Resonance Studies Research Articles

Resonant Inelastic Soft X-ray Scattering Study of Co-Doped Maghemite Nanoparticles.

Cobalt ferrite nanoparticles have been attracting considerable interest in the recent years because of the large number of potential applications, including magnetic storage, magnetic fluid hyperthermia and as contrast agents for magnetic resonance imaging. Physical properties of this class of materials depend critically on a number of parameters, including crystallinity, stoichiometry and cation distribution. In this work we have performed a Resonant Inelastic soft X-ray Scattering (RIXS) study on a series of 5 nm cobalt-doped maghemite nanoparticles to obtain direct quantitative information on cation distribution as a function of cobalt doping. We found that the distribution of divalent cobalt is stable in the investigated doping range and slightly different from that of bulk, stoichiometric cobalt ferrite. These results confirm that cobalt doping can be used to finely tune the magnetic properties of nanostructured ferrites without modifying their structural integrity.

Магнітно-резонансне та коронарографічне дослідження серця щурів за штучного гіпобіозу

Магнітно-резонансне та коронарографічне дослідження серця щурів за штучного гіпобіозу

Diameter dependent doping in horizontally aligned high-density N-doped SWNT arrays

We reported the growth of horizontally aligned nitrogen-doped single-walled carbon nanotubes (SWNTs) on quartz substrates. The synthesized SWNTs were comprehensively characterized at the single nanotube level. Owing to the highly aligned nature of the nanotubes, we were able to investigate the diameter dependent doping mechanism through systematic resonant Raman spectroscopy studies. Other than the formerly found narrowing effect by N-doping, we proposed that the nanotube diameter affects the introduction of N atoms into the carbon lattice in an elaborate way. The obtained doping level increased along with the nanotube diameter but lost the increasing trend when the diameter became larger and experienced a slight decrease after reaching the local peak value. These insights about the heteroatom doping into the carbon nanotubes could benefit the development of the carbon nanotube based functional materials and extend their application in a broad range of areas.

P407Epicardial fat in patients with diabetes and coronary artery disease: a comprehensive study of cardiovascular magnetic resonance, genes expressions and corresponding serum cytokines.

P407Epicardial fat in patients with diabetes and coronary artery disease: a comprehensive study of cardiovascular magnetic resonance, genes expressions and corresponding serum cytokines.

CHARACTERIZATION AND HYPOGLYCEMIC STUDY OF ISOLATED NATURAL POLYMER FROM THE STEM OF MANILKARA HEXANDRA (ROXB.) DUBARD

Objective: In the present study, the isolated natural polymer from the stem of Manilkara hexandra and their physiochemical parameters were investigated. It is further involved in hypoglycemic studies.
 Methods: The gum exudates were screened for phytochemicals, physicochemically analyzed for solubility, pH, total ash, moisture content, acid insoluble ash, water soluble ash, sulfated ash, flow property, and it is characterized by Fourier Transform Infrared analysis (FT-IR), Scanning Electron Microscope (SEM), X-ray diffraction analysis (XRD), Nuclear Magnetic Resonance (NMR) studies (13Carbon and 1Proton) and it was examined in vitro studies by hypoglycaemic activity.
 Results: The isolated gum extracted from the stem of Manilkara hexandra (Roxb.) Dubard ash values were found to be low. The gum is found to be hygroscopic in nature due to its high moisture content (0.9131±0.03). Fourier Transform Infrared (FT-IR) spectra show relevant functional groups for gum, which is further confirmed by resonance spectral studies. The X-ray diffraction (XRD) pattern shows that the gum is amorphous as well as crystalline in nature. Scanning Electron Microscope (SEM) image confirms that the gum particles have irregular size and shape. Sugar composition analysis by Thin Layer Chromatography indicated the presence of rhamnose, arabinose. The in vitro study of hypoglycemic activity shows the best report compared with the standard. The experimental evidence offers scope to use this natural polymer in the food and pharmaceutical industry.
 Conclusion: The isolated natural polymer shows good result in hypoglycemic studies compared with standard.

