Scholarly Publications - UNAM
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Item Open Access Microfluidics-integrated microwave sensors for single cells size discrimination(Institute of Electrical and Electronics Engineers, 2021-04) Seçme, Arda; Pisheh, Hadi Sedaghat; Uslu, H. Dilara; Akbulut, Özge; Erdoğan, R. Tufan; Hanay, Mehmet SelimThe size of a cell is one of the most fundamental biophysical parameters it possesses. Traditionally size measurements are done by using optical microscopy and quantitative phase imaging. However, a sensor with higher resolution, high throughput and lower cost is still needed. Here, a novel microfluidics-integrated microwave sensor is demonstrated to characterize single cells in real-time without labelling. Coplanar waveguide resonator is designed with a bowtie-shaped sensing electrodes separated by 50 μm. Cells are transported to sensing region by microfluidic channels and their sizes are measured simultaneously by the microwave sensors and optical microscopy. To enhance the microwave resolution, the microwave resonator is equipped with external heterodyne measurement circuitry detecting each and every cell passing through the sensing region. By comparing quantitative microscopic image analysis with frequency shifts, we show that microwave sensors can effectively measure cellular size. Our results indicate that microfluidics-integrated microwave sensors (MIMS) can be used for detecting.Item Open Access Detection of single gold nanoparticle in liquid with nanopore-integrated microwave resonators(Institute of Electrical and Electronics Engineers, 2021-04-01) Pisheh, Hadi Sedaghat; Seçme, Arda; Uslu, H. Dilara; Küçükoğlu, Berk; Hanay, Mehmet SelimHere, we propose a nanopore integrated microwave resonator to detect single nanoparticles in real time. In contrast to existing nanopore-sensors relying on detection techniques like resistive pulse sensing, and current-voltage measurements, the presented coplanar-waveguide sensor detects the passage of gold nanoparticles through a nanopore on a thin film membrane. Resonance frequency of the sensor, which is around 7 GHz, is tracked by a custom-built close loop circuitry. Gold nanoparticles are electro kinetically driven through the pore: as each nanoparticle passed the pore, it induces a shift in the resonance frequency of the resonator. The presented method is not limited by the specific design of the pore, alleviating the stringing condition on pore size and shape with respect to the target analyte.Item Open Access Long-length 3D printed hollow-core polymer optical fiber for wideband light guidance(Academic Press Inc., 2023-09-01) Rahman, Mahmudur; Ordu, MustafaA hollow-core microstructured polymer optical fiber containing a six-pointed star cladding design is directly drawn from a 3D printed preform for wideband light guidance. Fabrication of a complex geometry-based preform is enabled using commercially available translucent polymer filaments in a 3D printer. Light guidance from visible to infrared regions through the core of 57.8 cm long fiber is achieved with a minimum loss of 0.11 dB/cm in the near-infrared spectrum. The bending loss of the proposed design is also investigated to determine the light guidance under a mechanical effect. The modified fabrication process of the polymer optical fiber with novel design could be an alternative to conventional optical fibers for visible and infrared light guidance. © 2023 Elsevier Inc.Item Open Access Rapid photo-bleaching gamma irradiated Yb-doped optical fibers by high-energy ns pulsed laser(Academic Press Inc., 2023-10-25) Kendir Tekgül, Esra; Ortaç, BülendA rapid and efficient photo-bleaching process was demonstrated with a high-energy nanosecond pulse to recover existing and/or revealed color centers on 10 kGy Gamma-irradiated Yb-doped optical fiber. Multi-mJ pulsed laser based on an optical parametric amplifier system operating at wavelengths of 532 nm, 680 nm and 793 nm was used. The photo-bleaching performance is investigated as a function of the wavelength and energy of the pulsed light source. It was observed that the photo-bleaching level of the Yb-doped optical fiber increased when the exposure time of the pulsed laser light and the photon energy was increased. The maximum PB occurred in the pulsed laser of 532 nm wavelength in the optical