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Journal articleYin Y, Xiao G, Zhang K, et al., 2019,
Tacrolimus- and Nerve Growth Factor-Treated Allografts for Neural Tissue Regeneration
, ACS CHEMICAL NEUROSCIENCE, Vol: 10, Pages: 1411-1419, ISSN: 1948-7193 -
Journal articleCoskun AF, Topkaya SN, Yetisen AK, et al., 2019,
Portable multiplex optical assays
, Advanced Optical Materials, Vol: 7, Pages: 1-25, ISSN: 2195-1071Global health issues are increasingly becoming critical with high fatality rate due to chronic and infectious diseases. Emerging technologies aim to address these problems by understanding the causes of lethal conditions and diagnosing symptoms at early stage. Existing commercial diagnostics primarily focus on single-plex assays due to ease-of-use, simplicity in analysis, and amenability to mass manufacturing. Many research grade devices have utilized only a few molecular and morphological signatures in bodily fluids. However, multiplex devices can improve accuracy, sensitivity, and scalability of research and diagnostic devices. This review presents multiplex assays that utilize optical, electrical, and chemical methods and materials that have the potential to improve portable point-of-care diagnostics. The critical role of emerging optical and complementary assays with multiple contrast mechanisms is investigated to enable highly multiplex analysis in field settings. Multiparameter portable devices for field applications toward health monitoring, food testing, air quality monitoring, and microanalysis in other extreme conditions are examined. Current trends indicate the need for validation of health diagnosis based on a large number of biomarkers in randomized clinical trials. Advanced digital analysis, crowd-sourced solutions, and robust user interfaces will become an integral part of the connected global health systems and personalized monitoring platforms.
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Journal articleDong J, Wang S, Lu M, et al., 2019,
Real-time dual-sensitive shearography for simultaneous in-plane and out-of-plane strain measurements
, Optics Express, Vol: 27, Pages: 3276-3283, ISSN: 1094-4087A real-time, dual-sensitive shearography system using a single-wavelength laser was developed for simultaneous and dynamic in-plane and out-of-plane strain measurements. The shearography system is capable of measuring crack-tip deformation fields quantitatively. A spatial multiplexing technique based on Fourier transform is employed for simultaneous and dynamic multi-component phase retrieval. Two slit spatial filters and a common-path shearing interferometer are used to obtain an improved phase quality for crack-tip deformation measurements. Mode-I fracture experiments under three-point bending were conducted to validate the feasibility and the capability of this method.
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Journal articleYetisen AK, Martinez-Hurtado JL, Uenal B, et al., 2018,
Wearables in medicine
, Advanced Materials, Vol: 30, Pages: 1-26, ISSN: 0935-9648Wearables as medical technologies are becoming an integral part of personal analytics, measuring physical status, recording physiological parameters, or informing schedule for medication. These continuously evolving technology platforms do not only promise to help people pursue a healthier life style, but also provide continuous medical data for actively tracking metabolic status, diagnosis, and treatment. Advances in the miniaturization of flexible electronics, electrochemical biosensors, microfluidics, and artificial intelligence algorithms have led to wearable devices that can generate real-time medical data within the Internet of things. These flexible devices can be configured to make conformal contact with epidermal, ocular, intracochlear, and dental interfaces to collect biochemical or electrophysiological signals. This article discusses consumer trends in wearable electronics, commercial and emerging devices, and fabrication methods. It also reviews real-time monitoring of vital signs using biosensors, stimuli-responsive materials for drug delivery, and closed-loop theranostic systems. It covers future challenges in augmented, virtual, and mixed reality, communication modes, energy management, displays, conformity, and data safety. The development of patient-oriented wearable technologies and their incorporation in randomized clinical trials will facilitate the design of safe and effective approaches.
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Journal articleYetisen AK, 2018,
Biohacking
, Trends in Biotechnology, Vol: 36, Pages: 744-747, ISSN: 0167-7799Biohacking is a do-it-yourself citizen science merging body modification with technology. The motivations of biohackers include cybernetic exploration, personal data acquisition, and advocating for privacy rights and open-source medicine. The emergence of a biohacking community has influenced discussions of cultural values, medical ethics, safety, and consent in transhumanist technology.
