Publications

Gain-layer degradation from exposure to radiation limits the use of Low-Gain Avalanche Diodes (LGADs) in high energy particle physics detector experiments. Proper understanding of how the gain-layer is altered is not available on a defect level. Only measurements for materials with much lower effective doping concentrations are available. The direct study of the gain-layer is not possible with typical defect spectroscopy measurements like Thermally Stimulated Currents (TSC) and Deep-Level Transient Spectroscopy (DLTS). To combat this problem and gain a better understanding of the processes which degrade LGADs, the Gain-Layer Project was started. Within this project 19050 diodes were produced with various Boron, Phosphorus, Oxygen and Carbon concentrations. The material used is low-resistivity p-type Silicon. The effective doping concentrations are in the order of typical LGAD gain-layers. These diodes will serve the defect community in the coming years for various studies. This article introduces this project with detailed descriptions of the diodes, their flavours and their processing, and reports on results from I-V, C-V, SIMS and DLTS measurements on unirradiated diodes.

Graphene oxide (GO) provides a versatile platform for the development of antimicrobial and anti-adhesive materials, particularly when combined with covalently immobilized bioactive compounds but translating antibiotic activity into a stable layer without clinically relevant drug leaching remains challenging. Here, we report a covalently engineered GO-moxifloxacin (GO-MOX) composite obtained by grafting MOX onto ethylenediaminefunctionalized GO via carbodiimide coupling. The successful functionalization was supported by complementary physicochemical analyses, including FTIR, NMR, Raman, XPS, TGA, SEM/EDS and XRD. TGA indicated a high MOX loading of approximately 44.75 wt%, while HPLC analysis revealed that extractable/free MOX represented only 0.0586% of the total MOX content, supporting the predominantly covalent and minimally releasing character of the material. GO-MOX showed pronounced antimicrobial activity against representative ESKAPEE pathogens, with MIC values of 7.81 & micro;g/mL against E. coli and 62.5 & micro;g/mL against the tested Gram-positive strains. In the antimycobacterial assay, GO-MOX markedly inhibited the growth of both drug-susceptible and rifampicin/isoniazid-resistant Mycobacterium tuberculosis strains under the tested conditions. Anti-adherence activity was observed at sub-inhibitory concentrations, with MBEC values of 1.95 & micro;g/mL for E. coli and 7.81 & micro;g/mL for S. aureus, suggesting interference with early bacterial attachment. Additional analyses on mature biofilms formed on titanium substrates showed that GO-based treatments, particularly GO-MOX, affected biofilm viability, promoted membrane permeabilization, and altered extracellular matrix components, including extra-cellular proteins, nucleic acids/eDNA-like fractions and polysaccharides. In vitro cellular assays showed that normal MRC-5 fibroblasts recovered metabolic activity to >= 80% after 72 h, whereas A549 cells displayed a concentration-and time-dependent decrease in viability. ROS generation and Caspase-3 activity further suggested that the selective antiproliferative response observed in A549 cells may be associated, at least in part, with oxidative stress-mediated apoptotic mechanisms. In silico target prediction and structural inspection of MOX-topoisomerase complexes suggested that GO-MOX may retain a MOX-related contribution involving bacterial DNA gyrase/topoisomerase IV, while GO may provide additional contact-associated interfacial effects. Overall, GO-MOX emerges as a promising antimicrobial and anti-adhesive nanoplatform with cell-selective antiproliferative effects, supporting its further investigation for the future development of biomedical antimicrobial surfaces and coatings.

