Recent Submissions

  • On the estimation of landslide intensity, hazard and density via data-driven models

    Di Napoli, Mariano; Tanyas, Hakan; Castro-Camilo, Daniela; Calcaterra, Domenico; Cevasco, Andrea; Di Martire, Diego; Pepe, Giacomo; Brandolini, Pierluigi; Lombardo, Luigi (Natural Hazards, Springer Science and Business Media LLC, 2023-09-12) [Article]
    Maps that attempt to predict landslide occurrences have essentially stayed the same since 1972. In fact, most of the geo-scientific efforts have been dedicated to improve the landslide prediction ability with models that have largely increased their complexity but still have addressed the same binary classification task. In other words, even though the tools have certainly changed and improved in 50 years, the geomorphological community addressed and still mostly addresses landslide prediction via data-driven solutions by estimating whether a given slope is potentially stable or unstable. This concept corresponds to the landslide susceptibility, a paradigm that neglects how many landslides may trigger within a given slope, how large these landslides may be and what proportion of the given slope they may disrupt. The landslide intensity concept summarized how threatening a landslide or a population of landslide in a study area may be. Recently, landslide intensity has been spatially modeled as a function of how many landslides may occur per mapping unit, something, which has later been shown to closely correlate to the planimetric extent of landslides per mapping unit. In this work, we take this observation a step further, as we use the relation between landslide count and planimetric extent to generate maps that predict the aggregated size of landslides per slope, and the proportion of the slope they may affect. Our findings suggest that it may be time for the geoscientific community as a whole, to expand the research efforts beyond the use of susceptibility assessment, in favor of more informative analytical schemes. In fact, our results show that landslide susceptibility can be also reliably estimated (AUC of 0.92 and 0.91 for the goodness-of-fit and prediction skill, respectively) as part of a Log-Gaussian Cox Process model, from which the intensity expressed as count per unit (Pearson correlation coefficient of 0.91 and 0.90 for the goodness-of-fit and prediction skill, respectively) can also be derived and then converted into how large a landslide or several coalescing ones may become, once they trigger and propagate downhill. This chain of landslide intensity, hazard and density may lead to substantially improve decision-making processes related to landslide risk.
  • Materials Design and Applications of N-Type and Ambipolar Organic Electrochemical Transistors

    Lei, Yuqiu; Li, Peiyun; Zheng, Yuting; Lei, Ting (Materials Chemistry Frontiers, Royal Society of Chemistry (RSC), 2023-09-11) [Article]
    Organic electrochemical transistor (OECT) has high transconductance, low operating voltage, and good biocompatibility. It has emerged as a promising technology for chemo/biosensors, bioelectronics, neuromorphic computing, etc. Compared with the abundant high-performance p-type OECT materials, n-type and ambipolar OECT materials are rare and more importantly, their performances lag far behind, which largely limited the development of OECT-based logic circuits. The past few years have witnessed the fast development of n-type and ambipolar OECT materials and their applications, thanks to the efforts of novel material design and device optimization. In this review, we aim to provide an introduction to the working principles of n-type and ambipolar OECTs and survey their recent developments and applications. We will also discuss the challenges and issues that need to be addressed for the future advancement of the field.
  • Iron porphyrin for selective electrochemical reduction of CO2: Synthesis, characterization and effect of electrolyte

    BaQais, Amal; Ait Ahsaine, Hassan (Inorganic Chemistry Communications, Elsevier BV, 2023-09-09) [Article]
    The electrochemical CO2 reduction reaction to form valued by-products is a challenging and a sustainable process. In general, CO2 reduction to carbon neutral fuels requires selective and well-designed catalysts. Herein, we report perfluorinated iron porphyrin (FeFPor) for CO2-to-CO electroreduction in different bicarbonate electrolytes, byproducts distribution in lithium, sodium, potassium and cesium were analyzed. The immobilized FeFPor on the carbon microporous layer of the carbon cloth exhibited a high selectivity for carbon monoxide production over a wide range of potentials from −0.5 to −1 V vs. RHE in all bicarbonate solution with the NaHCO3 being the best catalytic medium. The highest conversion efficiency to CO production reached 97% at −0.5 V vs. RHE in 0.5 M NaHCO3 in near neutral aqueous solution (pH = 7.2). The CO electrosynthesis dropped when using lithium, potassium and cesium bicarbonates, which was due to the CO2 concentration and reactions at the inner electrode-solution reactions.
  • Complex multi-fault rupture and triggering during the 2023 earthquake doublet in southeastern Türkiye