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Journal articleAlQattan B, Yetisen AK, Butt H, 2018,
Direct laser writing of nanophotonic structures on contact lenses
, ACS Nano, Vol: 12, Pages: 5130-5140, ISSN: 1936-0851Contact lenses are ubiquitous biomedical devices used for vision correction and cosmetic purposes. Their application as quantitative analytical devices is highly promising for point-of-care diagnostics. However, it is a challenge to integrate nanoscale features into commercial contact lenses for application in low-cost biosensors. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm, 3 ns pulse, 240 mJ) in holographic interference patterning mode was utilized to produce optical nanostructures over the surface of a hydrogel contact lens. One-dimensional (925 nm) and two-dimensional (925 nm × 925 nm) nanostructures were produced on contact lenses and analyzed by spectroscopy and angle-resolve measurements. The holographic properties of these nanostructures were tested in ambient moisture, fully hydrated, and artificial tear conditions. The measurements showed a rapid tuning of optical diffraction from these nanostructures from 41 to 48°. The nanostructures were patterned near the edges of the contact lens to avoid any interference and obstruction to the human vision. The formation of 2D nanostructures on lenses increased the diffraction efficiency by more than 10%. The versatility of the holographic laser ablation method was demonstrated by producing four different 2D nanopattern geometries on contact lenses. Hydrophobicity of the contact lens was characterized by contact angle measurements, which increased from 59.0° at pristine condition to 62.5° at post-nanofabrication. The holographic nanostructures on the contact lens were used to sense the concentration of Na+ ions. Artificial tear solution was used to simulate the conditions in dry eye syndrome, and nanostructures on the contact lenses were used to detect the electrolyte concentration changes (±47 mmol L–1). Nanopatterns on a contact lens may be used to sense other ocular diseases in early stages at point-of-care settings.
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Journal articleElsherif M, Hassan MU, Yetisen AK, et al., 2018,
Wearable contact lens biosensors for continuous glucose monitoring using smartphones
, ACS Nano, Vol: 12, Pages: 5452-5462, ISSN: 1936-0851Low-cost, robust, and reusable continuous glucose monitoring systems that can provide quantitative measurements at point-of-care settings is an unmet medical need. Optical glucose sensors require complex and time-consuming fabrication processes, and their readouts are not practical for quantitative analyses. Here, a wearable contact lens optical sensor was created for the continuous quantification of glucose at physiological conditions, simplifying the fabrication process and facilitating smartphone readouts. A photonic microstructure having a periodicity of 1.6 μm was printed on a glucose-selective hydrogel film functionalized with phenylboronic acid. Upon binding with glucose, the microstructure volume swelled, which modulated the periodicity constant. The resulting change in the Bragg diffraction modulated the space between zero- and first-order spots. A correlation was established between the periodicity constant and glucose concentration within 0–50 mM. The sensitivity of the sensor was 12 nm mM–1, and the saturation response time was less than 30 min. The sensor was integrated with commercial contact lenses and utilized for continuous glucose monitoring using smartphone camera readouts. The reflected power of the first-order diffraction was measured via a smartphone application and correlated to the glucose concentrations. A short response time of 3 s and a saturation time of 4 min was achieved in the continuous monitoring mode. Glucose-sensitive photonic microstructures may have applications in point-of-care continuous monitoring devices and diagnostics at home settings.
