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•Functionalization of graphene oxide (GO) by amino acids (AA) was performed.•Formation of a GO liquid crystalline (LC) phase was shown.•pH-dependent behavior of AA-functionalized ...GOLCs was demonstrated.•L-cysteine dimerization occurred on the GO platform.
The colloidal 2D materials based on graphene and its modifications are of great interest when it comes to forming LC phases. These LC phases allow controlling the orientational order of colloidal particles, paving the way for the efficient processing of modified graphene with anisotropic properties. Here, we present the peculiarities of AA functionalization of GO, along with the formation of its LC phase and orientational behavior in an external magnetic field. We discuss the influence of pH on the GOLC, ultimately showing its pH-dependent behavior for GO-AA complexes. In addition, we observe different GO morphology changes due to the presence of AA functional groups, namely L-cysteine dimerization on the GO platform. The pH dependency of AA-functionalized LC phase of GO is examined for the first time. We believe that our studies will open new possibilities for applications in bionanotechnologies due to self‐assembling properties of LCs and magnificent properties of GO.
•Hydrothermally synthesized MoS2/rGO hybrid nanocomposites were obtained.•Incorporation of 5CB increases the sensitivity and charge storage efficiency of MoS2/rGO.•Responsivity, detectivity, ...photocurrent rise and decay times for MoS2/rGO both with and without the presence of 5CB are estimated.•Photocurrent switching effect was observed in case of incorporating 5CB to MoS2/rGO hybrid nanocomposites.
Hybrid systems of two-dimensional (2D) materials (such as graphene-family materials and 2D transition metal dichalcogenides) are attracting much attention due to their distinctive optoelectronic, thermal, mechanical, and chemical properties. The application perspectives of these materials in various fields further expand when enriching those with liquid crystals (LCs) primarily due to their enhanced tunability and functionality. In this study, we report on the hydrothermal synthesis of hybrid nanocomposites composed of MoS2 and rGO and discuss tuning possibilities of their electro-optical properties by incorporating thermotropic LCs. In particular, we demonstrate that the incorporation of 5CB LC increases the sensitivity and charge storage efficiency of the hybrid nanocomposites. In addition, we also present the responsivity, detectivity, and response time properties of the hybrid nanocomposites of MoS2/rGO, both with and without the inclusion of nematic LCs. Furthermore, we demonstrate that the system exhibits a 5CB-induced photocurrent switching effect. We believe the findings will open new doors for applications of these materials in optoelectronics and photonics.
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Resonant tunneling through defect levels in the
h
-BN barrier of van-der-Waals heterostructures is investigated. The effect of multiplication of the tunneling resonances through these levels due to ...the effect of a high degree of imperfection of the structure of the neighboring graphene layer formed intentionally by its processing in plasma is found. Various mechanisms of such an effect are discussed.
Van der Waals (vdW) heterostructures are stacks of two-dimensional (2D) materials that can exhibit novel physical phenomena and open a door to new device applications. A common method to create such ...heterostructures is the dry transfer of mechanically cleaved 2D layers, which are usually small in size and limited in material diversity. Here, we propose a simple and clean dry assembly method using polydimethylsiloxane (PDMS) to construct heterostructures based on both mechanically exfoliated and chemically vapor deposited (CVD) 2D materials. This technique allows us to combine the advantages of both types of materials, such as large size, high quality, and a wide range of properties. We demonstrate the feasibility and versatility of our method by fabricating various heterostructures with different combinations of CVD and exfoliated 2D materials, such as graphene, hexagonal boron nitride, molybdenum disulfide, and tungsten diselenide. Our method opens new possibilities for exploring the physics and applications of van der Waals heterostructures.