    Liu, Chengli; Lay, Thorne; Wang, Rongjiang; Taymaz, Tuncay; Xie, Zujun; Xiong, Xiong; Irmak, Tahir Serkan; Kahraman, Metin; Erman, Ceyhun (Nature Communications, Springer Science and Business Media LLC, 2023-09-09) [Article]
    Two major earthquakes (MW 7.8 and MW 7.7) ruptured left-lateral strike-slip faults of the East Anatolian Fault Zone (EAFZ) on February 6, 2023, causing >59,000 fatalities and ~$119B in damage in southeastern Türkiye and northwestern Syria. Here we derived kinematic rupture models for the two events by inverting extensive seismic and geodetic observations using complex 5-6 segment fault models constrained by satellite observations and relocated aftershocks. The larger event nucleated on a splay fault, and then propagated bilaterally ~350 km along the main EAFZ strand. The rupture speed varied from 2.5-4.5 km/s, and peak slip was ~8.1 m. 9-h later, the second event ruptured ~160 km along the curved northern EAFZ strand, with early bilateral supershear rupture velocity (>4 km/s) followed by a slower rupture speed (~3 km/s). Coulomb Failure stress increase imparted by the first event indicates plausible triggering of the doublet aftershock, along with loading of neighboring faults.
  • Extended X-ray Absorption Fine Structure Revealed the Mechanism of Arsenate Removal by the Fe/Mn Oxide-Based Composite under Conditions of Fully Saturated Sorption Sites

    Chubar, Natalia; Szlachta, Małgorzata; Gerda, Vasyl (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2023-09-06) [Article]
    Molecular mechanism of arsenate removal by a promising inorganic composite based on Fe/Mn oxides and MnCO3 was studied under the rarely investigated conditions of fully saturated sorption sites (characteristic of dynamic sorption, such as water treatment plants) at the pH of 4/6/7/8 using As K-edge extended X-ray absorption fine structure (EXAFS)/X-ray absorption near-edge structure (XANES), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). Comparison of arsenic speciation in the initial adsorbate solution (calculated by Visual MINTEQ) and after sorption (determined by As 3d XPS) allowed the interpretation of the initializing forces of the interfacial processes. Contribution of various solid phases of this composite anion exchanger to the removal of arsenate was disclosed by examining the Fe 2p3/2 and Mn 2p3/2 XPS spectra supported by FTIR. As K-edge EXAFS simulation not only proved the chemisorptive binding of aqueous As(V) anions to the Fe/Mn oxide-based adsorbent but also demonstrated the presence of a variety of sorption sites in this complex structured porous material, which became available step-wise upon an increasing pressure on the interface with high arsenate loading during the long-term sorption process. The type of inner-sphere complexation of As(V) on the saturated surface discovered by As K-edge EXAFS modeling was a function of pH. Analysis of EXAFS fitting data resulted in suggestion of a methodological idea on how the EXAFS-derived coordination numbers can be used to distinguish the localization of adsorbed ions (surface versus structure emptiness). This work also provides more insights into the superiority of composite adsorbents (compared to the materials based on individual compounds) in terms of their capability to adapt/change the molecular sorption mechanism in order to inactivate (remove) more toxic aqueous anions.
  • Modulating above-room-temperature magnetism in Ga-implanted Fe5GeTe2 van der Waals magnets

