Morphology and Anatomy of Leaf, Stem and Petiole of Luvunga crassifolia Tanaka (Rutaceae)

Luvunga crassifolia is an underutilized plant in the Citrus family. Other than brief morphological descriptions, there are no published reports on other identification features of this plant. Thus, the current study was aimed to investigate macroscopic and microscopic diagnostic features of L. crassifolia leaves, stems, and petioles. Macroscopic characterization, optimization of histological procedure, and histochemical analyses of differential stains were carried out on the leaves, stems, and petioles of L. crassifolia. The histological method was optimized by modifying the following parameters: number of fixation days, dehydration duration with degraded series of ethanol or butanol, clearing duration, and infiltration duration. After infiltration, embedding and sectioning of the tissues were performed. Histochemical analyses were carried out using differential stains to identify the cellular components in leaf, stem and, petiole tissue sections. This study showed that L. crassifolia leaves are amphistomatic. Pellucid dots were observed on both adaxial and abaxial leaf surfaces. Secretory cavities, xylem, phloem, and pericyclic fibers were found in the cross-sections of leaf, stem, and petiole. Calcium oxalates were present in the leaf and stem sections, while trichomes were detected in stem and petiole sections. The information obtained from this study will be helpful for the identification and future taxonomic-related studies of this plant species.

Thermal Stability of Calcium Oxalates from CO2 Sequestration for Storage Purposes: An In-Situ HT-XRPD and TGA Combined Study

Calcium oxalates are naturally occurring biominerals and can be found as a byproduct of some industrial processes. Recently, a new and green method for carbon capture and sequestration in stable calcium oxalate from oxalic acid produced by carbon dioxide reduction was proposed. The reaction resulted in high-quality weddellite crystals. Assessing the stability of these weddellite crystals is crucial to forecast their reuse as solid-state reservoir of pure CO2 and CaO in a circular economy perspective or, eventually, their disposal. The thermal decomposition of weddellite obtained from the new method of carbon capture and storage was studied by coupling in-situ high-temperature X-ray powder diffraction and thermogravimetric analysis, in order to evaluate the dehydration, decarbonation, and the possible production of unwanted volatile species during heating. At low temperature (119–255 °C), structural water release was superimposed to an early CO2 feeble evolution, resulting in a water-carbon dioxide mixture that should be separated for reuse. Furthermore, the storage temperature limit must be considered bearing in mind this CO2 release low-temperature event. In the range 390–550 °C, a two-component mixture of carbon monoxide and dioxide is evolved, requiring oxidation of the former or gas separation to reuse pure gases. Finally, the last decarbonation reaction produced pure CO2 starting from 550 °C.

Biofilm Medium Chemistry and Calcium Oxalate Morphogenesis

The present study is focused on the effect of biofilm medium chemistry on oxalate crystallization and contributes to the study of the patterns of microbial biomineralization and the development of nature-like technologies, using the metabolism of microscopic fungi. Calcium oxalates (weddellite and whewellite in different ratios) were synthesized by chemical precipitation in a weakly acidic environment (pH = 4–6), as is typical for the stationary phase of micromycetes growth, with a ratio of Ca2+/C2O42− = 4.0–5.5, at room temperature. Additives, which are common for biofilms on the surface of stone in an urban environment (citric, malic, succinic and fumaric acids; and K+, Mg2+, Fe3+, Sr2+, SO42+, PO43+ and CO32+ ions), were added to the solutions. The resulting precipitates were studied via X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). It was revealed that organic acids, excreted by micromicetes, and some environmental ions, as well as their combinations, significantly affect the weddellite/whewellite ratio and the morphology of their phases (including the appearance of tetragonal prism faces of weddellite). The strongest unique effect leading to intensive crystallization of weddellite was only caused by the presence of citric acid additive in the medium. Minor changes in the composition of the additive components can lead to significant changes in the weddellite/whewellite ratio. The effect of the combination of additives on this ratio does not obey the law of additivity. The content of weddellite in the systems containing a representative set of both organic acids and environmental ions is ~20 wt%, which is in good agreement with natural systems.

