Abstract: Arrested precipitation methode used to synthesize CuInSe2 (CIS) nanocrystals were added to a hot solvent with organic capping ligands to control nanocrystal formation and growth. CIS thin films deposited onto Soda-Lima Glass (SLG) substrate by spray-coat, then selenized in Ar-atmosphere to form CIS thin films. PVs were made with power conversion efficiencies of 0.631% as-deposited and 0.846% after selenization, for Mo coated, under AM 1.5 illuminations. (XRD) and (EDX) it is evident that CIS have chalcopyrite structure as the major phase with a preferred orientation along (112) direction and Cu:In:Se nanocrystals is nearly 1:1:2 atomic ratio.
Abstract: In this article, the simulation of nanofluid flow in pipe and the behavior of different variables on nanofluid flow are presented. Al2O3-water of volume fraction of Al2O3 2 to 8% was considered as nanofluid for simulation. For the simulation the single phase approach is used to calculate viscosity, temperature difference on wall, Reynolds number, thermal conductivity and temperature throughout the pipe. The MATLAB code is employed to solve the flow in pipe using finite difference method. Finally a conclusion is made based on simulation, how the temperature of the nanofluid flow changed with the radial direction and its axial direction is reported. How thermal conductivity, temperature difference on wall, Reynolds number and the viscosity of the nanofluid changed with the length of the pipe is explained based on the present simulation. Also effects of volume fraction of nanoparticle, radius of pipe, outside temperature of wall, Reynolds number and turbulent flow on the heat flow through pipe.
Abstract: Thisis a conjecture which defines a new class of electrically conducting polymerthat chemically confines metals, ions or clusters within an electric potentialconstraining them to react in ways novel to chemistry. The polymers are planaron a planar surface and adhere as a ∏-bonded electron sheet to planar,electron-delocalized surfaces as in Fullerenes, graphene (both sides) andgraphite. The new polymers offer an extension of the properties of solid statePhysics into catalytic Chemistry. With the empirical formula typically C6X3where X is mostly chosen fromGroups 3A [B, Ga, In], 4A [Ge, Sn, Pb], 5A [N, P, As, Sb, Bi] and 6A [O, S, Se,Te] of the Periodic Table, or a mixture of these, the molecules can form thepolymer in Figure 1. Typically X= N, P, As, Sb, O, S, Se and Te. With an electric potential applied by theresearcher to the polymer in Figure 3, thisamounts to the creation of a new chemistry for each of the ions, clusters andneutral compounds of some 60 elements. Basically, this wide range of newcomplexes offers scientists access to fresh chemical opportunities when coatedonto Fullerenes, graphene and graphiteto force reactions not observed before and to explore both their chemical,medical and industrial implications.
Abstract: Thisstudy aimed for green synthesis of silver nanoparticles (Ag-NPs) from theantimicrobial crude extracted in chloroform: methanol(1:1 v/v) from the twobrown seaweeds Spatoglossum asperum and Hedophyllum sessileactive against two pathogenic bacteria (Xanthomonas axonopodis pv.citri and X. oryzae pv. oryzae) and a fungus Ustilaginoideavirens cause diseases in plants under in vitro assay. Crude extractsexhibit high antibacterial activity and low antifungal activity. Greensynthesized Ag-NPs showed very high antimicrobial properties on comparing itscrude extracts. Among the crudes, extract of Spatoglossum asperumexhibits higher bioactivity than the extract of Hedophyllum sessile butAg-NPs prepared from the extract of H. sessile possess very strongbioactivity over Ag-NPs of Spatoglossum asperum. Reduction of Ag-NPs wasconfirmed by UV spectra. FTIR data indicate that active groups related toterpenoids and phenols found in the crude extracts were responsible for thereduction of Ag-NPs. The XRD data showed that the pure three types of crystalsilver structure at 2θ values 32.51, 46.50 and 74.62 corresponding to 111, 200and 220 planes for silver, respectively. This study concludes that chloroform:methanol (1:1 v/v) extracts of Hedophyllum sessile and Spatoglossumasperum containing active groups related to terpenoids and phenols and theyare acting as reducing agents for green synthesis of silver nanoparticles whichare potential source for controlling the plant pathogens studied.
