Presence Of GR Research Articles

The glucocorticoid receptor potentiates aldosterone-induced transcription by the mineralocorticoid receptor

The glucocorticoid and mineralocorticoid receptors (GR and MR, respectively) have distinct, yet overlapping physiological and pathophysiological functions. There are indications that both receptors interact functionally and physically, but the precise role of this interdependence is poorly understood. Here, we analyzed the impact of GR coexpression on MR genome-wide transcriptional responses and chromatin binding upon activation by aldosterone and glucocorticoids, both physiological ligands of this receptor. Transcriptional responses of MR in the absence of GR result in fewer regulated genes. In contrast, coexpression of GR potentiates MR-mediated transcription, particularly in response to aldosterone, both in cell lines and in the more physiologically relevant model of mouse colon organoids. MR chromatin binding is altered by GR coexpression in a locus- and ligand-specific way. Single-molecule tracking of MR suggests that the presence of GR contributes to productive binding of MR/aldosterone complexes to chromatin. Together, our data indicate that coexpression of GR potentiates aldosterone-mediated MR transcriptional activity, even in the absence of glucocorticoids.

Micromechanical response of graphene coating on nt-TiAl under nanoindentation

The nanoindentation response of graphene (Gr) coating on nanotwin titanium-aluminum (nt-TiAl) matrix composites was studied using molecular dynamics (MD) simulation. The indentation velocity, twin boundary spacing, and parallel and vertical Z-axes are studied. The results show that the bearing capacity and hardness of Gr coating is significantly higher than that after coating failure, and the load-displacement curve shows the same phenomenon. Damage to the substrate material at varying speeds is indicated by atomic aggregation near the Gr coating, with the center of aggregation showing a negative correlation with indentation velocity. The matrix's damaged area is larger when the twin layer is perpendicular to the Z-axis and deeper when parallel, showing that the twin structure limits material damage by hindering dislocation expansion. Moreover, the presence of Gr coating delayed the matrix's plastic deformation process. This delay effect significantly improves the mechanical properties of composites, which have potential applications in aerospace.

Photoluminescence patterns via single-layer exfoliation in Gr/MoS2 heterostructure using contact-mode atomic force microscopy

The stacking of two-dimensional (2D) materials presents numerous opportunities for various nanodevice applications. Achieving atomic-thick precision in microscopic patterning is crucial to manipulating the functionalities and interfacial interactions of the 2D heterostructures. In this study, a silicon atomic force microscopy (AFM) tip was utilized to rub the surface of graphene (Gr)/MoS2 heterostructure and manipulate its physical properties. The contact force between the AFM tip and Gr/MoS2 surface was adjusted between 110 and 660 nN. Before rubbing, the photoluminescence (PL) intensity of MoS2 was quenched due to the presence of Gr. After rubbing, the optical image and Raman spectroscopy acquired from the Gr/MoS2 heterostructure indicated that Gr started to be exfoliated by a contact force exceeding 220 nN. The absence of Gr due to exfoliation led to the restoration of MoS2′s pristine PL intensity. For demonstration, the AFM tip was used to exfoliate a designed micro-area covered with Gr using a 660 nN force, forming a patterned PL of MoS2. This technique enabled the creation of different structures to develop unique multilayer 2D material devices.

FRI164 The Glucocorticoid Receptor is Required for Efficient Aldosterone-induced Transcription by the Mineralocorticoid Receptor

Abstract Disclosure: T.A. Johnson: None. G. Fettweis: None. K. Wagh: None. B. Almeida-Prieto: None. G.L. Hager: None. D. Alvarez de la Rosa: None. The glucocorticoid and mineralocorticoid receptors (GR and MR, respectively) have distinct, yet overlapping physiological and pathophysiological functions. There is evidence in the literature that the two receptors interact both functionally and physically, but the global role of this interdependence is poorly understood (1,2). Here, we analyze the impact of GR co-expression on MR genome-wide chromatin binding and transcriptional responses to aldosterone and glucocorticoids. Our data show that GR co-expression alters MR genome-wide binding in locus- and ligand-specific ways. MR binding to consensus hormone response elements is affected by GR. Additionally, gene responses by MR in the absence of GR are weak and show poor correlation with chromatin binding. In contrast, co-expression of GR greatly potentiates genome-wide MR-mediated transcription, particularly in response to aldosterone. These aldosterone-mediated transcriptional responses do not occur with GR alone. Finally, single molecule tracking of MR in live cells indicates that the presence of GR contributes to productive chromatin binding events. Together, our data indicate that co-expression of GR enables optimal aldosterone-mediated MR transcriptional activity, even in the absence of glucocorticoids. REFERENCES: (1) Mayumi Nishi et al., J Neuroscience. 2004 May 26; 24(21):4918 - 4927. (2) Liu et al., PNAS. Dec 1995; 92: 12480-12484. Presentation Date: Friday, June 16, 2023