In this work, we study phonon and electronic properties of graphene on SiO2/Si and Al2O3 by simultaneous Raman and electrical measurements in the temperature range from room temperature to 550 °C, or ...at voltages from 20 to −20 V. The dependencies of G and 2D peak parameters and electrical resistance on temperature and voltage made it possible to observe in situ a competition between the p-type adsorbate removal from graphene surface and substrate-induced doping due to graphene-substrate conformality increase, both stimulated by either ambient or Joule heating. The analyzed parameters were dominated by the conformality increase, with the hole density increasing significantly and unidirectionally, while resistance and I-V curves fluctuated due to the competition. Having calculated Raman peak shift temperature coefficients, resistance temperature coefficients, total variations of carrier density, resistance and strain, we show that Al2O3 substrate can be used to reduce the desorption barrier, the overall doping, the impact on graphene resistance and on phonon anharmonicity – however, it should be used with regard to the possibility of introducing strain or stronger doping after longer treatments. The conformality effects should be taken into account when performing annealing, as well as graphene applications for sensors or strong electric currents.
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•Ambient and Joule heating change graphene from quasi-suspended state to supported one.•Resistance and I-V curves show competition between conformation and desorption.•Hole density is dominated by graphene-substrate conformality increase.•Al2O3 affects graphene less before temperature and current treatments.•SiO2/Si affects graphene less after temperature and current treatments.
The evolution of dynamic processes in graphene-family materials are of great interest for both scientific purposes and technical applications. Scanning electron microscopy and transmission electron ...microscopy outstand among the techniques that allow both observing and controlling such dynamic processes in real time. On the other hand, functionalized graphene oxide emerges as a favorable candidate from graphene-family materials for such an investigation due to its distinctive properties, that encompass a large surface area, robust thermal stability, and noteworthy electrical and mechanical properties after its reduction. Here, we report on studies of surface structure and adsorption dynamics of L-Cysteine on electrochemically exfoliated graphene oxide's basal plane. We show that electron beam irradiation prompts an amorphization of functionalized graphene oxide along with the formation of micropatterns of controlled geometry composed of L-Cysteine-Graphene oxide nanostructures. The controlled growth and predetermined arrangement of micropatterns as well as controlled structure disorder induced by e beam amorphization, in its turn potentially offering tailored properties and functionalities paving the way for potential applications in nanotechnology, sensor development, and surface engineering. Our findings demonstrate that graphene oxide can cover L-Cysteine in such a way to provide a control on the positioning of emerging microstructures about 10–20 μm in diameter. Besides, Raman and SAED measurement analyses yield above 50% amorphization in a material. The results of our studies demonstrate that such a technique enables the direct creation of micropatterns of L-Cysteine-Graphene oxide eliminating the need for complicated mask patterning procedures.
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•Functionalization of electrochemically exfoliated graphene oxide (GO) by L-Cysteine (Cys) was performed.•SEM and STEM techniques allowing precise control over micrometer-scale positioning of Cys-GO nanocomposites were suggested.•Amorphization of Cys-GO nanocomposites boosted by the e-beam irradiation was demonstrated.•Direct creation of micropatterns of Cys-GO eliminating the need for complicated mask patterning procedures.
It is well-known that superconductivity in thin films is generally suppressed with decreasing thickness. This suppression is normally governed by either disorder-induced localization of Cooper pairs, ...weakening of Coulomb screening, or generation and unbinding of vortex–antivortex pairs as described by the Berezinskii–Kosterlitz–Thouless (BKT) theory. Defying general expectations, few-layer NbSe2, an archetypal example of ultrathin superconductors, has been found to remain superconducting down to monolayer thickness. Here, we report measurements of both the superconducting energy gap Δ and critical temperature T C in high-quality monocrystals of few-layer NbSe2, using planar-junction tunneling spectroscopy and lateral transport. We observe a fully developed gap that rapidly reduces for devices with the number of layers N ≤ 5, as does their T C. We show that the observed reduction cannot be explained by disorder, and the BKT mechanism is also excluded by measuring its transition temperature that for all N remains very close to T C. We attribute the observed behavior to changes in the electronic band structure predicted for mono- and bi- layer NbSe2 combined with inevitable suppression of the Cooper pair density at the superconductor-vacuum interface. Our experimental results for N > 2 are in good agreement with the dependences of Δ and T C expected in the latter case while the effect of band-structure reconstruction is evidenced by a stronger suppression of Δ and the disappearance of its anisotropy for N = 2. The spatial scale involved in the surface suppression of the density of states is only a few angstroms but cannot be ignored for atomically thin superconductors.
