The therapeutic value of specific fibres is partly dependent on their fermentation characteristics. Some fibres are rapidly degraded with the generation of gases that induce symptoms in patients with irritable bowel syndrome (IBS), while more slowly or non-fermentable fibres may be more suitable. More work is needed to profile a comprehensive range of fibres to determine suitability for IBS. Using a rapid in vitro fermentation model, gas production and metabolite profiles of a range of established and novel fibres were compared. Fibre substrates (n 15) were added to faecal slurries from three healthy donors for 4 h with gas production measured using real-time headspace sampling. Concentrations of SCFA and ammonia were analysed using GC and enzymatic assay, respectively. Gas production followed three patterns: rapid (≥60 ml/g over 4 h) for fructans, carrot fibre and maize-derived xylo-oligosaccharide (XOS); mild (30–60 ml/g) for partially hydrolysed guar gum, almond shell-derived XOS and one type of high-amylose resistant starch 2 (RS2) and minimal (no differences with blank controls) for methylcellulose, another high-amylose RS2, acetylated or butyrylated RS2, RS4, acacia gum and sugarcane bagasse. Gas production correlated positively with total SCFA (r 0·80, P < 0·001) and negatively with ammonia concentrations (r –0·68, P < 0·001). Proportions of specific SCFA varied: fermentation of carrot fibre, XOS and acetylated RS2 favoured acetate, while fructans favoured butyrate. Gas production and metabolite profiles differed between fibre types and within fibre classes over a physiologically relevant 4-h time course. Several fibres resisted rapid fermentation and may be candidates for clinical trials in IBS patients.

The remaining challenges, developing the relativistic electron beam sources, stimulate the investigations of cathode materials. Carbon-fiber-aluminum composite is the most appropriate cathode materials to construct the robust relativistic electron beam sources. Carbon-fiber-aluminum composite is treated by a non-equilibrium atmospheric plasma torch with a copper electrode based on high-voltage gas discharge. The axial and radial distributions of the plasma torch temperature are measured to determine the optimal treatment temperature and location. Copper-oxide particles with diameters of less than 1 µm are deposited onto the surface of the carbon-fibers and a layer of copper-oxide covers the entire surface as the treatment time is increased. Raman spectroscopy suggests that although the locations of the D and G band are similar, the areas of the D and G bands increase after the plasma treatment due to the reduced graphite crystalline size in the carbon-fibers. Analysis of the copper electrode surface discloses materials ablation arising from the discharge which releases copper from the source. Our results reveal that the atmospheric plasma torch generated by high-voltage discharge is promising in the surface modification of the carbon-fiber-reinforced aluminum composite. Further, the plasma produced by atmospheric plasma torch is dusty plasma, due to the participation of liberated copper particles. The plasma torch was analyzed by fluid dynamics, in terms of plasma density, plasma expansion velocity, and internal pressure, and it was found that the plasma produced by atmospheric torch is supersonic flow.

Adsorption of Escherichia coli (E. coli) cells on red mud (RM) is important in the interactions between RM and bacteria. The objective of this work is to study adsorption of E. coli onto RM and to determine its influence in relation to the surface properties of RM. The effects of different calcination temperatures on the surface properties of red mud were investigated by thermogravimetric analysis, x-ray diffraction, scanning electron microscopy, Brunauer, Emmett, Teller (surface measurement)/N2 adsorption method, and zeta potential analysis. A higher adsorption capacity was observed from RM calcinated at 700 °C (RM700) due to larger pores formed on the surface of RM. The correlation between the adsorption efficacy and surface properties of RM is discussed and the extended Derjaguin-Landau-Verwey-Overbeek theory suggests that when the adsorption reaches equilibrium, the increased adsorption of E. coli onto RM is due to the smaller energy barrier between E. coli and RM700 as compared with that between E. coli and raw RM (RM0).

Surface-enhanced Raman scattering (SERS) coupled with micro- or nanofluidics integrated into optofluidic devices offer many advantages over conventional SERS conducted under static conditions. Higher reproducibility, larger intensity, as well as greater enhancement can be achieved by efficient mixing of analytes and SERS enhancers under a continuous flow. Progress and advances in the past 10 years, including the design of channels and efficient mixing conditions, assemblies of SERS substrates for optimal enhancement, and advantages of optofluidic-SERS analysis, are reviewed. Recent results show that optofluidic-SERS effectively overcomes many of the difficulties and limitations plaguing conventional SERS and the novel technique has enormous application potential.