Graphene nanoplatelets reinforced Al-Cu-Mg composite fabricated using laser powder bed fusion: microstructure, mechanical properties, and wear behaviour

Aluminium-based metal matrix composites reinforced with graphene (Gr) and its derivatives have been reported as promising composites due to their superior properties such as strength, damage tolerance, fatigue resistance, and density. However, the crack and porosity susceptibility of Aluminium 2024 Alloy (AA2024) with added Gr when fabricated using additive manufacturing techniques is not sufficiently well understood. The present work addresses this knowledge gap by focusing on the effect of graphene nanoplatelets (GNPs) and scanning speed on the AA2024 composites’ wear performance and microstructural and mechanical properties of specimens fabricated using laser powder bed fusion (LPBF). The experimental findings demonstrate that up to 0.5% presence of Gr in the composite improves its crystallite size and microhardness by up to 37.6% and 45%, respectively; however, it increases the porosity and crack formation due to the high laser power requirement. Moreover, the composites’ macroscale scratch and nanoscale wear performances showed improvements by up to 50% and 56% with higher Gr concentration (0.5%), suggesting that Gr is distributed uniformly in the structure. The improved understanding of the relationship between microstructure and mechanical characteristics of the GNPs/Al2024 composites fabricated using LPBF in terms of cracking and porosity formation is another significant contribution of this work.Graphical abstract

Revealing the toughening mechanisms in graphene/tungsten nanocomposites with hierarchical nacre-like structures

The integration of traditional “brick-and-mortar” structure with graphene additives demonstrates remarkable efficiency for enhancing the toughness of metal matrix composites. This study proposes five different types of graphene/tungsten (Gr/W) nanocomposites that incorporate hierarchical nacre-like structures, leveraging the tensile toughness benefits of both nacre and graphene in metal matrix composites. To evaluate the mechanical properties and microstructure evolution process of Gr/W nanocomposites, series of atomistic simulations are carried out. It is found that Gr/W nanocomposites with hierarchical nacre-like structures possess superior tensile toughness compared to pure W, albeit at the cost of partial strength reduction. The presence of Gr “mortars” between W “bricks” is crucial in improving toughness through shear deformation accommodation. A larger volume percentage of Gr “mortars” will promote the tensile toughness increment of Gr/W nanocomposites. In contrast to pure W, the Gr/W samples exhibit no twin boundary migration, as the shear strain in W bricks is negligible. And the tensile toughness of Gr/W nanocomposites exhibits a negative correlation with temperature. Specifically, with the temperature increases from 300 to 1500 K, the toughness decreases from 0.971 to 0.304 GJ/m3. The proposed hierarchical nacre-like structures could provide valuable insights for the design of other metal matrix composites with robust performances.

A facile and eco-friendly hydrothermal synthesis of magnetic graphite nanocomposite and its application in water purification

