Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 82
Filtrar
Mais filtros

Bases de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Molecules ; 29(10)2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38792042

RESUMO

1,3,5-Tris-(α-naphthyl)benzene is an organic non-electrolyte with notable stability of an amorphous phase. Its glassy and supercooled liquid states were previously studied by spectroscopic and calorimetric methods. Despite the continuing interest in its amorphous state and, particularly, vapor-deposited glasses, the thermodynamic parameters of the vaporization of 1,3,5-tris-(α-naphthyl)benzene have not been obtained yet. Likewise, the reliable evaluation of the thermodynamic parameters of fusion below the melting point, required to establish the thermodynamic state of its glass, is still an unsolved problem. In this work, the heat capacities of crystalline and liquid phases, the temperature dependence of the saturated vapor pressures, fusion and vaporization enthalpies were determined using differential and fast scanning calorimetry and were verified using the estimates based on solution calorimetry. The structural features of 1,3,5-tris-(α-naphthyl)benzene are discussed based on the computations performed and the data on the molecular refractivity. The consistency between the values obtained by independent techniques was demonstrated.

2.
Molecules ; 28(20)2023 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-37894506

RESUMO

In this work, we present a comprehensive study of the thermodynamic properties of 3-and 4-ethoxyacetanilides. The heat capacities in crystalline, liquid, and supercooled liquid states from 80 to 475 K were obtained using adiabatic, differential scanning (DSC), and fast scanning (FSC) calorimetries. The fusion enthalpies at Tm were combined from DSC measurement results and the literature data. The fusion enthalpies at 298.15 K were evaluated in two independent ways: adjusted according to Kirchhoff's law of thermochemistry, and using Hess' law. For the latter approach, the enthalpies of the solution in DMF in crystalline and supercooled liquid states were derived. The values obtained by the two methods are consistent with each other. The standard thermodynamic functions (entropy, enthalpy, and Gibbs energy) between 80 and 470 K were calculated.

3.
Opt Express ; 30(19): 34935-34937, 2022 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-36242497

RESUMO

We correct values and figures for the resolution of the spectrometer, as proposed in [Opt. Express25, 31840 (2017)10.1364/OE.25.031840OPEXFF1094-4087]. The new results take into account previously unknown, incoherent phase fluctuations, caused by the polycapillary lens (PCL), and estimate the realistic performance of the instrument.

4.
Opt Lett ; 47(6): 1331-1334, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-35290306

RESUMO

A lamellar multilayer grating in a conical diffraction mounting was proposed as a beam splitter for X-ray free-electron lasers. Theoretical calculations demonstrated that the distribution of diffraction efficiency can be adjusted by optimizing the groove depth or d-spacing. A Cr/C multilayer lamellar grating with a line density of approximately 2500 L/mm was fabricated. The performance of the element was measured in the Optics Beamline PM-1 (BESSY-II) at an energy of 1500 eV. A five-order diffraction pattern was recognized, and the diffraction efficiencies of the -/+first-order were approximately 12.6 and 4.4%, respectively. The asymmetric distribution of diffraction efficiency can be caused by the different sidewall angles of the grating groove.

5.
Phys Rev Lett ; 128(1): 018004, 2022 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-35061462

RESUMO

Self-organization phenomena in ensembles of self-propelled particles open pathways to the synthesis of new dynamic states not accessible by traditional equilibrium processes. The challenge is to develop a set of principles that facilitate the control and manipulation of emergent active states. Here, we report that dielectric rolling colloids energized by a pulsating electric field self-organize into alternating square lattices with a lattice constant controlled by the parameters of the field. We combine experiments and simulations to examine spatiotemporal properties of the emergent collective patterns and investigate the underlying dynamics of the self-organization.We reveal the resistance of the dynamic lattices to compression and expansion stresses leading to a hysteretic behavior of the lattice constant. The general mechanism of pattern synthesis and control in active ensembles via temporal modulation of activity can be applied to other active colloidal systems.

