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Developing a system for in vivo imaging of maize roots containing iodinated contrast media in soil using synchrotron XCT and XRF
We sought to develop a novel experimental system which enabled application of iodinated contrast media to in vivo plant roots intact in soil and was compatible with time-resolved synchrotron X-ray computed tomography imaging. The system was developed to overcome issues of low contrast to noise within X-ray computed tomography images of plant roots and soil environments, the latter of which can complicate image processing and result in the loss of anatomical information. To demonstrate the efficacy of the system we employ the novel use of both synchrotron X-ray computed tomography and synchrotron X-ray fluorescence mapping to capture the translocation of the contrast media through root vasculature into the leaves. With the application of contrast media we identify fluid flow in root vasculature and visualise anatomical features, which are otherwise often only observable in ex vivo microscopy, including: the xylem, metaxylem, pith, fibres in aerenchyma and leaf venation. We are also able to observe interactions between aerenchyma cross sectional area and solute transport in the root vasculature with depth. Our novel system was capable of successfully delivering sufficient contrast media into root and leaf tissues such that anatomical features could be visualised and internal fluid transport observed. We propose that our system could be used in future to study internal plant transport mechanisms and parameterise models for fluid flow in plants.
Carotenoid to bacteriochlorophyll energy transfer in the RC–LH1–PufX complex from Rhodobacter sphaeroides containing the extended conjugation keto-carotenoid diketospirilloxanthin
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Ca2+ Effects on Fe(II) Interactions with Mn-Binding Sites in Mn-Depleted Oxygen-Evolving Complexes of Photosystem II and on Fe Replacement of Mn in Mn-Containing, Ca-Depleted Complexes
Fe(II) cations bind with high efficiency and specificity at the high-affinity (HA), Mn-binding site (termed the “blocking effect” since Fe blocks further electron donation to the site) of the oxygen-evolving complex (OEC) in Mn-depleted, photosystem II (PSII) membrane fragments (Semin et al. in Biochemistry 41:5854, 2002). Furthermore, Fe(II) cations can substitute for 1 or 2Mn cations (pH dependent) in Ca-depleted PSII membranes (Semin et al. in Journal of Bioenergetics and Biomembranes 48:227, 2016; Semin et al. in Journal of Photochemistry and Photobiology B 178:192, 2018). In the current study, we examined the effect of Ca2+ cations on the interaction of Fe(II) ions with Mn-depleted [PSII(-Mn)] and Ca-depleted [PSII(-Ca)] photosystem II membranes. We found that Ca2+ cations (about 50 mM) inhibit the light-dependent oxidation of Fe(II) (5 µM) by about 25% in PSII(-Mn) membranes, whereas inhibition of the blocking process is greater at about 40%. Blocking of the HA site by Fe cations also decreases the rate of charge recombination between QA- and YZ•+ from t1/2?=?30 ms to 46 ms. However, Ca2+ does not affect the rate during the blocking process. An Fe(II) cation (20 µM) replaces 1Mn cation in the Mn4CaO5 catalytic cluster of PSII(-Ca) membranes at pH 5.7 but 2 Mn cations at pH 6.5. In the presence of Ca2+ (10 mM) during the substitution process, Fe(II) is not able to extract Mn at pH 5.7 and extracts only 1Mn at pH 6.5 (instead of two without Ca2+). Measurements of fluorescence induction kinetics support these observations. Inhibition of Mn substitution with Fe(II) cations in the OEC only occurs with Ca2+ and Sr2+ cations, which are also able to restore oxygen evolution in PSII(-Ca) samples. Nonactive cations like La3+, Ni2+, Cd2+, and Mg2+ have no influence on the replacement of Mn with Fe. These results show that the location and/or ligand composition of one Mn cation in the Mn4CaO5 cluster is strongly affected by calcium depletion or rebinding and that bound calcium affects the redox potential of the extractable Mn4 cation in the OEC, making it resistant to reduction.
Synthesis of substituted disulfonyl-containing polycyclic azines with the bridgehead nitrogen atom. Effects of the structure of 3-substituted pyridinium ylides on the regioselectivity of their reactions with E-1,2-di(alkylsulfonyl)-1,2-dichloroethenes
Heating the substituted pyridinium and isoquinolinium salts with E-1,2-di(alkylsulfonyl)-1,2-dichloroethenes in either chloroform or acetone in the presence of three-fold excess of Et{sub 3}N gave high yields of substituted 1,2-di(alkylsulfonyl)indolizines and 1,2-di(alkylsulfonyl) pyrrolo[2,1-a]isoquinolines, respectively. Effects of the structure of 3-substituted pyridinium ylides on the regioselectivity of their reaction with E-1,2-di(alkylsulfonyl)-1,2-dichloroethenes were revealed. It was shown that the presence of electron-releasing and electron-withdrawing substituents in the pyridinium ylide favors the formation of 8-substituted and 6-substituted 1,2-(dialkylsulfonyl)indolizines, respectively.
