Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 675
Filtrar
1.
Front Neurol ; 14: 1183265, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37521297

RESUMEN

Odors evoking vivid and intensely felt autobiographical memories are known as the "Proust phenomenon," delineating the particularity of olfaction in being more effective with eliciting emotional memories than other sensory modalities. The phenomenon has been described extensively in healthy participants as well as in patients during pre-epilepsy surgery evaluation after focal stimulation of the amygdalae and post-traumatic stress disorder (PTSD). In this study, we provide the inaugural description of aversive odor-evoked autobiographical memories after stroke in the right hippocampal, parahippocampal, and thalamic nuclei. As potential underlying neural signatures of the phenomenon, we discuss the disinhibition of limbic circuits and impaired communication between the major networks, such as saliency, central executive, and default mode network.

2.
Biometals ; 36(3): 437-462, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-36334191

RESUMEN

The pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection involves dysregulations of iron metabolism, and although the mechanism of this pathology is not yet fully understood, correction of iron metabolism pathways seems a promising pharmacological target. The previously observed effect of inhibiting SARS-CoV-2 infection by ferristatin II, an inducer of transferrin receptor 1 (TfR1) degradation, prompted the study of competition between Spike protein and TfR1 ligands, especially lactoferrin (Lf) and transferrin (Tf). We hypothesized molecular mimicry of Spike protein as cross-reactivity of Spike-specific antibodies with Tf and Lf. Thus, strong positive correlations (R2 > 0.95) were found between the level of Spike-specific IgG antibodies present in serum samples of COVID-19-recovered and Sputnik V-vaccinated individuals and their Tf-binding activity assayed with peroxidase-labeled anti-Tf. In addition, we observed cross-reactivity of Lf-specific murine monoclonal antibody (mAb) towards the SARS-CoV-2 Spike protein. On the other hand, the interaction of mAbs produced to the receptor-binding domain (RBD) of the Spike protein with recombinant RBD protein was disrupted by Tf, Lf, soluble TfR1, anti-TfR1 aptamer, as well as by peptides RGD and GHAIYPRH. Furthermore, direct interaction of RBD protein with Lf, but not Tf, was observed, with affinity of binding estimated by KD to be 23 nM and 16 nM for apo-Lf and holo-Lf, respectively. Treatment of Vero E6 cells with apo-Lf and holo-Lf (1-4 mg/mL) significantly inhibited SARS-CoV-2 replication of both Wuhan and Delta lineages. Protective effects of Lf on different arms of SARS-CoV-2-induced pathogenesis and possible consequences of cross-reactivity of Spike-specific antibodies are discussed.


Asunto(s)
COVID-19 , Lactoferrina , Imitación Molecular , Glicoproteína de la Espiga del Coronavirus , Transferrina , Animales , Humanos , Ratones , Hierro/metabolismo , Lactoferrina/química , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/metabolismo , Transferrina/química
3.
Phys Rev Lett ; 131(24): 241001, 2023 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-38181145

RESUMEN

A recent discovery of additional mechanism of electroluminescence (EL) in noble gases due to the neutral bremsstrahlung (NBrS) effect led to a prediction that NBrS EL should be present in noble liquids as well. A theoretical model of NBrS EL in noble liquids was developed accordingly in the frameworks of Cohen-Lekner and Atrazhev. In this work, we confirm this prediction: For the first time, visible-range EL has been observed in liquid argon at electric fields reaching 90 kV/cm, using gas electron multiplier (GEM) and thick GEM structures. Absolute light yields of the EL were measured and found to be in excellent agreement with the theory, provided that the momentum-transfer cross section of electron scattering is used for calculation of the NBrS cross section (instead of the energy-transfer one).

4.
Opt Express ; 30(11): 19332-19342, 2022 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-36221714

RESUMEN

The results of the investigation of the reflective characteristics of multilayer mirrors based on Ru/Y are presented. Reflection coefficients at the level of 38.5% at an operating wavelength of 9.4 nm. It is shown that the deposition of B4C barrier layers onto Y layers makes it possible to significantly increase the reflection coefficient compared to structures without barrier layers. A reflectance of 54% was obtained for mirrors optimized for 11.4 nm, which is close to the theoretical limit for these materials.