6.
Soft Matter ; 18(45): 8641-8646, 2022 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-36342339

RESUMO

Suspensions of microswimmers in liquid crystals demonstrate remarkably complex dynamics and serve as a model system for studying active nematics. So far, experimental realization of microswimmers suspended in liquid crystalline media has relied on biological microorganisms that impose strict limitations on the compatible media and makes it difficult to regulate activity. Here, we demonstrate that acoustically powered bubble microswimmers can efficiently self-propel in a lyotropic liquid crystal. The velocity of the swimmers is controlled by the amplitude of the acoustic field. Histograms of swimming directions with respect to the local nematic field reveal a bimodal distribution: the swimmers tend to either fully align with or swim perpendicular to the director field of the liquid crystal, occasionally switching between these two states. The bubble-induced streaming from a swimmer locally melts the liquid crystal and produces topological defects at the tail of the swimmer. We show that the defect proliferation rate increases with the angle between the swimmer's velocity and the local orientation of the director field.


Assuntos
Cristais Líquidos , Cristais Líquidos/química , Modelos Biológicos , Natação , Acústica , Suspensões
7.
Int J Mol Sci ; 23(19)2022 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-36233301

RESUMO

S100 proteins are multifunctional calcium-binding proteins of vertebrates that act intracellularly, extracellularly, or both, and are engaged in the progression of many socially significant diseases. Their extracellular action is typically mediated by the recognition of specific receptor proteins. Recent studies indicate the ability of some S100 proteins to affect cytokine signaling through direct interaction with cytokines. S100P was shown to be the S100 protein most actively involved in interactions with some four-helical cytokines. To assess the selectivity of the S100P protein binding to four-helical cytokines, we have probed the interaction of Ca2+-bound recombinant human S100P with a panel of 32 four-helical human cytokines covering all structural families of this fold, using surface plasmon resonance spectroscopy. A total of 22 cytokines from all families of four-helical cytokines are S100P binders with the equilibrium dissociation constants, Kd, ranging from 1 nM to 3 µM (below the Kd value for the S100P complex with the V domain of its conventional receptor, receptor for advanced glycation end products, RAGE). Molecular docking and mutagenesis studies revealed the presence in the S100P molecule of a cytokine-binding site, which overlaps with the RAGE-binding site. Since S100 binding to four-helical cytokines inhibits their signaling in some cases, the revealed ability of the S100P protein to interact with ca. 71% of the four-helical cytokines indicates that S100P may serve as a poorly selective inhibitor of their action.


Assuntos
Proteínas de Ligação ao Cálcio , Cálcio , Citocinas , Cálcio/metabolismo , Cálcio da Dieta , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Transporte/metabolismo , Citocinas/metabolismo , Humanos , Fatores Imunológicos , Simulação de Acoplamento Molecular , Proteínas de Neoplasias/metabolismo , Ligação Proteica , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Proteínas S100/metabolismo
8.
Int J Mol Sci ; 23(24)2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-36555597

RESUMO

Tumor necrosis factor (TNF) inhibitors (anti-TNFs) represent a cornerstone of the treatment of various immune-mediated inflammatory diseases and are among the most commercially successful therapeutic agents. Knowledge of TNF binding partners is critical for identification of the factors able to affect clinical efficacy of the anti-TNFs. Here, we report that among eighteen representatives of the multifunctional S100 protein family, only S100A11, S100A12 and S100A13 interact with the soluble form of TNF (sTNF) in vitro. The lowest equilibrium dissociation constants (Kd) for the complexes with monomeric sTNF determined using surface plasmon resonance spectroscopy range from 2 nM to 28 nM. The apparent Kd values for the complexes of multimeric sTNF with S100A11/A12 estimated from fluorimetric titrations are 0.1-0.3 µM. S100A12/A13 suppress the cytotoxic activity of sTNF against Huh-7 cells, as evidenced by the MTT assay. Structural modeling indicates that the sTNF-S100 interactions may interfere with the sTNF recognition by the therapeutic anti-TNFs. Bioinformatics analysis reveals dysregulation of TNF and S100A11/A12/A13 in numerous disorders. Overall, we have shown a novel potential regulatory role of the extracellular forms of specific S100 proteins that may affect the efficacy of anti-TNF treatment in various diseases.


