1,206 research outputs found

    Miniaturized Microstrip Filter Design Using Active Learning Method

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    Relating coupling and external quality factor of a filter to the physical parameters of the structure which is the final step of any filter design is usually complicated due to geometrical complexities of the filter, or in the case of microstrip resonators due to the lack of the exact solution for the field distribution. Therefore, common approach is using time consuming full wave simulations. In this paper active learning method (ALM) which is a fuzzy-based modeling technique developed by a procedure algorithmically mimics the information-handling process of the human brain, is proposed to overcome this drawback. Modeling steps of an unknown function using ALM will be described using an illustrative example. Afterwards, the modeling approach will be implemented to model coupling factor between two coupled spiral resonators (SRs) for two different coupling structures and external quality factor of the same resonator. Accuracy of the extracted surfaces is validated using two different criteria. Using the extracted surfaces; a four pole chebychev bandpass filter was designed and fabricated. Good agreement between the measured response and simulation validated the accuracy of the extracted surfaces again. Comparing the fabricated SR filter with a square open loop resonator (SOLR) one demonstrates more than 70% of filter area reduction

    Disulfide-induced self-assembled targets: A novel strategy for the label free colorimetric detection of DNAs/RNAs via unmodified gold nanoparticles

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    A modified non-cross-linking gold-nanoparticles (Au-NPs) aggregation strategy has been developed for the label free colorimetric detection of DNAs/RNAs based on self-assembling target species in the presence of thiolated probes. Two complementary thiol- modified probes, each of which specifically binds at one half of the target introduced SH groups at both ends of dsDNA. Continuous disulfide bond formation at 3′ and 5′ terminals of targets leads to the self-assembly of dsDNAs into the sulfur- rich and flexible products with different lengths. These products have a high affinity for the surface of Au-NPs and efficiently protect the surface from salt induced aggregation. To evaluate the assay efficacy, a small part of the citrus tristeza virus (CTV) genome was targeted, leading to a detection limit of about 5 × 10-9 mol.L-1 over a linear ranged from 20 × 10-9 to 10 × 10-7 mol.L-1. This approach also exhibits good reproducibility and recovery levels in the presence of plant total RNA or human plasma total circulating RNA extracts. Self-assembled targets can be then sensitively distinguished from non-assembled or mismatched targets after gel electrophoresis. The disulfide reaction method and integrating self-assembled DNAs/RNAs targets with bare AuNPs as a sensitive indicator provide us a powerful and simple visual detection tool for a wide range of applications

    Thermoluminescence behavior of KClXBr1−X: in mixed crystals exposed to gamma radiation

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    In-doped KClXBr1−X (X=1, 0.75, 0.5, 0.25 and 0) mixed crystal has been grown by the Czochralski method. The segregation coefficient of In was studied by the inductively coupled plasma atomic emission spectrometry (ICP-OES). The crystal structure has been determined using X-ray diffraction (XRD) analysis. The thermoluminescence (TL) characterization of KClXBr1−X mixed crystals, exposed to gamma radiation has been performed. The results show the introduction of the dopants ions induced changes in the TL glow curve structure. The TL results suggest that doped KClXBr1−X mixed crystal has good potential active dosimeter applications for gamma ray irradiation

    Finite quantum tomography via semidefinite programming

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    Using the the convex semidefinite programming method and superoperator formalism we obtain the finite quantum tomography of some mixed quantum states such as: qudit tomography, N-qubit tomography, phase tomography and coherent spin state tomography, where that obtained results are in agreement with those of References \cite{schack,Pegg,Barnett,Buzek,Weigert}.Comment: 25 page

    Curcumin: A new candidate for melanoma therapy?

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    Melanoma remains among the most lethal cancers and, in spite of great attempts that have been made to increase the life span of patients with metastatic disease, durable and complete remissions are rare. Plants and plant extracts have long been used to treat a variety of human conditions; however, in many cases, effective doses of herbal remedies are associated with serious adverse effects. Curcumin is a natural polyphenol that shows a variety of pharmacological activities including anti-cancer effects, and only minimal adverse effects have been reported for this phytochemical. The anti-cancer effects of curcumin are the result of its anti-angiogenic, pro-apoptotic and immunomodulatory properties. At the molecular and cellular level, curcumin can blunt epithelial-to-mesenchymal transition and affect many targets that are involved in melanoma initiation and progression (e.g., BCl2, MAPKS, p21 and some microRNAs). However, curcumin has a low oral bioavailability that may limit its maximal benefits. The emergence of tailored formulations of curcumin and new delivery systems such as nanoparticles, liposomes, micelles and phospholipid complexes has led to the enhancement of curcumin bioavailability. Although in vitro and in vivo studies have demonstrated that curcumin and its analogues can be used as novel therapeutic agents in melanoma, curcumin has not yet been tested against melanoma in clinical practice. In this review, we summarized reported anti-melanoma effects of curcumin as well as studies on new curcumin formulations and delivery systems that show increased bioavailability. Such tailored delivery systems could pave the way for enhancement of the anti-melanoma effects of curcumin. © 2016 UIC

    N-acetylcysteine in a Double-Blind Randomized Placebo-Controlled Trial: Toward Biomarker-Guided Treatment in Early Psychosis.

