The origin and significance of euhedral apatite crystals on conodonts

Crystal overgrowth on fossil remains is well-documented in the literature. Attention has specifically focused on bioapatite (i.e., an apatite of biochemical origin regardless of post-mortem changes) configurations, in order to decipher any possible relation to fossilization/diagenesis. This study investigates the Rare Earth Element (REE) and other High-Field-Strength Element (HFSE) composition of euhedral crystals formed on the surface of conodont elements compared with that of crystal-free surfaces. Euhedral crystals are by definition crystals characterized by sharp faces, developing solids that, for apatite, assume the form of hexagonal prisms, reflecting its crystal symmetry. Late Ordovician (Amorphognathus ordovicicus Zone) conodonts from two localities in Sardinia and the Carnic Alps (Italy) are herein investigated. Conodont elements reveal the occurrence of smooth surfaces and surfaces partially covered with euhedral crystals. Since euhedral crystals did not reasonably grow during the organism’s lifetime, the REE and HFSE analysis can provide important insights into the crystal growth process. The experimental results indicated a substantial contribution of diagenetic imprinting for all the analyzed material, although more evident on euhedral crystals that are significantly enriched in middle and, subordinately, in heavy REE with respect to smooth surfaces. The positive correlations between La + Th vs log[ΣREE] and Ce + Th vs log[ΣREE] could support the hypothesis that the neoformed euhedral crystals grew also by depleting the pristine bioapatite of the conodont elements. Nevertheless, the occurrence of two types of apatite cannot be ruled out: euhedral crystals as neoformed products of diagenetic processes and smooth surfaces as remains of the pristine conodont bioapatite after diagenesis

Optimizing Hempcrete Properties Through Thermal Treatment of Hemp Hurds for Enhanced Sustainability in Green Building

This study examines the effects of the thermal pre-treatment of hemp hurds on the physical, mechanical, and thermal properties of hempcrete, evaluating its potential as a sustainable building material. Hemp hurds were pre-treated at various temperatures (120–280 °C) and characterized by proximate analysis, CHNS elemental analysis, and thermogravimetric analysis (TGA). The resulting hempcrete samples were analyzed for density, water absorption, compressive strength, and thermal conductivity. Three different hempcrete formulations, with varying lime:hemp proportions, were analyzed. The findings indicate that higher pre-treatment temperatures lead to reduced density and water absorption across all formulations. Formulations containing a higher hemp hurd content had lower densities but higher water absorption values. Compressive strength increased consistently with the pre-treatment temperature, suggesting that higher temperatures enhance matrix bonding and structural rigidity, and with the lime content. However, thermal conductivity also rose with pre-treatment, with only the composition containing the highest hemp hurd content maintaining the optimal insulation threshold (0.1 W/mK). This suggests a trade-off between compressive strength and insulation performance, influenced by the balance of hemp hurd and lime content. These findings underscore the potential of thermal pre-treatment to tailor hempcrete properties, promoting its application as a durable, moisture-resistant material for sustainable building, though the optimization of hurd–lime ratios remains essential

Search for the Supersymmetric Partner of the Top-Quark in ppˉp \bar{p} Collisions at s=1.8TeV\sqrt{s} = 1.8 {\rm TeV}

We report on a search for the supersymmetric partner of the top quark (stop) produced in $t \bar{t}$ events using $110 {\rm pb}^{-1}$ of $p \bar{p}$ collisions at $\sqrt{s} = 1.8 {\rm TeV}$ recorded with the Collider Detector at Fermilab. In the case of a light stop squark, the decay of the top quark into stop plus the lightest supersymmetric particle (LSP) could have a significant branching ratio. The observed events are consistent with Standard Model $t \bar{t}$ production and decay. Hence, we set limits on the branching ratio of the top quark decaying into stop plus LSP, excluding branching ratios above 45% for a LSP mass up to 40 {\rm GeV/c}$^{2}$.Comment: 11 pages, 4 figure

Measurement of the B0 anti-B0 oscillation frequency using l- D*+ pairs and lepton flavor tags

The oscillation frequency Delta-md of B0 anti-B0 mixing is measured using the partially reconstructed semileptonic decay anti-B0 -> l- nubar D*+ X. The data sample was collected with the CDF detector at the Fermilab Tevatron collider during 1992 - 1995 by triggering on the existence of two lepton candidates in an event, and corresponds to about 110 pb-1 of pbar p collisions at sqrt(s) = 1.8 TeV. We estimate the proper decay time of the anti-B0 meson from the measured decay length and reconstructed momentum of the l- D*+ system. The charge of the lepton in the final state identifies the flavor of the anti-B0 meson at its decay. The second lepton in the event is used to infer the flavor of the anti-B0 meson at production. We measure the oscillation frequency to be Delta-md = 0.516 +/- 0.099 +0.029 -0.035 ps-1, where the first uncertainty is statistical and the second is systematic.Comment: 30 pages, 7 figures. Submitted to Physical Review

To be or not to be a conodont. The controversial story of Pseudooneotodus and Eurytholia

