bluuebunny/crossref_metadata_2025 huggingface dataset:
Biohydrometallurgy as a Remediation Strategy for Marine Sediments Contaminated by Heavy Metals
Authors: Beolchini F. , Dell’Anno A. , Rocchetti L. , Vegliò Francesco , Danovaro R.
Published: September 2009

This paper deals with biohydrometallurgy applied for the remediation of sediments contaminated by heavy metals. Both metal mobilization by bioleaching and metal stabilization by sulfate reducing bacteria stimulation have been investigated. In the first case, leaching experiments were performed with different microbial strains: i) autotrophic Fe/S-oxidizing bacteria, ii) heterotrophic Fe reducing bacteria, and iii) a mix of them. The highest extraction yields were 90% for Cu, Cd, Hg and Zn and were achieved with a consortium of the autotrophic and the heterotrophic strains. In the second case, anaerobic microcosm experiments were performed according to a full factorial experiment where the main factors were: i) acetate, ii) inoculum of alloctonous sulfate-reducing bacteria and iii) treatment time. Significant changes on metal partitioning were observed in all the investigated treatments: in particular, Cu, Pb and Zn concentrations in the mobile fraction were reduced and the ones in the oxidizable fraction significantly increased. Anaerobic processes where hypothesized to lead to the formation of metal sulfides, relatively stable and less bioavailable than mobile fractions. The obtained results open new perspectives for biohydrometallurgy applied in the context of remediation strategies for sediments contaminated by heavy metals.
Sulfidogenesis at Low pH by Acidophilic Bacteria and its Potential for the Selective Recovery of Transition Metals from Mine Waters
Authors: Johnson D. Barrie , Jameson E. , Rowe O.F. , Wakeman K. , Hallberg Kevin B.
Published: September 2009

Biosulfidogenesis (the generation of hydrogen sulfide by microorganisms) in acidic liquors was investigated using two metabolically-distinct bacteria. One was a novel acidophilic sulfate-reducing bacterium (isolate CL4) that grew at pH 3.0 and above using glycerol as electron donor, and the other was the type strain of Acidithiobacillus ferrooxidans which was grown at pH 2.5 using hydrogen (derived from dissolution of metallic iron) as electron donor and elemental sulfur as electron acceptor. Both bacteria were grown in pH-controlled bioreactors. Isolate CL4 mediated the selective precipitation of zinc in situ, while the At. ferrooxidans bioreactor operated as an off-line system, generating hydrogen sulfide that precipitated copper in a separate reaction vessel. The potential of using acidophilic sulfidogens for the selective recovery of metals from acidic waste streams is discussed.
Environmental Impact after 30 to 60 Years of Remediation: Microbial Investigation of Hard Coal Mining Dumps in Germany
Authors: Willscher Sabine , Starke Sophie , Felix Manfred
Published: September 2009

Important groups of microbes were investigated in three hard coal mining dumps in Saxonia/ Germany. In the particular dumps, different chemophysical and geochemical conditions are existing, depending on the kind of remediation up to six decades ago. Thiobacillus denitrificans, iron and sulfate reducers, and general aerobic heterotrophs and fungi were counted by MPN and CFU methods. Samples were taken from drilling cores in different depths out of the dumps, from seepage-, surface- and ground waters and from sediments. Similarities and significant differences were found between the microbial populations of the three dumps, depending on the appropriate environmental conditions. As a result, enhanced counts of T. denitrificans were detected at all three sites, originating from fertilizers (agricul-ture, gardens) and atmospheric precipitations. Sulfate reducers and aerobic heterotrophic microorganisms are suited indicators for the ongoing biogeochemical processes in the dumps
Population Dynamics of a Low-Grade Chalcopyrite Bioleaching Column
Authors: Mutch L.A. , Watling Helen R. , Watkin Elizabeth L.J.
Published: September 2009

Terminal Restriction Fragment Length Polymorphism (T-RFLP) was used to determine the diversity of the bacterial and archaeal populations in a bioleaching column charged with a low-grade chalcopyrite ore and operated at 50 oC. Differing populations were identified in the leachate and the column solids but there was not discernible effect in respect of location in the column.
Ex Situ Biostimulation of Hydrocarbon Degradation by Organic and Inorganic Amendments
Authors: Štyriaková Iveta , Hampl R. , Jech I.
Published: September 2009

To examine the effects of organic and inorganic amendments on the degradation of petroleum hydrocarbons, we conducted a pilot-scale experiment during the winter and summer periods. Soil samples were analyzed periodically to determine the soil gas amount of volatile organic compound, carbon dioxide flux, consumption of O2 and indigenous bacterial numbers during bioremediation. The initial level of the most contaminated site (10 070 mg hydrocarbon kg-1 soil) was reduced successively to 4 800 mg kg-1 after 4 months and to 1 400 mg kg -1 after 6 months in ex-situ amended soils. The hydrocarbon-degrading microbial populations increased during the treatment as also did soil respiration. Both aerobic and methanogenic conditions appeared to be important at these sites. Methane concentration (500-23 000 ppm) and CO2 production (800-17 000 ppm) varied with the extent of contamination. The bioventing system used in this study aerated a wide area of soil. It was concluded that N and P availability within the organic and inorganic nutrients limited the biodegradation of hydrocarbon contamination. By combination of organic and inorganic amendments a 86% removal efficiency was achieved. Nutrient diffusion varied within the 3 m high decontamination biopile but was sufficient to promote bacterial proliferation in all layers.
Existence of Ferrous Iron-Dependent Mercury Reducing Enzyme System in Sulfur-Grown A. Ferrooxidans MON-1 Cells
Authors: Sugio Tsuyoshi , Taha Taher M. , Negishi Atsunori , Takeuchi Fumiaki
Published: September 2009