In this research, a magnetic graphite nanocomposite (MGN) was synthesized by an easy and efficient hydrothermal process from magnetite nanoparticles (NP-SYN) and graphite nanoplatelets (GR). MGN was characterized by X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), N2 adsorption and desorption analysis, X-ray photoelectron spectroscopy (XPS), and point of zero charge (pHpzc) analysis. The thickness for GR was found to be 34 nm, and crystallite sizes for NP-SYN and MGN were around 37 and 48 nm, respectively. MGN shows the presence of GR and iron oxides from the NP-SYN. The surface areas for GR, NP-SYN, and MGN were around 191, 18, and 121 m2 g−1, respectively. The pHpzc results for GR, NP-SYN, and MGN ranged from 6 to 7. The NP-SYN, GR, and MGN were used as adsorbents to remove reactive black 5 (RB5) dye from aqueous solution. This method’s batch removal process was designed based on a central composite rotational design (CCRD). The efficiency of RB5 uptake for all adsorbents was obtained from the quadratic model under optimum conditions of prominent parameters by desirability function (mass of adsorbent 6.6 mg, dye concentration 85.1 mg L−1, and agitation speed 902.7 rpm). Under these conditions, the adsorption capacity values were 10.16, 92.08, and 28.83 mg g−1 for NP-SYN, GR, and MGN, respectively, indicating that the adsorption power of the nanoparticle increased after incorporating GR, maintaining its magnetic properties. Therefore, the proposed adsorbents in this work have potential for removing RB5 dye from water solutions.

Quadratic convection on the radiative flow of ternary nanofluid Gr–Ag–TiO2–H2O subjected to velocity slip and temperature jump

This paper deals with the analysis of the flow and heat transfer performance of ternary nanofluid flowing past a stretching sheet under the influence of quadratic convection. The ternary nanofluid is formed by suspending three different nanoparticles, namely, titanium dioxide (TiO2), silver (Ag) and graphene (Gr) in the base fluid water (H2O). Thus, the ternary nanofluid obtained is Gr–Ag–TiO2/H2O where the hybrid nanofluid Ag–TiO2/H2O forms the base fluid for the resulting ternary nanofluid. The addition of TiO2 nanoparticles enhances the photocatalytic nature of the base fluid and makes it useful in various applications concerning the medicinal field. The presence of Gr helps in intensifying the thermal conductivity of water while the suspension of silver nanoparticles ensures chemical stability. Meanwhile, the thermophysical properties of the ternary nanofluid are mathematically defined and the system of equations that describe the flow of a ternary nanofluid past a stretching sheet is framed using differential equations. The outcomes of this study are interpreted through graphs for velocity and temperature profiles of the ternary nanofluid. It was mainly observed that the thermal conductance of ternary nanofluid was higher than the monophase and hybrid nanofluid. Also, the presence of quadratic convection had a prominent impact on the ternary nanofluid flow. The Nusselt number was found to be greater for spherical nanoparticles and it was found to be least for blade-shaped nanoparticles.

Tribological study of aluminium-B4C/Gr composite-An experimental study

Being one of the lightweight material and easily available materials aluminium has a lot of applications in various fields of automobile, electronics, and aircraft. In this study, the tribological study of aluminium-based composite is being done for the wear characteristics. A comparison is being made for the wear study of the Al 6063-based composite with the base alloy. Stir casting is used to form the composite. Microscopic images confirm the presence of Boron Carbide (B4C) and Graphite (Gr.) particles in the composite. Tribological experiments are being performed to check for the outcome of B4C and Gr.reinforcementparticles on the composite wear rate and SEM images of the worn surfaces depict that the insite presence of Gr. particles reduces the wear characteristics and improves the surface quality forthe worn composite as compared to the base alloy.

Effects of an epitaxial graphene layer for the growth of nickel silicides on a Ni(111) substrate

In this paper, we report on an in-depth study on the growth of nickel silicides, either on a clean Ni(111) substrate or in the presence of a previously-grown epitaxial single graphene (Gr) layer, by means of Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM). We demonstrate that two different nickel silicides, namely Ni3Si and Ni2Si, progressively form as the annealing temperature is increased from 450 °C to 600 °C. The presence of the Gr layer does not change the nature of the two silicide phases but rather affects the morphology of the silicide overlayer. Indeed, in the presence of Gr, the deposited silicon atoms intercalate by passing through the Gr defects or domain boundaries and accumulate on specific sample areas, resulting in the formation of multilayer silicide islands. In the absence of Gr, the deposited silicon atoms react uniformly with the nickel substrate, resulting in the formation of homogeneous large scale silicide layers.

