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排序方式: 共有2709条查询结果,搜索用时 15 毫秒
81.
Sergey Mironov Charles D. Hwang Jean Nemzek John Li Kavitha Ranganathan Jonathan T. Butts David J. Cholok Vladislav A. Dolgachev Stewart C. Wang Mark Hemmila Paul S. Cederna Michael D. Morris Omer Berenfeld Benjamin Levi 《Wound repair and regeneration》2020,28(2):185-193
Existing clinical approaches and tools to measure burn tissue destruction are limited resulting in misdiagnosis of injury depth in over 40% of cases. Thus, our objective in this study was to characterize the ability of short‐wave infrared (SWIR) imaging to detect moisture levels as a surrogate for tissue viability with resolution to differentiate between burns of various depths. To accomplish our aim, we constructed an imaging system consisting of a broad‐band Tungsten light source; 1,200‐, 1,650‐, 1,940‐, and 2,250‐nm wavelength filters; and a specialized SWIR camera. We initially used agar slabs to provide a baseline spectrum for SWIR light imaging and demonstrated the differential absorbance at the multiple wavelengths, with 1,940 nm being the highest absorbed wavelength. These spectral bands were then demonstrated to detect levels of moisture in inorganic and in vivo mice models. The multiwavelength SWIR imaging approach was used to diagnose depth of burns using an in vivo porcine burn model. Healthy and injured skin regions were imaged 72 hours after short (20 seconds) and long (60 seconds) burn application, and biopsies were extracted from those regions for histologic analysis. Burn depth analysis based on collagen coagulation histology confirmed the formation of superficial and deep burns. SWIR multispectral reflectance imaging showed enhanced intensity levels in long burned regions, which correlated with histology and distinguished between superficial and deep burns. This SWIR imaging method represents a novel, real‐time method to objectively distinguishing superficial from deep burns. 相似文献
82.
Alexander Chernyavskiy MD PhD Sergey Alsov MD Kseniya Guliaeva Ivan Porshennikov MD PhD 《Journal of cardiac surgery》2020,35(11):3199-3201
We report a rare case of liver alveolar echinococcosis with an invasion of the hepaticocaval confluence, inferior vena cava, pericardium, right atrium, atrial septum, and superior vena cava, and its successful treatment by combined heart-liver transplantation. 相似文献
83.
84.
Ashot H. Gevorgyan Sergey S. Golik Nikolay A. Vanyushkin Ilya M. Efimov Mushegh S. Rafayelyan Hermine Gharagulyan Tatevik M. Sarukhanyan Meruzhan Z. Hautyunyan Gvidon K. Matinyan 《Materials》2021,14(9)
In our paper, the magneto-optical properties of a dichroic cholesteric liquid crystal layer with large values of magneto-optical parameter g and low values of dielectric permittivity were investigated. The solutions of the dispersion equation and their peculiarities were investigated in detail. The specific properties of reflection, transmission, absorption, rotation, ellipticity spectra and also the spectra of ellipticity and azimuth of eigen polarization were investigated. The existence of a tunable linear and nonreciprocal transmission band was shown. 相似文献
85.
