183 research outputs found

    Controlling structural and functional features of photosynthetic antenna

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    In order to gain control over the assembly and functioning of photosynthetic antenna, we have developed methods to manipulate pigment composition of bacterial LH1 complexes via their reconstitution with modified bacteriochlorophylls or carotenoids, major photoactive cofactors of these antennae. In the present work we show how the reconstitution and pigment exchange approach is applied to control structural and functional parameters of LH1 and its subunits. The size of the subunits and the energy of the first excited singlet state can be controlled via the use of detergent while the thermodynamics of LH1 formation can be modified using carotenoids and/or a co-solvent. Carotenoids affect the efficiency of the intracomplex energy transfer, while the replacement of native bacteriochlorophyll a with its Ni-substituted analog allows one to control the excited state properties of LH1. These results show that LH1 is a very promising model system applicable for the design of bio-inspired device performing solar energy conversion

    Photochemical study of a new bimolecular photoinitiating system for vat photopolymerization 3D printing techniques under visible light

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    In this work, we presented a new bimolecular photoinitiating system based on 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives as visible photosensitizers of diphenyliodonium salt. Real-time FTIR and photo-DSC photopolymerization experiments with a cycloaliphatic epoxide and vinyl monomers showed surprisingly good reactivity of the bimolecular photoinitiating systems under UV-A, as well as under visible light sources. Steady-state photolysis, fluorescence experiments, theoretical calculations of molecular orbitals, and electrochemical analysis demonstrated photo-redox behavior as well as the ability to form initiating species via photo-reduction or photo-oxidation pathways, respectively. Therefore, the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives were also investigated as a type II free-radical photoinitiator with amine. It was confirmed that the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives, in combination with different types of additives, e.g., amine as a co-initiator or the presence of onium salt, can act as bimolecular photoinitiating systems for cationic, free-radical, and thiol-ene photopolymerization processes by hydrogen abstraction and/or electron transfer reactions stimulated by either near-UV or visible light irradiation. Finally, the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives were selected for 3D printing rapid prototyping experiments. Test objects were successfully printed using purely cationic photosensitive resin, created on a 3D printer with a visible LED light source

    The Inclusion of other-sex peers in peer networks and sense of peer integration in early adolescence : a two-wave longitudinal study

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    The main goal of the analysis presented in this paper is to examine the dynamics of including other-sex peers in the peer networks of early adolescents, aged 11 (at T1) and 13 (at T2), and the relationship between sex heterophily and changes in the sense of peer integration. The analysis was conducted using the Latent Difference Score (LDS) model with data from a representative nationwide longitudinal study in Poland (n = 5748). With reference to the dynamics related to the heterophilic process, the research confirmed that at the beginning of grade 5 of primary school, heterophily is still relatively rare, yet towards the end of early adolescence, there is a gradual shift, more strongly in girls, towards breaking through the strictly same-sex segregation and embarking on heterophilic relationships. Importantly, the LDS model-even when controlling for different measures of peer network—showed significant and positive (among both girls and boys) relations between establishing cross-sex relationships and the sense of peer integration. The results indicate that the appearance of the opposite sex in the peer network between grades 5 and 6 will improve the sense of peer integration. The findings are discussed in relation to results from other studies in the field

    Pierwotne guzy neuroendokrynne piersi, opis czterech przypadków

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    Breast neuroendocrine tumours are rare, accounting for up to 5% of all breasts tumours and approximately 1% of all neuroendocrine tumours. In most cases, breast neuroendocrine tumours are histologically and moderately well differentiated. Neuroendocrine breast tumours lack characteristic imaging patterns. The histopathological assessment of these tumours is difficult, and in most cases the correct diagnosis is made after proper examination of the postsurgical specimen.Guzy neuroendokrynne piersi są rzadkimi nowotworami, stanowią do 5 % guzów piersi i około 1% wszystkich guzów neuroendokrynnych. Większość zmian jest dobrze i umiarkowanie zróżnicowana, jednak  w badaniach obrazowych trudno wskazać cechy morfologiczne, które byłyby charakterystyczne dla tej grupy nowotworów. Ocena histopatologiczna również jest trudna i najczęściej właściwe rozpoznanie stawiane jest dopiero na podstawie materiału pooperacyjnego.

    PLA-Based Hybrid and Composite Electrospun Fibrous Scaffolds as Potential Materials for Tissue Engineering

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    The aim of the study was to manufacture poly(lactic acid)- (PLA-) based nanofibrous nonwovens that were modified using two types of modifiers, namely, gelatin- (GEL-) based nanofibres and carbon nanotubes (CNT). Hybrid nonwovens consisting of PLA and GEL nanofibres (PLA/GEL), as well as CNT-modified PLA nanofibres with GEL nanofibres (PLA + CNT/GEL), in the form of mats, were manufactured using concurrent-electrospinning technique (co-ES). The ability of such hybrid structures as potential scaffolds for tissue engineering was studied. Both types of hybrid samples and one-component PLA and CNTs-modified PLA mats were investigated using scanning electron microscopy (SEM), water contact angle measurements, and biological and mechanical tests. The morphology, microstructure, and selected properties of the materials were analyzed. Biocompatibility and bioactivity in contact with normal human osteoblasts (NHOst) were studied. The coelectrospun PLA and GEL nanofibres retained their structures in hybrid samples. Both types of hybrid nonwovens were not cytotoxic and showed better osteoinductivity in comparison to scaffolds made from pure PLA. These samples also showed significantly reduced hydrophobicity compared to one-component PLA nonwovens. The CNT-contained PLA nanofibres improved mechanical properties of hybrid samples and such a 3D system appears to be interesting for potential application as a tissue engineering scaffold

    Changes in the morphological, rheological, and biochemical blood indicators in triathletes

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    The aim of this study was to assess how the influence of intense physical effort changes the morphological, rheological, and biochemical blood indicators in triathletes. The study group comprised 10 triathletes aged 30-45 years, members of the Active Side of Life Association (Kraków, Poland). Venous blood was collected from the study participants twice, before and after the DiablakBeskid Extreme Triathlon 2016 (the Carpathians, Poland), and once from the control group for analysis of the selected blood indicators. Statistically significant changes were observed in the study group before and after the triathlon in morphological blood indicators, in the elongation index at the shear stress of 0.30 and 0.58 Pa, in levels of electrolytes, creatinine (mmol/l), serum protein parameters, and high-sensitivity troponin (ng/l). No such differences were reported for the remaining parameters. In turn, when comparing the study group before the triathlon with the control group, statistically significant differences were recorded in MCHC (g/dl), in the elongation index at the shear stress of 0.30 and 0.58 Pa, and Cl– (mmol/l) levels. No such differences were reported for the remaining parameters. Blood haematological and biochemical indicators in individuals that participate in triathlons characterize the actual range and direction of effort-related changes well and allow for the diagnosis of transient adaptive effects. Rheological parameters, involving the evaluation of erythrocyte deformability and aggregation, are useful for monitoring the particularly undesirable, short- and long-term effects of practicing extreme sports such as triathlons
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