An efficient magnetic resonance imaging (MRI) contrast agent with a high R2 relaxivity value is achieved by controlling the shape of iron oxide to rod like morphology with a length of 30-70 nm and ...diameter of 4-12 nm. Fe3O4 nanorods of 70 nm length, encapsulated with polyethyleneimine show a very high R2 relaxivity value of 608 mM(-1) s(-1). The enhanced MRI contrast of nanorods is attributed to their higher surface area and anisotropic morphology. The higher surface area induces a stronger magnetic field perturbation over a larger volume more effectively for the outer sphere protons. The shape anisotropy contribution is understood by calculating the local magnetic field of nanorods and spherical nanoparticles under an applied magnetic field (3 Tesla). As compared to spherical geometry, the induced magnetic field of a rod is stronger and hence the stronger magnetic field over a large volume leads to a higher R2 relaxivity of nanorods.
This study stabs to probe the impact of financial development, urbanization, trade openness, political institutions, and energy consumption on the ecological footprints (EF), within the framework of ...EKC, of 110 countries congregated by income levels, over the time span of 1996–2016. The final outcome of cross-sectionally weighted Panel EGLS and multi-step A-B GMM evidently reinforced the existence of EKC hypothesis in case of EF both in developed and less-developed countries. This study finds the destructive environmental impact of composition effect and energy consumption while political institutions, trade openness, and urbanization have constructive environmental effect. Financial development reduces the human demand on nature only in less-developed countries. The ultimate consequences of this study are equipped with several policy recommendations for the concerned authorities.
Graphene quantum dots (GQDs) the quantum dot variety of graphene represent a new group of quantum dots with exciting properties. Herein we report the electrochemical synthesis of GQDs with size ...ranging from 3 to 5 nm in diameter from graphene oxide (GO) at room temperature with LiClO4 in propylene carbonate as the electrolyte. The size of the GQDs can be tuned by playing with different parameters such as the applied potential, oxidation and reduction time, concentration of the supporting electrolyte. GQDs are promising candidate for humidity sensors, chemical sensors, nanoelectronic devices and biomarkers. In this paper, the potential use of the GQD as soil moisture sensors is also explored. We fabricated the micro-sensor where GQDs is used as the sensing material to perform the soil moisture measurements on two different soils. In our study, we observed that when soil water content varies from 0% to 32%, then sensor resistance changes by 99% and 97% for the red soil (silt loam) and black soil (clayey), respectively. We found that sensor response time was around 180 s for the both silt loam and clayey soils.
Display omitted
•Graphene quantum dots (GQDs) is synthesized from graphene oxide by electrochemical method.•The method is a room temperature synthesis process with control over the size of the GQDs.•Micro-sensor is fabricated and the soil moisture sensing properties of the GQDs on two different soil types are studied.•The passivated GQDs sensor is compared with the as-prepared GQDs sensor.•The sensing mechanism is explained by the H-bonding between GQDs and water molecules.
The local interstellar spectra (LISs) for galactic cosmic rays (CRs) cannot be directly observed at the Earth below certain energies, because of solar modulation in the heliosphere. With Voyager 1 ...crossing the heliopause in 2012, in situ experimental LIS data below 100 MeV/nuc can now constrain computed galactic CR spectra. Using galactic propagation models, galactic electron, proton, and light nuclei spectra can now be computed more reliably as LISs. Using the Voyager 1 observations made beyond the heliopause, and the observations made by the PAMELA experiment in Earth orbit for the 2009 solar minimum, as experimental constraints, we simultaneously reproduced the CR electron, proton, helium, and carbon observations by implementing the GALPROP code. Below about 30 GeV/nuc solar modulation has a significant effect and a comprehensive three-dimensional (3D) numerical modulation model is used to compare the computed spectra with the observed PAMELA spectra at these energies. Subsequently the computed LISs can be compared over as wide a range of energies as possible. The simultaneous calculation of CR spectra with a single propagation model allows the LISs for positrons, boron, and oxygen to also be inferred. This implementation of the comprehensive galactic propagation model (GALPROP), alongside a sophisticated solar modulation model to compute CR spectra for comparison with both Voyager 1 and PAMELA observations over a wide energy range, allows us to present new self-consistent LISs (and expressions) for electrons, positrons, protons, helium, carbon, boron, and oxygen for the energy range of 3 MeV/nuc-100 GeV/nuc.
Herein, we report the optical and magnetic properties of Mn- and Co-doped ZnO nanorods fabricated via a simple one-step aqueous-based chemical method. Interestingly, SEM results reveal a uniform size ...distribution of the nanorods throughout the substrate. The UV emission band of doped ZnO nanorods reveals a red shift from 382 to 384.5 nm, indicating a band-edge bending due to the dopants. The defect-related band centered at 600 nm is suppressed (I D/I UV = 1−0.35) considerably in doped nanorods, revealing the quenching of surface defects present in the nanostructures. XRD, XPS, Raman spectra, and EDS data demonstrate a successful incorporation of TM dopants in ZnO nanorods. Localized SAED patterns taken using nanoprobe size reveals that the nanorods are single crystals, grown along the c-axis 0002 direction. A systematic evalution of the enhancement in ferromagnetism (M = 0.15 × 10−2 to 1.3 × 10−2 emu/g) is found in modified doped ZnO nanorods.
