Material superconductor Bi-2212 procesado a diferentes presiones y caracterizados por DRX, MEB y mediciones eléctricas

Este trabajo tuvo como propósito preparar muestras en volumen de composición nominal Bi₁․₆Pb₀․₄ Sr₂CaCu₂Oδ, a presiones de compactación diferentes para observar el efecto sobre sus propiedades estructurales y eléctricas. El material cerámico superconductor se preparó por reacción química en estado sólido, con presiones de compactación de 300 a 900 MPa. Se obtuvo el comportamiento eléctrico temperatura-resistencia (T-R) de las muestras, por el método de las cuatro puntas. Se caracterizaron estructuralmente por DRX y morfológicamente por MEB. Los patrones de difracción de rayos X muestran las reflexiones de la fase Bi-2212 y Bi- 2223 para todas las muestras. Los valores más altos de y Tc onset y Tc offset se observan en aproximadamente 111.6 K y 101.2 K, respectivamente para la muestra a 600 MPa. Las imágenes MEB muestran la morfología de los granos presentes en las muestras, observando disminución y uniformidad en la porosidad a 600 MPa.The purpose of this work was to prepare samples in bulk with nominal composition Bi₁․₆Pb₀․₄ Sr₂CaCu₂Oδ, at different compaction pressures to observe the effect on electrical and structural properties. The superconducting ceramic material was prepared by reaction in solid state, with compaction pressures from 300 to 900 MPa. The temperature- electrical resistance (T-R) behavior of the samples was obtained by the four-probe method. They were structurally characterized by XRD and morphologically by SEM. The X-ray diffraction patterns show the reflections of the Bi-2212 and Bi-2223 phases for all the samples, which vary slightly in intensity in relation to the formation of the superconducting phases. The highest values of Tc onset and Tc offset are observed approximately 111.6 K and 101.2 K, respectively for the sample compacted at 600 MPa. The images obtained by MEB show the morphology of the grains present in the samples, observing decrease and uniformity in the porosity at 600 MPa

Direct Polyphenol Attachment on the Surfaces of Magnetite Nanoparticles, Using Vitis vinifera, Vaccinium corymbosum, or Punica granatum

This study presents an alternative approach to directly synthesizing magnetite nanoparticles (MNPs) in the presence of Vitis vinifera, Vaccinium corymbosum, and Punica granatum derived from natural sources (grapes, blueberries, and pomegranates, respectively). A modified co-precipitation method that combines phytochemical techniques was developed to produce semispherical MNPs that range in size from 7.7 to 8.8 nm and are coated with a ~1.5 nm thick layer of polyphenols. The observed structure, composition, and surface properties of the MNPs@polyphenols demonstrated the dual functionality of the phenolic groups as both reducing agents and capping molecules that are bonding with Fe ions on the surfaces of the MNPs via –OH groups. Magnetic force microscopy images revealed the uniaxial orientation of single magnetic domains (SMDs) associated with the inverse spinel structure of the magnetite (Fe3O4). The samples’ inductive heating (H0 = 28.9 kA/m, f = 764 kHz), measured via the specific loss power (SLP) of the samples, yielded values of up to 187.2 W/g and showed the influence of the average particle size. A cell viability assessment was conducted via the MTT and NRu tests to estimate the metabolic and lysosomal activities of the MNPs@polyphenols in K562 (chronic myelogenous leukemia, ATCC) cells

CO and C 3

ZnSb2O6 has been synthesized by a microwave-assisted solution method in order to test its possible application as a gas sensor. Zinc nitrate, antimony trichloride, and ethylenediamine were used as precursors and deionized water as solvent. Microwave radiation, with a power of ~350 W, was applied for solvent evaporation. The thermal decomposition of the precursors leads to the formation of ZnSb2O6 at 600°C. This oxide crystallized in a tetragonal structure with cell parameters a=4.66 Å, c=9.26 Å and space group P42/mnm. Microwires and microrods formed by nanocrystals were observed by means of scanning and transmission electron microscopies (SEM and TEM, resp.). Pellets of the oxide were tested as gas sensors in flowing atmospheres of carbon monoxide (CO) and propane (C3H8). Sensitivity increased with the gas concentration (0–300 ppm) and working temperatures (ambient, 150 and 250°C) increase. The results indicate high sensitivity of ZnSb2O6 in both gases at different concentrations and operating temperatures