Ca, Cu and Pb solubilization and biomineralization by microorganisms: case study from Kamchatka, Russia

<p>The role of microorganisms (lichens, micromycetes and bacteria) in the formation of biominerals is widely known (Purvis, 2008; Vlasov et al., 2020). In the fall of 2019, we organized an expedition to the area of Tolbachik volcano (cones 1, 2, 3 and Mount 1004), Kamchatka, Russia, and collected 120 samples of volcanic rocks with biofilms. The volcanic cones of Tolbachik concentrate a wide variety of elements and are a type-locality of more than 300 minerals (Vergasova and Filatov, 2012; Siidra et al., 2017; Pekov et al., 2018). Lichen species are widespread in the volcanic fields of Kamchatka, Russia (Kukwa et al., 2014).  The goal of this work was to search for and study biominerals associated with lichens.</p><p>As a result of our research, calcium oxalates (whewellite and weddellite) and copper oxalates (moolooite) associated with lichens were found. Whewellite was found in the lichens <em>Psylolechia leprosa</em> and<em> Sarcogyne hypophaea</em>. Whewellite and weddellite were found together in the lichen <em>Rinodina gennarii</em>. Pyroxene (diopside) and plagioclase (anorthite) sourced calcium for the oxalates formation. Whewellite accumulates in apothecia in the form of whitish masses, consisting of lamellar crystals of 5-6 microns in size and their stacked intergrowths. Weddellite forms bipyramidal crystals of 2-10 microns in size. Moolooite was found in lichens <em>Acarospora squamulosa</em> and <em>Lecanora polytropa</em> (together with whewellite). The source of copper is tenorite, atacamite and copper-rich silicates (products of basalt processing by fumaroles). Moolooite forms lamellar crystals and intergrowths up to 5-6 microns in size. An interesting feature of oxalate formations in the <em>Lecanora polytropa</em> lichen is a high lead content, which has never been previously recorded in natural oxalates. Linarite and pyromorphite are most likely the source of lead. Chemical analysis showed that "nests" of calcium oxalates can contain up to 6 wt% PbO, while "nests" of copper oxalate - no more than 1 wt% PbO. The results obtained indicate the possibility selective sorption of lead and suggest the possibility of replacing calcium with lead in the oxalates. The studies of the location forms of lead in biofilms are in progress. The exact form of lead has not yet been established. Linarite and pyromorphite are most likely the source of lead. <em>This research was supported by Russian Science Foundation grant (19-17-00141) and performed at the resource centers of St. Petersburg State University (MM, XRD, Geomodel).</em></p><p>Fedotov S.A. (ed.). Great fissure Tolbachik eruption (1975-1976, Kamchatka) // Moscow: Nauka. 1984. 637 p.</p><p>Kukwa M. et al. // The Lichenologist. 2014. 46. 1. P. 129–131.</p><p>Pekov I.V. et al. // Acta Cryst. 2018. B74. P. 502–518.</p><p>Purvis O.W. et al. // Mineralogical Magazine. 2008. 72. 2. P. 607–616.</p><p>Siidra O.I. et al. // European Journal of Mineralogy. 2017. 29. 3. P. 499–510.</p><p>Vergasova L.P. and Filatov S.K. // Volcanology and Seismology. 2012. 5. P. 3–12.</p><p>Vlasov D.Yu. et al. In: Aspergillus niger: pathogenicity, cultivation and uses, Nova Science Publishers, New York. 2020. P. 2-121.</p>

About the Role of Fluorine-Bearing Apatite in the Formation of Oxalate Kidney Stones

Using electron microprobe analysis, 17 kidney stones containing apatite were studied. According to the results of the research, it was found that the apatite of all the oxalate kidney stones contained fluorine, while in the apatite of the phosphate kidney stones, fluorine was present in trace amounts or absent. Direct correlation between the amount of oxalate mineral phases and the fluorine content was observed. Ionic substitutions in the apatite of kidney stones have a multidirectional effect on the unit cell parameters. The fluorine content increases with the increase of a unit cell parameter, which is probably associated with a simultaneous increase in the amount of H2O in the structure of apatite. The results of thermodynamic modeling show that fluorapatite is stable at lower pH values than hydroxylapatite, and therefore can be a precursor of calcium oxalates crystallization.