fiber. Also, a drastically increase in the PB was observed due to the increasing laser energy at the wavelength of 532 nm and 680 nm pulsed laser. The results show that the recovery levels of color centers in the Yb-doped optical fibers could be reached up to 96 % in a shorter time (h) by using the pulsed laser compared to that of the studies using continuous laser. © 2023 Elsevier Inc.Item Embargo Mid-infrared negative curvature hollow-core fiber with elliptically nested tubular structure(Elsevier B.V., 2022-12-24) Khan, Asfandyar; Ordu, MustafaArsenic triselenide chalcogenide negative curvature hollow-core fiber with ellipse-nested tubular cladding elements was numerically presented for the low-loss light guidance in the mid-infrared region. Confinement and total losses were calculated for the fiber with a five-tube design as low as 0.34 dB/km and 4.55 dB/km at 10.6μm, respectively. The single-mode light guidance characteristic of the proposed design was investigated, and a strong suppression on the higher-order modes shows that the fiber design favors the light guidance with the fundamental mode. A dispersion control study was carried out to optimize the primary design parameters to shift the zero-dispersion wavelength close to 10.6μm. The bending loss performance of the proposed design was analyzed in the targeted spectrum. The proposed negative curvature hollow-core fiber could be potentially used in low-loss guidance for high-power lasers and could also be utilized for several other applications, such as surgery and drug delivery in the mid-IR spectrum. © 2022 Elsevier B.V.Item Embargo Phase-shifted bragg-grating consisting of silicon oxynitride doped silicon and silica alternating layers lab-on-fiber for biosensors with ultrahigh sensitivity and ultralow detection limit(Elsevier Ltd, 2023-06-21) Emre Tabaru, Timuçin; Karatutlu, Ali; Ortaç, BülendFabry-Perot (FP) optical fiber sensors are reported to be highly sensitive for detecting various physical, chemical, and biological objects. In this study, an FP-based Phase Shifted Bragg-Grating Lab-on-Fiber (PSBG-LOF) is presented to determine ultralow glucose concentrations in liquids by using a novel PSBG at the end facet of a single-mode fiber (SMF). The proposed LOF consists of an intermediate silica layer sandwiched between two identical PSBGs formed by 4.5 pairs of siliconoxynitrite (SiON) doped silicon (Si), which are newly synthesized silica (SiO2) thin films, all deposited by the plasma enhanced chemical vapor deposition (PECVD) method. The SiON-doped Si molecule group was used for the first time as PSBG structures and LOF of the glucose in liquids. Our findings with the proposed sensors revealed that the sensitivity value was 14904 nm/RIU (4.3 pm/ppm and 4.29 nm/(mg/ml)) and the detection limit was calculated as 1.98 × 10−6 RIU. In addition, the proposed sensor is insensitive to temperature changes in the range of 25°C-45°C. The results are very promising for the in-vivo biosensing applications comprising temperature unresponsive LOF. © 2023 Elsevier LtdItem Embargo The sub-terahertz region absorption of sputter deposited nanoscale TiAlV thin films(Elsevier B.V., 2022-12-05) Öksüzoğlu, Ramis Mustafa; Altan, Hakan; Abdüsselamoğlu, Mehmet Sait; Özkan, Özlem Başak; Bayram, Yasin; Chakar, Erkan SyuleymanAbsorption in the sub-terahertz region in TiAlV thin films with their potential usage in detectors and plasmonic applications is a crucial point for device performance. This work aims to investigate the thickness-dependent evolution of the sub-terahertz region absorption, electrical resistivity in TiAlV thin films deposited by DC magnetron sputtering and to study the structure-property correlation. For structural analyses, X-ray diffraction and transmission electron microscopy techniques have been used. In different deposition conditions, TiAlV thin films indicating the β-Ti phase with anisotropic growth and the hexagonal AlTi3 phase with equiaxial growth have been produced. High resistivity values have been measured in films with the AlTi3 phase. In all TiAlV thin films with different structures, thickness dependent resistivity change in the range 3–23 nm, whereby a strong increase in electrical resistivity with decreasing film thickness have been observed below a thickness of 6 nm. The sub-terahertz absorption increases with