5.
Arch Biochem Biophys ; 728: 109353, 2022 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-35853481

RESUMEN

Myeloperoxidase (MPO), an oxidant-producing enzyme of neutrophils, has been shown to prime platelet activity promoting immunothrombosis. Native MPO is a homodimer, consisting of two identical protomers (monomer) connected by a single disulfide bond. But in inflammatory foci, MPO can be found both in the form of a monomer and in the form of a dimer. Beside MPO can also be in complexes with other molecules and be modified by oxidants, which ultimately affect its physicochemical properties and functions. Here we compared the effects of various forms of MPO as well as MPO in complex with ceruloplasmin (CP), a physiological inhibitor of MPO, on the platelet activity. Monomeric MPO (hemi-MPO) was obtained by treating the dimeric MPO by reductive alkylation. MPO was modified with HOCl in a molar ratio of 1:100 (MPO-HOCl). Using surface-enhanced Raman scattering (SERS) spectroscopy we showed that peaks at about 510 and 526 cm-1 corresponded to disulfide bond was recognizable in the SERS-spectra of dimeric MPO, absent in the spectrum of hemi-MPO and less intense in the spectra of MPO-HOCl, which indicates the partial decomposition of dimeric MPO with a disulfide bond cleavage under the HOCl modification. It was shown hemi-MPO to a lesser extent than dimeric MPO bound to platelets and enhanced their agonist-induced aggregation and platelet-neutrophil aggregate formation. MPO modified by HOCl and MPO in complex with CP did not bind to platelets and have no effect on platelet activity. Thus, the modification of MPO by HOCl, its presence in monomeric form as well as in complex with CP reduces MPO effect on platelet function and consequently decreases the risk of thrombosis in inflammatory foci.


Asunto(s)
Neutrófilos , Peroxidasa , Colorantes , Disulfuros , Ácido Hipocloroso , Oxidantes , Activación Plaquetaria
6.
Bull Exp Biol Med ; 173(2): 261-264, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35737160

RESUMEN

We performed a comparative quantitative analysis of LINE-1 mRNA levels in extracellular total plasma RNA in patients with colon cancer and practically healthy donors. Quantitative multiplex PCR with reverse transcription was used to assess the level of LINE-1 and 18S rRNA mRNA in extracellular total plasma RNA. The median of LINE-1 mRNA values in colon cancer patients (4.95) was significantly higher than in healthy donors (2.3) (p=0.037). It was shown for the first time that the level of LINE-1 mRNA in total RNA from blood plasma can be determined in the format of a liquid biopsy and serve as a new potential non-invasive marker of colon cancer.


Asunto(s)
Ácidos Nucleicos Libres de Células , Neoplasias del Colon , Neoplasias Colorrectales , Proteínas de Unión al ARN , Biomarcadores de Tumor/sangre , Biomarcadores de Tumor/genética , Ácidos Nucleicos Libres de Células/sangre , Ácidos Nucleicos Libres de Células/genética , Neoplasias del Colon/sangre , Neoplasias del Colon/genética , Neoplasias Colorrectales/sangre , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Humanos , ARN Mensajero/sangre , ARN Mensajero/genética , Proteínas de Unión al ARN/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa
7.
Appl Radiat Isot ; 182: 110147, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-35202921

RESUMEN

The results of the development and research of the characteristics of a new gamma activation analysis (GAA) facility, created for the quantitative analysis of gold-bearing ores in real conditions of a gold-mining enterprise, are presented. The values of the gold detection limit (3σ), measured from the spectra of certified reference samples with an ultralow background level, were 0.025-0.028 ppm with a single irradiation. In this case, the root-mean-square measurement error for a gold concentration of 1 ppm did not exceed 8% and 4% for a concentration of 10 ppm. The GAA facility provides the analysis of coarse-ground samples (1-3 mm) with a capacity of at least 65 samples per hour.

