CMOS Closed-loop Control of MEMS Varactors

A closed-loop capacitance sensing and control mix-mode circuit with a dedicated sensor electrode and a proportional-integral controller was designed for MEMS varactors. The control was based on tuning the bias magnitude of the MEMS varactor according to

Flexible and optimal carbon dioxide capture system design for fossil-fueled power plants

Fossil fuel consumption remains a significant contributor to global greenhouse gas emissions, accounting for approximately 90% of the overall emissions, with fossil fuel power generation systems identified as a major source of CO2 emissions. Given the ongoing industrial activities and increasing energy demand, completely discontinuing the use of nonrenewable resources for power production is not feasible in the near future. CO2 capture and storage (CCS) technologies offer a promising option for continuing to utilize fossil fuels in a cleaner and more sustainable manner. The wide deployment of carbon capture technologies alone has the potential to decrease power plant emissions by as much as 90%. However, the current CCS technologies face several challenges for broad implementation, specifically significant energy requirements, high capital cost, and flexible operation. The current CCS technologies lead to a decrease in the net power output of the plant by approximately 25-40% and result in a substantial increase in power generation costs, potentially up to 70%. Another challenge is the requirement for flexible operation of CCS, as with the increasing penetration of renewable energy sources in the power grid, fossil fuel-fired power plants need to operate in a load-following manner to ease the integration of intermittent renewable sources. Consequently, significant fluctuations in the power plant flue gas necessitate flexible operation of the downstream carbon capture system to adapt to these changes. The above challenges necessitate implementing innovative solutions in the operation and design of carbon capture systems to reduce the energy penalty and cost of CO2 capturing and improve the flexible operation of CCS to accommodate both base-load and load-following operating of the power plants. Membrane systems offer promising advantages for separating CO2 from other components of power plant flue gas, although the process encounters several technical and economic challenges. These challenges must be addressed to optimize their design and integration with fossil-fueled power plants and enhance the feasibility of this environmentally-friendly technology for extensive adoption. This dissertation is focused on the development of flexible and efficient membrane-based carbon capture technologies for large-scale implementation and integration with both base-load and load-following fossil-fueled power plants under high renewable energy integration. This dissertation aims to address and provide insights into the current challenges by employing advanced modeling, simulation, and optimization techniques. An efficient and flexible multi-stage membrane-based CCS process is developed and optimized to address the challenge of energy requirements and cost penalties of the system. In this context, a comprehensive techno-economic model for the possible designs and operating strategies of the membrane separation process is developed in order to investigate the potential and viability of the membrane-based CCS system. Furthermore, the optimal process design and the possible trade-offs between performance indicators of the membrane-based CCS are presented with the aim of reducing energy and cost penalties. Finally, the transient behavior of the membrane-based process is further investigated at different disturbances and variations in the power plant operation imposed by the plant load-following behavior to address the required flexibility of the carbon capture system. The results substantiate that the proposed system could be an optimal and flexible option for the decarbonization of power plants operating in a load-following manner. The best possible trade-offs between objective functions show that the CO2 capture cost and energy penalty of the process could be as low as 13.1 $/tCO2 and 10Moreover, to address CCS integration challenges for the power plant operating at base-load mode, a hybrid solar-assisted membrane-amine CCS equipped with thermal energy storage is developed in order to improve the power plant operation and reduce the low-carbon electricity cost and the energy penalty associated with the CO2 capturing. In this regard, the conventional amine-based CCS is hybridized with a multi-stage membrane process for selective CO2 recirculation to improve the separation driving force and decrease both CCS equipment size and energy penalty. Furthermore, the solar energy field with 4-hour thermal energy storage is integrated with the developed CCS to provide the required thermal energy and flexibility for capturing 90$/MWh and 101.66 $/tonneCO2, among the other CCS-equipped power plant. The proposed designs and system investigation conducted in this dissertation and for addressing the technology challenges of the CO2 capture process hold considerable promise in facilitating the ideal reduction of carbon emissions from fossil-fueled power plants and promoting sustainability within the power sector. These advancements and developments, along with appropriate governmental policies and incentive programs, can potentially enhance the economic viability and desirability of CO2 capture systems, making them increasingly favorable for widespread implementation

Anti-angiogenesis effect of <em>crocous sativus </em>L. extract on matrix metalloproteinase gene activities in human breast carcinoma cells