Electrochemical sensor based on metal-free materials composed of graphene and graphene oxide for sensitive detection of cadmium ions in water

In this work, a high-speed dispersive homogenizer as an exfoliating device, and graphite oxide was used to prepare graphene and graphene oxide metal-free composite materials (GR/GO composites) for electrochemical detection of cadmium ions (Cd2+) present in water. Glassy carbon electrode was modified with GR/GO composite by placing a suspension of the composite on the electrode and evaporating the solvent. The fabricated GR/GO composite had a sheet-like structure in which the presence of GO enhanced the hydrophilicity, whereas the presence of GR improved the conductivity. The higher hydrophilicity in a wide pH range of the composite electrode made it favorable to have better contacts with Cd2+ and the good conductivity; these enhanced the response of electrochemical signals. As a result, the assembled electrochemical Cd2+ sensor with GR/GO composite electrode exhibited superior analysis performances than those with GR and GO respectively, which exhibited wide linear range (0–10 μM), low value of detection limit (0.087 μM), reliable stability and selectivity. Moreover, the sensor based on GR/GO composites showed satisfactory detection accuracy for tap water samples, suggesting that the GR/GO composites are promising materials for electrochemical heavy metal ion sensors.

Engineering the spin conversion in graphene monolayer epitaxial structures

Spin Hall and Rashba–Edelstein effects, which are spin-to-charge conversion phenomena due to spin–orbit coupling (SOC), are attracting increasing interest as pathways to manage rapidly and at low consumption cost the storage and processing of a large amount of data in spintronic devices as well as more efficient energy harvesting by spin-caloritronics devices. Materials with large SOC, such as heavy metals (HMs), are traditionally employed to get large spin-to-charge conversion. More recently, the use of graphene (gr) in proximity with large SOC layers has been proposed as an efficient and tunable spin transport channel. Here, we explore the role of a graphene monolayer between Co and a HM and its interfacial spin transport properties by means of thermo-spin measurements. The gr/HM (Pt and Ta) stacks have been prepared on epitaxial Ir(111)/Co(111) structures grown on sapphire crystals, in which the spin detector (i.e., top HM) and the spin injector (i.e., Co) are all grown in situ under controlled conditions and present clean and sharp interfaces. We find that a gr monolayer retains the spin current injected into the HM from the bottom Co layer. This has been observed by detecting a net reduction in the sum of the spin Seebeck and interfacial contributions due to the presence of gr and independent from the spin Hall angle sign of the HM used.

The effect of graphene and reduced graphene oxide on the resistive switching behavior of La0.7Ba0.3MnO3

Future developments in the non-volatile memory design like resistive random access memory (RRAM) holds the backbone of data-controlled applications. The present study reports the investigation of the resistive switching behaviour of a novel nanocomposite system composed of La0.7Ba0.3MnO3 and Graphene (Gr)/reduced graphene oxide (rGO) for memory design. The presence of Gr offers a superior switching behaviour, the microscopic origin of which lies in the formation/breakage of conduction filamentary paths, formed through the presence of oxygen vacancies as supported via X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) measurements. The change in the resistance states can be accounted for the exchange interaction along the Mn3+–O2−–Mn4+ chain, offering simultaneous control over the resistance states via the electric and magnetic field. The conduction behaviour is dominated by the Fowler-Nordheim tunnelling mechanism. The presence of robust and stable switching behaviour over 1000 cycles, stable ON/OFF ratio, and simple synthesis process indicates the potential of the present material system(s) to be an interesting candidate for future memory design.

Hydroxyapatite-carboxymethyl cellulose-graphene composite coating development on AZ31 magnesium alloy: Corrosion behavior and mechanical properties

In this study, hydroxyapatite (HA) coatings containing carboxymethyl cellulose (CMC) and graphene (Gr) were developed on AZ31 magnesium alloy through two-step electrophoretic deposition method. The morphology and chemical bonding of coatings were characterized and also the phase identification was done using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction, respectively. Moreover, the corrosion behavior of the applied coatings was compared with the bare AZ31 Mg alloy substrate in the simulated body fluid by the means of potentiodynamic polarization test and electrochemical impedance spectroscopy. Obtained results revealed that the novel HA-CMC-Gr coating possesses the highest corrosion resistance compared to the HA, HA-CMC, and HA-Gr coatings due to its uniform and compact structure. To investigate the mechanical properties and to elucidate the effect of CMC on the adhesion of coating-alloy interface, pull-off test was employed, where results demonstrated that the addition of CMC increases the adhesion force from 1.06 MPa to 1.62 MPa. Besides, the modulus of elasticity and the hardness of HA and HA-Gr composite coatings were compared by applying nanoindentation test. Interestingly, it is detected that the presence of Gr has considerably increased the elastic modulus of the coating by approximately 30% in comparison to the pure HA coating.