Characterization of Biominerals in Cacteae Species by FTIR

A biomineral is a crystalline or amorphous mineral product of the biochemical activity of an organism and the local accumulation of elements available in the environment. The cactus family has been characterized by accumulating calcium oxalates, although other biominerals have been detected. Five species of Cacteae were studied to find biominerals. For this, anatomical sections and Fourier transform infrared, field emission scanning electron microscopy and energy dispersive x-ray spectrometry analyses were used. In the studied regions of the five species, they presented prismatic or spherulite dihydrate calcium oxalate crystals, as the predominant biomineral. Anatomical sections of Astrophytum asterias showed prismatic crystals and Echinocactus texensis amorphous silica bodies in the hypodermis. New findings were for Ariocarpus retusus subsp. trigonus peaks assigned to calcium carbonate and for Mammillaria sphaerica peaks belonging to silicates.

Ending the Cinderella Status of Terraces and Lynchets in Europe

<p>Terraces and lynchets are not only ubiquitous worldwide and within Europe but can provide increasingly important Ecosystem Services (ESs), which may be able to mitigate aspects of climate change. They are also probably a major cause of non-linearity between climate and erosion rates in agricultural systems as noted from alluvial and colluvial studies. In this paper we review the theoretical background of terraces and lynchets, present a modified classification, and show how new techniques are transforming the study of these widespread and often ancient anthropogenic landforms. Indeed the problems of dating terraces and also the time-consuming nature and costly surveys has held back the archaeological study of terraces until now. The applicable suite of techniques available now includes the creation of Digital Terrain Models (DTMs) from Structure from Motion (SfM) photogrammetry, Airborne and Terrestrial Laser Scanning (ALS-TLS); the use of OSL and pOSL, pXRF, FTIR, phytoliths, calcium oxalates from plants and potentially sedaDNA. Examples will be drawn from a recently started ERC project (TerrACE; ERC-2017-ADG: 787790, 2018-2023; https://www.terrace.no/) which is working at over 10 sites in Europe ranging from Norway to Greece.</p><p>This paper explains the development of a new holistic approach to terrace archaeology driven by a modern conceptualisation of human-landscape relationships, and facilitated by new scientific developments. We explain the rationale for our choice of case study areas, for example, the range of bio-climatic zones. In addition, this multi-regional approach allows us to address contingent regional and local historical/socioeconomic processes; from demographic fluctuations to the development of specific forms of agricultural techniques. Examples of DTM creation, field analyses and selected results will be given from Martleburg in Belgium and sites in Italy. We will then move on to explain how this combination of a comprehensive suite of modern field and laboratory methods and an interpretive strategy informed by the environmental humanities will yield exciting and groundbreaking results.</p>

Synthesis and Characterization of (Ca,Sr)[C2O4]∙nH2O Solid Solutions: Variations of Phase Composition, Crystal Morphologies and in Ionic Substitutions

To study strontium (Sr) incorporation into calcium oxalates (weddellite and whewellite), calcium-strontium oxalate solid solutions (Ca,Sr)[C2O4]∙nH2O (n = 1, 2) are synthesized and studied by a complex of methods: powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Two series of solid solutions, isomorphous (Ca,Sr)[C2O4]·(2.5 − x)H2O) (space group I4/m) and isodimorphous Ca[C2O4]·H2O(sp.gr. P21/c)–Sr[C2O4]·H2O(sp.gr. P 1 - ), are experimentally detected. The morphogenetic regularities of their crystallization are revealed. The factors controlling this process are discussed.