| 1. |
- Ghanbarpour, A., et al.
(författare)
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Evaluation of heat sink performance using PCM and vapor chamber/heat pipe
- 2021
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Ingår i: Renewable energy. - : Elsevier Ltd. - 0960-1481 .- 1879-0682. ; 163, s. 698-719
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a numerical study on heat sink thermal performance using phase change materials (PCM) and a vapor chamber for heat source cooling. Heat sink performance in both natural and forced convection heat transfer modes is investigated. The influence of various geometrical parameters such as number, height and thickness of fins for three different modes of conventional heat sink, PCM-based heat sink and heat sink integrated with vapor chamber is studied. Numerical results showed that the number of fins and fin height were more effective than the fin thickness in reducing heat source temperature. Furthermore, in natural convection, the addition of PCM and vapor chamber to the heat sink reduces the heat source temperature by a maximum of 33.1% and 9.5%, respectively, compared to a conventional heat sink. But in forced convection, the use of vapor chamber reduces the heat source temperature by 7.9% while the addition of PCM to the heat sink affects its performance adversely. In fact when fresh air is blown to the heat sink, it provides a higher temperature potential at all the surfaces.
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| 2. |
- Hosseini, M., et al.
(författare)
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ISFET immunosensor improvement using amine-modified polystyrene nanobeads
- 2018
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Ingår i: Journal of Solid State Electrochemistry. - : Springer New York LLC. - 1432-8488 .- 1433-0768. ; 22:10, s. 3161-3169
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Tidskriftsartikel (refereegranskat)abstract
- Antigen-based sensing is recognized as a rapid and sensitive analysis among bioresearch groups. The potential of “on-site” analysis in such devices has been accompanied by some problems. Fabrication of silicon compatible and highly sensitive biosensors has been the center of excessive research within the past few years. In this paper, we report fabrication of two types of sensitive liquid oxide semiconductor (LOS) biosensors using nanostructures. These devices have been manufactured and characterized as immunosensors. These two types of sensors have been produced using different platforms for immobilization of proteins; one based on a functionalized silicon dioxide surface by 3-aminopropyltriethoxysilane (APTES) and another on the basis of using 50-nm amine-modified polystyrene nanobeads. The polystyrene platform not only benefits from its nanosize and high surface to volume ratio but also does not need any new protocol than what is already used for traditional immunosensing system. These sensors measure the change of threshold voltage of the semiconductor inversion inside the capacitor due to the bonding of antibodies to the linked peptides on the surface. Measurements showed that the sensitivity of 50-nm polystyrene-based sensor is much more than the oxide-based one. The nanobeads were then chosen to cover the gate of the ISFET for the amplified sensing. The ISFET devices were biased in a subthreshold region to demonstrate the maximum sensitivity to the accumulated charge on the gate. Repeatable results after different stress tests were obtained, which proves the suitability and reliability of the polystyrene nanobead platform for this application. Finally, a calibration curve has been derived that can be used for real sample measurements. The detection limit of 1.0152 μg/ml was calculated for the fabricated sensor. [Figure not available: see fulltext.].
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| 3. |
- Hosseini, S., et al.
(författare)
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Mapping the intellectual structure of GIS-T field (2008–2019) : a dynamic co-word analysis
- 2021
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Ingår i: Scientometrics. - : Springer Nature. - 0138-9130 .- 1588-2861. ; 126:4, s. 2667-2688
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Tidskriftsartikel (refereegranskat)abstract
- Using geographic information systems (GIS) widely for dealing with transportation problems (is well-known as GIS-T), has made it nessasary for researchers to discover the current state-of-the-art and predict the trends of future research. This paper aims to contribute to a better understanding of GIS-T research area from a longitudinal perspective, over the period 2008–2019. A co-word analysis was used to illustrate all the underlying subfields of GIS-T based on published papers in the Web of Science (WoS) database service. The main knowledge areas representing the intellectual structure of GIS-T including (a) sustainability, (b) health, (c) planning and management, and (d) methods and tools, were detected. Finally, in order to illustrate the structure and development of the identified clusters, two-dimensional maps and strategic diagrams for each period were drawn. This study is the first attempt to employ a text mining method so as to detect the conceptual structure of GIS-T research area from a complex and interdisciplinary literature.
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| 4. |
- Ougazzaden, A., et al.
