Effect of Dehydrated Trehalose Matrix on the Kinetics of Forward Electron Transfer Reactions in Photosystem I

The effect of dehydration on the kinetics of forward electron transfer (ET) has been studied in cyanobacterial photosystem I (PS I) complexes in a trehalose glassy matrix by time-resolved optical and EPR spectroscopies in the 100 fs to 1 ms time domain. The kinetics of the flash-induced absorption changes in the subnanosecond time domain due to primary and secondary charge separation steps were monitored by pump–probe laser spectroscopy with 20-fs low-energy pump pulses centered at 720 nm. The back-reaction kinetics of P700 were measured by high-field time-resolved EPR spectroscopy and the forward kinetics of A∙−1A/A∙−1B→FX by time-resolved optical spectroscopy at 480 nm. The kinetics of the primary ET reactions to form the primary P∙+700A∙−0 and the secondary P∙+700A∙−1 ion radical pairs were not affected by dehydration in the trehalose matrix, while the yield of the P∙+700A∙−1 was decreased by ~20%. Forward ET from the phylloquinone molecules in the A∙−1A and A∙−1B sites to the iron–sulfur cluster FX slowed from ~220 ns and ~20 ns in solution to ~13 μs and ~80 ns, respectively. However, as shown by EPR spectroscopy, the ~15 μs kinetic phase also contains a small contribution from the recombination between A∙−1B and P∙+700. These data reveal that the initial ET reactions from P700 to secondary phylloquinone acceptors in the A- and B-branches of cofactors (A1A and A1B) remain unaffected whereas ET beyond A1A and A1B is slowed or prevented by constrained protein dynamics due to the dry trehalose glass matrix

Assessment of the impact of agricultural technologies on the fertility, health and stability of chernozem

This study aimed to comprehensively evaluate the effects of agricultural technologies on the quality, health, and stability of slightly eroded chernozem in grain crop rotation using the author's methodology. The research was conducted on the experimental field of the Kursk FANC from 2018 to 2021. Three agricultural technologies were tested: a traditional method with crushed by-products (PP), agrobiotechnology-1 (PP and microbiological preparations), and agrobiotechnology-2 (agrobiotechnology-1 + 10 kg a.i. N per 1 t of PP). The results showed that all technologies had a satisfactory impact on soil fertility, health, and stability, with most indicators remaining unchanged. Agrobiotechnology-1 had a good impact on soil fertility and stability and an excellent impact on soil health. Agrobiotechnology-2 had an excellent impact on soil, with significant and highly significant increases in most indicators. The comprehensive assessment indicated that agrobiotechnology-2 had the highest overall impact, with a Kcomp value of 21.4%

Femtosecond primary charge separation in Synechocystis sp. PCC 6803 photosystem I

AbstractThe ultrafast (<100fs) conversion of delocalized exciton into charge-separated state between the primary donor P700 (bleaching at 705nm) and the primary acceptor A0 (bleaching at 690nm) in photosystem I (PS I) complexes from Synechocystis sp. PCC 6803 was observed. The data were obtained by application of pump–probe technique with 20-fs low-energy pump pulses centered at 720nm. The earliest absorbance changes (close to zero delay) with a bleaching at 690nm are similar to the product of the absorption spectrum of PS I complex and the laser pulse spectrum, which represents the efficiency spectrum of the light absorption by PS I upon femtosecond excitation centered at 720nm. During the first ∼60fs the energy transfer from the chlorophyll (Chl) species bleaching at 690nm to the Chl bleaching at 705nm occurs, resulting in almost equal bleaching of the two forms with the formation of delocalized exciton between 690-nm and 705-nm Chls. Within the next ∼40fs the formation of a new broad band centered at ∼660nm (attributed to the appearance of Chl anion radical) is observed. This band decays with time constant simultaneously with an electron transfer to A1 (phylloquinone). The subtraction of kinetic difference absorption spectra of the closed (state P700+A0A1) PS I reaction center (RC) from that of the open (state P700A0A1) RC reveals the pure spectrum of the P700+A0− ion–radical pair. The experimental data were analyzed using a simple kinetic scheme: An* →k1 [(PA0)*A1→<100fs P+A0−A1] →k2P+A0A1−, and a global fitting procedure based on the singular value decomposition analysis. The calculated kinetics of transitions between intermediate states and their spectra were similar to the kinetics recorded at 694 and 705nm and the experimental spectra obtained by subtraction of the spectra of closed RCs from the spectra of open RCs. As a result, we found that the main events in RCs of PS I under our experimental conditions include very fast (<100fs) charge separation with the formation of the P700+A0−A1 state in approximately one half of the RCs, the ∼5-ps energy transfer from antenna Chl* to P700A0A1 in the remaining RCs, and ∼25-ps formation of the secondary radical pair P700+A0A1−