Iron-grown Acidithiobacillus ferrooxidans MON-1 cells are highly resistant to organomercurial compounds as well as mercuric chloride (HgCl2). Existence of a novel Hg2+-reducing enzyme system, in which mercury resistant aa3-type cytochrome c oxidase catalyzes the reduction of Hg2+ with reduced mammalian cytochrome c or Fe2+ as an electron donor to give Hg0, has been shown in iron-grown MON-1 cells. There has been no reports on the mechanism of Hg2+ reduction by sulfur-grown A. ferrooxidans cells. The level of mercury resistance in sulfur-grown A. ferrooxidans MON-1 cells was compared with that of iron-grown MON-1 cells. Strain MON-1 was able to grow in 1% elemental sulfur medium (pH 2.5) containing 10 μM of Hg2+ or 0.2 μM phenylmercury acetate (PMA), suggesting that the levels of mercury resistance to inorganic and organic mercurial compounds are nearly the same in iron- and sulfur-grown MON-1 cells. Activity levels of Hg0 volatilization from HgCl2, PMA, and methylmercury chloride (MMC) were also nearly the same in iron- and sulfur-grown cells and these activities were markedly activated by 100 mM of Fe2+, but strongly inhibited by 1 mM of sodium cyanide, indicating that sulfur-grown MON-1 cells has the activity of ferrous iron-dependent mercury reducing enzyme system containing aa3-type cytochrome oxidase. aa3-type cytochrome c oxidase purified partially from sulfur-grown MON-1 cells showed both the iron oxidase and mercury reductase activities in the presence, but not in the absence, of rusticyanin and c-type cytochromes (Cyc1 and Cyc2) partially purified from iron-grown MON-1 cells.
Molecular and Morphological Characterization of Cultures from the Extreme Environmental Area of Copahue Volcano-Argentina
Authors: Giaveno Alejandra , Huergo J. , Lavalle L. , Sand Wolfgang , Donati Edgardo R.
Published: September 2009

This report describes the detection and identification of archaea in several sites located in the area of Copahue volcano, Neuquén province, Argentina by mean of different molecular techniques (PCR, DGGE, DNA sequencing and FISH). In order to study the archaea morphology, cultures were examined using different microscopic techniques (SEM, TEM, EFM and AFM). The corresponding archaea were identified as close relative or members of the genus Acidianus as well as other uncultured archaea clones showing a 93% of similarity to each others.
Evidence for Iron- and Sulfur-Oxidizing Bacteria and Archaea in a Currently Active Lignite Mining Area of Lusatia (Eastern Germany)
Authors: Siebert H.M. , Rohwerder Thore , Sand Wolfgang , Strzodka M. , Stahmann K.P.
Published: September 2009

The largest lignite mining area in Europe is located 150 km southeast of Berlin. Acidic lakes exist in this area, known to be caused by marcasite oxidation. Thirty-two samples from the open-pit brown coal-mine Jaenschwalde were analyzed for microorganisms. Cell numbers determined after separation from sand particles revealed concentrations of 102 to 107 microorganisms per g sample. In samples exposed to the air within an hour, up to 4x107 cells were counted. Measurement of metabolic activity by microcalorimetry showed for such samples up to 50 µW per g sand, whereas in heap samples (with low moisture) low or even no activity was measurable. DNA extraction was successful for 28 samples. In 26 samples microbial 16S rRNA genes were amplified by PCR. Acidithiobacillus ferrooxidans and At. thiooxidans specific amplificates were detected by nested PCR in 23 and 10 cases, respectively. A specific signal indicating Leptospirillum ferrooxidans was obtained with nine samples. Random samples were sequenced and showed 96 to 99 % identity with published data of all three species. Surprisingly, in four samples archaeal 16S rRNA genes were amplified by PCR. Sequencing of two samples showed 99 % identity with unidentified or uncultured archaea found in NCBI-databases. Molecular biology results for At. ferrooxidans as well as for At. thiooxidans were supported by successful isolations of pure cultures in 23 cases. Cultivation of the archaea failed so far. These data indicate that iron- and sulfur-oxidizing microorganisms occur at these sites in large numbers. If in addition the evidence for archaea can become verified, a screening for hot spots as the sites of their occurrence would become interesting.
Metallic Nanoparticles and Nanostructures for Bio-Applications
Authors: Zhang Jing Bo , Cheng L. , Yung L.Y.L. , Chua S.S. , Sze J.Y. , Zhu Shao Li , Ayi T.C. , Jeevaneswaran R.
Published: September 2009

This paper elaborates on approaches of synthesis of Au and Ag nanoparticles (NPs), deposition of colloid onto glass substrate and encapsulation of NPs with silicon dioxide (SiO2) thin shell. As one important bio application of metallic nanoparticles, both solution-based and substrate-based fluorescence enhancement tests are demonstrated.
Modeling of Cell Motion in Micro-Scale Hydrodynamic-Electrical Field
Authors: Ye Ting , Li Hua
Published: September 2009