8.
Artículo en Ruso | MEDLINE | ID: mdl-35157394

RESUMEN

The article presents the results of analysis of specialized medical care of children with life threatening and chronic progressive rare (orphan) diseases resulting in life span shortening or disability. The possibility of medication support of children with rare diseases. The development of patient routing system considering characteristics of particular disease and possibilities of the subjects of the Russian Federation is one of most important directions of enhancement of needed medical care support.


Asunto(s)
Personas con Discapacidad , Enfermedades Raras , Niño , Humanos , Longevidad , Atención al Paciente , Enfermedades Raras/epidemiología , Enfermedades Raras/terapia , Federación de Rusia
9.
J Chem Phys ; 155(1): 014505, 2021 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-34241375

RESUMEN

Oscillatory shear rheology has been employed to access the structural rearrangements of deeply supercooled sulfuric acid tetrahydrate (SA4H) and phosphoric acid monohydrate, the latter in protonated (PA1H) and deuterated (PA1D) forms. Their viscoelastic responses are analyzed in relation to their previously investigated electric conductivity. The comparison of the also presently reported dielectric response of deuterated sulfuric acid tetrahydrate (SA4D) and that of its protonated analog SA4H reveals an absence of isotope effects for the charge transport in this hydrate. This finding clearly contrasts with the situation known for PA1H and PA1D. Our analyses also demonstrate that the conductivity relaxation profiles of acid hydrides closely resemble those exhibited by classical ionic electrolytes, even though the charge transport in phosphoric acid hydrates is dominated by proton transfer processes. At variance with this dielectric simplicity, the viscoelastic responses of these materials depend on their structural compositions. While SA4H displays a "simple liquid"-like viscoelastic behavior, the mechanical responses of PA1H and PA1D are more complex, revealing relaxation modes, which are faster than their ubiquitous structural rearrangements. Interestingly, the characteristic rates of these fast mechanical relaxations agree well with the characteristic frequencies of the charge rearrangements probed in the dielectric investigations, suggesting appearance of a proton transfer in mechanical relaxation of phosphoric acid hydrates. These findings open the exciting perspective of exploiting shear rheology to access not only the dynamics of the matrix but also that of the charge carriers in highly viscous decoupled conductors.

10.
Spectrochim Acta A Mol Biomol Spectrosc ; 255: 119675, 2021 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-33744836

RESUMEN

Spectroscopy and microscopy in the so-called "water-window" is a holy grail of modern molecular biology. A pulsed source of coherent X-rays within this spectral window, falling between 2.3 nm and 4.4 nm, provides a unique tool for time-resolved imaging of bio-systems in their naturally water-rich state. Within this spectral range, water is mostly transparent, while proteins are mostly opaque. This results in a high-contrast image on the sub-cellular level. Here we present, for the first time, generation of a very high gain of G≈ 60/cm in He-like CV ions via transitions to the ground state at 4.03 nm in a table-top device.


Asunto(s)
Rayos Láser , Agua , Luz , Microscopía , Rayos X
11.
Biomed Khim ; 67(1): 66-73, 2021 Jan.
Artículo en Ruso | MEDLINE | ID: mdl-33645523

RESUMEN

The homodimeric glycoprotein, anti-mullerian hormone (AMH), described over 70 years ago by A. Jost, is the least studied member of the transforming growth factor beta superfamily. Despite the antitumor activity of AMH discovered at the end of the last century, the creation of effective drugs based on AMH is hindered primarily by the lack of information on the mechanism of various AMH forms interaction with a specific type II receptor (MISRII). Previously, we have shown that not only the full-length activated hormone but also its C-terminal fragment (C-rAMH) could bind to MISRII. In this work, using the surface plasmon resonance technique, we compared the interaction of three forms of recombinant AMH (rAMH) with the MISRII analogue - the chimeric protein MISRII-Fc containing AMH type II receptor and a Fc-fragment of the human IgG1 heavy chain. Comparison of the binding of MISRII-Fc, immobilized on a chip with group specificity for human immunoglobulins, to C-rAMH, to intact rAMH (pro-rAMH), and to rAMH containing one uncleaved monomer (hc-rAMH), showed that the KD of the complexes increased: 1.7 nM, 88 nM and 110 nM, respectively. Thus, we have shown that C-terminal fragment of AMH has the maximum affinity for the recombinant MISRII analogue, which indicates the prospects for the development of drugs based on this hormone derivative.