Assuntos
Receptores do Fator de Necrose Tumoral , Proteínas S100 , Receptores do Fator de Necrose Tumoral/metabolismo , Proteína S100A12 , Inibidores do Fator de Necrose Tumoral , Fator de Necrose Tumoral alfa/metabolismo
9.
J Synchrotron Radiat ; 28(Pt 5): 1620-1630, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34475309

RESUMO

FinEstBeAMS (Finnish-Estonian Beamline for Atmospheric and Materials Sciences) is a multidisciplinary beamline constructed at the 1.5 GeV storage ring of the MAX IV synchrotron facility in Lund, Sweden. The beamline covers an extremely wide photon energy range, 4.5-1300 eV, by utilizing a single elliptically polarizing undulator as a radiation source and a single grazing-incidence plane grating monochromator to disperse the radiation. At photon energies below 70 eV the beamline operation relies on the use of optical and thin-film filters to remove higher-order components from the monochromated radiation. This paper discusses the performance of the beamline, examining such characteristics as the quality of the gratings, photon energy calibration, photon energy resolution, available photon flux, polarization quality and focal spot size.

10.
Opt Express ; 29(9): 13416-13427, 2021 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-33985075

RESUMO

The d-spacing of the multilayer lamellar grating was theoretically optimized to improve the energy resolution and maintain a high efficiency. Based on the study of the growth behavior of Mo/Si multilayer on the lamellar grating under different sputtering pressures, Ar gas pressure of 1 mTorr was selected, which can fabricate the multilayer with lower roughness and a good replication of the groove shape. An absolute diffraction efficiency of 25.6% and a Cff factor of 1.79 were achieved for the -1st order of the Mo/Si lamellar multilayer grating at an energy of 1700 eV.

11.
Chemistry ; 27(35): 9180-9192, 2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-33871132

RESUMO

Hydroxyisophthalic acids are valuable polytopic ligands for the design of functional materials based on coordination polymers due to the variety of charges and coordination modes they possess. Herein, we describe the synthesis, thermal stability, nonlinear optical (NLO) and spectroscopic properties of five novel coordination compounds, [K2 L(H2 O)2 ], [MgL(H2 O)2 ] ⋅ 3H2 O, [CaL(H2 O)3 ], [SrL(H2 O)3 ] ⋅ H2 O, [BaL(H2 O)(H2 O)5 ], and one salt, (NH4 )2 L ⋅ 2H2 O, with 4,5,6-trihydroxyisophthalic acid (H2 L), which has not been tested in assembling crystalline coordination networks before. The peculiarities of the structural organization of the compounds were analyzed and compared with those for other hydroxyisophthalates. The coordination properties of hydroxyisophthalic acids were studied from the topological point of view, and a comparative topological analysis of coordination and H-bonded networks was performed. Structural correlations revealed in this study could be useful for the design of hydroxyisophthalate-based coordination networks, including porous metal-organic frameworks, proton conductors, and NLO materials.

12.
J Synchrotron Radiat ; 27(Pt 1): 75-82, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31868739

RESUMO

In this work, the refractive index of beryllium in the photon energy range 20.4-250 eV was experimentally determined. The initial data include measurements of the transmittance of two free-standing Be films with thicknesses of 70 nm and 152 nm, as well as reflectometric measurements of similar films on a substrate. Measurements were carried out at the optics beamline of the BESSY II synchrotron radiation source. The absorption coefficient ß was found directly from the transmission coefficient of the films, and the real part of the polarizability δ was calculated from the Kramers-Kronig relations. A comparison is carried out with results obtained 20 years ago at the ALS synchrotron using a similar methodology.

13.
Opt Express ; 28(2): 821-845, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32121805

RESUMO

The problem of X-ray diffraction from multilayer-coated blazed diffraction gratings is analyzed. Invalidity of the conventional condition of maximal diffraction efficiency observed in previous experiments is explained theoretically. This is attributed to two factors: contribution of anti-blaze facets to diffraction efficiency and effect of strongly asymmetric diffraction. We demonstrate that a proper choice of the multilayer d-spacing allows to design grating with the diffraction efficiency close to the maximal possible one throughout the tender X-ray range (E∼1-5 keV). An optimization procedure is suggested for the first time to choose the optimal grating parameters and the operation diffraction order to obtain a high fix-focus constant and high diffraction efficiency simultaneously in a wide spectral range.