    Yuan, Yanan; Liu, Daxiang; Yu, Jingjing; Zhang, Guanhua; Chen, Xiang; Liu, Ruiqi; Wang, Siyu; Pei, Fangfang; Wei, Long; Li, Zhi; Guo, Junming; Wang, Shouguo; Liao, Zhaoliang; Yan, Wensheng; Qiu, Z. Q.; Yang, M.; Li, Qian (APL Materials, AIP Publishing, 2023-09-01) [Article]
    The creation of van der Waals (vdW) ferromagnets with tunable Curie temperature (TC) and magnetic anisotropy is essential in developing vdW magnet-based devices. Here, we report an effective and reliable method for modulating the magnetic properties of vdW Fe5GeTe2 by site-specific Ga+ implantation. In this study, we report an easy axis in the ab-plane for bulk Fe5GeTe2 (TC = 310 K) and an axis out of the plane for thin Fe5GeTe2 flakes (TC = 290 K). Combining element-resolved photoemission electron microscopy and spatially resolved magneto-optic Kerr microscopy, we find that the implantation of a tiny amount of 10−3 Ga+·Å−3 in Fe5GeTe2 greatly enhances the TC from 290 to 360 K and switches the magnetic easy axis from the out-of-plane c axis to the ab-plane. The room-temperature x-ray magnetic circular dichroism signal is enhanced from 0% to 9% at an implantation level of 10−2 Ga+·Å−3. These results provide new opportunities for tailoring the magnetic properties of vdW materials beyond room temperature.
  • Global Well-Posedness of Displacement Monotone Degenerate Mean Field Games Master Equations

    Bansil, Mohit; Mészáros, Alpár R.; Mou, Chenchen (arXiv, 2023-08-30) [Preprint]
    In this manuscript we construct global in time classical solutions to mean field games master equations in the lack of idiosyncratic noise in the individual agents' dynamics. These include both deterministic models and dynamics driven solely by a Brownian common noise. We consider a general class of non-separable Hamiltonians and final data functions that are supposed to be displacement monotone. Our main results unify and generalize in particular some of the well-posedness results on displacement monotone master equations obtained recently by Gangbo--M\'esz\'aros and Gangbo--M\'esz\'aros--Mou--Zhang.
  • A linear model for inertial modes in a differentially rotating Sun

    Bhattacharya, Jishnu; Hanson, Chris S.; Hanasoge, Shravan M.; Sreenivasan, Katepalli R. (arXiv, 2023-08-24) [Preprint]
    Inertial wave modes in the Sun are of interest owing to their potential to reveal new insight into the solar interior. These predominantly retrograde-propagating modes in the solar subsurface appear to deviate from the thin-shell Rossby-Haurwitz model at high azimuthal orders. We present new measurements of sectoral equatorial inertial modes at m>15 where the modes appear to become progressively less retrograde compared to the canonical Rossby-Haurwitz dispersion relation in a co-rotating frame. We use a spectral eigenvalue solver to compute the spectrum of solar inertial modes in the presence of differential rotation. Focussing specifically on equatorial Rossby modes, we find that the numerically obtained mode frequencies lie along distinct ridges, one of which lies strikingly close to the observed mode frequencies in the Sun. We also find that the n=0 ridge is deflected strongly in the retrograde direction. This suggests that the solar measurements may not correspond to the fundamental n=0 Rossby-Haurwitz solutions as was initially suspected, but to a those for a higher n. The numerically obtained eigenfunctions also appear to sit deep within the convection zone -- unlike those for the n=0 modes -- which differs substantially from solar measurements and complicates inference.
  • Fractional quantum anomalous Hall states in twisted bilayer MoTe2 and WSe2

    Reddy, Aidan P.; Alsallom, Faisal; Zhang, Yang; Devakul, Trithep; Fu, Liang (Physical Review B, American Physical Society (APS), 2023-08-15) [Article]
    We demonstrate via exact diagonalization that AA-stacked transition metal dichalcogenide homobilayers host fractional quantum anomalous Hall (FQAH) states with fractionally quantized Hall conductance at fractional fillings n=13,23 and zero magnetic field. While both states are most robust at angles close to 2-degree, the n=13 state gives way to a charge density wave with increasing twist angle whereas the n=23 state survives across a much broader range of twist angles. We show that the competition between FQAH states and charge density wave or metallic phases is primarily controlled by the wave functions and dispersion of the underlying Chern band, respectively. Additionally, Ising ferromagnetism is found across a broad range of fillings where the system is insulating or metallic alike. The spin gap is enhanced at filling fractions where integer and fractional quantum anomalous Hall states are formed.
  • Valley-dependent tunneling through electrostatically created quantum dots in heterostructures of graphene with hexagonal boron nitride