Asunto(s)
Hormona Antimülleriana , Factor de Crecimiento Transformador beta , Hormona Antimülleriana/genética , Humanos , Proteínas Recombinantes/genética
12.
Phys Rev E ; 103(2-1): 022134, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33736092

RESUMEN

The critical behavior of three-dimensional weakly diluted quenched Ising model is examined on the base of six-loop renormalization group expansions obtained within the minimal subtraction scheme in 4-ɛ space dimensions. For this purpose the ϕ^{4} field theory with cubic symmetry was analyzed in the replica limit n→0. Along with renormalization group expansions in terms of renormalized couplings the sqrt[ɛ] expansions of critical exponents are presented. Corresponding numerical estimates for the physical, three-dimensional system are obtained by means of different resummation procedures applied both to the sqrt[ɛ] series and to initial renormalization group expansions. The results given by the latter approach are in a good agreement with their counterparts obtained experimentally and within the Monte Carlo simulations, while resumming of sqrt[ɛ] series themselves turned out to be disappointing.

13.
Biochem Cell Biol ; 99(1): 109-116, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-32544357

RESUMEN

Myeloperoxidase (MPO) is a unique heme-containing peroxidase that can catalyze the formation of hypochlorous acid (HOCl). The strong interaction of MPO with low-density lipoproteins (LDL) promotes proatherogenic modification of LDL by HOCl. The MPO-modified LDL (Mox-LDL) accumulate in macrophages, resulting in the formation of foam cells, which is the pathognomonic symptom of atherosclerosis. A promising approach to prophylaxis and atherosclerosis therapy is searching for remedies that prevent the modification or accumulation of LDL in macrophages. Lactoferrin (LF) has several application points in obesity pathogenesis. We aimed to study LF binding to Mox-LDL and their accumulation in monocytes transformed into macrophages. Using surface plasmon resonance and ELISA techniques, we observed no LF interaction with intact LDL, whereas Mox-LDL strongly interacted with LF. The affinity of Mox-LDL to LF increased with the degree of oxidative modification of LDL. Moreover, an excess of MPO did not prevent interaction of Mox-LDL with LF. LF inhibits accumulation of cholesterol in macrophages exposed to Mox-LDL. The results obtained reinforce the notion of LF potency as a remedy against atherosclerosis.


Asunto(s)
Colesterol/metabolismo , Lactoferrina/metabolismo , Lipoproteínas LDL/metabolismo , Monocitos/metabolismo , Peroxidasa/metabolismo , Células Cultivadas , Colesterol/sangre , Colesterol/química , Voluntarios Sanos , Humanos , Lactoferrina/sangre , Lactoferrina/química , Lipoproteínas LDL/sangre , Lipoproteínas LDL/química , Leche Humana/química , Leche Humana/metabolismo , Monocitos/química , Peroxidasa/sangre , Peroxidasa/química , Unión Proteica , Propiedades de Superficie
14.
Ter Arkh ; 93(7): 753-762, 2021 Jul 23.
Artículo en Ruso | MEDLINE | ID: mdl-36286725

