Effect Of Liquid Environment Research Articles

Effect of liquid environment on adhesion strength of bioactive glass-based adhesives to bone

Glass Polyalkenoate Cements (GPCs) are composed of ionomeric glass having setting reaction with aqueous poly(acrylic) acid (PAA). The mechanical properties of GPCs are normally affected by various factors such as the concentration of the acid solution, the molar mass of the polyacid, and the powder:liquid ratio. A previous study using fracture testing of double cantilever beam specimens made with a GPC (GPC A) adhered to bovine bone showed that the mode I energy release rate decreased significantly when the specimens were prepared in a flooded liquid environment, simulating a worst-case surgical sternal closure application. The present study used pull-out and butt strength tests to determine the extent to which the adhesion to bovine bone could be improved in wet environments by using a more viscous adhesive (GPC B). The pull-out samples were prepared in both dry and flooded liquid environments and incubated in both humid and flooded liquid environments at 37 °C for two time periods: one and seven days. Overall, the pull-out strength of GPC B was found to be between 56% and 808% higher than GPC A, indicating that the more viscous formulation could mitigate the effects of the wet environment. The GPC B samples prepared and incubated in a flooded liquid environment (L-LI) had a significantly lower pull-out strength than all three other conditions: (1) when prepared in a dry environment and incubated in either a liquid (D-LI) or (2) humid environment (D-H), and (3) when prepared in a liquid environment and incubated in a humid one (L-H), which were all of similar strength. No significant difference in pull-out strength between the samples tested after 1 and 7 days of incubation was found indicating that robust adhesion strength was obtained rapidly. To further assess the adhesive strength for augmenting sternal closure, GPC B and bovine bone were used to create butt joints which were tested at strain rates typical of breathing and coughing. The tests revealed that GPC B's viscoelastic properties resulted in a higher butt joint strength for coughing loads compared to breathing. Overall, the results of the present study show that when the adhesives are expected to be subjected to a flooded liquid environment while they set, significant gains in adhesive strength can be obtained by using more viscous GPC adhesives.

Producing graphene nanosheets by pulsed laser ablation: Effects of liquid environment

Effects of liquid environment on the characteristics of graphene nanosheets produced by the laser ablation method have been studied experimentally. The fundamental wavelength of a pulsed Nd:YAG laser at 1064 nm with 7 ns pulse width and 5 Hz repetition rate was employed to irradiate a graphite target in distilled water, liquid nitrogen, alcohol, acetone, and two concentrations of cetyltrimethylammonium bromide. Produced carbon nanostructures were diagnosed using Ultraviolet-Visible-Near Infrared and Fourier transform infrared spectroscopy, x-ray diffraction, Raman spectroscopy, transmission electron microscopy, and field emission scanning electron microscope images. Results show that different carbon nanostructures such as carbon nanoparticles and fluorine, as well as graphene nanosheets were formed in various liquid environments. The size and morphology of nanostructures strongly depends on the liquid environments and, among these liquids, water is the most capable one to produce graphene nanosheets.

Experimental investigation of the effects of different liquid environments on the graphene oxide produced by laser ablation method

In this work, the effects of liquid environments on the characteristics and optical properties of carbon nanostructures – in particular, Graphene Oxide (GO) – prepared by pulsed laser ablation were studied experimentally. The second harmonic beam of a Q-switched Nd:YAG laser of 532 nm wavelength at 6 ns pulse width and 0.7 J/cm2 fluence was employed to irradiate the graphite target in liquid nitrogen, deionized water, and 0.01 M CTAB solution under the same initial experimental conditions. Produced nanostructures were characterized by Raman scattering spectrum, FE-SEM and TEM images, Photoluminescence, and UV–Vis-NIR spectrum. TEM and FE-SEM images show sheet-like morphology with few square micrometer area graphenes in all samples. Raman and UV–Vis-NIR analyses show that graphene is oxidized due to the presence of oxygen molecules in ablation environment. Results demonstrate that the graphene nanosheets produced in deionized water are multilayer, contains the largest sp2 domain size, the least defects and the lowest possibility of aggregation.

