A novel digitonin/graphene oxide/iron oxide nanocomposite: synthesis, physiochemical characterization and antioxidant activity

In this work, iron oxide (Fe3O4) magnetic nanoparticles (MNPs) and graphene oxide (GO) nanosheets were prepared via the co-precipitation technique and the Modified Hummer method. Fe3O4 MNPs and GO nanosheets were combined to prepare Fe3O4/GO nanocomposite and subsequently conjugated with Digitonin (DIG) in order to obtain a dual-targeted delivery system based on DIG/Fe3O4/GO nanocomposite. SEM images reveal the presence of Fe3O4 MNPs at a scale of 100 nm, exhibiting dispersion between the GO nanosheets. Aggregation of the DIG/Fe3O4/GO nanocomposite was observed at various size scales. The XRD structural analysis confirms the crystal structure of the prepared samples. The Fe3O4 MNPs demonstrated the main XRD-diffracted peaks. Also, GO nanosheets exhibit crystalline characteristics on the (001) and (002) planes. The predominant peaks observed in the DIG/GO/Fe3O4 nanocomposite are attributed to the crystal phases of Fe3O4 MNPs. The FT-IR vibrational modes observed in the GO/DIG/Fe3O4 nanocomposite indicate the presence of crosslinking between GO nanosheet layers and the Fe3O4 MNPs. The antioxidant activity of the prepared samples was measured and the DIG/GO/Fe3O4 nanocomposite demonstrated a significantly high antioxidant activity in both 2-diphenyl-1-picrylhydrazyl (DPPH·) and 2,2-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS·+) tests.

Novel and flexible asymmetric supercapacitors based on NiCo2O4 nanosheets coated on Al and Cu tapes for wearable devices applications

The binary metal oxides show advantages in energy storage devices. Specifically, nickel cobaltite (NiCo2O4) materials showed promising pseudocapacitive properties, high electrical conductivity and large surface area by virtue of their effective porous structure. NiCo2O4 nanosheets were hydrothermally grown in this work over flexible tapes of Aluminum (Al) and Copper (Cu). A nanosheets structure obtained of NiCo2O4 as confirmed by SEM and AFM images. The measured thickness by 3D profilometer of NiCo2O4 nanosheets based Al framework found to be 4.3 µm compared to 8.4 µm thick of film based-Cu framework. Asymmetric supercapacitor prepared from graphite and NiCo2O4 electrodes separated by filter paper. Acidic aqueous electrolyte of H2SO4 and basic aqueous electrolyte of KOH were employed to verify the cyclic activity and electrochemical reaction of asymmetric prepared supercapacitor devices. The basic KOH electrolyte shows a high stability and better charge transfer/ionic diffusion compared to the acidic H2SO4 electrolyte in particular for NiCo2O4 film-based Cu framework. The energy density and power density values were 0.9 W h kg−1 and 66.45 W kg−1, respectively. The highest specific capacity (in F.g−1) = 10.09 coincides with NiCo2O4/Cu supercapacitor in the basic KOH electrolyte. The charge storage in the supercapacitor system of NiCo2O4 and graphite can be ascribed in the form of Faradic charge transfer and capacitive non-faradic double layer, respectively.

Deeply Virtual Compton Scattering Cross Section at High Bjorken x_{B}

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable x_{B}. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of x_{B}, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75  (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8  (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.

Deep Exclusive Electroproduction of π^{0} at High Q^{2} in the Quark Valence Regime

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of x_{B} (0.36, 0.48, and 0.60) and Q^{2} (3.1 to 8.4  GeV^{2}) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσ_{T}/dt+εdσ_{L}/dt, dσ_{TT}/dt, dσ_{LT}/dt, and dσ_{LT^{'}}/dt are extracted as a function of the proton momentum transfer t-t_{min}. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Ruling out Color Transparency in Quasielastic ^{12}C(e,e^{'}p) up to Q^{2} of 14.2 (GeV/c)^{2}

Quasielastic ^{12}C(e,e^{'}p) scattering was measured at spacelike 4-momentum transfer squared Q^{2}=8, 9.4, 11.4, and 14.2  (GeV/c)^{2}, the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no Q^{2} dependence, up to proton momenta of 8.5  GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured Q^{2} scales in exclusive (e,e^{'}p) reactions. These results impose strict constraints on models of color transparency for protons.

Probing the Deuteron at Very Large Internal Momenta

We measure ^{2}H(e,e^{'}p)n cross sections at 4-momentum transfers of Q^{2}=4.5±0.5  (GeV/c)^{2} over a range of neutron recoil momenta p_{r}, reaching up to ∼1.0  GeV/c. We obtain data at fixed neutron recoil angles θ_{nq}=35°, 45°, and 75° with respect to the 3-momentum transfer q[over →]. The new data agree well with previous data, which reached p_{r}∼500  MeV/c. At θ_{nq}=35° and 45°, final state interactions, meson exchange currents, and isobar currents are suppressed and the plane wave impulse approximation provides the dominant cross section contribution. We compare the new data to recent theoretical calculations, where we observe a significant discrepancy for recoil momenta p_{r}>700  MeV/c.

A small proton charge radius from an electron-proton scattering experiment

Elastic electron-proton scattering (e-p) and the spectroscopy of hydrogen atoms are the two methods traditionally used to determine the proton charge radius, r_p. In 2010, a new method using muonic hydrogen atoms¹ found a substantial discrepancy compared with previous results², which became known as the 'proton radius puzzle'. Despite experimental and theoretical efforts, the puzzle remains unresolved. In fact, there is a discrepancy between the two most recent spectroscopic measurements conducted on ordinary hydrogen^3,4. Here we report on the proton charge radius experiment at Jefferson Laboratory (PRad), a high-precision e-p experiment that was established after the discrepancy was identified. We used a magnetic-spectrometer-free method along with a windowless hydrogen gas target, which overcame several limitations of previous e-p experiments and enabled measurements at very small forward-scattering angles. Our result, r_p = 0.831 ± 0.007_stat ± 0.012_syst femtometres, is smaller than the most recent high-precision e-p measurement⁵ and 2.7 standard deviations smaller than the average of all e-p experimental results⁶. The smaller r_p we have now measured supports the value found by two previous muonic hydrogen experiments^1,7. In addition, our finding agrees with the revised value (announced in 2019) for the Rydberg constant⁸-one of the most accurately evaluated fundamental constants in physics.