Iodine deficiency: socio-economic problems and new approaches to its solution in veterinary medicine

One of the global, vital problems of humanity is iodine deficiency. According to the World Health Organization (WHO), more than 2 billion people live in conditions of iodine deficiency. people: among them, 740 million have endemic goiter, 43 million have mental retardation, more than 6 million. they suffer from cretinism (an extreme degree of mental retardation). Currently, iodine deficiency diseases are the most common non-infectious diseases in the world. What about mammalian animals? In animals, iodine performs the same functions as in humans. Animals, especially agricultural animals, are just as sensitive to iodine deficiency as humans. With a lack of iodine in the body of animals, the biosynthesis of thyroid hormones is disrupted, which leads to a decrease in the intensity of redox processes, as a result of which all types of metabolism are disrupted:-protein, fat, carbohydrate, macro – and microelement, energy. In this regard, the failure of the thyroid gland is accompanied by the development of severe pathobiochemical processes, which, in the end, leads to the clinical manifestation of pathophysiological conditions. Taking into account the fact that in conditions of constant iodine deficiency it is very problematic to ensure the health of productive animals, the issues of prevention of iodine deficiency conditions are economically significant for industrial animal husbandry. It is no accident that in countries experiencing natural iodine deficiency, state programs have been developed that provide for the use of iodine-containing additives in the diets of productive animals. Despite the fact that the simplest and most affordable method of eliminating iodine deficiency in humans and animals is the inclusion of iodized salt in the diet, however, this method can not be used for veterinary purposes. First of all, the feed method of using biologically active additives eliminates the possibility of dosed therapeutic or preventive treatment. On the pages of this article, we draw attention to the emerging prospects for the use of a new iodine-metabolic composition in non-infectious and infectious pathology, based on an iodine polymer complex known in pharmacology as iodinol and succinic acid

An approach to automation of a rational choice of adaptive agricultural technologies

The research was conducted at the premises of the agricultural systems laboratory on the basis of research findings and analysis and generalization of modern scientific literature on a rational choice of adaptive technologies for cultivation of 10 crops (wheat, barley, rye, peas, millet, etc.) for different conditions in Russia. The most effective conditions for technologies application facilitating the efficient use of available resources were determined. Criteria, standards and requirements for the efficiency of the most important technological techniques of modern agricultural technologies were posed, as well as approaches to automation and an algorithm for their rational choice. The scheme and structure of the database of the agricultural producer support system for a rational choice of highly profitable adaptive technologies for leading grain crops cultivation were developed. The structure of the database of the decision support system is represented in three units: initial information, regulatory and reference information and calculation algorithms. The implementation of the developments into the production process opens up opportunities for the most efficient use of the existing soil and climate potential of the territories and material and technical resources in order to ensure highly profitable sustainable crops yields

Assessment of the impact of agricultural technologies on the fertility, health and stability of chernozem

This study aimed to comprehensively evaluate the effects of agricultural technologies on the quality, health, and stability of slightly eroded chernozem in grain crop rotation using the author's methodology. The research was conducted on the experimental field of the Kursk FANC from 2018 to 2021. Three agricultural technologies were tested: a traditional method with crushed by-products (PP), agrobiotechnology-1 (PP and microbiological preparations), and agrobiotechnology-2 (agrobiotechnology-1 + 10 kg a.i. N per 1 t of PP). The results showed that all technologies had a satisfactory impact on soil fertility, health, and stability, with most indicators remaining unchanged. Agrobiotechnology-1 had a good impact on soil fertility and stability and an excellent impact on soil health. Agrobiotechnology-2 had an excellent impact on soil, with significant and highly significant increases in most indicators. The comprehensive assessment indicated that agrobiotechnology-2 had the highest overall impact, with a Kcomp value of 21.4%

In Vivo Stability of Polyurethane-Based Electrospun Vascular Grafts in Terms of Chemistry and Mechanics