14.
Langmuir ; 36(25): 6957-6962, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-31756110

RESUMO

Active magnetic colloids are capable of rich collective behavior and complex self-organization. The interplay between short- and long-range interactions taking place away from equilibrium often results in a spontaneous formation of localized dynamic microstructures. Here we report a method for guided self-assembly and control of self-organized colloidal vortices emerging in a ferromagnetic particle ensemble energized by a uniaxial alternating (ac) magnetic field. The structure of a vortex composed of rolling magnetic particles can be stabilized and manipulated by means of an additional strongly localized alternating magnetic field provided by a minicoil. By tuning the parameters of the localized field, we effectively control the dimensions and particle number density in the vortex. We find that the roller vortex self-organization is assisted by field-induced magnetic "steering" rather than magnetic field gradients and is only possible while the system is in the active (magnetic rollers) state. We demonstrate that parameters of the emergent vortex are efficiently tuned by a phase shift between alternating magnetic fields. The method for assisted self-organization of rolling magnetic colloids into a vortex with on-demand characteristics suggests a new tool for active matter control and manipulation that may lead to a development of new approaches toward the guided microscopic transport in active particle systems.

15.
Acta Haematol ; 143(2): 131-139, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31597157

RESUMO

T-cell acute lymphoblastic leukemia (T-ALL) is a rare disease usually treated with intensive, high-dose consolidation chemotherapy followed by an allotransplant in a substantial number of patients. The data of the RALL-2009 study on 125 adult T-ALL patients suggest that similar total chemotherapy doses given less intensively over a longer interval without interruptions and with an auto- rather than an allotransplant produce outcomes like current more intensive protocols and an allotransplant: 9-year cumulative incidence of relapse (CIR), leukemia-free survival (LFS), and survival were 24% (95% CI 16-33%), 70% (95% CI 59-79%) and 62% (95% CI 51-72%). In a landmark analysis, subjects achieving a complete remission and receiving an autotransplant had a lower 9-year CIR (9% [95% CI 2-22%] vs. 29% [95% CI 16-43%]; p = 0.0076) and better LFS (91% [95% CI 79-98%] vs. 58% [95% CI 41-74%]; p = 0.0009) and survival (92% [95% CI 77-99%] vs. 60% [95% CI 44-77%]; p = 0.001) compared with subjects not receiving an autotransplant. In a multivariate analysis, white blood cells ≥100 × 109/L at study entry were significantly associated with worse LFS (HR = 2.842 [95% CI 1.131-7.143]; p = 0.0263) and survival (HR = 6.085 [95% CI 1.918-19.3]; p = 0.0022) because of more early deaths (HR = 2.42 [95% CI 1.04-5.67]; p = 0.041). Receiving an autotransplant correlated with a lower CIR (HR = 0.23 [95% CI 0.07-0.73]; p = 0.0136) and better LFS (HR = 0.27 [95% CI 0.08-0.85]; p = 0.0256) and survival (HR = 0.158 [95% CI 0.045-0.550]; p = 0.0037).


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Transplante de Células-Tronco Hematopoéticas , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Adolescente , Adulto , Intervalo Livre de Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Leucemia-Linfoma Linfoblástico de Células Precursoras/mortalidade , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Modelos de Riscos Proporcionais , Recidiva , Indução de Remissão , Taxa de Sobrevida , Transplante Autólogo , Resultado do Tratamento , Adulto Jovem
16.
Int J Mol Sci ; 21(24)2020 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-33322098