Abstract: DNA nanotechnology remains an activearea of research and advances have been reviewedrecently. DNAnanotechnology seeks to deploy molecules at an atomic level and on a small molecule scale. Other techniques in biophysics andbiochemistry do not need to address the issue of the true structure of thenucleic acids at an atomic level but, rather, at a macro-atomic level such asin genetics and in immunology, for example. Accordingly, DNA nanotechnology isperhaps uniquely dependent upon exact clarity in the secondary and tertiarystructures of the nucleic acids, as well as that can ever be achieved. Challengesinclude expanding the use of DNA in medicine, and the construction of detectorswith higher sensitivity for biological and chemical settings. Though increasinglycomplex architectures have been constructed, novel approaches to a greater rôlein biological computation and data storage remain important goals. Here arepertoire of structures for DNA at an atomic level is described which offers anew conjecture with which to move forward. The DNA double helix model facesmany problems which have become apparent in the 62 years of research inmolecular biology that have elapsed since it was formulated by Watson and Crick in 1953. Experimental evidence isset out seeking to show that the only truly side-by-side alternative, theparanemic model, accounts better for the wide range of phenomena otherwise inexplicable with the double helix model. This paranemic modelcan engage in a repertoire of structural options denied to the DNA double helixmodel. Without the requirement to postulate unwinding of the DNA strands, thenucleotide base sequence is immediately accessible to complementary DNAsequences to promote rapid detection of specific molecules in biological andmedical settings. Rapid switching between Watson-Crick and Hoogsteen basepairing and four-stranded structures can allow greater complexity in theconstruction of molecular switches and digital programming.
Abstract: High sensitiveand intelligence are the main function of the Magneto Rheological Fluids (MRF).In this research work, magneto rheological samples are prepared with twodifferent carrier oils (Honge and Castor) independently. Both the samples aremixed and prepared with same concentration of iron particles. In order toreduce the sedimentation fine lithium greaseis added as stabilizer for both samples. The flow properties are examined bycup and bob type rheometer. Then comparative study is made on theproperties like shear stress, strain, shear rate, dynamic viscosity, angularfrequency, storage modulus, loss modulus and loss factor.
Abstract: Abstract: Tool wear is one of theimportant phenomenon in the machining processes. In this article we areexplaining the effects of magnetorheological fluids in tool wear process. Inour investigation we used the Al alloy (Al 6061) as our test specimen, whichhas wide range of applications in aerospace industry. We attached ourmagnetorheological set up to the tool holder to conduct experiments. Weconducted different machining processes with and without our magnetorheologicalfluid setup, after observing the results it was found that the presence of magnetorheologicalfluid setup during machining processes minimises the tool wear and cuttingforces.
Abstract: The simulation of nanometric cutting of copper with diamondcutting tools, with the Molecular Dynamics method is considered. A 2D model of orthogonalnano-scale cutting is presented and the influence of the depth of cut and toolrake angle on chip morphology and cutting forces is investigated. For theanalysis, three different depths of cut, namely 10Å, 15Å and 20 Å and four toolrake angles, namely 0°, 10°, 20° and 30° are tested. Results indicate that with increasing depth of cut, cutting forces alsoincrease, while with increasing tool rake angle, cutting forces decrease.Furthermore, the effect of Lennard-Jones and Morse potentials on final resultsof the simulation is studied and discussed. The proposed model can besuccessfully used for the modeling and simulation of cutting operations thatcontinuum mechanics cannot be applied or experimental and measurementtechniques are subjected to limitations or it is difficult to be carried out.
Abstract: The main aim of this study is to synthesize magneto-rheological fluid in laboratory using silicon oil as carrier oil and it is mixed with variation in concentration of iron particles of size around 4-9 μm, fine lithium grease is used as surfactant. Prepared MR fluid is tested under plate and cone type rheometer for finding is rheological properties like shear stress, shear rate, shear viscosity, storage modulus and loss modulus.