RESUMEN

AIM: To analyze the results of treatment in patients with acute myeloid leukemia (AML) within protocols AML-17 and modified AML-17 (mOML-17) as part of two consecutive pilot studies in order to develop the best treatment strategy for AML patients aged below 60 years. MATERIALS AND METHODS: The study included 89 AML patients who were aged below 60 years and received treatment within the AML-17 and mOML-17 protocols. Cytogenetic and molecular genetic studies were performed in all patients. The presence of mutations in the FLT3, NPM1, CEBPa genes was assessed by fragment analysis. 35 patients underwent a study for mutTP53, mutRUNX1 using next generation sequencing (NGS). The minimum residual population of tumor cells was evaluated by multicolor flow cytometry. Statistical analysis was performed using the procedures of the SAS 9.3 package. RESULTS: Complete remission (CR) was achieved in 89.7% of patients treated with intensive chemotherapy (CT) courses and in 52.4% of patients treated with low-dose CT courses. 8.8% of intensively treated patients were refractory to therapy, and 38% did not respond to low-dose exposure. The early mortality rate was 3%. The overall survival and disease-free 3-year survival for patients included in 2 consecutive studies was were 60% and 67%, respectively. The level of minimal residual disease (MRD) after the first course of induction CT was an important prognostic indicator. The three-year relapse-free survival for patients in whom CR was achieved after the first course of induction CT and in whom MRD was not detected (MRD-negative status was obtained) was 90% compared to 43% for patients who were MRD positive after the first course of induction CT (p=0.00001). CONCLUSION: The key factor that significantly affects the long-term results of therapy is the rate of MRD after the first course of induction CT.


Asunto(s)
Trasplante de Células Madre Hematopoyéticas , Leucemia Mieloide Aguda , Humanos , Persona de Mediana Edad , Quimioterapia de Inducción , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/genética , Neoplasia Residual/tratamiento farmacológico , Proteínas Nucleares/genética , Proteínas Nucleares/uso terapéutico , Pronóstico , Estudios Retrospectivos
15.
Ter Arkh ; 93(7): 763-769, 2021 Jul 23.
Artículo en Ruso | MEDLINE | ID: mdl-36286726

RESUMEN

BACKGROUND: LiFraumeni syndrome (LFS) is a rare, autosomal dominant, hereditary disorder that is characterized by an increased risk for certain types of cancer, acute lymphoblastic leukemia (ALL), particularly. Germline TP53 mutations are associated with LFS. Genetic counseling and follow-up is essential for patients with LFS and their relatives. Special therapeutic approaches are needed for treatment of oncological disease in these patients. The article presents a series of clinical cases of patients with ALL and SLF, considers general issues of diagnosis and treatment of adult patients with this hereditary genetic syndrome. AIM: Describe clinical observations of patients with acute lymphoblastic leukemia (ALL) and LFS and consider general issues of diagnosis and treatment of adult patients with LFS and ALL. MATERIALS AND METHODS: TP53 gene mutations were screened using Sanger sequencing in 180 de novo patients with Ph-negative (B- and T-cell) and Ph-positive ALL treated by Russian multicenter protocols (ALL-2009, ALL-2012, ALL-2016) at the National Research Center for Hematology, Moscow, Russia, and at the hematology departments of regional clinics of Russia (multicenter study participants). RESULTS: TP53 gene mutations were found in 7.8% (n=14) of de novo ALL patients. In patients, whose biological material was available TP53 gene mutational status was determined in non-tumor cells (bone marrow and peripheral blood during remission, bone marrow samples after allogeneic hematopoietic stem cells transplantation and in tissue of non-hematopoietic origin) for discriminating germline mutations. The analysis included 5 patients (out of 14 with TP53 mutations), whose non-tumor biological material was available for research. Germline status was confirmed in 4 out of 5 B-cell ALL (n=3), T-cell ALL (n=1) investigated patients. CONCLUSION: Practical value of the research is the observation that the greater part of TP53 gene mutations in patients with Ph-negative B-cell ALL are germinal and associated with LFS.


