Browsing by Issue Date, starting with "2026"

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Access status: Open Access ,
Modulating Surface Properties and Osteoblast Responses in Bone Regeneration via Positive and Negative Charges during Electrospinning of Poly(L‑lactide-co-ε-caprolactone) (PLCL) Scaffolds
(2026) Marszalik, Katarzyna; Polak, Martyna; Berniak, Krzysztof; Knapczyk-Korczak, Joanna; Szewczyk, Piotr K.; Marzec, Mateusz M.; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki Przemysłowej
The global demand for faster and more effective bone regeneration calls for biomimetic scaffolds that actively guide cell behavior beyond providing structural support. Electrospinning offers unique opportunities to tailor scaffold properties, yet the influence of positive and negative voltage polarities during fabrication on cell−material interactions remains largely unexplored. Here, we investigate poly(L-lactide-co-ε-caprolactone) (PLCL) scaffolds, a statistical copolymer combining strength and elasticity, produced under positive (PLCL+) and negative (PLCL−) polarity. Both scaffold types display comparable morphologies and bulk chemistry. However, X-ray photoelectron spectroscopy reveals charge dependent surface chemistry, with PLCL− enriched in O C and O−C groups. Zeta potential results highlight pronounced voltage polarity effects under aqueous conditions at pH 7.5, showing −29.19 mV for PLCL+ and −34.77 mV for PLCL−. Biologically, both scaffolds support rapid osteoblast attachment, with robust filopodia and collagen type I deposition by day 14. Strikingly, PLCL+ scaffolds promote deeper cellular infiltration and broader cytoskeletal distribution, whereas PLCL− scaffolds enhance proliferation, but with a flatter cell morphology. These findings reveal that subtle, charge-driven surface chemical differences in random copolymer scaffolds profoundly modulate osteoblast behavior. This work identifies electrospinning voltage polarity as a powerful yet underutilized design parameter for engineering next-generation scaffolds for bone tissue regeneration.
Access status: Open Access ,
Controlled exsolution-dissolution in double perovskites enables symmetrical-capable high-performance SOFC electrodes
(2026) Lach, Jakub; Zheng, Kun; Radu, Cristian; Kryński, Marcin; Gogacz, Michał; Ling, Yihan; Klimkowicz, Alicja; Łapiński, Marcin
Wydział Energetyki i Paliw
In situ exsolution has emerged as a powerful strategy for tailoring fuel electrode catalysts in solid oxide fuel cells (SOFCs), yet its integration with reversible exsolution-dissolution processes and its application to symmetrical-capable electrode design remain largely unexplored. Here, we demonstrate controlled exsolution-dissolution in nanofiber double perovskites as a rational route to engineer high-performance SOFC electrodes operable in both symmetrical and anode-supported configurations. $Sm_{0.9}Ba_{0.9}Mn_{1.8−x}Fe_{x}Co_{0.1}Ni_{0.1}O_{5+δ}$ nanofiber perovskites enable composition-dependent control of nanoparticle evolution. Under reducing conditions, socketed Co–Ni–Fe alloy nanocatalysts exsolve and partially embed into the perovskite lattice, while oxidation induces their transformation into $Fe_{3−x−y}Ni_{x}Co_{y}O_{4}$-type hollow core–shell nano-oxides via a Kirkendall-type mechanism. The nanofiber architecture promotes smaller and more densely distributed nanoparticles compared to powders, enhancing catalytic activity and redox stability. The optimized composite electrode delivers a low polarization resistance of 0.046 Ω cm2 at 800 °C. Anode-supported cells achieve a peak power density of 1112 mW cm−2 at 850 °C and 877 mW cm−2 at 800 °C, while symmetrical cells deliver 816 mW cm−2 at 800 °C with stable operation. This work establishes controlled exsolution-dissolution as a versatile platform for designing symmetrical-capable high-performance SOFC electrodes and highlights hollow core–shell nanostructure engineering as a powerful strategy for durable solid oxide electrochemical systems.