Resonance studies using the contour deformation method in the complex momentum plane

A contour deformation method (CDM) in the complex momentum plane has been successfully extended and implemented to probe resonances in atomic and molecular systems. Specifically, solution of the Schrödinger equation is performed in momentum space with momentum deformed on a contour in the complex plane. The bound, resonant, and complex continuum states could be directly revealed from the eigenvalues of the Schrödinger equation in the complex momentum plane. The calculations of shape resonances in electron scattering with Na+ in Debye plasmas (one channel), and in the charge transfer process H−(1s2)+Li(1s22s) (12Σ+) →H(1s)+Li−(1s22s2) (22Σ+) (coupled channels) are given as illustrative examples. It is shown that calculated results from CDM agree very well with those extracted from the eigenphase sum of scattering theories. The effectiveness of CDM is also demonstrated by comparing its results with those obtained by the complex rotation scaling and exterior complex scaling methods. The convergence of CDM results can be obtained by increasing the momentum integration region and the number of integration points. The studied examples demonstrate that CDM could be a powerful tool for studies of resonances in complex atomic and molecular systems.

Computer Application of Ultrasound and Nuclear Magnetic Resonance Images for the Anatomical Learning of the Pelvis and the Female Pelvic Floor.

Computer applications have been incorporated as valuable components in teaching, especially thanks to the advancement and innovation of new technologies during the last decades. The implementation of these computer developments in medicine and in the field of medical teaching with different utilities has been a revolution. This is manifested with greater intensity in certain medical specialties and in different areas of medical education, for example in the study of human anatomy, especially in parts of the human body of great complexity such as the pelvis and the pelvic floor of women. New technologies are also important in the use, study and interpretation of radiological tests, including ultrasound and nuclear magnetic resonance. This implies a change in the study and learning techniques of students, resident doctors and specialists in gynecology, radiodiagnosis, urology and many other medical specialties, considering new computer developments as a good alternative or complement to existing teaching methods. For this reason, we consider that computer programs like the one we present in this work can be very useful in the future of education and more specifically in the training of specialists in medicine.

New Z-chalcones obtained from aloe-emodin: Synthesis, characterization and photophysical properties

Three new Z-chalcone derivatives were synthesized under stereoselective conditions by condensation between an aldehyde derivative (prepared from aloe-emodin) and an acetophenone, using potassium hydroxide in dimethyl sulfoxide/H2O at room temperature. The Z configuration of the chalcone derivatives was established by nuclear magnetic resonance (NMR) studies. Photophysical properties related to the UV-Vis absorption/emission spectra and molar extinction coefficients (ε) in different solvents were determined.

О применении метода стробоскопических выборок при изучении квадрупольного возбуждения и квадрупольного резонанса

О применении метода стробоскопических выборок при изучении квадрупольного возбуждения и квадрупольного резонанса

Investigations on structural and spectral properties of undoped and Mn2+ doped SrZn2(PO4)2 nanophosphors for light emitting devices

SrZn2(PO4)2 (SZP) and Mn2+ doped SrZn2(PO4)2 (SZP: Mn) nanophosphors are prepared through solution combustion synthesis at a moderate temperature of 823 K. The nanophosphors are characterized by structural and spectral investigations systematically. X-ray diffraction (XRD) analysis confirms the monoclinic phase of SrZn2(PO4)2 with average crystallite size around 60–65 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the samples have shown irregular morphology. The fundamental vibrational modes of different phosphate groups are confirmed by Fourier transform infrared (FT-IR) spectroscopic analysis. Optical absorption spectrum exhibits Mn2+ characteristic bands are in visible region. Electron paramagnetic resonance (EPR) study describes octahedral environment of Mn2+ ions around the ligands in the host. Photoluminescence (PL) spectra show peaks in blue and yellow–orange region. Commission Internationale de l’Eclairage (CIE) and color correlation temperature (CCT) values indicate that SZP and SZP:Mn nanophosphors are potentially good for solid state lightening and white light emitting diodes (WLEDs).