A modeling of two-phase system is presented for investigation of the cell motion and deformation in the microchannel subject to the mechanical and electrical coupled forces. In order to evaluate the mechanical force developed by cell membrane, it is treated as an incompressible and elastic shell with uniform thickness capable of shearing and bending deformation. Due to the irregular and complex cell configuration after deformation, the Maxwell stress tensor (MST) method is successfully employed to analyze the dielectrophoretic force. The modified particle binary level set (MPBLS) method is presented to accurately track the moving interface between the two phases, which is vital for a modeling of two-phase system. Afterwards the modified SIMPLER coupled with SIMPLEC is used to numerically solve the incompressible Navier-Stokes equations governing the entire flow field. On basis of the series of methods, the motion and deformation of red blood cell (RBC) in the microchannel under the mechanical and electrical forces are simulated to demonstrate the deformation process and the moving trajectory of RBC. The present study is not only of great value for deeper understanding of some diseases caused by cell abnormality, but also of practical significance for cell manipulation and separation.
Micromachined Pressure Sensors on Optical Fiber Tip
Authors: Zhang X.M. , Yu M. , Nesson Silas , Bae H. , Christian A. , Liu Ai Qun
Published: September 2009

This paper reports the development of a miniature pressure sensor on the optical fiber tip for in vitro measurements of rodent intradiscal pressure. The sensor element is biocompatible and can be fabricated by simple, batch-fabrication methods in a non-cleanroom environment with good device-to-device uniformity. The fabricated sensor element has an outer diameter of only 366 μm, which is small enough to be inserted into the rodent discs without disrupting the structure or altering the intradiscal pressures. In the calibration, the sensor element exhibits a linear response to the applied pressure over the range of 0 - 70 kPa, with a sensitivity of 0.0206 μm/kPa and a resolution of 0.17 kPa.
Light-Driven Acoustic Band Gap Based on Metal Nanospheres
Authors: Wu Jiu Hui , Luk’yanchuk Boris , Chen Hua Ling , Liu Ai Qun
Published: September 2009

In this paper, light-driven acoustic band gap is presented by considering two metal nanospheres illuminated simultaneously by laser and acoustic waves. The interaction between the photonics and phonons is investigated through optical distribution force, van der Waals distribution force, and acoustic pressure upon these nanospheres. Based on the optical force and van der Waals force, the acoustic form functions for the metal nanoaggregates with different optical intensity are calculated, and the light-driven acoustics band gap at low frequency band has been found. It is shown that the band gap width can be widened with increasing the incident laser intensity, or by using proper metal materials and background media. This could provide potential applications in optical nanoswitches and acoustical filters.
Nano-Photonic & Electronic Structures Pattern and Fabrication
Authors: Teo Selin H.G. , Yu Ming Bin , Singh N. , Lo G.Q.
Published: September 2009

In this paper, techniques developed in the fabrication of nano-structures such as photonic gratings and vertical tube structures are presented for fabrication development that is applicable in the field of MEMS/NEMS technology – particularly for the optical integrated circuits [1] and sensor devices [2]. In such applications, not only is the resolution enhancements important, it is also often imperative that Critical Dimensions Uniformity (CDU) be kept as low as possible - since device performance often times scales directly with structural dimensions and its accuracy [3]. In this regard, techniques such as phase shift masking, off-axis illumination, optical proximity corrections, and also multiple patterning and resist ashing etc needs to be employed. This, not only increases the number and complexity of processing steps; it (at the same time) implicates other specifications such as illumination apertures, mask designs, optical proximity simulations, tool overlay tolerances etc. Coupled with additional non-CMOS requirements of atypical pattern shapes and densities, such as rings, horse-shoe shapes, sharp edges etc, a comprehensive study of the flexibilities involved with micro-lithography needs to be carried out for novel design prototyping. Here, the above described are illustrated, using examples of (i) a photonic gratings structure patterned with sharp edges, and (ii) a vertical-tube switch device structure, which are presented and discussed for their fabrication techniques and measurement results.
Bandstop Filters with Comb-Like Electromagnetic Bandgap Structures on CPW Stubs
Authors: Deng Zhong Liang , Huang J.M. , Ding B.H.
Published: September 2009

An ultra-wideband (UWB) band-stop filter (BSF) has been designed with flat responses at a selected frequency by cascading the unit electromagnetic bandgap (EBG) structures in this paper. The BSFs fabricated by the surface micromachining process have immense potential to compactness and low cost. The BSFs are constructed with comb-like EBG structures on a coplanar-waveguide (CPW) and have been investigated numerically. The simulation result of the BSF is demonstrated to have a good performance on its work band. It reveals a 20 dB stopband with a bandwidth of 6.8GHz. The pass-band insertion loss is less than 1.7dB.
Design and Characterization of a Fourier Transform Micro-Spectrometer
Authors: Wang Shou Hua , Yu Hong Bin , Chau Fook Siong , Tang X.S.
Published: September 2009

In this paper, we present a Fourier Transform micro-spectrometer which works based on a lamellar grating interferometer. The spectrometer model is electrostatically driven by parallel plate actuators which change the optical path difference (OPD) between movable grating facets and fixed ones. With a 200V input voltage, a maximum OPD of 48.7μm is achieved. The spectrum of a combined light source of a diode-pumped solid-state (DPSS) laser (λ=532.0nm) and a laser diode (λ=637.2nm) is experimentally acquired to demonstrate the performance of the model. The reconstructed spectrum displays two separate spectral peaks at 530.5nm and 635.2nm and the corresponding full-width at half-maximum (FWHM) resolutions are 9.8nm and 12.8nm respectively, indicating good wavelength accuracy and optical resolution.
Characterization and Optimization of Seals-Off for Very Low Pressure Sensors (VLPS) Fabricated by CMOS MEMS Process
Authors: Buyong Muhamad Ramdzan , Aziz Norazreen Abd , Majlis Burhanuddin Yeop
Published: September 2009

