Performance analysis of tool electrode prepared through laser sintering process during electrical discharge machining of titanium

The International Journal of Advanced Manufacturing Technology - It is of great significance for intelligent manufacturing to study condition monitoring and diagnosis methods to realize early...     

Nanoscale zerovalent iron-Sargassum swartzii biocomposites for the removal of malachite green from an aqueous solution

A novel nanoscale zerovalent iron-Sargassum swartzii (nZVI-SS) biocomposite was tested for its ability to remove malachite green from aqueous solutions. Batch equilibrium tests at different pH conditions showed that at pH 10, a maximum removal of 142.85 mg/g was observed according to Langmuir model. Involvement of various functional groups of the biosorbent in preferential biosorption of cationic dye was observed using Fourier transform infrared spectroscopy. Morphological changes occurring on the biocomposite materials were characterized using scanning electron microscopy. Furthermore, temperature and kinetic profiles during the biosorption process were also reported.     

Augmentation of band gap and photoemission in ZnO by Li doping

The monovalent impurity Lithium is chosen to dope with Zinc oxide (ZnO) in four concentrations by auto-combustion route. The influence of Li on the structural and optical properties of ZnO are discussed. The Li incorporation happens both as substitution and interstitial doping with an increase of grain size and the optical band gap of ZnO. The optical phonon modes are identified from Raman spectra that also gives information about the stress in the samples. The UV and visible emission characteristics of the samples are found from the fluorescence spectra. The origin of the visible emission is explained by defect chemistry. When Li lodges Zn site new acceptor levels of Li are created that causes the yellow emission that is absent in undoped ZnO. Li interstitial creates Zn interstitials that are responsible for blue emission. The green emission is explained as the outcome of the transition between Zn_i and oxygen vacancies.     

Insights into the formation of microporous materials by in situ X-ray scattering techniques

Here we demonstrate the power of in situ scattering techniques in the understanding of formation of nanoporous aluminosilicate and aluminophosphate materials. We utilised a number of X-ray techniques, in particular, in situ energy dispersive X-ray diffraction (EDXRD) and small angle and wide angle X-ray scattering (SAXS/WAXS) techniques for this purpose. The in situ SAXS measurements show the formation of homogeneous precursors in the size of ca. 10 nm, prior to the crystallization of LTA. The crystal size is estimated by fitting the SAXS patterns with an equation for a cubic particle, and it is revealed that the final crystal size of the LTA depends on the synthesis temperature. Whereas, the crystallisation of CoAlPO-5, occurs through the formation of poly-dispersed particles with an average size of the precursor particle of ca. 50 nm. Also shown the effect of temperature and structure directing organic cations on the production of CoAlPO-5 materials.     

Improved device performance based on crosslinking of poly (3-hexylthiophene)

Diode devices (glass/ITO/polymer/Al) have been fabricated using poly (3-hexylthiophene) (P3HT) crosslinked with two different biaryl crosslinkers. Crosslinking was performed by exposing the thin films with different wt% of crosslinker to UV irradiation and progress of crosslinking was monitored by IR spectroscopy. An increase in hole mobility of two orders of magnitude has been observed after crosslinking.     

Synthesis,spectral, thermal,and chelation potentials of polymeric hydrazone based on 2,4‐dihydroxy benzophenone

A chelating polymer, poly(2,4‐dihydroxy benzophenone hydrazone–formaldehyde) [poly(DHBPH–F)], was synthesized by the polycondensation of 2,4‐dihydroxy benzophenone hydrazone with formaldehyde in the presence of oxalic acid as a catalyst. Poly(DHBPH–F) was characterized by Fourier transform infrared and ¹H‐NMR spectral data. The molecular weight of the polymer was determined by gel permeation chromatography. Polychelates were obtained when the dimethylformamide solution of the polymer containing a few drops of ammonia was treated with an aqueous solution of metal ions. Elemental analysis of the polychelates indicated that the metal–ligand ratio was 1 : 2. The IR spectra of the polymer–metal complexes suggested that the metals were coordinated through the oxygen of the phenolic? OH group and the nitrogen of the azomethine group. The electron paramagnetic resonance and magnetic moment data indicated a square planar configuration for Cu(II) chelate and an octahedral structure for Ni(II) chelate. The thermogravimetric analysis, differential scanning calorimetry, and X‐ray diffraction data indicated that the incorporation of the metal ions significantly enhanced the degree of crystallinity. The polymerization initiation, electrical conductivity, and catalytic activity of the polychelates are discussed. Heavy‐metal ions [viz., Cu(II) and Ni(II)] were removed with this formaldehyde resin, and the metal‐ion uptake efficiency at different pH's, the nature and concentration of the electrolyte, and the reusability of the resin were also studied. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Secondary population implementation in multi-objective evolutionary algorithm for scheduling of FMS

