Polish Academy of Sciences
Recent publications
Refractive index engineering is a key element in the design of optoelectronic device structures. In this work we present a method for the fabrication of buried hollow channels, periodically arranged inside GaN structures. The method is based on selective area doping and electrochemical etching. Channels width is defined by the selective area ion implantation mask geometry while the channel vertical dimension depends on the implantation energy and annealing conditions. In this work we used implantation with Si 100 keV and dose 2.6·10¹⁵ cm⁻² into GaN. Next, a 100 nm GaN layer was grown by plasma-assisted molecular beam epitaxy (PAMBE). After annealing at 1070 °C for 5 min, selectively doped regions were removed in the process of electrochemical etching (ECE), forming periodically arranged empty volumes. Annealing resulted in partial strain removal as observed by X-Ray diffraction. Surface roughness was evaluated at every stage of the process: after implantation, after regrowth and after annealing, and it is promising for the integration of the proposed technology with device fabrication and processing. The flexibility in the mask design for selective ion implantation and a high refractive index contrast between GaN and air, make the proposed technology attractive for the fabrication of buried photonic structures such as diffraction gratings.
In this paper, we investigate the alliance strategy in an Online Retailing Supply Chain (ORSC). Three alliance models in addition to one no alliance model are built and examined. The no alliance model as a benchmark is developed to characterize the alliance motivation for each supply chain member. Afterwards, we identify the optimal alliance strategy and the final alliance equilibrium. The results show that the manufacturer always has motivations to form an alliance with each of other two members, while the retailer and the platform may form an alliance only when the agency rate is relatively low. Moreover, under certain conditions, all supply chain members could achieve a win-win-win result in the manufacturer-retailer and manufacturer-platform alliance models, but fall into a lose-lose-lose situation in the retailer-platform alliance model. Additionally, it is interesting that a higher agency rate makes the retailer more profitable when the platform and manufacturer enter into an alliance. Finally, we find that each of the three alliance models may be the final equilibrium, which is largely dependent on channel competition and the agency rate.
Soil fungal communities are critical components in soil ecosystems, but experimental researches on their responses to the silver birch succession are limited. Arbuscular mycorrhizal (AM) fungi and glomalin-related soil protein (GRSP) – a type of glycoprotein produced by hyphae of AM fungi, are highly correlated with soil physicochemical parameters and are sensitive to changes in the soil environment. This study aimed to analyze the dynamics of a soil fungal community, with particular emphasis on the AM fungi and GRSP contents and their responses to a silver birch succession on abandoned post-arable land. The studies were conducted in central Poland and covered five stands that included arable field (AF) and fallow (FA) land, and 8-year-old/young (YS), 33-year-old/middle (MS), and 40-year-old/old (OS) successions of silver birch. The diversity and compositions of the fungal communities were examined using ITS high-throughput gene sequencing. We found that the dominant soil fungal phylum transitioned from Olpidiomycota through Ascomycota to Basidiomycota with the change from AF to OS. Silver birch development increased the soil fungal diversity and richness compared with that of the AF soil, but these decreased compared with the FA soil. The predominant fungi in the soils under silver birch development belonged to the families Pezizaceae, Russulaceae, and Cortinariceae. The birch succession significantly decreased the abundance of potential pathotrophs and increased the relative abundance of symbiotrophic fungi. The AM fungi abundance varied across the successional stages and was affected by plant cover and N content, and positively correlated with the EE-GRSP and T-GRSP contents. Additionally, the EE-GRSP and T-GRSP contents positively correlated with the TOC, N and SOM content, and Tp, and negatively correlated with Bd. Across the successional stages, the YS was devoid of AM fungi and characterized by the lowest EE-GRSP T-GRSP (1.89 mg g⁻¹), Tp (43.4%), and TOC (7.3 g kg⁻¹) and P (11.7 g kg⁻¹) contents. In summary, the development of young silver birch on generally poor Brunic Arenosols tends to have a negative effect on the soil fungal community and selected soil properties, but these effects ease over time.