Effect of liquid environment on the titanium surface modification by laser ablation

The effect of liquid environment (de-ionized water and propanol) on surface, structural and mechanical properties of femtosecond laser ablated titanium has been investigated. For this purpose, Ti: sapphire laser (800nm, 30fs, 1kHz) has been employed, at a fluence of 3.6J/cm2 in ambient environments of de-ionized water, and propanol for various number of laser pulses i.e. 500, 1000, 1500 and 2000. The surface features, chemical composition, structural analysis and mechanical properties of irradiated targets have been evaluated by using Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X -ray Diffraction (XRD), Raman Spectroscopy and Nano-hardness tester. Various features like dendritic structures, globules, porous granular morphology, cones, crater, circular ripples and thermal stress cracking are observed at the ablated area after irradiation. These features are instigated by various thermal and chemical phenomena induced by laser heating at the solid–liquid interface. Decrease in nano-hardness observed in both ambient environments is attributable to the formation of hydrides after irradiation in both media.

The Effects of Liquid Environment on Ablation Efficiency and Morphology of Gold Nanoparticles Prepared by Laser Ablation Technique

Gold (Au) nanoparticles (NPs) were prepared by pulsed laser (Nd:YAG, 1064 nm) ablation of an individual target in deionized water (DIW), pure ethanol, and mixture of DIW and ethanol with different concentrations of ethanol. The effects of ambient liquid environment on ablation efficiency, stability, and size of Au NPs were experimentally investigated. The optical spectral characterization and morphological observations were determined by UV-Vis spectrophotometer and transmission electron microscopy, respectively. Particles are nearly spherical in shape in all liquid environments. The ablation experiment was initially performed by using DIW as the reference sample. The obtained Au NPs have an average particle size of about 18.71±7.50 nm. The comparison of the experimental results with the reference sample after a storage time of 48 h revealed that Au NPs in pure ethanol medium were not stable and exhibited much lower ablation efficiency and broader size distribution with an average particle size of 23.83±11.65 nm. Addition of ethanol with different volumes to the DIW significantly improved Au NPs properties in the mixture. The optimum ethanol concentration in the mixture was determined to be 70 vol%, which yielded the maximum ablation efficiency, rather narrow size distribution, and controllable size (12.43±8.10 nm) of Au NPs. A simple method for controlling the properties of Au NPs produced in the binary mixture of DIW-ethanol by laser ablation technique is presented.

Influence of liquid environment and bounding wall structure on fluid flow through carbon nanotubes

Flows of different fluids through single-walled carbon nanotubes (SWCNTs) with boundary walls having the perfect and defective graphene structures have been investigated by means of molecular dynamics (MD) simulations. It has been shown that the boundary wall structure has a very strong influence on not only an average fluid flow rate but also on shapes of trajectories of individual fluid atoms (molecules) and fluid centres of mass. The fluid flows through SWCNTs surrounded by different liquid environments have been also simulated and an influence of these environments on the average fluid flow rates have been studied. It has been revealed a strong dependence of the average fluid flow rate on a molecular polarity of fluids flowing through SWCNTs and those surrounding the tubes. It has been shown that, for multi-walled carbon nanotubes (MWCNTs), an effect of liquid environment on the fluid flow can be significantly suppressed.