This study explores the synthesis and characterization of a novel cationic porous organic polymer (cPOP, referred to as POP1) designed as an active material for electrochemical detection of chloramphenicol (CAP) in complex matrices. Unlike conventional sensing platforms, POP1 provides a high density of accessible adsorption sites and tailored chemical functionality, enabling selective host-guest interactions with CAP and improving sensing performance. The polymer was comprehensively characterized using scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), infrared (IR) and Raman spectroscopy and thermogravimetric analysis (TGDTA). The interaction between POP1 and CAP was investigated by isothermal titration calorimetry (ITC), revealing a spontaneous and enthalpy-driven adsorption process that underpins the sensing response. POP1 was incorporated into a chitosan matrix and deposited onto carbon screen-printed electrodes (C-SPE) to fabricate a robust and reproducible electrochemical sensor for CAP. Under optimized conditions, the sensor exhibited a sensitivity of 48 nA mu M- 1, a limit of detection of 1.67 mu M, and a limit of quantification of 5 mu M, along with good repeatability, selectivity, and operational stability over 30 days. Method validation was carried out using pharmaceutical products (topical suspensions, topical gels, injectable suspension, and eye drops) and animal biological samples (cow milk, cow urine and pig urine) containing CAP, yielding satisfactory analytical performance despite the complexity of the matrices and confirming the applicability of the proposed platform for real-sample analysis. These results demonstrate the potential of POPs as effective electrode modifiers for electrochemical sensors.

Cobalt triantimonide (CoSb3) skutterudites are canonical thermoelectric materials with significant potential for energy conversion. However, realizing their full potential depends on identifying and overcoming challenges related to their intrinsic properties and synthesis. This summary examines research efforts and advancements in CoSb3 and related compounds, with particular emphasis on their applicative potential since 2022. First, a concise evaluation of advancements in materials properties is conducted, including synthesis techniques and strategies to optimize the thermoelectric figure of merit. Next, a summary of recent advancements in thermoelectric devices based on CoSb3 skutterudites is presented, covering fabrication aspects, including the structural materials used, joining methods, and device performance. In conclusion, the current limitations of high-performance CoSb3based thermoelectric generators are identified, and future research directions are outlined, as they are essential to advancing this field.

Proper functioning and reliability of future fusion tokamaks, including ITER, will heavily depend on the capacity to exhaust extreme heat fluxes. Tungsten (W)-based monoblocks constitute a critical core structural component. These are made of copper-chromium-zirconium (CuCrZr) cooling ducts which are joined to W using a copper (Cu) interlayer. These monoblocks must ensure efficient heat exhaustion while preserving the structural integrity under extreme operating conditions. The characterization and modelling of the interface cracking resistance of W/Cu joints is key. A single parameter interface toughness is not rich enough to encompass a wide range of stress states, especially when plasticity develops in one of the adjoining materials. The goal of this work is to develop a robust methodology to determine interface toughness and an approach to transfer data from small scale specimens to real components. A combined methodology using miniaturized three-point bending specimens and cohesive zone modelling was developed and validated, first, at room temperature. Bimaterial specimens with a notch are tested, exhibiting a ductile mode fracture with dimples on the Cu side, which suggests good delamination resistance of W/Cu joints. Cracking is accompanied by plastic dissipation. The peak strength and interface energy cohesive zone parameters are identified providing excellent correspondence between simulated and experimental load-displacement curves. Validation is made by comparing plastic zone sizes and by connecting the values to a micromechanical analysis.

This work presents a comprehensive investigation of the structural, microstructural, magnetic, and magneto-caloric properties of La0.9-xPbxNa0.1MnO3 (x = 0 and 0.1), synthesized through a flash combustion technique and subsequently pressed into pellets. Structural analysis confirms that both samples crystallize in a rhombohedral structure without detectable secondary phases or impurities. Microstructural observations reveal a homogeneous morphology in both compositions, with a noticeable grain growth effect induced by Pb doping. Magnetic measurements show a clear paramagnetic-ferromagnetic phase transition in both samples. The Curie temperature shifts from 179 K for the undoped compound to 309 K for the Pb-doped compounds. Furthermore, the magnetic entropy change and the relative cooling power increase from 3.01 J/kg.K and 184.72 J/kg for La0.9Na0.1MnO3 to 4.56 J/kg.K and 291.29 J/kg for La0.8Pb0.1Na0.1MnO3. Together, these results highlight the beneficial effect of Pb doping in the studied system for room-temperature magnetic refrigeration applications.