Access status: Open Access ,
Systems of differential inclusions with competing operators and variable exponents
(Wydawnictwa AGH, 2026) Vetro, Francesca; Efendiev, Rakib
In this paper, we study a system of differential inclusions with Dirichlet boundary condition, involving competing operators and variable exponents. More precisely, we investigate the existence of both generalized solutions and weak solutions to the problem under consideration. In order to archive our results, we make use of approximation through finite dimensional subspaces via a Galerkin basis along with minimization and nonsmooth analysis.
Access status: Open Access ,
Time-Frequency Token Advantage Clipping for Training Efficient Large Reasoning Model
(2026) Bao, Rong; Wang, Bo; Li, Hongyu; Zheng, Riu; Wang, Xiao; Rutkowski, Leszek; Zhang, Qi; Ding, Liang; Tao, Dacheng
Wydział Informatyki
Long Chain-of-Thought (CoT) reasoning enhances large reasoning models’ performance but suffers from severe inefficiencies, as models often overthink simple problems or underthink complex ones. Current sequence-level optimizations, like length penalties, are too coarse-grained to distinguish core logic from verbose language, precluding the necessary token-level control for efficient reasoning CoT. To overcome these limitations, we introduce Time-Frequency token Advantage Clipping (TFAC), a novel training framework designed to build efficient large reasoning models via token-level interventions. Specifically, TFAC functions along two dimensions: 1) The Frequency Dimension: It discourages inefficient loops and encourages deeper exploration by dynamically reducing the advantage scores of high-entropy tokens that are repeatedly generated within a single reasoning path. 2) The Time Dimension: It reduces excessive overthinking of the system by establishing a historical baseline for the occurrence count of each critical token in previously successful trajectories, and clipping the advantages of tokens that exceed this baseline during training. Crucially, to preserve the model’s exploratory capabilities on novel problems, this suppression mechanism is automatically disabled when no historical record of success is available. Experiments conducted on the Deepseek-Distill-32B and Qwen3- 8B models show that TFAC outperforms leading baseline methods, improving performance by 2.3 and 3.1 percentage points, respectively, while simultaneously reducing inference costs by 35% and 28% in scenarios where correct answers are generated. These results validate the significant efficacy of TFAC in training large reasoning models that are both powerful and highly efficient. The source code and datasets used in this study are available at https://github.com/rbao2018/TFAC.
Access status: Open Access ,
Bridging the Tokenizer Gap: Semantics and Distribution-aware Knowledge Transfer for Unbiased Cross-Tokenizer Distillation
(2026) Wang, Huazheng; Jing, Yongcheng; Sun, Haifeng; Wang, Jingyu; Liao, Jianxin; Rutkowski, Leszek; Tao, Dacheng
Wydział Informatyki
Cross-tokenizer knowledge distillation, where the teacher and student employ different tokenizers, is becoming increasingly prevalent, yet it poses underexplored challenges: existing methods fail to capture the rich knowledge encoded in teacher logits, as evidenced by the neglect of semantic information, inaccurate and biased logit alignment, and discarding distributional structure—ultimately leading to unfavorable distillation. To address these issues, we propose SEDI, a semantics and distribution-aware knowledge transfer framework tailored for cross-tokenizer distillation. To preserve factual knowledge, SEDI employs bipartite graph-based alignment at the tokenization level and a sliding window re-encoding strategy at the vocabulary level, enabling unbiased transfer of the teacher’s next-token predictions into the student’s vocabulary space. To further retain distributional information, we align the student’s entropy with that of the teacher by incorporating the student’s own logits during training, which helps to mitigate the exposure bias problem. Experiments on ten datasets across three task domains and five different teacher-student model pairs with varying vocabulary sizes demonstrate that SEDI delivers substantial improvements, with gains of up to 19.8 .
Access status: Open Access ,
Anisotropic singular logistic equations
(Wydawnictwa AGH, 2026) Da Silva, João Pablo Pinheiro; Failla, Giuseppe; Gasiński, Leszek; Papageorgiou, Nikolaos S.
