LACTATE ANALYSIS IN HUMAN HUMOUR VITREOUS AS BIOMARKER IN THE ESTIMATION OF POST-MORTEM INTERVAL

Forensic Sciences frequently require the time since death, or Post Mortem Interval (PMI) evaluation. This parameter can be investigated by studying the biochemical changes occurring in the corpse after death. Humour Vitreous (HV) is preferred as matrix since it allows a protected environment from mi-crobial action and is easy to collect. Post mortem HV lactate level has been evaluated mainly in relation to glucose metabolism disease concerning the cause of death, nevertheless some investigation observed HV lactate increase with PMI. Thus, the aim of this work was to evaluate the existence of a correlation between the vitreous lactate concentration and PMI. The novelty of present research is also the selected analytical technique, capillary zone electrophoresis (CZE), that has been investigated to carry out these measurements. The HV as biological matrices for forensic investigation confirms suitability and lactate analysis with reproducibility, specificity and sensitivity was successfully assessed. HV samples of known PMI were analysed and lactate concentrations matched the values reported in literature and demonstrated increase with PMI with a linear trend. Despite this work is only a preliminary method validation and would need further optimization, CZE demonstrated to be an optimal technique for this analysis, anyhow the presence of factors influencing the results emerged and earliest personal and literature measurements demonstrated that these aspects represent future investigation topics

(INVITED) Energy transfer processes in Sr3Tb(PO4)3 eulytite-type materials singly doped with Nd3+ and Sm3+

In this study the optical spectroscopy, the excited state dynamics and in particular the energy transfer Tb3+→Ln3+ (Ln = Nd or Sm), have been investigated in detail in eulytite double phosphate hosts of the type Sr3Tb(PO4)3 doped with 1 mol% Ln3+. It has been found that for Ln=Nd and Sm, the energy transfer efficiency (ηT) is 0.76 and 0.73, respectively, thanks to the assistance of fast migration in the Tb3+ 5D4 level. The pathway responsible for the transfer of excitation has been unambiguously identified in the case of Sr3Tb0.99Nd0.01(PO4)3, whilst the situation is more complex for Sr3Tb0.99Sm0.01(PO4)3, due to high density of the final Sm3+ states that could be involved. The Tb3+→Nd3+ energy transfer has been tentatively attributed to the exchange interaction on the basis of the short transfer distance and multipolar selection rules

Theoretical and Experimental Investigation of the Tb3+-Eu3+ Energy Transfer Mechanisms in Cubic A3Tb0.90Eu0.10({PO}4)3 (A = Sr, Ba) Materials

In this study the optical spectroscopy, the excited state dynamics, and in particular the Tb3+ -> Eu3+ energy transfer, have been investigated in detail both from the theoretical and experimental point of view in eulytite double phosphate hosts A(3)Tb(PO4)(3) (A = Sr, Ba) doped with Eu3+. It has been found that the energy transfer is strongly assisted by fast migration in the donor Tb3+ subset. Moreover, the transfer rates and efficiencies depend significantly on the nature of the divalent elements present in the structure and hence on the distances between Tb3+-Eu3+ nearest neighbors. It is shown that the competition between quadrupole-quadrupole and exchange interaction is crucial in accounting for the transfer rates

Spectroscopic and Structural Properties of β-Tricalcium Phosphates Ca9RE(PO4)7 (RE = Nd, Gd, Dy)

Rare-earth-based Ca9RE(PO4)7 (RE = Nd, Gd, Dy) materials were synthesized by solid-state reaction at T = 1200 °C. The obtained tricalcium phosphate (TCP) materials are efficient light emitters due to the presence of RE3+ ions, although these ions are present at high concentrations. Moreover, in these host structures, these ions can be used as optical probes to study their local environments. Thus, photoluminescence (PL) emission spectra of the powder samples clearly indicated, for Dy3+ and Gd3+ ions, the presence of the RE3+ ion in low-symmetry sites with some local structural disorder, and the spectra show the presence of vibrational features (in the case of Gd3+). For the Nd3+ phase, emission bands are present around 900, 1050, and 1330 nm, originating from the 4F3/2 level. In general, these RE-TCP samples are interesting luminescent materials in the visible (Dy), UV (Gd), and NIR (Nd) regions, due to weak concentration quenching even for high concentrations of the emitting ion

Tb3+\u2192Eu3+ energy transfer processes in eulytite A3Tb(PO4)3 (A=Sr, Ba) and silico-carnotite Ca3Tb2Z3O12 (Z=Si, Ge) materials doped with Eu3+

In this study the optical spectroscopy, the excited state dynamics and in particular the Tb3+-> Eu3+ energy transfer, have been investigated in detail in eulytite double phosphate and silico-carnotite silicate or germanate hosts based on the Tb3+ ion and doped with Eu3+. It has been found that the energy transfer rates and efficiencies depend significantly on the nature of the divalent elements present in the two different structural families, opening the way to the control of the energy transfer rate and efficiency, on the basis of chemical and structural properties

Sensitivity of a solid Eu(III) complex towards acetonitrile vapor: Structural and spectroscopic characterization

