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Micromachines, Volume 9, Issue 1 (January 2018)

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Cover Story (view full-size image) Bioelectronic medicine has been hailed as a new type of medicine to treat/manage chronic diseases. [...] Read more.
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Open AccessArticle Investigation on the Quality Factor Limit of the (111) Silicon Based Disk Resonator
Micromachines 2018, 9(1), 25; https://doi.org/10.3390/mi9010025
Received: 29 November 2017 / Revised: 4 January 2018 / Accepted: 8 January 2018 / Published: 22 January 2018
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Abstract
Quality factor is one of the most important parameters for a MEMS resonator. Most MEMS resonators are dominated by thermoelastic dissipation (TED). This paper demonstrates that the TED in a disk resonator that is made of (111) single-crystal silicon is surpassed by clamping
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Quality factor is one of the most important parameters for a MEMS resonator. Most MEMS resonators are dominated by thermoelastic dissipation (TED). This paper demonstrates that the TED in a disk resonator that is made of (111) single-crystal silicon is surpassed by clamping loss. The stiffness-mass decoupling design method, combined with reducing the beam width, was used to engineer high QTED. Experiments show that Q of the (111) disk resonator have an upper boundary that is determined by the clamping loss caused by the unbalanced out-of-plane displacement. The origin of the out-of-plane displacement is explained by theory and simulation. Full article
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Open AccessArticle In Vivo Experimental Study of Noninvasive Insulin Microinjection through Hollow Si Microneedle Array
Micromachines 2018, 9(1), 40; https://doi.org/10.3390/mi9010040
Received: 25 October 2017 / Revised: 2 January 2018 / Accepted: 16 January 2018 / Published: 20 January 2018
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Abstract
An experimental study of in vivo insulin delivery through microinjection by using hollow silicon microneedle array is presented. A case study was carried out on a healthy human subject in vivo to determine the influence of delivery parameters on drug transfer efficiency. As
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An experimental study of in vivo insulin delivery through microinjection by using hollow silicon microneedle array is presented. A case study was carried out on a healthy human subject in vivo to determine the influence of delivery parameters on drug transfer efficiency. As a microinjection device, a hollow microneedle array (13 × 13 mm2) having 100 microneedles (220 µm high, 130 µm-outer diameter and 50 µm-inner diameter) was designed and fabricated using classical microfabrication techniques. The efficiency of the delivery process was first characterized using methylene blue and a saline solution. Based on these results, the transfer efficiency was found to be predominantly limited by the inability of viable epidermis to absorb and allow higher drug transport toward the capillary-rich region. Two types of fast-acting insulin were used to provide evidence of efficient delivery by hollow MNA to a human subject. By performing blood analyses, infusion of more-concentrated insulin (200 IU/mL, international units (IU)) exhibited similar blood glucose level drop (5–7%) compared to insulin of standard concentration (100 IU/mL), however, significant increase of serum insulin (40–50%) with respect to the preinfusion values was determined. This was additionally confirmed by a distinctive increase of insulin to C-peptide ratio as compared to preinfusion ratio. Moreover, we noticed that this route of administration mimics a multiple dose regimen, able to get a “steady state” for insulin plasma concentration. Full article
(This article belongs to the Special Issue Silicon-based Micro/Nanofabrication for Biomedical Applications)
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Open AccessFeature PaperArticle A Platform for Mechano(-Electrical) Characterization of Free-Standing Micron-Sized Structures and Interconnects
Micromachines 2018, 9(1), 39; https://doi.org/10.3390/mi9010039
Received: 11 December 2017 / Revised: 10 January 2018 / Accepted: 12 January 2018 / Published: 18 January 2018
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Abstract
A device for studying the mechanical and electrical behavior of free-standing micro-fabricated metal structures, subjected to a very large deformation, is presented in this paper. The free-standing structures are intended to serve as interconnects in high-density, highly stretchable electronic circuits. For an easy,