We consider a parametric Dirichlet problem driven by the anisotropic $(p,q)$-Laplacian and a reaction with a singular term and a superdiffusive logistic perturbation. We prove an existence and nonexistence theorem which is global with respect to the parameter $\lambda\gt 0$.We consider a parametric Dirichlet problem driven by the anisotropic $(p,q)$-Laplacian and a reaction with a singular term and a superdiffusive logistic perturbation. We prove an existence and nonexistence theorem which is global with respect to the parameter $\lambda\gt 0$.
Access status: Open Access ,
p-type graphitic carbon nitride with boron bridge atoms designed for photoelectrochemical conversion of CO2
(2026) Mech, K.; Sławek, A.; Podborska, A.; Abdi, G.; Muzaffar, S.; Jarczewski, S.; Sokołowski, K.; Musielak, B.; Cechosz, E.; Janioł, M.; Szaciłowski, K.; Ponce de Leon, C.
Akademickie Centrum Materiałów i Nanotechnologii
Here, we report the results of studies dedicated to a synthesis of a series of graphitic carbon nitride materials doped with different amounts of boron, designed for photoelectrochemical conversion of CO2. The crystallographic structure of B-doped and pure heptazines was analyzed using XRD, while their chemical structure was analyzed using NMR, XAS, XPS, and FTIR spectroscopy. Based on of experimental spectra and DFT-based ones, we proved that boron in the polyheptazine structure is incorporated through the substitution of N atoms located only in bridge positions. The carbon nitride materials were also characterized in terms of their band structure based on the results of DRS spectroscopy, Mott-Schottky analysis, and DFT modelling. The experimental band gap energies and the decrease of band gap values resulting from the presence of boron bridge atoms were also confirmed by DFT calculations. The localization of valence and conduction bands indicates, along with p-type conductivity resulting from the presence of boron in these specific sites, that B-doped g-C3N4 may be utilized for light-supported PEC conversion of CO2. Photoluminescence measurements demonstrate more effective charge separation and significantly longer charge carrier lifetime resulting from the incorporation of boron. Finally, photocurrent spectroscopy showed that the material containing 2.5 at. % of B (B1–CN) generates photocurrent of the highest intensity of -0.99 μA in CO2-saturated 0.5 M KHCO3, making it the most promising one for photoelectrochemical conversion of CO2. The GC-MS/TCD analysis of syngas produced during photoelectrochemical CO2 reduction confirmed the formation of H2 and CO.
Access status: Open Access ,
High-Volume Return Premium on the Warsaw Stock Exchange: evidence, drivers, and strategy design
(Wydawnictwa AGH, 2026) Sieradzan, Olga; Wójtowicz, Tomasz
This paper investigates the High-Volume Return Premium (HVRP) on the Warsaw Stock Exchange from 2002 to 2023. Building on prior research, it tests whether an unusually high trading volume predicts short-term return anomalies. Using daily data and long-only strategies based on relative trading volume, the study confirms the existence of the HVRP, with the strongest effects observed over one-day horizons, particularly for mid-cap and low-priced stocks. The premium weakens with longer holding periods and lower trading activity. These findings indicate that trading volume carries predictive information in an emerging market context and that volume-based signals can generate exploitable short-term return patterns. However, practical constraints such as transaction costs may limit the real-world profitability of such strategies.
Access status: Open Access ,
2030 roadmap on two-dimensional materials for energy storage and conversion
(2026) Ding, Lan; Qi, Kezhen; Huang, Zimo; Yu, Ying; Yang, Ze; Tabibi, Sepehr; Khataee, Alireza; Hao, Lei; Zhang, Qitao; Popkov, Vadim; Kaneva, Maria; Lobinsky, Artem; Yu, Zhipeng; Li, Jun; Sultan, Amir; Zheng, Kun; Qu, Gan; Ma, Dandan; Shi, Jian-Wen; Ismail, Ahmed
Wydział Energetyki i Paliw
Two-dimensional (2D) materials have rapidly emerged as transformative platforms for energy storage and conversion, owing to their atomic-scale thickness, tunable electronic structures, and versatile chemical functionalities. Over the past five years, remarkable advances in material synthesis, interface engineering, and device integration have unlocked new opportunities, yet challenges in stability, scalability, and performance optimization remain. In this roadmap, we provide an updated perspective toward 2030, systematically reviewing eleven representative 2D material classes, which can be broadly grouped into carbon-based materials, inorganic semiconductors, framework materials, and layered nanosheet systems. Their opportunities and challenges in electrochemical energy storage, photocatalysis, and electrocatalysis are highlighted. We believe this roadmap can enrich the development of 2D materials for sustainable energy technologies, and provide useful guidance for both fundamental studies and practical applications in the coming decade.