The morphological plasticity of plant roots is a key factor in their ability to tolerate a wide range of edaphic stresses. There are many unanswered questions relating to nanotechnology and its ...potential uses for sustainable agriculture. The main purpose of this study was to examine the effects of salinity-induced morphogenic responses and zinc oxide nanoparticles (ZnO-NPs) on root characteristics, growth, MDA content, antioxidant enzymatic activity, and root ion accumulation in rice (Oryza sativa L.). The experiment was conducted in a hydroponic culture containing 50 mg/L of ZnO-NPs and different concentrations (60, 80, and 100 mM) of NaCl for 14 days. The results indicated a decrease in rice root growth due to exposure to salinity (length, fresh, and root dry weight). The results showed that salinity caused a reduction in rice root growth (length, fresh, and root dry weight). Higher root sodium (Na+) accumulation, MDA content, and potassium level decreased with increasing salinity. Root length, root fresh weight, root dry weight, root K+ content, and root antioxidant enzymatic activity were all enhanced by applying 50 mg/L ZnO-NPs often in salinity. SEM analysis revealed that ZnO-NPs treatments significantly improved root morphology. There was a notable decrease in root Na+ content as a result, which improved the K+/Na+ ratio in the rice’s root system. These findings suggest that O. sativa, when treated with ZnO-NPs, can thrive under salt-stress conditions, opening up the possibility of cultivating the plant in extreme climates.
Salinized land is slowly spreading across the world. Reduced crop yields and quality due to salt stress threaten the ability to feed a growing population. We discussed the mechanisms behind ...nano-enabled antioxidant enzyme-mediated plant tolerance, such as maintaining reactive oxygen species (ROS) homeostasis, enhancing the capacity of plants to retain K+ and eliminate Na+, increasing the production of nitric oxide, involving signaling pathways, and lowering lipoxygenase activities to lessen oxidative damage to membranes. Frequently used techniques were highlighted like protecting cells from oxidative stress and keeping balance in ionic state. Salt tolerance in plants enabled by nanotechnology is also discussed, along with the potential role of physiobiochemical and molecular mechanisms. As a whole, the goal of this review is meant to aid researchers in fields as diverse as plant science and nanoscience in better-comprehending potential with novel solutions to addressing salinity issues for sustainable agriculture.
Bacteriophages are the most abundant members of the microbiota and have the potential to shape gut bacterial communities. Changes to bacteriophage composition are associated with disease, but how ...phages impact mammalian health remains unclear. We noted an induction of host immunity when experimentally treating bacterially driven cancer, leading us to test whether bacteriophages alter immune responses. Treating germ-free mice with bacteriophages leads to immune cell expansion in the gut. Lactobacillus, Escherichia, and Bacteroides bacteriophages and phage DNA stimulated IFN-γ via the nucleotide-sensing receptor TLR9. The resultant immune responses were both phage and bacteria specific. Additionally, increasing bacteriophage levels exacerbated colitis via TLR9 and IFN-γ. Similarly, ulcerative colitis (UC) patients responsive to fecal microbiota transplantation (FMT) have reduced phages compared to non-responders, and mucosal IFN-γ positively correlates with bacteriophage levels. Bacteriophages from active UC patients induced more IFN-γ compared to healthy individuals. Collectively, these results indicate that bacteriophages can alter mucosal immunity to impact mammalian health.
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•Bacteriophages target specific bacteria and mitigate bacterially driven colon cancer•Phages activate phage-specific and non-specific IFN-γ mediated immune responses via TLR9•Phages exacerbate colitis, and TLR9/IFNγ blockade abrogates phage-mediated inflammation•UC patient responses to fecal microbiota therapy correlate with Caurovirales abundance
Bacteriophages are abundant components of the gut microbiota, but how they impact health and immunity is unknown. Gogokhia et al. report that bacteriophages activate IFN-γ through a TLR9-dependent pathway and exacerbate colitis. Supporting this, increased abundance of bacteriophages in patients with ulcerative colitis correlates with mucosal IFN-γ responses.
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