The objective of the study was to analyze the effect of the pyrolysis temperature (PT) and feedstock on the quality and quantity of humic-like (HLAs) and fulvic-like (FLAs) acids entrapped in the biochars (BioCs) produced from leaves, litter, and straw of forest habitat at different temperatures. Extraction methods, 3DEEM fluorescence and UV–vis spectroscopies enabled to track the changes of HLAs and FLAs concentration, humification degree, lignin type compounds, biological index, aromaticity/aliphaticity, molecular weight and quality of fluorophores. Additionally, the feedstock and PT effect was discussed for the properties of the BioCs and the water extractable organic matter (WEOM). The results showed that the PT increase caused increase in the pH, ash, surface area and negative charge of the BioCs. Woody feedstock resulted in the BioCs with lower ash content, while the BioCs derived from straw revealed low content of organic matter and carbon but high surface area. The feedstock effect was not clear on structural parameters of HLAs and FLAs, however the BioC derived from litter at 750 °C placed HLAs in group of the strong humification. Woody parts in feedstock and increasing PT was the reason of lower humic-like substances content. It was relatively high after pyrolysis at 430 °C and decreased rapidly at higher PTs. The PT increase affected structure of organic fractions. For HLAs, thermal transformation lead to increase of the humification, molecular weight and content of aromatic structures. Changes for FLAs revealed opposite trend due to a greater susceptibility to the pyrolytic partitioning of molecules. PT elevation resulted also in decreasing contribution of protein- and aminoacid- like compounds and degradation of structures derived from lignin-rich feedstocks. These changes were accompanied by progressive decrease in the biological index of HLAs revealing gradual destruction of freshly produced compounds of microbiological origin. WEOM was enriched in organic compounds typical for HLAs fraction, and PT effect was similar to this predominant fraction.
Self-diffusion of Ti in HCP HfTiZr and AlScHfTiZr multi-principal element alloys is measured using the radiotracer technique and applying the ⁴⁴Ti isotope. In the temperature interval from 973 K to 1373 K, no systematic deviations from linear Arrhenius temperature dependencies are observed. Alloying equiatomic HfTiZr with Al and Sc enhances Ti diffusion rates and the effect becomes more pronounced with increasing Al content. The Ti diffusivities in the present multi-principal element alloys are found to exceed the values predicted by a simple geometric mean of the Ti diffusion coefficients in the pure metals by orders of magnitude, a phenomenon which we refer to as ‘anti-sluggish’ diffusion. Lattice distortions are speculated to dominate the relative enhancement of Ti diffusion in these HCP high-entropy alloys, inducing the ‘anti-sluggish’ behavior. The experimental findings are supported by ab initio-derived mean squared atomic displacements and potential energy fluctuations in these alloys.
The Oligocene Menilite Beds are considered the most important source rock for hydrocarbon accumulation in the Polish Carpathian region, whereas the Cretaceous Lgota Beds have been regarded as an additional potential source rock. Understanding their petrophysical and geochemical properties is essential for evaluating the hydrocarbon potential of these beds. This paper presents mineral and organic porosity characterization and focuses on factors responsible for the development of organic pores as a reflection of the depositional and diagenetic processes. Mudstones were evaluated as potential source and reservoir rocks, describing their diagenetic and thermal history and examining their effective porosity and permeability. The results show that the Lgota Beds mudstone in the Huczwice quarry is thermally mature (late oil/early gas window, Tmax 460–470 °C), containing type III kerogen and TOC between 0.68 wt% and 4.2 wt%, in contrast to the Menilite Beds mudstone (Monasterzec outcrop), which is thermally immature (Tmax<426 °C), containing type II kerogen and TOC content from 1.24 wt% to 8.7 wt%. The geochemical properties show that the Lgota mudstone is currently an ineffective source rock, whereas the Menilite mudstone can be a potential source rock. SEM-identified pores include mineral pores, organic pores and microfractures. Organic porosity is observable both in immature oil-prone type II kerogen and highly mature gas-prone type III kerogen. The amount of pores in organic matter increases with maturity, and no relation between TOC and organic porosity development has been observed. Palynofacies analysis showed that the Menilite and Lgota mudstones are dominated by amorphous organic matter, and that the Lgota mudstone also contains opaque woody material. MICP measurements indicate high (up to 15%) effective porosity values for the Menilite Beds and up to 8% for the Lgota Beds, with very low permeability values (<0.1 mD) in both cases. Isotherms obtained from nitrogen adsorption are type IV for