Structure of Rhoptry Neck Protein 2 is essential for the interaction in vitro with Apical Membrane Antigen 1 in Plasmodium vivax

BackgroundIn several Apicomplexa, the formation of moving junctions (MJs) at the interface between the external membranes of the invading parasite and the host cell is essential for the process of parasite invasion. In Plasmodium falciparum and Toxoplasma gondii, the MJ is composed of the Apical Membrane Antigen 1 (AMA1) and Rhoptry Neck Proteins (RONs) complex; specifically, AMA1 interacts with RON2 during host cell invasion.MethodsRecombinant proteins based on Plasmodium vivax RON2 (A2033-P2100) and its synthetic peptide fragments, one cyclic and one linear, based on PvRON2 (D2035-T2074) were generated and used to evaluate the interaction with P. vivax AMA1 (PvAMA1) by the far western blot, surface plasmon resonance (SPR), and isothermal titration microcalorimetry (ITC) methods. The structural studies of peptides were performed by circular dichroism, and the structural analysis of the complex of PvAMA1 with peptides based on PvRON2 (D2035-T2074) was conducted with small-angle X-ray scattering (SAXS).ResultsSurface plasmon resonance (KD = 23.91 ± 2.078 μmol/L) and ITC (K = 3 × 105 mol/L) studies conclusively showed an interaction between the cyclic peptide based on PvRON2 and PvAMA1-His6. In contrast, the linear peptide and recombinant PvRON2 (GST fusion protein) did not show an interaction with PvAMA1. However, the interaction among recombinant proteins PvRON2.2 and PvAMA1-His6 was possible to show by far western blot.ConclusionsThe results show that the PvRON2 structure, particularly the S–S bond between C2051 and C2063, is determinant for the existence of the interaction between PvAMA1 and PvRON2.

Magnetization and magnetic resonance in sol-gel derived polycrystalline BiFeO3 film

Abstract The structure and magnetic properties of polycrystalline BiFeO3 films grown on glass substrate using Sol-Gel technique have been investigated. X-ray diffraction (XRD) analysis revealed the average grain size of about 21 nm. The root mean square (RMS) surface roughness of about 50 nm has been obtained for the film by using scanning electron microscope (SEM) technique. Ferromagnetic resonance (FMR) studies showed the presence of macroscopic ferromagnetic magnetization and uniaxial out-of-plane magnetic anisotropy. The temperature dependences of the magnetization of BiFeO3 films registered in zero field cooling (ZFC) and field cooling (FC) regimes revealed a spin glass state. The average magnetic crystallite sizes obtained from the magnetizations studies coincide with the values revealed from the structural studies.

Recent applications of the subtracted SRPA approximation

The Second Random Phase Approximation (SRPA) is a natural extension of the Random Phase Approximation obtained by introducing more general excitation operators where two particle-two hole configurations, in addition to the one particle-one hole ones, are considered. Only in the last years, large-scale SRPA calculations, without usually employed approximations have been performed. The SRPA model corrected by a subtraction procedure designed to cure double counting issues and the related instabilities has been recently implemented and applied in the study of different physical cases. We report here on some of the most recent results obtained by using this model. In particular, results on the dipole strength 48Ca and on a systematic study of the isoscalar giant quadrupole resonance in spherical nuclei will be shown and discussed.

Study of baryonic resonances and ρ meson production in the reaction pp → ppπ+π− at 3.5 GeV with HADES

We report on measurements of baryon resonance and ρ meson production in the exclusive pp → ppπ+π− channel at a beam kinetic energy of 3.5 GeV measured with the HADES experimental setup. The differential distributions are compared to Monte Carlo simulations based on a resonance model assuming an incoherent sum of contributions of various baryonic resonances with masses below 2 GeV and using inputs from one pion production measured in the same experiment. A very good description of the two pion production is achieved allowing for an estimate of the contribution of one and double baryon-resonance excitation. Using appropriate kinematical cuts the ρ meson signal could also be extracted.

High spin resonances produced in π+π−π− and π−π0π0 systems at VES setup

A study of high spin resonances produced in π+π−π− and π−π0π0 systems with 29 GeV/c π− beam on Be target is presented. About 87 million events for the first one and 32 million events for the second one are collected with VES setup in a wide range of transfer momentum squared 0 < |t′| < 1 GeV2/c2. For both reactions this is the largest statistics in the world. The data are analysed using the PWA formalism of full rank density matrix and rank 1 density matrix. The a3(1875) and a4(2040) meson parameters are given and their production mechanism is discussed.