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Journal articleBadawy A-R, Hassan MU, Elsherif M, et al., 2018,
Contact lenses for color blindness
, Advanced Healthcare Materials, Vol: 7, Pages: 1-7, ISSN: 2192-2640Color vision deficiency (color blindness) is an inherited genetic ocular disorder. While no cure for this disorder currently exists, several methods can be used to increase the color perception of those affected. One such method is the use of color filtering glasses which are based on Bragg filters. While these glasses are effective, they are high cost, bulky, and incompatible with other vision correction eyeglasses. In this work, a rhodamine derivative is incorporated in commercial contact lenses to filter out the specific wavelength bands (≈545–575 nm) to correct color vision blindness. The biocompatibility assessment of the dyed contact lenses in human corneal fibroblasts and human corneal epithelial cells shows no toxicity and cell viability remains at 99% after 72 h. This study demonstrates the potential of the dyed contact lenses in wavelength filtering and color vision deficiency management.
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Journal articleJiang N, Butt H, Montelongo Y, et al., 2018,
Laser Interference Lithography for the Nanofabrication of Stimuli-Responsive Bragg Stacks
, ADVANCED FUNCTIONAL MATERIALS, Vol: 28, ISSN: 1616-301X -
Journal articleJiang N, Ying G-L, Yetisen AK, et al., 2018,
A bilayered nanoshell for durable protection of single yeast cells against multiple, simultaneous hostile stimuli
, Chemical Science, Vol: 9, ISSN: 2041-6520Single cell surface engineering provides the most efficient, non-genetic strategy to enhance cell stability. However, it remains a huge challenge to improve cell stability in complex artificial environments. Here, a soft biohybrid interfacial layer is fabricated on individual living-cell surfaces by their exposure to a suspension of gold nanoparticles and L-cysteine to form a protecting functional layer to which porous silica layers were bound yielding pores with a diameter of 3.9 nm. The living cells within the bilayered nanoshells maintained high viability (96 ± 2%) as demonstrated by agar plating, even after five cycles of simultaneous exposure to high temperature (40 °C), lyticase and UV light. Moreover, yeast cells encapsulated in bilayered nanoshells were more recyclable than native cells due to nutrient storage in the shell.
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Journal articleYi J, Jiang N, Li B, et al., 2018,
Painful terminal neuroma prevention by capping PRGD/PDLLA conduit in rat sciatic nerves
, Advanced Science, Vol: 5, Pages: 1-11, ISSN: 2198-3844Neuroma formation after amputation as a long-term deficiency leads to spontaneous neuropathic pain that reduces quality of life of patients. To prevent neuroma formation, capping techniques are implemented as effective treatments. However, an ideal, biocompatible material covering the nerves is an unmet clinical need. In this study, biocompatible characteristics presented by the poly(D,L-lactic acid)/arginylglycylaspartic acid (RGD peptide) modification of poly{(lactic acid)-co- [(glycolic acid)-alt-(L-lysine)]} (PRGD/PDLLA) are evaluated as a nerve conduit. After being capped on the rat sciatic nerve stump in vivo, rodent behaviors and tissue structures are compared via autotomy scoring and histological analyses. The PRGD/PDLLA capped group gains lower autotomy score and improves the recovery, where inflammatory infiltrations and excessive collagen deposition are defeated. Transmission electron microscopy images of the regeneration of myelin sheath in both groups show that abnormal myelination is only present in the uncapped rats. Changes in related genes (MPZ, MBP, MAG, and Krox20) are monitored quantitative real-time polymerase chain reaction (qRT-PCR) for mechanism investigation. The PRGD/PDLLA capping conduits not only act as physical barriers to inhibit the invasion of inflammatory infiltration in the scar tissue but also provide a suitable microenvironment for promoting nerve repairing and avoiding neuroma formation during nerve recovery.
