ll2 intermetallic structure followed from annealing at temperatures above approximately 500°C.published_or_final_versio

Insulator-metal transition in nanostructured Ni-Al thin films

The electrical resistance of Ni-Al alloy thin films prepared by dc magnetron sputtering process was found to be abnormally high at room temperature. However, when heated at elevated temperatures, the resistance dropped significantly, exhibiting a remarkable negative temperature coefficient of resistance (TCR). The phenomenon was found to be substrate-independent. Cross-sectional transmission electron microscopy revealed that the films were essentially nanocrystalline and porous in nature. Analysis of the current density-electric field characteristics yielded a satisfactory agreement with either the space charge limited or the Poole-Frenkel models for electrical conduction. The negative TCR effect diminishes and the usual metallic resistance is restored in thicker films, probably due to reduction in particle separation and further coalescence of neighbouring crystallites.published_or_final_versio

Metal-to-insulator transition in sputter deposited 3Ni/Al thin films

Thin films with a 3Ni/1Al atomic ratio were synthesized using low-power dc planar magnetron sputtering from a nickel–aluminum alloy target. Chemical analysis revealed that a significant amount of oxygen was incorporated into the Ni–Al thin films which were prepared under a typical vacuum of ~1×10–5 mbar. These thin films were found to exhibit a prominent temperature dependence of electrical resistance, the magnitude of which diminishes upon increasing the film thickness or the in situ deposition temperature. Cross-sectional transmission electron microscopy revealed a nanocrystalline structure of the films which changes as a function of deposition temperature. Electron diffraction indicates the existence of a single-phase face-centered cubic structure in the nanocrystallites, yet with an enormous expansion of the crystal lattice for the low temperature deposited films when compared with the intermetallic Ni3Al lattice. On raising the deposition temperature or increasing the film thickness, however, the lattice constant gradually declines toward the lattice constant of bulk Ni3Al. An attempt is made to correlate the lattice structures of the crystallites and the electrical properties of the films with the potential influence of the dissolved oxygen in the Ni–Al lattice. © 2000 American Institute of Physics.published_or_final_versio

Development of murine model of autoimmune thyroiditis induced with homologous mouse thyroid perioxidase

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Strain-rate sensitivity of hardness of nanocrystalline Ni75at.%Al25at.% alloy film

Room-temperature indentation experiments carried out on nanocrystalline Ni75at.%Al25at.% alloy films with a range of grain sizes revealed that the strain-rate sensitivity of hardness is nearly zero and that the hardness increases as grain size decreases. The strain-rate insensitivity of hardness indicates that the room-temperature strength of these alloy films is dominated by an athermal, strain-rate-insensitive component. The hardness of the films was found to be in the range of 2.4 to 3.3 GPa, depending on grain size.published_or_final_versio

An assessment of the mechanical strengths of aluminide-based thin coatings

Titanium aluminide and nickel aluminide-based thin coatings were synthesized by magnetron sputtering from intermetallic TiAl and Ni3Al alloy targets on nickel substrates. Both types of aluminide coating exhibited high surface hardness values that varied with the degree of heat treatment. The hardness of the coatings was investigated using micro- and nano- indentation techniques. In order to estimate the intrinsic strength of the films, the indentation size effects of the apparent hardness were analyzed by the Jönsson-Hogmark model and a model recently proposed by the authors. The analysis indicated that the strengths of the aluminide coatings may considerably exceed their strengths in bulk.published_or_final_versio

Determination of Chlorinated organic compounds in aqueous matrices

Thirteen pure volatile, semi-volatile and non-volatile chlorinated organic compounds of molecular weights ranging from trichloroethylene (MW = 131.39 g mole -¹) to hexachlorobenzene (MW = 284.78 g mole-¹) were determined in aqueous matrices by GC-ECD. After 10% salt addition, different extraction tests were performed using fibres whose adsorbing phase was based on microsphere carbon particles characterized by a constant size. Five experimental parameters were optimized: extraction temperature and time, position of the fibre in the GC injector port, desorption temperature and time. The optimized analytical protocol was employed to determine the efficiency of a real activated carbon adsorption plant to remove organic chlorinated pollutants from an industrial wastewater at ng l-¹ levels