Abstract: In this article, a p-n heterostructure diode was developed by incorporating the synthesised nanocomposite of CuS/PANI into the hallow network of ZnO thin film deposited on the glass substrate, which hitherto not reported. Analyses of the obtained heterostructure were carried out using XRD, FT-IR, UV-Visible and SEM. The penetration, bonding and the interaction of the nanocomposite with ZnO was investigated by the morphological, structural and optical studies. The obtained new hybrid material was found to have very good absorption in near IR region and results obtained supports that it may be used for different nanoelectronic devices.
Abstract: Current researches had shown that the electrical conductivity of most polymers depend on the method of its preparation and type of fillers. This research therefore aimed at studying the electrical properties of polyaniline carbon nanotubes nanocomposite prepared by hand mixing and decoration methods. The effect of preparation method on electrical properties of polyaniline containing Carbon Nanotubes (CNTs) and silver nanoparticles was studied. The formation of Ag NPs was confirmed by XRD. The AC-conductivity, dielectric permittivity (?’) and dielectric loss (?”) of (CNTs/PANI/Ag) nanocomposites have been measured in the temperature range from 298 to 433 K and frequency range from 10 to 100 kHz. The Ag-CNTs improved the electrical conductivity and dielectric properties of polyaniline. The electrical conductivity of the CNTs/Ag/PANI nanocomposite prepared by decoration method is higher than composites prepared by mixing method.
Abstract: The present study is an attempt to produce aluminum matrix nanocomposites using a certain aluminum alloy (which its melt has high fluidity) as a matrix material and reinforced with hard and stable fine (nano-sized) precipitates. Therefore, Al-Ti5-B1 master alloy and Al-Si alloy of high silicon content were proposed for preparation of such nanocomposites. Three nanocomposites were prepared by adding Al-Ti5-B1 of three different percentages (1, 2 and 3 wt. %) to the melt of aluminum alloy at 710°C for a holding time of 10 min and application of mechanical stirring at this temperature. Finally, the treated melt was squeeze cast. The microstructures were investigated using optical and scanning electron microscopes. Phases and different constituents were analyzed with the aid of EDX and XRD analyzers. The addition of Al-Ti5-B1 master alloy with any percentages (even 1 wt. %) to the melt of aluminum alloy, led to remarkable decrease of the matrix grain size. Moreover, many fine precipitates were detected within the Al-Si matrix such as TiAl3 phase in the form of flaky and blocky morphology and TiB2 phase in the nano-sized particles. These precipitates act as heterogeneous sites for nucleation during solidification. The addition of Al-Ti5-B1 master alloy to the Al-Si base metal led to remarkable increase in the average hardness. As the added percentage of Al-Ti5-B1 master alloy is increased, the average hardness value is increased. The average hardness of addition of 3 wt. % Al-Ti5-B1 master alloy reached 130 HV, which was almost twice as high as the hardness of the Al-Si base metal.
Abstract: The present paper reports on the rapid fabrication of Pd nanoparticles on glassy carbon electrode by eletrodeposition technique. It suggests that such film exhibits good catalytic activity and stability with respect to methanol oxidation in an alkaline media. It also suggests that the loading of the Pd nanoparticles on the substrate and therefore the effective catalytic area can be tuned by the deposition time used.