    Belayadi, A.; Hadadi, N. A.; Vasilopoulos, P.; Abbout, A. (Physical Review B, American Physical Society (APS), 2023-08-14) [Article]
    Kelvin probe force microscopy (KPFM) has been employed to probe charge carriers in a graphene/hexagonal boron nitride (hBN) heterostructure [Nano Lett. 21, 5013 (2021)]. We propose an approach for operating valley filtering based on the KPFM-induced potential U0 instead of using external or induced pseudomagnetic fields in strained graphene. Employing a tight-binding model, we investigate the parameters and rules leading to valley filtering in the presence of a graphene quantum dot (GQD) created by the KPFM tip. This model leads to a resolution of different transport channels in reciprocal space, where the electron transmission probability at each Dirac cone (K1= −K and K2 = +K) is evaluated separately. The results show that U0 and the Fermi energy EF control (or invert) the valley polarization, if electrons are allowed to flow through a given valley. The resulting valley filtering is allowed only if the signs of EF and U0 are the same. If they are different, the valley filtering is destroyed and might occur only at some resonant states affected by U0. Additionally, there are independent valley modes characterizing the conductance oscillations near the vicinity of the resonances, whose strength increases with U0 and are similar to those occurring in resonant tunneling in quantum antidots and to the Fabry-Perot oscillations. Using KPFM, to probe the charge carriers, and graphene-based structures to control valley transport, provides an efficient way for attaining valley filtering without involving external or pseudomagnetic fields as in previous proposals.
  • Mastering lanthanide energy states for next-gen photonic innovation

    Gu, Yuyang; Gu, Chang; Zhang, Yuxiang; Mu, Zhen; Liu, Xiaogang (Science China Chemistry, Springer Science and Business Media LLC, 2023-08-14) [Article]
    Lanthanide-based photonic materials have been extensively explored for use in laser crystals, lighting, fiber-optic communications, bioimaging, diagnostics, and many other fields. In recent years, they have enabled numerous breakthroughs in areas such as single-particle spectroscopy, super-resolution imaging, micro-lasing, lifetime multiplexing, and detection. Here, we summarize recent advances in lanthanide photonic materials from an energy state perspective, focusing on the interplay between energy state manipulation and advanced photonic applications. We then discuss the challenges and prospects for controlling energy states at the single-particle level. We wish to highlight the importance of quantifying and understanding the energy states of lanthanides for future innovations.
  • Improving generalisability and transferability of machine-learning-based maize yield prediction model through domain adaptation

    Priyatikanto, Rhorom; Lu, Yang; Dash, Jadu; Sheffield, Justin (Agricultural and Forest Meteorology, Elsevier BV, 2023-08-09) [Article]
    Modern problems in agricultural management require non-traditional solutions, one of which is by utilizing domain adaptive machine learning models for crop yield prediction which are able to perform reliably in different temporal or spatial domains. However, most studies have focused on the application of domain adaptation to classification tasks such as crop type identification, while the application to regression tasks such as crop yield prediction have been limited. In this study, we explore the generalisability and transferability of ordinary Deep Neural Network (DNN) and domain adaptive neural network models created using three domain adaptation algorithms, namely Discriminative Adversarial Neural Network (DANN), Kullback-Leibler Importance Estimation Procedure (KLIEP), and Regular Transfer Neural Network (RTNN). These three algorithms represent feature-based, instance-based, and parameter-based domain adaptations, respectively. Maize yield records, weather variables, and remotely sensed features from 11 states in the US corn belt acquired in 2006–2020 were compiled and segregated into classes according to temporal (year) and spatial characteristics (annual growing degree days [GDD], vapor pressure deficit [VPD], soil organic content [SOC], and green chlorophyll vegetation index/GCI). We found that models trained using datasets from temperate regions with medium-high GDD and moderate VPD perform well whereas SOC does not significantly affect the generalisability. It is not advisable to train models with datasets constrained by GCI as this feature correlates significantly with the maize yield, and adaptation between two domains that rarely intercept will not work well. We also demonstrate that Kullback-Leibler divergence computed using features from source and target domains can be used to justify the feasibility of domain adaptation. Based on the divergence, a model trained in the US (or another region with sufficient data) is expected to work reliably in other regions through domain adaptation, especially feature-based adaptation.
  • Trace Cu(II)-Mediated Selective Oxidation of Benzothiazole: The Predominance of Sequential Cu(II)–Cu(I)–Cu(III) Valence Transition and Dissolved Oxygen