the Lgota Beds and type II for the Menilite Beds, while the BET surface areas are around 13 m²/g and 3 m²/g, respectively. The Lgota Beds demonstrate advanced diagenetic processes such as compaction, cementation, dissolution, replacement, and transformation, which contributed to the significant reduction in porosity, while the Menilite Beds represent an early stage of burial with the prevailing impact of compaction and thus less destruction of original pores. Finally, the Menilite Beds from the Monasterzec outcrop do not demonstrate sufficient conditions for shale-oil/-gas source rock due to the lack of proper thermal maturity. Such criterion is fulfilled by the Lgota Beds in the Huczwice quarry, but due to very low hydrocarbon potential, the Lgota mudstone is an ineffective source rock. However, given the other petrophysical and geochemical properties, the analysed formations may constitute a basis for further research on the occurrence of unconventional reservoirs in the entire Carpathian region.
Objective Neoadjuvant chemotherapy (NAC) in breast cancer requires non-invasive methods of monitoring its effects after each dose of drug therapy. The aim is to isolate responding and non-responding tumors prior to surgery in order to increase patient safety and select the optimal medical follow-up. Methods A new method of monitoring NAC therapy has been proposed. The method is based on image quality indexes (IQI) calculated from ultrasound data obtained from breast tumors and surrounding tissue. Four different tissue regions from the preliminary set of 38 tumors and three data pre-processing techniques are considered. Postoperative histopathology results were used as a benchmark in evaluating the effectiveness of the IQI classification. Results Out of ten parameters considered, the best results were obtained for the Gray Relational Coefficient. Responding and non-responding tumors were predicted after the first dose of NAC with an area under the receiver operating characteristics curve of 0.88 and 0.75, respectively. When considering subsequent doses of NAC, other IQI parameters also proved usefulness in evaluating NAC therapy. Conclusions The image quality parameters derived from the ultrasound data are well suited for assessing the effects of NAC therapy, in particular on breast tumors.
This paper aims to find the reasons why some citation models can predict a set of specific bibliometric indices extremely well. We show why fitting a model that preserves the total sum of a vector can be beneficial in the case of heavy-tailed data that are frequently observed in informetrics and similar disciplines. Based on this observation, we introduce the reparameterised versions of the discrete generalised beta distribution (DGBD) and power law models that preserve the total sum of elements in a citation vector and, as a byproduct, they enjoy much better predictive power when predicting many bibliometric indices as well as partial cumulative sums. This also results in the underlying model parameters’ being easier to fit numerically. Moreover, they are also more interpretable. Namely, just like in our recently-introduced 3DSI (three dimensions of scientific impact) model, we have a clear distinction between the coefficients determining the total productivity (size), total impact (sum), and those that affect the shape of the resulting theoretical curve.
Arabinogalactan proteins (AGPs) are constituents of the plant cell walls, which are increasingly being considered as essential molecules in the formation of the extracellular matrix. Given their molecular structure and the advantage of the carbohydrate moiety, the glycosylation level and its modification is assumed as a cause of the functional diversity of AGPs. The aim of current work was to evaluate the molecular features of AGP as a potential molecule involved in the ripening process. For this purpose, tomato fruits were analyzed at specific five stages of ripening using microscopic and molecular tools. The experiment showed that the high content and the occurrence of the AGP molecule with molecular weight around 120 kDa are related to cell wall conditions and the intensity of ongoing glycosylation. At the breaker and/or turning stage, the processes of modification of the sugar moiety and depolymerization begin to prevail. At the red ripe/pink stage, the synthesis process is replaced by the degradation process, which is associated with the disappearance of AGPs with high molecular weights and the appearance of only single sugar residues with very low molecular weights. The occurrence of AGPs with low molecular weight (∼30 kDa) may be used as a marker of the finalization of the ripening process in tomato fruits. All anatomical and morphological alterations in the cell wall confirm the presence of dependencies and connections between components of the cell wall network. We may presume that selected antibodies (JIM13, LM2, LM14) indicate very specific features of the fruit tissue at different stages of ripening; thus, AGP is a molecular and cytological marker of particular stages of the fruit ripening process.