Cryochemical synthesis and antibacterial activity of hybrid nanocomposites based on dioxidine containing Ag and Cu nanoparticles incorporated in biopolymer cryostructurates
Cryochemical synthesis of hybrid nanocomposites based on the antibacterial drug, dioxidine, and metals (Ag, Cu) was performed. According to the data of H{sup 1} NMR, UV, and IR spectroscopy, low-temperature argon sorption, and transmission electron microscopy, met-als in these systems exist as Ag nanoparticles (with dimensions of 2—30 nm) or Cu nanoparti-cles (10—40 nm) involved in the bigger-sized particles of dioxidine with dimensions of 50—350 nm. These hybrid nanocomposites show the enhanced antibacterial activity towards the microbial cells Escherichia coli 52, Staphylococcus aureus 144, Mycobacterium cyaneum 98. The as-prepared drug nanocomposites are incorporated into spongy alginate cryostructurates. The feasibility of drug release from the biopolymer alginate carrier is proved and the related antibacterial activity is demonstrated.
Homoannular disubstituted ruthenocenes containing a trifluoromethyl(tetramethyl)cyclopentadienyl ligand
The reaction of the divalent ruthenium complexes [Cp{sup F}RuCl]{sub n} and [Cp{sup F}Ru(MeCN){sub 3}]PF{sub 6} with substituted pentafulvenes 1,2-(Me{sub 2}NCH)(CO{sub 2}Et)C{sub 5}H{sub 3} and 1,3-(Me{sub 2}NCH)(CO{sub 2}Et)- C{sub 5}H{sub 3} followed by hydrolysis affords new homoannular disubstituted ruthenocenes {1,2- (CO_2Et)(CHO)C_5H_3}RuCp{sup F} and {1,3-(CO_2Et)(CHO)C_5H_3}RuCp{sup F} (Cp{sup F} = C{sub 5}Me{sub 4}CF{sub 3}), re- spectively.
Synthesis and molecular structures of Yb{sup II} and Ca bis(amidinate) complexes containing the tridentate amidinate ligand [2,6-Pr{sup i}{sub 2}C{sub 6}H{sub 3}NC(But)NC{sub 6}H{sub 4}OMe-2]
New bis(amidinate) complexes of calcium, [2,6-Pr{sup i}{sub 2}C{sub 6}H{sub 3}NC(But)NC{sub 6}H{sub 4}OMe-2]{sub 2}Ca(DME) (2), and divalent ytterbium, [2,6-Pr{sup i}{sub 2}C{sub 6}H{sub 3}NC(But)NC{sub 6}H{sub 4}OMe-2]{sub 2}Yb (4), were synthesized by the transamination of the bis(amide) derivatives [(Me{sub 3}Si){sub 2}N]{sub 2}M(THF){sub 2} (M = Ca, Yb) with two equivalents of amidine 2,6-Pr{sup i}{sub 2}C{sub 6}H{sub 3}N=C(But)N(H)C{sub 6}H{sub 4}OMe-2, in which one nitrogen atom bears an o-methoxyphenylene moiety capable of coordinating a metalion. An X-ray diffraction study showed that, despite very similar ionic radii of Ca{sup 2+} and Yb{sup 2+}, the amidinate ligands in complexes 2 and 4 bind to these ions in different coordination modes. In the calcium complex, both ligands adopt a κ{sup 2}-N, O-chelating coordination mode. In the divalent ytterbium compound, one ligand is chelating and binds to the metalion in a κ{sup 2}-N, O-coordination mode, while the second ligand is coordinated via both the N and O (κ{sup 2}) atoms and the arene ring of the 2,6-Pr{sup i}{sub 2}C{sub 6}H{sub 3} moiety (η{sup 6}-coordination mode).
Synthesis of novel carborane-containing terminal alkynes
Lithiation of 1-bromomethyl-o-carborane with lithium diisopropylamide (LDA) in THF results in the in situ formation of 1-lithio-2-bromomethyl-o-carborane, the reaction of which with 3-trimethylsilylprop-2-ynal gives 2-(2-trimethylsilylethynyl)-3,4-(о-carborano)-2,5-dihydrofuran. Subsequent base-catalyzed desilylation furnishes new terminal alkynes of closoand nido-carborane series.