Introduction: There is an interest in Crocous sativus L. (Saffron) mainly because of its biological properties. Biomedical research has focused on saffron as a powerful antioxidant, anti-inflammatory and anti-tumor, but its mechanism has not yet been thoroughly clarified. In this study, the effects of saffron aqua extract on matrix metalloproteinases (MMP) gene expression were investigated. Methods: In this experimental study, the saffron was extracted using water as solvent. MCF-7 cells in RPMI1640 medium were supplemented with 10 FBS and incubated at 37 ˚C with 5 CO2. After 24 h, the cells were treated by saffron extract at concentrations of 100, 200, 400 and 800 &mu;g/ml. 48 h after treatment, total RNA was extracted and cDNA was synthesized using specific primer. Synthesized products were analyzed by Real Time PCR to determine expression level of MMP. Results: Data analysis showed inhibitory effect of saffron at concentrations of 100 to 800 &mu;g/ml on MMP gene expression in comparison with control group. Reduction for 100, 200, 400 and 800 &mu;g/ml were 5, 18, 15, 11, respectively. According to data analysis treating MCF-7 cells with saffron at concentration of 200 &mu;g/ml caused the highest decrease, with 18 reduction in gene expression (P&lt;0.001). Conclusion: Results indicate decrease in the expression of MMP compared with controls revealing induction of inhibitory effects of saffron on angiogenesis which might be also considered as a promising chemotherapeutic agent in breast cancer treatment.</p

Synergistic effect of pulsed electromagnetic fields and saffron extract on osteogenic differentiation of bone marrow mesenchymal stem cells

Introduction: Pulsed electromagnetic fields (PEMFs) are usually used to treat non-union fractures. Saffron is a medicinal plant with various pharmacologic effects. In the present study, the synergistic effect of PEMF and saffron aqueous extract on osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) was evaluatedMethods: BMSCs were isolated from rat femur. After purification, the cells were divided into four groups including control group (did not receive any treatment), saffron alone (800 &mu;g/mL), PEMF alone (50 Hz, 3 times a weak, 2 hours for every time, for 2 weeks), and saffron plus PEMF. Cytotoxicity was measured using MTT assay. After calculating the IC50 value for saffron extract (1.5 mg/mL), a lower concentration (800 &mu;g/mL) was combined with PEMF. The differentiation of each cell group was evaluated using alkaline phosphatase (ALP) enzyme activity, alizarin red staining and reverse transcribed polymerase chain reaction (RT-PCR) method.Results: Saffron aqueous extract decreased dose-dependently the cell viability but the PEMF had not any significant effects on cell viability. The PEMF, saffron extract and their combination increased the ALP activity on day 10 but the increase was significant in synergist group. Alizarin red staining showed that mineralization groups were higher at day 14. RT-PCR results demonstrated that on the day 14 the group treated with both PEMF and saffron expressed osteogenic genes.Conclusion: Saffron extract combined with PEMFs could promote osteogenesis at the initial stage (the commitment of undifferentiated mesenchymal stem cells into osteoblast), hence, its usage might be beneficial in these patient

Computational study of quercetin effect on pre-apoptotic factors of Bad, Bak and Bim

Introduction: Quercetin is an effective compound which is found in many medicinal plants. Quercetin antioxidant properties against cancerous tumors and apoptosis induction have been demonstrated. This study is aimed to investigate the molecular dynamics of quercetin with regard to activating the pre-apoptotic factors such as Bim, Bak, and Bad using simulation software.Methods: In this study, the thermodynamic properties of flavonoid molecule of quercetin on three important factors in apoptotic pathway such as Bim, Bak, and Bad were investigated. After the three-dimensional structure of these molecules was obtained from NCBI and simulation was done by Gromacs software, docking stages were performed by AutoDock software and then the molecular dynamics of the complexes were investigated by Gromacs software.Results: The number of hydrogen bonds between quercetin and Bad was higher than Bak and Bim, which causes Bad to have lower energy than Bak and Bim. Mean root-mean-square deviation at 10 ns of simulation increased for Bad and Bak and decreased for Bim in quercetin presence. Root-mean-square fluctuation investigations indicated that Bim had the highest flexibility in quercetin presence compared to free state.Conclusion: Computational studies indicated that quercetin could have a greater effect on Bad compared to Bak and Bim. However it is necessary to investigate the effect mechanism of quercetin on these three pre-apoptotic factors in experimental studies

The effects of green tea extract on teratogenicity induced by low frequency electromagnetic field on bone marrow Balb/C mice embryo

Introduction: Electromagnetic fields produce free radicals which might be teratogen. Camellia sinensis is rich in natural antioxidants and antioxidants can neutralize free radicals effects. In present research the effect of C. sinensis extract in reduction of teratogenicity induced by electromagnetic field with 50 gauss intensity was studied on bone marrow of Balb/C mice fetuses. Methods: In this experimental study, 24 Balb/C pregnant mice were randomly divided into four groups: control, sham exposed (off position), experimental 1 (electromagnetic field with 50-gauss intensity) and experimental 2 (treatment by C. sinensis extract + electromagnetic field with 50-gauss intensity). After treatment period, the bone marrow aspirates of Balb/C mice embryos were prepared and studied by Giemsa. The quantitative data were analyzed by Kruskal-Wallis and Kolmogorov- Smirnov using SPSS16 software at the level of p&lt;0.05. Results: The mean number of promyelocytes, myelocytes, erythrocytes, necrotic and apoptotic cells in experimental group1 compared with sham exposed embryos showed significant increase but the mean number of eosinophils in experimental group 1 compared with sham exposed embryos showed significant decrease. The mean number of promyelocyte and erythrocyte in experimental group 2 compared with experimental group 1 showed significant decrease. The mean of necrotic and apoptotic cells, in experimental group 2 compared with experimental group 1 showed significant increase. Conclusion: Usage of C. sinensis can decrease the damage due to teratogenicity induced by low frequency electromagnetic field in some cells.</p