(författare)
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Growth of GaN by metal organic vapor phase epitaxy on ZnO-buffered c-sapphire substrates
- 2008
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 310:5, s. 944-947
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Tidskriftsartikel (refereegranskat)abstract
- The materials quality and availability of large-area bulk GaN substrates is currently considered a key problem for the continuing development of improved GaN-based devices. Since industrial fabrication of bulk GaN substrates with suitable materials quality has proven very difficult, the opto-GaN industry is currently based on heteroepitaxy using either c-sapphire or 6H SiC substrates. ZnO is promising as a substrate material for GaN because it has the same wurtzite structure and a relatively small lattice mismatch (similar to 1.8%). In this study, we have successfully grown GaN by MOVPE on ZnO-buffered c-sapphire. The growth conditions required to both prevent ZnO degradation and grow monocrystal thin film of GaN have been obtained. SEM, HRXRD and micro-Raman characterizations underlined the presence of the two layers GaN and ZnO with high structural quality.
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| 5. |
- Yu, A. B., et al.
(författare)
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Characterization and optimization of dry releasing for the fabrication of RF MEMS capacitive switches
- 2007
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 17:10, s. 2024-2030
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses fabrication aspects of photoresist sacrificial layers for fabricating metal bridges of capacitive radio frequency (RF) microelectromechanical systems (MEMS) switches. First, reflow of the photoresist layer after lithography is investigated for reducing mechanical fracture of the metal layer by smoothing the edges of the sacrificial layer. Second, the dry-etch releasing process of the structures in an O-2 plasma has been investigated by identifying suitable etching parameters. The findings in this paper reveal that the mechanical performance of the released bridges strongly depends on the etch parameters. It is shown that especially the etching power affects the mean stress and the stress gradient in the bridge, which results in buckling and deformed bridge shape for an etching power above 500 W, drastically increasing the actuation voltage and reducing the down-state capacitance. Finally, the paper presents a suitable parameter set for the release etching of capacitive MEMS metal bridges.
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| 6. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 7. |
- Horvatovich, Peter, et al.
(författare)
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Quest for Missing Proteins : Update 2015 on Chromosome-Centric Human Proteome Project
- 2015
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Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 14:9, s. 3415-3431
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper summarizes the recent activities of the Chromosome-Centric Human Proteome Project (C-HPP) consortium, which develops new technologies to identify yet-to-be annotated proteins (termed "missing proteins") in biological samples that lack sufficient experimental evidence at the protein level for confident protein identification. The C-HPP also aims to identify new protein forms that may be caused by genetic variability, post-translational modifications, and alternative splicing. Proteogenomic data integration forms the basis of the C-HPP's activities; therefore, we have summarized some of the key approaches and their roles in the project. We present new analytical technologies that improve the chemical space and lower detection limits coupled to bioinformatics tools and some publicly available resources that can be used to improve data analysis or support the development of analytical assays. Most of this paper's content has been compiled from posters, slides, and discussions presented in the series of C-HPP workshops held during 2014. All data (posters, presentations) used are available at the C-HPP Wild (http://c-hpp.webhosting.rug.nl/) and in the Supporting Information.
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| 8. |
- Hosseini, A., et al.