    Wang, Lihong; Jiang, Ning; Xu, Haodan; Luo, Yiwen; Zhang, Tao (Environmental Science & Technology, American Chemical Society (ACS), 2023-08-08) [Article]
    Trace Cu(II), which inherently exists in soil and some water/wastewater, can trigger persulfate oxidation of some pollutants, but the oxidation capability and mechanism are not well understood, especially toward refractory pollutants. We report in this research that benzothiazole (BTH), a universal refractory pollutant typically originating from tire leachates and various industrial wastewater, can be facilely and selectively removed by peroxydisulfate (PDS) with an equimolar BTH/PDS stoichiometry in the presence of environmental-relevant contents of Cu(II) (below several micromoles). Comprehensive scavenging tests, electron spin resonance analysis, spectroscopy characterization, and electrochemical analysis, revealed that PDS first reduces the BTH-coordinated Cu(II) to Cu(I) and then oxidizes Cu(I) to high-valent Cu(III), which accounts for the BTH degradation. Moreover, once the reaction is initiated, the superoxide radical is probably produced in the presence of dissolved oxygen, which subsequently dominates the reduction of Cu(II) to Cu(I). This facile oxidation process is also effective in removing a series of BTH derivatives (BTHs) that are of environmental concern, thus can be used for their source control. The results highlight the sequential Cu(II)-Cu(I)-Cu(III) transition during PDS activation and the crucial role of contaminant coordination with Cu(II) in oxidative transformation.
  • Adsorption-Induced Deformation of Zeolites 4A and 13X: Experimental and Molecular Simulation Study

    Emelianova, Alina; Balzer, Christian; Reichenauer, Gudrun; Gor, Gennady Y. (Langmuir, American Chemical Society (ACS), 2023-08-04) [Article]
    Gas adsorption in zeolites leads to adsorption-induced deformation, which can significantly affect the adsorption and diffusive properties of the system. In this study, we conducted both experimental investigations and molecular simulations to understand the deformation of zeolites 13X and 4A during carbon dioxide adsorption at 273 K. To measure the sample’s adsorption isotherm and strain simultaneously, we used a commercial sorption instrument with a custom-made sample holder equipped with a dilatometer. Our experimental data showed that while the zeolites 13X and 4A exhibited similar adsorption isotherms, their strain isotherms differed significantly. To gain more insight into the adsorption process and adsorption-induced deformation of these zeolites, we employed coupled Monte Carlo and molecular dynamics simulations with atomistically detailed models of the frameworks. Our modeling results were consistent with the experimental data and helped us identify the reasons behind the different deformation behaviors of the considered structures. Our study also revealed the sensitivity of the strain isotherm of zeolites to pore size and other structural and energetic features, suggesting that measuring adsorption-induced deformation could serve as a complementary method for material characterization and provide guidelines for related technical applications.
  • Dynamic Rupture Process of the 2023 Mw 7.8 Kahramanmaraş Earthquake (SE Türkiye): Variable Rupture Speed and Implications for Seismic Hazard

    Wang, Zijia; Zhang, Wenqiang; Taymaz, Tuncay; He, Zhongqiu; Xu, Tianhong; Zhang, Zhenguo (Geophysical Research Letters, American Geophysical Union (AGU), 2023-08-03) [Article]
    We considered various non-uniformities such as branch faults, rotation of stress field directions, and changes in tectonic environments to simulate the dynamic rupture process of the 6 February 2023 Mw 7.8 Kahramanmaraş earthquake in SE Türkiye. We utilized near-fault waveform data, GNSS static displacements, and surface rupture to constrain the dynamic model. The results indicate that the high initial stress accumulated in the Kahramanmaraş-Çelikhan seismic gap leads to the successful triggering of the East Anatolian Fault (EAF) and the supershear rupture in the northeast segment. Due to the complexity of fault geometry, the rupture speed along the southeastern segment of the EAF varied repeatedly between supershear and subshear, which contributed to the unexpectedly strong ground motion. Furthermore, the triggering of the EAF reminds us to be aware of the risk of seismic gaps on major faults being triggered by secondary faults, which is crucial to prevent significant disasters.
  • Integrating of electrocoagulation process with submerged membrane bioreactor for wastewater treatment under low voltage gradients

