Experiment K-6-23. Effect of spaceflight on levels and function of immune cells

Two different immunology experiments were performed on samples received from rats flown on Cosmos 1887. In the first experiment, rat bone marrow cells were examined in Moscow for their response to colony stimulating factor-M. In the second experiment, rat spleen and bone marrow cells were stained in Moscow with a variety of antibodies directed against cell surface antigenic markers. These cells were preserved and shipped to the United States where they were subjected to analysis on a flow cytometer. The results of the studies indicate that bone marrow cells from flown rats showed a decreased response to colony stimulating factor than did bone marrow cells from control rats. There was a higher percentage of spleen cells from flown rats staining positively for pan-T-cell, suppressor-T-cell and innate interleukin-2 receptor antigens than from control animals. In addition, a higher percentage of cells that appeared to be part of the myelogenous population of bone marrow cells from flown rats stained positively for surface immunoglobulin than did equivalent cells from control rats

Antibodies to myofibril antigens in cosmonauts after spaceflights

Serum samples obtained from 15 astronauts before and after spaceflights were studied with the use of the indirect immunofluorescent method. In seven astronauts antibodies to different elements of the human heart muscle appeared after flights. Strong and very strong luminescence of the elements of heart muscle tissue was detected in the astronauts after the third space flight. In a study of the sera on sections of bovine heart muscle tissue the reactions of the sera taken before and after flight were found to show no essential differences

Selectively Tunable Luminescence of Perovskite Nanocrystals Embedded in Polymer Matrix Allows Direct Laser Patterning

Cesium lead halide perovskite nanocrystals (NCs) have gained enormous attention as promising light-emitting and light-converting materials. Most of their applications require embedding NCs in various matrices, which is a challenging task due to their low stability, especially in the case of red-emitting CsPbI3 NCs. In this work, a new approach is proposed allowing the formation of red-emitting perovskite NCs by anion exchange induced directly inside a solid polymer matrix using green-emitting CsPbBr3 NCs as templates and iodododecane as an iodine source. Moreover, a simple and efficient route to photo-assisted termination of the anion exchange reaction in the polymer composite after reaching desired optical properties is demonstrated. The findings allow the authors to pattern a thin composite film with an ultrashort UV laser resulting in a selective generation of green- and red-emitting features with a 15 µm resolution

Colloidal Nanocrystals Embedded in Macrocrystals: Robustness, Photostability, and Color Purity

Cataloged from PDF version of article.The incorporation of colloidal quantum dots (QDs) into ionic crystals of various salts (NaCl, KCl, KBr, etc.) is demonstrated. The resulting mixed crystals of various shapes and beautiful colors preserve the strong luminescence of the incorporated QDs. Moreover, the ionic salts appear to be very tight matrices, ensuring the protection of the QDs from the environment and as a result providing them with extraordinary high photo- and chemical stability. A prototype of a white light-emitting diode (WLED) with a color conversion layer consisting of this kind of mixed crystals is demonstrated. These materials may also find applications in nonlinear optics and as luminescence standards

Epidemiology of hip fracture in Belarus: development of a country-specific FRAX model and its comparison to neighboring country models

Summary Fracture probabilities resulting from the newly generated FRAX model for Belarus based on regional estimates of the hip fracture incidence were compared with FRAX models of neighboring countries. Differences between the country-specific FRAX patterns and the rank orders of fracture probabilities were modest. Objective This paper describes the epidemiology of hip fractures in Belarus that was used to develop the country-specific fracture prediction FRAX® tool and illustrates its features compared to models for the neighboring countries of Poland, Russia, and Lithuania. Methods We carried out a population-based study in a region of Belarus (the city of Mozyr) representing approximately 1.2% of the country’s population. We aimed to identify all hip fractures in 2011–2012 from hospital registers and primary care sources. Age- and sex-specific incidence and national mortality rates were incorporated into a FRAX model for Belarus. Fracture probabilities were compared with those derived from FRAX models in neighboring countries. Results The estimated number of hip fractures nationwide in persons over the age of 50 years for 2015 was 8250 in 2015 and is predicted to increase to 12,918 in 2050. The annual incidence of fragility hip fractures in individuals aged 50 years or more was 24.6/10,000 for women and 14.6/10,000 for men, standardized to the world population. The comparison with FRAX models in neighboring countries showed that hip fracture probabilities in men and women in Belarus were similar to those in Poland, Russia, and Lithuania. The difference in incidence rates between the surveys including or excluding data from primary care suggested that 29.1% of patients sustaining a hip fracture were not hospitalized and, therefore, did not receive specialized medical care. Conclusion A substantial proportion of hip fractures in Belarus does not come to hospital attention. The FRAX model should enhance accuracy of determining fracture probability among the Belarus population and help guide decisions about treatment