In the world of MEMS processing today, fabrications of membrane are performed using bulk micromachining (BMM). However these techniques not easiest to integrate with CMOS standard process due to not compatible of the processing flow. An attractive alternative deployment of surface micromachining (SMM). There is a trend to use surface micromachining to their advantage of simplicity in design and fabrication process compatibility. This paper presents process development of thin layer membrane for very low capacitive pressure sensor application. The structure of the membrane consists of parallel plate which both top and bottom electrodes were fixed at both sides. Utilizing CMOS MEMS process compatible fabrication of the thin layer membrane involved in three stages; i) hole opening etch, ii) sacrificial intermediate oxide release etch and iii) closing of etch holes. Therefore seals-off process characterization and optimization experiment are presented in this paper, will spur advancement in the development of a CMOS MEMS product for very low capacitive pressure sensor.
Materials Design and Analysis of Low-Power MEMS Microspeaker Using Magnetic Actuation Technology
Authors: Ayatollahi Fatimah Lina , Majlis Burhanuddin Yeop
Published: September 2009

This paper presents material properties of a micromachined mesoscopic acoustic speaker for hearing aid applications. The microspeaker has a single turn copper coil on a polyimide membrane, and an NdFeB permanent magnet beneath the membrane. The fields due to the permanent magnet were computed using FEMM. Then, forces based on the fields and on the coil driving current were computed. Finally, IntelliSuite was employed to simulate membrane displacements and stresses. The device, with a polyimide membrane diameter of 2.5 mm and thickness of 2 µm, consumes 3.4 mW to generate a sound pressure level of 108 dB in the human ear.
Parametric Study of Hot Embossing on Micro-Holes
Authors: Wu Cheng Hsien , Hung Chen Hao , Hu Ya Zhen
Published: September 2009

This report describes the application of hot embossing to produce parts with microstructure. An embossing machine, designed for microfabrication, was used to emboss PMMA and PC substrates. An insert with micro-holes of various diameters was applied in the hot embossing experiments. Effects of process parameters, such as embossing temperature, embossing force, embossing period and demolding temperature, on replicated heights were studied. Results show that replicated heights on smaller holes are smaller. Embossing temperature is the most important factor. Demolding temperature hardly affects the replication ability. Replicated heights increase with embossing period. The height can reach a very high value with a large enough embossing period.
Fabrication of Glucose Sensitive Actuator for DDS Micro Valve
Authors: Dzulkefli Nur Azrina , Bais Badariah , Majlis Burhanuddin Yeop
Published: September 2009

A glucose sensitive actuator for drug delivery system (DDS) consists of silicon boss, micro channel and outlet of the microvalve.The microchannel is essential to carry liquid samples in the system. In this paper, two types of microchannel, rectangular and trapezoidal, were fabricated using anisotropic etching of Deep-RIE and wet chemical etching using KOH solution, respectively. Fabrication were done for micro channels with cross sectional width of 100 -120µm width and length of 2 mm.
Analysis of Microelectromechanical Systems Using the Meshless Random Differential Quadrature Method
Authors: Mulay Shantanu , Li Hua
Published: September 2009

Several devices of microelectromechanical systems (MEMS) are analyzed in the presented work, using a novel numerical meshless method called the random differential quadrature (RDQ) method. The differential quadrature (DQ) is an effective derivative discretization technique but it requires all the field nodes to be arranged in a collinear manner with a pre-defined pattern. This limitation of the DQ method is overcome in the RDQ method using the interpolation function by the fixed reproducing kernel particle method (fixed RKPM). The RDQ method extends the applicability of the DQ method over a regular as well as an irregular domain discretized by uniform or randomly distributed field nodes. Due to the strong-form nature, RDQ method captures well the local high gradients. These features of the RDQ method enable it to efficiently solve the MEMS problems with different boundary conditions. In the presented work, several MEMS devices that are governed by the nonlinear electrostatic force are analyzed using the RDQ method, and their results are compared with the other simulation results presented in the existing literature. It is seen that the RDQ method effectively and accurately solves the MEMS devices problems.
Chain Length Dependence of SAMs-Assisted Copper Thermocompression Bonding
Authors: Jia Li , Hui Foo Qi , Fang Ang Xiao , Wei Jun , Wong C.C.
Published: September 2009

Direct metal thermocompression bonding is one of the key approaches used in creating interconnections in many heterogeneous devices. It has been reported that by coating a monolayer of alkanethiols on metallic surfaces such as gold or copper prior to bonding, the bonding temperature required for forming joints can be significantly reduced. In this paper, room temperature copper bonding is demonstrated successfully with the help of the organic monolayers. We also found that all alkanethiol- coated copper (CnH2n+1SH, at n = 6, 11, 18) exhibited superior bond strength (>25MPa) compared to that of the uncoated copper (<23MPa) at bonding temperatures from 25°C to 80°C. Further investigation shows that bond strength of copper joints increases with alkanethiol chain length (C18>C11>C6), which contradicts our previous finding in gold. We attribute this discrepancy to the difference in hardness between the two substrates.
Transfer Technology of Ferroelectric Films onto the Polymer Substrate for the Application of High Density Capacitor
Authors: Ichiki Masaaki , Maeda Ryutaro , Suga Tadatomo
Published: September 2009