Resonator for microwave magnetoelectric effect

The design of a ring resonator made on a microstrip transmission line is presented. A study of ferromagnetic resonance using this design was made. Computer simulation of a microstrip ring resonator was carried out, and amplitude-frequency characteristics were obtained.

Myocardial fibrosis by late gadolinium enhancement cardiovascular magnetic resonance in myotonic muscular dystrophy type 1: highly prevalent but not associated with surface conduction abnormality

BackgroundConduction disease and arrhythmias represent a major cause of mortality in myotonic muscular dystrophy type 1 (MMD1). Permanent pacemaker (PPM) implantation is the cornerstone of therapy to reduce cardiovascular mortality in MMD1. Cardiovascular magnetic resonance (CMR) studies demonstrate a high prevalence of myocardial fibrosis in MMD1, however the association between CMR myocardial fibrosis with late gadolinium enhancement (CMR-LGE) and surface conduction abnormality is not well established in MMD1.We investigated whether myocardial fibrosis by CMR-LGE is associated with surface conduction abnormalities meeting criteria for PPM implantation according to current guidelines in a cohort of patients with genetically confirmed MMD1.MethodsPatients with genetically confirmed MMD1 were retrospectively evaluated. 12-lead electrocardiography (ECG) performed within 6 months of CMR was necessary for inclusion. The severity and extent of MMD1 was quantified using a validated Muscular Impairment Rating Scale (MIRS). Based on current guidelines for device-based therapy of cardiac rhythm abnormalities, we defined surface conduction abnormality as the presence of ECG alterations meeting criteria for PPM implant (class I or II indications): PR interval > 200 ms (type I atrioventricular (AV) block) and/or mono or bifascicular block (QRS > 120 ms), or evidence of advanced AV block. Balanced steady-state free precession sequences (bSSFP) were used for assessment of left ventricular (LV) volumes and ejection fraction. MOdified Look-Locker Inversion Recovery (MOLLI) acquisition schemes were used to acquire T1 maps. Patients’ charts were reviewed up to 12 months post-CMR for occurrence of PPM implantation.ResultsFifty-two patients (38% male, 41 ± 14 years) were included. Overall, 31 (60%) patients had a surface conduction abnormality and 22 (42%) demonstrated midwall myocardial fibrosis by CMR-LGE. After a median of 57 days from CMR exam, 15 patients (29%) underwent PPM implantation. Subjects with vs. without surface conduction abnormality had significantly longer disease length (15.5 vs. 7.8 years, p = 0.015) and higher disease severity on the MIRS scale (p = 0.041). High prevalence of myocardial fibrosis by CMR-LGE was detected in subjects with and without surface conduction abnormality with no significant difference between the two cohorts (42% vs. 43%, p = 0.999). By multivariate logistic regression analysis, disease length was the only independent variable associated with surface conduction abnormality (OR 1.071, 95%CI 1.003–1.144, p = 0.040); while CMR-LGE was not associated with conduction abnormality (ρ = − 0.009, p = 0.949).ConclusionsMyocardial fibrosis by CMR-LGE is highly prevalent in MMD1 but not related to surface conduction abnormality meeting current guideline criteria for PPM implantation .

Modulation of the aggregation of an amyloidogenic sequence by flanking-disordered region in the intrinsically disordered antigen merozoite surface protein 2.

