Papers by Keyword: Characteristic

Abstract: Chitosan-Kappa Carrageenan (Chit-KC) hydrogel films have been made using a casting method with different compositions. This research aimed to investigate the effects of different compositions on the chemical, physical, and mechanical characteristics of the Chit-KC hydrogel films. The compositions of the kappa carrageenan in the Chit-KC films were 0%, 16.67%, 33.33%, 50.0%, and 100.0%. The films were characterized using FTIR, SEM, DTA-TGA, and XRD instruments to analyze their functional groups, morphology, thermal properties, and crystallinity. They were also tested for their solubility, swelling, water vapor permeability (WVP), and mechanical characteristics. The results revealed that the addition of kappa-carrageenan induced the formation of a polyelectrolyte complex. The polyelectrolyte complex caused an increase in swelling, crystallinity, and WVP values and a decrease in solubility, tensile strength, elongation, and elasticity. It also caused the formation of film layers and granules on the surface of the hydrogel film. The IR spectra exhibited that the Chit-KC hydrogel films contained O-H, C-H, C=O, S=O, C-O, and C-O-C groups. The DTA-TGA test results revealed that the film began decomposing at around 200°C and re-decomposing at 300°C.

Abstract: This article is aimed at evaluating newly synthesized HPMC/BW composite films, applied for preservation of seedless lime fruit. Factors influenced to formation of the films as well as characteristics of HPMC/BW edible composite films were researched and analyzed based on experimental results and previous studies. The HPMC/BW edible composite films were created based on the components included HPMC (5% w/v), Glycerol plasticizer (Gly-2% v/v), BW (5% w/v); Oleic Acid emulsifier (OA-1% v/v). Characteristics of the composite film were evaluated via the analytical techniques known as Sensory, Tensile Strength (TS), Elongation at Break (EB), ThermoGravimetric Analyzer (TGA), Scanning Electron Microscope (SEM), Fourier Transform InfraRed (FTIR). HPMC/BW composite films applied in preserving seedless limes. Evaluations of preservation processes were based on effects of characteristics such as Sensory evaluation, Respiratory intensity, Weight loss, Vitamin C content, Total acid of before and after fruits preservation.

Abstract: Geopolymer is known as an alkaline alumino-silicate material that has many potential advantages to replace for cement-based materials. Geopolymer is a green material with low or non-CO₂ emission technology, high strength and heat resistance, high chemical resistance, and low energy production. Geopolymer has synthesized from activated alumino-silicate resources in high alkaline conditions. After formed, the geopolymer samples are cured in different conditions such as room temperature, drying oven temperature (from 40°C to 150°C), high pressure and temperature conditions of autoclave equipment. In this study, the paper would like to introduce a new technique for curing the specimens. The geopolymer samples were cured in a microwave oven set by various regimes of curing time. After cured in microwave conditions, the samples were tested for engineering properties such as compressive strength (MPa), volumetric weight (kg/m³), and water absorption (kg/m³). This technology is a useful solution because of saving time for curing the geopolymer specimens in comparison with others (normally, it takes time for curing in 28 days). Microstructural characteristics of the fly ash-based geopolymer were analyzed and evaluated using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR).

Abstract: Indonesia coal ash is predicted to reach 10.8 million tons in the year 2020 but its utilization is still limited. In the last decade, coal ash has become a promising REY source candidate. To determine the potency of REY in Indonesia coal ash, information about element concentration and mineralogy of the ash is essential. In this study, coal ash samples were taken from Paiton-2, Pacitan, Rembang, and Tanjung Jati coal-fired power plants. Element content and mineralogy were analyzed using Inductive Couple Plasma Mass Spectroscopy/Atomic Emission Spectroscopy (ICP-MS/AES), X-Ray Diffractometer (XRD) and petrographic. The results showed that coal fly ash and bottom ash contains critical REY in the range of 38% to 41% with C_outlook larger than one. XRD analysis showed that both fly ash and bottom ash have similar mineral phases with slightly different concentrations. The mineral phase is dominated by amorphous glass, quartz, Fe-bearing minerals, and unburned carbon. The amorphous glass phase in fly ash is in the range of 23 to 34% while in bottom ash between 14 and 34%. Unburned carbon content in fly ash and bottom ashes are 7-13% and 7-19%, respectively. Fe-bearing mineral content in fly ash is 15-20% and bottom ash is 13-20%. In addition, Indonesia coal ash has a higher Heavy-REY enrichment factor than Light-REY. The Enrichment Factor of HREY in fly ash is as much as 1.3 times (in average) of the bottom ash.

