741 research outputs found
Investigation of Interaction Hydrogen Sulfide with (5,0) and (5,5) Single-Wall Carbon Nanotubes by DFT Method
In the present study the interaction of Hydrogen Sulfide with inside and outside single-wall carbon
nanotube of (5,0) and (5,5) was investigated. This study was conducted using DFT at B3LYP/6-31G* level
of theory. Computational calculations were performed in the gaseous phase in Gaussian 09. The geometry
of all molecules under investigation was determined by optimizing all geometrical variables without any
symmetry constraints. The harmonic frequencies were computed from analytical derivatives for all species
in order to define the minimum-energy structures. The adsorption energies, the thermodynamic properties,
HOMO-LUMO energy gaps and partial charges of the interacting atoms were also studied during two rotation
kinds of H2S molecules vertical and horizontal to the main axes of nanotube.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3516
Application of queuing theory in production-inventory optimization
This paper presents a mathematical model for an inventory control system in which customers' demands and suppliers' service time are considered as stochastic parameters. The proposed problem is solved through queuing theory for a single item. In this case, transitional probabilities are calculated in steady state. Afterward, the model is extended to the case of multi-item inventory systems. Then, to deal with the complexity of this problem, a new heuristic algorithm is developed. Finally, the presented bi-level inventory-queuing model is implemented as a case study in Electroestil Company
A new methodology to study customer electrocardiogram using RFM analysis and clustering
One of the primary issues on marketing planning is to know the customer's behavioral trends. A customer's purchasing interest may fluctuate for different reasons and it is important to find the declining or increasing trends whenever they happen. It is important to study these fluctuations to improve customer relationships. There are different methods to increase the customer's willingness such as planning good promotions, an increase on advertisement, etc. This paper proposes a new methodology to measure customer's behavioral trends called customer electrocardiogram. The proposed model of this paper uses K-means clustering method with RFM analysis to study customer's fluctuations over different time frames. We also apply the proposed electrocardiogram methodology for a real-world case study of food industry and the results are discussed in details
ABC-transporter blockage mediated by xanthotoxin and bergapten is the major pathway for chemosensitization of multidrug-resistant cancer cells.
Furanocoumarins derived from herbal and citrus extracts can act as antibacterial, antioxidant, immunomodulator, apoptotic, and selective anticancer agents, prompting a biological investigation to determine and predict their clinical therapeutic significance. Here, the cell cytotoxic effects of bergapten and xanthotoxin were analyzed alone and in combination with standard chemotherapeutics on three multidrug resistant cells and their nonresistant parental counterparts. The furanocoumarins modulatory effects on MDR1, BCRP, and MRP pump expression and function were investigated. Although quantitative real time PCR demonstrated that the MDR transcript level changes in a time dependent manner, flow cytometric analyses using fluorescent-labeled antibodies have indicated that bergapten and xanthotoxin had no significant effect on the protein levels. FACS analyses indicated that these prominent anticancer agents significantly blocked MDR1, BCRP, and MRP transporter function. Maximum furanocoumarin-mediated pump activity blockage in the MDR-resistant cells was quantified as 87% of normal and consequently, chemotherapeutic accumulation increased up to 2.7-fold and cytotoxicity tension increased 104-fold. MDR1 efflux kinetics also revealed that the maximum velocity and the pump affinity to daunorubicin were uncompetitively decreased. We conclude that bergapten and xanthotoxin are cytotoxic agents capable of preventing daunorubicin, mitoxantrone, and cisplatin binding to ABC-transporters and subsequently inhibiting their efflux out of cells and they may be a potential combination therapy for malignant cancers
A New Scheme to Direct Torque Control of Matrix Converter-Fed Five-Phase Permanent Magnet Synchronous Motor
Multiphase machines have gained an increasing attention due to their more advantages in comparison with three-phase machines. In recent literatures, only voltage source inverters (VSIs) have been used to supply five-phase drives. Matrix converters (MCs) pose many advantages over conventional VSIs, such as lack of dc-bulk capacitors, high quality power output waveform and higher number of output voltages. Due to some special applications of multiphase machines such as ship propulsion and aerospace, the volume of these drives is an important challenging problem. As a consequence, using MCs can be a reasonable alternative. In this paper, a new direct torque control (DTC) algorithm using a three-to-five phase MC is proposed for five-phase permanent magnet synchronous motors (PMSMs). All of output voltage space vectors of three-to-five phase MC are extracted and a new switching table is proposed. Because of higher number of output voltages in MCs, there is a degree of freedom to control input power factor to keep close to unit moreover the torque and flux control. In other words, this proposed method use the advantages of both DTC method and MCs. Simulation results show the effectiveness of presented method in different operation modes