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A device for studying the mechanical and electrical behavior of free-standing micro-fabricated metal structures, subjected to a very large deformation, is presented in this paper. The free-standing structures are intended to serve as interconnects in high-density, highly stretchable electronic circuits. For an easy, damage-free handling and mounting of these free-standing structures, the device is designed to be fabricated as a single chip/unit that is separated into two independently movable parts after it is fixed in the tensile test stage. Furthermore, the fabrication method allows for test structures of different geometries to be easily fabricated on the same substrate. The utility of the device has been demonstrated by stretching the free-standing interconnect structures in excess of 1000% while simultaneously measuring their electrical resistance. Important design considerations and encountered processing challenges and their solutions are discussed in this paper. Full article
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Open AccessEditorial Editorial for the Special Issue on Ultrafast Laser Fabrication for Lab-on-a-Chip
Micromachines 2018, 9(1), 38; https://doi.org/10.3390/mi9010038
Received: 15 January 2018 / Accepted: 16 January 2018 / Published: 18 January 2018
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Abstract
Ultrafast laser microfabrication is a very powerful method for producing integrated devices in transparent materials [1].[...] Full article
(This article belongs to the Special Issue Ultrafast Laser Fabrication for Lab-on-a-Chip)
Open AccessArticle Chemical Mechanical Planarization and Old Italian Violins
Micromachines 2018, 9(1), 37; https://doi.org/10.3390/mi9010037
Received: 21 December 2017 / Revised: 12 January 2018 / Accepted: 15 January 2018 / Published: 18 January 2018
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Abstract
Previous studies have shown that spectral analysis based on force data can elucidate fundamental physical phenomena during chemical mechanical planarization (CMP). While it has not been literally described elsewhere, such analysis was partly motivated by modern violinmakers and physicists studying Old Italian violins,
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Previous studies have shown that spectral analysis based on force data can elucidate fundamental physical phenomena during chemical mechanical planarization (CMP). While it has not been literally described elsewhere, such analysis was partly motivated by modern violinmakers and physicists studying Old Italian violins, who were trying to discover spectral relations to sound quality. In this paper, we draw parallels between violins and CMP as far as functionality and spectral characteristics are concerned. Inspired by the de facto standard of violin testing via hammer strikes on the base edge of a violin’s bridge, we introduce for the first time, a mobility plot for the polisher by striking the wafer carrier head of a CMP polisher with a hammer. Results show three independent peaks that can indeed be attributed to the polisher’s natural resonance. Extending our study to an actual CMP process, similar to hammered and bowed violin tests, at lower frequencies the hammered and polished mobility peaks are somewhat aligned. At higher frequencies, peak alignment becomes less obvious and the peaks become more isolated and defined in the case of the polished wafer spectrum. Lastly, we introduce another parameter from violin testing known as directivity, Δ, which in our case, we define as the ratio of shear force variance to normal force variance acquired during CMP. Results shows that under identical polishing conditions, Δ increases with the polishing removal rate. Full article
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Open AccessFeature PaperArticle Hydrogel Fiber Cultivation Method for Forming Bacterial Cellulose Microspheres
Micromachines 2018, 9(1), 36; https://doi.org/10.3390/mi9010036
Received: 8 December 2017 / Revised: 28 December 2017 / Accepted: 15 January 2018 / Published: 17 January 2018
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Abstract
Forming microspheres or microbeads from nanofibrous materials has recently attracted research interest for their applications in various fields, because these structures greatly impact cellular behaviors and functions. However, conventional methods of preparing microspheres or microbeads have limitations, such as limited variety of material.