Asunto(s)
Síndrome de Li-Fraumeni , Leucemia-Linfoma Linfoblástico de Células Precursoras , Adulto , Humanos , Síndrome de Li-Fraumeni/diagnóstico , Síndrome de Li-Fraumeni/genética , Síndrome de Li-Fraumeni/terapia , Genes p53/genética , Predisposición Genética a la Enfermedad , Mutación de Línea Germinal , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia
16.
Ter Arkh ; 92(7): 31-42, 2020 Sep 01.
Artículo en Ruso | MEDLINE | ID: mdl-33346443

RESUMEN

ISSUE: The study of activating mutations (NRAS,KRAS,FLT3,JAK2,CRLF2genes) of RAS/RAF/MEK/ERK and JAK/STAT signaling pathways in B-cell acute lymphoblastic leukemia (B-ALL) in adult patients which are included in Russian multicenter clinical trials. MATERIALS AND METHODS: Within the multicenter study there were 119 adult patients included withde novoB-ALL. The study was considered as prospective and retrospective. The group withBCR-ABL1-negative B-ALL consisted of up to 93 patients (45 male and 48 female, at the age of 17 to 59, the median age 31), they were treated according to the protocols ALL-2009, ALL-2016. The median follow-up lasted for 19 months (1119). The group withBCR-ABL1-positive B-ALL with up to 26 patients (10 male and 16 female, at the age of 23 to 78, the median age 34 years) was included in the study as well. The treatment was carried out according to the protocols ALL-2009 and ALL-2012 in combination with tyrosine kinase inhibitors. The median follow-up lasted for 23 months (4120). The molecular analysis of activating mutations inNRAS,KRASgenes (RAS/RAF/MEK/ERK signaling pathway) andJAK2,CRLF2genes (JAK/STAT signaling cascade) was performed via Sanger sequencing. The internal tandem duplications (ITDs) inFLT3gene were studied by fragment analysis. The evaluation of CRLF2 expression was fulfilled via flow cytometry. RESULTS: Activating mutations inNRAS,KRAS,FLT3genes were found in 22 (23.6%) patients withBCR-ABL1-negative B-ALL. In total, 23 mutations were revealed in theNRAS(n=9),KRAS(n=12), andFLT3(n=2) genes, according to statistics that was significantly more frequent than withBCR-ABL1-positive B-ALL, these genes mutations were not identified in patients (p=0.007). The frequency of mutations detection inKRASandNRASgenes in patients withBCR-ABL1-negative B-ALL was comparable as 12.9% (12 of 93) to 9.7% (9 of 93), respectively (p=0.488). One patient was simultaneously revealed 2 mutations in theKRASgene (in codons 13 and 61).FLT3-ITD mutations were detected in 3.5% (2 of 57) cases ofBCR-ABL1-negative B-ALL. In patients withBCR-ABL1-positive B-ALLFLT3-ITD mutations were not assessed. Violations in the JAK/STAT signaling cascade were detected in 4 (4.3%) patients withBCR-ABL1-negative B-ALL. They were represented by the missense mutations ofJAK2gene (n=3) and the overexpression of CRLF2 (n=2); in one patient were detected the overexpression of CRLF2 and a mutation inJAK2gene simultaneously. No mutations were found inCRLF2gene. In patients withBCR-ABL1-positive B-ALL noJAK2mutations were detected. As long as analyzing demographic and clinical laboratory parameters between groups of patients with and without mutations, there were no statistically significant differences obtained. In the analyzed groups of patients, long-term therapy results did not differentiate according to the mutations presence inNRAS,KRAS,FLT3,JAK2genes. Also, substantive differences were not shown in the rate of the negative status achievement of the minimum residual disease between patients with and without activating mutations in the control points of the protocol (on the 70th, 133rd and 190th days). CONCLUSION: NRAS,KRAS,FLT3,JAK2activating mutations do not affect the long-term results of the therapy and the rate of the negative status achievement of the minimum residual disease in patients withBCR-ABL1-negative B-ALL treated by the Russian multicenter clinical trials.