Guaranteed renewable life insurance under demand uncertainty

AbstractGuaranteed renewability (GR) is a prominent feature in many health and life insurance markets. We develop a model that includes unpredictable (and unobservable) fluctuations in demand for life insurance as well as changes in risk type (observable) over individuals' lifetimes. The presence of demand type heterogeneity leads to the possibility that optimal GR contracts may have a renewal price that is either above or below the actuarially fair price of the lowest risk type in the population. Individuals whose type turns out to be high risk but low demand renew more of their GR insurance than is efficient due to the attractive renewal price. This results in imperfect insurance against reclassification risk. Although a first‐best efficient contract is not possible in the presence of demand type heterogeneity, the presence of GR contracts nonetheless improves welfare relative to an environment with only spot markets.

Characteristics of Electron Transport Study of Composited Graphene-Zinc Oxide Thin Film Photoanode for Dye-Sensitized Solar Cells

Graphene-Zinc Oxide (Gr-ZnO) nanocomposites films were successfully synthesized via facile electrodeposition method in an aqueous solution under Gr concentration conditions. Gr, as a highly conductive carbon, acts as an anchor for ZnO nanosheets and plays a substantial role in controlling the degree of dispersion of ZnO nanosheets onto indium-doped tin oxide (ITO) substrate to form Gr-ZnO nanocomposite. Atomic force microscopy (AFM) and field-emission scanning electron microscopy (FESEM) analysis of Gr-ZnO nanocomposite samples confirmed that the presence of ZnO nanosheets with a high degree of dispersity and crystallinity which is well linked to the thin layer of Gr nanoparticle on ITO substrate. The surface roughness of the films found increased to ~270 nm on Gr-ZnO as compared to Gr ~44 nm and ZnO ~3 nm. Further, the x-ray diffraction spectroscopy (XRD) analysis showed the result is in good agreement with Raman spectroscopy study. The cyclic voltammetry (CV) of Gr-ZnO nanocomposite revealed that the effect of electron-hole recombination process was increased and the presence of Gr in ZnO photoanode provides the fastest redox reaction and hence offers the fastest electron transfer in photoanode.

OR12-03 Mineralocorticoid and Glucocorticoid Receptors Adopt Distinct Quaternary Structures and Can Form Heteromultimers That Affect Chromatin-Binding Profiles

The mineralocorticoid and glucocorticoid receptors (MR and GR) are evolutionarily related nuclear receptors with high sequence conservation and a shared hormone response element (HRE). Both receptors are activated by glucocorticoids, but MR can be selectively activated by aldosterone. Using the imaging technique Number & Brightness (N&B) it has recently been proposed that liganded GR dimers form tetramers upon binding to HREs in live cells. We now show that agonist-bound MR adopts a tetrameric organization in the nucleoplasm and forms complexes with an average of 7 receptor units upon binding an HRE. Interestingly, MR antagonists eplerenone and spironolactone induced intermediate oligomerization arrangements, strongly suggesting that higher order oligomerization is essential for receptor activity. Site-directed mutagenesis and deletion analysis suggest that the N-terminus of MR is a main determinant of higher order oligomerization. Both with corticosterone and aldosterone, GR can incorporate into MR complexes partially displacing MR monomers. Genome-wide chromatin binding studies suggest that the presence of GR in the same cells profoundly change MR interaction with distinct sets of enhancers in a ligand-dependent way, contributing to receptor-specific signaling. Certain genes respond to only one receptor while others respond to both receptors. The interaction of these two closely related receptors has important implications for the mechanisms for glucocorticoid signaling and transcription factors in general.