Abstract: Problem statement: Pipelined architecture is considered to be the most suitable for high-speed and high-resolution applications among varies Nyquist Analogue to Digital Converters (ADCs) in nowadays digital signal processing domain. But the pipeline power consumption is growing with the technology scaling. For a pipeline ADC with high speed and high resolution, the fore-end track and hold amplifier and residual amplifier occupies the most power consumption of the whole system, so new and novel methods is needed to lower the amplifier power consumption. Approach: Different from the traditional use of close-loop amplifier, open-loop amplifier is used as the first-stage residual amplifier, which greatly decreases the system power consumption and design difficulty. To correct the nonlinear error introduced by the open-loop amplifier, backend digital correction is applied. To validate the rationality and correctness of the method and confirm the design parameters, Verilog-A is used to build a behavioural model, Cadence simulation tool Spectre is used to get the result. Results: From the simulation result of the behavioural model, we get the Differential Nonlinearity (DNL) of the digitally backend correction ADC is -0.25?0.25, Integral Nonlinearity (INL) is -0.5?0.25, Spurious Free Dynamic Range (SFDR) is 77.8dB. The Total Harmonic Distortion (THD) of the system after correction is calculated to be 73.66dB, so the Effective Number of Bits (ENOB) of the is 11.78 bits. Conclusion: Digitally assisted backend correction is a novel approach to lower the power consumption of pipeline ADCs, which makes great significance in mixed signal system design. The use of open-loop amplifier instead of traditional closed-loop amplifier can effectively decrease the design difficulty and design process than before. Only the first stage residual amplifier is changed to open-loop in this article and this substitution can also be replicated in the track and hold circuit and the succeeding stages."
Abstract: Problem statement: Nanotechnology is already a large sector of industry and science research and it is expected to continue to grow at very fast rate. The determination of absolute measurements of length at the nanometer scale and below is very difficult and expensive. So the nanoscale metrology standard is needed. Approach: The laser-focused atomic deposition is a new way to establish nanoscale pitch standards. When the atoms pass though laser standing wave field, the atoms will change the moving trajectory and be focused to the node (or antinode) of the laser standing wave according to the detuning of laser frequency and atomic resonant frequency. Because of the period of the laser standing wave, laser mask will form the anologue of an array of cylindrical lense. If a substrate is positioned at the focal plane of this lens array, a periodic structure is depositing onto the surface. The period of this structure is ?/2 of laser. Results: In this letter, a 425 nm laser light standing wave is used to focus a beam of chromium atoms to fabricate the nanoscale pitch standards sample of 213±0.1 nm. The height was 4 nm. The (FWHM) width of 64±6 nm. Conclusion/Recommendations: The period of this structure is ?2 of laser, whose spatial period can be traced directly to an atomic transtition frequency and the uncertainty possibility is 10-5, which is fitted to be as the nanopitch standards"
Abstract: Problem statement: Biosynthesis of nanoparticles using fungal cells is a novel approach to develop biotechnological possess such as bioleaching and bioremediation. In the present study, an effort was made to investigate the effect of physio-chemical parameters on the silver nanoparticle formation with the fungus Chrysosporium tropicum Carmichael and Fusarium oxysporum Schltdl. Approach: The possibilities to manipulating the geometry of silver nanoparticles by altering the key growth parameters such as pH, temperature, concentrations and time have been explored. The effect of AgNO3 with the cell free extract of fungi and time, temperature, pH with the formation of silver has also been investigated. The presence of nanosilver has been carried out with the Micro-scan reader and has been confirmed by X-Rays Diffractometer (XRD). The micrographs of the silver nanoparticles have been evaluated through the Transmission Electron Microscope (TEM) and confirmed by Scanning Electron Microscope (SEM). The effect of concentrations with response to time, temperature and pH has studied with the help of Micro-scan reader and their microstructure analyzed by TEM and SEM. Results: It was observed that fungus C. tropicum and F. oxysporum Schltdl significantly activate the extra-cellular production of silver nanoparticles. The different sized and spherical shaped nanoparticles have been formed in different strains. With the increase in concentration, the absorbance increased with response to time (24-120h) and temperature. Significantly, the pH was found decreasing with the increase of absorbance. Conclusion: We presume that these changes initiate new geometry of nanosilver in the cell free solutions. These different shaped, sized and geometry of nanoparticles can be used in the field of medicine for drug formation and diseases diagnosis.