The Effect of Liquid Environment on Composition, Colloidal Stability and Optical Properties of Nickel Nanoparticles Synthesized by Arc Discharge in Liquid

In this research, nickel nanoparticles were synthesized by arc discharge in different liquid media including deionized water, acetone, ethanol and methanol. Arc discharge is created with applying constant current 40 A between two nickel electrodes. Scanning electron microscopy (SEM), UV-visible spectroscopy and X-ray diffraction (XRD) were used for samples characterization. According to UV-visible spectra, nanoparticles synthesized in deionized water demonstrate metal oxide nanoparticles characteristic, but in organic media metallic nanoparticles were obtained. According to SEM images, the particle size of synthesized nanoparticles in deionized water, ethanol, methanol, and acetone are 25, 31, 38, and 45nm respectively. Also SEM images revealed spherical nanoparticles with broad size distributions in all media, but the narrowest size distribution was observed in deionized water. Furthermore, synthesized nanoparticles in deionized water sedimented after a week. On the other hand, synthesized nanoparticles in organic media were stabled for long periods of time without sedimentation. It is noticeable that the most stable nanoparticles were observed in acetone. Oxidation of nanoparticles in water and perfect colloidal stability in acetone could be explained via reaction of dissolved oxygen in water with nickel nanoparticles and dipole-dipole interaction of acetone molecules with nanoparticles respectively.

129 単結晶シリコンの疲労破壊に対する液体環境の影響の評価

129 単結晶シリコンの疲労破壊に対する液体環境の影響の評価

Sensitivity analysis of nonlinear vibration of AFM piezoelectric microcantilever in liquid

In this paper sensitivity analysis of nonlinear vibrating motion of atomic force microscope (AFM) piezoelectric microcantilever (MC) is performed in liquid environment. With respect to the importance of resonance amplitude and system nonlinearity in AFM application, sensitivity analysis of nonlinear vibrating motion is performed on these two parameters. The sensitivity analysis is carried out based on the Sobol statistical method. Piezoelectric MC has geometrical discontinuities due to presence of piezoelectric layer and tip. Regarding these discontinuities, non-uniform beam model is chosen for the dynamic modeling. Vibrating motion of the MC is modeled in AFM non-contact mode. The sensitivity analysis is performed to study how the effective parameters affect nonlinear vibrating motion in liquid. The sensitivity analysis of piezoelectric MC in liquid was compared with the one performed in air to better specify the effect of liquid environment on motion. The obtained results show that sensitivity of piezoelectric MC to nonlinearity of interaction force in air is greater than liquid and the sensitivity decreases with the increase of liquid density. With respect to the sensitivity analysis results, it can be concluded that the most effective geometrical parameters on nonlinearity in both air and liquid environments are thickness and length of piezoelectric layer and length of tip. The results of sensitivity analysis also show that the length of probe in liquid has a considerable effect on amplitude, whereas it has less effect on amplitude in air.

Effect of characteristics of media on cobalt and iron nanoparticles prepared by arc discharge method

Above a critical size, cobalt (Co) and iron (Fe) nanoparticles (NPs) aggregate due to magnetic dipole–dipole interaction into chains. In this paper, the effect of liquid environment on nucleation, growth and aggregation of Fe and Co nanoparticles is reported. The iron NPs were prepared by novel arc discharge method in ethylene glycol and 1-propanol and the cobalt NPs were prepared by that method in five liquid environments: ethylene glycol, 1-propanol, ethanol, methanol, and deionized water. SEM and FE-SEM observations were employed for morphology of the NPs. Meanwhile, in this case, the effect of media was discussed by considering the characteristics of the solution such as size, shape and dipole moment of its molecules. Preparation of Fe results shows that compared to 1-propanol a denser agglomeration can be seen among the NPs dispersed in ethylene glycol and the NPs possess a broader size distribution. Preparation of Co NPs in five solvent results if a solvent has large molecules with small dipole moment then the NPs will be larger in size. When three different amounts of surfactant PVP is added to prepared Fe nanofluid, it can be concluded that a low PVP content leads to more uniform NPs with rather clear boundaries.