Herba Epimedii: Anti-oxidative properties and its medical implications

Herba Epimedii is a Chinese herbal medicine with proven efficacy in treating cardiovascular diseases and osteoporosis, and in improving sexual and neurological functions. This efficacy is found to be related to the potent anti-oxidative ability of Herba Epimedii and its flavonoid components, with icarrin as the main effective constituent, along with polysaccharides and vitamin C. These ingredients have been proven to be effective against oxidative-stress related pathologies (cardiovascular diseases, Alzheimer's disease and inflammation) in animal rodent models and in vitro studies. Their antioxidative properties are found to be related to an inductive effect on endogenous freeradical scavenging enzymes such as catalase and glutathione peroxidase and the inherent electron-donating ability of flavonoids. © 2010 licensee MDPI, Basel, Switzerland.published_or_final_versio

Markerless Video Analysis for Movement Quantification in Pediatric Epilepsy Monitoring

This paper proposes a markerless video analytic system for quantifying body part movements in pediatric epilepsy monitoring. The system utilizes colored pajamas worn by a patient in bed to extract body part movement trajectories, from which various features can be obtained for seizure detection and analysis. Hence, it is non-intrusive and it requires no sensor/marker to be attached to the patient’s body. It takes raw video sequences as input and a simple user-initialization indicates the body parts to be examined. In background/foreground modeling, Gaussian mixture models are employed in conjunction with HSV-based modeling. Body part detection follows a coarse-to-fine paradigm with graphcut-based segmentation. Finally, body part parameters are estimated with domain knowledge guidance. Experimental studies are reported on sequences captured in an Epilepsy Monitoring Unit at a local hospital. The results demonstrate the feasibility of the proposed system in pediatric epilepsy monitoring and seizure detection

Anti-metastatic mechanism of Tian-Xian Liquid (TXL) and its bioactive fractions in human colorectal cancer cells and xenograft models

Poster Session A: abstract no. 29Colorectal carcinoma is the second most prevalent cancer with an up-rising trend in Hong Kong (Hong Kong Cancer Registry). Traditional Chinese medicine acts as a complementary alternative for tumour therapy with minimal side-effects and traumatic injuries. Tian-Xian Liquid (TXL), one of the well-known natural medicinal herbal formulations, has been commercially used as an anticancer dietary supplement for a decade without known adverse effects. This study aimed to investigate the anti-metastatic property of TXL and its bioactive fractions [butanol fraction (BU), ethyl-acetate fraction (EA) and aqueous fraction (WA)] at molecular level on human colorectal cancer in vitro (HT-29 cancer cells) and in vivo (nude mice xenografts). For the cell model, TXL and its bioactive fractions have similar anti-proliferative effects by MTT assay. At 4-hour-incubation, IC50 values were obtained at 1% (V/V) TXL, 1.25% (V/V) BU, 5% (V/V) EA and 0.3125% (V/V) WA. At IC50, TXL and its bioactive fractions significantly reduced the MMP2 and MMP7 expressions at mRNA level by real-time PCR. At protein level, TXL, BU and EA correspondingly down-regulated MMP2 (active form) and MMP7 protein from 24 to 48 hours; TXL and BU also down-regulated VEGF protein expression; however, no such effect was found in WA-treated cells. Further, only TXL, EA and WA effectively inhibited the cell migration at 48 hours incubation by woundhealing assay. For the xenografts models, MMP2 and MMP7 mRNA expressions were reduced by TXL-, BU- and EA-treated xenografts; however no effects on MMP2 protein expression in all drug-treated xenografts. The VEGF protein expression was significantly down-regulated in TXL- and WA-treated xenografts. Further, TXL, BU and WA effectively inhibited the tumor growth without altering the body weight of the xenografts. In summary, the Chinese medicinal formulation, TXL, demonstrated the most effective anti-metastatic ability on human colorectal cancer in vitro and in vivo.published_or_final_versio