The work aimed at the development of benign solid base catalysts as alternatives for presently used noxious liquid bases. Talc, possessing intrinsic basic properties, was chosen as a particularly attractive and cost-effective precursor. Activation of talc by grinding in a planetary mill followed by treatment with 2 M NaOH was employed as means for basicity enhancement. Such protocol enabled profound modification of talc structure, otherwise resistant to treatment with a basic solution. Deep changes, not addressed in the literature reports so far, took place in the course of combined mechanical and alkali treatment. The amorphized ground talc transformed to the magnesium silicate hydrate (MSH) phase and brucite. Treatment with NaOH led to significant enhancement of surface basicity with respect to the parent materials. The effect was particularly spectacular for alkali-treated, strongly ground talc samples, containing the MSH component. The materials were tested in a base-catalyzed reaction of aldol condensation of acetone. The trend of catalytic activity followed closely the order of surface basicity, which pointed to the key role of MSH as a catalytically active phase in the modified talc solids. Joint mechanical and alkali activation of talc proved to be a simple, yet promising way of developing solid base materials for catalytic applications.
This research demonstrates the use of genetic algorithms for damage detection in isotropic rods. The spectral element method and a deep-learning-based surrogate model is utilized for simulating wave propagation in an isotropic cracked rod. The genetic algorithm employs results (“numerical experiment") obtained from the spectral element model and the deep-learning-based surrogate to determine the optimized crack locations and crack depths as output parameters. The objective function used in the genetic algorithm is the mean square error between the response obtained from spectral element model and the deep-learning-based surrogate model.
Wave propagation in structures is generally computed by numerical methods such as finite element method, spectral element method, etc. In these numerical methods, spatio-temporal discretization of the partial differential equations is performed using a fine mesh which leads to high computation cost but precise results. A trade-off between accuracy and computational cost can be achieved by adopting deep learning-based approaches. This research demonstrates an alternative deep learning-based approach for predictive modeling of wave propagation signals within damaged structural elements. Our goal is to evaluate the wave propagation spatio-temporal solution matrix for a given crack depth and crack location within the structural element. In this framework, deep-learning-based surrogate modeling is proposed by utilizing a deep convolutional autoencoder (DCAE) to learn the wavefield representation and project it to a compressed domain called latent space. This latent space works as labels for a feed-forward neural network (FFNN) followed by DCAE. This process eliminates the need to solve the system’s governing equations each time, leading to significant savings in computational costs and making the method excellent for issues that require repeated model computations. In DCAE architecture, we integrated the squeeze-and-excitation (SE) block which works as a channel-wise attention mechanism and enhanced the performance of the model. The DCAE with SE block achieved the very good reconstruction accuracy. This deep learning-based wave propagation predictive model can be a valuable resource for generating data for a given crack depth and location, which can be used for inverse formulations and various structural health monitoring (SHM) application.
In this work, inspired by the interpretability and usefulness of the statistical process control, we propose a novel procedure for simultaneous monitoring of multiple processes that is based on a neural network with learnable activation functions. The proposed procedure for learning control limits with neural network (CONNF) is aimed at scenarios where labeled data are available and makes use of these labels. CONNF can be particularly useful in monitoring processes when the amount of run-in data is insufficient, or the cost of obtaining such data is high. We illustrate the performance of CONNF method with a simulation study and preliminary results for real-life data collected from smartphones of patients with diagnosed bipolar disorder. These results show the potential of CONNF and indicate further research directions.
