arXiv subjects

K. Bozkurt

Publications and source records attributed to K. Bozkurt.

11 recordsLinked to original sources

arXiv2026

Comprehensive Optical, Electrical and Humidity Sensing Properties of Bifidobacterium infantis 35624 Thin Films

In this study, we present a comprehensive investigation of the structural, optical, and electrical properties of Bifidobacterium longum subsp. longum 35624 (BB35) thin films, and demonstrate their application as a novel relative humidity sensor. UV-Visible spectroscopy revealed that BB35 exhibits two distinct optical absorption regions, corresponding to direct band gaps of 2.1 \pm 0.05 eV and 2.8 \pm 0.05 eV, as confirmed by Tauc plot analysis, establishing BB35 as a genuine wide-bandgap semiconductor material. Photoluminescence measurements under 280 nm excitation exhibited a broad emission spectrum, which was deconvoluted into four Gaussian peaks centered at 434 nm (2.86 eV), 499 nm (2.48 eV), 543 nm (2.3 eV), and 620 nm (2.0 eV), indicating the presence of multiple radiative recombination centers characteristic of semiconducting materials. Electrical characterization revealed dispersive charge transport with current decay following a power-law I \propto t^{-\alpha} (\alpha \approx 0.3), suggesting Poole-Frenkel conduction mechanism typically observed in disordered organic semiconductors. The relative humidity (RH) sensing performance of BB35 films was evaluated using gold interdigital electrodes across 15-90% RH range. The sensor exhibited reversible response with sensitivity increasing linearly from 0.85 to 4.80 as RH increased from 15% to 90%. The devices demonstrated excellent stability over two months with less than 5% degradation in baseline current. These results establish BB35 thin films as a promising eco-friendly semiconducting material for humidity sensing applications and open new avenues for integrating biological materials into electronic and optoelectronic devices.

physics.app-ph↗

arXiv2026

Role of the symmetry energy on hybrid stars

The impact of the symmetry energy on the properties of compact stars is analyzed considering constraints from nuclear physics and astrophysics. A compact star can be a neutron star composed only of nuclear matter or a hybrid star with a quark core. Two typical models (soft and stiff) are considered for the nuclear equation of state, and for the hybrid one, a parameterized first-order phase transition approach, completed with a linear quark matter equation of state, is implemented. We show that the phase transition reduces the tension between GW170817 and NICER observations, and we illustrate the impact of the symmetry energy for the understanding of the nature of the binary system in GW170817. We also confirm our previous findings that the GW170817 waveform is best described as a binary HS with a low-density onset of stiff quark matter. This could also be interpreted as a quarkyonic cross-over.

nucl-th↗

arXiv2024

On the nature of compact stars determined by gravitational waves, radio-astronomy, x-ray emission and nuclear physics

We investigate the question of the nature of compact stars, considering they may be neutron stars or hybrid stars containing a quark core, within the present constraints given by gravitational waves, radio-astronomy, X-ray emissions from millisecond pulsars and nuclear physics. A Bayesian framework is used to combine together all these constraints and to predict tidal deformabilities and radii for a 1.4~M$_\odot$ compact star. We find that present gravitation wave and radio-astronomy data favors stiff nucleonic EoS compatible with nuclear physics and that GW170817 waveform is best described for binary hybrid stars. Binary neutron stars with soft EoS could however not be totally excluded. In all cases, these %In addition, this data favor stiff quark matter, independently of the nuclear EoS, with a low value for the transition density ($n_\mathrm{tr}\in[0.18,0.35]~\mathrm{fm}^{-3}$). Combining these results with constraints from X-ray observation supports the existence $1.4$~M$_\odot$ mass hybrid star, with a radius predicted to be about $R_{1.4}=12.22(45)$~km.

