EXAFS investigations on the pressure induced local structural changes of GeSe2glass under different hydrostatic conditions

Pressure-induced transformations in glassy GeSe2 have been studied using the x-ray absorption spectroscopy. Experiments have been carried out at the scanning-energy beamline BM23 (European Synchrotron Radiation Facility) providing a micrometric x-ray focal spot up to pressures of about 45 GPa in a diamond anvil cell. Both Se and Ge K-edge experiments were performed under different hydrostatic conditions identifying the metallization onsets by accurate determinations of the edge shifts. The semiconductor-metal transition was observed to be completed around 20 GPa when neon was used as a pressure transmitting medium (PTM), while this transition was slightly shifted to lower pressures when no PTM was used. Accurate double-edge extended x-ray absorption fine structure (EXAFS) refinements were carried out using advanced data-analysis methods. EXAFS data-analysis confirmed the trend shown by the edge shifts for this disordered material, showing that the transition from tetrahedral to octahedral coordination for Ge sites is not fully achieved at 45 GPa. Results of present high pressure EXAFS experiments have shown the absence of significant neon incorporation into the glass within the pressure range up to 45 GPa

Long-Term Outcomes with Subcutaneous C1-Inhibitor Replacement Therapy for Prevention of Hereditary Angioedema Attacks

Background For the prevention of attacks of hereditary angioedema (HAE), the efficacy and safety of subcutaneous human C1-esterase inhibitor (C1-INH[SC]; HAEGARDA, CSL Behring) was established in the 16-week Clinical Study for Optimal Management of Preventing Angioedema with Low-Volume Subcutaneous C1-Inhibitor Replacement Therapy (COMPACT). Objective To assess the long-term safety, occurrence of angioedema attacks, and use of rescue medication with C1-INH(SC). Methods Open-label, randomized, parallel-arm extension of COMPACT across 11 countries. Patients with frequent angioedema attacks, either study treatment-naive or who had completed COMPACT, were randomly assigned (1:1) to 40 IU/kg or 60 IU/kg C1-INH(SC) twice per week, with conditional uptitration to optimize prophylaxis (ClinicalTrials.gov registration no. NCT02316353). Results A total of 126 patients with a monthly attack rate of 4.3 in 3 months before entry in COMPACT were enrolled and treated for a mean of 1.5 years; 44 patients (34.9%) had more than 2 years of exposure. Mean steady-state C1-INH functional activity increased to 66.6% with 60 IU/kg. Incidence of adverse events was low and similar in both dose groups (11.3 and 8.5 events per patient-year for 40 IU/kg and 60 IU/kg, respectively). For 40 IU/kg and 60 IU/kg, median annualized attack rates were 1.3 and 1.0, respectively, and median rescue medication use was 0.2 and 0.0 times per year, respectively. Of 23 patients receiving 60 IU/kg for more than 2 years, 19 (83%) were attack-free during months 25 to 30 of treatment. Conclusions In patients with frequent HAE attacks, long-term replacement therapy with C1-INH(SC) is safe and exhibits a substantial and sustained prophylactic effect, with the vast majority of patients becoming free from debilitating disease symptoms

Las microesferas de Valle Morín, estado Aragua, Venezuela: Evidencia de impacto meteórico.

En Ia región de Camatagua, al sureste del pueblo de Valle Morín, en el curso de Ia quebrada Camatagúita se. reconocieron en muestras de lutita carbonática y limolita silícea, varias microesferas con brillo metálico. Estas microesferas fueron estudiadas con lupa binocular, microscopía electrónica de barrido y microanálisis químico cualitativo mediante espectroscopía por energía dispersa de rayos X, interpretándose como equivalentes metálicos de microtectitas. El origen por el impacto de un cuerpo extraterrestre de estas microesferas se infiere a partir de evidencias en su morfología superficial y composición química. Se trata del primer hallazgo documentado en Venezuela de estos corpúsculos. Su posición en el tiempo (Cretacico Tardío), así como Ia presencia de cuerpos simi!ares y estructuras asociadas en el Caribe, las hace candidatas para continuar estudios posteriores pertinentes, que permitan profundizar sobre su origen y ver sus relaciones con formas simi!ares del área. Abstract Various microspheres with metallic luster have been recognized in mudrocks from the Camatagua region, south-east of the Valle Morin town, along the course of the Camataguita creek. These microspheres were studied with the aid of a binocular magnifier, scanning electron microscope and semiquantitative energy dispersive X-ray spectroscopy, suggesting them to represent the metallic equivalents of microtektites. The impact related origin is suggested by surface morpho!ogy and chemical composition. This is the first documented find of cosmic microspheres in Venezuela, and because of the age of the rocks in which they where found (Late Cretaceous), as well as the presence of similar bodies and related structures in the Caribbean region, it makes them interesting for further studies that could provide new insight on their origin and relationship with similar bodies in the Caribbean

Direct and inverse problems for second-order integro-differential operator equations in an unbounded time interval

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Identification problems for pseudohyperbolic integrodifferential operator= equations

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

A novel electrochemical flow-cell for operando XAS investigations in X-ray opaque supports