The abundant Plasmodium falciparum merozoite surface protein MSP2, a potential malaria vaccine candidate, is an intrinsically disordered protein with some nascent secondary structure present in its conserved N-terminal region. This relatively ordered region has been implicated in both membrane interactions and amyloid-like aggregation of the protein, while the significance of the flanking-disordered region is unclear. In this study, we show that aggregation of the N-terminal conserved region of MSP2 is influenced in a length- and sequence-dependent fashion by the disordered central variable sequences. Intriguingly, MSP2 peptides containing the conserved region and the first five residues of the variable disordered regions aggregated more rapidly than a peptide corresponding to the conserved region alone. In contrast, MSP2 peptides extending 8 or 12 residues into the disordered region aggregated more slowly, consistent with the expected inhibitory effect of flanking-disordered sequences on the aggregation of amyloidogenic ordered sequences. Computational analyses indicated that the helical propensity of the ordered region of MSP2 was modulated by the adjacent disordered five residues in a sequence-dependent manner. Nuclear magnetic resonance and circular dichroism spectroscopic studies with synthetic peptides confirmed the computational predictions, emphasizing the correlation between aggregation propensity and conformation of the ordered region and the effects thereon of the adjacent disordered region. These results show that the effects of flanking-disordered sequences on a more ordered sequence may include enhancement of aggregation through modulation of the conformational properties of the more ordered sequence.

Abstract 17263: Pre-Clinical Left Ventricular Myocardial Remodeling in Patients With Friedreich’s Ataxia: A Cardiac MRI Study

Background: Heart Failure (HF) is the most common cause of death in Friedreich’s ataxia (FRDA), an inherited mitochondrial disease. Myocardial fibrosis is a well-documented histopathological feature among FRDA patients with HF. Objectives: In this study we will investigate the myocardial extracellular volume fraction (ECV) and intracellular water lifetime (τ ic ), using T1-weighted CMR imaging, in a cohort of patients with FRDA without signs of heart failure. We will also investigate whether myocardial tissue phenotyping by CMR can highlight particular characteristics of LV remodeling in FRDA’s cardiomyopathy, beyond those currently assessed with imaging-based classification of disease severity. Methods: Twenty-six FRDA’s patients (age 26.6±9.3 years, 15 women) without signs of HF, and 10 healthy controls (32.6±7.3 years, 5 women) underwent cardiac magnetic resonance (CMR) studies for assessment of left ventricular (LV) function, myocardial T1, late gadolinium enhancement (LGE), extracellular volume fraction (ECV), and intracellular water-lifetime (τ ic ) as marker of cardiomyocyte size. Neurological decline was determined using the FRDA rating scale (FARS 3). Results: FRDA patients had normal LV ejection fraction (LVEF: 67.66±11.4 vs. 63.9±9.0, P=0.311), larger LV mass index (LVMASSi: 61.03±22.1 vs. 45±4.2g/m 2 , P<0.001), and decreased LV end-diastolic volume index (LVEDVi 53.42±12 vs. 75.7±16.1, P=0.002), compared with controls. ECV and τ ic , were increased in FRDA patients (ECV: 0.36±0.05 vs. 0.25±0.02, P<0.0001; τ ic : 0.13±0.07 vs. 0.06±0.03, P=0.001). ECV was positively associated with LV mass-to-volume ratio (r=0.628, P<0.001). FARS 3 correlated positively with disease duration (r=0.669, P<0.001), and negatively with τ ic , (r=0.478, P=0.039). LVMASSi and cardiomyocyte mass-index [(1–ECV)LVMASSi] declined with age, indicating that LV hypertrophy may transition to a “burn-out” phase with LV atrophy. Conclusions: LV hypertrophy in FRDA reflects an expansion of the myocardial interstitium and an increase in cardiomyocyte size. In contrast, the neurological decline was more likely with decreasing cardiomyocyte size, possibly an early sign of myocardial “burn-out” in FRDA.

Ferromagnetic resonance of quasiperiodic Au/Co Fibonacci multilayers: Magnetic anisotropy and interlayer coupling

Abstract Ferromagnetic resonance (FMR) study of quasiperiodic Au/Co Fibonacci multilayers revealed that uniform resonance modes related to the bulk Co and interface Au/Co regions of Co layers were excited in all multilayers. Paramagnetic and spin-wave resonance (SWR) modes also were observed into multilayers associated to higher order Fibonacci sequence. The FMR results show that there is no direct correlation between the number of absorption modes and the number of magnetic layers or the Fibonacci generation sequence of the quasiperiodic structure. Analysis of SWR modes revealed an interlayer effective coupling constant higher than that known for conventional Au/Co multilayers.