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

За кадры. 1932. № 17

Качество учебы решается не только в учебной аудитории, но и в столовой и общежитииПоступкам официантки Воробьевой П. и ей подобных не должно быть места в столовойСтоловая должна быть, достойной "кафедрой" общественного питания СММИВ перевыборы КСМ организации мобилизуем все силы комсомола на борьбу за качество учебы, за первенство СММИ / Кощеева"Мелочи", которые мешают заниматься, снижают качество учебы / Г. Б.Советская, 11 узкое место среди общежитий механиков / В. П.Лицо выпускной 24-25 группыВыпускники вперед к новым победам на фронте индустриализации нашей страны / С. В. ГолашевскийЛучшие ударники выпускной 24 - 25 группы, выделенные на премирование / И.Не к лицу ударному ВТУЗУ / И.Энергетики в бой за качество учебы, за возврат Красного Знамя. ЭнергоотделениеМарксистско - Ленинское воспитаниеФильченбаум не оправдал доверие студенческих масс / И

Nanobiomechanical behavior of Fe3O4@SiO2 and Fe3O4@SiO2-NH2 nanoparticles over HeLa cells interfaces

International audienceIn this work, we studied the impact of magnetic nanoparticles (MNPs) interactions with HeLa cells when they are exposed to high frequency alternating magnetic field (AMF). Specifically, we measured the nanobiomechanical properties of cell interfaces by using Atomic Force Microscopy (AFM). The Magnetite (Fe3O4) MNPs were synthesized by coprecipitation and encapsulated with silica (SiO2): Fe3O4@SiO2 and functionalized with amino groups (-NH2): Fe3O4@SiO2-NH2, by sonochemical processing. HeLa cells were incubated or not with MNPs, then exposed or not to AMF at 37 °C. A biomechanical analysis was then performed through AFM, providing the Young's modulus and stiffness of the cells. The statistical analysis (p < 0.001) showed that AMF application or MNPs interaction modify the biomechanical behavior of the cell interfaces. Interestingly, the most significant difference was found for HeLa cells incubated with Fe3O4@SiO2-NH2 and exposed to AMF, showing that local heat of these MNPs modify elasticity and stiffness

Development of a Parenteral Formulation of NTS-Polyplex Nanoparticles for Clinical Purpose

Neurotensin (NTS)-polyplex is a nanoparticle system for targeted gene delivery that holds great promise for treatment of Parkinson’s disease and various types of cancer. However, the high instability in aqueous suspension of NTS-polyplex nanoparticles is a major limitation for their widespread clinical use. To overcome this obstacle, we developed a clinical formulation and a lyophilization process for NTS-polyplex nanoparticles. The reconstituted samples were compared with fresh preparations by using transmission electron microscopy, dynamic light scattering, electrophoretic mobility, circular dichroism and transfection assays in vitro and in vivo. Our formulation was able to confer lyoprotection and stability to these nanoparticles. In addition, transmission electron microscopy (TEM) and size exclusion-high performance liquid chromatography (SEC-HPLC) using a radioactive tag revealed that the interaction of reconstituted nanoparticles with fetal bovine or human serum did not alter their biophysical features. Furthermore, the formulation and the lyophilization procedure guaranteed functional NTS-polyplex nanoparticles for at least six months of storage at 25 °C and 60% relative humidity. Our results offer a pharmaceutical guide for formulation and long-term storage of NTS-polyplex nanoparticles that could be applied to other polyplexes