Abstract: Problem statement: Machines dynamic performance depends not only upon themechanical structure and components but also the drives and control system. However, the design ofthe machines is still at the nascent stage by working on an individual machine basis, hence lacksgeneric scientific approach and design guideline. Approach: Using computer models integrated drivesand control system to predict the dynamic performance of ultra-precision machine tools can helpmanufacturers substantially reduce the lead time and cost of developing new machine. This studyproposed a holistic integrated dynamic design and modeling approach, which supports analysis andoptimization of the overall machine dynamic performance at the early design stage. The modeling andsimulation process on an ultra-precision lathe machine tool is presented using the proposed approach.Results: Model of an ultra precision machine tool is established and used to predict the overallmachine performance of the configuration. Deformations of base and fixed sideways in motion arecalculated to demonstrate the valid of the method. Conclusion: Excellent accuracy on motiondeformation is achieved. The designed and implemented integrated time-domain dynamic analysis andmodeling system can predict the static and dynamic performance of ultra-precision machine tools,which can reduce the lead time and the cost of developing new machine.
Abstract: Problem statement: Barium Sulfate (BaSO4) is suitable for many applications because of its whiteness, inertness and high specific gravity. Approach: Nanoparticles of barium sulphate (BaSO4) have been synthesized from barium nitrate by precipitation method in the presence of water soluble organic polycarboxylic polymer as a modifying agent. Transmission electron microscopy, Scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray powder diffractometry were used to characterize the products as well as laser grainmeter. Results: The results indicate that spherical BaSO4 nanoparticles are obtained with poor crystalline and diameters ranging from 30-35 nm. Conclusion: The organic polycarboxylate shows as good modifier agent. So, this method can be employed to synthesize higher yield of BaSO4 nanoparticles.
Abstract: Problem statement: Single Point Diamond Turning (SPDT) is highly deterministic and versatile in producing various forms of precise optics. A typical example is the production of large offaxis aspheric mirrors and various infrared mirrors and mandrels. However, the fine periodical turning marks left in the surface critically limit its performance and they are difficult to be avoided for traditional polishing methods. Approach: This study introduced abrasive jet polishing to remove the periodical turning marks. Firstly the principle of abrasive jet polishing technique was described. Then combined with theoretical study, Computational Fluid Dynamics (CFD) simulation and process experiments, the mechanism of the material removal in abrasive jet polishing was analyzed. It was concluded that the wall shear stress of micro-abrasives is the main cause of material removal in this process. Based on this, abrasive jet polishing experiment was carried out on plane copper sample and the surface of Arrayed Waveguide Grating (AWG) which were machined after SPDT. Results: After polishing the periodical ripples on copper sample left by SPDT were removed completely and the Ra value of the sample decreases from 11nm to 3nm. In addition, the burrs and pits on the surface of AWG Mould after SPDT are removed successfully with this technique, which solves an intractable problem in manufacture area. Conclusion: In this experiment it was found that abrasive jet polishing technique has its inimitable advantages in removing the periodical turning marks and finishing the AWG mould and it will have a broad prospect of applications in modern precision manufacture area.
Abstract: Superparamagnetic Iron Oxide Nanoparticles (SPIONs) prepared by simplified coprecipitation were attractive as MRI contrast agents and drug carriers which could internally be manipulated under the influence of an external magnetic field and also cancer treatment due to additional hyperthermia effects. Problem statement: Macrophage and liver cells are potentially exposed to internal SPIONs, thus used for this cytotoxic tests for safety information of SPIONs. Approach: The SPIONs were physicochemically characterized by several instruments to ensure the production process. Cell viabilities, lipid peroxidation and nitric oxide produced after exposure to the SPIONs were conducted in normal macrophage and liver cells. Results: The approximately 15nm SPIONs produced had their structure confirmed by FTIR and X-ray diffraction and their magnetic properties probed by NMR. Macrophage and liver cells reacted differently to the SPIONs in dose- and time-dependent manners. Lipid peroxidation increased in macrophage cells, but not liver cells, after 24 h exposure to 100
Abstract: Problem statement: A portable X-ray elemental analyzer (total reflection X-ray fluorescence spectrometer) has been developed since 2006 and this spectrometer made it possible to perform ultra trace elemental determination. The intensity of scattered X-rays that become background noise in a spectrum is reduced with the improvement in surface accuracy of an X-ray reflector used in the portable spectrometer and therefore using an X-ray reflector with an ultra-precision specular surface can lead to further improvement in detection limits obtained by the portable spectrometer. Approach: In the present paper, a combination of electrolytic in process dressing (ELID) grinding and Magnetorheological Finishing (MRF) is applied to fabricating an X-ray reflector for the portable spectrometer. Magnetorheological finishing is used as final finishing after ELID grinding. Results: A peak to valley value of 107 nm and a root mean square value of 17 nm in a surface cross section with a length of 27 mm are obtained with the use of ELID grinding and MRF. Conclusion: X-ray reflectors having a large specular surface can be fabricated using a combination of ELID grinding and MRF. Using a grinding wheel containing diamond abrasive grains finer than those in the present paper in ELID grinding can lead to further improvement in surface accuracy of an X-ray reflector.