    Bani-Melhem, Khalid; Elektorowicz, Maria; Tawalbeh, Muhammad; Al Bsoul, Abeer; El Gendy, Ahmed; Kamyab, Hesam; Yusuf, Mohammad (Chemosphere, Elsevier BV, 2023-08-01) [Article]
    Polycyclic aromatic hydrocarbons (PAHs) are present in wastewater from various sources like industry, roads, and household waste. They are difficult to remove due to their low concentration, stability, and ability to combine with other organic substances. The study aimed to address membrane fouling in the submerged membrane bioreactor (SMBR) used for wastewater treatment. An aluminum electrocoagulation (EC) device was combined with SMBR as a pre-treatment to reduce fouling. The EC-SMBR process was compared with a conventional SMBR without EC, both fed with real grey water. Lower voltage gradients were used to prevent biological growth. The comparison was conducted over 60 days with constant transmembrane pressure and infinite solid retention time (SRT). In phase I, when the EC device was operated at a low level of voltage gradient (0.64 V/cm), no significant improvement in the pollutants removal was observed in terms of color, turbidity, and chemical oxygen demand (COD). Nevertheless, during phase II, a voltage gradient of 1.26 V/cm achieved up to 100%, 99.7%, 92%, 94.1%, and 96.5% removals in the EC-SMBR process in comparison with 95.1%, 95.4%, 85%, 91.7% and 74.2% removals in the SMBR process for turbidity, color, COD, ammonia nitrogen (NH3–N), total phosphorus (TP), respectively. SMBR showed better anionic surfactant (AS) removal than EC-SMBR. A voltage gradient of 0.64 V/cm in the EC unit significantly reduced fouling by 23.7%, while 1.26 V/cm showed inconsistent results. Accumulation of Al ions negatively affected membrane performance. Low voltage gradients in EC can control SMBR fouling if Al concentration is controlled. Future research should investigate EC-SMBR with constant membrane flux for large-scale applications, considering energy consumption and operating costs.
  • A Novel 3D Beam Domain Channel Model for UAV Massive MIMO Communications

    Chang, Hengtai; Wang, Cheng Xiang; Bian, Ji; Feng, Rui; He, Yubei; Chen, Yunfei; Aggoune, El Hadi M. (IEEE Transactions on Wireless Communications, Institute of Electrical and Electronics Engineers (IEEE), 2023-08) [Article]
    Due to the agile maneuverability, unmanned aerial vehicles (UAVs) have shown great promise for on-demand communications in the next-generation wireless networks. Considering the massive multiple-input multiple-output (MIMO) configuration, this paper proposes a novel three-dimensional (3D) beam domain channel model (BDCM) for UAV communications. Through dividing the large antenna array into several sub-arrays and classifying multipath components as near-field and far-field components, the proposed BDCM takes the spherical wave front (SWF) and array non-stationarity into account. Channel statistical properties including spatial-temporal-frequency correlation function (STF-CF), root-mean-squared (RMS) Doppler spread, beam spread, channel matrix collinearity (CMC), and stationary time interval are derived and simulated for the proposed BDCM. Influences of SFW and non-stationary properties on the statistical properties and system performance are analyzed. Simulation results show that, compared with the equivalent geometry-based stochastic model (GBSM), the proposed BDCM has better temporal correlation, while BDCM and GBSM are equivalent in the system performance evaluation. Furthermore, the performance of the proposed BDCM is evaluated in terms of accuracy, complexity, and pervasiveness. The results show that the proposed BDCM can represent massive MIMO channel properties accurately with low complexity and good compatibility.
  • Immiscible imbibition in fractured media: A dual-porosity microfluidics study

