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151.
An inventory control problem for deteriorating items with back-ordering and financial considerations
This paper investigates the effects of time value of money and inflation on the optimal ordering policy in an inventory control system. We proposed an economic order quantity model to manage a perishable item over the finite horizon planning under which back-ordering and delayed payment are assumed. The demand and deterioration rates are constant. The present value of total cost during the planning horizon in this inventory system is modeled first, then a three phases solution procedure is proposed to derive the optimal order and shortage quantities, and the number of replenishment during the planning horizon. Finally, the proposed model is illustrated through numerical examples and the sensitivity analysis is reported to find some managerial insights. 相似文献
152.
Mohammadreza Tahriri Fathollah Moztarzadeh 《Applied biochemistry and biotechnology》2014,172(5):2465-2479
In this research, the novel three-dimensional (3D) porous scaffolds made of poly(lactic-co-glycolic acid) (PLGA)/nano-fluorohydroxyapatite (FHA) composite microspheres was prepared and characterize for potential bone repair applications. We employed a microsphere sintering method to produce 3D PLGA/nano-FHA scaffolds composite microspheres. The mechanical properties, pore size, and porosity of the composite scaffolds were controlled by varying parameters, such as sintering temperature, sintering time, and PLGA/nano-FHA ratio. The experimental results showed that the PLGA/nano-FHA (4:1) scaffold sintered at 90 °C for 2 h demonstrated the highest mechanical properties and an appropriate pore structure for bone tissue engineering applications. Furthermore, MTT assay and alkaline phosphatase activity (ALP activity) results ascertained that a general trend of increasing in cell viability was seen for PLGA/nano-FHA (4:1) scaffold sintered at 90 °C for 2 h by time with compared to control group. Eventually, obtained experimental results demonstrated PLGA/nano-FHA microsphere-sintered scaffold deserve attention utilizing for bone tissue engineering. 相似文献
153.
Central composite design with the help of multivariate curve resolution in loadability optimization of RP‐HPLC to scale‐up a binary mixture
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Mohammadreza Taheri Roudabeh Sadat Moazeni‐Pourasil Majid Sheikh‐Olia‐Lavasani Ahmad Karami Alireza Ghassempour 《Journal of separation science》2016,39(6):1031-1040
Chromatographic method development for preparative targets is a time‐consuming and subjective process. This can be particularly problematic because of the use of valuable samples for isolation and the large consumption of solvents in preparative scale. These processes could be improved by using statistical computations to save time, solvent and experimental efforts. Thus, contributed by ESI‐MS, after applying DryLab software to gain an overview of the most effective parameters in separation of synthesized celecoxib and its co‐eluted compounds, design of experiment software that relies on multivariate modeling as a chemometric approach was used to predict the optimized touching‐band overloading conditions by objective functions according to the relationship between selectivity and stationary phase properties. The loadability of the method was investigated on the analytical and semi‐preparative scales, and the performance of this chemometric approach was approved by peak shapes beside recovery and purity of products. 相似文献
154.
Ultrasound‐assisted supramolecular‐solvent‐based microextraction combined with high‐performance liquid chromatography for the analysis of chlorophenols in environmental water samples
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An efficient, inexpensive and environmentally benign ultrasound‐assisted supramolecular‐solvent‐based microextraction technique combined with high‐performance liquid chromatography was used for the determination of chlorophenols in environmental water samples. Different factors such as amount of decanoic acid, volume of tetrahydrofuran, pH of the sample, ultrasound time and ionic strength were investigated and optimized. The optimized extraction conditions were 60 mg decanoic acid, 1.5 mL tetrahydrofuran, 3 min ultrasound time, without salt addition. Under this condition, the extraction recoveries were 83.0–89.3 with preconcentration factors of 94–102. The calibration curves were linear from 5.0–400.0 ng/mL with square of the correlation coefficient higher than 0.9998 and the limits of detection were between 1.5–2.0 ng/mL. The values of intra‐ and inter‐day relative standard deviations were 3.2–6.0 and 7.3–8.0%, respectively. Analysis of different samples showed that the concentration of 2,5‐dichlorophenol in Babolrood river water was 80.6 ng/mL. 相似文献
155.
Essential oil (EO) compositions of flowers and fruits of Hypericum perforatum L. and Hypericum scabrum L. growing wild in Kashan, central Iran, were determined by simultaneous steam distillation-solvent extraction method and analysed using GC-MS technique. Analysis revealed 28 identified compounds for H. perforatum, with two main components being α-pinene (25.36%) and α-amorphene (12.12%). Thirty-five compounds were identified in H. scabrum L. representing 98.60% of the oil with α-pinene (70.21%) and p-mentha-1,5-dien-8-ol (2.89%) as main components. Some new compounds were found in significant quantities which were not found in other chemotypes. The antioxidant activities of the EOs evaluated for the first time in this study using β-carotene bleaching and DPPH assays seemed to be attributed directly to α-pinene contents in them. Antibacterial activities of both mentioned EOs were higher than that of their main constituent, α-pinene, against Staphylococcus aureus and Escherichia coli. 相似文献
156.
Mohammadreza Khanmohammadi Nahid Mashkuri Masumeh Rostami Amir Bagheri Garmarudi 《Journal of Analytical Chemistry》2012,67(4):330-334
Sodium perborate (SPB) and sodium percarbonate (SPC) are solid compounds which act as sources of H2O2 in solution for stain bleaching, being considered as oxidizing agents in washing powder. This research deals with the quantitative
determination of SPB and SPC by an analytical procedure based on attenuated total reflectance Fourier transform infrared spectrometry,
utilizing partial least squares for data processing in the 1600-800 cm−1 spectral region. The statistical parameters such as R
2, standard error of prediction and relative standard deviation have been evaluated, while number of factors, number of scans
and resolution were optimized. The standard deviation of method was 0.006 and 0.010 for SPC and SPB, respectively. 相似文献
157.
Kavosh Majlesi Mohammadreza Gholamhosseinzadeh Saghar Rezaienejad 《Journal of solution chemistry》2010,39(5):665-679
The main aim of this research is to study the complexation of molybdenum(VI) with methyliminodiacetic acid in NaClO4 aqueous solutions at pH = 6.00 and ionic strengths (0.1<I/mol⋅dm−3<1.0) at 25 °C by using potentiometric and UV spectrophotometric measurements in order to obtain thermodynamic stability constants
at I=0 mol⋅dm−3. A comparison with previous literature data was made for the stability constants, though few data were available. The stability
constants data have been analyzed and interpreted by using extended Debye-Hückel theory, specific ion interaction theory and
parabolic model. Finally it might be concluded that parabolic model applies better for this complexation reaction. 相似文献
158.
Extending to systems of hyperbolic-parabolic conservation laws results of Howard and Zumbrun for strictly parabolic systems, we show for viscous shock profiles of arbitrary amplitude and type that necessary spectral (Evans function) conditions for linearized stability established by Mascia and Zumbrun are also sufficient for linearized and nonlinear phase-asymptotic stability, yielding detailed pointwise estimates and sharp rates of convergence in Lp, 1?p?∞. 相似文献