The effects of liquid environments on the optical properties of linear carbon chains prepared by laser ablation generated plasmas

Linear carbon chains (LCCs) were successfully produced by laser generated plasmas in different solvents starting from graphite rods. An identification of the prepared carbon structures was carried out from the analysis of the UV–vis spectra. Moreover, a systematic analysis of the DFT computed structural and electronic response of both polyynic and cumulenic model molecules, as a function of the solvents with different polarity, was carried out. The comparison between the calculated UV–vis spectra of polyynes series with the experimental ones clearly indicates that polyynes are the dominant species produced by the ablation process. The optical limiting properties were investigated by the Z-scan method, using a nanosecond pulsed laser. Both the different solvents and the carbon chain length distribution have a driving role in the nonlinear optical response. Hence, the effect of the solvent polarity and acidity was taken into account to explain the nature of the optical limiting behaviour.

Effect of liquid environment on laser-induced backside wet etching of fused silica

In laser-induced backside wet etching (LIBWE), the liquid absorbent indirectly heats the transparent material, causing explosive phase change and cavitation. Accordingly, the hydrodynamics of the absorbing liquid, including the size of the liquid chamber, is strongly related to the ablation process. Because the hydrodynamics is dependent on the elastic deformation of the sample, the sample thickness also affects the performance of LIBWE. In this work, experimental analyses were performed to elucidate the hydrodynamics in LIBWE and the effect on the etch rate by varying the liquid chamber size and sample thickness. A KrF excimer laser was used to ablate fused silica samples in toluene and the etch rate was quantified using a scanning profilometer. Laser flash shadowgraphy and photodeflection probing techniques were employed for in situ measurement of the laser-induced hydrodynamics and displacement of the sample, respectively, with a time resolution of approximately nanoseconds. To directly observe the effect of increased liquid pressure on LIBWE, the liquid pressure on the etching spot was locally increased by an external shock wave and the etch results are examined. This study confirms that the photomechanical effects from the laser-induced bubble plays a key role in the LIBWE process, revealing a linear relationship between the etch rate the applied recoil momentum. However, the dependence of the etch rate on the chamber size and sample thickness could not be explained by the change in recoil momentum, i.e., by the bubble pressure. Instead, transient deformation of the sample by the pressure impact was estimated to be mainly responsible for the dependence.

Micro‐fabrication and monitoring of three‐dimensional microstructures based on laser‐induced thermoplastic formation

This article reports a novel laser-induced micro-fabrication method and its monitoring system for three-dimensional (3D) microstructures. The mechanism of the method is that a small zone of thermoplastic material melted by laser heating grows in liquid surrounding environment, solidifying into a convex microstructure, such as micro-dot or micro-pillar. A laser diode (808 nm) with maximum power output of 130 mW is used as power source, and a kind of paraffin mixed with stearic acid and paint serves as the thermoplastic material for 3D microstructure formation experiments. A light microscope system consisting of a charge-coupled device (CCD) and a computer is utilized to realize real-time observation of the micro-fabricating process. The distribution of local temperature rise on material surface created by laser irradiation is simulated. The effects of liquid environment on microstructure formation have been theoretically analyzed and experimentally studied. Experiments are further carried out to investigate the relationship between laser spot and fabricated microstructures. The results indicate that the widths of micro-dots or micro-pillars are mostly determined by the size of focal spot, and their heights increase with the enlargement of laser power density. With this method, a micro-dot array of Chinese characters meaning "China" has been successfully fabricated through computer programming. This method has the advantages of implementing direct, mask-less, real-time and inexpensive 3D microstructure fabrication. Therefore, it would be widely applied in the fields of micro/nano-technology for practical fabrication of different kinds of 3D microstructures.