Daria Gognieva Yulia Mitina Timur Gamilov Roman Pryamonosov Yuriy Vasilevskii Sergey Simakov Fuyou Liang Sergey Ternovoy Natalya Serova Ekaterina Tebenkova Valentin Sinitsyn Ekaterina Pershina Sergey Abugov Gaik Mardanian Narek Zakarian Vardan Kirakosian Vladimir Betelin Dmitry Shchekochikhin Abram Syrkin Philippe Kopylov 《Global Heart》2021,16(1)
Background:Until recently, Russia did not utilize noninvasive fractional flow reserve (FFR) assessment. We developed an automated algorithm for noninvasive assessment of FFR based on a one-dimensional (1D) mathematical modeling.Objective:The research aims to evaluate the diagnostic accuracy of this algorithm.Methods:The study enrolled 80 patients: 16 of them underwent 64-slice computed tomography – included retrospectively, 64 – prospectively, with a 640-slice CT scan. Specialists processed CT images and evaluated noninvasive FFR. Ischemia was confirmed if FFR < 0.80 and disproved if FFR ≥ 0.80. The prospective group of patients was hospitalized for invasive FFR assessment as a reference standard. If ischemic, patients underwent stent implantation. In the retrospective group, patients already had invasive FFR values.Statistical analysis was performed using GraphPad Prism 8. We compared two methods using a Bland–Altman plot and per-vessel ROC curve analysis. Considering the abnormality of distribution by the Kolmogorov-Smirnov test, we have used Spearman’s rank correlation coefficient.Results:During data processing, three patients of the retrospective and 46 patients of the prospective group were excluded. The sensitivity of our method was 66.67% (95% CI: 46.71–82.03); the specificity was 78.95% (95% CI: 56.67–91.49), p = 0.0052, in the per-vessel analysis. In per-patient analysis, the sensitivity was 69.57% (95% CI: 49.13–84.40); the specificity was 87.50% (95% CI: 52.91–99.36), p = 0.0109. The area under the ROC curve in the per-vessel analysis was 77.52% (95% CI: 66.97–88.08), p < 0.0001.Conclusion:The obtained indices of sensitivity, specificity, PPV, and NPV are, in general, comparable to those in other studies. Moreover, the noninvasive values of FFR yielded a high correlation coefficient with the invasive values. However, the AUC was not high enough, 77.52 (95% CI: 66.97–88.08), p < 0.0001. The discrepancy is probably attributed to the initial data heterogeneity and low statistical power. 相似文献
86.
Gabriel Constantinescu Sergey M. Mikhalev Aleksey D. Lisenkov Daniela V. Lopes Artur R. Sarabando Marta C. Ferro Tiago F. da Silva Sergii A. Sergiienko Andrei V. Kovalevsky 《Materials》2021,14(4)
This work further explores the possibilities for designing the high-temperature electrical performance of the thermoelectric Ca3Co4O9 phase, by a composite approach involving separate metallic iron and nickel particles additions, and by employing two different sintering schemes, capable to promote the controlled interactions between the components, encouraged by our recent promising results obtained for similar cobalt additions. Iron and nickel were chosen because of their similarities with cobalt. The maximum power factor value of around 200 μWm−1K−2 at 925 K was achieved for the composite with the nominal nickel content of 3% vol., processed via the two-step sintering cycle, which provides the highest densification from this work. The effectiveness of the proposed approach was shown to be strongly dependent on the processing conditions and added amounts of metallic particles. Although the conventional one-step approach results in Fe- and Ni-containing composites with the major content of the thermoelectric Ca3Co4O9 phase, their electrical performance was found to be significantly lower than for the Co-containing analogue, due to the presence of less-conducting phases and excessive porosity. In contrast, the relatively high performance of the composite with a nominal nickel content of 3% vol. processed via a two-step approach is related to the specific microstructural features from this sample, including minimal porosity and the presence of the Ca2Co2O5 phase, which partially compensate the complete decomposition of the Ca3Co4O9 matrix. The obtained results demonstrate different pathways to tailor the phase composition of Ca3Co4O9-based materials, with a corresponding impact on the thermoelectric performance, and highlight the necessity of more controllable approaches for the phase composition tuning, including lower amounts and different morphologies of the dispersed metallic phases. 相似文献
87.
Leshchinskiy Sergey Ali Naiim Akselrod Dmitriy D’Agostino Robert 《Abdominal imaging》2019,44(4):1608-1610
Abdominal Radiology - 相似文献
88.
89.