Precise Engineering of Nanocrystal Shells via Colloidal Atomic Layer Deposition

We present a general strategy for a facile synthesis of complex multifunctional nanoscale materials via colloidal atomic layer deposition (c-ALD). The c-ALD technique is based on self-limiting half-reactions of ionic precursors on the surface of a nanocrystal (NC) occurring at room temperature. Using this technique, uniform layers of CdS and ZnS semiconductor shells were epitaxially grown on CdSe semiconductor cores with different shell combinations, leading to the precise control of the optical properties of these heterostructures. All core-shell multicomponent nanoparticles preserve narrow size distributions, phase crystallinity, and shape homogeneity of the initial NCs. Furthermore, we attempted to extend the toolbox of the c-ALD to combine materials with intrinsically different properties, such as Au/CdS core/shell structures with substantial lattice mismatch. The results presented in this work demonstrate great opportunities for creating functional materials with programmable properties for electronics and optoelectronics

A surrogate FRAX model for the Kyrgyz Republic

Summary The hip fracture rates from Kazakhstan were used to create a surrogate FRAX® model for the Kyrgyz Republic. Introduction The International Society for Clinical Densitometry and International Osteoporosis Foundation recommend utilizing a surrogate FRAX model, based on the country-specific risk of death, and fracture data based on a country where fracture rates are considered to be representative of the index country. Objective This paper describes a surrogate FRAX model for the Kyrgyz Republic. Methods The FRAX model used the incidence of hip fracture from the neighbouring country of Kazakhstan and the death risk for the Kyrgyz Republic. Results Compared with the model for Kazakhstan, the surrogate model gave somewhat higher 10-year fracture probabilities for men between 60 and 80 years of age and lower probabilities for men above the age of 80. For women the probabilities were similar up to the age of 75–80 years and then lower. There were very close correlations in fracture probabilities between the surrogate and authentic models (1.00) so that the use of the Kyrgyz model had little impact on the rank order of risk. It was estimated that 2752 hip fractures arose in 2015 in individuals over the age of 50 years in the Kyrgyz Republic, with a predicted increase by 207% to 8435 in 2050. Conclusion The surrogate FRAX model for the Kyrgyz Republic provides the opportunity to determine fracture probability among the Kyrgyz population and help guide decisions about treatment

Function of the ribosomal E-site: a mutagenesis study

Ribosomes synthesize proteins according to the information encoded in mRNA. During this process, both the incoming amino acid and the nascent peptide are bound to tRNA molecules. Three binding sites for tRNA in the ribosome are known: the A-site for aminoacyl-tRNA, the P-site for peptidyl-tRNA and the E-site for the deacylated tRNA leaving the ribosome. Here, we present a study of Escherichia coli ribosomes with the E-site binding destabilized by mutation C2394G of the 23S rRNA. Expression of the mutant 23S rRNA in vivo caused increased frameshifting and stop codon readthrough. The progression of these ribosomes through the ribosomal elongation cycle in vitro reveals ejection of deacylated tRNA during the translocation step or shortly after. E-site compromised ribosomes can undergo translocation, although in some cases it is less efficient and results in a frameshift. The mutation affects formation of the P/E hybrid site and leads to a loss of stimulation of the multiple turnover GTPase activity of EF-G by deacylated tRNA bound to the ribosome