astro-ph.HE↗

arXiv2021

Ground State Properties of Charmed Hypernuclei with Mean Field Approach

Closed shell charmed hypernuclei $^5_{Λ_c}$Li, $^{17}_{Λ_c}$F, $^{41}_{Λ_c}$Sc, $^{57}_{Λ_c}$Cu, $^{133}_{Λ_c}$Sb and $^{209}_{Λ_c}$Bi are calculated within Hartree-Fock approach by using three different force sets derived from microscopic Brueckner-Hartree-Fock calculations of $Λ$ hypernuclei. Ground state properties (binding energies, $Λ_c$ separation energies, $Λ_c$ single particle energies and $Λ_c$ densities) of charmed nuclei are examined. Due to the Coulomb repulsion between protons and the $Λ_c$ baryon, charmed hypernuclei are most bound for $16\leq$A$\leq 41$, where $^{17}_{Λ_c}$F can be considered as an excellent candidate to measure charmed hypernuclei. The competition between the attractive nucleon-$Λ_c$ interaction and the Coulomb repulsion is discussed, and we compare $Λ$ and $Λ_c$ hypernuclei properties.

nucl-th↗

arXiv2020

Multi-messenger and multi-physics Bayesian inference for GW170817 binary neutron star merger

The tidal deformability probability distribution extracted from GW170817 alone, or including multi-messenger information, is confronted to astrophysical and nuclear physics additional constraints within a semi-agnostic approach for the dense matter equation of state. We use Bayesian statistics to combine together low density nuclear physics data, such as the ab-initio predictions based on $χ$EFT interactions or the isoscalar giant monopole resonance, and astrophysical constraints from neutron stars, such as the maximum mass of neutron stars or the probability density function of the tidal deformability $\tildeΛ$ obtained from the GW170817 event. The posteriors probability distribution functions are marginalized over several nuclear empirical parameters ($L_\textrm{sym}$, $K_\textrm{sym}$, $Q_\textrm{sat}$ and $Q_\textrm{sym}$), as well as over observational quantities such as the $1.4M_\odot$ radius $R_{1.4}$ and the pressure at twice the saturation density $P(2n_\textrm{sat})$. The correlations between $L_\textrm{sym}$ and $K_\textrm{sym}$ and between $K_\textrm{sat}$ and $Q_\textrm{sat}$ are also further analyzed. Tension is found between the posteriors: the first one is localized in the tidal deformability probability distribution itself, depending whether multi-messenger analysis is included or not, and the second one is between the observational data and the nuclear physics inputs. These tensions impact the predictions for $L_\textrm{sym}$, $K_\textrm{sym}$ and $R_{1.4}$ with centroids which differ by 2-3$σ$. Implications for the nuclear equation of state are also discussed.

nucl-th↗

arXiv2019

Charge Transport in Bifidobacterium animalis subsp. lactis BB-12 under the various Atmosphere

The influence of relative humidity (RH) on quasistatic current-voltage ${(I-V)}$ characteristics of Bifidobacterium animalis subsp. lactis BB-12 thin layers have been studied for the first time. The value of electrical conductivity in 75$ \%$ RH was found to be in the order of 10$^{-7}$ (ohm cm)$^{-1}$ which was 10$^{6}$ orders of magnitude higher than that observed in dry atmosphere. Here we also demonstrated that RH played a key role in hysteresis behaviour of the measured ${(I-V)}$ characteristics. FTIR measurements showed that under water moisture environment the associated bonds for amine and carboxyl group were greatly strengthened that was the source of number of free charge carries after ionization. The type of surface charge of Bifidobacterium animalis subsp. lactis BB-12 was found to be negative by zeta potential measurements, claiming that electrons were the charge carriers.

physics.bio-ph↗

arXiv2018

$ΛΛ$ pairing in multi-strange hypernuclei

Multi-strange Ca, Sn and Pb hypernuclei with $ΛΛ$ pairing interaction are investigated within the Hartree-Fock-Bogoliubov approach. The unknown $ΛΛ$ pairing strength is calibrated to match with the maximal value for the prediction of the $Λ$ pairing gap in uniform matter for densities and isospin asymmetries equivalent to those existing in multi-$Λ$ hypernuclei. In this way, we provide an upper bound for the prediction of the $Λ$ pairing gap and its effects in hypernuclei. The condensation energy is predicted to be about 3~MeV as a maximum value, yielding small corrections on density distributions and shell structure. In addition, conditions on both Fermi energies and orbital angular momenta are expected to quench the nucleon-$Λ$ pairing for most of hypernuclei.