We present the spontaneous growth of self-assembled epitaxial nanostructures of BiFeO3 (BFO) obtained by Pulsed Laser Deposition. The BFO phase architectures of squares, stripes and pyramids were grown on (0 0 1), (1 1 0) and (1 1 1) SrTiO3 (STO) substrates, respectively. The morphology of the BFO nanostructures was determined by Scanning Electron Microscopy and Atomic Force Microscopy revealing their vertical alignment and self-assembled feature on the surface of the entire substrate. Structural analysis was made along in-plane and out-of-plane directions employing X-ray Diffraction. We determined the growth routes of BFO nanostructures and established a relationship between their morphology and structural properties. Such self-ordered crystalline nanostructures could be used as a tailored platform for the deposition of the ferromagnetic phase, thus providing an alternative method for the fabrication of BFO-based multiferroic vertically aligned nanocomposites.
Tardigrada is an invertebrate phylum that often constitutes a dominant micrometazoan group on glaciers worldwide. We investigated tardigrades residing in surface ice above the equilibrium line altitude (ELA) on three temperate glaciers of New Zealand’s Southern Alps. Morphological, morphometric and multilocus DNA analyses (CO1, 18S rRNA, 28S rRNA, ITS-2) revealed two new genera comprising four species, of which two are formally described here: Kopakaius gen. nov. nicolae sp. nov. and Kararehius gen. nov. gregorii sp. nov. The former is represented by three genetically distinct phyletic lineages akin to species. According to CO1, Kopakaius gen. nov. nicolae sp. nov. inhabits Whataroa Glacier only while the remaining two Kopakaius species occur on Fox and Franz Joseph Glaciers, suggesting low dispersal capabilities. Although morphological characteristics of the new genera could indicate affinity with the subfamily Itaquasconinae, phylogenetic analysis placed them confidently in the subfamily Diphasconinae. Kopakaius gen. nov. lack placoids in the pharynx similar with some Itaquasconinae, whereas dark pigmentation and claw shape aligns them with the glacier-obligate genus, Cryobiotus (subfamily Hypsibiinae), which is an example of parallel evolution. The second genus, Kararehius gen nov. could be classified as Adropion-like (subfamily Itaquasconinae), but differs greatly by genetics (placed in the subfamily Diphasconinae) as well as morphology (e.g., lack of septulum), exemplify deep stasis in Hypsibiidae. Our results suggest that glacier fragmentation during the Pleistocene triggered tardigrade speciation, making it a suitable model for studies on allopatric divergence in glacier meiofauna.
This paper reports on the possibility of applying carbon nanotubes as an additive to metallic materials, where a new phase forms in situ from the powder mixture. Multi-walled carbon nanotubes (MWCNT) amounts of 1 vol% and 3 vol% were applied to synthesize a composite with interpenetrating phases obtained from magnesium microsized powder and nanosized silicon (n)Si by sintering under vacuum. In the experiments, two ordered Mg-(n)Si-MWCNT powder mixtures with a (n)Si: MWCNT ratio of 2: 1 were prepared by sonication. The effects of Mg2Si silicide in situ synthesis on the behavior of MWCNTs and the Mg2Si and Mgα morphology were studied. Using LM with quantitative metallography, SEM with EDS, XRD, HREM, it was found that the MWCNTs were a component of the skeleton formed by submicron and nanosized Mg2Si, MgO, and Mgα mixture. Non-agglomerated MWCNTs were also found in microsized Mg2Si particles in the composite. A decrease in the silicide crystallite size was also observed compared with material without a carbon nanocomponent. The transformation of MWCNTs into another phase or their morphology change was not observed. Therefore, the effects described in this paper can be adapted to technologies focused on different types of composites and for designing Mg2Si-based thermoelectric materials and intermetallic alloys.