The genus Pseudooneotodus (Drygant, 1974) is a genus of small and conical elements widely distributed from the Middle Ordovician to the Early Devonian throughout the world. Because of its unusual shape, Pseudooneotodus has long been considered enigmatic, and only in the late nineties of the last century the genus has been finally placed within conodonts according to histological data. This study investigates possible similarities between Pseudooneotodus and Eurytholia (Sutton et al., 2001), an incertae sedis genus of enigmatic plates with a phosphate composition. An association of over one hundred specimens of Pseudooneotodus beckmanni and Eurytholia bohemica was analyzed from conodont residues in two distinct geographical areas: the Prague Basin (Požáry and Mušlovka sections, Bohemia, Czech Republic) and the Carnic Alps (Rauchkofel Boden section, Austria). Through an investigation that combines the use of optical and electron microscopy (including focused ion beam scanning electron microscopy), X-ray microdiffraction, and trace element (HFSE) analysis by mass spectrometry, differences between these fossil groups were observed and compared with data resulting from typical conodonts (Dapsilodus obliquicostatus, Panderodus unicostatus and Wurmiella excavata) recovered from the same samples

How Much Can We Trust Major Element Quantification in Bioapatite Investigation?

Bioapatite is probably the key factor in the unreplicated success of vertebrates. Chemical data on bioapatite composition can be achieved on a solid sample by using different analytical tools such as spectroscopic and spectrometric methods. As analytical outputs can be affected by the physical-chemical characteristics of the sample matrix, an internal standard is usually required to correct and validate the results. Bioapatite lattice can accommodate iso- and heterovalent substitutions during life or diagenesis varying its chemical composition through (geological) time. If on the one hand, this makes bioapatite a unique archive of physical and chemical information for both the living cycle and the events occurring after death, on the other, it excludes the identification of a sole internal standard. Here, we propose a method to measure major element concentration with specific care for P, Ca, Mg, Na, K, Si, Al, and Fe, which are the main substituent atoms in bioapatite, through homemade matrix-matched external calibration standards for laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). We tested the method on living and fossil shark teeth, critically comparing the results obtained using other analytical techniques and certified external standards. We demonstrated that matrix-matched calibration in LA-ICPMS is mandatory for obtaining a reliable chemical characterization even if factors such as matrix aggregation variability, diverse presence of volatile compounds, the fossilization footprint, and the instrumental variability can represent further variability parameters

Technological Prospects of Biochar Derived from Viticulture Waste: Characterization and Application Perspectives

The increasing demand for sustainable agricultural practices aimed at reducing carbon dioxide emissions has driven the exploration of converting viticulture residues into biochar. This study investigates the potential technological applications of biochar as a filler for the production of electrically conductive composite materials, suitable to Bipolar Plate (BP) manufacturing. Grape seeds (GSs), defatted grape seeds (DGSs), wood stems (WSs), and whole grape seeds (WGSs) were converted into biochar samples through low-temperature (300 °C) pyrolysis for 3 or 24 h. The composition and thermal stability of biochar were evaluated through thermogravimetric analysis (TG), which provided valuable insights into interpreting the in-plane conductivity (IPC) values of the BP samples. Pyrolyzed GS and DGS biochar samples demonstrated enhanced thermal stability and conferred higher IPC values compared to WS counterparts. This indicates a clear correlation between the formation of carbon-rich structures during pyrolysis and overall electrical conductivity. In contrast, pyrolyzed WGSs produced BP samples with lower IPC values due to the presence of lipids, which were not effectively degraded by the low-temperature pyrolysis

Search for ZZ and ZW Production in ppbar Collisions at sqrt(s) = 1.96 TeV

We present a search for ZZ and ZW vector boson pair production in ppbar collisions at sqrt(s) = 1.96 TeV using the leptonic decay channels ZZ --> ll nu nu, ZZ --> l l l' l' and ZW --> l l l' nu. In a data sample corresponding to an integrated luminosity of 194 pb-1 collected with the Collider Detector at Fermilab, 3 candidate events are found with an expected background of 1.0 +/- 0.2 events. We set a 95% confidence level upper limit of 15.2 pb on the cross section for ZZ plus ZW production, compared to the standard model prediction of 5.0 +/- 0.4 pb.Comment: 7 pages, 2 figures. This version is accepted for publication by Phys. Rev. D Rapid Communication

Measurement of the kinematic variables of beauty particles produced in 350 GeV/c π−\pi^--Cu interactions

Using a sample of $26$ b\=b events, produced in $350\,\hbox{GeV}/c$ $\pi^-$ interactions in a copper target, which includes $13$ events where the decays of both $B$ and $\overline{B}$ are well reconstructed, we measure the differential distributions with respect to $x_F$ and $p_T^2$ as well as some two-particle kinematic variables. We also compare our results with a previous experiment and with predictions based on perturbative QCD

3D Bioprinting for Musculoskeletal Applications

This review focuses on developments in the field of bioprinting for musculoskeletal tissue engineering, along with discussion on the various approaches for bone, cartilage and connective tissue fabrication. All approaches (cell-laden, cell-free and a combination of both) aim to obtain a complex, living tissues able to develop and mature, using the same fundamental technology. To date, co-printing of cell-laden and cell-free materials has been revealed to be the most promising approach for musculoskeletal applications because materials with good bioactivity and good mechanical strength can be combined within the same constructs. Bioprinting for musculoskeletal applications is a developing field, and detailed discussion on the current challenges and future perspectives is also presented in this review