Access status: Open Access ,
SRD: Reinforcement-Learned Semantic Perturbation for Backdoor Defense in VLMs
(2026) Xu, Shuhan; Liang, Siyuan; Zheng, Hongling; Liu, Aishan; Wang, Xinbiao; Luo, Yong; Lin, Fu; Rutkowski, Leszek; Tao, Dacheng
Wydział Informatyki
Visual language models (VLMs) have made significant progress in image captioning tasks, yet recent studies have found they are vulnerable to backdoor attacks. Attackers can inject undetectable perturbations into the data during inference, triggering abnormal behavior and generating malicious captions. These attacks are particularly challenging to detect and defend against due to the stealthiness and cross-modal propagation of the trigger signals. In this paper, we identify two key vulnerabilities by analyzing existing attack patterns: (1) the model exhibits abnormal attention concentration on certain regions of the input image, and (2) backdoor attacks often induce semantic drift and sentence incoherence. Based on these insights, we propose Semantic Reward Defense (SRD), a reinforcement learning framework that mitigates backdoor behavior without requiring any prior knowledge of trigger patterns. SRD learns to apply discrete perturbations to sensitive contextual regions of image inputs via a deep Q-network policy, aiming to confuse attention and disrupt the activation of malicious paths. To guide policy optimization, we design a reward signal named semantic fidelity score, which jointly assesses the semantic consistency and linguistic fluency of the generated captions, encouraging the agent to achieve a robust yet faithful output. SRD offers a trigger-agnostic, policy-interpretable defense paradigm that effectively mitigates local (TrojVLM) and global (Shadowcast) backdoor attacks, reducing ASR to 3.4% and 5.6% respectively, with less than 15% average CIDEr drop on the clean inputs. Our codes can be found at https://github.com/ Ciconey/SRD.git.
Access status: Open Access ,
Monitoring stateczności wyrobisk górniczych i tunelowych
(Wydawnictwa AGH, 2026) Małkowski, Piotr; Niedbalski, Zbigniew; Bednarek, Łukasz
Wydział Inżynierii Lądowej i Gospodarki Zasobami
Access status: Open Access ,
New type of composite hydrogel based on natural polysaccharides and sodium polyacrylate for the production of fire-resistant fabrics
(2026) Osabe, Ryoko; Mastalska-Popławska, Joanna; Rutkowski, Paweł; Suematsu, Hisayuki; Kata, Dariusz; Szumera, Magdalena; Majka, Tomasz M.
Wydział Inżynierii Materiałowej i Ceramiki
Flexible and fire-resistant hydrogel–cotton fabric composites doped with ceramic fire retardants were obtained by the immersion method. Among the analyzed mixtures, the samples based on sodium polyacrylate, which provided the best degree of penetration and subsequent intumescence, and those containing magnesium hydroxide in their composition had the best fire-resistant parameters. This was confirmed based on TG/DSC and DMA thermal analysis, PCFC measurements, reaction to fire test results, and SEM microphotographs. The MIR spectroscopic analysis additionally proved that the fire-retardant mechanism is based on the creation of an intumescent structure strengthened by the interaction of fire retardants with various functions, such as hydroxides, which, during decomposition, create a protective char around the material. We believe that these results will contribute to the development of special fabrics with fire-retardant properties.