Electroplastic manufacturing processing (EPMP) is a relatively new metal-forming process that is energy efficient, environmentally friendly, and versatile. In particular, it can be used to manufacture metals or alloys that are difficult to process by conventional manufacturing protocols. There have been significant advances in EPMP in the past decade, and this review summarizes our current state of understanding and describes recent developments in EPMP. Particular emphasis is placed on describing the mechanisms responsible for the electroplastic effect and microstructure evolution as well as major advances in EPMP of metals. Challenges facing theoretical and experimental investigations are also discussed.

Despite many investigations on the corrosion behavior of NiTi shape memory alloys (SMAs) in various simulated physiological solutions by electrochemical measurements, few have reported detailed information on the corrosion products. In the present study, the structure and composition of the corrosion products on NiTi SMAs immersed in a 0.9% NaCl physiological solution are systematically investigated by scanning electron microscopy (SEM), x-ray energy dispersion spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS). It is found that attack by Cl− results in nickel being released into the solution and decrease in the local nickel concentration at the pitting sites. The remaining Ti reacts with dissolved oxygen from the solution to form titanium oxides. After long-term immersion, the corrosion product layer expands over the entire surface and XPS reveals that the layer is composed of TiO2, Ti2O3, and TiO with relatively depleted Ni. The growth rate of the corrosion product layer decreases with immersion time, and the corrosion product layer is believed to impede further corrosion and improve the biocompatibility of NiTi alloy in a physiological environment. It is found that the release rate of nickel is related to the surface structure of the corrosion product layer and immersion time. A corrosion mechanism is proposed to explain the observed results.

The microstructure and texture evolution in a cold-rolled AZ31 magnesium alloy during electropulsing treatment (EPT) are investigated and correlated with the mechanical properties. The microstructure is effectively refined, and a tilted basal texture develops gradually during EPT. The yield stress in the treated samples is lower than that in the cold-rolled sample, indicating that texture softening is dominant over strengthening because of grain refinement. The phenomenon is primarily the result of the tilted basal texture. EPT improves the tensile ductility of the EPT samples significantly, albeit slightly compromising the tensile strength. The mechanism of the microstructure evolution during electropulsing is discussed from the viewpoint of grain-boundary motion. Moreover, the ductility enhancement is discussed in terms of the deformation mechanism and texture of the Mg alloy.

Magnesium alloys are potential materials in biodegradable hard tissue implants. Their degradation products in the physiological environment not only affect the degradation process but also influence the biological response of bone tissues. In the work reported here, the composition and structure of the corrosion product layer on AZ91 magnesium alloy soaked in a simulated physiological environment, namely simulated body fluids (SBFs), are systematically investigated using secondary electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and in situ monitoring of the corrosion morphology. Our results show that the corrosion product layer comprises mainly amorphous magnesium (calcium) phosphates, magnesium (calcium) carbonates, magnesium oxide/hydroxide, and aluminum oxide/hydroxide. The magnesium phosphates preferentially precipitate at obvious corrosion sites and are present uniformly in the corrosion product layer, whereas calcium phosphates nucleate at passive sites first and tend to accumulate at isolated and localized sites. According to the cross sectional views, the corrosion product layer possesses a uniform structure with thick regions several tens of micrometers as well as thin areas of several micrometers in some areas. Localized corrosion is the main reason for the nonuniform structure as indicated by the pan and cross-sectional views. The results provide valuable information on the cytotoxicity of magnesium alloys and a better understanding on the degradation mechanism of magnesium alloys in a physiological environment.