The synergic effect of glycyrrhizic acid and low frequency electromagnetic field on angiogenesis in chick chorioallantoic membrane

Objective: Much attention is paid to angiogenesis due to its mutual role in health and disease. Therefore, the effect of various chemical and physical agents on inhibition of this process has been recently studied. This study was conducted to investigate the synergic effect of glycyrrhizic acid and electromagnetic field on angiogenesis. Materials and Methods: In this experimental study, 44 Ross fertilized chicken eggs were randomly divided into four groups, one control and three experimental. Control group was kept with dimethyl sulfoxide on the eighth day, experimental group 1 treated with 200 gauss, 50 Hz electromagnetic field on the 10th day, experimental group 2 treated with 1 mg/ml glycyrrhizic acid on the eighth day, and experimental group 3 simultaneously treated with glycyrrhizic acid on the eighth day and electromagnetic field on the 10th day. On the 12th day, the images of chorioallantoic membrane samples were prepared using photostreomicroscope and the number and length of vessels were measured. Results: The mean number of vessels in the experimental groups 1 and 3 (29.31 +/- 3.60 and 27.43 +/- 4.61, respectively) was not significantly different from that in the control group (29.11 +/- 4.76) (p>0.05). The length of vessels in the experimental groups 1 and 3 (52.35 +/- 3.25 mm and 54.94 +/- 4.70 mm, respectively) decreased significantly (p<0.05) compared with the control group (61.79 +/- 6.46 mm). In experimental group 2, both length and number of vessels (54.53 +/- 5.85 mm and 23.96 +/- 3.94) decreased significantly compared with the control group (p<0.05). Conclusion: Electromagnetic field and glycyrrhizic acid separately led to inhibition of angiogenesis. However, use of electromagnetic field accompanied with glycyrrhizic acid not only did not increase but also decreased the inhibitory effect

Protective effect of date palm pollen (<em>Phoenix dactylifera)</em> on sperm parameters and sexual hormones in male NMRI mice exposed to low frequency electromagnetic field (50 Hz)

Introduction: Exposure to electromagnetic fields (EMFs) induces harmful effects on testis and reproductive activities. In traditional medicine, date palm pollen (DPP) which has remarkable nutritional values is used for curing male infertility and impotency. The aim of this study was to investigate the protective effect of DPP in preventing the detrimental effects of low frequency electromagnetic field (50 Hz) on sperm parameters and sexual hormones. Methods: Adult male mice were randomly divided into 7 groups of 8 and exposed to EMF 4 h/day for 10 days. In this study experimental groups received DPP with doses of 25, 50, 100 and 200 mg/kg, respectively before exposure. At the end of the experiment each group were tested for sperm parameters including: motility, count, morphology, viability and the level of luteinizing hormone (LH) and testosterone. Results: Our results revealed that exposure to EMF induced significant reduction (P &lt; .001) in sperm count, viability and progressive motility in comparison with control group. EMF caused abnormalities in sperm and significant decrease in testosterone level while there was no significant difference in level. Administration of DPP before exposure improved the sperm count, viability, motility and testosterone level in experimental groups. In addition, pretreatment with DPP prevented the sperm abnormality induced by EMF. Conclusion: The results indicate the protective effect of DPP against EMF adverse effects on sperm parameters and sexual hormones in male mice.</p

Anti-angiogenesis effect of crocous sativus L. extract on matrix metalloproteinase gene activities in human breast carcinoma cells

Introduction: There is an interest in Crocous sativus L. (Saffron) mainly because of its biological properties. Biomedical research has focused on saffron as a powerful antioxidant, anti-inflammatory and anti-tumor, but its mechanism has not yet been thoroughly clarified. In this study, the effects of saffron aqua extract on matrix metalloproteinases (MMP) gene expression were investigated. Methods: In this experimental study, the saffron was extracted using water as solvent. MCF-7 cells in RPMI1640 medium were supplemented with 10% FBS and incubated at 37 ˚C with 5% CO2. After 24 h, the cells were treated by saffron extract at concentrations of 100, 200, 400 and 800 μg/ml. 48 h after treatment, total RNA was extracted and cDNA was synthesized using specific primer. Synthesized products were analyzed by Real Time PCR to determine expression level of MMP. Results: Data analysis showed inhibitory effect of saffron at concentrations of 100 to 800 μg/ml on MMP gene expression in comparison with control group. Reduction for 100, 200, 400 and 800 μg/ml were 5%, 18%, 15%, 11%, respectively. According to data analysis treating MCF-7 cells with saffron at concentration of 200 μg/ml caused the highest decrease, with 18% reduction in gene expression (P<0.001). Conclusion: Results indicate decrease in the expression of MMP compared with controls revealing induction of inhibitory effects of saffron on angiogenesis which might be also considered as a promising chemotherapeutic agent in breast cancer treatment