Late-stage Growth Research Articles

Polymerization behaviors and branching structural analysis of branched polymers in self-condensing atom transfer radical copolymerization of different inimers

The investigation of the relationship between the structure and properties of branched polymers heavily relies on the branched morphology. In this study, we explored the electron-rich and electron-poor effects that arise from different types of double bonds in inimers using self-condensing atom transfer radical polymerization (ATRP). A comparative analysis of polymerization systems using various inimers as branching monomers revealed notable differences. Specifically, when examining styrene-based initiator (St-inimer) systems, the absence of a discernible nucleation feature and the non-conformance to the “core-first-arm-later” method for synthesizing star-shaped polystyrene (branching morphology factor ε is higher than 1.0) were observed. On the other hand, the methacrylate-based initiator (MA-inimer) systems exhibited a clear nucleation process during polymerization, followed by linear molecular weight growth and a constant polydispersity characteristic, consistent with the “core-first-arm-later” approach for synthesizing star-shaped polystyrene (ε is about 0.6, lower than 1.0). The maleimide-based initiator (Mal-inimer) systems demonstrated an initial nucleation phase, a mid-stage linear growth phase with a constant polydispersity characteristic, and a late-stage nonlinear growth phase resulting in a broader polydispersity index. As a result, the polymerization process in maleimide-based initiator systems conforms to the law of preparing star branched polymers with multi-core structures (ε is about 0.8).

Enhanced biomass production and harvesting efficiency of Chlamydomonas reinhardtii under high-ammonium conditions by powdered oyster shell

Chlamydomonas reinhardtii prefers ammonium (NH4+) as a nitrogen source, but its late-stage growth under high-NH4+ concentrations (0.5 ∼ 1 g/L) is retarded due to medium acidification. In this study, oyster shell powders were shown to increase the tolerance of C. reinhardtii to NH4+ supplementation at 0.7 g/L in TAP medium in 1-L bubble-column bioreactors, resulting in a 22.9 % increase in biomass production, 62.1 % rise in unsaturated fatty acid accumulation, and 19.2 % improvement in harvesting efficiency. Powdered oyster shell mitigated medium acidification (pH 7.2–7.8) and provided dissolved inorganic carbon up to 8.02 × 103 μmol/L, facilitating a 76.3 % NH4+ consumption, release of up to 189 mg/L of Ca2+, a 42.1 % reduction in ζ-potential and 27.7 % increase in flocculation activity of microalgae cells. This study highlights a promising approach to utilize powdered oyster shell as a liming agent, supplement carbon source, and bio-flocculant for enhancing biomass production and microalgae harvesting in NH4+-rich environments.

Notch formation in vertical excavations in a deep hard rock mine and rock stabilization methodologies

This paper presents details of the early to mid-stage deterioration in the form of notch growth of two 3 m diameter bored raises that were excavated and slashed to 7.8 m to serve as an internal shaft (winze). In addition, the long-term deterioration of a series of ore/waste passes that were excavated with the bottom-up Alimak methodology is investigated. These excavations were completed at depths between 1200 and 1915 m below the surface in a hard rock mine in Sudbury, Ontario, Canada. The ability to see a cross-section of fracturing around the bored raises while slashing into them and observing the progressive growth of fractures was critical for understanding the factors leading to deterioration. The Alimak-driven ore/waste passes were in an advanced state of deterioration, which provided a late-stage notch growth profile that could be compared with the notch growth observed in the bored raises. The methods used to support and stabilize these excavations are detailed; in addition, methodologies to prevent some of the deterioration from occurring are also presented. The findings of this work are useful for understanding the mechanisms driving brittle rock failure in deep mining and subsequently for minimizing or preventing the deterioration from occurring.