Near-equiatomic porous nickel-titanium shape memory alloys (NiTi SMAs) are becoming one of the most promising biomaterials in bone implants because of their unique advantages over currently used biomaterials. For example, they have good mechanical properties and lower Young�s modulus relative to dense NiTi, Ti, and Ti-based alloys. Porous NiTi SMAs are relatively easy to machine compared to porous ceramics such as hydroxyapatite and calcium phosphate that tend to exhibit brittle failure. The porous structure with interconnecting open pores can also allow tissue in-growth and favors bone osseointegration. In addition, porous NiTi alloys remain exhibiting good shape memory effect (SME) and superelasticity (SE) similar to dense NiTi alloys. To optimize porous NiTi SMAs in bone implant applications, the current research focuses on the fabrication methods and surface modification techniques in order to obtain adjustable bone-like structures with good mechanical properties, excellent superelasticity, as well as bioactive passivation on the entire exposed surface areas to block nickel ion leaching and enhance the surface biological activity. This invited paper describes progress in the fabrication of the porous materials and our recent work on surface nanorization of porous NiTi scaffolds in bone grafts applications.

The mechanical properties of thin films are frequently evaluated using nanoindentation. The finite element method (FEM) is very effective for investigating the stress and strain fields of the film–substrate system during nanoindentation. However, the role of residual stress and the thin interlayer between the film and substrate is not well known, especially when the hard coating/interlayer/soft substrate are considered together. In this work, the FEM is used to investigate the load-displacement behavior of the hardness of the hard coating/interlayer/soft substrate system. The load–displacement process is simulated, and the effects of different residual stresses and interlayer thicknesses are discussed.

Magnesium alloys are potential biodegradable biomaterials in hard tissue implants. However, the fast degradation rate in the biological environment has hampered widespread applications. We propose to use a ZrO2 coating in conjunction with a Zr transition layer to improve the corrosion resistance of AZ91 magnesium alloy. X-ray photoelectron spectroscopy discloses that the coating is composed of ZrO2. The Vickers hardness measurement demonstrates that the surface hardness of the alloy is significantly enhanced. The electrochemical behavior of the coated sample is systematically evaluated by means of potentiodynamic polarization, open-circuit potential evolution, and electrochemical impedance spectroscopy. The electrochemical results indicate that the corrosion resistance of the coated alloy is enhanced significantly, and the electrode-controlled processes in a coated alloy–solution system are discussed.

The objective of this study is to investigate the corrosion susceptibility of surgical AZ91 magnesium alloys in simulated body fluids (SBFs) consisting of bovine serum albumin (BSA) and acidic SBFs (pH 5) using electrochemical methods. The addition of BSA significantly moves the open-circuit potential toward a more positive value and suppresses the corrosion reaction. The corrosion resistance under the open-circuit conditions in the SBFs with 1 g/L BSA is approximately twice that in the SBFs. A higher BSA concentration decreases the corrosion susceptibility. In addition, the acidic SBF results in a higher alloy dissolution rate. The possible mechanisms are discussed.

Fast degradation rates in the physiological environment constitute the main limitation for magnesium alloys used in biodegradable hard tissue implants. In this work, the corrosion behavior of AZ91 magnesium alloy in simulated body fluids (SBF) was systematically investigated to determine its performance in a physiological environment. The influence of the main constituent phases on the corrosion behavior was studied by in situ visual observation and scanning electron microscopy. Energy dispersive x-ray spectrometry and Fourier transfer infrared spectroscopy revealed that both calcium and magnesium phosphates are present in the corroded products besides magnesium oxide. Electrochemical methods including open circuit potential evolution and electrochemical impedance spectroscopy were used to investigate the mechanism. The corresponding electrode controlled processes and evolution of the corrosion products layer were discussed. The degradation rate after immersion in SBF for seven days was calculated from both the weight loss and hydrogen evolution methods.

Hydrogenated amorphous carbon (a-C:H) films were fabricated using mixed acetylene and argon plasma with various flow rate ratios of acetylene to argon. Raman scattering and x-ray photoelectron spectroscopy show that changing the flow rate ratios (FC2H2 to FAr) has a large impact on the structure of the films. Enhanced film hardness and reduced surface roughness were achieved at higher ratios attributable to the high ion flux and efficient etching by hydrogen. However, the film surface exposed to atomic hydrogen at a higher C2H2 flow rate becomes rougher. The sp3 content and film hardness also reach saturation combined with a fissile surface due to the high stress.