Sergey Kosourov Valria Nagy Dmitry Shevela Martina Jokel Johannes Messinger Yagut Allahverdiyeva 《Proceedings of the National Academy of Sciences of the United States of America》2020,117(47):29629
The unicellular green alga Chlamydomonas reinhardtii is capable of photosynthetic H2 production. H2 evolution occurs under anaerobic conditions and is difficult to sustain due to 1) competition between [FeFe]-hydrogenase (H2ase), the key enzyme responsible for H2 metabolism in algae, and the Calvin–Benson–Bassham (CBB) cycle for photosynthetic reductants and 2) inactivation of H2ase by O2 coevolved in photosynthesis. Recently, we achieved sustainable H2 photoproduction by shifting algae from continuous illumination to a train of short (1 s) light pulses, interrupted by longer (9 s) dark periods. This illumination regime prevents activation of the CBB cycle and redirects photosynthetic electrons to H2ase. Employing membrane-inlet mass spectrometry and , we now present clear evidence that efficient H2 photoproduction in pulse-illuminated algae depends primarily on direct water biophotolysis, where water oxidation at the donor side of photosystem II (PSII) provides electrons for the reduction of protons by H2ase downstream of photosystem I. This occurs exclusively in the absence of CO2 fixation, while with the activation of the CBB cycle by longer (8 s) light pulses the H2 photoproduction ceases and instead a slow overall H2 uptake is observed. We also demonstrate that the loss of PSII activity in DCMU-treated algae or in PSII-deficient mutant cells can be partly compensated for by the indirect (PSII-independent) H2 photoproduction pathway, but only for a short (<1 h) period. Thus, PSII activity is indispensable for a sustained process, where it is responsible for more than 92% of the final H2 yield.Many species of green algae have [FeFe]-hydrogenases (H2ases) (1) that catalyze the reversible reduction of protons to molecular hydrogen:[1]Since [FeFe]-H2ases are extremely O2-sensitive (2), reaction 1 typically proceeds under anoxic conditions. With respect to H2 metabolism, Chlamydomonas reinhardtii is the most studied alga. This alga possesses two [FeFe]-H2ases in the chloroplast, HYDA1 and HYDA2 (3, 4). In the light, they accept electrons from photosynthetically reduced ferredoxin (FDX1) (5), while in the dark electrons come from the activity of pyruvate ferredoxin oxidoreductase (PFR1) (6). PFR1 catalyzes the oxidation of pyruvate to acetyl-CoA, and its activity is linked to H2ase via FDX1 (7). Since [FeFe]-H2ases interact with the photosynthetic electron transport chain at the level of ferredoxin, they may accept electrons originating both from water oxidation via the photosystem II (PSII)-dependent pathway (“direct water biophotolysis”) and from the degradation of organic substrates via a PSII-independent mechanism (“indirect water biophotolysis” or “indirect pathway”) (8). In the latter case, the reductants are supplied to the plastoquinone (PQ) pool by the type II NADPH dehydrogenase (NDA2), thus bypassing PSII (9, 10).The release of H2 leads to a loss of metabolic energy. In healthy, actively growing C. reinhardtii cultures, H2 production is therefore only a temporal phenomenon observed during dark anoxia and upon subsequent onset of illumination (11). In contrast to dark fermentation, H2 photoproduction is a very efficient process that proceeds for only a short period of time (from a few seconds to a few minutes). Two theories have been developed to explain the short duration. The first is based on the oxygen sensitivity of H2ases (12, 13). In the light, algae accumulate O2 that is produced by water oxidation at PSII (14). As a result, H2 photoproduction may cease over time (14, 15), and the duration of this process is reported to shorten with increased light intensity (16). Because of the negative correlation between the rates of H2 photoproduction and O2 evolution, the inhibition of H2ases by O2 is frequently quoted as the primary reason for the rapid loss in H2 photoproduction after the onset of illumination (17).Alternatively, the loss in the H2 photoproduction efficiency during illumination could be explained by the light-induced induction of competitive pathways, which may drain reducing equivalents away from the [FeFe]-H2ase enzyme (18, 19). Candidates