The capabilities of MRI in the lung lesions diagnosis in patients with COVID-19

Backgrounds. The imaging diagnostic methods have become particularly important during the COVID-19 pandemic, and computed tomography of the thorax (CT) is considered to be the gold standard in the cases of lung lesions and in the evaluation of changes in the pulmonary parenchyma in dynamics. However, it is well known that the CT method is associated with a significant radiation dose, especially given the fact that repeated, and often reiterated control CT-tests are required for many patients who suffer COVID-19 or have recovered from the disease. In order to reduce the potential radiation exposure and receive some additional diagnostic information, we applied the magnetic resonance imaging (MRI) method for viral pneumonia at the FRCC of FMBA of Russia, which was redesigned as a center for the treatment of patients with COVID-19. Aim. The aim is to evaluate the possibilities of the lung MRI in the diagnosis of pneumonia caused by the new coronaviral infection, to describe the specific symptoms of lung parenchyma lesions using various pulse sequences, and compare the results with the CT data. Methods. The article is based on the practice of applying high-resolution computed tomography (HRCT) and MRI of the lungs in 15 patients with pneumonia caused by COVID-19. Results. The comparison of the HRCT data and T2-weighted images (T2-WI) in 100% of cases revealed a complete correlation in the size, number and position of the lung tissue areas with reduced air saturation by the type of ground glass opacity and the consolidation zones. The level of linear and reticular changes detection in MRI reached 73.3%. Free fluid in the pleural cavities in a moderate and minimal volume was revealed on T2-WI in 12 patients (80% of cases), while it was not diagnosed by HRCT in all the cases. The mediastinal and intra-pulmonary lymph nodes were visualized distinctly. In T1-weighted images (T1-WI), the areas of ground glass opacity were either not visualized, or were represented by smaller areas when compared to the HRCV data and reticular changes were also displayed worse. In 73.3% cases, the consolidation zones on T1-WI fully corresponded or were almost similar in characteristics to changes visualized by HRCT. At the same time, it is worth noting that performing T1-WI out phase more clearly displayed the consolidation zones when compared to T1-WI in phase. Foci of increased signal on T1-WI with fat suppression were registered in 3 patients against the background of consolidation sites which in comparison with the data of T2-WI, would suggest the presence of parenchymal hemorrhages. Conclusion. Lung MRI is a fairly sensitive method for identifying areas of ground glass opacity and consolidation, reticular changes and lymphadenopathy, and is superior to HRCT when displaying pleural effusion. Chest MRI may be recommended as a diagnostic method for suspected pulmonary COVID-19 lesion in children and pregnant women in order to exclude ionizing radiation exposure, as well as for monitoring the condition of lung tissue after viral pneumonia, if the patient was previously exposed to a high radiation dose

Flexible and fragmentable tandem photosensitive nanocrystal skins

We proposed and demonstrated the first account of large-area, semi-transparent, tandem photosensitive nanocrystal skins (PNSs) constructed on flexible substrates operating on the principle of photogenerated potential buildup, which avoid the need for applying an external bias and circumvent the currentmatching limitation between junctions. We successfully fabricated and operated the tandem PNSs composed of single monolayers of colloidal water-soluble CdTe and CdHgTe nanocrystals (NCs) in adjacent junctions on a Kapton polymer tape. Owing to the usage of a single NC layer in each junction, noise generation was significantly reduced while keeping the resulting PNS films considerably transparent. In each junction, photogenerated excitons are dissociated at the interface of the semi-transparent Al electrode and the NC layer, with holes migrating to the contact electrode and electrons trapped in the NCs. As a result, the tandem PNSs lead to an open-circuit photovoltage buildup equal to the sum of those of the two single junctions, exhibiting a total voltage buildup of 128.4 mV at an excitation intensity of 75.8 μW cm⁻² at 350 nm. Furthermore, we showed that these flexible PNSs could be bent over 3.5 mm radius of curvature and cut out in arbitrary shapes without damaging the operation of individual parts and without introducing any significant loss in the total sensitivity. These findings indicate that the NC skins are promising as building blocks to make low-cost, flexible, large-area UV/visible sensing platforms with highly efficient full-spectrum conversion