Any practical implementation of any multi-objective evolutionary algorithm (MOEA) must include a secondary population composed of all Pareto-optimal solutions found during its search process. Such an implementation with an active participation of solutions from the secondary population into the generational population of the genetic cycle is expected to improve the effectiveness of the MOEA. In this work, two kinds of secondary population, one with set of non-dominated solutions and another with a set of inferior solutions, accrued out of the generation cycles are constructed, and with different combinations of feeding of solutions from these two secondary populations, seven different implementation schemes are designed with an aim of intensifying the convergence and diversification capabilities of the genetic process of MOEA. All the schemes were implemented in a genetic algorithm-based MOEA designed to solve the scheduling problem with dual objectives for a flexible manufacturing system and tested with common experimental data. The performances of the schemes are compared, and the most appropriate implementation scheme is proposed.     

Rotational abrasive flow finishing (R-AFF) process and its effects on finished surface topography

The present study focus on abrasive flow finishing (AFF), a process that finishes complex internal and external geometries with the help of viscoelastic abrasive medium, while keeping in mind its low finish and material removal rates (MRR). Researchers have often strived to improve finishing rate and MRR. As an attempt to overcome the said limitations, this paper discusses rotational abrasive flow finishing (R-AFF) process wherein complete tooling is externally rotated and the medium reciprocates with the help of hydraulic actuators. In this study, preliminary experiments are conducted on Al alloy and Al alloy/SiC metal matrix composites (MMCs) at different extrusion pressures, and medium compositions are employed for finding optimum conditions of the same for higher change in roughness (ΔR_a). The same optimum conditions are used to study the effect of workpiece rotational speed on (ΔR_a), material removal (MR), change in workpiece hardness and surface topology. It is noted that as the workpiece rotational speed increases from 2 to 10 RPM, the experimental helix angle decreases from 22° to 9° and the helical path length increases from 67 to 160 mm. Based on these findings the mechanism of material removal of matrix and reinforcement in MMC using R-AFF have been proposed. Here the matrix material is removed by micro-cutting and three methods of material removal mechanisms for reinforcement are also explained. The scientific logic behind finishing mechanism of matrix and reinforcement, cross hatch patterns, helical path directions, micro-scratch (μ-scratch) width and depth variation with size, orientation and support that active abrasive grain obtains from neighboring abrasives is derived from scanning electron microscopy micrographs. Finally this study establishes that R-AFF can produce 44% better ΔR_a and 81.8% more MR compared to the AFF process. Accordingly, R-AFF generates micro cross hatch pattern on the finished surface that can improve lubricant holding capabilities.     

Effects of the synthetic condition on the stability,particle size and redox chemistry of nanoporous CoAlPO-34

This study focuses on the effect of the synthetic conditions on the stability, particle size, redox chemistry of cobalt into the framework of CoAlPO-34. It seems that the most sufficient pH for the substitution of Co into the framework of CoAlPO-34 was pH around 7.5 when the as-synthesized bifunctional catalyst has the best redox property. The pH of the initial gel has strong effect on the particle size of CoAlPO-34. The substitution of cobalt and redox chemistry were determined by: EXAFS combined with XRD, XANES, IR. Stability of the nanoporous catalyst studied by in situ XRD were also reported.     

Behavior of decomposition of rifampicin in the presence of isoniazid in the pH range 1-3

The extent of decomposition of rifampicin in the presence of isoniazid was determined in the pH range 1-3 at 37°C in 50 min, the mean stomach residence time. With increase in pH, the degradation initially increased from pH 1 to 2 and then decreased, resulting in a bell-shaped pH-decomposition profile. This showed that rifampicin degraded in the presence of isoniazid to a higher extent at pH 2, the maximum pH in the fasting condition, under which antituberculosis fixed-dose combination (FDC) products are administered. At this pH and in 50 min, rifampicin decomposed by ~ 34%, while the fall of isoniazid was 10%. The extent of decomposition for the two drugs was also determined in marketed formulations, and the values ranged between 13-35% and 4-11%, respectively. The extents of decomposition at stomach residence times of 15 min and 3 h were 11.94% and 62.57%, respectively, for rifampicin and 4.78% and 11.12%, respectively, for isoniazid. The results show that quite an extensive loss of rifampicin and isoniazid can occur as a result of interaction between them in fasting pH conditions. This emphasizes that antituberculosis FDC formulations, which contain both drugs, should be designed in a manner that the interaction of the two drugs is prevented when the formulations are administered on an empty stomach.