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      • KCI등재

        A New Methanol-feeding Strategy for the Improved Production of β-galactosidase in High Cell-density Fed-batch Cultures of Pichia pastoris Mut+ Strains

        Amir Maghsoudi,Safoura Hosseini,Seyed Abbas Shojaosadati,Ebrahim Vasheghani-Farahani,Mohsen Nosrati,Ali Bahrami 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.1

        Developing novel methanol-feeding strategies for the improved production of heterologous proteins in high cell-density fed-batch cultures of Pichia pastoris has been of great interest during recent years. In this study, a recombinant P. pastoris strain (GS115/His+ Mut+) producing β-galactosidase (β-Gal) was used to investigate conventional feeding strategies and to develop a new strategy to increase the recombinant protein production during fedbatch cultures on methanol. Three types of conventional methanol-feeding strategies, including μ-stat, dissolved oxygen-stat (DO-stat) and constant methanol concentration were investigated and compared with respect to alcohol oxidase (AOX), formate dehydrogenase (FDH) and β-gal activities, and cell dry weight (CDW), methanol, and formaldehyde concentration variations during the production phase. Methanol feeding with μ-stat 0.025/h exhibited the highest β-gal activity. Supplementing ammonium and magnesium in μ-stat 0.025/h did not affect the cell growth or methanol or formaldehyde concentrations throughout the fermentation but did improved the maximum β-gal activity from 148.2 to 158.1 kU/mL. A new three-step methanol-feeding strategy was developed based on the results obtained from conventional feeding strategies, which started with μ-stat 0.025/ h for 5 h, then μ-stat 0.030/h, and finally, was switched to DO-stat when maintaining the DO above 20% air saturation became difficult. Implementation of this new feeding strategy resulted in a CDW of 107.2 ±0.7 g/L, AOX specific activity of 0.1890 ± 0.0030 U/mg CDW, and β-gal activity of 173.5 ± 2.1 kU/mL after 29 h of fermentation, which shows a 5.6, 29.1, and 15.7%increase in CDW, AOX, and β-gal activity, respectively,compared to that of μ-stat at 0.025/h.

      • KCI등재

        Application of numerical techniques to the recognition of structural controls on porphyry Cu mineralization: a case study of Dehaj area, Central Iran

        Habibkhah Narges,Hassani Hossein,Maghsoudi Abbas,Honarmand Mehdi 한국자원공학회 2020 Geosystem engineering Vol.23 No.3

        This paper endeavours to evaluate the structural controls of porphyry copper mineralization in Dehaj area, Central Iran, using numerical techniques, an aim for which the various data types including the location of mineral deposits, stream sediment geochemical data and faults were employed. Initially, classical statistics and the concentration-area (C-A) fractal methods were applied to identify mineralization-related geochemical anomalies, revealing the superiority of fractal technique over the traditional methods employed. In addition, a rose diagram portraying the distribution of mineral locations was compared to the distribution and trends of faults using fractal and fry analyses, showing that the spatial pattern of porphyry copper deposits is closely linked to NW- and E-trending faults. In other words, the aforementioned structural trends were plausibly the chief geographical directions controlling the mineralization. The results of this study suggest that NW- and E-trending faults have plausibly operated as corridors for the transportation of ore-bearing fluids.

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        Investigating the capabilities of multispectral remote sensors data to map alteration zones in the Abhar area, NW Iran

        Bahrami Yousef,Hassani Hossein,Maghsoudi Abbas 한국자원공학회 2021 Geosystem engineering Vol.24 No.1

        Economic mineralization is often associated with alterations that are identifiable by remote sensing coupled geological analysis. The present paper aims to investigate the capabilities of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Landsat-8 and Sentinel-2 data to map iron oxide and hydrothermally alteration zones in the Abhar area, NW Iran. To achieve this goal, the principal component analysis (PCA) and two machine learning methods including support vector machine (SVM) and artificial neural network (ANN) were employed. PCA method was carried out on four bands of all data and then the appropriate principal components were selected to map alterations. Due to the high precision of ASTER data within the short-wave infrared range, these data results are more satisfactory compared with Landsat-8 and Sentinel-2 sensors in detecting hydrothermally alterations through the PCA technique. Based on the obtained maps, the performance of all data types was approximately similar in the detection of iron oxide zones. Our desired data were classified by two methods of SVM and ANN. The results of these algorithms were presented as confusion matrix. According to these results, for hydrothermally alterations, ASTER data showed better performance in both SVM and ANN than other datasets by gaining values greater than 90%. These data did not perform well in the iron oxide zones detection, while Landsat-8 and Sentinel-2 have been more successful. For iron oxide, based on confusion matrix, Landsat-8 data have obtained the values of 78% and 79% through SVM and ANN algorithms, respectively, and also Sentinel-2 has acquired the values of 88.11% and 90.55% via SVM and ANN, respectively. Therefore, to map iron oxide zones, Sentinel-2 data are more favorable than Landsat-8 data. In addition, the ANN algorithm in ASTER data has represented the highest overall accuracy and Kappa coefficient with the values of 88.73% and 0.8453, respectively.

      • KCI등재

        Assessment of prospective areas for providing the geochemical anomaly maps of lead and zinc in Parkam district, Kerman, Iran

        Seyyed Saeed Ghannadpour,Ardeshir Hezarkhani,Abbas Maghsoudi,Ehsan Farahbakhsh 한국지질과학협의회 2015 Geosciences Journal Vol.19 No.3

        There are several statistical methodologies presented for separating anomalous values from background leading to determination of anomalous areas. These methods range from simple approaches to complicated ones and include nonstructural and structural methods, subtraction separation method and so on. Structural methods take the sampling locations and their spatial relation into account for estimating the anomalous areas. The U-statistic method is one of the most important structural methods. It considers the location of samples and carries out the statistical analysis of the data without judging from a geochemical point of view and tries to separate subpopulations and also to determine anomalous areas. In the present study, several nonstructural methods including assessment of threshold based on median and standard deviation, median absolute deviation (MAD) and P.N product are used and U-statistic is considered as structural method to assess prospective areas of Parkam district. Results show that MAD method reduced background well and P.N method increased correlation of points. However, U-statistic method plays the role of both mentioned advantages meaning in addition to reducing outlier data effect, it regularizes anomalous values and also their dispersion is reduced significantly. It is possible to determine anomaly areas according to anomalous samples positioning so that denser areas are more important. Finally, lithogeochemical map of study area is provided for lead and zinc.

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