nucl-th↗

arXiv2017

Multipole excitations in hot nuclei within the finite temperature quasiparticle random phase approximation framework

The effect of temperature on the evolution of the isovector dipole and isoscalar quadrupole excitations in $^{68}$Ni and $^{120}$Sn nuclei is studied within the fully self-consistent finite temperature quasiparticle random phase approximation framework, based on the Skyrme-type SLy5 energy density functional. The new low-energy excitations emerge due to the transitions from thermally occupied states to the discretized continuum at finite temperatures, whereas the isovector giant dipole resonance is not strongly impacted by the increase of temperature. The radiative dipole strength at low-energies is also investigated for the $^{122}$Sn nucleus, becoming compatible with the available experimental data when the temperature is included. In addition, both the isoscalar giant quadrupole resonance and low-energy quadrupole states are sensitive to the temperature effect: while the centroid energies decrease in the case of the isoscalar giant quadrupole resonance, the collectivity of the first $2^{+}$ state is quenched and the opening of new excitation channels fragments the low-energy strength at finite temperatures.

nucl-th↗

arXiv2014

Effect of temperature on the effective mass and the neutron skin of nuclei

We study the finite temperature Hartree-Fock-BCS approximation for selected stable Sn nuclei with zero-range Skyrme forces. Hartree Fock BCS approximation allows for a straightforward interpretation of the results since it involves u and v's which are not matrices as in HFB. Pairing transitions from superfluid to the normal state are studied with respect to the temperature. The temperature dependence of the nuclear radii and neutron skin are also analyzed. An increase of proton and neutron radii is obtained in neutron rich nuclei especially above the critical temperature. Using different Skyrme energy functionals, it is found that the correlation between the effective mass in symmetric nuclear matter and the critical temperature depends on the pairing prescription. The temperature dependence of the nucleon effective mass is also investigated, showing that proton and neutron effective masses display different behavior below and above the critical temperature, due to the small temperature dependence of the density.

nucl-th↗

arXiv2014

Effects of the tensor force on the ground and first $2^{+}$ states of the magic $^{54}$Ca nucleus

The magic nature of the $^{54}$Ca nucleus is investigated in the light of the recent experimental results. We employ both HFB and HF+BCS methods using Skyrme-type SLy5, SLy5+T and T44 interactions. The evolution of the single-particle spectra is studied for the N=34 isotones: $^{60}$Fe, $^{58}$Cr, $^{56}$Ti and $^{54}$Ca. An increase is obtained in the neutron spin-orbit splittings of $p$ and $f$ states due to the effect of the tensor force which also makes $^{54}$Ca a magic nucleus candidate. QRPA calculations on top of HF+BCS are performed to investigate the first $J^π$=$2^{+}$ states of the calcium isotopic chain. A good agreement for excitation energies is obtained when we include the tensor force in the mean-field part of the calculations. The first $2^{+}$ states indicate a subshell closure for both $^{52}$Ca and $^{54}$Ca nuclei. We confirm that the tensor part of the interaction is quite essential in explaining the neutron subshell closure in $^{52}$Ca and $^{54}$Ca nuclei.

nucl-th↗

arXiv2002

Collisional Effects in Isovector Response Function of Nuclear Matter at Finite Temperature

The dipole response function of nuclear matter at zero and finite temperatures is investigated by employing the linearized version of the extended TDHF theory with a non-Markovian binary collision term. Calculations are carried out for nuclear dipole vibrations by employing the Steinwedel-Jensen model and compared with experimental results for $^{120}Sn$ and $^{208}Pb$.

nucl-th↗