RESUMO

Interferon-ß (IFN-ß) is a pleiotropic cytokine used for therapy of multiple sclerosis, which is also effective in suppression of viral and bacterial infections and cancer. Recently, we reported a highly specific interaction between IFN-ß and S100P lowering IFN-ß cytotoxicity to cancer cells (Int J Biol Macromol. 2020; 143: 633-639). S100P is a member of large family of multifunctional Ca2+-binding proteins with cytokine-like activities. To probe selectivity of IFN-ß-S100 interaction with respect to S100 proteins, we used surface plasmon resonance spectroscopy, chemical crosslinking, and crystal violet assay. Among the thirteen S100 proteins studied S100A1, S100A4, and S100A6 proteins exhibit strictly Ca2+-dependent binding to IFN-ß with equilibrium dissociation constants, Kd, of 0.04-1.5 µM for their Ca2+-bound homodimeric forms. Calcium depletion abolishes the S100-IFN-ß interactions. Monomerization of S100A1/A4/A6 decreases Kd values down to 0.11-1.0 nM. Interferon-α is unable of binding to the S100 proteins studied. S100A1/A4 proteins inhibit IFN-ß-induced suppression of MCF-7 cells viability. The revealed direct influence of specific S100 proteins on IFN-ß activity uncovers a novel regulatory role of particular S100 proteins, and opens up novel approaches to enhancement of therapeutic efficacy of IFN-ß.


Assuntos
Cálcio/metabolismo , Interferon beta/metabolismo , Proteínas S100/metabolismo , Sequência de Aminoácidos , Cálcio/química , Proteínas de Ligação ao Cálcio/química , Proteínas de Ligação ao Cálcio/metabolismo , Doenças Cardiovasculares/metabolismo , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Dimerização , Humanos , Cinética , Células MCF-7 , Modelos Químicos , Simulação de Acoplamento Molecular , Proteínas de Neoplasias/química , Proteínas de Neoplasias/metabolismo , Neoplasias/metabolismo , Doenças do Sistema Nervoso/metabolismo , Ligação Proteica , Conformação Proteica/efeitos dos fármacos , Proteína A6 Ligante de Cálcio S100/química , Proteína A6 Ligante de Cálcio S100/metabolismo , Proteína A4 de Ligação a Cálcio da Família S100/química , Proteína A4 de Ligação a Cálcio da Família S100/metabolismo , Proteínas S100/química , Alinhamento de Sequência , Ressonância de Plasmônio de Superfície
17.
BMC Bioinformatics ; 20(Suppl 4): 119, 2019 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-30999858

RESUMO

BACKGROUND: The search for molecular biomarkers of early-onset colorectal cancer (CRC) is an important but still quite challenging and unsolved task. Detection of CpG methylation in human DNA obtained from blood or stool has been proposed as a promising approach to a noninvasive early diagnosis of CRC. Thousands of abnormally methylated CpG positions in CRC genomes are often located in non-coding parts of genes. Novel bioinformatic methods are thus urgently needed for multi-omics data analysis to reveal causative biomarkers with a potential driver role in early stages of cancer. METHODS: We have developed a method for finding potential causal relationships between epigenetic changes (DNA methylations) in gene regulatory regions that affect transcription factor binding sites (TFBS) and gene expression changes. This method also considers the topology of the involved signal transduction pathways and searches for positive feedback loops that may cause the carcinogenic aberrations in gene expression. We call this method "Walking pathways", since it searches for potential rewiring mechanisms in cancer pathways due to dynamic changes in the DNA methylation status of important gene regulatory regions ("epigenomic walking"). RESULTS: In this paper, we analysed an extensive collection of full genome gene-expression data (RNA-seq) and DNA methylation data of genomic CpG islands (using Illumina methylation arrays) generated from a sample of tumor and normal gut epithelial tissues of 300 patients with colorectal cancer (at different stages of the disease) (data generated in the EU-supported SysCol project). Identification of potential epigenetic biomarkers of DNA methylation was performed using the fully automatic multi-omics analysis web service "My Genome Enhancer" (MGE) (my-genome-enhancer.com). MGE uses the database on gene regulation TRANSFAC®, the signal transduction pathways database TRANSPATH®, and software that employs AI (artificial intelligence) methods for the analysis of cancer-specific enhancers. CONCLUSIONS: The identified biomarkers underwent experimental testing on an independent set of blood samples from patients with colorectal cancer. As a result, using advanced methods of statistics and machine learning, a minimum set of 6 biomarkers was selected, which together achieve the best cancer detection potential. The markers include hypermethylated positions in regulatory regions of the following genes: CALCA, ENO1, MYC, PDX1, TCF7, ZNF43.