During neuronal development, β-actin serves an important role in growth cone mediated axon guidance. Consistent with this notion, in vivo ablation of the β-actin gene leads to abnormalities in the ...nervous system. However, whether β-actin is involved in the regulation of neuronal gene programs is not known. In this study, we directly reprogramed β-actin+/+ WT, β-actin+/- HET and β-actin-/- KO mouse embryonic fibroblast (MEFs) into chemically induced neurons (CiNeurons). Using RNA-seq analysis, we profiled the transcriptome changes among the CiNeurons. We discovered that induction of neuronal gene programs was impaired in KO CiNeurons in comparison to WT ones, whereas HET CiNeurons showed an intermediate levels of induction. ChIP-seq analysis of heterochromatin markers demonstrated that the impaired expression of neuronal gene programs correlated with the elevated H3K9 and H3K27 methylation levels at gene loci in β-actin deficient MEFs, which is linked to the loss of chromatin association of the BAF complex ATPase subunit Brg1. Together, our study shows that heterochromatin alteration in β-actin null MEFs impedes the induction of neuronal gene programs during direct reprograming. These findings are in line with the notion that H3K9Me3-based heterochromatin forms a major epigenetic barrier during cell fate change.
In humans, the cytosolic glutathione S-transferase (GST) family of proteins is encoded by 16 genes presented in seven different classes. GSTs exhibit remarkable structural similarity with some ...overlapping functionalities. As a primary function, GSTs play a putative role in Phase II metabolism by protecting living cells against a wide variety of toxic molecules by conjugating them with the tripeptide glutathione. This conjugation reaction is extended to forming redox sensitive post-translational modifications on proteins: S-glutathionylation. Apart from these catalytic functions, specific GSTs are involved in the regulation of stress-induced signaling pathways that govern cell proliferation and apoptosis. Recently, studies on the effects of GST genetic polymorphisms on COVID-19 disease development revealed that the individuals with higher numbers of risk-associated genotypes showed higher risk of COVID-19 prevalence and severity. Furthermore, overexpression of GSTs in many tumors is frequently associated with drug resistance phenotypes. These functional properties make these proteins promising targets for therapeutics, and a number of GST inhibitors have progressed in clinical trials for the treatment of cancer and other diseases.
We observed Verwey transition in very small (6–14 nm) amine-coated octahedral magnetite (Fe3O4) nanoparticles that is not present in spherical similarly sized (4–13 nm) nanoparticles. Electron ...microscopy shows that octahedral nanoparticles have {111} facets with better cationic coordination symmetry as their surface. Spherical shape illustrates conventional superparamagnetic behavior; on the contrary, a characteristic Verwey transition near 120 K is prominent in field-cooled/zero-field-cooled curves of octahedral nanoparticles. Higher saturation magnetization in octahedral nanoparticles indicates lesser surface spin disorder and well-established anisotropy. Better surface coordination offers a reduced number of oxygen vacancies at the surface and, therefore, better stoichiometry results in a Verwey transition in octahedral nanoparticles. Electrical resistivity measurements show a sharp change in resistance for octahedral particles below the Verwey transition temperature which is completely hindered in spherical particles. The electrical transport characteristics indicate that these nanoparticle assemblies or thin films could be useful for future generation switching and memory devices.
We analyze the hidden charm
P
-wave tetraquarks in the diquark model, using an effective Hamiltonian incorporating the dominant spin–spin, spin–orbit and tensor interactions. We compare with other
P
...-wave systems such as
P
-wave charmonia and the newly discovered
Ω
c
baryons, analysed recently in this framework. Given the uncertain experimental situation on the
Y
states, we allow for different spectra and discuss the related parameters in the diquark model. In addition to the presently observed ones, we expect many more states in the supermultiplet of
L
=
1
diquarkonia, whose
J
PC
quantum numbers and masses are worked out, using the parameters from the currently preferred
Y
-states pattern. The existence of these new resonances would be a decisive footprint of the underlying diquark dynamics.
A
bstract
The LHCb collaboration have recently updated their analysis of the resonant
J/ 𝜓 p
mass spectrum in the decay
Λ
b
0
→ J/𝜓 p K
−
, making use of their combined Run 1 and Run 2 data. In the ...updated analysis, three narrow states,
P
c
(4312)
+
,
P
c
(4440)
+
, and
P
c
(4457)
+
, are observed. The spin-parity assignments of these states are not yet known. We interpret these narrow resonances as compact hidden-charm diquark-diquark- antiquark pentaquarks. Using an effective Hamiltonian, based on constituent quarks and diquarks, we calculate the pentaquark mass spectrum for the complete SU (3)
F
lowest
S
- and
P
-wave multiplets, taking into account dominant spin-spin, spin-orbit, orbital and tensor interactions. The resulting spectrum is very rich and we work out the quark flavor compositions, masses, and
J
P
quantum numbers of the pentaquarks. However, heavy quark symmetry restricts the observable states in Λ
b
-baryon, as well as in the decays of the other weakly-decaying
b
-baryons, Ξ
b
and Ω
b
. In addition, some of the pentaquark states are estimated to lie below the
J/ 𝜓 p
threshold in Λ
b
-decays (and corresponding thresholds in Ξ
b
- and Ω
b
-decays). They decay via
c
c
¯
annihilation into light hadrons or a dilepton pair, and are expected to be narrower than the
P
c
-states observed. We anticipate their discovery, as well as of the other pentaquark states present in the spectrum at the LHC, and in the long-term future at a Tera-
Z
factory.
PDF