High dielectric capacitors , that has around 1000 in dielectric constant, can be successfully formed by nanotransfer on non-heat-resisting substrates. PZT film could be released from the Si substrate and bonded onto the polymer one. The releasing characteristics have the relationships with the thickness of Pt layer. The formed PZT has perovskite structure and clear columnar texture.
Thermal Management and Alignment Strategies in MEMS Tunable Laser Packaging
Authors: Tao Ji Fang , Tamil Jonathan , Wu Jian , Xu Kun , Lin Jin Tong , Liu Ai Qun
Published: September 2009

A packaging architecture is developed for MEMS tunable laser (MEMS-TL). The hybrid integration of chips is realized under high accuracy thermal control and precise alignment. The thermal conductivity of the laser chip has been improved up to 60% by the proper substrate design of device and epi-down bonding method. Under the analysis of heat flux, we employ a thermo-electric cooler (TEC) to stabilize the temperature. The substrate is designed to accommodate gain chips with minimal active optical alignment, thus reducing the packaging cost. With this packaging scheme, the insertion loss is greatly induced less than 1 dB due to the advantages of horizontal and vertical alignment in optical fiber fastening and laser diode bonding.
Numerical Modeling of Spiral Micro-Mixers
Authors: Wee Yong Jun , Liu Ai Qun , Gan Ren Jian
Published: September 2009

Optimization of micro-mixing components is vital for efficient micro-electromechanical systems (MEMS) and lab-on-a-chips. In this area, it is ideal to have a universal micro-mixer design for general purpose multiple-phase fluidic mixing. Numerical methods to compute and analyze the mixing process in the spiral micro-mixer design are presented. This spiral design has also been found to be efficient for intra-droplet mixing as well as continuous particle separation by utilizing its attributing Dean flows. Analysis on the mixing performance of this design serves to present Archimedes’ spiral as a robust solution and exemplifies the effects of minute yet effective alterations to the design.
A Chip-Level Disposable Optofluidic Device for Biosensing
Authors: Liu H. , Zhang N. , Shiah Zi Chao , Zhou X.
Published: September 2009

This paper reports the fabrication, testing and characterization of an optofluidic sensor for biological sample detection at nanoscale. This biosensor consists of a two-layer structure fabricated by micro- and nanofabrication technology. A microchannel and its fluid connections have been patterned and formed in the silicon and glass. Gold nanoparticles have been fabricated by nanosphere lithography (NSL) on glass. The device has been tested and characterized by localized surface plasmon resonance (LSPR) experiment using a UV/vis spectrometer to obtain the absorbance as a function of wavelength. This device has innovatively integrated microfluidic and plasmonic technology in chip-level and the testing results show that the sensitivity is very high and suitable for biosensing. This device exhibits great potentials to yield ultra-sensitive bio-detection and precise control of ultra-small amount of bio-fluids.
Label-Free Protein Detection via Gold Nanoparticles and Localized Surface Plasmon Resonance
Authors: Zhu Shao Li , Zhang Jing Bo , Yue Lanry Yung Lin , Hartono Dany , Liu Ai Qun
Published: September 2009

Protein plays key role in cellular processes and diseases diagnosis [1-3]. This paper reports a label-free detection of proteins through localized surface plasmon resonance (LSPR) and realized Au nanoparticles (AuNPs) immobilized on glass slide. Glass slide is first sonicated with 5% v/v glassware detergent in ultrapure water for 30 mins, and then in ultrapure water for another 30 mins. A 5% v/v aminopropyltriethoxysilane (APTES) solution in ultrapure water is prepared and the glass slide is immersed in the 5% v/v APTES solution for 20 mins. The glass slide is sonicated for 60 mins in ultrapure water. The purpose of the sonication is to remove the multi-layers of APTES which are formed on the glass surface. The silanized glass slide is immersed in AuNPs solution for 40 mins. Finally, the protein solution is added on the surface of the slide. The surface absorption of proteins induces a significant difference of environmental refractive index around the AuNPs. The shift in the wavelength of the LSPR spectra is very sensitive to the change in the surface refractive index of the nanoparticles. The shifts in the LSPR spectra are primarily determined by the volatility and refractive indices of the protein species. In this paper, the LSPR-nanobiosensor is designed and fabricated. The LSPR band responses are measured by a real-time UV–vis spectrometer with a CCD array detector. The response time of the protein–LSPR spectrum is less than 3 seconds and the response is reversible and reproducible.
Study on Photocatalytic Degradation of Electroless Ni-P-TiO2 Composite Coating
Authors: Wu Yu Cheng , Zhang Zhi Ming , Huang Xin Min , Shan Chuan Li , Lin Zhi Ping
Published: September 2009

TiO2 shows a high efficiency in Photocatalysis, however, the recycling of TiO2 is difficult, composite coating is prepared by simultaneous elecroless deposition of NiP and TiO2 on substrates, surface topography and hardness of composite coating are investigated by metalloscope, SEM, EDS and Vickers microhardness; The relation between absorbence of methyl orange and time is researched by 723# spectrophotometer. The results show when TiO2 content in bath is 4g/L, plating speed is most fast and amount to 12.2μm/h, the photocatalytic effect is best. by comparing the microhardness of heat-treated compound coating and the Ni-P alloy coating, the maximum microhardness of the former appears in 500°C and achieves HV1180, and the latter appears in 400 °C and achieves HV950.
A Study on the Properties, Friction, Wear and Adhesion of HVOF Thermal Spray Coating of Micron Size Co-Alloy Powder
Authors: Cho Tong Yul , Yoon Jae Hong , Song Ki Oh , Joo Yun Kon , Cho Jae Young , Kang Jin Ho , Zhang Shi Hong , Chun Hui Gon , Kwon Sik Chul
Published: September 2009

