Controlling structural and functional features of photosynthetic antenna

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

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

Ultrasound-assisted dispersive micro-solid phase extraction using molybdenum disulfide supported on reduced graphene oxide for energy dispersive X-ray fluorescence spectrometric determination of chromium species in water

Molybdenum disulfide (MoS2) was supported on graphene oxide (GO) by hydrothermal method. The resulting nanocomposite (MoS2-rGO) was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The experiments show that at pH 2, MoS2-rGO has a great affinity for adsorption of hexavalent chromium ions while Cr(III) ions remain in aqueous sample. In the adsorption process, the dominant role plays chemisorption. The determined adsorption capacity is 583.5 mg g−1. Parameters affecting the extraction process, namely sample pH, sample volume, contact time, and matrix ions, were investigated by sequential batch tests. Under optimal conditions (pH 2, sample volume 50 mL, sonication time 10 min, adsorbent mass 1 mg), the calibration curve covers the 1–200 ng mL−1 range with a correlation coefficient (R2) of 0.998. The recovery of the method is 97 ± 3%. Other data of merit include a relative standard deviation of < 3.5%, enrichment factor of 3350, and detection limit of 0.050 ng mL−1. The accuracy of the method was confirmed by analysis of the reference materials QC1453 (chromium VI in drinking water) and QC3015 (chromium VI in seawater). The method was successfully applied to chromium speciation in water samples, including high salinity ones. The concentration of Cr(III) was calculated as the difference between the total concentration of chromium (after oxidation of Cr(III) to Cr(VI) with potassium permanganate) and the initial Cr(VI) content

Study of phase transition in Bi3TiNbO9-BaBi2Nb2O9 ceramics

The subject of the paper is lead free bismuth layer structure oxides (1-x)Bi3TiNbO9-xBaBi2Nb2O9 (x=0; 1; 2; 3 mol). The influence of Bi3TiNbO9-xBaBi2Nb2O9 ratio on dielectric and structural properties was studied in a wide range of temperatures. Change in the ratio causes a decrease in the maximum value of dielectric permittivity and shifts the temperature of 'max to low values, leading to linear decreasing of average grain size and linear increasing of ceramics density. These results indicate an augment of the packing degree and the participation of pores are significantly decreased with the increase of BaBi2Nb2O9 compound intake. Moreover, for 0.7Bi3TiNbO9-0.3BaBi2Nb2O9 ceramics the dielectric phase transition is broadened and the properties characteristic for the ferroelectric relaxor appear

Pierwotne guzy neuroendokrynne piersi, opis czterech przypadków

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.