Access status: Open Access ,
Comparative Physicochemical Characterization of Electrospun PCL, PLLA, and PLCL Scaffolds and Cell Responses for Tissue Engineering Applications
(2026) Polak, Martyna; Neela, Nagalekshmi Uma Thanu Krishnan; Berniak, Krzysztof; Knapczyk-Korczak, Joanna; Szewczyk, Piotr K.; Marzec, Mateusz M.; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki Przemysłowej
In tissue engineering, electrospun scaffolds are valued for their tunable features, which direct cell behavior. Within this study, we electrospun scaffolds from three common polyesters: polycaprolactone (PCL), poly(L-lactic acid) (PLLA), and poly(lactide-co-caprolactone) (PLCL), to identify differences in cell–material interactions. PLLA fibers had the largest average diameter (2.6 ± 0.2 µm), PLCL fiber diameter was intermediate (2.2 ± 0.5 µm), and PCL was the smallest (1.1 ± 0.6 µm). Additionally, X-ray photoelectron spectroscopy (XPS) revealed distinct surface chemistries that are correlated with streaming potential results at pH 7.4. PLCL fibers showed the most negative zeta potential (−36.4 ± 0.7 mV), followed by PLLA (−28.4 ± 0.8 mV) and PCL (−24.0 ± 0.5 mV). Mechanical testing indicates the highest strength for PLCL mats (5.6 ± 0.9 MPa), then PLLA (3.5 ± 0.3 MPa) and PCL (1.9 ± 0.1 MPa). Cell studies indicated lower initial adhesion of osteoblasts on PLCL (∼53%↓) and PLLA (∼73.6%↓) vs. PCL, likely reflecting PCL scaffold morphology; however, viability at 3 and 7 days was significantly higher on PLCL and PLLA. Microscopy studies confirmed greater filopodia and cell spreading on PLCL and PLLA. Overall, all three are suitable scaffold materials, with PLCL and PLLA supporting cytoskeleton organization and viability better.
Access status: Open Access ,
Parametric formal Gevrey asymptotic expansions in two complex time variable problems
(Wydawnictwa AGH, 2026) Chen, Guoting; Lastra, Alberto; Malek, Stéphane
The analytic and formal solutions to a family of singularly perturbed partial differential equations in the complex domain involving two complex time variables are considered. The analytic continuation properties of the solution of an auxiliary problem in the Borel plane overcomes the absence of adequate domains which would guarantee summability of the formal solution. Moreover, several exponential decay rates of the difference of analytic solutions with respect to the perturbation parameter at the origin are observed, leading to several asymptotic levels relating the analytic and the formal solution
Access status: Open Access ,
Calderón-Hardy type spaces and the Heisenberg sub-Laplacian
(Wydawnictwa AGH, 2026) Rocha, Pablo
For $0 \lt p \leq 1 \lt q \lt \infty$ and $\gamma \gt 0$, we introduce the Calderón-Hardy spaces $\mathcal{H}^{p}_{q,\gamma}(\mathbb{H}^{n})$ on the Heisenberg group $\mathbb{H}^{n}$, and show for every $f \in H^{p}(\mathbb{H}^{n})$ that the equation \[\mathcal{L}F=f\] has a unique solution $F$ in $\mathcal{H}^{p}_{q,2}(\mathbb{H}^{n})$, where $\mathcal{L}$ is the sub-Laplacian on $\mathbb{H}^{n}$, \[1 \lt q \lt \frac{n+1}{n} \quad \text{and} \quad (2n+2)\left(2+\frac{2n+2}{q}\right)^{-1} \lt p \leq 1.\]
Access status: Open Access ,
On the existence of independent (1,k) -dominating sets for k∈{1,2} in two products of graphs
(Wydawnictwa AGH, 2026) Bednarz, Paweł; Michalski, Adrian; Paja, Natalia
A subset $J$ of vertices is said to be a $(1,k)$-dominating set if every vertex $v$ not belonging to the set $J$ has a neighbour in $J$ and there exists also another vertex in $J$ within the distance at most $k$ from $v$. In this paper, we study the problem of the existence of independent $(1,k)$-dominating sets for $k\in\{1,2\}$ in the tensor product and in the strong product of two graphs. We give complete characterisations of these graph products, which have independent $(1,1)$-dominating sets or independent $(1,2)$-dominating sets, with respect to the properties of their factors.