High velocity oxygen fuel (HVOF) thermal spray coating of micron size (μ) T800 powder has been studied for the durability improvement of sliding machine components. The optimal coating process (OCP), surface properties, friction, wear behavior and adhesion of HVOF T800 coating have been investigated. The temperature dependence of friction coefficient and wear behavior have been studied at 25°C and at an elevated temperature 538°C (1,000°F) for the study of the temperature effects on FC and wear behaviors of the coating and for the application on high speed air bearing spindle which operates with no lubricants. The OCP was determined from the best surface properties of the 16 OCP searching coatings designed by the Taguchi experimental program of four spray parameters with three levels: a hydrogen flow rate (FR) of 38-42 FMR (1 FMR=12scfh=9.44×10-5 m/s), oxygen FR of 65-70 FMR and feed rate of 30 g/min, and a spray distance of 5 inch. Hardness, roughness and porosity observed from the 16 coatings were 560-640 Hv (5488-6272 MPa), 2.2-3.0 μm and 0.01-0.04% respectively. Friction coefficient (FC) decreased from 5.5-7.0 to 4.8-6.0 with increasing the sliding surface temperature from 25°C to 538°C because of the higher lubrication effect of Co oxide debris at the higher temperature. Wear trace of the coating and counter sliding SUS 304 surface decreased to more than a half with increasing the sliding surface temperature from 25°C to 538°C. Tensile bond strength (TBS) and tensile fracture location (TFL) of Ti64 / T800 were 8,770 psi (60.5 MPa) and near the middle of the coating respectively. Bond coat NiCr did not influence on the TBS of the coating. The adhesion between Ti64 substrate and T800 coating (Ti64/T800) was stronger than the cohesion strength 8,770 psi (60.5 MPa) of T800 coating. These showed that Ti64/T800 coating was recommendable for durability improvement coating on high speed spindle of Ti64.
Wear and Cutting Performance of Microdrills Coated Hard Film Deposited Using Closed Field Unbalanced Magnetron Sputter Ion Plating
Authors: Bao Ming Dong , Xu Xue Bo , He Jia Wen , Sun Hai Lin , Teer Dennis G.
Published: September 2009

Microdrills were deposited by Cr-N based and TiN coatings using a magnetron sputter technique. A flexible printed circuit board was used to evaluate the drilling lives. SEM observation was employed to reveal the wear and local welding. A special pin-on-disc tester was designed to assess the interaction between coatings and against materials. Drilling test indicated that the number of drilling holes increased significantly when the minidrill was coated Cr-N based film than TiN. Failure model of microdrill was studied for cutting this copper rich printed circuit board. Results demonstrated that welding produced between TiN coating and rich copper counter material, but welding did not occur between Cr-N based film and copper material.
Electroless Ni-Co-P Coatings on Sintered Nd-Fe-B Magnets with Improved Corrosion Resistance
Authors: Ma Tian Yu , Ying Hua Gen , Yan Mi
Published: September 2009

Electroless Ni-Co-P coatings have been deposited on sintered Nd-Fe-B permanent magnets by optimizing the bath composition and operating conditions. The corrosion resistance of coated Nd-Fe-B magnets was significantly improved and corresponding corrosion current density Icorr in 3.5 wt. % NaCl solution decreased by two orders of magnitude. Coated with 12μm-thick Ni-Co-P, Nd-Fe-B magnets possessed slight reduction in magnetic properties, with a modest loss of remanence (Br) by 3.9 % and coercivity (iHC) by 4.5 %.
Effect of Silicon Sol on Anodic Oxidation Film of Titanium Alloys
Authors: Liu Hui Cong , Zhu Li Qun , Li Wei Ping
Published: September 2009

In this paper, the anodic oxidation film was prepared in the 1~3mol/L NaAlO2 solution with and without silicon sol added. The film thickness, high temperature oxidation resistance, corrosion resistance, and SEM image, element composition in the film were investigated. The results show that there were obvious improvement in high temperature oxidation resistance and corrosion resistance of the film on titanium alloys after adding silicon sol into the NaAlO2 solution, and with the sol percentage in the solution increased, the foregoing protection abilities of the anodic oxidation film became better, while the film thickness was little affected with the sol percentage difference. The reason was discussed and the effective factor was the silicon composition and more even and compact image in the film.
A Study of the Structural, Mechanical and Tribological Properties of Ti-Al-N Coatings Post-Treated by Carbon Implantation
Authors: Shum P.W. , Zhou Zhi Feng , Li K.Y.
Published: September 2009

Carbon ion implantation has often been considered as an additional method to further improve the wear, corrosion and oxidation resistance of hard coatings on tools or machine parts. The present research investigates the effect of carbon implantation on the structural and mechanical properties of the sputter-deposited solid solution Ti-Al-N coatings. The carbon implantation was carried out by using metal vapour vacuum arc ion source (MEVVA) with solid cathode at energies of 5 and 50 keV, and a dose of 6×1017 atoms cm-2. The mechanical and the microstructure properties of the implanted layer were identified by a variety of analytic techniques, such as nano-indentation, x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) etc. Additionally, the wear performance of the samples was evaluated by a typical ball-on-disk tribometer in dry conditions. The results showed that the coatings with high energy carbon implantation exhibited an enhanced hardness. The improved hardness could be attributed to the formation of TiC phase, as indicated in XPS. In the sliding tests, the coatings with the post-treatment of carbon implantation showed an improved tribological property in terms of friction coefficient and wear rate. The friction coefficient could be reduced from 0.6 to 0.1. The coatings had ten-fold better wear resistance than the coating without ion implantation.
Investigation of the Grinding Wheel Air Boundary Layer Flow
Authors: Wu H. , Morgan Michael N. , Lin Bin
Published: September 2009