Optimum Design of a Five-phase Permanent Magnet Synchronous Motor for Underwater Vehicles by use of Particle Swarm Optimization
Permanent magnet synchronous motors are efficient motors which have widespread applications in electric industry due to their noticeable features. One of the interesting applications of such motors is in underwater vehicles. In these cases, reaching to minimum volume and high torque of the motor are the major concern. Design optimization can enhance their merits considerably, thus reduce volume and improve performance of motors. In this paper, a new method for optimum design of a five-phase surface-mounted permanent magnet synchronous motor is presented to achieve minimum loss and magnet volume with an increased torque. A multi-objective optimization is performed in search for optimum dimensions of the motor and its permanent magnets using particle swarm optimization. The design optimization results in a motor with great improvement regarding the original motor. Finally, finite element analysis is utilized to validate the accuracy of the design
A comparison between the effect of systemic and coated drug delivery in osteoporotic bone after dental implantation
The increased life expectancy has boomed the demand of dental implants in the elderly. As a consequence, considering the effect of poorer bone quality, due to aging or associated diseases such as osteoporosis, on the success of dental restoration is becoming increasingly important. Bisphosphonates are one of the most used drugs to overcome the effect of osteoporosis as they increase bone density. Bisphosphonates modify the physiological bone remodeling process by adhering to the bone surface, reducing the activity of osteoclasts. This study aims at comparing the effect on bone remodeling of two drug delivery methods of Bisphosphonates: local delivery by coating the implant surface and systemic delivery. A chemo-mechano-biological bone remodeling model validated in a previous paper was used here. The two drug delivery schemes were modeled by means of a finite element approach. In the systemic drug delivery case, the amount of drug that reaches the bone compartment was calculated using a pharmacokinetic model while in the local drug delivery system, the dose was calculated using Fickean diffusion. In particular, the effect of Zoledronate is studied here. The two drug delivery approaches are compared between them and with a control case with no drug. The results show that the use of Bisphosphonates increases the mechanical strength of bone, thus improving the implant fixation along time. Systemic drug delivery affects the entire skeleton, while local drug delivery only affects the area around the dental implant, which reduces the side effects of Bisphosphonates, such as increasing the mineral content, which may promote bone brittleness and microdamage far from the implant. These results support the conclusion that dental implants coated with Bisphosphonates can be a good solution for osteoporotic or low bone density patients without the long-term side effects of systemic drug delivery. © 202
Micelle-Mediated Extraction and Cloud Point Pre-concentration for the Spectrophotometric Determination of Phenol in Water Samples
In this paper, a cloud point extraction method for the determination of trace amounts of phenol by spectrophotometry is described. The method is based on the colour reaction of phenol with diazotized p-nitroanilinean alkaline media and the cloud point extraction of azo dye product using of nonionic surfactant Triton X-114. The effects of reaction and extraction parameters were studied and optimum parameters were established. The calibration graph was linear in the range of 2.0–400 ng mL–1 of phenol. Detection limit based on three times the standard deviation of the blank (3Sb) was 1.0 ng mL–1 and the relative standard deviation (RSD) for 50 ng mL–1 of phenol was 1.73 % (n=10). The proposed method was applied for the determination of phenolin water samples.Keywords: Pre-concentration, cloud point extraction, phenol, spectrophotometry, water sample
Evaluation of Medical Metabolites in Boraginaceae Family
Boraginaceae family is known as a medicinal plant classified in dicotyledons. It isoriginated from Asia (Middle East). The aim of this study was to evaluate ingredient betweenspecies of Boraginaceae family based on physiological & phytochemical traits as well as seed fattyacid contents. species (E. russicum, E. italicum, E. amoenum, and B. officinalis) were evaluatedcarefully. All seeds were cultivated in identical conditions in a greenhouse in Tehran to assesseparameters such as tannins, phenols, anthocyanin, total protein, seed oil contents, SuperoxideDismutase (SOD), and Catalase (CAT) activity. Analysis of oil from seeds of EchiumL. determineddifferent fatty acids including Linolenic acid ( ), Linoleic acid ( ), Oleic acid ( )and Arachidonic acid ( ) as major fatty acids, while stearic acid ( ), Palmitic acid( ), Gama-Linolenic acid ( ) were the minor fatty acids extracted from seeds. Lowprotein content was observed in E. russicum( mg/g) and maximum level of protein was in B.officinalis( mg/g). E. amoenum had maximum phenols ( mg/g) whereas E. russicum hadminimum ( mg/g). For total phenol, B. officinalis had maxium phenols ( mg/g) whereas E.italicum had minimum ( mg/g). Anthocyanins: E. russicum had maximum anthocyanins (mg/g) whereas B. officinalis had minimum ( mg/g). In conclusion, it can be said that differentspecies had different amounts of secondary metabolites so that no regular relation would bedetected among plant species that we studied
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