Abstract: Problem statement: Silicon Carbide (SiC) optical materials have become the first choice for mirrors in space optical systems and large ground-based optical systems due to their outstanding mechanical, physical and optical properties. Compared with traditional optical glasses, SiC optical materials are provided with the characteristics of high hardness and multiphase, which embarrass the high efficient fabrication of SiC mirrors with ultra-smooth surfaces and high precision. Approach: We choose some typical polishing parameters and conduct a series of experiments, trying to find out the relationship between polishing parameters and resulting surface roughness. The polishing parameters for Reaction Bonded Silicon Carbide (RB-SiC) are optimized from the analysis of these experiments. Then we can apply these parameters to the figuring process. Computer Controlled Optical Surfacing (CCOS) is a widely used deterministic polishing method and features in low-cost, high-precision and large flexibility. The basic theory and process of CCOS are given in detail. Then we employ CCOS in the ultra-precision machining of RB mirrors. Results: We polish a RB SiC sample with the optimized polishing parameters and a surface roughness better than 1nm (RMS) is obtained. A 475 mm diameter sphere RB-SiC mirror with a relative aperture of 1:1 is polished by CCOS and the surface error reduces to 0.175 λ (PV)/0.009λ(RMS) from 0.526 λ (RMS). Both results represent a very smooth surface and a very precise figure. Conclusion: The result proves the feasibility of the polishing technology and CCOS method. These works also accumulate experience for the manufacturing of aspheric SiC mirror.
Abstract: Problem statement: In this study a kind of soft Computer Numerical Control (soft-CNC) system for micro Electrochemical Machining (micro-ECM) based on RT-Linux platform is developed. Approach: Dual-kernel structure of System is adopted: Linux and RT-Linux are used to realize timesharing tasks and real-time tasks separately. Results: The CNC Graphical User Interface (GUI) is designed by Qt and runs on Linux core space. Based on the hard real-time facilities provided by RTLinux, the real-time tasks, including the gap detection task, gap adjustment task, interpolating task and other real-time control tasks are implemented. The Shared Memory (SHM) and RT-FIFO were adopted to construct the communication between the GUI and real-time tasks. Conclusion: A few experiments of various micro structures micro electrochemical milling on stainless steel are introduced to validate the performance of the system. The process and the results implied that the soft-CNC System is Real-time, stable and reasonable.
Abstract: Chemical Mechanical Polishing (CMP) has become the most widely used planarization technology in the semiconductor manufacturing process. Problem statement: Studying the Contact Forms in Wafer Chemical Mechanical Polishing. Approach: A series test on the abrasion behavior and the lubricating behavior was conducted and then the test results were investigated by the abrasion and lubrication theory. Results: By the test results and analysis, it showed that the Material Removal Rate (MRR) was mainly due to the interaction between abrasives and polishing slurry and the main material removal of wafer surfaces was two bodies abrasive wear under chemical interaction. By the Stribeck curves obtained, the lubrication state in CMP interface is belong to the boundary lubrication and the material removal is the process of bringing and removed of the chemical reaction boundary lubricating film on wafer surface constantly. Conclusion: By the analysis results, it was concluded that the contact form between the Wafer and the polishing pad is the solid-solid contact. These results will provide theoretical guide to further understand the material removal mechanism of in wafer CMP.
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