increasing film thickness. The highest terahertz region absorption has been found for the films with the β-Ti phase and anisotropic growth also indicating higher electrical conductivity, which favors absorption sensitive applications in the terahertz region. © 2022 Elsevier B.V.Item Open Access Controlling the photoluminescence of quantum emitters in hexagonal boron nitride by external magnetic fields(IOP Publishing, 2022-10-28) Korkut, Hilal; Sarpkaya, İbrahimThe recent observation of room temperature spin-dependent photoluminescence (PL) emission from hexagonal boron nitride's (h-BN's) defect centers motivates for performing a complementary low-temperature photophysical study of quantum emitters under relatively high magnetic fields. Here, we investigate the PL emission dynamics of h-BN's visible single-photon emitters under an applied out-of-plane magnetic field at cryogenic temperatures. The PL intensity of the emitters in our work strikingly exhibits strong magnetic field dependence and decreases with the increased magnetic field. A substantial decrease in the integrated PL intensity of the emitters by up to one order of magnitude was observed when the applied field is increased from 0 T to 7 T. The observed reversible photodarkening of PL emission due to the applied magnetic field is in very well agreement with the predictions of a recent joint experimental and theoretical study and can happen only if the spin-selective, non-radiative, and asymmetric intersystem crossing transitions proceed from the triplet excited state to the lowest-lying spin-singlet metastable state and from the metastable state to the triplet ground state. Our results not only shed more light on the light emission paths of defect centers in h-BN but also show the use of the magnetic field as an efficient control knob in the development of magneto-optical devices.Item Embargo Zirconia nanoparticle coating for high-strength and alkali-resistant glass fibers(Elsevier B.V., 2023-08-16) Behboud, Ali Bagheri; Ahmed, Md Kawsar; Kurucu, Arda; Çömlekçi, G. K.; Ordu, MustafaIn this study, the effect of zirconia nanoparticle coating on the chemical and mechanical characteristics of E-glass fibers was investigated for usage in an alkaline environment. E-glass fibers were dip-coated in aqueous zirconia nanoparticle solutions that have varying concentrations of nanoparticles. Tensile tests were conducted on bare and coated fibers to determine the impact of nanoparticles on the strength of fibers. According to the mechanical analysis, the tensile strengths of the fibers were enhanced by 10.2%, 12.2%, 14.6%, and 17.4% for 5%, 10%, 15%, and 20% of nanoparticles in the solutions, respectively. The role of zirconia coating on the alkali resistance of fibers was investigated in a NaOH-based alkaline solution. Zirconia nanoparticle-coated fibers with 15% and 20% solutions were not corroded in the alkaline environment after dwelling for 500 h. The coating also prevented the degradation of mechanical properties, and the aged fibers maintained similar tensile characteristics.Item Open Access Formation and thermo-physical properties of aerogel ceramic blanket composites synthesized via scalable atmospheric pressure process with methyltrimethoxysilane precursor(Springer, 2023-09-28) Tav, A.; Öz, Y.; Akyıldız, Halil İbrahimThe fragility of silica-based aerogels limits their potential use in various applications. These exceptional materials can be immobilized on more flexible insulation materials to form materials called ‘aerogel blankets’. In situ, sol-gel deposition is one way to synthesize aerogel material directly on the fibrous matrix. This study presents aerogel blankets’ formation and thermophysical performance obtained by in situ deposition of a methyltrimethoxysilane (MTMS) precursor prepared with sodium dodecyl sulphate surfactants. X-ray diffraction analysis indicates increased peak intensities, suggesting a more organized crystalline-like structure. Corresponding Raman spectroscopy and transmission electron microscopy (TEM) observations corroborate the results, highlighting the surfactant’s role in promoting structural order within the aerogel. A distinct silica spherical structure was also observed in the TEM analysis. The process was carried out at ambient pressure conditions; thus, the process is scalable for large-volume production. The MTMS concentration of the sol varied in the range of 5 to 30 wt.