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The effect of changing injection temperature on some mechanical and morphological properties for polypropylene material (PP)

Abstract

This is a study of a medical injection factory-Babylon carried out in order to achieve proper mechanical and morphological properties, PP has been injection molded by using cold runner injection molding machine with temperature variation (198, 200, 203……220°C) for ten samples. The physical and mechanical properties of PP product were examined. It has been found that the Shore hardness decreases linearly with injection molding temperature increasing. The tensile strength has a similar behavior to the hardness. However, it has been found that the MIF (Melt Index Flow) rates increases with the increase of injection molding temperature. The density of PP has been found for both virgin PP and the samples, it has been found that the density decreases with increasing operation temperature. FTIR (Fourier Transmission Infrared) spectra were taken for both samples with high and low operation temperature. Besides the SEM (Scanning Electronic Microscopy) test shows the difference in the morphology of the product surface and the PP product at high and low operation temperature. Moreover, for all these properties, the PP product exhibits good mechanical properties (hardness, tensile strength, density) for the samples produced at temperature lower than 207°C. While the physical properties such as MIF improved with injection temperature increasing, additionally, the SEM images show that the sample produced in low temperature have surface damage.

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Effect of the electrodeposition potential on the magnetic properties of FeCoNi films

Abstract

The effect of electrodeposition potential on the magnetic properties of the FeCoNi films has been reported in this paper. The FeCoNi electrodeposition was carried out from sulfate solution using potentiostatic technique. The obtained FeCoNi films were characterized by X-ray diffractometer (XRD), atomic absorption spectrometer (AAS) and vibrating sample magnetometer (VSM). It has been shown that the electrodeposition potential applied during the synthesis process determines the magnetic characteristics of FeCoNi films. The more negative potential is applied, the higher Ni content is in the FeCoNi alloy. At the same time, Co and Fe showed almost similar trend in which the content decreased with an increase in applied potential. The mean crystallite size of FeCoNi films was ranging from 11 nm to 15 nm. VSM evaluation indicated that the FeCoNi film is a ferromagnetic alloy with magnetic anisotropy. The high saturation magnetization of FeCoNi film was ranging from 86 A·m2/kg to 105 A·m2/kg. The film is a soft magnetic material which was revealed by a very low coercivity value in the range of 1.3 kA/m to 3.7 kA/m. Both the saturation magnetization and coercivity values decreased at a more negative electrodeposition potential.

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An effective selection process is the key to quality job positions occupation conditional for long-term competitiveness

Abstract

The need for adaptation to rapid changes in the business environment, both on the part of employees and employers, implies dealing with new challenges, acquisition of new knowledge and skills and assumption of new roles and responsibilities. The base for companies is the availability of qualified human resources, which is ensured by the human resource management department mainly through an effective process of employee selection. The paper is oriented at the analysis of the current state of focus of organizations operating in Slovakia on systematicity and complexity of the selection process, the existence of an effective internal labor market and the regularity of development of used selection tools in the context of technological progress and changes in labor market requirements in regions of Slovakia. Results of the survey on (n = 343) enterprises show a positive trend, an increase of more than 10 percent in the orientation towards improvement of the process of employee selection, but on the other side it also confirm an increase in disparities between individual regions of Slovakia, some regions (Eastern Slovakia) progress much slower than the developed ones (Bratislava).

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Effects of Al doping on defect behaviors of ZnO thin film as a photocatalyst

Abstract

Al doped ZnO (AZO) thin films were prepared on silica substrates by sol-gel method. The films showed a hexagonal wurtzite structure with a preferred orientation along c-axis. Suitable Al doping dramatically improved the crystal quality compared to the undoped ZnO films. Dependent on the Al dopant concentration, the diffraction peak of (0 0 2) plane in XRD spectra showed at first right-shifting and then left-shifting, which was attributed to the change in defect concentration induced by the Al dopant. Photocatalytic properties of the AZO film were characterized by degradation of methyl orange (MO) under simulated solar light. The transmittance of the films was enhanced by the Al doping, and the maximum transmittance of 80 % in the visible region was observed in the sample with Al concentration of 1.5 at.% (mole fraction). The film with 1.5 at.% Al doping achieved also maximum photocatalytic activity of 68.6 % under solar light. The changes in the film parameters can be attributed to the variation in defect concentration induced by different Al doping content.

Open access
Elimination of constraints in the production process of power equipment components and the analysis of the resulting benefits

Abstract

The article presents the results regarding the elimination of constraints in the production process of a power equipment subassembly, a boiler chamber, together with an analysis of the benefits resulting from this, both financial and non-financial. The significance of bottlenecks in the production process, ways of its identification and limitations - in general - are presented. The article is a case-study of an attempt to eliminate the bottleneck in the production process of the boiler chamber, which turned out to be the process of drilling and marking-off, and work stations representing these processes. In order to eliminate the limitation, it was decided to replace the existing tracing and drilling work with a numerically controlled device - a boring machine moved from the liquidated department.. As a result, labor-intensive, manual chambers marking-off and the process of drilling holes with a smaller diameter drill have been eliminated. A number of benefits has been demonstrated resulting from the elimination of the bottleneck in the process, first of all, it was possible to reduce the duration of the marking-off and drilling operations and reduce the costs of the boiler chamber production process.

