Effect of inclining strain on the crystal lattice along an extended series of lanthanide hydroxysulfates Ln(OH)SO4 (Ln = Pr-Yb, except Pm)

A series of trivalent lanthanide hydroxysulfates, Ln(OH)SO(4), (Ln = Pr through Yb, except radioactive Pm) has been synthesized via hydrothermal methods from Ln(2)(SO(4))(3)·8H(2)O by reaction with aqueous NaOH at 170 °C in Teflon lined Parr steel autoclaves, and were characterized by single crystal X-ray diffraction and FT-IR spectroscopy. Two types of arrangements were found in the solid state. The lighter (Ln = Pr-Nd, Sm-Gd) and heavier lanthanide(III) hydroxysulfates (Tb-Yb) are each isostructural. Both structure types exhibit the monoclinic space group P2(1)/n, but the unit cell content is doubled with two crystallographically distinct LnO(8) polyhedra for the heavier lanthanide compounds. The lighter complexes maintain the coordination number 9, forming a three-dimensional extended lattice. The heavier counterparts exhibit the coordination number 8, and arrange as infinite columns of two crystallographically different LnO(8) polyhedra, while extending along the "c" axis. These columns of LnO(8) polyhedra are surrounded and separated by six columns of sulfate ions, also elongating in the "c" direction. The rigid sulfate entities seem to obstruct the closing in of the lighter LnO(9) polyhedra, and show an inclining degree of torsion into the "ac" layers. The crystal lattice of the lighter 4f complexes can sufficiently withstand the tension buildup, caused by the decreasing Ln(3+) radius, up to Gd(OH)SO(4). The energy profile of this structural arrangement then seems to exceed levels at which this structure type is favorable. The lattice arrangement of the heavier Ln-analogues seems to offer a lower energy profile. This appears to be the preferred arrangement for the heavier lanthanide hydroxysulfates, whose crystal lattice exhibits more flexibility, as the coordination sphere of these analogues is less crowded. The IR absorbance frequencies of the hydroxide ligands correlate as a function of the Ln(3+) ionic radius. This corresponds well with the X-ray single crystal analysis data.     

Sensitivity Analysis of Contact Type Vibration Measuring Sensors

With the Internet of Things (IoT) era dawning in, we are surrounded by a plethora of sensors. The present paper focuses on MEMS-based vibration measuring accelerometers, which are ubiquitously present in smartphones, tablets, smartwatches/bands, etc. These contact type vibration sensors have the unique advantage of being very small, low cost, low power, less weighing, and easily accommodatable in electronics. However, the accuracy of these sensors needs to be quantified with respect to more accurate sensors. With this objective, the paper presents a comparison of the relative sensitivity of a MEMS-based accelerometer (MPU 6050), a Geophone, and a sensor from Xiaomi Y2 smartphone with respect to a more standard Piezoelectric ICP based accelerometer, when all sensors are tested on a shaker table. Data are measured with harmonic excitation over a frequency range of 2–184 Hz. The relative sensitivity of MPU 6050 was 90% accurate in the frequency range 18–116 Hz for RMS measurements. Other sensors such as the one used in the Xiaomi Y2 smartphone and the Geophone were less accurate. The relative sensitivity measured in this work can be used to obtain sensitivity and hence more accurate data from these low-cost accelerometers.     

Astroparticle physics: Working group report

The astroparticle physics working group witnessed intense discussion and activity covering a broad range of topics ranging from supergravity and baryogenesis to compact stars and the large scale structure of the Universe. A summary of some of the subject areas in which collaborations were initiated during WHEPP-5 is presented below.     

Stereoselective synthesis of (S)-dapoxetine: a chiral auxiliary mediated approach

An imidazolidin-2-one chiral auxiliary mediated acetate aldol reaction was explored in the enantioselective synthesis of (S)-dapoxetine (SSRI). The diastereoselective aldol adduct was transformed to highly enantiopure (S)-dapoxetine with overall good yield.     

Electroactive Prussian Blue Encapsulated Iron Oxide Nanostructures for Mediator‐Free Cholesterol Estimation

Iron oxide nanoparticles of size ～10 nm have been encapsulated into four nanometer thick shells of Prussian blue and were then electrophoretically deposited onto an indium tin oxide substrate. The immobilization of cholesterol oxidase has been done onto the nanostructured film to investigate the kinetic parameters and biosensing characteristics. The fabricated bioelectrode exhibits an electron transfer coefficient and a charge transfer rate constant of 0.45 and 45.15 s^?1, respectively. Direct electron transfer properties of the nanostructured film result in 3^rd generation cholesterol biosensor. The bioelectrode exhibits high sensitivity (2.15 mAM^?1 cm^?2), a low K_m^app value (0.07 mM), good stability and high selectivity towards cholesterol.     

A facile approach to substituted acrylates by regioselective and stereoselective addition of thiols and amines to an alkynyl ester in water

Abstract  

Water-promoted hydrothiolation and hydroamination of ethyl propiolate leading to highly regioselective and stereoselective formation of thioacrylates and β-enamino esters in excellent yields, by a simple, efficient, and environmentally friendly reaction procedure without employing any hazardous reagent or solvent is reported.     

Nanocrystalline films of Au-Ag, Au-Cu, and Au-Ag-Cu alloys formed at the organic-aqueous interface

By the reaction of the appropriate organometallic precursors and tetrakishydroxymethyl phosphonium chloride (THPC) at the toluene-water interface, we have prepared nanocrystalline films of Au-Ag and Au-Cu alloys with a range of compositions. The films have been characterized by X-ray diffraction, electron microscopy, optical spectroscopy, and other techniques, besides compositional analysis. The particle size of the nanocrystals in the films varies with the composition. The surface plasmon band of the alloy films as well as of the organosols obtained by the disintegration of the films by the addition of an alkanethiol show the expected composition dependence. It has been possible to prepare the nanocrystalline films of a ternary Au-Ag-Cu alloy.     

Republication of: The cosmological constant and the theory of elementary particles (By Ya. B. Zeldovich)

The seminal paper by Ya. B. Zeldovich (Soviet Physics Uspekhi 11, 381–393, 1968) is reprinted here, together with an editorial comment on its lasting scientific relevance, and a biography of the author.

Development of gel polymer electrolyte based on LiTFSI and EMIMFSI for application in rechargeable lithium metal battery with GO-LFP and NCA cathodes

Journal of Solid State Electrochemistry - In this paper, we report the effect of ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIMFSI) on polymer poly(ethylene oxide) (PEO)...     

Quantum effects in the Bertotti-Robinson metric

Scalar and spin $\text{1}\text{2}$ fields have been studied in the Bertotti-Robinson space-time and analytical solutions have been obtained for the Klein-Gordon equation and the Dirac equation. For large e particle creation takes place as in the pseudoeuclidean metric under the influence of a constant external field.