Nanosized materials have been widely applied in biomedical engineering due to their unique nano-effects. In this work, nano-TiO2 coatings and ZrO2 films were prepared using plasma technologies including plasma spraying and cathodic arc plasma deposition. The microstructure the coatings and films were assessed using TEM, SEM, and AFM. Their bioactivity and biocompatibility were evaluated using simulated body fluid soaking tests and cell culturing. Films and coatings with nanostructured surfaces can be obtained using plasma spraying and cathodic arc plasma deposition. The nanostructured surfaces can endow the films and coatings excellent bioactivity and biocompatibility. The UV-illuminated and hydrogen implanted nano-TiO2 coatings and ZrO2 films can induce bone-like apatite formation on their surfaces after immersion in a simulated body fluid for a certain period of time. The nano-TiO2 coating has better cytocompatibility than the micro-TiO2 coating, and the cytocompatibility can be improved by UV-illumination and hydrogen implantation. The bioactivity of the ZrO2 thin film deteriorates after thermal treated. The size of the particles on the surface of the film is thought to be one of the key factors responsible for the bioactivity.

The use of rutile-type titanium dioxide (TiO2) thin films as advanced gate dielectrics has been hampered by thermodynamic instability during the high deposition or annealing temperature of 800 °C. In this work, we demonstrate that rutile-type TiO2 thin films can be produced on p-type Si (100) at lower substrate temperature by means of bias-assisted cathodic arc deposition. The influence of the substrate bias on the microstructural and dielectric characteristics of the TiO2 thin films is investigated in detail. Our results show that by applying a suitable bias to the Si substrate, as-deposited rutile-type TiO2 thin films can be obtained at 450 °C. The permittivity of the materials increases significantly from 21 up to 76. The interfacial and electrical properties of TiO2/Si (100) are also improved. The effects and mechanism of the bias on the microstructural and dielectric characteristics are described.

ZnO films with orientations of (001), (110), and (100) were fabricated on silicon by different substrate biases at low temperature. Dynamic cathodoluminescence (CL) dependence on electron bombardment revealed unstable Zn-N bonding if N2 was used as a predecessor. CL under various accelerated voltages showed the possible energies of Zn-N. N-related photoluminescence (PL) at low temperature confirmed that nitrogen was released after annealing. These N-doping behaviors agreed to the theoretical calculation.

Low temperature oxidation is an essential process for thin-film transistors (TFT) used in active-matrix liquid crystal displays (AMLCD). However, low temperature oxidation gives rise to defects at SiO2/poly-SiGe interfaces. We have recently developed a novel plasma oxidation method for poly-SiGe materials. The poly-SiGe wafers are soaked in 0.1 Torr pure oxygen RF (Radio Frequency) plasma and isolated. That is, the sample voltage is the same as the sheath potential of the floating wall, which is always negative since electrons move faster than ions.The defects caused by ion impact can therefore be reduced. No heating is applied during oxidation, as the sample is heated slightly by the plasma. Under our conditions, the temperature is below 100°C even after oxidation for two hours. Depth profiles are acquired by AES and the oxide/substrate interface is examined by XPS. NMOS devices fabricated using this gate oxide show good characteristics.

Plasma ion implantation (PII) doping technique has been utilized to prepare a new lowdielectric constant (low k) material SiO(F,C). Fluorine and carbon were implanted into SiO2 films by CF4 PII using an ICP plasma reactor. The effective dielectric constant of the films was significantly reduced after PH doping. An analysis of a double layer model indicated that a high quality dielectric layer with a dielectric constant down to 2.8 can be achieved by an optimized PII process. Contrasting to other conventional low-k material techniques, PII process also improved bulk resistivity and electrical field breakdown strength. The improvement possibly resulted from adding carbon into the films. The etching effect of CF4 PII could be beneficial to planarization and gap filling of dielectric interlayer.

The thermal stability of thin CoSi2 films formed from four layered structures: Co/Si, TiN/Co/Si, Co/Ti/Si and TiN/Co/Ti/Si has been studied using four-point-probe (FPP), TEM and RBS/channeling. It is found that thermal instability can be influenced by the polycrystalline structure in CoSi2. Growing epitaxial CoSi2 film on Si (100) using TiN capping and Ti interfacial layers can improve the thermal stability of thin CoSi2 film.