%, resulting in different aerogel characteristics deposited onto the ceramic fiber matrix. Samples were characterized mainly for their thermal, mechanical, and morphological properties. Remarkably, the thermal conductivity performance of the obtained composite blanket showed 30% lower heat conductivity than the pristine ceramic blanket.Item Open Access Origins of the photocatalytic NOx oxidation and storage selectivity of mixed metal oxide photocatalysts: prevalence of electron-mediated routes, surface area, and basicity(American Chemical Society, 2024-01-23) Ebrahimi, Elnaz; Irfan, Muhammad; Koçak, Yusuf; Rostas, A. M.; Erdem, E.; Özensoy, EmrahMgO, CaO, SrO, or BaO-promoted TiO2/Al2O3 was utilized in the photocatalytic NOx oxidation and storage reaction. Photocatalytic performance was investigated as a function of catalyst formulation, calcination temperature, and relative humidity. Onset of the photocatalytic activity in TiO2/Al2O3 coincides with the transition from the anatase to rutile phase and increasing number of paramagnetic active centers and oxygen vacancies. Disordered AlOx domains enable the formation of oxygen vacancies and paramagnetic centers on titania domains, hindering the nucleation and growth of titania particles, as well as increasing specific surface area (SSA) to store oxidized NOx species away from titania active sites. Both e-- and h+-mediated pathways contribute to photocatalytic NO conversion. Experiments performed using an e- scavenger (i.e., H2O2), suppressing the e--mediated route, attenuated the photocatalytic selectivity by triggering NO2(g) release. Superior NOx storage selectivity of 7.0Ti/Al-700 as compared to other TiO2/Al2O3 systems in the literature was attributed to an interplay between the presence of electrons trapped at oxygen vacancies and superoxide species allowing a direct pathway for the complete NO oxidation to HNO3/NO3- species, and the relatively large SSA of the photocatalyst prevents the rapid saturation of the photocatalyst with oxidation products. Longevity of the 7.0Ti/Al-700 was improved by the incorporation of CaO, emphasizing the importance of the surface basicity of the NOx storage sites.Item Embargo A machine learning approach for the estimation of photocatalytic activity of ALD ZnO thin films on fabric substrates(Elsevier, 2024-02-01) Akyıldız, Halil I.; Yiğit, E.; Arat, A. B.; Islam, S.Research in the field of photocatalytic wastewater treatment is striving to enhance catalyst materials to achieve high-performance systems. A promising approach to this goal has been immobilizing photocatalytic materials on fibrous substrates via atomic layer deposition (ALD). Nevertheless, both the ALD process and the assessment of photocatalytic performance involve a multitude of parameters necessitating thorough investigation. In this study, we employ popular machine-learning algorithms, including Support Vector Regression (SVR) and Artificial Neural Networks (ANN), to predict the photocatalytic activity of ALD-coated textiles. The photocatalytic activity is evaluated through methylene blue and methyl orange degradation tests. Machine learning algorithms are tested and trained using the k-fold cross-validation technique. The findings demonstrate that the ANN and SVR methods utilized in this research can predict catalytic activity with mean absolute percentage errors (MAPE) of 2.35 and 3.25, respectively. This study illuminates that, within the defined range of process parameters, the photocatalytic activity of ALD-coated textiles can be precisely estimated with suitable machine-learning algorithms.Item Open Access Experimental and ab-initio investigation of the electrical conductivity of emeraldine salt(American Chemical Society, 2023-03-31) Ergönenç Yavas, Z.; Cevher, D.; Silis, H. T.; Cirpan, A.; Gülseren, Oğuz; Franchini, C.We present an experimental and first-principles study to describe the changes in the electrical conductivity properties of the Emeraldine Salt (ES) form of polyaniline when using two different synthesis methods. The ES powders obtained by the interfacial synthesis method (PANI-I) exhibit higher electrical conductivity than that of the powders obtained by the conventional method (PANI-C). Investigation of the calculated band structure and