    Cardona, Alejandro; Santamarina, Carlos (International Journal of Rock Mechanics and Mining Sciences, Elsevier BV, 2023-07-30) [Article]
    We use dual porosity microfluidics and fluorescence microscopy to investigate immiscible imbibition in the pore networks formed in fractured rocks, and to identify emergent pore-scale events that arise as a result of the interplay between advection-dominant flow in fractures (F) and capillary-driven matrix imbibition (M). The dimensionless ratio between the two time scales T = tF/tM defines the various displacement patterns: fracture-dominant advective invasion at low Τ-values leaves a higher residual non-wetting phase saturation; compact invasion is observed at intermediate T-values, and fractures act as capillary barriers during matrix-dominant capillary imbibition at high Τ-values. Experiments and analyses show effective capillary-driven corner flow during immiscible imbibition; in particular, corner flow imbibition displaces non-wetting fluids that were initially trapped in the matrix during fast advective invasion. In contrast to wetting fluid invasion and imbibition, injected non-wetting fluids invade and flow along fractures as soon as the capillary pressure reaches the fracture entry pressure, and there is no matrix invasion and drainage. The capillary pressure versus saturation curve for the fractured rock mass assumes that fractures and matrix blocks share the same capillary pressure at equilibrium; then, the combined pressure-saturation response is a function of their relative contributions to the total porosity. In the absence of gouge or precipitates, fractures determine the entry pressure while the matrix controls storativity.
  • Tailoring Graphene Functionalization with Organic Residues for Selective Sensing of Nitrogenated Compounds: Structure and Transport Properties via QM Simulations

    Baachaoui, Sabrine; Sementa, Luca; Hajlaoui, Rabiaa; Aldulaijan, Sarah; Fortunelli, Alessandro; Dhouib, Adnene; Raouafi, Noureddine (The Journal of Physical Chemistry C, American Chemical Society (ACS), 2023-07-29) [Article]
    Graphene bearing organic functional groups chemically tethered to its surface via covalent bonds can find several applications in the sensing of gas, heavy metal ions, and other target species of interest. Herein, we used DFT simulations to study the thermodynamics of graphene functionalization with substituted carbenes, and the use of the resulting adducts to detect gaseous nitrogenated compounds─focusing on ammonia (NH3), methylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA). We find that the modified materials can interact with the amines, selectively also in the presence of other gases such as CO2, SO2, H2S, and CH4. Changes in the electronic properties of the system upon adsorption such as charge density, Löwdin partial charges, and projected density of states (PDOS) were used to analyze the interaction. Expected recovery times suggest that these nanomaterials can be used to detect the nitrogenated compounds here investigated at relatively low temperatures (298 and 373 K). Furthermore, by modeling the conductance of the functionalized graphene bare and in the presence of ammonia, we show that quantum conductance and the integrated currents are sensitive to functionalization and, importantly, to the presence of ammonia under determined conditions, which in principle allows tuning the sensitivity of the resulting device. Our work thus clarifies the principles governing this phenomenon. Carbene-functionalized graphene is concluded to be a potentially good candidate to replace noble-metal-modified graphene for the detection of ammonia/amines in chemoresistance or field-effect transistor-based sensors.
  • Recent Progress in Printed Photonic Devices: A Brief Review of Materials, Devices, and Applications

    AlAmri, Amal (Polymers, MDPI AG, 2023-07-29) [Article]
    Printing electronics incorporates several significant technologies, such as semiconductor devices produced by various printing techniques on flexible substrates. With the growing interest in printed electronic devices, new technologies have been developed to make novel devices with inexpensive and large-area printing techniques. This review article focuses on the most recent developments in printed photonic devices. Photonics and optoelectronic systems may now be built utilizing materials with specific optical properties and 3D designs achieved through additive printing. Optical and architected materials that can be printed in their entirety are among the most promising future research topics, as are platforms for multi-material processing and printing technologies that can print enormous volumes at a high resolution while also maintaining a high throughput. Significant advances in innovative printable materials create new opportunities for functional devices to act efficiently, such as wearable sensors, integrated optoelectronics, and consumer electronics. This article provides an overview of printable materials, printing methods, and the uses of printed electronic devices.

View more