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Forming microspheres or microbeads from nanofibrous materials has recently attracted research interest for their applications in various fields, because these structures greatly impact cellular behaviors and functions. However, conventional methods of preparing microspheres or microbeads have limitations, such as limited variety of material. Here, we propose a new fabrication process for forming a nanofibrous microsphere composed of bacterial cellulose (BC), which is synthesized through fermentation by specific bacteria. The process uses a hydrogel fiber containing spherical cavities. The bacteria encapsulated into the cavities produce BC, resulting in the formation of BC microspheres. Because of its simplicity, robustness, and cost-effectiveness, this process is promising for applications, such as in biochemical engineering and cell delivery systems. Full article
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Open AccessArticle Pair Interaction of Catalytical Sphere Dimers in Chemically Active Media
Micromachines 2018, 9(1), 35; https://doi.org/10.3390/mi9010035
Received: 30 December 2017 / Revised: 11 January 2018 / Accepted: 11 January 2018 / Published: 17 January 2018
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Abstract
We study the pair dynamics of two self-propelled sphere dimers in the chemically active medium in which a cubic autocatalytic chemical reaction takes place. Concentration gradient around the dimer, created by reactions occurring on the catalytic sphere surface and responsible for the self-propulsion,
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We study the pair dynamics of two self-propelled sphere dimers in the chemically active medium in which a cubic autocatalytic chemical reaction takes place. Concentration gradient around the dimer, created by reactions occurring on the catalytic sphere surface and responsible for the self-propulsion, is greatly influenced by the chemical activities of the environment. Consequently, the pair dynamics of two dimers mediated by the concentration field are affected. In the particle-based mesoscopic simulation, we combine molecular dynamics (MD) for potential interactions and reactive multiparticle collision dynamics (RMPC) for solvent flow and bulk reactions. Our results indicate three different configurations between a pair of dimers after the collision, i.e., two possible scenarios of bound dimer pairs and one unbound dimer pair. A phase diagram is sketched as a function of the rate coefficients of the environment reactions. Since the pair interactions are the basic elements of larger scale systems, we believe the results may shed light on the understanding of the collective dynamics. Full article
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Open AccessArticle Static and Dynamic Mechanical Behaviors of Electrostatic MEMS Resonator with Surface Processing Error
Micromachines 2018, 9(1), 34; https://doi.org/10.3390/mi9010034
Received: 30 November 2017 / Revised: 31 December 2017 / Accepted: 12 January 2018 / Published: 17 January 2018
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Abstract
The micro-electro-mechanical system (MEMS) resonator developed based on surface processing technology usually changes the section shape either due to excessive etching or insufficient etching. In this paper, a section parameter is proposed to describe the microbeam changes in the upper and lower sections.
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The micro-electro-mechanical system (MEMS) resonator developed based on surface processing technology usually changes the section shape either due to excessive etching or insufficient etching. In this paper, a section parameter is proposed to describe the microbeam changes in the upper and lower sections. The effect of section change on the mechanical properties is studied analytically and verified through numerical and finite element solutions. A doubly-clamped microbeam-based resonator, which is actuated by an electrode on one side, is investigated. The higher-order model is derived without neglecting the effects of neutral plane stretching and electrostatic nonlinearity. Further, the Galerkin method and Newton–Cotes method are used to reduce the complexity and order of the derived model. First of all, the influence of microbeam shape and gap variation on the static pull-in are studied. Then, the dynamic analysis of the system is investigated. The method of multiple scales (MMS) is applied to determine the response of the system for small amplitude vibrations. The relationship between the microbeam shape and the frequency response is discussed. Results show that the change of section and gap distance can make the vibration soften, harden, and so on. Furthermore, when the amplitude of vibration is large, the frequency response softening effect is weakened by the MMS. If the nonlinearity shows hardening-type behavior at the beginning, with the increase of the amplitude, the frequency response will shift from hardening to softening behavior. The large amplitude in-well motions are studied to investigate the transitions between hardening and softening behaviors. Finally, the finite element analysis using COMSOL software (COMSOL Inc., Stockholm, Sweden) is carried out to verify the theoretical results, and the two results are very close to each other in the stable region. Full article
(This article belongs to the Special Issue Micro-Resonators: The Quest for Superior Performance)
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Open AccessEditorial Acknowledgement to Reviewers of Micromachines in 2017
Micromachines 2018, 9(1), 33; https://doi.org/10.3390/mi9010033
Received: 17 January 2018 / Accepted: 17 January 2018 / Published: 17 January 2018
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Abstract