Surface Energy and Tribology of Electrodeposited Ni and Ni–Graphene Coatings on Steel

Composite electrochemical coatings (CECs) are some of the most widely investigated coatings due to its versatility in tailoring physio-mechanical and tribological properties. The effectiveness of the CECs for tribological applications is dependent on the solid–liquid interfaces. The active and passive nature of the contact boundaries for a CEC with a solid/liquid interface is defined by the surface energy of these boundaries. Unless the effect of surface energy on the tribological properties of the CEC are understood, it is not possible to get a holistic picture on properties, such as corrosion and tribocorrosion. The present study investigates the surface energy of optimized nickel (Ni) and Ni–graphene (Ni–Gr) coatings and their effect on the dynamic friction and wear behavior. It was found that the addition of Gr to the Ni coating in small quantities could decrease the polar component of surface energy significantly than the dispersive component. The presence of Gr in the coating was able to reduce the wear while providing low friction. The Ni–Gr coating exhibited low surface energy that includes weak adhesive forces, which can prevent embedding of the wear particles during sliding.

Prevalence and risk indicators of gingival recessions in an Italian school of dentistry and dental hygiene: a cross-sectional study

The aim of this cross-sectional study is to (i) determine the prevalence, extent, severity, and distribution of gingival recessions and patient perception in a young population and (ii) to identify potential risk indicators. Two hundred fifty-one students with a mean age of 22.9 ± 4.7, attending the School of Dentistry and Dental Hygiene of Vita-Salute San Raffaele University (Milan, Italy) were included. The subjects had undergone a clinical evaluation, by two calibrated examiner, and a questionnaire. Demographic and clinical data were collected to evaluate association of these factors with gingival recessions. The prevalence of gingival recessions at patient and tooth level was 39% and 5.2%, respectively. The only factor associated with the presence of GR was age. On the other hand, age and smoking were associated with the extent, whereas BOP, NCCLs and KT were associated with the severity. Out of 98 subjects presenting at least one GR, 63 (64%) were conscious of the presence of the GR. NCCLs were also strongly associated with the perception of the recession by the patient. There is a low prevalence of buccal gingival recessions in this sample of Italian students. More than 50% of the sample was aware of the problem. Almost all patients presenting symptomatology or aesthetic concern requested appropriate therapy. The findings highlight the low relevance of gingival recessions in daily practice and the importance of controlling potential risk indicators in young populations.

Hybrid nanocomposites prepared from a metal-organic framework of type MOF-199(Cu) and graphene or fullerene as sorbents for dispersive solid phase extraction of polycyclic aromatic hydrocarbons.

Different types of hybrid nanocomposites were prepared from a copper-based metal-organic framework (MOF-199) and graphene (Gr) or fullerene (Fl). The porosity and quality of the nanocomposites were studied by scanning electron microscopy, transmission electron microscopy and BET surface area analysis. The nanocomposites are shown to be viable sorbents for the dispersive micro solid phase extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. This is due to (a) the presence of MOF-199 which leads to improved adsorption capacity, and (b) the presence of Gr or Fl on the surface of MOF-199 which enhances the interaction with PAHs. Specifically, acenaphthene, anthracene, benz[a]anthracene, fluorene, naphthalene, 2-methylnaphthalene, and pyrene were studied. A comparison of the sorbents shows MOF-199/Gr to possess the highest adsorption affinity and to be most durable, probably a result of the high porosity of graphene. Following desorption with acetonitrile, the PAHs were quantified by GC with FID detection. Under the optimum conditions, limits of detection (at an S/N ratio of 3) range from 3 to 10pgmL-1, and the analytical ranges are linear at 0.01-100ngmL-1 of PAHs. The relative standard deviations for five replicates at two spiking levels (0.03 and 50ngmL-1) range from 5.0 to 7.4%. The applicability of this method was confirmed by analyzing spiked real water samples, and recoveries are between 91.9 and 99.5%. Graphical abstract Different types of the hybrid nanocomposites of the copper-based metal-organic framework MOF-199 with graphene or fullerene were synthesized and used as sorbent for the dispersive micro solid phase extraction of polycyclic aromatic hydrocarbons in environmental water samples.