for this role are the Mehler-like reaction driven by flavodiiron proteins (FDPs) (15, 20, 21) and the Calvin–Benson–Bassham (CBB) cycle (22). Compelling evidence for the competition between these two pathways and H2 production has been accumulated in recent studies (23–25). As CO2 fixation provides the strongest sink for photosynthetic reductants, it should play a major role in the cessation of H2 photoproduction in algae when the CBB cycle is active (19, 22).For preventing competition between the [FeFe]-H2ases and the CBB cycle, we recently devised a pulse-illumination protocol that allows H2 production in nutrient-replete algal cultures for up to 3 d (23). To achieve this, we specifically selected the duration of light pulses in the light/dark sequence to avoid activation of the CBB cycle, thus allowing for the redirection of photosynthetic electrons toward the [FeFe]-H2ases. Typically, a train of 1- to 6-s light pulses interrupted by 9-s dark periods is sufficient for sustained H2 photoproduction in C. reinhardtii cultures (23, 25). Our protocol thus differs from earlier pulse-illumination approaches that aimed at preventing the accumulation of O2 in the cultures (26).While we could demonstrate competition of [FeFe]-H2ase with FDPs (25), the origin of reductants for H2 photoproduction in the pulse-illuminated algae remained unclear. The relatively high efficiency of the process suggests the involvement of water oxidation by PSII, and consequently the simultaneous production of H2 and O2. Although widely proposed in the current literature (8, 24), the presence of the direct water biophotolysis in H2-producing green algae has not yet been proven by direct experimental data.In the present study, we provide clear evidence for the presence of PSII-dependent oxidation of 18O-labeled water with concomitant evolution of 16O2 and 16,18O2 during H2 photoproduction in the pulse-illuminated green alga C. reinhardtii under anoxic conditions. O2 evolution is balanced by light-dependent and light-independent respiration that sustains the anoxic condition. We also demonstrate that the loss of PSII activity in algae can be partly compensated by the PSII-independent H2 photoproduction pathway. Nevertheless, the activity of PSII is indispensable for the sustained process, where it contributes to more than 92% of the final H2 yield. 相似文献
90.
Larisa Rudenko Julia Desheva Sergey Korovkin Alexander Mironov Andrey Rekstin Elena Grigorieva Svetlana Donina Alexandra Gambaryan Anton Katlinsky 《Influenza and other respiratory viruses》2008,2(6):203-209
Objective Our studies aimed to evaluate in clinical trials the safety and immunogenicity of an H5 live influenza vaccine candidate obtained using classical reassortment techniques from a low pathogenicity avian influenza (LPAI) A/Duck/Potsdam/1402‐6/86(H5N2) virus and the cold‐adapted (ca) donor strain A/Leningrad/134/17/57(H2N2). Methods During Phase I–II clinical trials, volunteers received intranasally two doses of reassortant influenza vaccine strain A/17/Duck/Potsdam/86/92 (H5N2) 21 days apart. Clinical examination of all vaccinees was conducted 7 days post‐vaccination. Serum antibody responses were measured by hemagglutination‐inhibition and microneutralization and local antibodies were estimated using an enzyme‐linked immunosorbent assay test. Results The vaccine was safe and of low reactogenicity with no febrile reactions. After revaccination 47·1–54·8% of subjects showed ≥fourfold seroconversions of Hamagglutination inhibition (HAI) antibodies to the hemagglutinin (HA) antigen of the A/17/Duck/Potsdam/86/92 (H5N2) virus and 29·4–30·8% were seroconverted to the HA antigen of the reverse genetics reassortant A/Indonesia/05/2005 × PR8 IBCDC‐RG (H5N1). Virus‐neutralizing antibody levels in sera of volunteers were similar to those shown in HAI test. The virus‐specific nasal IgA antibody response after two vaccine doses demonstrated significant increases of ≥fourfold rise SIgA antibodies (65%) geometrical mean titers (16·0) and a rise in SIgA antibodies (2·8) compared with one dose. Conclusion The live attenuated influenza vaccine candidate prepared using the LPAI A(H5N2) strain was well tolerated and elicited serum and local immune responses. There was evident cross‐reactivity to the A(H5N1) strain in the HAI test. 相似文献