Tetrylenes based on 1,10-phenanthroline-containing diol: the synthesis and application as initiators of ε-caprolactone polymerization
Treatment of 4,7-dichloro-2,9-dimethyl-1,10-phenanthroline with two equivalents of p-tert-butylphenol in the presence of К{sub 2}СО{sub 3} afforded 4,7-di(4-tert-butylphenoxy)-2,9-dimethyl-1,10-phenanthroline (1). Monolithiation of 1 with lithium diisopropylamide followed by treatment with benzophenone resulted in 1-(4,7-bis-p-tert-butylphenoxy-9-methyl-1,10- phenanthrolin-2-yl)methyl-1,1-diphenylethanol (2). 1-(4,7-Bis-p-tert-butylphenoxy-9-hydroxy (diphenyl)methyl-1,10-phenanthrolin-2-yl)-1,1-diphenylethanol (3), a tetradentate ONNO ligand, was prepared analogously from 2. The interaction of 3 with 1 eq. of Lappert’s germylene or stannylene M[N(SiMe{sub 3}){sub 2}]{sub 2} (M = Ge, Sn) led to the corresponding germylene 4 and stannylene 5 in moderate yields. According to {sup 1}Н, {sup 13}С, and {sup 119}Sn NMR spectroscopy data, stannylene 5 is monomeric in solution and the coordination number of tin atom is 4. Tetrylenes 4 and 5 demonstrated high activity as initiators of bulk polymerization of ε-caprolactone which leads to high-molecular-weight polymers with relatively narrow molecular weight distribution.
Synthesis, structure, and luminescent properties of lanthanide complexes containing 1,10-phenanthroline and perfluorinated 2-mercaptobenzothiazolate ligands
Mononuclear terbium and erbium complexes of the composition Ln(mbt{sup F}){sub 3}phen and the dinuclear complex Tb{sub 2}(mbt{sup F}){sub 4}(OH){sub 2}(phen){sub 2} (mbt{sup F} is 4,5,6,7-tetrafluoro-2-mercaptobenzothiazolate, phen is 1,10-phenanthroline) were synthesized. The structures of the complexes Er(mbt{sup F}){sub 3}phen and Tb{sub 2}(mbt{sup F}){sub 4}(OH){sub 2}(phen){sub 2} were determined by X-ray diffraction. In the solid state, the terbium and erbium complexes exhibit intense metal-centered photoluminescence. Based on the complexes Ln(mbt{sup F}){sub 3}phen, double-layer organic light-emitting diodes (OLEDs) were assembled. These OLEDs exhibit electroplex emission with a band maximum at 630 nm.
Sterically hindered tetrylenes based on new 1,10-phenanthroline-containing diols: initiators for ε-caprolactone polymerization
Previously unknown tetradentate ONNO-type ligands 1–5 (4,7-di(4-R´-phenoxy)-2,9- di(HOCR{sub 2}CH)-1,10-phenanthrolines (R´ = Me, R–R = –(CH{sub 2}){sub 5}– (1), R = Me (2), R–R = 2,2-adamantylene (3); R´ = But, R–R = –(CH{sub 2}){sub 5}– (4), R = Me (5)) were synthesized by sequential treatment of 2,9-dimethyl-4,7-di(4-R´-phenoxy)-1,10-phenanthrolines 6 (R´ = Me) and 7 (R´ = Bu{sup t}) with excess LDA and appropriate dialkyl ketone. The structure of compound 4 was determined by single-crystal X-ray diffraction. Previously uncharacterized phenanthroline 6 was synthesized by the treatment of 4,7-dichloro-2,9-dimethyl-1,10-phenanthroline with excess p-cresol in the presence of KOH. The reaction of compounds 1–5 with one equivalent of Lappert´s germylene or stannylene, M[N(SiMe{sub 3}){sub 2}]{sub 2} (M = Ge, Sn), gave the corresponding germylenes 8–12 (M = Ge, R´ = Me, R–R = –(CH{sub 2}){sub 5}– (8), R = Me (9), R–R = 2,2-adamantylene (10), R´ = Bu{sup t}, R{sub 2} = –(CH{sub 2}){sub 5}– (11), R = Me (12)) and stannylenes 13–17 (M = Sn, R´ = Me, R–R = –(CH{sub 2}){sub 5}– (13), R = Me (14), R–R = 2,2-adamantylene (15), R´ = Bu{sup t}, R–R = –(CH{sub 2}){sub 5}– (16), R{sub 2} = Me (17)) in satisfactory yields. According to {sup 1}H, {sup 13}C, and {sup 119}Sn NMR data, the synthesized stannylenes are monomeric in solution, and the tin atom has a coordination number of 4. In the series of the compounds under consideration, stannylene 16 proved to be the most active initiator for e-caprolactone polymerization, whereas the germylenes were shown to be inactive in this process.