(författare)
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Performance prediction of a hard-chine planing hull by employing different cfd models
- 2021
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Ingår i: Journal of Marine Science and Engineering. - : MDPI AG. - 2077-1312. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents CFD (Computational Fluid Dynamics) simulations of the performance of a planing hull in a calm-water condition, aiming to evaluate similarities and differences between results of different CFDmodels. The key differences between thesemodels are the ways they use to compute the turbulent flow and simulate themotion of the vessel. The planingmotion of a vessel on water leads to a strong turbulent fluid flowmotion, and themovement of the vessel fromits initial position can be relatively significant, which makes the simulation of the problem challenging. Two different frameworks including k-" and DES (Detached Eddy Simulation) methods are employed to model the turbulence behavior of the fluid motion of the air–water flow around the boat. Vertical motions of the rigid solid body in the fluid domain, which eventually converge to steady linear and angular displacements, are numerically modeled by using two approaches, including morphing and overset techniques. All simulations are performed with a similar mesh structure which allows us to evaluate the differences between results of the applied mesh motions in terms of computation of turbulent air–water flow around the vessel. Through quantitative comparisons, themorphing technique has been seen to result in smaller errors in the prediction of the running trim angle at high speeds. Numerical observations suggest that a DES model can modify the accuracy of the morphing mesh simulations in the prediction of the trim angle, especially at high-speeds. The DES model has been seen to increase the accuracy of the model in the computation of the resistance of the vessel in a high-speed operation, as well. This better level of accuracy in the prediction of resistance is a result of the calculation of the turbulent eddies emerging in the water flow in the downstream zone, which are not captured when a k-" framework is employed. The morphing approach itself can also increase the accuracy of the resistance prediction. The oversetmethod, however, overpredicts the resistance force. This overprediction is caused by the larger vorticity, computed in the direction of the waves, generated under the bow of the vessel. Furthermore, the overset technique is observed to result in larger hydrodynamic pressure on the stagnation line, which is linked to the greater trimangle, predicted by this approach. The DESmodel is seen to result in extra-damping of the second and third crests of transomwaves as it calculates the stronger eddies in the wake of the boat. Overall, a combination of themorphing and DESmodels is recommended to be used for CFDmodeling of a planing hull at high-speeds. This combined CFD model might be relatively slower in terms of computational time, but it provides a greater level of accuracy in the performance prediction, and can predict the energy damping, developed in the surrounding water. Finally, the results of the present paper demonstrate that a better level of accuracy in the performance prediction of the vessel might also be achieved when an oversetmeshmotion is used. This can be attained in future bymodifying themesh structure in such away that vorticity is not overpredicted and the generated eddies, emerging when a DESmodel is employed, are captured properly.
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| 9. |
- Mafi, Yousef, et al.
(författare)
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Ultra-Low-Power IoT Communications : A novel address decoding approach for wake-up receivers
- 2022
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Ingår i: IEEE Transactions on Green Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 2473-2400. ; 6:2, s. 1107-1121
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Tidskriftsartikel (refereegranskat)abstract
- Providing energy-efficient Internet of Things (IoT) connectivity has attracted significant attention in fifth-generation (5G) wireless networks and beyond. A potential solution for realizing a long-lasting network of IoT devices is to equip each IoT device with a wake-up receiver (WuR) to have always-accessible devices instead of always-on devices. WuRs typically comprise a radio frequency demodulator, sequence decoder, and digital address decoder and are provided with a unique authentication address in the network. Although the literature on efficient demodulators is mature, it lacks research on fast, low-power, and reliable address decoders. As this module continuously monitors the received ambient energy for potential paging of the device, its contribution to WuR’s power consumption is crucial. Motivated by this need, a low-power, reliable address decoder is developed in this paper. We further investigate the integration of WuR in low-power uplink/downlink communications and, using system-level energy analysis; we characterize operation regions in which WuR can contribute significantly to energy saving. The device-level energy analysis confirms the superior performance of our decoder. The results show that the proposed decoder significantly outperforms the state-of-the-art with power consumption of 60 nW, at cost of compromising negligible increase in decoding delay.
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| 10. |
- Pinto, Soraia, et al.
(författare)
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Nanoparticles targeting the intestinal Fc receptor enhance intestinal cellular trafficking of semaglutide
- 2024
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Ingår i: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 366, s. 621-636
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Tidskriftsartikel (refereegranskat)abstract
- Semaglutide is the first oral glucagon-like peptide-1 (GLP-1) analog commercially available for the treatment of type 2 diabetes. In this work, semaglutide was incorporated into poly(lactic-co-glycolic acid)-poly(ethylene glycol) (PLGA-PEG) nanoparticles (NPs) to improve its delivery across the intestinal barrier. The nanocarriers were surface-decorated with either a peptide or an affibody that target the human neonatal Fc receptor (hFcRn), located on the luminal cell surface of the enterocytes. Both ligands were successfully conjugated with the PLGA-PEG via maleimide-thiol chemistry and thereafter, the functionalized polymers were used to produce semaglutide-loaded NPs. Monodisperse NPs with an average size of 170 nm, neutral surface charge and 3% of semaglutide loading were obtained. Both FcRn-targeted NPs exhibited improved interaction and association with Caco-2 cells (cells that endogenously express the hFcRn), compared to non-targeted NPs. Additionally, the uptake of FcRn-targeted NPs was also observed to occur in human intestinal organoids (HIOs) expressing hFcRn through microinjection into the lumen of HIOs, resulting in potential increase of semaglutide permeability for both ligand-functionalized nanocarriers. Herein, our study demonstrates valuable data and insights that the FcRn-targeted NPs has the capacity to promote intestinal absorption of therapeutic peptides.
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