Asunto(s)
Quinasas de Proteína Quinasa Activadas por Mitógenos , Adulto , Femenino , Humanos , Masculino , Mutación , Estudios Prospectivos , Estudios Retrospectivos , Federación de Rusia
17.
Appl Opt ; 59(34): 10902-10911, 2020 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-33361911

RESUMEN

We present an experimental examination of iridium and boron carbide thin-film coatings for the purpose of fabricating x-ray optics. We use a combination of x-ray reflectometry and x-ray photoelectron spectroscopy to model the structure, composition, density, thickness, and micro-roughness of the thin films. We demonstrate in our analyses how the two characterization techniques are complementary, and from this we derive that an overlayer originating from atmospheric contamination with a thickness between 1.0-1.6 nm is present on the surface. The magnetron sputtered iridium films are measured to have a density of 22.4g/cm3. The boron carbide film exhibits a change in chemical composition in the top ∼2nm of the film surface when exposed to the ambient atmosphere. The chemical reaction occurring on the surface is due to an incorporation of oxygen and hydrogen present in the ambient atmosphere. Lastly, we present a correlation between the absorption edges and the emission lines exhibited by the thin films in an energy range from 50-800 eV and the impact on the reflectivity performance due to contamination in thin films.

18.
J Chem Phys ; 153(19): 194501, 2020 Nov 21.
Artículo en Inglés | MEDLINE | ID: mdl-33218241

RESUMEN

Combining results from impedance spectroscopy and oscillatory shear rheology, the present work focuses on the relation between the mass and charge flows and on how these are affected by the H-bonding in viscous ionic liquids (ILs). In particular, we compare the relaxational behaviors of the paradigmatic IL 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) and its OH-functionalized counterpart 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (OHEMIM-TFSI). Our results and their analysis demonstrate that the presence of cationic OH-groups bears a strong impact on the overall dynamics of OHEMIM-TFSI, although no signatures of suprastructural relaxation modes could be identified in their dielectric and mechanical responses. To check whether at the origin of this strong variation is the H-bonding or merely the difference between the corresponding cation sizes (controlling both the hydrodynamic volume and the inter-charge distance), the present study includes 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (PMIM-TFSI), mixtures of EMIM-TFSI and PMIM-TFSI with lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI), and mixtures of OHEMIM-TFSI with PMIM-TFSI. Their investigation clearly reveals that the dynamical changes induced by H-bonding are significantly larger than those that can be attributed to the change in the ion size. Moreover, in the mixtures of OHEMIM-TFSI with PMIM-TFSI, a dilution of the OH-groups leads to strong deviations from ideal mixing behavior, thus highlighting the common phenomenological ground of hydroxy-functionalized ILs and other H-bonded liquids.

19.
Appl Opt ; 59(32): 9912-9923, 2020 Nov 10.
Artículo en Inglés | MEDLINE | ID: mdl-33175762

RESUMEN

The interference of the beams reflected from a combination of two deployed cube-corner reflectors with a special interference phase-shifting coating is considered. It is shown that in this case a beam with an axisymmetric polarization structure appears. Particular attention is paid to the various optical vortices, which are formed if polarization of light is circular. It is proposed to use this system to create a retroreflective interferometer, in which the spatial polarization structure sensitivity changes due to the path difference between the beams, reflected from two different corner-cube reflectors. It is installed such that the position of the plane of vector E oscillations rotates with azimuth variation in the transverse plane, while at different angular distances from the beam axis this rotation can occur in opposite directions, i.e., we observed a counter-twisted polarization structure, useful for manipulating small particles.

20.
Opt Express ; 28(17): 25444-25459, 2020 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-32907065

RESUMEN

We report on the first injection-seeded nanosecond Ti:Sapphire laser that demonstrates a stable single-longitudinal-mode operation with no feedback loop for active cavity stabilization. The short cavity generates 6-mJ transform-limited pulses at a wavelength of 807 nm and with a slope efficiency of 43%. An intracavity dispersive prism makes a novel cavity design for injection-seeded lasers and provides pre-selection of the emission wavelength. In support of these experiments, we perform numerical simulations that include extra cavity losses. The simulation results are in good agreement with the outcome of the experiment and reveal the formation scenario of the laser mode.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...