density of states together with experimentally obtained optical-absorption spectra and the magnetic measurements indicate that PANI-I differs from PANI-C with respect to its localized defect state type which significantly alters the intrinsic conductivity. Furthermore, comparative studies of bond length, dihedral angles, and relative stabilities of Leucomeraldine Base, Emeraldine Base, ES Bipolaron state (ESB), and Polaron state (ESP) indicate that ESB and ESP states might coexist. Additionally, we confirm that increasing the length of the polymer chain to octamer in the unit cell does not influence the relative stability between ESB and ESP defect states.Item Embargo Histopathology of chironomids exposed to fly ash and microplastics as a new biomarker of ecotoxicological assessment(Elsevier BV, 2023-12-10) Stojanović, J.; Savić-Zdravković, D.; Jovanović, B.; Vitorović, J.; Bašić, J.; Stojanović, I.; Žabar Popović, A.; Duran, Hatice; Kračun Kolarević, M.; Milošević, Đ.Histopathology of chironomids exposed to fly ash and microplastics as a new biomarker of ecotoxicological assessment In the last few decades, industrial pollution has gained extensive attention in terms of its effect on the aquatic environment. This imposes the need to develop sensitive biomarkers for early detection of pollutant toxicity in ecotoxicological assessment. The advantages of histopathological biomarkers are many, including quick reaction to the presence of contaminants, and the small number of individuals needed for efficient analysis. The present study analyzed the negative effect of lignite coal fly ash (LCFA) and microplastic particles (MPs) on Chironomus riparius, a suggested model organism by the Organization for Economic Cooperation and Development (OECD). This study aimed to perform histological analyses of larval tissues and target potential changes in treated groups that could serve as promising histopathological biomarkers of the contaminant's negative effects. Following that, other known sensitive sub-organismal biomarkers were analyzed and paired with the histopathological ones. Histological analysis of larvae showed a significantly decreased length of microvilli in midgut regions II and III in both treatments. Treatments with MPs affected oxidative stress parameters: thiobarbituric acid reactive substances (TBARS), advanced oxidation protein products (AOPP), superoxide dismutase (SOD), and hemoglobin levels, while LCFA significantly affected all tested sub-organismal biomarkers (DNA damage, levels of AOPP, SOD, and hemoglobin), except catalase (CAT) and TBARS. When observing histological slides, a significant shortage of brush border length in the posterior parts of the midgut was detected in all treatments. In the case of LCFA, the appearance of intensive vacuolization of digestive cells with inclusions resembling apoptotic bodies, in mentioned regions was also detected. This study demonstrated high sensitivity of brush border length to the MPs and LCFA exposure, complementary to other tested sub-organismal biomarkers. Revealing the great potential of this histopathological biomarker in ecotoxicological studies contributes to the international standard ecotoxicology assessment of emerging pollutants.Item Open Access Formulation of a fast-disintegrating drug delivery system from cyclodextrin/naproxen inclusion complex nanofibrous films(Royal Society of Chemistry, 2023-12-21) Celebioglu, Asli; Dash, Kareena; Aboelkheir, Mahmoud; Kilic, Mehmet E.; Durgun, Engin; Uyar, TamerFormulation of a fast-disintegrating drug delivery system from cyclodextrin/naproxen inclusion complex nanofibrous films Naproxen is a well-known non-steroidal anti-inflammatory drug (NSAID) that suffers from limited water solubility. The inclusion complexation with cyclodextrin (CD) can eliminate this drawback and the free-standing nanofibrous film (NF) generated from these inclusion complexes (ICs) can be a promising alternative formula as an orally disintegrating drug delivery system. For this, naproxen/CD IC NFs were generated using the highly water soluble hydroxypropylated derivative of βCD (HPβCD) with two different molar ratios of 1/1 and 1/2 (drug/CD). The complexation energy calculated by the modeling study demonstrated a more favorable interaction between HPβCD and naproxen for the 1/2 molar ratio than 1/1. HPβCD/naproxen