Access status: Open Access ,
Galerkin-type minimizers to a competing problem for (p, q)-Laplacian with variable exponents
(Wydawnictwa AGH, 2026) Zhang, Zhenfeng; Ghasemi, Mina; Vetro, Calogero
This study focuses on a sequence of approximate minimizers for the functional \[J(u)=\int\limits_{\Omega}\sum\limits_{i=1}^{N}\frac{1}{p_{i}(x)}\bigg|\frac{\partial u}{\partial x_{i}}\bigg|^{p_{i}(x)}dx-\mu\int\limits_{\Omega}\sum\limits_{i=1}^{N}\frac{1}{q_{i}(x)}\bigg|\frac{\partial u}{\partial x_{i}}\bigg|^{q_{i}(x)}dx-\int\limits_{\Omega} F(u(x))dx,\] where $\Omega\subset\mathbb{R}^N$ ($N\geq 3$) is a bounded domain, and $p_i,q_i\in C(\overline{\Omega})$ with $1\lt p_i,q_i\lt +\infty$ for all $i \in \{1,\ldots,N\}$. We establish the convergence result to the infimum of $J(u)$ when $F:\mathbb{R}\to\mathbb{R}$ is a locally Lipschitz function of controlled growth, following the Galerkin method. As an application, we establish the existence of solutions to a class of Dirichlet inclusions associated to the functional.
Access status: Open Access ,
Damped nonlinear Ginzburg-Landau equation with saturation. Part II. Strong Stabilization
(Wydawnictwa AGH, 2026) Bégout, Pascal; Díaz, Jesús Ildefonso
We study the complex Ginzburg-Landau equation posed on possibly unbounded domains, including some singular and saturated nonlinear damping terms. This model interpolates between the nonlinear Schrödinger equation and dissipative parabolic dynamics through a complex time-derivative prefactor, capturing the interplay between dispersion and dissipation. As a continuation of our previous study on the existence and uniqueness of solutions, we prove here some strong stabilization properties. In particular, we show the finite time extinction of solutions induced by the nonlinear saturation mechanism, which, sometimes, can be understood as a bang-bang control. The analysis relies on refined energy methods. Our results provide a rigorous justification of nonlinear dissipation as an effective stabilization mechanism for this class of complex equations where the maximum principle fails.
Access status: Open Access ,
Solutions with prescribed mass for a critical Choquard equation driven by a local-nonlocal operator
(Wydawnictwa AGH, 2026) Nidhi, Nidhi; Sreenadh, Konijeti
In this paper, we study the normalized solutions of the following critical growth Choquard equation with mixed local and nonlocal operators: \[\begin{split}-\Delta u +(-\Delta)^s u &= \lambda u +\mu |u|^{p-2}u +(I_{\alpha}*|u|^{2^*_{\alpha}})|u|^{2^*_{\alpha}-2}u \quad\text{in}\quad \mathbb{R}^N,\\ \| u\|_2 &= \tau,\end{split}\] where $N\geq 3$, $\tau\gt 0$, $I_{\alpha}$ is the Riesz potential of order $\alpha\in (0,N)$, $2^*_{\alpha}=\frac{N+\alpha}{N-2}$ is the critical exponent corresponding to the Hardy-Littlewood-Sobolev inequality, $(-\Delta)^s$ is the nonlocal fractional Laplacian operator with $s\in (0,1)$, $\mu\gt 0$ is a parameter and $\lambda$ appears as Lagrange multiplier. We show the existence of at least two distinct solutions in the presence of the mass-subcritical perturbation $\mu |u|^{p-2}u$ with $2\gt p\gt 2+\frac{4s}{N}$ under some assumptions on $\tau$.
Access status: Open Access ,
On a fixed point theorem for operator systems and eigenvalue criteria for existence of positive solutions
(Wydawnictwa AGH, 2026) Fernández-Pardo, Laura M.; Rodríguez-López, Jorge
We provide an alternative approach, based on the Leray-Schauder fixed point index in cones, to a fixed point theorem for operator systems due to Precup. Our focus is on the case of operators whose components are entirely of compressive type. The abstract technique is applied to a system of second-order differential equations providing a coexistence positive solution by means of an eigenvalue type criterion.