Bulgarian Academy of Sciences

Profile Study on Different Patterns in PMMA Bilayer Resist Configurations Under 20 keV Electron Beam Exposure

Electron beam lithography (EBL) using bilayer resists is influenced by electron scattering, proximity effects, resist thickness, pattern density, and exposure dose. Optimization based only on the top-view critical dimension does not capture linewidth variation through the develop...

Impact of Feed Composition and Operating Conditions on Product Yield and Quality, and Cycle Length of an Industrial Hybrid Naphtha Catalytic Reformer

Modern petroleum refining relies heavily on the performance of the catalytic reforming of naphtha, as its liquid product (reformate) provides about 30% of the refinery’s high-octane gasoline pool. The octane number of reformate, its yield, and the cycle length of the naphtha refo...

Seasonal and Interannual Variability of Coastal Black Sea Waters off Bulgaria (2022–2025): A Copernicus Marine Reanalysis Assessment

This study assessed spatial, seasonal, and interannual variability in physical and biogeochemical indicators in surface waters along the Bulgarian Black Sea coast during 2022–2025 to provide an integrated characterization of coastal marine conditions. Copernicus Marine Level 4 mu...

A Generalization of a Classical Geometric Extremum Problem

Let ∂ C be the boundary of a compact convex body C in Rn, n≥2, and O be an interior point of C. Every straight line l containing O cuts from C a segment [AB] with end-points on ∂ C. It is shown that if [AB] is the shortest such segment, then ∂ C is smooth at the points A and B (i...

Enhanced Catalytic Activity of TiO2/rGO Nanocomposites with Squaraine Dye for Photocatalytic Wastewater Treatment

Wastewater treatment has stimulated researchers to develop highly efficient catalysts for the degradation of organic pollutants. The present work focuses on the design and investigation of a titanium dioxide (TiO2)-based photocatalytic system with improved catalytic ability under...

Performance and Upgrade of Trigger Detectors for the BM@N Experiment

Abstract A system of trigger detectors was developed and successfully operated in the BM@N experiment during the 2023 run with 124Xe ion beams at 3.8 A GeV. The trigger detectors are based on plastic scintillators with specialized PMTs and SiPMs operating in the strong magnetic f...

Mathematical model for non-monotone dose response to the PD-L1 blockade in vitro

Abstract Testing of new small molecules for oncotherapy often requires discrimination between the actual, target-specific bioactivity and non-specific toxicity. We present a mathematical model for T-cell reactivation under the action of therapeutic compounds targeting the PD-1/PD...

CAP regime shifts, institutional quality, and technical efficiency in agricultural land use across the EU: A panel stochastic frontier analysis

This study examines how Common Agricultural Policy (CAP) payment intensity and national governance quality jointly shape technical efficiency in agricultural land use. The sample covers the 27 EU member states over 2005–2022, giving 486 balanced observations. We estimate a per-he...

Antifungal Agents of Bacillus velezensis 5RB: Complex Action of Lipopeptides, Polyketides, and Subtilosin A

Bacillus velezensis is a promising candidate for the biocontrol of plant pathogens due to its production of broad-spectrum antimicrobial metabolites. The present study evaluates the antifungal potential and metabolic profile of the non-pathogenic rhizobacterial strain Bacillus ve...

Hydrate-Based Carbon Dioxide Sequestration in the Black Sea: Implications for Turkiye’s Exclusive Economic Zone

Abstract This study evaluates the potential for hydrate-based carbon dioxide (CO2) sequestration within Türkiye’s Exclusive Economic Zone (EEZ) in the Black Sea by mapping the CO2 Hydrate Stability Zone (CHSZ) and estimating storage capacities under different pore-water salinity...

Structure and ac conductivity of K-for-Na ion-exchanged sodium borate glasses

This work addresses structural and ionic transport properties of ion-exchanged borate glasses at temperatures below the glass transition, T g . Analysis of the infrared reflectance spectra of the K-for-Na ion-exchanged glass 0.3Na 2 O-0.7B 2 O 3 revealed short-range order structu...

Direct Immobilization of Living Poly(2-ethyl-2-oxazoline) Chains onto Mesoporous Silica: A Simplified Grafting-To Strategy for Hybrid Organic–Inorganic Materials

The development of straightforward and efficient strategies for the preparation of polymer-functionalized mesoporous silica remains an important challenge in the design of advanced hybrid materials. Herein, we report a novel and simplified approach to the covalent functionalizati...

Structure–Property Relationships of Tungsten Nitride Coatings on Copper Substrates Prepared by Reactive Direct Current Magnetron Sputtering

Tungsten nitride (WN) coatings were deposited on copper substrates by reactive direct current magnetron sputtering using deposition times of 15, 30, 45, and 60 min. The influence of deposition time on the structural, morphological, and electrical properties of the coatings was sy...

Octupole deformation in quasiparticle states of odd-mass and odd-odd nuclei

Abstract As a follow up of [Phys. Scr. 99 055305 (2024)], where we studied axial octupole shapes in two-quasiparticle states of even-even nuclei, we investigate this type of shapes in odd-mass and odd-odd well-deformed nuclei, using the Skyrme-Hartree-Fock-BCS approach with selfc...

On the semigroups of fence-decreasing and fence-preserving transformations on a finite fence

Abstract For a natural number n , a fence [ n ] = {1 ≺ 2 ≻ 3 ≺ 4 ≻ 5 ≺⋯ n } is a partial ordered set. A partial transformation α is called fence-decreasing if xα ⪯ x for all x in the domain of α , and fence-preserving if x ≺ y implies xα ⪯ yα for all x and y in the domain of α ....

Effect of stochasticity on the dynamics of a lac operon model with multiple delays

Abstract We have investigated the stability of a mathematical model of the lac operon with multiple time delays, enhanced with stochastic perturbations. Sufficient conditions for exponential mean square stability have been used to determine analytical threshold values. Numerical...

Towards resilient forest establishment in Europe: functional traits, genetic diversity and multifunctional design

Abstract Forest restoration and afforestation across Europe are accelerating, yet the decision-making processes governing forest establishment remain unevenly examined, especially from a biodiversity perspective. Considering this and the global environmental changes of climate sh...

Quantification of absolute IgG concentration in bat sera

Abstract Bats are endowed with a remarkable capacity to withstand important pathogens through evolutionary adaptations in their immune systems. Antibodies are essential component of the adaptive immune response and serve as a crucial biomarker, indicating both present and past pa...

Geometry-Based Description for Hydrogen Bond Organization in Small Water Clusters Derived from Spectroscopic and Quantum Chemical Data

Hydrogen-bond organization plays a central role in determining the structure and properties of water from molecular to macroscopic scales. In this study, we propose a geometry-based descriptor for small hydrogen-bonded water clusters, (H2O)n, with n = 2–6. The central element of...

Tips and Tricks for Small Molecule and Force Field Parametrization

In order to be productive in drug design and materials science, molecular dynamics force fields need to possess quality and fidelity that allow researchers to observe phenomena in simulation before observing them in experiment. The inverse scenario parameters and force fields tha...