We study from first principles the magnetic, electronic, orbital and structural properties of the LaMnO3 doped with gallium replacing the Mn-site. The gallium doping reduces the Jahn–Teller effect, and consequently the bandgap. Surprisingly, the system does not go towards a metallic phase because of the Mn-bandwidth reduction. The Ga-doping tends to reduce the orbital order typical of bulk antiferromagnetic LaMnO3 and consequently weakens the antiferromagnetic phase. The Ga-doping favors the G-type orbital order and layered-ordered ferromagnetic perovskite at x=0.50, both effects contribute to the formation of the insulating ferromagnetic phase in LaMn1−xGaxO3.
The set of six fluorophosphate glasses were obtained to measure the effect of composition on their thermal and luminescence properties. It was found that the phosphate network can accept much more lithium fluoride as compared to silica and borate glasses. The differential thermal analysis study shows a significant increase of thermal stability and decrease of the crystallization with higher content of lithium fluoride. Simultaneously, a gradual increase in the intensity of thermoluminescence was observed as well as linearity of the thermoluminescence response. We correlated the observed effects with the structural changes based on fourier-transform infrared spectroscopy and magic angle spinning nuclear magnetic resonance analysis.
Background The development of digital technologies and the evolution of open innovation approaches have enabled the creation of diverse virtual organizations and enterprises coordinating their activities primarily online. The open innovation platform titled “International Natural Product Sciences Taskforce” (INPST) was established in 2018, to bring together in collaborative environment individuals and organizations interested in natural product scientific research, and to empower their interactions by using digital communication tools. Methods In this work, we present a general overview of INPST activities and showcase the specific use of Twitter as a powerful networking tool that was used to host a one-week “2021 INPST Twitter Networking Event” (spanning from 31st May 2021 to 6th June 2021) based on the application of the Twitter hashtag #INPST. Results and Conclusion The use of this hashtag during the networking event period was analyzed with Symplur Signals (https://www.symplur.com/), revealing a total of 6,036 tweets, shared by 686 users, which generated a total of 65,004,773 impressions (views of the respective tweets). This networking event's achieved high visibility and participation rate showcases a convincing example of how this social media platform can be used as a highly effective tool to host virtual Twitter-based international biomedical research events.
Chronic pain is a persistent, complex condition that contributes to impaired mood, anxiety and emotional problems. Osteoarthritis (OA) is one of the major causes of chronic pain in adults and elderly people. A substantial body of evidence demonstrate that hippocampal neural circuits, especially monoamine dopamine and serotonin levels, contributes to negative affect and avoidance motivation experienced during pain. Current pharmacological strategies for OA patients are unsatisfying and the endocannabinoid system modulation might represent an alternative for the treatment of OA-related pain. In the present study, we used a rat model of osteoarthritis induced by intra-articular injection of sodium monoiodoacetate to assess, 28 days post-induction, the contribution of endocannabinoid system on the possible alteration in pain perception and affective behavior, in LTP and monoamine levels in the lateral entorhinal cortex-dentate gyrus pathway. The results show that OA-related chronic pain induces working memory impairment and depressive-like behavior appearance, diminishes LTP, decreases dopamine levels and increases serotonin levels in the rat dentate gyrus. URB597 administration (i.p., 1 mg/kg) reduces hyperalgesia and mechanical allodynia, improves recognition memory and depressive-live behavior, restores LTP and normalizes monoamine levels in the hippocampus. The effect was observed 60–120 min post-treatment and was blocked by AM251, which proves the action of URB597 via the CB1 receptor. Therefore, our study confirms the role of anandamide in OA-related chronic pain management at the behavioral and hippocampal levels. This article is part of the Special Issue on ‘Advances in mechanisms and therapeutic targets relevant to pain’.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
3,095 members
Sławomir Łotysz
  • Institute for the History of Science
Mateusz Piotr Nowak
  • Institute of Theoretical and Applied Informatics
Ryszard Ostaszewski
  • Institute of Organic Chemistry
Carmine Autieri
  • International Centre for Interfacing Magnetism and Superconductivity with Topological Matter – MagTop
Warsaw, Poland