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Journal articleAlqurashi Y, Bajgrowicz-Cieslak M, Hassan MU, et al., 2018,
Laser-Induced Surface Modification of Contact Lenses
, ADVANCED ENGINEERING MATERIALS, Vol: 20, ISSN: 1438-1656 -
Journal articleRashid I, Hassan MU, Khandwalla A, et al., 2018,
Structural Coloration in Caloenas Nicobarica Pigeons and Refractive Index Modulated Sensing
, ADVANCED OPTICAL MATERIALS, Vol: 6, ISSN: 2195-1071 -
Journal articleLiu Q, Jiang N, Liu D, et al., 2018,
Monodispersed silk fibroin microdroplets for protein stabilization
, Applied Physics Letters, Vol: 112, Pages: 1-4, ISSN: 0003-6951Low stability of globular protein droplets in emulsion significantly limits their applications in drug encapsulation, long-term storage, and controlled drug release. Here, a microfluidic flow-focusing device was utilized to synthesize horseradish peroxidase (HRP)-loaded silk fibroin microdroplets. The two immiscible streams of microfluidic flow-focusing were regenerated by silk fibroin solution and a mixture of 95 wt. % sunflower oil and 5 wt. % span 80 as the dispersed and continuous phases, respectively. In this study, the water-in-oil silk fibroin microdroplets were homogeneously produced by leveraging the discrete and periodic breakup of microdroplets and regulating the flow rates. Moreover, the result showed that the stability of encapsulated HRP in microdroplets was 25% higher than that of HRP after 6 weeks incubation. Thus, the microfluidic flow-focusing is a promising technique to form monodisperse microdroplets and maximize the stability of protein droplets.
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Journal articleAlqurashi T, Alhosani A, Dauleh M, et al., 2018,
Laser inscription of pseudorandom structures for microphotonic diffuser applications
, Nanoscale, Vol: 10, Pages: 7095-7107, ISSN: 2040-3364Optical diffusers provide a solution for a variety of applications requiring a Gaussian intensity distribution including imaging systems, biomedical optics, and aerospace. Advances in laser ablation processes have allowed the rapid production of efficient optical diffusers. Here, we demonstrate a novel technique to fabricate high-quality glass optical diffusers with cost-efficiency using a continuous CO2 laser. Surface relief pseudorandom microstructures were patterned on both sides of the glass substrates. A numerical simulation of the temperature distribution showed that the CO2 laser drills a 137 μm hole in the glass for every 2 ms of processing time. FFT simulation was utilized to design predictable optical diffusers. The pseudorandom microstructures were characterized by optical microscopy, Raman spectroscopy, and angle-resolved spectroscopy to assess their chemical properties, optical scattering, transmittance, and polarization response. Increasing laser exposure and the number of diffusing surfaces enhanced the diffusion and homogenized the incident light. The recorded speckle pattern showed high contrast with sharp bright spot free diffusion in the far field view range (250 mm). A model of glass surface peeling was also developed to prevent its occurrence during the fabrication process. The demonstrated method provides an economical approach in fabricating optical glass diffusers in a controlled and predictable manner. The produced optical diffusers have application in fibre optics, LED systems, and spotlights.
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Journal articleKhalid MW, Ahmed R, Yetisen AK, et al., 2018,
Holographic writing of ink-based phase conjugate nanostructures via laser ablation (vol 7, 10603, 2017)
, Scientific Reports, Vol: 8, Pages: 1-1, ISSN: 2045-2322 -
Journal articleJiang N, Montelongo Y, Butt H, et al., 2018,
Microfluidic contact lenses
, Small, Vol: 14, Pages: 1-9, ISSN: 1613-6810Contact lens is a ubiquitous technology used for vision correction and cosmetics. Sensing in contact lenses has emerged as a potential platform for minimally invasive point-of-care diagnostics. Here, a microlithography method is developed to fabricate microconcavities and microchannels in a hydrogel-based contact lens via a combination of laser patterning and embedded templating. Optical microlithography parameters influencing the formation of microconcavities including ablation power (4.3 W) and beam speed (50 mm s−1) are optimized to control the microconcavity depth (100 µm) and diameter (1.5 mm). The fiber templating method allows the production of microchannels having a diameter range of 100–150 µm. Leak-proof microchannel and microconcavity connections in contact lenses are validated through flow testing of artificial tear containing fluorescent microbeads (Ø = 1–2 µm). The microconcavities of contact lenses are functionalized with multiplexed fluorophores (2 µL) to demonstrate optical excitation and emission capability within the visible spectrum. The fabricated microfluidic contact lenses may have applications in ophthalmic monitoring of metabolic disorders at point-of-care settings and controlled drug release for therapeutics.