The boundary layer of air rotating with the grinding wheel can result in fluid starvation in the contact region. The boundary layer acts a barrier to fluid penetration and prevents fluid reaching the contact region and the fluid is deflected elsewhere. Such a situation is inefficient and wasteful. This work reports on an investigation of the air boundary layer aimed at increasing understanding of boundary layer for development of improved fluid delivery systems. The work reported focuses on the outcomes of experimental tests using the Laser Doppler Anemometry technique. Three velocity components of the air flow around the periphery of a rotating grinding wheel were measured for a range of wheel speeds. The contour distribution of the velocity and the turbulent distribution of velocity clearly show the air flow motion around the grinding wheel.
Wear of a Brazed Diamond Grinding Wheel with Diamond Grits Covered with Brazing Alloy
Authors: Huang Guo Qin , Chen Hei Jie , Huang Hui , Xu Xi Peng
Published: September 2009

The wear of a brazed diamond wheel with diamond grits covered with brazing alloy was investigated in comparison with a traditional brazed wheel whose grits were without covering. The two wheels were brazed in vacuum furnace and grits on one of them were overlaid with a thin layer of brazing alloy. The wear of the two wheels was tested through grinding of granite, during which grinding forces were measured and the wear states of diamond grits were observed. It is shown that grits covered with brazing alloy exhibited stronger self-sharpening ability and fracture resistance. Therefore, the wheel with covered diamonds performed lower grinding force and better wear performance.
Preparation of Brazed CBN Abrasive Tools Using Composite Fillers of AgCuTi Alloy and TiB2 Particles
Authors: Ding Wen Feng , Xu Jiu Hua , Chen Z.Z. , Su Hong Hua , Fu Yu Can
Published: September 2009

In order to dominate the wetting behavior of molten Ag-Cu-Ti alloy and control the brazing reaction at the joining interface, CBN abrasive grains were brazed using the composite filler of Ag-Cu-Ti alloy and 8 wt.% TiB2 particles. Ag-Cu-Ti alloy without reinforcing particles was also applied in the current investigation to compare with the composite filler. The characteristics of the joining interface and the reaction products were examined using optical microscope, scanning electron microscope, and X-ray diffraction instruments. Finally, the morphology of the CBN grains on the working surface of the brazed abrasive tools was observed. Results obtained show that the composite filler containing TiB2 particles distribute uniformly in the filler layer. Moreover, the interfacial chemical reaction of CBN grains and Ag-Cu-Ti alloy is restrained when TiB2 particles are added. The sharp edges of CBN grains are exposed fully due to the decreased wetting behavior of the composite filler.
Estimation Method of Grain-Height Distribution Based on the Working Surface Profile of Grinding Wheels
Authors: Sakamoto Haruhisa , Shimizu Shinji , Kashiwabara Shinichi , Tsubakiyama Hitoshi
Published: September 2009

To manage and control grinding process theoretically, the cutting-edge density should be quantified. In this study, the estimation method of the grain-height distribution, which is necessary to quantify the cutting-edge density, has been examined. From the results of simulation by modeling the grain distribution of a grinding wheel, the close correlation has been confirmed between the grain-height distribution and the peak-height distribution of the working surface profile. Based on this, the grain-height distribution can be estimated from the peak-height distribution by narrowing the width accompanied maintaining the total frequency. Since the estimated grain-height distribution agreed well to the distribution determined from the measured 3D-topography, the validity of the method has been confirmed.
Quantification Method of Cutting-Edge Density Considering Grain Distribution and Grinding Mechanism
Authors: Sakamoto Haruhisa , Tsubakiyama Hitoshi , Shimizu Shinji , Kashiwabara Shinichi
Published: September 2009

In this study, the quantification method of the cutting-edge density is proposed because of its close relation to the grinding mechanism. The cutting-edge density depends upon not only the grain distribution but also the thickness of effective cutting-edge layer. Therefore, the quantification of the cutting-edge density requires measuring not only the profile but also the grinding force. The thickness of effective cutting-edge layer can be determined based on the grain distribution, the grinding force and the stiffness of a grinding wheel. From applied result of the proposed method for the actual grinding process, the cutting-edge density and the effective cutting-edges layer is determined appropriately corresponding to the change in the working surface condition.
Research on Microscopic Grain-Workpiece Interaction in Grinding through Micro-Cutting Simulation, Part 2: Factorial Study
Authors: Yan Lan , Li Xue Kun , Jiang Feng , Zhou Zhi Xiong , Rong Yi Ming
Published: September 2009