IC NFs were generated with loading concentrations of ∼7–11% and without using toxic chemicals. HPβCD/naproxen IC NFs indicated a faster and enhanced release profile in aqueous medium compared to pure naproxen owing to inclusion complexation. Moreover, rapid disintegration in less than a second was achieved in an artificial saliva environment.Item Open Access Understanding the suitable alloying conditions for highly efficient Cu- and Mn-doped Zn1-xCdxS/ZnS core-shell quantum dots(Elsevier B.V., 2023-10-20) Kaur, Manpreet; Sharma, Ashma; Erdem, Onur; Kumar, A.; Demir, Hilmi Volkan; Sharma, M.Doping of alloyed colloidal quantum dots (QDs) has garnered significant attention for providing tunable and Stokes-shifted emission. By alloying the host semiconductor nanocrystals (NCs), their band gap can be tuned. With the specific addition of dopant ions, these NCs can emit tunable emissions within the visible spectrum. However, while doped and alloyed quantum dots (QDs) have shown promise for tunable emissions, their emission qualities have not been consistent across the spectrum. Here, we report the synthesis of high-quality Cu- and Mn-doped ZnxCd1-xS (x = 0–1) alloyed QDs by a colloidal non-injection method. In this study, we examined the effect of different dopant ions on the optical properties of similar alloyed nanocrystals. The deposition of a ZnS shell on these doped QDs significantly improves their quantum yield (QY), increasing it from 7.0 % to 50.0 % for Cu-doped QDs and from 30.0 % to 80.0 % for Mn-doped QDs. The Cu-doped QDs exhibit tunable emission from green to red across the visible spectrum by varying the Zn/Cd ratio, whereas the Mn-doped QDs show a fixed orange emission. Interestingly, the Cu-doped alloyed QDs show a contrasting trend in quantum yield (QY) compared to those of Mn-doped QDs when the amount of Cd in ZnCdS alloyed QDs is systematically changed. As the amount of Cd increases in the ZnCdS alloyed QDs, the Cu-doped QDs show both an increase in average lifetime and an increase in QY. In contrast, for the Mn-doped QDs, the decay lifetime values remain fairly constant for different amounts of Cd in the ZnCdS alloyed QDs, but the QY decreases as the amount of Cd increases. The results of this study may facilitate the design of optimal alloying combinations for Cu/Mn-doped QDs in optoelectronic applications. © 2023 The AuthorsItem Open Access Deep-learning-enabled electromagnetic near-field prediction and inverse design of metasurfaces(Optica Publishing Group (formerly OSA), 2023-10-16) Kanmaz, Tevfik Bülent; Öztürk, E.; Demir, Hilmi Volkan; Gündüz-Demir, Ç.Metasurfaces generate desired electromagnetic wavefronts using sub-wavelength structures that are much thinner than conventional optical tools.However, their typical design method is based on trial and error, which is adversely inefficient in terms of the consumed time and computational power. This paper proposes and demonstrates deep-learning-enabled rapid prediction of the full electromagnetic near-field response and inverse prediction of the metasurfaces from desired wavefronts to obtain direct and rapid designs. The proposed encoder-decoder neural network was tested for different metasurface design configurations. This approach overcomes the common issue of predicting only the transmission spectra, a critical limitation of the previous reports of deep-learning-based solutions. Our deep-learning-empowered near-field model can conveniently be used as a rapid simulation tool for metasurface analyses as well as for their direct rapid design. © 2023 Optica Publishing Group.Item Open Access Prolonged dephasing time of ensemble of moiré-trapped interlayer excitons in WSe2-MoSe2 heterobilayers(Nature Research, 2023-09-11) Durmuş, Mehmet Atıf; Demiralay, Kaan; Khan, Muhammad Mansoor; Atalay, Şeyma Esra; Sarpkaya, IbrahimThe moiré superlattices of transition metal dichalcogenide heterobilayers have a pronounced effect on the optical properties of interlayer excitons (IXs) and have been intensively studied in recent years. However, the impact of moiré potentials on the temporal coherence of the IXs has not yet been investigated in detail. Here, we systematically investigate the coherence properties of both the ensemble of delocalized and the ensemble of localized IXs trapped in moiré potentials of the hexagonal boron