Experimental Study on the Soil Conditions for Rapeseed Transplanting for Blanket Seedling Combined Transplanter

To address the lack of available information on the soil physical conditions suitable for rapeseed blanket-shaped seedling transplanting, as well as the lack of protocols for the optimisation of soil tillage components in the utilisation of an integrated rapeseed blanket seedling combined transplanter, the physical parameters of different soil conditions and their impact on the growth of rapeseed after transplanting were investigated in this study. The aim was to determine the suitable soil physical parameters for rapeseed blanket-shaped seedling transplanting. First, the changes in soil firmness, soil bulk density, and soil moisture content during the installation of the rapeseed blanket seedling combined transplanter were tested and analysed, providing preliminary data for subsequent research. Using the variables of soil firmness and soil moisture content in the micro-environment around the roots and stems (30–50 mm) after rapeseed seedling transplantation and indicators such as the survival rate, root diameter, seedling height, and dry weight, an experiment on the growth of rapeseed blanket-shaped seedlings was conducted based on the furrow cutting transplanting principle. The results indicated that during the initial stage of rapeseed transplanting, the soil moisture content significantly influenced the vitality of the rapeseed plants. Under a high soil moisture content, the typically lengthy seedling period was shortened, and the effect on vitality was good, with minimal influence from the soil firmness. After seedling establishment, the rapeseed growth was significantly affected by the soil firmness. When the soil moisture content was less than 20%, increasing the soil firmness to 500 kPa was beneficial for moisture retention and rapeseed seedling growth. At a soil moisture content ranging from 20 to 25%, a soil firmness of 400 kPa was most suitable for both rapeseed vitality and late-stage growth. When the soil moisture content exceeded 25%, reducing the soil firmness to 300 kPa was beneficial for rapeseed growth, as an excessively high moisture content may lead to soil compaction, affecting seedling development. This study provides a theoretical basis for optimizing the design of soil tillage components in the application of an integrated rapeseed blanket seedling combined transplanter and for the high-yield management of rapeseed after transplanting.

Effects of reverberating waves and interface coupling on a divergent Richtmyer–Meshkov instability

Shock-tube experiments on Richtmyer–Meshkov (RM) instability at a perturbed SF $_6$ layer surrounded by air, induced by a cylindrical divergent shock, are reported. To explore the effects of reverberating waves and interface coupling on instability growth, gas layers with various shapes are created: unperturbed inner interface and sinusoidal outer interface (case US); sinusoidal inner and outer interfaces that have identical phase (case IP); sinusoidal inner and outer interfaces that have opposite phase (case AP). For each case, three thicknesses are considered. Results show that reverberating waves inside the layer dominate the early-stage instability growth, while interface coupling dominates the late-stage growth. The influences of waves on divergent RM instability are more pronounced than the planar and convergent counterparts, which are estimated accurately based on gas dynamics theory. Both the wave influence and interface coupling depend heavily on the layer shape, leading to diverse growth rates: the quickest growth for case AP, medium growth for case US, the slowest growth for case IP. In particular, for the IP case, there exists a critical thickness below which the instability growth is suppressed by both the reverberating waves and interface coupling. This provides an efficient way to modulate the growth of divergent RM instability. It is found that divergent RM instability involves weak nonlinearity and strong interface coupling such that the linear theory of Mikaelian (Phys. Fluids, vol. 17, 2005, 094105) can well reproduce the instability growth at late stages for all cases. This constitutes the first experimental confirmation of the Mikaelian theory.

Scaling laws of plume-induced granular cratering.

Extraterrestrial landing often requires firing a high-speed plume towards a planetary surface, and the resulting gas-granular interactions pose potential hazards to the lander. To investigate these jet-induced cratering dynamics, an experiment campaign covering a range of gas and granular properties relevant to the lunar and Martian environments was conducted in a large-scale vacuum chamber. Despite the variations in jet Mach number, mass flow rate, and composition of the granular phase investigated in this work, the observed time evolution of crater depth displays a consistent transition from an early-stage linear to a late-stage sublinear growth. To explain these scaling relations, a model that relates the kinetic energy gained by the particles per unit time to the power of the impinging jet is introduced. From this model, erosion rates and the critical depth at which the transition occurs can be extracted, and they are shown to depend on the gas impingement pressure, which was varied by changing ambient pressure, jet Mach number, mass flow rate, and nozzle height above the surface. These results highlight key mechanisms at work in the dynamics of plume-induced cratering and help to develop an understanding of optimal rocket engine firing times for future landings.