Peer review is an essential part in the publication process, ensuring that Micromachines maintains high quality standards for its published papers.[...] Full article
Open AccessReview Detecting Chemical Hazards in Foods Using Microfluidic Paper-Based Analytical Devices (μPADs): The Real-World Application
Micromachines 2018, 9(1), 32; https://doi.org/10.3390/mi9010032
Received: 2 January 2018 / Revised: 15 January 2018 / Accepted: 16 January 2018 / Published: 17 January 2018
Cited by 2 | PDF Full-text (864 KB) | HTML Full-text | XML Full-text
Abstract
Food safety remains one of the most important issues in most countries and the detection of food hazards plays a key role in the systematic approach to ensuring food safety. Rapid, easy-to-use and low-cost analytical tools are required to detect chemical hazards in
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Food safety remains one of the most important issues in most countries and the detection of food hazards plays a key role in the systematic approach to ensuring food safety. Rapid, easy-to-use and low-cost analytical tools are required to detect chemical hazards in foods. As a promising candidate, microfluidic paper-based analytical devices (μPADs) have been rarely applied to real food samples for testing chemical hazards, although numerous papers have been published in this field in the last decade. This review discusses the current status and concerns of the μPAD applications in the detection of chemical hazards in foods from the perspective of food scientists, mainly for an audience with a background in mechanical and chemical engineering who may have interests in exploring the potential of μPAD to address real-world food safety issues. Full article
(This article belongs to the Special Issue Microfluidic Sensors)
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Open AccessArticle Design Considerations for a Sub-mW Wireless Medical Body-Area Network Receiver Front End
Micromachines 2018, 9(1), 31; https://doi.org/10.3390/mi9010031
Received: 31 October 2017 / Revised: 6 January 2018 / Accepted: 12 January 2018 / Published: 17 January 2018
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Abstract
Wireless medical body-area networks are used to connect sensor nodes that monitor vital parameters. The radio consumes a large portion of the sensor energy budget, and hence its power dissipation should be minimized. The low-noise amplifier (LNA) is an important component of the
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Wireless medical body-area networks are used to connect sensor nodes that monitor vital parameters. The radio consumes a large portion of the sensor energy budget, and hence its power dissipation should be minimized. The low-noise amplifier (LNA) is an important component of the receiver, and must guarantee low-noise amplification and impedance matching. In this work, an ultra-low-voltage ultra-low-power LNA is proposed that, thanks to the proposed transformer-based gate boosting technique, has a reduced current consumption of only 160 μA and can operate with a supply as low as 0.18 V. The LNA was designed using 40 nm Complementary Metal-Oxide Semiconductor (CMOS) technology and features a voltage gain of 14 dB, 5.2 dB NF and −8.6 dBm IIP3. This performance is comparable to a prior work by the same authors, but with the minimum supply voltage reduced by a factor of 4x. Full article
(This article belongs to the Special Issue Wireless Microdevices and Systems for Biomedical Applications)
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Open AccessArticle 3D Multi-Microchannel Helical Mixer Fabricated by Femtosecond Laser inside Fused Silica
Micromachines 2018, 9(1), 29; https://doi.org/10.3390/mi9010029
Received: 22 November 2017 / Revised: 8 January 2018 / Accepted: 12 January 2018 / Published: 16 January 2018
Cited by 4 | PDF Full-text (2063 KB) | HTML Full-text | XML Full-text
Abstract
Three-dimensional (3D) multi-microchannel mixers can meet the requirements of different combinations according to actual needs. Rapid and simple creation of 3D multi-microchannel mixers in a “lab-on-a-chip” platform is a significant challenge in micromachining. In order to realize the complex mixing functions of microfluidic
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Three-dimensional (3D) multi-microchannel mixers can meet the requirements of different combinations according to actual needs. Rapid and simple creation of 3D multi-microchannel mixers in a “lab-on-a-chip” platform is a significant challenge in micromachining. In order to realize the complex mixing functions of microfluidic chips, we fabricated two kinds of complex structure micromixers for multiple substance mixes simultaneously, separately, and in proper order. The 3D multi-microchannel mixers are fabricated by femtosecond laser wet etch technology inside fused silica. The 3D multi-microchannel helical mixers have desirable uniformity and consistency, which will greatly expand their utility and scope of application. Full article
(This article belongs to the Special Issue Passive Micromixers) Printed Edition available
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Open AccessArticle The Development of a Triaxial Cutting Force Sensor Based on a MEMS Strain Gauge
Micromachines 2018, 9(1), 30; https://doi.org/10.3390/mi9010030
Received: 17 November 2017 / Revised: 10 January 2018 / Accepted: 11 January 2018 / Published: 15 January 2018
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Abstract
Cutting force measurement is a quintessential task for status monitoring during machining. In the past, a number of cutting force sensors have been developed, each featuring a different set of performance advantages. In a pursuit to improve the measuring sensitivity and reduce the