Open access
Enhancement of Faraday rotation in defect modes of one-dimensional magnetophotonic crystals

Abstract

In this paper, employing of one-dimensional magnetophotonic crystals in infrared wavelengths range is considered. For this purpose, magnetophotonic multilayer structures, composed of magnetic defect layer surrounded by dielectric and MO Bragg mirrors, have been proposed. Ce:YIG with an optical thickness in the range of 0 to λs was used as a magnetic material. By using four by four transfer matrix method, the transmittance values and Faraday rotation (FR) angles of these structures were computed. The electric field distribution was obtained by Finite Element Method (FEM). By investigation of transmittance and FR angle of magnetophotonic crystals, it was possible to design the optimized structures with a rotation larger than 30 degrees and high transmittance. Such structures with a few micrometer thickness and fast magneto-optical (MO) responses have the potential to be used in MO devices like integrated photonic elements and sensors.

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Green synthesis and spectral analysis of surface encapsulated copper (II) oxide nanostructures

Abstract

Nanostructures of copper (II) oxide were synthesized through chemical reduction of copper (II) sulfate pentahydrate using phytochemicals present in leaf extracts of Leucas aspera. The crystalline phases and size were assessed by X-ray diffraction data analysis. From the Bragg reflection peaks, existence of monoclinic end-centered phase of copper (II) oxide along with presence of cubic primitive phase of copper (I) oxide and traces of cubic face centered lattices of zero valent copper was revealed. The three Raman active modes corresponding to CuO phase were identified in the sample with permissible merging of characteristic bands due to nanostructuring and organic capping. The surface topography measurement using field emission scanning electron microscope evidenced the occurrence of cylindrical rod shaped morphological structures along with a number of unshaped aggregates in the sample. The effective crystallite size and lattice strain were estimated from Williamson-Hall analysis of Bragg reflection data. Tauc plot analysis of UV-Vis-NIR absorption data in direct transition mode provided an estimation of band gap, viz. 1.83 eV and 2.06 eV respectively, for copper (II) oxide and copper (I) oxide. Thermal degradation study using thermogravimetric curve analysis could reveal the amount of moisture content, volatile components as well as the polymer capping over nanorods present in the sample. It could be seen that upon heating, inorganic core crystals undergo oxidation process and at temperature above 464 °C, the sample was found to be composed solely of inorganic crystallite phase of copper (II) oxide.

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Growth, characterization and optical properties of potassium iodide (KI) doped potassium hydrogen phthalate (KHP) single crystals for optoelectronic applications

Abstract

Potassium iodide (KI) doped potassium hydrogen phthalate (KHP) single crystals were grown by slow evaporation technique using millipore water as a solvent. The grown single crystals were analyzed by powder X-ray diffraction and the analysis confirmed that KI-doped KHP crystallizes in orthorhombic system with space group Pca21. The functional groups were identified by FT-IR technique which showed slight shift in vibrational frequencies, indicating inclusion of dopant into the crystal lattice. The UV-Vis spectral studies revealed the optical transparency of the doped crystals in the entire visible region. The optical band gap values were estimated from Tauc plots. Kurtz-Perry powder test was employed for second harmonic generation efficiency studies of the grown crystals.

Open access
Growth, electrical, thermal, mechanical and etching studies on 4-chloroanilinium hydrogen (2R, 3R)-tartrate monohydrate-an organic NLO single crystal

Abstract

An organic single crystal of 4-chloroanilinium hydrogen (2R,3R)-tartrate monohydrate (4CAHT) was grown by slow evaporation solution growth technique at room temperature. Single crystal XRD study confirmed that the crystal belongs to monoclinic system with the space group P21. Powder XRD analysis confirmed the crystalline nature of the compound. The presence of various functional groups in the compound was revealed by FT-IR analysis. UV studies showed the absence of absorption in the entire visible region. To determine the thermal stability of the grown crystals it was subjected to thermogravimetric and differential thermal analyses. Microhardness and etching studies were also carried out for the crystal. The powder second harmonic generation efficiency of 4CAHT was tested by Kurtz and Perry powder technique and the relative SHG efficiency of 4CAHT was found to be 1.44 times greater than that of standard KDP.

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Impact Tests of UHSS Steel Welded Joints Using the Drop - Tower Impact Drop Method

Abstract

The article characterizes the impact test method using Drop-Tower Impact Test with the registration of the value of force and energy of breaking. Based on sources, the possibilities and scope of the current application of this method were determined and the current state of knowledge on the results of these tests was reviewed. In order to determine the possibility of using the method in impact tests of high strength steel joints, investigations of hybrid PTA - GMA welding conditions on impact strength of joints of MART S1300QL steel were carried out. In particular, the influence of t8/5 cooling time on the impact strength of welded joints by the Drop - Tower Impact Test method was determined. It has been shown that the use of dropping machine with computer-based registration of breaking force and energy values was possible in the case of impact strength testing of UHSS welded joints and enabled precise analysis of the energy distribution dynamics absorbed by the tested.

Open access