The Eu(III) nitrate complex of the meso- N,N'-bis(2-pyridylmethylene)-1,2-(R,S)-cyclohexanediamine ligand was synthesized and characterized by single crystal and powder X-ray diffraction. The crystal lattice of the complex is capable of absorbing and desorbing selectively acetonitrile molecules, at 293 K upon an acetonitrile vapor pressure of similar to 0.1 x 10(5) Pa. This process, which is partially reversible, can be easily followed by both powder X-ray diffraction (P-XRD) and Eu(III) luminescence spectroscopy. The acetonitrile molecule, located in the outer coordination sphere of the metal ion, does not affect the radiative transition probability of D-5(0) level of Eu(III) and also it does not activate further non-radiative channels from this level. On the other hand, this molecule is capable of affecting the energy position and intensities of the crystal field components of the D-5(0) -> F-7(2) transition. The complex in solid form can be considered a promising material for the optical sensing of acetonitrile vapors

Optical Study of Diamine Coupling on Carboxyl-Functionalized Mesoporous Silicon

A functionalization strategy, consisting of a silylation reaction by acrylic acid followed by diamine coupling, preserves and stabilizes the photoluminescence (PL) of porous silicon (pSi) microparticles suspended in ethanol. We found that under the condition of efficient amine coupling, besides the orange emission typical of the native pSi, an emission band in the blue region appears. The investigation of the interaction between pSi and diamine shows that diamine quenches and shifts the orange band meanwhile it induces an increase of the intensity of the blue one. PL lifetimes of the orange and blue bands are in the micro and nano second range, respectively. These values and their wavelength dependence clearly prove that the two bands have different origin: quantum confinement and nitrogen impurities introduced at silicon/silicon oxide interface, respectively. Thus, they can be used to discriminate between the pSi microparticles obtained by silylation, which expose carboxylic groups and the pSi microparticles after the diamine coupling, which bear amine functionalities at the surface. The increase in the stability of the PL emission of pSi in aqueous solution after functionalization, with quantum yields of the order of 1\u20132%, supports the use in biological systems of these brightly emitting, largely porous microparticles, bearing positive or negative surface charg

Characterization and Luminescence of Eu3+- and Gd3+-Doped Hydroxyapatite Ca10(PO4)6(OH)2

Luminescence properties of europium-doped Ca10-xEux(PO4)6(OH)2 (xEu = 0, 0.01, 0.02, 0.10 and 0.20) and gadolinium-doped hydroxyapatite Ca9.80Gd0.20(PO4)6(OH)2 (HA), synthesized via solid-state reaction at T = 1300 °C, were investigated using scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR), and luminescence spectroscopy. Crystal structure characterization (from unit cell parameters determination to refined atomic positions) was achieved in the P63/m space group. FTIR analyses show only slight band shifts of (PO4) modes as a function of the rare earth concentration. Structural refinement, achieved via the Rietveld method, and luminescence spectroscopy highlighted the presence of dopant at the Ca2 site. Strong luminescence was observed for all Eu- and Gd-doped samples. Our multi-methodological study confirms that rare-earth (RE)-doped synthetic hydroxyapatites are promising materials for bio-imaging applications

Shape Preserving Single Crystal to Amorphous to Single Crystal Polymorphic Transformation Is Possible

Many crystalline materials form polymorphs and undergo solid-solid transitions between different forms as a function of temperature or pressure. However, there is still a poor understanding of the mechanism of transformation. Conclusions about the transformation process are typically drawn by comparing the crystal structures before and after the conversion, but gaining detailed mechanistic knowledge is strongly impeded by the generally fast rate of these transitions. When the crystal morphology does not change, it is assumed that crystallinity is maintained throughout the process. Here we report transformation between polymorphs of ZnCl2(1,3-diethylimidazole-2-thione)(2) which are sufficiently slow to allow unambiguous assignment of single crystal to single crystal transformation with shape preservation proceeding through an amorphous intermediate phase. This result fundamentally challenges the commonly accepted views of polymorphic phase transition mechanisms.Funding Agencies|Novo Nordisk FoundationNovo Nordisk FoundationNovocure Limited; Knut and Alice Wallenberg FoundationKnut &amp; Alice Wallenberg Foundation; Royal Academy of Sciences, Sweden; Swedish Research Council (Vetenskapsradet, VR)Swedish Research Council [2018-05973, 2020-05405, 2018-00233, 2020-04600, SNIC 2020-3-29]</p

New Ca2.90(Me2+)0.10(PO4)2 -tricalcium Phosphates with Me2+ = Mn, Ni, Cu: Synthesis, Crystal-Chemistry, and Luminescence Properties

Ca2.90Me2+0.10(PO4)2 (with Me = Mn, Ni, Cu) β-tricalcium phosphate (TCP) powders were synthesized by solid-state reaction at T = 1200 °C and investigated by means of a combination of scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, and luminescence spectroscopy. SEM morphological analysis showed the run products to consist of sub spherical microcrystalline aggregates, while EDS semi-quantitative analysis confirmed the nominal Ca/Me composition. The unit cell and the space group were determined by X-ray powder diffraction data showing that all the compounds crystallize in the rhombohedral R3c whitlockite-type structure, with the following unit cell constants: a = b = 10.41014(19) Å, c = 37.2984(13) Å, and cell volume V = 3500.53(15) Å3 (Mn); a = b = 10.39447(10) Å, c = 37.2901(8) Å; V = 3489.22(9) Å3 (Ni); a = b = 10.40764(8) Å, c = 37.3158(6) Å, V = 3500.48(7) Å3 (Cu). The investigation was completed with the structural refinement by the Rietveld method. The FTIR spectra are similar to those of the end-member Ca β-tricalcium phosphate (TCP), in agreement with the structure determination, and show minor band shifts of the (PO4) modes with the increasing size of the replacing Me2+ cation. Luminescence spectra and decay curves revealed significant luminescence properties for Mn and Cu phases