PdGpaA controls the growth and virulence of Penicillium digitatum by regulating cell wall reorganization, energy metabolism, and CDWEs production

Penicillium digitatum could infect citrus and cause devastating green mold disease. One of the essential parts of the G protein is the Gα subunit, which is essential to signal transduction in filamentous fungi but has not been reported in P. digitatum. In this study, PdGpaA was identified as a homolog of Gα in P. digitatum, and deletion of the PdGpaA gene significantly accelerated early-stage spore germination and inhibited late-stage hyphal growth and conidiophore formation. The ΔPdGpaA strain showed faster growth in sodium dodecyl sulfate (SDS) and calcofluor white (CFW) but more sensitivity to Congo red (CR). We predicted that cell wall integrity had been compromised due to cell wall rearrangement. Moreover, the increased quantity of septa and the reorganization of cell walls were confirmed by CFW staining and quantitative real-time PCR analysis. Deletion of the PdGpaA gene increased intracellular reactive oxygen species (ROS)and mitochondrial deterioration, which obstruct the TCA cycle and hinder energy metabolism. A pathogenicity test revealed that the lesion diameter was decreased by 90.62 % in the ΔPdGpaA strain, probably as the result of a decline in the activity of pectinase and cellulase. In addition, the ΔPdGpaA strain was more sensitive to prochloraz, KCl and H2O2. In conclusion, this study provides multiple functions for the PdGpaA gene, which might have broad application space and prospects in the control of citrus green mold.

Batch-Operated Condensed Droplet Polymerization to Understand the Effect of Temperature on the Size Distribution of Polymer Nanodomes

Size-controlled polymer nanodomes (PNDs) benefit a broad cross-section of existing and emerging technologies. Condensed droplet polymerization (CDP) is a vacuum-based synthesis technology that produces PNDs from monomer precursors in a single step. However, the effect of synthesis and processing conditions on the PND size distribution remains elusive. Towards size distribution control, we report the effect of substrate temperature, on which monomer droplets condense, on the size distribution of PNDs. We take a reductionist approach and operate the CDP under batch mode to match the conditions commonly used in condensation research. Notably, despite the rich knowledge base in dropwise condensation, the behavior of nonpolar liquids like a common monomer, i.e., 2-hydroxyethyl methacrylate (HEMA), is not well understood. We bridge that gap by demonstrating that dropwise condensation of HEMA follows a two-stage growth process. Early-stage growth is dominated by drop nucleation and growth, giving rise to relatively uniform sizes with a lognormal distribution, whereas late-stage growth is dominated by the combined effect of drop coalescence and renucleation, leading to a bimodal size distribution. This new framework for understanding the PND size distribution enables an unprecedented population of PNDs. Their controlled size distribution has the potential to enable programmable properties for emergent materials.

Immunohistochemical localization of kisspeptin and kisspeptin receptor in the equine ovary: Effect of follicle size and reproductive state

Kisspeptin is considered a regulator of reproduction by stimulating GnRH; however, extra-hypothalamic actions of kisspeptin have been described. The aim of this study was to localize kisspeptin-10 (Kp10) and kisspeptin receptor (Kiss1r) in the ovary and compare staining intensity between follicles in follicular-phase (FP) and luteal-phase (LP) ovaries, as well as between seasonally anovulatory (SA) ovaries and ovaries from mares induced to cycle in winter with estradiol cypionate (ECP) and sulpiride. Eight ovaries were collected from light-horse mares during the breeding and non-breeding seasons and characterized as FP (n = 3), LP (n = 2), or SA (n = 3). Additionally, 3 ovaries were collected from SA mares treated with ECP and sulpiride upon detection of the first 30-mm follicle after treatment. Immunohistochemistry was carried out on whole-ovarian, paraffin-embedded sections using anti-Kp10 and anti-Kiss1r antibodies validated on equine hypothalamus. Staining intensity was evaluated in primordial, preantral, and antral follicles using a scale of 0-3. Given a normal distribution, two-way ANOVA was used to compare staining between follicle sizes and reproductive states. Staining for Kp10 and Kiss1r was detected in all follicle sizes throughout all reproductive states, as well as in oocytes and corpora lutea. Staining intensity for both differed between all follicle sizes and was greatest (P < 0.01)in antral follicles. Staining for Kp10 and Kiss1r was similar in preantral follicles of all reproductive states but was greater (P < 0.01) than primordial follicles. In primordial follicles, staining for Kp10 and Kiss1r was greatest (P < 0.01) in ECP-sulpiride stimulated ovaries, but similar between all other states. Kisspeptin-10 and Kiss1r staining was greatest (P < 0.01) in antral follicles of FP and ECP-sulpiride stimulated ovaries. Additional quantification of Kp10 and Kiss1r immunostaining in granulosa cells (GC) of antral follicles was achieved by evaluating three random, 625 μm2 fields in 2-3 follicles per animal in each reproductive state. Color deconvolution of standardized images was performed, and units of intensity converted to optical density and compared by ANOVA. Staining for both Kp10 and Kiss1r was most intense in GC of FP and ECP-sulpiride-stimulated ovaries and was greater (P < 0.0001) than LP and SA ovaries. No differences were detected between LP and SA. Here we characterize, for the first time, Kp10 and Kiss1r in the equine ovary. Staining intensity for both increased as follicle size increased. Staining was greatest in GC of FP ovaries, indicating a potential mechanistic role for kisspeptin during late-stage follicle growth and perhaps ovulation. Furthermore, staining in ECP-sulpiride stimulated ovaries was similar to FP ovaries, providing evidence that treatment with ECP-sulpiride during seasonal anovulation restored ovarian kisspeptin activity to a FP-like state.

The Response of Sugar Beet (Beta vulgaris L.) Genotypes at Different Ploidy Levels to Salt (NaCl) Stress

Sugar beet (Beta vulgaris L.) is cultivated in temperate climates worldwide to produce sugar. The production of sugar beet and other plants is in danger due to the world’s increasingly salinized soils. Although different sugar beet genotypes exist at various ploidy levels, most of them are diploid (2X) with 18 chromosomes. The majority of polyploid plants have different variations, morphologies, and anatomy. Diploid and polyploid plants especially have different morphology, physiology, cellularity, and biochemistry. As a result, polyploidy has been identified as an essential component in determining plant salt tolerance. To evaluate the effects of salt (NaCl) stress on sugar beet genotypes, diploid (2X), triploid (3X), and tetraploid (4X) genotypes were exposed to 0 (control), 50, and 150 mM NaCl concentrations for seven weeks. Under control conditions, the diploid (2X) genotype showed higher growth performance compared to the tetraploid (4X) and triploid (3X) genotypes, respectively. Regarding germination and early-stage growth performance, a reduction of about 50% was observed in the diploid (2X) genotype under salt stress compared to the control condition. The diploid (2X) genotype showed higher germination, a greater salt tolerance index, and better seedling growth performance than the other ploidy levels. Late-stage growth, leaf length, leaf width, leaf area, cytological findings, and total chlorophyll content were all shown to be higher and less reduced (around 30%) under salt stress in diploid (2X) genotypes. Even though all of the findings in this study showed a decrease when plants were exposed to salt (NaCl), the diploid (2X) ploidy level plants displayed more robust growth and development than the triploid (3X) and tetraploid (4X) genotypes.

Differential Virulence Contributions of the Efflux Transporter MexAB-OprM in Pseudomonas syringae Infecting a Variety of Host Plants.

Efflux transporters such as MexAB-OprM contribute to bacterial resistance to diverse antimicrobial compounds. Here, we show that MexB contributes to epiphytic and late-stage apoplastic growth of Pseudomonas syringae strain B728a, as well as lesion formation in common bean (Phaseolus vulgaris). Although a ∆mexB mutant formed fewer lesions after topical application to common bean, these lesions contain the same number of cells (105 to 107 cells) as those caused by the wild-type strain. The internalized population size of both the wild-type and the ∆mexB mutant within small samples of surface-sterilized asymptomatic portions of leaves varied from undetectably low to as high as 105 cells/cm2. Localized bacterial populations within individual lesions consistently exceeded 105 cells/cm2. Strain B728a was capable of moderate to extensive apoplastic growth in diverse host plants, including lima bean (P. lunatus), fava bean (Vicia faba), pepper (Capsicum annuum), Nicotiana benthamiana, sunflower (Helianthus annuus), and tomato (Solanum lycopersicum), but MexB was not required for growth in a subset of these plant species. A model is proposed that MexB provides resistance to as-yet-unidentified antimicrobials that differ between plant species. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

On the extrinsic Hall-Petch to inverse Hall-Petch transition in nanocrystalline Ni-Co electrodeposits

The Hall-Petch to inverse Hall-Petch (HP-IHP) transition of an electrodeposited nanocrystalline Ni-32at%Co alloy was examined by annealing the as-plated alloy to obtain grain sizes ranging between 18 – 239 nm. We describe this transition as an extrinsic HP-IHP transition (extrinsic to the fabrication process) as opposed to the intrinsic HP-IHP transition observed in materials in their as-plated state (intrinsic to the fabrication process). The extrinsic transition of the Ni-32at%Co alloy took place in the mid-stage of abnormal grain growth, at an average grain size of ∼30 nm. Grain boundary relaxation governs the IHP region and maximum hardness was achieved at initial development of bimodal grain size; meanwhile late-stage abnormal grain growth and further normal grain growth led to the reduction in hardness in the HP region. Segregation of sulfur impurities to grain boundaries, crystallographic orientation and annealed twin development did not have significant contributions to the observed change in hardness.

Lithium in garnet as a tracer of subduction zone metamorphic reactions: The record in ultrahigh-pressure metapelites at Lago di Cignana, Italy

Abstract Lithium is of great interest as a tracer of metamorphic reactions and related fluid-mineral interactions because of its potential to isotopically fractionate during inter- and intracrystalline diffusional processes. Study of its transfer through subduction zones, based on study of arc volcanic and metamorphic rocks, can yield insight regarding ocean-to-mantle chemical cycling. We investigated major- and trace-element concentrations and δ7Li in garnet in ultrahigh-pressure (UHP) Lago di Cignana metasedimentary rocks, relating these observations to reconstructed prograde devolatilization history. In all garnet crystals we studied, heavy rare earth elements (HREEs), Y, and Li showed strong zoning, with elevated concentrations in cores (15–50 ppm Li) and marked high-concentration anomalies (up to 117 ppm Li, 5500 ppm Y; little or no major-element shift) as growth annuli, in which some crystals showed subtle elevation in δ7Li greater than analytical error of ~3% (2σ). Rutile inclusions appeared abruptly at annuli and outward toward rims, accompanied by inclusions of a highly zoned, Ca- and rare earth element–rich phase and decreased Nb concentrations in garnet. These relationships are interpreted to reflect prograde garnet-forming reaction(s), in part involving titanite breakdown to stabilize rutile, which resulted in delivery of more abundant Y and HREEs at surfaces of growing garnet crystals to produce annuli. Co-enrichments in Li and Y + REEs are attributed to mutual incorporation via charge-coupled substitutions; thus, increased Li uptake was a passive consequence of elevated concentrations of Y + REEs. The small-scale fluctuations in δ7Li (overall range of ~9%) observed in some crystals may correlate with abrupt shifts in major- and trace-element concentrations, suggesting that changes in reactant phases exerted some control on the evolution of δ7Li. For one garnet crystal, late-stage growth following partial resorption produced deviation in major- and trace-element compositions, including Li concentration, accompanied by a 10%–15% negative shift in δ7Li, perhaps reflecting a change in the mechanism of incorporation or source of Li. These results highlight the value of measuring the major- and trace-element and isotope compositions of garnets in high-pressure and UHP metamorphic rocks in which matrix mineral assemblages are extensively overprinted by recrystallization during exhumation histories. Lithium concentrations and isotope compositions of the garnets can add valuable information regarding prograde (and retrograde) reaction history, kinetics of porphyroblast growth, intracrystalline diffusion, and fluid-rock interactions. This work, integrated with previous study of devolatilization in the Schistes Lustrés/Cignana metasedimentary suite, indicates retention of a large fraction of the initially subducted sedimentary Li budget to depths approaching those beneath volcanic fronts, despite the redistribution of this Li among mineral phases during complex mineral reaction histories.

The VarA-CsrA regulatory pathway influences cell shape in Vibrio cholerae.

Despite extensive studies on the curve-shaped bacterium Vibrio cholerae, the causative agent of the diarrheal disease cholera, its virulence-associated regulatory two-component signal transduction system VarS/VarA is not well understood. This pathway, which mainly signals through the downstream protein CsrA, is highly conserved among gamma-proteobacteria, indicating there is likely a broader function of this system beyond virulence regulation. In this study, we investigated the VarA-CsrA signaling pathway and discovered a previously unrecognized link to the shape of the bacterium. We observed that varA-deficient V. cholerae cells showed an abnormal spherical morphology during late-stage growth. Through peptidoglycan (PG) composition analyses, we discovered that these mutant bacteria contained an increased content of disaccharide dipeptides and reduced peptide crosslinks, consistent with the atypical cellular shape. The spherical shape correlated with the CsrA-dependent overproduction of aspartate ammonia lyase (AspA) in varA mutant cells, which likely depleted the cellular aspartate pool; therefore, the synthesis of the PG precursor amino acid meso-diaminopimelic acid was impaired. Importantly, this phenotype, and the overall cell rounding, could be prevented by means of cell wall recycling. Collectively, our data provide new insights into how V. cholerae use the VarA-CsrA signaling system to adjust its morphology upon unidentified external cues in its environment.

Genetic and lipidomic analyses suggest that Nostoc punctiforme, a plant-symbiotic cyanobacterium, does not produce sphingolipids

Sphingolipids, a class of amino-alcohol-based lipids, are well characterized in eukaryotes and in some anaerobic bacteria. However, the only sphingolipids so far identified in cyanobacteria are two ceramides (i.e., an acetylsphingomyelin and a cerebroside), both based on unbranched, long-chain base (LCB) sphingolipids in Scytonema julianum and Moorea producens , respectively. The first step in de novo sphingolipid biosynthesis is the condensation of l-serine with palmitoyl-CoA to produce 3-keto-diyhydrosphingosine (KDS). This reaction is catalyzed by serine palmitoyltransferase (SPT), which belongs to a small family of pyridoxal phosphate-dependent α-oxoamine synthase (AOS) enzymes. Based on sequence similarity to molecularly characterized bacterial SPT peptides, we identified a putative SPT (Npun_R3567) from the model nitrogen-fixing, plant-symbiotic cyanobacterium, Nostoc punctiforme strain PCC 73102 (ATCC 29133). Gene expression analysis revealed that Npun_R3567 is induced during late-stage diazotrophic growth in N. punctiforme . However, Npun_R3567 could not produce the SPT reaction product, 3-keto-diyhydrosphingosine (KDS), when heterologously expressed in Escherichia coli . This agreed with a sphingolipidomic analysis of N. punctiforme cells, which revealed that no LCBs or ceramides were present. To gain a better understanding of Npun_R3567, we inferred the phylogenetic position of Npun_R3567 relative to other bacterial AOS peptides. Rather than clustering with other bacterial SPTs, Npun_R3567 and the other cyanobacterial BioF homologues formed a separate, monophyletic group. Given that N. punctiforme does not appear to possess any other gene encoding an AOS enzyme, it is altogether unlikely that N. punctiforme is capable of synthesizing sphingolipids. In the context of cross-kingdom symbiosis signalling in which sphingolipids are emerging as important regulators, it appears unlikely that sphingolipids from N. punctiforme play a regulatory role during its symbiotic association with plants.

Metformin induces lactate accumulation and accelerates renal cyst progression in Pkd1-deficient mice.

Metabolic reprogramming is a potential treatment strategy for autosomal dominant polycystic kidney disease (ADPKD). Metformin has been shown to inhibit the early stages of cyst formation in animal models. However, metformin can lead to lactic acidosis in diabetic patients with advanced chronic kidney disease, and its efficacy in ADPKD is still not fully understood. Here, we investigated the effect of metformin in an established hypomorphic mouse model of PKD that presents stable and heritable knockdown of Pkd1. The Pkd1 miRNA transgenic mice of both genders were randomized to receive metformin or saline injections. Metformin was administrated through daily intraperitoneal injection from postnatal day 35 for 4weeks. Unexpectedly, metformin treatment at a concentration of 150mg/kg increased disease severity, including kidney-to-body weight ratio, cystic index and plasma BUN levels, and was associated with increased renal tubular cell proliferation and plasma lactate levels. Functional enrichment analysis for cDNA microarrays from kidney samples revealed significant enrichment of several pro-proliferative pathways including β-catenin, hypoxia-inducible factor-1α, protein kinase Cα and Notch signaling pathways in the metformin-treated mutant mice. The plasma metformin concentrations were still within the recommended therapeutic range for type 2 diabetic patients. Short-term metformin treatment in a second Pkd1 hypomorphic model (Pkd1RC/RC) was however neutral. These results demonstrate that metformin may exacerbate late-stage cyst growth associated with the activation of lactate-related signaling pathways in Pkd1 deficiency. Our findings indicate that using metformin in the later stage of ADPKD might accelerate disease progression and call for the cautious use of metformin in these patients.

Shallow magmatic processes revealed by cryptic microantecrysts: a case study from the Taupo Volcanic Zone

Arc magmas typically contain phenocrysts with complex zoning and diverse growth histories. Microlites highlight the same level of intracrystalline variations but require nanoscale resolution which is globally less available. The southern Taupo Volcanic Zone (TVZ), New Zealand, has produced a wide range of explosive eruptions yielding glassy microlite-bearing tephras. Major oxide analyses and textural information reveal that microlite rims are commonly out of equilibrium with the surrounding glass. We mapped microlites and microcrysts at submicron resolution for major and trace element distributions and observed three plagioclase textural patterns: (1) resorption and overgrowth, (2) oscillatory zoning, and (3) normal (sharp) zoning. Pyroxene textures are diverse: (1) resorption and overgrowth, (2) calcium-rich bands, (3) hollow textures, (4) oscillatory zoning, (5) sector zoning, (6) normal zoning and (7) reverse zoning. Microlite chemistry and textures inform processes operating during pre-eruptive magma ascent. They indicate a plumbing system periodically intruded by short-lived sub-aphyric dykes that entrain microantecrysts grown under diverse physico-chemical conditions and stored in rapidly cooled, previously intruded dykes. Changes in temperature gradients between the intrusion and the host rock throughout ascent and repeated magma injections lead to fluctuations in cooling rates and generate local heterogeneities illustrated by the microlite textures and rim compositions. Late-stage degassing occurs at water saturation, forming thin calcic microcryst rims through local partitioning effects. This detailed investigation of textures cryptic to conventional imaging shows that a significant proportion of the micrometre-sized crystal cargo of the TVZ is of antecrystic origin and may not be attributed to late-stage nucleation and growth at the onset of volcanic eruptions, as typically presumed.

Agro-Economic Evaluation of Alternative Crop Management Options for Teff Production in Midland Agro-Ecology, Ethiopia

Teff is an important crop for smallholder farmers in Ethiopia. Improved crop management practices are needed to increase teff productivity and decrease production costs. Here, we used a split–split plot design to evaluate the impacts of different tillage, sowing, and soil compaction practices, and their combinations, on agronomic performance, weed population, lodging, and cost in teff production at the Aba Gerima watershed in northwestern Ethiopia in 2018–2020. Reduced tillage (RT) improved soil moisture, resulting in increased agronomic performance and decreased production costs compared with conventional tillage (CT); however, the weed population was substantially larger with RT than with CT. Row planting (RP) reduced seed cost and lodging but increased sowing and weeding costs compared with broadcast planting (BP). Plant population and leaf area index were substantially greater with BP than with RP during early-stage growth, but this reversed during late-stage growth. Despite labor costs being significantly greater with (WC) compaction than without (NC), little to no differences were observed in the weed population or in agronomic performance. Partial cost–benefit analysis revealed that RT–RP–WC followed by RT–RP–NC was the most economical treatment combination, suggesting that RT–RP–NC could be a labor-effective means of increasing teff production by smallholder farms in Ethiopia.

Omega-3 Eicosapentaenoic Acid Reduces Prostate Tumor Vascularity.

The impact of omega (ω)-3 fatty acids on prostate cancer is controversial in epidemiological studies but experimental studies suggest a protective effect. However, little is known about the mechanism of action. Here, we studied the effects of purified fatty acid molecules on prostate tumor progression using the TRAMP-C2 syngeneic immunocompetent mouse model. Compared with ω-6 or ω-9-supplemented animals, we observed that late-stage prostate tumor growth was reduced with a monoacylglyceride (MAG)-conjugated form of eicosapentaenoic acid (EPA) supplementation, whereas docosahexanenoic acid (DHA) caused an early reduction. MAG-EPA significantly decreased tumor blood vessel diameter (P < 0.001). RNA sequencing analysis revealed that MAG-EPA downregulated angiogenesis- and vascular-related pathways in tumors. We also observed this tissue vascular phenotype in a clinical trial testing MAG-EPA versus a high oleic sunflower oil placebo. Using anti-CD31 IHC, we observed that MAG-EPA reduced blood vessel diameter in prostate tumor tissue (P = 0.03) but not in normal adjacent tissue. Finally, testing autocrine and paracrine effects in an avascular tumor spheroid growth assay, both exogenous MAG-EPA and endogenous ω3 reduced VEGF secretion and in vitro endothelial cell tube formation and blocked tumor spheroid growth, suggesting that ω3 molecules can directly hinder prostate cancer cell growth. Altogether, our results suggest that fatty acids regulate prostate cancer growth and that a tumor-specific microenvironment is required for the anti-vascular effect of MAG-EPA in patients with prostate cancer. IMPLICATIONS: Increasing the amount of ingested EPA omega-3 subtype for patients with prostate cancer might help to reduce prostate tumor progression by reducing tumor vascularization.

Smoothed particle hydrodynamics simulation of converging Richtmyer–Meshkov instability

The Smoothed Particle Hydrodynamics (SPH) method based on the Harten–Lax–van Leer Riemann solver is improved to study converging Richtmyer–Meshkov instability (RMI). A new density summation algorithm is proposed, which greatly suppresses the pressure oscillation at the material interface. The one-dimensional Sod problem is first simulated for code verification. Then, the SPH program is extended to two dimensions to simulate the converging RMI at a square air/SF6 interface, and the numerical results compare well with the experimental ones [Si et al., “Experimental investigation of cylindrical converging shock waves interacting with a polygonal heavy gas cylinder,” J. Fluid Mech. 784, 225–251 (2015)]. Nonlinear mode coupling and pressure disturbance are found to act evidently, causing a very fast growth spike. Performing a Fourier analysis of the interface profiles, amplitude growths of the first three harmonics are obtained. The first harmonic presents an increasing growth rate at early stages due to geometric convergence. The second harmonic experiences a long period of linear growth due to the counteraction between geometric convergence and nonlinearity, whereas the third harmonic saturates very early for stronger nonlinearity. For all three harmonics, the perturbation growth rate reduces evidently at the late stage due to the Rayleigh–Taylor stabilization caused by interface deceleration. It is found that the instability growth at early stages depends heavily on the incident shock strength, while the late-stage asymptotic growth rate is nearly constant, regardless of shock strength. It is also found that intensifying the incident shock is an effective way to produce extreme thermodynamic state at the geometric center even though it causes a faster instability growth.