843 research outputs found
The digital code driven autonomous synthesis of ibuprofen automated in a 3D-printer-based robot
An automated synthesis robot was constructed by modifying an open source 3D printing platform. The resulting automated system was used to 3D print reaction vessels (reactionware) of differing internal volumes using polypropylene feedstock via a fused deposition modeling 3D printing approach and subsequently make use of these fabricated vessels to synthesize the nonsteroidal anti-inflammatory drug ibuprofen via a consecutive one-pot three-step approach. The synthesis of ibuprofen could be achieved on different scales simply by adjusting the parameters in the robot control software. The software for controlling the synthesis robot was written in the python programming language and hard-coded for the synthesis of ibuprofen by the method described, opening possibilities for the sharing of validated synthetic ‘programs’ which can run on similar low cost, user-constructed robotic platforms towards an ‘open-source’ regime in the area of chemical synthesis
Anisotropic valence-->core x-ray fluorescence from a [Rh(en)3][Mn(N)(CN)5]·H2O single crystal: Experimental results and density functional calculations
High resolution x-ray fluorescence spectra have been recorded for emission in different directions from a single crystal of the compound [Rh(en)3][Mn(N)(CN)5]·H2O. The spectra are interpreted by comparison with density functional theory (DFT) electronic structure calculations. The Kbeta[double-prime] line, which is strongly polarized along the Mn–N axis, can be viewed as an N(2s)-->Mn(1s) transition, and the angular dependence is understood within the dipole approximation. The so-called Kbeta2,5 region has numerous contributions but is dominated by Mn(4p) and C(2s)-->Mn(1s) transitions. Transition energy splittings are found in agreement with those of calculated occupied molecular orbitals to within 1 eV. Computed relative transition probabilities reproduce experimentally observed trends
Resonant X-ray emission spectroscopy reveals d–d ligand-field states involved in the self-assembly of a square-planar platinum complex
Resonant X-ray Emission Spectroscopy (RXES) is used to characterize the ligand field states of the prototypic self-assembled square-planar complex, [Pt(tpy)Cl]Cl (tpy=2,2′:6′,2′′-terpyridine), and determine the effect of weak metal-metal and π-π interactions on their energy. © 2012 the Owner Societies
A portable 3D printer system for the diagnosis and treatment of multidrug-resistant bacteria
Summary: Multidrug-resistant bacteria are a major threat to human health, but broad-spectrum
antibiotics are losing efficacy. There is a need to screen a given drug against
a bacterial infection outside of the laboratory. To address this need, we have designed
and built an inexpensive and easy-to-use 3D-printer-based system that
allows easily readable quantitative tests for the performance of antibacterial
drugs. The platform creates a sterile diagnostic device by using 3D printing,
and the device is filled automatically with growth medium, and then antibiotics
are sprayed onto the medium by ink-jet technology. The sample for testing can
be introduced via a fluid port, and the printer hot bed is used to incubate the device,
allowing operation in the field. Combining advantages from various established
tests of antibacterial performance, this allows the comparison of a specific
antibiotics and bacteria. Also, this system can create and test several antibiotic
formulations for therapeutic use, and we demonstrate this potential by investigating
a mixture of pathogens that are only killed by a mixture of drugs
High-resolution Mn K-edge x-ray emission and absorption spectroscopy study of the electronic and local structure of the three different phases in Nd0.5Sr0.5MnO3
Nd0.5Sr0.5MnO3 is particularly representative of mixed-valent manganites since their three characteristic macroscopic phases (charge-ordered insulator, ferromagnetic-metallic, and paramagnetic insulator) appear at different temperatures.We here report a complete x-ray emission and absorption spectroscopy (XES-XAS) study of Nd0.5Sr0.5MnO3 as a function of temperature to investigate the electronic and local structure changes of the Mn atom in these three phases. Compared with the differences in the XES-XAS spectra between Nd0.5Sr0.5MnO3 and the single-valent reference compounds NdMnO3 (Mn3+) and Sr/CaMnO3 (Mn4+), only modest changes have been obtained across the magnetoelectrical transitions. The XES spectra, including both the Mn Kα and Kβ emission lines, have mainly shown a subtle decrease in the local spin density accompanying the passage to the ferromagnetic-metallic phase. For the same phase, the small intensity variations in the pre-edge region of the high-resolution XAS spectra reflect an increase of the p-d mixing. The analysis of these XAS spectra imply a charge segregation between the two different Mn sites far from one electron, being in intermediate valences Mn+3.5±δ/2(δ < 0.2 e−) for all the phases. Our results indicate that the spin, charge, and geometrical structure of the Mn atom hardly change among the three macroscopic phases demonstrating the strong competition between the ferromagnetic conductor and the charge-0rdered insulator behaviors in the manganites
Hard x-ray photon-in-photon-out spectroscopy with lifetime resolution – of XAS, XES, RIXSS and HERFD
Spectroscopic techniques that aim to resolve the electronic configuration and local coordination of a central
atom by detecting inner-shell radiative decays following photoexcitation using hard X-rays are presented. The
experimental setup requires an X-ray spectrometer based on perfect crystal Bragg optics. The possibilities arising from
non-resonant (X-Ray Emission Spectroscopy - XES) and resonant excitation (Resonant Inelastic X-Ray Scattering
Spectroscopy – RIXSS, High-Energy-Resolution Fluorescence Detected (HERFD) XAS) are discussed when the
instrumental energy broadenings of the primary (beamline) monochromator and the crystal spectrometer for x-ray
emission detection are on the order of the core hole lifetimes of the intermediate and final electronic states. The small
energy bandwidth in the emission detection yields line-sharpened absorption features. In transition metal compounds,
electron-electron interactions as well as orbital splittings and fractional population can be revealed. Combination with
EXAFS spectroscopy enables to extent the k-range beyond unwanted absorption edges in the sample that limit the
EXAFS range in conventional absorption spectroscopy
The magnetic exciton of EuS revealed by resonant inelastic x-ray scattering
We report the valence-to-core resonant inelastic x-ray scattering (RIXS) of
EuS measured at the L3 edge of Eu. The obtained data reveal two sets of
excitations: one set is composed of a hole in the S 3p bands and an electron
excited to extended Eu 5d band states, the other is made up from a hole in the
Eu 4f states and an electron in localized Eu 5d states bound to the 4f hole by
its Coulomb potential. The delocalized excitations arise from the
dipole-allowed 5d to 2p emissions, whereas the localized excitations result
from the dipole-forbidden (quadrupole-allowed) 4f to 2p emissions. Both these
emission channels have a comparable intensity thanks to a small number of
occupied 5d states (approximately 0.6) combined with a large number of occupied
4f states (seven). We identify the localized electron-hole pairs with the
"magnetic excitons" suggested in the past as an interpretation of the sharp
features seen in the optical absorption spectra. Our observations provide a
direct experimental evidence of these excitons which has been missing up to
now.Comment: 7 pages, 4 figures, supplemental material (PDF, 8 pages) added as an
ancillary fil
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