Improvement of electrochemical technologies is one of the most popular topics in the field of renewable energy. However, this process requires a deep understanding of the electrode-electrolyte interface behavior under operando conditions. X-ray absorption spectroscopy (XAS) is widely employed to characterize electrode materials, providing element-selective oxidation state and local structure. Several existing cells allow studies as close as possible to realistic operating conditions, but most of them rely on the deposition of the electrodes on conductive and X-ray transparent materials, from where the radiation impinges the sample. In this work, we present a new electrochemical flow-cell for operando XAS that can be used with X-ray opaque substrates, since the signal is effectively detected from the electrode surface, as the radiation passes through a thin layer of electrolyte (∼17 μm). The electrolyte can flow over the electrode, reducing bubble formation and avoiding strong reactant concentration gradients. We show that high-quality data can be obtained under operando conditions, thanks to the high efficiency of the cell from the hard X-ray regime down to ∼4 keV. We report as a case study the operando XAS investigation at the Fe and Ni K-edges on Ni-doped γ-Fe2O3 films, epitaxially grown on Pt substrates. The effect of the Ni content on the catalytic performances for the oxygen evolution reaction is discussed. © 2024 The Royal Society of Chemistry

Low-field magnetic resonance imaging in the evaluation of mechanical and biological heart valve function.

Magnetic resonance imaging (MRI) has been frequently considered unsafe for patients with ferromagnetic implants: risks to be considered include induction of electric current, heating and dislocation of the prosthesis. Previous in vitro and in vivo studies have indicated the possibility of performing MRI examinations on patients with prosthetic heart valves. The aim of our study was to verify the presence of artifacts at the level of the prosthetic heart valve in vivo using a low-field MR unit (0.2 T) and to define the possibility of a functional analysis of the valve in patients with biomedical or mechanical prostheses. We evaluated 14 patients surgically treated for implantation of nine biological and seven mechanical aortic and mitral valves. A low-field MR unit (0.2 T) was employed using cine-MR technique on long- and short-axis view. The images were acquired on planes parallel and perpendicular to the valvular plane. Semiquantitative analysis with double-blind evaluation for definition of the extent of the artifact was performed. Three classes of artifacts were distinguished from minimal to significant. The examinations showed the presence of minimal artifacts in all biological heart valves and moderate artifacts in mechanical valves giving good qualitative data on blood flow near the valve. Analysis of the flow behind the valve showed signs of normal function in 13 prostheses and pathological findings in the remaining three. In these latter cases, MRI was able to define the presence of a pathologic aortic pressure gradient, mitral insufficiency and malpositioning of the mitral valve causing subvalvular turbulence. Nevertheless, we believe that the application of velocity-encoding cine-MR is more promising than semiquantitative analysis of artifacts

A Two-Dimensional Borophene Supercapacitor

This work introduces a new two-dimensional (2D) borophene-based (BB) supercapacitor produced by a chemical vapor deposition method and used in the facile fabrication of nanosupercapacitors (spin-coating on graphite substrates). Structural properties of the as-prepared borophene sheets are fully characterized via AFM, HRTEM, and FESEM, and Raman spectrum of the 2D sheets is scrutinized and discussed, as well as the electrochemical response of the fabricated nanosupercapacitors. A high specific capacity (sCap) of 350 F g(-1) is attributed to the device according to the electrochemical tests, that is almost three times higher than previous boron-based supercapacitors and surpasses the best reported 2D materials including graphene. Based on the surface charge-storage mechanism, it is posited that the electrical conductivity and surface area of 2D electrode materials highly affect the performance of the supercapacitor. Simulation studies are also conducted using joint density-functional theory (JDFT), the results of which are in agreement with the reported outcomes of experiments. Application of the newly synthesized 2D BB supercapacitors in the current study is expected to be promising in the energy storage field, inventive class of sensing devices, as well as novel highly sensitive biosensors

Aluminum-Activated Borophene Nanosheets with Enhanced Oxidation Resistance for Nanoelectronic Devices

Two-dimensional borophene nanosheets are sensitive to oxygen, which has hindered their development and use in scientific research and subsequent applications. Conventional methods of borophene synthesis are based on its epitaxial growth on single-crystal metal substrates by using molecular beam epitaxy (MBE). The electron deficiency of boron atoms in the borophene structure has made the use of metal substrates in the growth process inevitable. Hence, a method to stabilize the borophene sheets for further applications seems necessary. In this work, the oxidation arrangement of Al-activated chemical vapor deposition (CVD) of borophene sheets was investigated via scanning photoemission microscopy (SPEM). This method allows the investigation of oxidation ordering via its high spatial resolution and elemental sensitivity. The results indicate the persistence of the borophene χ3 (and some β12) phase after exposure to air. The formation of boron oxide is primarily limited to the Al aggregated islands and the edges while maintaining the borophene configuration intact. Our results show that the electronic exchange between the Al aggregates and the interface of boron atoms at the edges of the borophene sheet can prevent the oxidation process and preserve the borophene sheets for long periods. The lower oxidation tendency of the Al-saturated borophene was confirmed via density functional theory calculation, showing a lower oxygen binding energy on Al/borophene compared with that of the metal-free borophene. The oxidation-resistive borophene can be exploited in innovative high-efficiency catalytic, electronic, and sensing devices. © 2024 American Chemical Society