The grinding process can be considered as micro-cutting processes with irregular abrasive grains on the surface of grinding wheel. Single grain cutting simulation of AISI D2 steel with a wide range of cutting parameters is carried out with AdvantEdgeTM. The effect of cutting parameters on cutting force, chip formation, material removal rate, and derived parameters such as the specific cutting force, critical depth of cut and shear angle is analyzed. The formation of chip, side burr and side flow is observed in the cutting zone. Material removal rate increases with the increase of depth of cut and cutting speed. Specific cutting force decreases with the increase of depth of cut resulting in size effect. The shear angle increases as the depth of cut and cutting speed increase. This factorial analysis of single grain cutting is adopted to facilitate the calculation of force consumption for each single abrasive grain in the grinding zone.
Estimation of Grinding Wheel Performance by Dressing Force Measurement
Authors: Mochida Yasushi , Kubo Akihiko , Tamaki Junichi , Nishioka Takao
Published: September 2009

Dressing force measuring equipment was developed and the performance of a single-point diamond dresser was examined focusing on the relationship between dressing force and grinding performance. It was found that a distinct relationship exists between dressing force and grinding performance, and that the sharp-edged single-point diamond dresser can control grinding performance with low dressing force. The single-point diamond dresser and multipoint diamond rotary dresser induce the same dressing force if their wear widths are equal.
Investigation of the Wear of the Pad Conditioner in Chemical Mechanical Polishing Process
Authors: Liao Yunn Shiuan , Yang C.T.
Published: September 2009

The pad surface will become grazed because of the accumulated debris in the chemical mechanical polishing (CMP) process. It results in the reduction of the wafer removal rate, and a pad conditioner or diamond disk must be frequently employed to refresh the pad surface. The wear behavior of a diamond with respect to its location, original relative protruded height and protruded shape on a diamond disk was investigated in this thesis. It was found from experimental data that the diamonds which were located outside, originally protruded more highly and with crest lines oriented upward wore faster. Accordingly, four suggestions were proposed to obtain the uniform diamond wear. They are: lowering the protruded heights of the outside diamonds, replacing the current flat substrate by a curved surface substrate, changing the diamond distribution on the disk from the current uniform one to a higher concentration around outside diameter, and orienting the diamonds such that the flats are protruded upward for the outside diamonds and the crest lines are projected upward for the inside diamonds. Experiment had verified that the pad conditioner with center-protruded substrate led to a stable and higher dressing rate.
The Computer-Controlled Chemical Polishing Techniques for Precision Optics
Authors: Xu Qiao , Wang Jian , Hou Jing
Published: September 2009

The computer-controlled chemical polishing (CCCP) techniques based on the Marangoni effect have been developed to manufacture precision optics on polished fused silica surface. In this study, we present the Marangoni confined chemical-etching process in which the material removal on optical surfaces can be accomplished by etching with buffered HF solution. The process shows stable characteristics and good repeatability while the etching depth can be controlled in the order of ten nanometers. We also present the experimental results of this technology for fabrication of phase corrector and continuous phase plate. Results show that the CCCP’s deterministic sub-aperture-polishing characteristics make it possible to correct the surface error and imprint complex phase structure with spatial scale-length of several millimeters onto optical surface.
Anisotropic Analysis on Processed Surface of KDP Single Crystals
Authors: Lu Chun Peng , Gao Hang , Wang Ben , Wang Qiang Guo , Teng Xiao Ji , Wang Bi Ling
Published: September 2009

Strong anisotropy of physical and mechanical properties of Potassium Dihydrogen Phosphate (KDP) crystals significantly affects surface quality during processing the samples. Different processing direction, along [100], [110], and [120] crystallographic orientations, are chosen on (001) crystal plane in order to evaluate the anisotropic characterizations on the processed surface. Scanning electronic microscopy (SEM) is employed to observe the machined surface damage, defects and profiles. At the same time, surface quality is measured by Zygo surface profiler to estimate the processed surface quality. The results show that the machined surfaces along three different orientations under the same processing conditions behave quite differently from each other. Strong anisotropy and complex slip system of KDP crystals lead to several different asymmetric damages on the machined surface. Surface roughness (Ra) values along [100] are the smallest, that along [120] are in average, and that along [110] are largest. Moreover, many illustrations are given to understand the anisotropic nature during processing, including slip system, mechanical properties during processing, and technical parameters, etc.
Effects of Horizontal Vibration Assistance on Surface Roughness in Magnetic Abrasive Finishing
Authors: Yin Shao Hui , Wang Yu , Huang Han , Zhu Yong Jian , Fan Yu Feng , Chen Yue
Published: September 2009

This paper investigates the effect of horizontal vibration assistance on surface roughness in magnetic abrasive finishing, and the material removal mechanism associated. The experiments on vibration-assisted finishing have clearly indicated that the improvement of surface roughness is mainly attributed to the cross-cutting effect of abrasives.
Processing of WC-Co Cemented Carbide Ball by EDR and RDP Lapping Modes
Authors: Yuan Ju Long , Yang Fan , Wang Zhi Wei , Tang Ke Feng , Chen Jia Jie
Published: September 2009

In order to get high precision balls used in oil exactor, Eccentric dual-rotating (EDR) V-groove lapping mode and Rotated dual-plates (RDP) lapping mode are applied for the batch processing of WC-Co cemented carbide balls of Φ35mm. After comparing two innovated modes, firstly EDR V-groove lapping mode is used in rough lapping stage for high efficiency, and then semi-finishing lapping stage, finishing lapping stage and polishing stage are carried out by RDP lapping mode. Through changing the processing parameters legitimately, including abrasive grain, adjustable rotating velocity and load, the rational course and parameters are defined, and WC-Co cemented carbide balls of Φ35mm satisfy the end products’ demand which means the sphericity is less than 1μm and the roughness of surface (Ra) is better than 50nm, so these balls can be applied in one-way hydraulic value used in oil exactor.