The effect of liquid environment on size and aggregation of gold nanoparticles prepared by pulsed laser ablation

The effects of liquid environment on nucleation, growth and aggregation of gold nanoparticles were studied. Gold nanoparticles were prepared by pulsed laser ablation in deionised water with various concentrations of ethanol and also in pure ethanol. UV/visible extinction and TEM observations were employed for characterization of optical properties and particle sizes respectively. Preparation in water results in smaller size, shorter wavelength of maximum extinction and stable solution with an average size of 6 nm. Nanoparticles in solution with low concentration ethanol up to 20 vol% are very similar to those prepared in water. In the mixture of deionised water and 40 up to 80 vol% ethanol, wavelength of maximum extinction shows a red shift and mean size of nanoparticles was increased to 8.2 nm. Meanwhile, in this case, nanoparticles cross-linked each other and formed string type structures. In ethanol, TEM experiments show a mean size of 18 nm and strong aggregation of nanoparticles. The data were discussed qualitatively by considering effects of polarity of surrounding molecules on growth mechanism and aggregation. This study provided a technique to control size, cross-linking and aggregation of gold nanoparticles via changing the nature of liquid carrier medium.

Effect of the environment on the measured values of the adhesion of polyimide to silicon

We have studied the effects of liquid environments on the measured adhesion of PMDA-ODA polyimide to a silicon substrate by the blister and peel tests. The debonding pattern and adhesion strength were very sensitive to the liquid. For example, introducing pure methanol at the crack tip caused stick-slip debonding, with a high debonding angle, and severe plastic deformation of the polyimide film in blister tests, and greatly increased the adhesion strength in the peel test. The effects were progressively enhanced for water/methanol mixtures as the content of methanol increased, and for pure alcohols as the molecular size decreased. Evidently, as the wettability between the environment fluid and the surfaces involved improves, transport of the fluid to the crack tip region increases, allowing more diffusion of the fluid into the film, which causes a considerable decrease in its yield stress. Under these conditions, local plastic deformation and consequent blunting of the crack tip are facilitated, resulting in larger crack opening displacements, which requires more energy and increases the likelihood of unstable stick-slip propagation.

Effects of liquid environments on zirconia-toughened alumina

The structural changes which occur in zirconia-toughened alumina when aged in a range of liquid environments (distilled water, ethylene glycol solution and HCl at room temperature, and ethylene glycol solution at 80 °C) is described. The changes were monitored by X-ray diffraction, surface analysis, analysis of the ageing solutions and microstructural observations. It was found that HCl induced significant proportions of the zirconia particles in the zirconia-toughened alumina to transform from the tetragonal to the monoclinic crystal structure. This transformation was accompanied by microcracking which eventually led to macrocracking after long periods of ageing. The transformation is a consequence of the leaching of the yttrium from the zirconia particles, thereby reducing their stability.

Effects of liquid environments on zirconia-toughened alumina

The corrosion resistance of a zirconia-toughened alumina after prolonged exposure to a series of liquid environments is assessed. From the range of environments studied, only HCI caused a significant degradation in both strength and toughness. The mechanism of this deleterious behaviour was the transformation of the tetragonal zirconia particles to the monoclinic polymorph at the surface. The mechanical properties were determined by both the monoclinic content and the depth of penetration of the HCl, and hence the depth of the monoclinic-containing surface layer, with the latter probably being more important.

Crystallite growth of platinum dispersed on graphitized carbon black: II. Effect of liquid environment

The effect of various liquids on the growth of platinum crystallites dispersed on graphitized carbon has been determined from electrochemical surface area measurements. Although significant crystallite growth was not observed on exposure to hydrogen gas at temperatures less than 600 °C, rapid growth occurred below 200 °C in the presence of a liquid environment. Crystallite growth rates were independent of the platinum content on the catalyst and of the electrode potential. Furthermore, the nature of the liquid environment did not appear to have an influence on the rate of Pt crystallite surface area loss. When fitted to a simple power law, the order of the rate process lay between 11 and 13 and the activation energy was 21 kcal/mole. The implications of these experimental results are discussed with reference to recent theoretical models for the mechanism of crystallite growth. It is concluded that the evidence strongly suggests that two-dimensional Ostwald ripening (the migration of platinum atoms on the carbon surface) is the process whereby platinum is transferred from one crystallite to another, producing a decrease in the Pt crystallite density and surface area.