Assuntos
Biomarcadores Tumorais/genética , Neoplasias Colorretais/genética , Metilação de DNA/genética , Retroalimentação Fisiológica , Transdução de Sinais/genética , Sítios de Ligação/genética , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/patologia , Ilhas de CpG/genética , Epigênese Genética , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Fatores de Transcrição/metabolismo
18.
Am J Transplant ; 19(7): 1941-1954, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30748092

RESUMO

Acute graft-versus-host disease (aGVHD) remains a barrier to the success of allogeneic hematopoietic stem cell transplantation (HSCT). Previously, we demonstrated that CC-chemokine receptor 7 (CCR7) is critical for aGVHD pathogenesis but dispensable for beneficial graft-versus-leukemia responses. As a result, we evaluated a fully human anti-CCR7-blocking antibody as a new approach to prevent aGVHD in preclinical models. Here we report that antibody R707 is able to block human CCR7 signaling and function in vitro in response to its 2 natural ligands. The antibody was less active against the murine orthologue, however, and failed to substantially limit aGVHD in a standard murine allogeneic HSCT model. Nevertheless, R707 significantly reduced xenogeneic aGVHD induced by human peripheral blood mononuclear cells (PBMCs). R707 limited CD4+ and in particular CD8+ T cell expansion during the period of antibody administration. These effects were transient, however, and T cell numbers recovered after antibody cessation. R707 did not substantially impair the antitumor potential of the PBMC inoculum as antibody-treated mice retained their capacity to reject a human acute myeloid leukemia cell line. Collectively, these data indicate for the first time that an antibody directed against CCR7 might represent a viable new approach for aGVHD prevention.


Assuntos
Anticorpos Monoclonais/farmacologia , Doença Enxerto-Hospedeiro/imunologia , Doença Enxerto-Hospedeiro/prevenção & controle , Leucócitos Mononucleares/imunologia , Receptores CCR7/imunologia , Linfócitos T/imunologia , Doença Aguda , Animais , Anticorpos Monoclonais/imunologia , Doença Enxerto-Hospedeiro/genética , Transplante de Células-Tronco Hematopoéticas , Xenoenxertos , Humanos , Camundongos , Receptores CCR7/genética , Linfócitos T/transplante , Doadores de Tecidos , Transplante Homólogo
19.
J Synchrotron Radiat ; 26(Pt 5): 1782-1789, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31490170

RESUMO

A fabrication method comprising near-field holography (NFH) with an electron beam lithography (EBL)-written phase mask was developed to fabricate soft X-ray varied-line-spacing gratings (VLSGs). An EBL-written phase mask with an area of 52 mm × 30 mm and a central line density greater than 3000 lines mm-1 was used. The introduction of the EBL-written phase mask substantially simplified the NFH optics for pattern transfer. The characterization of the groove density distribution and diffraction efficiency of the fabricated VLSGs indicates that the EBL-NFH method is feasible and promising for achieving high-accuracy groove density distributions with corresponding image properties. Vertical stray light is suppressed in the soft X-ray spectral range.

20.
Opt Express ; 27(12): 16833-16846, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31252903

RESUMO

The optimized design of multilayer-coated blazed gratings (MLBG) for high-flux tender X-ray monochromators was systematically studied by numerical simulations. The resulting correlation between the multilayer d-spacing and grating blaze angle significantly deviated from the one predicted by conventional equations. Three high line density gratings with different blaze angles were fabricated and coated by the same Cr/C multilayer. The MLBG with an optimal blaze angle of 1.0° showed a record efficiency reaching 60% at 3.1 keV and 4.1 keV. The measured efficiencies of all three gratings were consistent with calculated results proving the validity of the numerical simulation and indicating a more rigorous way to design the optimal MLBG structure.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA