Larger Cell Volume Research Articles

Predator-induced defense decreases growth rate and photoprotective capacity in a nitrogen-limited dinoflagellate, Alexandrium minutum

Some dinoflagellates produce toxic secondary metabolites that correlate with increased resistance to grazers. The allocation costs of toxin production have been repeatedly addressed, but with conflicting results. Few studies have considered the potential costs of this defense to the photosystem, even though defense toxins (e.g., karlotoxins and brevetoxins) are closely linked to the photoprotective process. Here, we used chemical cues from copepods to induce paralytic shellfish toxin (PST) production in resource-limited Alexandrium minutum and quantitatively determined the growth rate and potential trade-offs with the photosystem process. The results show that grazer-induced, more toxic A. minutum had larger cell volume, lower cell division rate, and lower pigment content under nitrogen-limited conditions than control cells. In addition, predator cues led to a lower relative abundance of photoprotective xanthophylls and a reduced de-epoxidation efficiency of the xanthophyll cycle under high light conditions, reducing the ability of the cells to resist photodamage. Decreased photoprotective capacity may reflect an overlooked defense cost of toxin production.

Mn-deficient ZnMn2O4/Zn0.5Mn0.5Fe2O4 cathode for enhancing structural reversibility and stability of zinc-ion batteries

Aqueous zinc-ion batteries have surfaced as a viable energy storage technology due to their safety, eco-friendliness, and cost-effectiveness. Binary zinc manganite oxide (ZnMn2O4 or ZMO) stands out as the potential cathode material owing to its considerable theoretical capacity and high operating voltage. However, high electrostatic repulsion of Zn2+ ions within ZMO leads to sluggish diffusion and poor reversibility of Zn2+ ions insertion/extraction that can reduce charge storage and overall cycling performance. This study addresses this challenge by introducing FeCl3 during the synthesis to form ZMO/Zn0.5Mn0.5Fe2O4 (ZMFO) cathode material. This cathode features Mn-deficient structures, which can reduce the electrostatic repulsion via low Mn occupancies and lattice parameters enlargement, thus facilitating Zn2+ ions diffusion. Ex-situ X-ray diffraction analyses further show that the cathode is able to maintain good structural reversibility during the charge-discharge cycles. Additionally, the ZMO/ZMFO cathode exhibits smaller particle sizes than pristine ZMO, providing a wider surface area. The presence of ZMFO with a large unit cell volume can also enhance Zn storage capacity and accelerate Zn2+ ions kinetics. Highlighting those advantages, aqueous zinc-ion batteries with ZMO/ZMFO cathode show a capacity of ~230 mAh g−1 at 0.05 A g−1 and retain 99 % of its initial capacity at 0.2 A g−1 after 200 cycles of charge-discharge.

ABa6Cu31Te22 (A = K, Rb, Cs) Featuring Polyanionic Copper-Telluride Frameworks with Ultralow Thermal Conductivity.

Three polyanionic tellurides, ABa6Cu31Te22 (A = K, Rb, Cs), were synthesized in salt flux. The isostructural tellurides crystallize in a new structure type, in the cubic Pa3 space group with a Wyckoff sequence of d10c2b1 and large unit cell volumes of over 5500 Å3. The structures feature a framework of [CuTe4] tetrahedra and [CuTe3] trigonal pyramids with disorder in the Cu sites. The polyanionic frameworks have large square antiprism and cuboctahedral voids where Ba and alkali metal cations are situated, forming [BaTe8] and [ATe12], respectively. The overall compositions are close to being charge balanced. The large [ATe12] cuboctahedra allowed for significant anisotropic displacement of the A cations, as observed from both single crystal X-ray diffraction and heat capacity studies. Alkali cations rattling together with Cu atom displacement and disorder leads to the dispersion of phonons, thus softening the lattice and subsequently reducing the thermal conductivity. Evaluations of the electronic band structure revealed the occurrence of a narrow bandgap together with the presence of a flat band near the valence band maximum, giving rise to the high thermopower. The Cs and Rb analogues show a slope change in the temperature dependence of electrical resistivity around room temperature, which is typical for semimetals or degenerate semiconductors. For the as-synthesized and unoptimized materials, high values of the thermoelectric figure-of-merit of ∼0.2 were observed at 623 K.

A New Family of High Oxidation State Antiperovskite Nitrides: La3MN5 (M = Cr, Mn and Mo).

Three new nitrides La3MN5 (M = Cr, Mn, and Mo) have been synthesized using a high pressure azide route. These are the first examples of ternary Cs3CoCl5-type nitrides, and show that this (MN4)NLa3 antiperovskite structure type may be used to stabilise high oxidation-state transition metals in tetrahedral molecular [MN4]n- nitridometallate anions. Magnetic measurements confirm that Cr and Mo are in the M6+ state, but the M = Mn phase has an anomalously small paramagnetic moment and large cell volume. Neutron powder diffraction data are fitted using an anion-excess La3MnN5.30 model (space group I4/mcm, a = 6.81587(9) Å and c = 11.22664(18) Å at 200 K) in which Mn is close to the +7 state. Excess-anion incorporation into Cs3CoCl5-type materials has not been previously reported, and this or other substitution mechanisms may enable many other high oxidation state transition metal nitrides to be prepared.

A New Family of High Oxidation State Antiperovskite Nitrides: La3MN5 (M=Cr, Mn and Mo)

AbstractThree new nitrides La3MN5 (M=Cr, Mn, and Mo) have been synthesized using a high pressure azide route. These are the first examples of ternary Cs3CoCl5‐type nitrides, and show that this (MN4)NLa3 antiperovskite structure type may be used to stabilise high oxidation‐state transition metals in tetrahedral molecular [MN4]n− nitridometallate anions. Magnetic measurements confirm that Cr and Mo are in the M6+ state, but the M=Mn phase has an anomalously small paramagnetic moment and large cell volume. Neutron powder diffraction data are fitted using an anion‐excess La3MnN5.30 model (space group I4/mcm, a=6.81587(9) Å and c=11.22664(18) Å at 200 K) in which Mn is close to the +7 state. Excess‐anion incorporation into Cs3CoCl5‐type materials has not been previously reported, and this or other substitution mechanisms may enable many other high oxidation state transition metal nitrides to be prepared.

Rheophytic Osmunda lancea (Osmundaceae) exhibits large flexibility in the petiole

The riparian zone, found alongside rivers and streams, is a unique habitat characterized by its vulnerability to sudden floods following intense rainfall. To cope with these challenging conditions, a specific group of plants with linear and lanceolate lamina have adapted to thrive in these environments. Despite their unique ability to withstand the forceful water flow, the specific adaptive characteristics of the petioles, which support the lamina remain unknown. Our morphological, anatomical, and mechanical analyses on the petioles of Osmunda lancea (Osmundaceae) along the river and an inland sister species of O. japonica revealed that the petioles of O. lancea had a larger cell volume in subepidermal cortex and were more flexible than those of O. japonica.

Aflatoxin assessment in food commodities: quantification using ICH-validated UPLC-FLD with large flow cell volume

Aflatoxin assessment in food commodities: quantification using ICH-validated UPLC-FLD with large flow cell volume

Clumped isotope reordering kinetics in strontianite and witherite: Experiments and first-principles simulations

The carbonate clumped isotope (∆47) thermometer is a powerful tool for temperature reconstruction based on the thermodynamical 13C—18O bonding preference. Accurate interpretation of temperatures requires preservation of original carbonate ∆47 signatures, which are susceptible to resetting at elevated temperatures during burial. Kinetic models of carbonate 13C—18O bond reordering derived from experimental studies constrain the evaluation of ∆47 preservation and the reconstruction of thermal histories and initial temperatures for reordered carbonates. However, application of these models to different carbonates is limited because kinetic parameters vary with materials and are believed to be affected by factors such as crystal structure, cation, trace element composition, crystal defects, and internal water whose roles in reordering are still not well-understood. Here we present reordering data for strontianite and witherite from heating experiments and evaluate the effects of crystal structure, cation chemistry, cation vacancy and substitution, and internal water on reordering using constrained ab-initio molecular dynamics (cAIMD) simulations. We show that strontianite and witherite reorder significantly faster than other carbonates. Comparing experimental studies yields the following reordering rate sequence: strontianite > witherite > aragonite > calcite > dolomite. The general trend in Arrhenius activation energy for reordering is strontianite < witherite < aragonite < dolomite < calcite (with calcite values based on the average of individual materials). Our cAIMD simulations reveal a similar trend in free energy of activation for oxygen exchange in these carbonates. We suggest that orthorhombic carbonates are more susceptible to reordering than trigonal carbonates because of the shorter distance between carbonate groups and because the weaker M—O interaction in orthorhombic carbonates reduces the structural distortion and the energy cost during transition state formation. For carbonates sharing the same structure, the weak M—O bonding can be compensated by a large unit cell volume, leading to a non-systematic relationship between the free energy of activation and the cation radius. In simulations with lattice-bound water, the free energy of activation is greatly reduced compared with cation vacancy and substitution. The influence of fluid inclusions on measured reordering rates depends on the fraction of carbonates that can exchange with water as suggested by strontianite δ¹⁸O data. Our results serve as a starting point for a more sophisticated but flexible kinetic model containing material-specific factors (e.g., substituted ions, structure water, etc.) for reordering in abiotic and biotic carbonates.

The Influence of Vibration and Moisture Content on the Compactness of the Substrate in Nursery Container Cells Determined with a Multipenetrometer

An important problem of container nurseries is ensuring equal and favorable growth conditions for cultivated plants. This can be achieved by ensuring the physical parameters of the substrate used to grow seedlings in individual cells of the container are similar. The nursery container is filled with a specially composed substrate through an automated line. Quickly controlling the parameters related to the quality of substrate filling presents a significant problem, as it requires the ongoing correction of the filling module settings (e.g., extending the vibration time or changing the vibration amplitude). To address this issue, it would be helpful to determine the compactness of the substrate, which can be easily measured using a penetrometer. This paper presents a prototype automated station, known as a multipenetrometer, designed for the simultaneous testing of compactness in 15 selected container cells. The prototype was put to the test at the Nursery Farm in Sukowo, where two types of polystyrene containers (V150—650/312/150 mm; 74 cells; and 0,148 cm3 cell volume and V300—650/312/180 mm; 53 cells; and 0.275 cm3 cell volume) were filled with peat–perlite substrate on the Urbinati Ypsilon automated line. This study investigated the influence of substrate moisture (two levels—70 and 75%) and vibration intensity (two levels—8 and 12 G) of the vibrating table on its compactness within the individual cells of the nursery container. The results indicated that with an increase in substrate moisture and vibration intensity, the compactness of the substrate increased, and the variation in compactness between individual cells decreased. Notably, the V300 containers, with a larger cell volume (265 cm3), experienced a higher level of change compared to the V150 containers (145 cm3). Despite the use of substrate compaction techniques based on the experience of line operators filling containers, the coefficient of variation between the compactness of the substrate in individual cells of the container remained at 30%. Based on the findings, it was confirmed that the optimal parameters for filling V150 and V300 containers with peat–perlite substrate on the Urbinati line, at a filling capacity of approximately 400 containers h−1, are a moisture content of around 75% and a maximum vibration intensity of 12 G.

Theoretical investigation of the barocaloric effect in spin-crossover systems upon first- and second-order phase transition conversion

We report a theoretical simulation of the barocaloric effect in spin crossover systems starting from a model Hamiltonian, which includes the crystalline electrical field, elastic, and phonon interactions. A systematic study, through the model parameters, allowed the construction of phase diagrams, and the contributions of configurational, magnetic, and phonon entropies for the barocaloric effect were investigated. The majority contribution comes from the phonons (about 76%, in our simulation), which were associated with the large cell volume change during the low-spin-(SL) ↔ high-spin-(HS) phase transition. Besides, the refrigerant capacity due to the barocaloric effect was discussed in the first- and second-order (LS) ↔ (HS) phase transition regimes. We find out that when hysteresis increases, with an increase in pressure, a higher barocaloric effect can be obtained.

3D Bioprinted Hydrogel Microfluidic Devices for Parallel Drug Screening.

Conventional high-throughput screening (HTS) platforms suffer from the need for large cell volumes, high reagent consumption, significant assembly cost, and handling efforts. The assembly of three-dimensional (3D) bioprinted hydrogel-based microfluidic chips within platforms can address these problems. We present a continuous and seamless manufacturing approach to create a bioprinted microfluidic chips with a circular pattern scalable toward HTS platforms. Digital light processing 3D bioprinting is used to tune the local permeability of our chip, made of polyethylene glycol diacrylate and cell-laden gelatin methacryloyl, for creating predefined gradients of biochemical properties. We measured the flow-induced physical characteristics, the mass transport of drug agents, and the biological features of the proposed chip. We measured reactive oxygen species from the encapsulated cells through an integrated process and showed the capacity of the hydrogel-based chip for creating drug/agent gradients. This work introduces a chip design based on a hydrogel that can be changed and could be used for modern HTS platforms such as in vitro organoids.

A versatile enhanced freeze-substitution protocol for volume electron microscopy.

Volume electron microscopy, a powerful approach to generate large three-dimensional cell and tissue volumes at electron microscopy resolutions, is rapidly becoming a routine tool for understanding fundamental and applied biological questions. One of the enabling factors for its adoption has been the development of conventional fixation protocols with improved heavy metal staining. However, freeze-substitution with organic solvent-based fixation and staining has not realized the same level of benefit. Here, we report a straightforward approach including osmium tetroxide, acetone and up to 3% water substitution fluid (compatible with traditional or fast freeze-substitution protocols), warm-up and transition from organic solvent to aqueous 2% osmium tetroxide. Once fully hydrated, samples were processed in aqueous based potassium ferrocyanide, thiocarbohydrazide, osmium tetroxide, uranyl acetate and lead acetate before resin infiltration and polymerization. We observed a consistent and substantial increase in heavy metal staining across diverse and difficult-to-fix test organisms and tissue types, including plant tissues (Hordeum vulgare), nematode (Caenorhabditis elegans) and yeast (Saccharomyces cerevisiae). Our approach opens new possibilities to combine the benefits of cryo-preservation with enhanced contrast for volume electron microscopy in diverse organisms.

Flagellar energy costs across the tree of life.

Flagellar-driven motility grants unicellular organisms the ability to gather more food and avoid predators, but the energetic costs of construction and operation of flagella are considerable. Paths of flagellar evolution depend on the deviations between fitness gains and energy costs. Using structural data available for all three major flagellar types (bacterial, archaeal, and eukaryotic), flagellar construction costs were determined for Escherichia coli, Pyrococcus furiosus, and Chlamydomonas reinhardtii. Estimates of cell volumes, flagella numbers, and flagellum lengths from the literature yield flagellar costs for another ~200 species. The benefits of flagellar investment were analysed in terms of swimming speed, nutrient collection, and growth rate; showing, among other things, that the cost-effectiveness of bacterial and eukaryotic flagella follows a common trend. However, a comparison of whole-cell costs and flagellum costs across the Tree of Life reveals that only cells with larger cell volumes than the typical bacterium could evolve the more expensive eukaryotic flagellum. These findings provide insight into the unsolved evolutionary question of why the three domains of life each carry their own type of flagellum.

A Borosilicide with Clathrate VIII Structure.

The high-pressure phase Na8BxSi46–x (3 < x < 5) is the first representative of a borosilicide crystallizing in the rarely occurring clathrate VIII type structure. Crystals with composition Na8B4Si42 (space group I43̅m; a = 9.7187(2) Å; Pearson symbol cI54) were obtained at 5–8 GPa and 1200 K. The clathrate I modification exists for the same composition at lower pressure with a larger cell volume (Pm3̅n; a = 9. 977(2) Å; cP54). Profound structural adaptions allow for a higher density of the clathrate VIII type than clathrate I, opening up the perspective of obtaining clathrate VIII type compounds as high-pressure forms of clathrate I.

Structural Complexity and Tuned Thermoelectric Properties of a Polymorph of the Zintl Phase Ca2CdSb2 with a Non-centrosymmetric Monoclinic Structure.

The Zintl phase Ca2CdSb2 was found to be dimorphic. Besides the orthorhombic Ca2CdSb2 (-o), here we report on the synthesis, the structural characterization, and the thermoelectric transport properties of its monoclinic form, Ca2CdSb2 (-m), and its Lu-doped variant Ca2-xLuxCdSb2 (x ≈ 0.02). The monoclinic structure exhibits complex structural characteristics and constitutes a new structure type with the non-centrosymmetric space group Cm (Z = 30). The electrical resistivity ρ(T) measured on single crystals of both phases portrays a transition from a semiconductor to a degenerate p-type semiconductor upon doping with Lu and with an attendant change in the Hall carrier concentration nH from 7.15 × 1018 to 2.30 × 1019 cm-3 at 300 K. The Seebeck coefficient S(T) of both phases are comparable and indicate a hole-dominated carrier transport mechanism with magnitudes of 133 and 116 μV/K at 600 K for Ca2CdSb2 (-m) and Ca2-xLuxCdSb2, respectively. The convoluted atomic bonding with an attendant large unit cell volume of ∼4365 Å3 drives a putative low thermal conductivity in these materials resulting in a power factor PF of 1.63 μW/cm K2 and an estimated thermoelectric figure of merit zT of ∼0.5 for Ca2-xLuxCdSb2 at 600 K. Differential scanning calorimetry results reveal the stability of these phases up to about 960 K, making them candidates for moderate temperature thermoelectric materials.

The highly disordered Zintl phase Ca10GdCdSb9 – New example of a p-type semiconductor with remarkable thermoelectric properties

Ca10GdCdSb9 is a new Zintl phase with a large unit cell volume (∼2500 Å3) and a very complex, disordered structure, which can drive the realization of ultralow thermal conductivity in this material. The measured Seebeck coefficient, α, for single-crystalline Ca10GdCdSb9 approaches 350 μV/K at 600 K. The experimentally determined electrical resistivity of Ca10GdCdSb9 is very low, leading to a remarkably high-power factor PF of 23.2 μW/cm·K2 at 460 K. The extraordinary PF value in this material, higher than those of the currently known state-of-the-art materials within the same temperature range, suggests that the Ca10RECdSb9 material system (RE = rare earth metal) could serve as a viable playground to harnessing new efficient thermoelectric generators.

Coupling between elastic strains and phase transition in dense pure zirconia polycrystals

A deep understanding of the solid-state phase transition processes of zirconia is a mandatory requirement for the development of new zirconia-based materials useful for many industrial applications. For five decades, the monoclinic $\ensuremath{\Leftrightarrow}$ tetragonal phase transition is described as a martensitic one and it is well known that it is associated with a large unit cell volume variation that promotes the appearance of elastic strains and also microcracking. In the present paper, we study, through in situ high temperature x-ray diffraction experiments, the coupling between strain relaxation and the martensitic phase transition into a pure zirconia bulk polycrystal. Quantitative analysis of the diffraction signal allows us to disentangle, with respect to the temperature variation, the phase transition and the microcracking processes, and we demonstrate that a high temperature postelaboration thermal treatment induces an increase in the stored elastic energy. Finally, we show that in such polycrystals exhibiting a crystal size distribution and in which the crystals are under internal stresses, the tetragonal to monoclinic phase transition process evolves from a first order one to a second order one when the temperature decreases.

Replacement of Cobalt in Lithium-Rich Layered Oxides by n-Doping: A DFT Study

The replacement of cobalt in the lattice of lithium-rich layered oxides (LRLO) is mandatory to improve their environmental benignity and reduce costs. In this study, we analyze the impact of the cobalt removal from the trigonal LRLO lattice on the structural, thermodynamic, and electronic properties of this material through density functional theory calculations. To mimic disorder in the transition metal layers, we exploited the special quasi-random structure approach on selected supercells. The cobalt removal was modeled by the simultaneous substitution with Mn/Ni, thus leading to a p-doping in the lattice. Our results show that cobalt removal induces (a) larger cell volumes, originating from expanded distances among stacked planes; (b) a parallel increase of the layer buckling; (c) an increase of the electronic disorder and of the concentration of Jahn–Teller defects; and (d) an increase of the thermodynamic stability of the phase. Overall p-doping appears as a balanced strategy to remove cobalt from LRLO without massively deteriorating the structural integrity and the electronic properties of LRLO.

Protoplasmic streaming of chloroplasts enables rapid photoacclimation in large diatoms

Abstract Long-term (2004–2020) studies showed yearly summer/autumn blooms in the NE Black Sea dominated by large (cell volume &amp;gt; 5000 μm3) diatoms (Pseudosolenia calcar-avis and Proboscia alata). This phenomenon is characterized by high (&amp;gt;250 W m−2 photosynthetically active radiation, PAR) insolation, and low phosphorus concentrations (to analytical zero). These diatoms contained &amp;gt;100 chloroplasts per cell, which at low irradiance are evenly distributed throughout the cell. As light increases (to 1000 μmol photons m−2 s−1 PAR), chloroplasts aggregate within 20 min, usually to the center of the cell. In consequence, the light absorption coefficient is decreased by &amp;gt;3 fold. At elevated photon flux density (PFD), P. calcar-avis also shows a “conveyor” of chloroplasts moving from the aggregate to the cell periphery and back. This mechanism enables a continuous fine-tuning of the cells’ ability to absorb light, likely also facilitating photo-damage repair. This rapid photoacclimation mechanism allows large diatoms to minimize photodamage at high PFD and acclimate well to low PFD. We hypothesize that competitive success of large diatoms in conditions of high light gradients is aided by this short-term rapid photoacclimation enhancing growth rate while minimizing chloroplast repair costs, aided by the ability of large cells to accumulate nutrients for chloroplast synthesis.

Anomalous structural behavior and antiferroelectricity in BiGdO3: detailed temperature and high-pressure study

A comprehensive temperature and high-pressure investigation on BiGdO3 is carried out by means of dielectric constant, piezoelectric current, polarization-electric field loop, Raman scattering and x-ray diffraction measurements. Temperature dependent dielectric constant and dielectric loss show two anomalies at about 290 K (T r) and 720 K (T C). The latter anomaly is most likely due to antiferroelectric to paraelectric transition as hinted by piezoelectric current and polarization-electric field loop measurements at room temperature, while the former anomaly suggests reorientation of polarization. A small deviation from linear behaviour of both the Raman modes due to structural modification in the vicinity of T C; and sharp decrease in integrated intensities of these two modes above T C provide further proof for the above antiferroelectric to paraelectric transition. Cubic to monoclinic structural transition is observed at about 10 GPa in high-pressure x-ray diffraction studies accompanied by anisotropic lattice parameter changes and large unit cell volume collapse during the transition. This structural transition is corroborated by anomalous softening and large increase in full width half maximum of M2 (640 cm−1) Raman mode above 10 GPa. We speculate that enhancement of large structural distortion and large reduction in c/a ratio above 10 GPa might be associated with antiferroelectric to ferroelectric transition in the system.