The biostability of the polyurethanes Tecoflex EG-80A and Pellethane 2363-80A, used as basic polymers of the vascular grafts (VGs) produced by electrospinning, as well as the tensile strength of Tecoflex VGs, are studied. Solutions of Tecoflex or Pellethane with gelatin and bivalirudin in 1,1,1,3,3,3-hexafluoroisopropanol are used for VG production. After 1, 12, and 24 weeks of VG implantation in the infrarenal position of the abdominal aorta of Wistar rats, VGs are explanted, fixed in formalin, freed from outer tissues, dialyzed, and dried. The polyurethanes are extracted from VGs by dispersion/extraction in tetrahydrofuran (THF) and freed from the excess of THF-insoluble biopolymers. The stability of polyurethanes is assessed by IR spectroscopy and gel permeation chromatography. Pellethane has emerged to be stable at all experimental points. Tecoflex loses approximately 10% of its molecular weight (both Mn and Mw) after 3 months and restored its initial value within 6 months of its functioning as a graft. Mechanical testing demonstrates a 30% reduction in the tensile strength after 3 months in VG and a 10% increase after 6 months. The stability and mechanical properties of polyurethane-based VGs demonstrate their utility for the reconstitution of damaged arteries

Self-Assembled Nanoparticles Based on Block-Copolymers of Poly(2-Deoxy-2-methacrylamido-d-glucose)/Poly(N-Vinyl Succinamic Acid) with Poly(O-Cholesteryl Methacrylate) for Delivery of Hydrophobic Drugs

The self-assembly of amphiphilic block-copolymers is a convenient way to obtain soft nanomaterials of different morphology and scale. In turn, the use of a biomimetic approach makes it possible to synthesize polymers with fragments similar to natural macromolecules but more resistant to biodegradation. In this study, we synthesized the novel bio-inspired amphiphilic block-copolymers consisting of poly(N-methacrylamido-d-glucose) or poly(N-vinyl succinamic acid) as a hydrophilic fragment and poly(O-cholesteryl methacrylate) as a hydrophobic fragment. Block-copolymers were synthesized by radical addition–fragmentation chain-transfer (RAFT) polymerization using dithiobenzoate or trithiocarbonate chain-transfer agent depending on the first monomer, further forming the hydrophilic block. Both homopolymers and copolymers were characterized by 1H NMR and Fourier transform infrared spectroscopy, as well as thermogravimetric analysis. The obtained copolymers had low dispersity (1.05–1.37) and molecular weights in the range of ~13,000–32,000. The amphiphilic copolymers demonstrated enhanced thermal stability in comparison with hydrophilic precursors. According to dynamic light scattering and nanoparticle tracking analysis, the obtained amphiphilic copolymers were able to self-assemble in aqueous media into nanoparticles with a hydrodynamic diameter of approximately 200 nm. An investigation of nanoparticles by transmission electron microscopy revealed their spherical shape. The obtained nanoparticles did not demonstrate cytotoxicity against human embryonic kidney (HEK293) and bronchial epithelial (BEAS-2B) cells, and they were characterized by a low uptake by macrophages in vitro. Paclitaxel loaded into the developed polymer nanoparticles retained biological activity against lung adenocarcinoma epithelial cells (A549)

Correction: Gostev et al. In Vivo Stability of Polyurethane-Based Electrospun Vascular Grafts in Terms of Chemistry and Mechanics. Polymers 2020, 12, 845

The authors wish to make a change to the published paper [...

Rhenium(I) Block Copolymers Based on Polyvinylpyrrolidone: A Successful Strategy to Water-Solubility and Biocompatibility

A series of diphosphine Re(I) complexes Re1&ndash;Re4 have been designed via decoration of the archetypal core {Re(CO)2(N^N)} through the installations of the phosphines P0 and P1 bearing the terminal double bond, where N^N = 2,2&prime;-bipyridine (N^N1), 4,4&prime;-di-tert-butyl-2,2&prime;-bipyridine (N^N2) or 2,9-dimethyl-1,10-phenanthroline (N^N3) and P0 = diphenylvinylphosphine, and P1 = 4-(diphenylphosphino)styrene. These complexes were copolymerized with the corresponding N-vinylpyrrolidone-based Macro-RAFT agents of different polymer chain lengths to give water-soluble copolymers of low-molecular p(VP-l-Re) and high-molecular p(VP-h-Re) block-copolymers containing rhenium complexes. Compounds Re1&ndash;Re4, as well as the copolymers p(VP-l-Re) and p(VP-h-Re), demonstrate phosphorescence from a 3MLCT excited state typical for this type of chromophores. The copolymers p(VP-l-Re#) and p(VP-h-Re#) display weak sensitivity to molecular oxygen in aqueous and buffered media, which becomes almost negligible in the model physiological media. In cell experiments with CHO-K1 cell line, p(VP-l-Re2) and p(VP-h-Re2) displayed significantly reduced toxicity compared to the initial Re2 complex and internalized into cells presumably by endocytic pathways, being eventually accumulated in endosomes. The sensitivity of the copolymers to oxygen examined in CHO-K1 cells via phosphorescence lifetime imaging microscopy (PLIM) proved to be inessential