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Journal articleJiang N, Wang Y, Yin Y-X, et al., 2018,
bFGF and Poly-RGD Cooperatively Establish Biointerface for Stem Cell Adhesion, Proliferation, and Differentiation
, ADVANCED MATERIALS INTERFACES, Vol: 5, ISSN: 2196-7350 -
Journal articleElsherif M, Hassan MU, Yetisen AK, et al., 2018,
Glucose sensing with phenylboronic acid functionalized hydrogel-based optical diffusers
, ACS Nano, Vol: 12, Pages: 2283-2291, ISSN: 1936-0851Phenylboronic acids have emerged as synthetic receptors that can reversibly bind to cis-diols of glucose molecules. The incorporation of phenylboronic acids in hydrogels offers exclusive attributes; for example, the binding process with glucose induces Donnan osmotic pressure resulting in volumetric changes in the matrix. However, their practical applications are hindered because of complex readout approaches and their time-consuming fabrication processes. Here, we demonstrate a microimprinting method to fabricate densely packed concavities in phenylboronic acid functionalized hydrogel films. A microengineered optical diffuser structure was imprinted on a phenylboronic acid based cis-diol recognizing motif prepositioned in a hydrogel film. The diffuser structure engineered on the hydrogel was based on laser-inscribed arrays of imperfect microlenses that focused the incoming light at different focal lengths and direction resulting in a diffused profile of light in transmission and reflection readout modes. The signature of the dimensional modulation was detected in terms of changing focal lengths of the microlenses due to the volumetric expansion of the hydrogel that altered the diffusion spectra and transmitted beam profile. The transmitted optical light spread and intensity through the sensor was measured to determine variation in glucose concentrations at physiological conditions. The sensor was integrated in a contact lens and placed over an artificial eye. Artificial stimulation of variation in glucose concentration allowed quantitative measurements using a smartphone’s photodiode. A smartphone app was utilized to convert the received light intensity to quantitative glucose concentration values. The developed sensing platform offers low cost, rapid fabrication, and easy detection scheme as compared to other optical sensing counterparts. The presented detection scheme may have applications in wearable real-time biomarker monitoring devices at point-of-care
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Journal articleKim H, Beack S, Han S, et al., 2018,
Multifunctional Photonic Nanomaterials for Diagnostic, Therapeutic, and Theranostic Applications
, ADVANCED MATERIALS, Vol: 30, ISSN: 0935-9648 -
Journal articleZhang Z, Dou Q, Gao H, et al., 2018,
30 s Response Time of K+ Ion-Selective Hydrogels Functionalized with 18-Crown-6 Ether Based on QCM Sensor
, ADVANCED HEALTHCARE MATERIALS, Vol: 7, ISSN: 2192-2640 -
Journal articleHassan MU, Liu Y-C, Yetisen AK, et al., 2018,
Energy Landscape of Vertically Anisotropic Polymer Blend Films toward Highly Efficient Polymer Light-Emitting Diodes (PLEDs)
, ADVANCED FUNCTIONAL MATERIALS, Vol: 28, ISSN: 1616-301X -
Journal articleHassaan MU, Liu Y-C, ul Hasan K, et al., 2018,
Highly Efficient Energy Transfer in Light Emissive Poly(9,9-dioctylfluorene) and Poly(p-phenylenevinylene) Blend System
, ACS PHOTONICS, Vol: 5, Pages: 607-613, ISSN: 2330-4022 -
Journal articleGeng W, Wang L, Jiang N, et al., 2018,
Single cells in nanoshells for the functionalization of living cells
, NANOSCALE, Vol: 10, Pages: 3112-3129, ISSN: 2040-3364 -
Journal articleKhalid MW, Ahmed R, Yetisen AK, et al., 2018,
Flexible corner cube retroreflector array for temperature and strain sensing
, RSC Advances: an international journal to further the chemical sciences, Vol: 8, Pages: 7588-7598, ISSN: 2046-2069Optical sensors for detecting temperature and strain play a crucial role in the analysis of environmental conditions and real-time remote sensing. However, the development of a single optical device that can sense temperature and strain simultaneously remains a challenge. Here, a flexible corner cube retroreflector (CCR) array based on passive dual optical sensing (temperature and strain) is demonstrated. A mechanical embossing process was utilised to replicate a three-dimensional (3D) CCR array in a soft flexible polymer film. The fabricated flexible CCR array samples were experimentally characterised through reflection measurements followed by computational modelling. As fabricated samples were illuminated with a monochromatic laser beam (635, 532, and 450 nm), a triangular shape reflection was obtained at the far-field. The fabricated flexible CCR array samples tuned retroreflected light based on external stimuli (temperature and strain as an applied force). For strain and temperature sensing, an applied force and temperature, in the form of weight suspension, and heat flow was applied to alter the replicated CCR surface structure, which in turn changed its optical response. Directional reflection from the heated flexible CCR array surface was also measured with tilt angle variation (max. up to 10°). Soft polymer CCRs may have potential in remote sensing applications, including measuring the temperature in space and in nuclear power stations.