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    Biomarker-guided treatments are needed in psychiatry, and previous data suggest oxidative stress may be a target in schizophrenia. A previous add-on trial with the antioxidant N-acetylcysteine (NAC) led to negative symptom reductions in chronic patients. We aim to study NAC's impact on symptoms and neurocognition in early psychosis (EP) and to explore whether glutathione (GSH)/redox markers could represent valid biomarkers to guide treatment. In a double-blind, randomized, placebo-controlled trial in 63 EP patients, we assessed the effect of NAC supplementation (2700 mg/day, 6 months) on PANSS, neurocognition, and redox markers (brain GSH [GSHmPFC], blood cells GSH levels [GSHBC], GSH peroxidase activity [GPxBC]). No changes in negative or positive symptoms or functional outcome were observed with NAC, but significant improvements were found in favor of NAC on neurocognition (processing speed). NAC also led to increases of GSHmPFC by 23% (P = .005) and GSHBC by 19% (P = .05). In patients with high-baseline GPxBC compared to low-baseline GPxBC, subgroup explorations revealed a link between changes of positive symptoms and changes of redox status with NAC. In conclusion, NAC supplementation in a limited sample of EP patients did not improve negative symptoms, which were at modest baseline levels. However, NAC led to some neurocognitive improvements and an increase in brain GSH levels, indicating good target engagement. Blood GPx activity, a redox peripheral index associated with brain GSH levels, could help identify a subgroup of patients who improve their positive symptoms with NAC. Thus, future trials with antioxidants in EP should consider biomarker-guided treatment

    Compactifications of topological spaces via commutative algebra

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    In this paper, using commutative algebra, then new and significant advances on the compactifications of topological spaces, especially on the Stone-\v{C}ech and Alexandroff compactifications have been made. Especially among them, it is proved that the minimal spectrum of the direct product of a family of integral domains and also the maximal spectrum of the direct product of a family of local rings both indexed by a set XX are the Stone-\v{C}ech compactifications of the discrete space XX. Some applications of this study are given. Especially, it is shown that the Stone-\v{C}ech compactification of an arbitrary topological space XX is obtained from the Stone-\v{C}ech compactification of the discrete space XX by passing to a its certain quotient. A natural and simple way to construct ultra-rings is introduced, then this new approach is used to obtain nontrivial results on the Stone-\v{C}ech compactification.Comment: 19 page

    Production performance of hydraulic fractures in tight gas sands, a numerical simulation approach. Journal of Petroleum Science and Engineering

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    Hydraulically fractured tight gas reservoirs are one of the most common unconventional gas sources being produced today, and will be a regular source of gas in the future. The extremely low permeability of tight gas sands leads to inaccuracy of conventional build-up and draw-down well test results. This is primarily due to the increased time required for transient flow in tight gas sands to reach pseudo-steady state condition. To increase accuracy, well tests for tight gas reservoirs must be run for longer periods of time which is in most cases not economically viable. The large amount of downtime required to conduct well tests in tight sands makes them far less economical than conventional reservoirs, which leads to the need for accurate simulation of tight gas reservoir well tests. This paper presents simulation results of a 3-D hydraulically fractured tight gas model created using Eclipse software. The key aims are to analyze the effect of differing fracture orientation, number and length. The focus of the simulation runs will be on the effect of hydraulic fracture orientation and length. The results will be compared to simulation runs without the abovementioned factors to determine their effects on production rates and well performance analysis. All results are plotted alongside an un-fractured tight gas scenario in order to put the hydraulic fracture performance in perspective. Key findings from this work include an approximately linear relationship between initial gas rate and the number of hydraulic fractures intersecting the wellbore. In addition, fracture length is found to have less of an impact on initial gas rate compared to number of fractures intersecting the wellbore, for comparable total fracture volumes

    Characterizing natural fractures productivity in tight gas Reservoirs

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    Tight formations normally have production problems mainly due to very low matrix permeability and various forms of formation damage that occur during drilling completion and production operation. In naturally fractured tight gas reservoirs, gas is mainly stored in the rock matrix with very low permeability, and the natural fractures have the main contribution on total gas production. Therefore, identifying natural fractures characteristics in the tight formations is essential for well productivity evaluations. Well testing and logging are the common tools employed to evaluate well productivity. Use of image log can provide fracture static parameters, and welltest analysis can provide data related to reservoir dynamic parameters. However, due to the low matrix permeability and complexity of the formation in naturally fractured tight gas reservoirs, welltest data are affected by long wellbore storage effect that masks the reservoir response to pressure change, and it may fail to provide dual-porosity dual-permeability models dynamic characteristics such as fracture permeability, fracture storativity ratio and interporosity flow coefficient.Therefore, application of welltest and image log data in naturally fractured tight gas reservoirs for meaningful results may not be well understood and the data may be difficult to interpret. This paper presents the estimation of fracture permeability in naturally fractured tight gas formations, by integration of welltest analysis results and image log data based on Kazemi’s simplified model. Reservoir simulation of dual-porosity and dual-permeability systems and sensitivity analysis are performed for different matrix and fracture parameters to understand the relationship between natural fractures parameters with welltest permeability. The simulation results confirmed reliability of the proposed correlation for fracture permeability estimation. A field example is also shown to demonstrate application of welltest analysis and image log data processing results in estimating average permeability of natural fractures for the tight gas reservoir
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