Abstract: Bacterial cellulose (BC), produced by some bacteria has received attention because its high purity and robust characteristics enable its use in medicine and industry. This study aimed to screen bacteria capable of producing BC from fruits, and to optimize the BC production in both traditional YE yeast fermentation and Schramm and Hestrin (SH) media. The rice washing drainage without any pretreatment as the sole carbon source in the yeast medium was also investigated for BC production in both static and agitated cultures. The bacterial strain Li1 isolated from apple (Malus pumila) was identified as Komagataeibacter (Gluconacetobacter) nataicola based on 16S rDNA sequence analysis. K. nataicola Li1 cultured in a YE medium produced significantly more BC than that in a SH medium in the static culture. Moreover, the weight yields of dry BC films obtained from rice washing drainage and YE media in the static cultures were not significantly different. However, in the agitated culture, the weight yields of dry BC films were more significant in the YE medium than in rice washing drainage medium. In addition, the structure and properties of BC were determined using SEM, FTIR, DSC and XRD. This study shows that rice washing drainage can be used as the carbon source for BC production by K. nataicola Li1.

Abstract: Leakage is a persistent problem in buildings and some other structures, such as dam, bridge and water tower. For a long time, kinds of plugging agents have been developed successfully by modifying organic or inorganic materials. In this paper, the definition, classification and mechanism of plugging agent were introduced and explored in detail. Besides, some application principles and noteworthy matters in engineering were analyzed at well. Furthermore, based on the development of the construction industry in China, some viewpoints of the development prospects of plugging agent were proposed at last.

Abstract: To study the low temperature liquefaction characteristics of SF₆ for the operation security of electric equipments in cold area, the writer carries out the low temperature liquefaction test of SF₆ respectively in laboratory and outdoors by using SF₆ gas low temperature experimental apparatus. According to the results of the test and the Beattie-Bridgman SF₆ empirical formula, SF₆ gas state parameter curve is plotted and a concise practical SF₆ gas state parameter formula is got. This formula is more applicable to electric equipments outdoors. The results show that SF₆ gas is easier to liquefy in cold area, and the liquefaction temperature of SF₆ gas is in proportion to gas pressure. So the liquefaction temperature of electric equipments operated in cold area should not be higher than the lowest area temperature. Otherwise, measures must be taken to prevent SF₆ gas from liquefaction.

Abstract: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/functionalized graphene blends were prepared by solution blend method. The structure, thermal properties, thermal degradation and crystalline morphology were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG), and polarizing optical microscopy (POM) analyses. Experimental results indicated that FGO increase the intensity of diffraction peak. Small-sized PHBV spherulites were formed. FGO affects the crystallization behavior of PHBV as heterogeneous nucleation agent. FGO acts as an effective thermal barrier due to its large aspect ratio and thereby hinders the degradtion of PHBV.

Abstract: In high-strength steel hot forming, under the heating and quenching interaction, the material is oxidized and de-carbonized in the surface layer, forming a gradual change microstructure composed of ferrite, ferrite and martensite mixture and full martensite layers from surface to interior. The experiment enunciation: Form the table to ferrite, ferrite and martensite hybrid organization, completely martensite gradual change microstructure,and make the strength and rigidity of material one by one in order lower from inside to surface, ductility one by one in order increment in 22MnB5 for hot forming;Changes depends on the hot forming process temperature and the control of reheating furnace gas content protection, when oxygen levels of 5% protective gas, can better prevent oxidation and decarburization;Boron segregation in the grain boundary, solid solution strengthening, is a major cause of strength increase in ;The gradual change microstructure in outer big elongation properties, make the structure of the peak force is relatively flat, to reduce the peak impact force of structure, keep the structure of high energy absorption capacity;With lower temperature, the material yield strength rise rapidly,when the temperature is 650 °C, the yield strength at 950 °C was more than 3 times as much.

Abstract: Nanometer chitosan (nmCS) was obtained by ion exchange methodology, and the nanometer CS-Ag、CS-Ca and CS-Ag-Ca were prepared by introducing AgNO₃ and saturated CaCl₂ solution into the product obtained above. The structures of samples were characterized by IR, XRD, SEM etc. The properties of cruor and hemostasis were studied by biological experiment. The results showed that the characteristic absorption peaks at 1647 cm^-1 and 1560 cm^-1 in the IR spectra of modified chitosan were assigned to nanometer chitosan sodium salt. The XRD spectra showed the characteristics of crystal shape of Ag⁺ and Ca²⁺. The SEM showed that nanometer chitosan had a part of precipitate of Ag⁺ and the composite effect of nanometer CS-Ca was better. The properties of cruor and hemostasis of CS-Ag-Ca were superior to CS-Ag and CS-Ca, while the CS-Ag and CS-Ca were also had an advantage over CS.