nitride encapsulated WSe2-MoSe2 heterostructures. Our low-temperature first-order correlation measurements show that prolonged T 2 dephasing times with values up to 730 fs can be obtained from the ensemble of localized IXs under moderate pump powers. We observed up to almost a five-fold increase over the values we obtained from the delocalized IXs, while more than two-fold over the previously reported values of T 2 ~ 300 fs from the delocalized IXs. The prolonged values of T 2 dephasing times and narrow photoluminescence (PL) linewidths for the ensemble of moiré-trapped IXs compared to delocalized one indicate that dephasing mechanisms caused by exciton-low energy acoustic phonon and exciton-exciton scattering are significantly suppressed due to the presence of localization potentials. Our pump power-dependent T 2 results show that ultra-long dephasing times can be expected if the dephasing time measurements are performed with the narrow photoluminescence emission line of a single moiré-trapped IX at a low pump power regime. The prolonged values of IX dephasing times would be critical for the applications of quantum information science and the development of two-dimensional material-based nanolasers. © 2023, Springer Nature Limited.Item Open Access Single-material MoS2 thermoelectric junction enabled by substrate engineering(Nature Research, 2023-05-26) Razeghi, Mohammadali; Spiece, J.; Oğuz, Oğuzhan; Pehlivanoğlu, Doruk; Huang, Y.; Sheraz, Ali; Başçı, U.; Dobson, P. S.; Weaver, J. M. R.; Gehring, P.; Kasırga, Talip SerkanTo realize a thermoelectric power generator, typically, a junction between two materials with different Seebeck coefficients needs to be fabricated. Such differences in Seebeck coefficients can be induced by doping, which renders it difficult when working with two-dimensional (2d) materials. However, doping is not the only way to modulate the Seebeck coefficient of a 2d material. Substrate-altered electron–phonon scattering mechanisms can also be used to this end. Here, we employ the substrate effects to form a thermoelectric junction in ultrathin, few-layer MoS2 films. We investigated the junctions with a combination of scanning photocurrent microscopy and scanning thermal microscopy. This allows us to reveal that thermoelectric junctions form across the substrate-engineered parts. We attribute this to a gating effect induced by interfacial charges in combination with alterations in the electron–phonon scattering mechanisms. This work demonstrates that substrate engineering is a promising strategy for developing future compact thin-film thermoelectric power generators. © 2023, The Author(s).Item Open Access In situ synthesis and dynamic simulation of molecularly imprinted polymeric nanoparticles on a micro-reactor system(Nature Research, 2023-08-10) Erdem, Özgecan; Eş, Ismail; Saylan, Y.; Atabay, Maryam; Güngen, Murat Alp; Ölmez, Kadriye; Denizli, A.; İnci, FatihCurrent practices in synthesizing molecularly imprinted polymers face challenges—lengthy process, low-productivity, the need for expensive and sophisticated equipment, and they cannot be controlled in situ synthesis. Herein, we present a micro-reactor for in situ and continuously synthesizing trillions of molecularly imprinted polymeric nanoparticles that contain molecular fingerprints of bovine serum albumin in a short period of time (5-30 min). Initially, we performed COMSOL simulation to analyze mixing efficiency with altering flow rates, and experimentally validated the platform for synthesizing nanoparticles with sizes ranging from 52-106 nm. Molecular interactions between monomers and protein were also examined by molecular docking and dynamics simulations. Afterwards, we benchmarked the micro-reactor parameters through dispersity and concentration of molecularly imprinted polymers using principal component analysis. Sensing assets of molecularly imprinted polymers were examined on a metamaterial sensor, resulting in 81% of precision with high selectivity (4.5 times), and three cycles of consecutive use. Overall, our micro-reactor stood out for its high productivity (48-288 times improvement in assay-time and 2 times improvement in reagent volume), enabling to produce 1.4-1.5 times more MIPs at one-single step, and continuous production compared to conventional strategy. © 2023, Springer Nature Limited.