Structural and electronic transport features of high quality epitaxial metastable fcc W and beta-W2N thin films compatible with spintronic multilayer nanosystems are reported in a parallel approach. The epitaxial layers have been successfully prepared in a broad range of thicknesses from a few to tens of nanometers. The scalable method of auxiliary plasma assisted substrate magnetron sputtering was used. The epitaxy relationship between the thin films and MgO (100) single-crystal substrate is highlighted by high resolution XRD investigations of the reciprocal space. Electron transport properties are discussed with respect to the striking behavior observed via resistivity over temperature cycles. The chemical stability as active buffer layers of both fcc W and beta-W2N thin films is shown in spintronic configurations, where a thin film of Fe is interposed between W or W2N layers. The reported results show that the obtained high quality W based epitaxial layers are superior template-matched buffers for epitaxial Fe layers, enabling a new class of functional spintronic heterostructures.

This study investigates the effect of synthesis parameters on the catalytic performance of Mo-Ti oxide materials in the esterification of levulinic acid (LA) with various alcohols. Three sol-gel synthesis strategies were used for the catalyst's preparation, without additives, using malic acid as complexing agent and polyethylene glycol as surfactant and templating agent. The samples were characterized by structural and surface-sensitive techniques. Detailed kinetic investigations were conducted for the esterification of LA with butanol, assessing the effect of temperature, alcohol-to-acid molar ratio, catalyst loading and activation energy. Catalysts prepared in the absence of any additives or in the presence of a templating agent exhibit comparable activities, both exceeding that of the catalyst obtained with a complexing agent. This behavior is consistent with the smaller Mo6+/Mo5+ surface ratio and with the greater density of acid sites per unit surface area. Our results highlight the critical importance of synthesis strategy in tuning the surface composition and acidity of Mo-Ti catalysts for biomass-derived molecule conversion.

We study the eigenspectrum properties of a one-dimensional molecular chain composed of hexagonal unit cells. The system features two alternating hopping parameters, resulting in a rich energy spectrum with both dispersive and flat bands. By analyzing the model under periodic and open boundary conditions, we identify two insulating phases separated by a gap-closing transition controlled by the ratio of hopping amplitudes. In the topological phase, realized when the hopping ratio falls below a critical value, edge states emerge that are exponentially localized at the boundaries of finite chains.

Multilayer oxide/metal/oxide (OMO) structures emerge as suitable alternative to indium tin oxide (ITO) in transparent conductive electrode (TCE) field mainly due to their high visible light transmittance and low resistivity. Moreover, OMO structures are appropriate for flexible organic optoelectronic devices being less susceptible to cracking than single-layer ITO electrodes. Therefore, the present study is focused on the assessment of the properties of ZnO/Ag/ZnO (ZAZ) structures deposited by consecutive radio frequency magnetron sputtering (ZnO) and thermal vacuum evaporation (Ag) on flexible substrates such as polyethylene terephthalate, polyethersulfone and flexible glass. Additionally, the ZAZ deposition was carried out on patterned polyethersulfone in order to evaluate the nanopatterning effect on the properties of the multilayer structures. For comparison, ZAZ structures were also deposited on rigid glass substrate, this being commonly used in optoelectronic devices. The optical and electrical measurements reveal that the roughness of the deposition substrate has a significant impact on the transmittance and sheet resistance of the ZAZ multilayers. Thus, the best performance in terms of transmittance at 550 nm wavelength (82.7%), sheet resistance (9.5 52/square) and figure of merit (15.75x10-3 52-1), correlated with the lowest roughness (2.3 nm), is achieved for the structure fabricated on flexible glass. The values of the TCE key parameters endorse the developed ZAZ structures for optoelectronic applications.