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Cutting force measurement is a quintessential task for status monitoring during machining. In the past, a number of cutting force sensors have been developed, each featuring a different set of performance advantages. In a pursuit to improve the measuring sensitivity and reduce the cross-interference error, in this paper we propose a triaxial cutting force sensor based on a commercial micro-electro-mechanical system (MEMS) strain gauge. An elastic-sensitive element comprised of two mutual-perpendicular octagonal rings is designed for triaxial cutting force measurement, and a decoupling matrix is derived from static calibration to reduce cross-interference. It can be concluded from static calibration that the sensor’s sensitivity is 0.32 mV/N, 0.32 mV/N, and 0.05 mV/N in triaxial directions, and the proposed decoupling matrix is able to reduce cross-interference error to 0.14%, 0.25%, and 4.42%. Dynamic cutting force measurement shows that the cutting force sensor can reflect the variation of cutting status very well, it is qualified to measure triaxial cutting forces in practical applications. Full article
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Open AccessArticle Fabrication of a Lab-on-Chip Device Using Material Extrusion (3D Printing) and Demonstration via Malaria-Ab ELISA
Micromachines 2018, 9(1), 27; https://doi.org/10.3390/mi9010027
Received: 13 December 2017 / Revised: 7 January 2018 / Accepted: 11 January 2018 / Published: 14 January 2018
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Abstract
Additive manufacturing, such as fused deposition modeling (FDM), has been increasingly employed to produce microfluidic platforms due to ease of use, wide distribution of affordable 3D printers and relatively inexpensive materials for printing. In this work, we discuss fabrication and testing of an
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Additive manufacturing, such as fused deposition modeling (FDM), has been increasingly employed to produce microfluidic platforms due to ease of use, wide distribution of affordable 3D printers and relatively inexpensive materials for printing. In this work, we discuss fabrication and testing of an FDM-printed fully automated colorimetric enzyme-linked immunosorbent assay (ELISA) designed to detect malaria. The detection platform consists of a disposable 3D-printed fluidic cartridge (with elastomeric silicone domes on top of reagent-storage reservoirs) and a nondisposable frame with servomotors and electronic controls such as an Arduino board and a rechargeable battery. The system is controlled by a novel interface where a music file (so-called “song”) is sent to the Arduino board, where the onboard program converts the set of frequencies into action of individual servomotors to rotate their arms a certain amount, thus depressing specific elastomeric domes atop reagent reservoirs and displacing the specific reagents into the detection wells, where bioassay steps are executed. Another of the distinguished characteristics of the demonstrated system is its ability to aspirate the fluid from the detection wells into the waste reservoir. Therefore, the demonstrated automated platform has the ability to execute even the most complex multi-step assays where dilution and multiple washes are required. Optimization of 3D-printer settings and ways to control leakages typical of FDM-printed fluidic systems are also discussed. Full article
(This article belongs to the Special Issue Additive Manufacturing for Medical Applications)
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Open AccessArticle Design and Near-Infrared Actuation of a Gold Nanorod–Polymer Microelectromechanical Device for On-Demand Drug Delivery
Micromachines 2018, 9(1), 28; https://doi.org/10.3390/mi9010028
Received: 18 December 2017 / Revised: 7 January 2018 / Accepted: 11 January 2018 / Published: 13 January 2018
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Abstract
Polymeric drug delivery systems usually deliver drugs by diffusion with an initial burst of release followed by a slower prolonged release phase. An optimal system would release exact doses of drugs using an on-demand external actuation system. The purpose of this study was
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Polymeric drug delivery systems usually deliver drugs by diffusion with an initial burst of release followed by a slower prolonged release phase. An optimal system would release exact doses of drugs using an on-demand external actuation system. The purpose of this study was to design and characterize a novel drug-delivery device that utilizes near infrared (NIR 800 nm) laser-actuated drug release. The device was constructed from biocompatible polymers comprising a reservoir of drug covered by an elastic perforated diaphragm composed of a bilayer of two polymers with different thermal expansion coefficients (ethylenevinylacetate (EVA) and polydimethylsiloxane (PDMS) containing gold nanoparticles). Upon illumination with a NIR laser, the gold nanoparticles rapidly heated the bilayer resulting in bending and a drug-pumping action through the perforated bilayer, following sequential laser-actuation cycles. Devices filled with the anti-proliferative drug docetaxel were seen to release only small amounts of drug by diffusion but to release large and reproducible amounts of drug over 20 s laser-actuation periods. Because NIR 800 nm is tissue-penetrating without heating tissue, suitable geometry drug-delivery devices might be implanted in the body to be actuated by an externally applied NIR laser to allow for on-demand exact drug dosing in vivo. Full article
(This article belongs to the Special Issue Biomedical Microdevices: Design, Fabrication and Application)
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