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Journal articleJiang N, Ahmed R, Rifat AA, et al., 2018,
Functionalized Flexible Soft Polymer Optical Fibers for Laser Photomedicine
, ADVANCED OPTICAL MATERIALS, Vol: 6, ISSN: 2195-1071 -
Journal articleAlQattan B, Benton D, Yetisen AK, et al., 2017,
Laser nanopatterning of colored ink thin films for photonic devices
, ACS Applied Materials and Interfaces, Vol: 9, Pages: 39641-39649, ISSN: 1944-8244Nanofabrication through conventional methods such as electron beam writing and photolithography is time-consuming, high cost, complex, and limited in terms of the materials which can be processed. Here, we present the development of a nanosecond Nd:YAG laser (532 nm, 220 mJ) in holographic Denisyuk reflection mode method for creating ablative nanopatterns from thin films of four ink colors (black, red, blue, and brown). We establish the use of ink as a recording medium in different colors and absorption ranges to rapidly produce optical nanostructures in 1D geometries. The gratings produced with four different types of ink had the same periodicity (840 nm); however, they produce distant wavelength dependent diffraction responses to monochromatic and broadband light. The nanostructures of gratings consisting of blue and red inks displayed high diffraction efficiency of certain wavelengths while the black and brown ink based gratings diffracted broadband light. These gratings have high potential to be used as low-cost photonic structures in wavelength-dependent optical filters. We anticipate that the rapid production of gratings based on different ink formulations can enable optics applications such as holographic displays in data storage, light trapping, security systems, and sensors.
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Journal articleDeng S, Jwad T, Li C, et al., 2017,
Carbon nanotube array based binary gabor zone plate lenses
, Scientific Reports, Vol: 7, ISSN: 2045-2322Diffractive zone plates have a wide range of applications from focusing x-ray to extreme UV radiation. The Gabor zone plate, which suppresses the higher-order foci to a pair of conjugate foci, is an attractive alternative to the conventional Fresnel zone plate. In this work, we developed a novel type of Beynon Gabor zone plate based on perfectly absorbing carbon nanotube forest. Lensing performances of 0, 8 and 20 sector Gabor zone plates were experimentally analyzed. Numerical investigations of Beynon Gabor zone plate configurations were in agreement with the experimental results. A high-contrast focal spot having 487 times higher intensity than the average background was obtained.
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Journal articleAlqurashi T, Montelongo Y, Penchev P, et al., 2017,
Correction: Femtosecond laser ablation of transparent microphotonic devices and computer-generated holograms
, Nanoscale, Vol: 9, Pages: 15159-15159, ISSN: 2040-3364 -
Journal articleRashid I, Butt H, Yetisen AK, et al., 2017,
Wavelength-Selective Diffraction from Silica Thin-Film Gratings
, ACS PHOTONICS, Vol: 4, Pages: 2402-2409, ISSN: 2330-4022
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