Substrate-induced luminescence response of terbium-containing polymeric vesicles doped with the tetra- and bis-1,3-diketone derivatives of calix[4]arenes bearing nonyl substituents at the lower rims
Polymeric aggregates (~100 nm) based on polydiacetylenic acid doped with the luminescent Tb{sup III} complexes with the tetra- and bis-1,3-diketonate derivatives of calix[4]arenes with nonyl substituents at the lower rims are considered as potential nanosensors. The obtained colloidally stable mixed aggregates can generate a substrate-induced luminescent response in aqueous solutions of 2,2´,6´,2´´-terpyridine in the micromolar concentration range due to the coordination of the latter by Tb{sup III} ions on the aggregate surface.
Reaction of phenyl-containing N-substituted 1,3-oxazolidines and 1,3-oxazinanes with triammine(tricarbonyl)chromium
New heterocyclic compounds with phenyl chromium tricarbonyl substituents were synthesized by the reaction of triammine(tricarbonyl)chromium with phenyl-substituted 1,3-oxazacy-cloalkanes bearing acetyl, tert-butyloxycarbonyl, or phenyl group at the nitrogen atom. The resulting compounds were isolated in the individual state and characterized by physicochemical methods of analysis.
Photonics of 18-crown-6-containing styryl dye and its complex with cucurbit[7]uril in the presence of lead cation
The photophysical processes and photochemical reactions of 4-[(E)-2-(2,3,5,6,8,9,11,12,14,15-decahydro-1,4,7,10,13,16-benzohexaoxacyclooctadecyn-18-yl)vinyl]-1-ethylpyridinium perchlorate and its complexes with cucurbit[7]uril in water in the absence and in the presence of lead perchlorate were studied by absorption, luminescence, and laser kinetic spectroscopy. Intersystem crossing to the triplet state and trans—cis-photoisomerization of the dye were established. The formation of an inclusion complex of the dye with cucurbit[7]uril was found.
Solid State Reduction Driven Synthesis of Mn Containing Multi-principal Component Alloys
In recent years, high entropy alloys (HEAs), also known as multi-principal component alloys (MPCAs) have emerged as a new and exciting class of materials. This paper reports on the solid state reduction synthesis of a series of CoFeNiMn-based MPCA compositions, starting from a mixture of the corresponding oxides. One of the aims of the study was to test whether the degree of reduction of MnO, a highly stable oxide, could be enhanced by tailoring the alloy composition. Specifically, the influence of Ni content was studied because Ni exhibits a significant negative enthalpy of mixing with Mn. High purity precursor powders of Co(OH) 2 , Fe 2 O 3 , MnO 2 , and NiO were milled and mixed using standard ceramic processing methods. Here, the nominal sample compositions (assuming complete oxide reduction) were (CoFeMn) x Ni (1-x) , for x = 0, 0.083, 0.166, and 0.25. The oxide samples were subjected to a series of isothermal reduction anneals in flowing 3 pct H 2 –Ar at 1100 °C. The resulting microstructures were characterized using scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The composition of the resulting MPCAs was determined quantitatively using wavelength dispersive spectroscopy (WDS) in the electron microprobe. The study revealed that for each of the initial oxide compositions studied, it was possible to achieve an MPCA with ~ 25 at. pct Mn. These results were found to be consistent with the predictions of a thermodynamic model whereby a negative enthalpy of mixing (ΔH mix ), combined with a contribution from configurational entropy, can offset a positive free energy of reduction (ΔG red ). The incorporation of vibrational entropy into first principles calculations was found to have a significant effect on the predicted crystal structure of the MPCAs.
Correction to: Dephosphorization Kinetics between Bloated Metal Droplets and Slag Containing FeO: The Influence of CO Bubbles on the Mass Transfer of Phosphorus in the Metal
An error occurred in the Table VI of this paper. The values used in this paper for diffusivity of phosphorus in the metal phase were incorrectly entered in Table VI. The values should be as listed in the following table.
Kinetics of Transformation of Al{sub 2}O{sub 3} to MgO·Al{sub 2}O{sub 3} Spinel Inclusions in Mg-Containing Steel
During ladle furnace refining, initial Al{sub 2}O{sub 3} inclusions generally transform into MgO·Al{sub 2}O{sub 3} spinel inclusions; these generated spinel inclusions consequently deteriorate the product quality. In this study, the transformation from Al{sub 2}O{sub 3} to MgO·Al{sub 2}O{sub 3} was investigated by immersing an Al{sub 2}O{sub 3} rod into molten steel, which was in equilibrium with both MgO and MgO·Al{sub 2}O{sub 3} spinel-saturated slag. A spinel layer, with a thickness of 4 μm, was generated on the Al{sub 2}O{sub 3} rod surface just 10 s after its immersion at 1873 K (1600 °C). The thickness of the formed spinel layer increased with the immersion period and temperature. Moreover, the MgO content of the generated spinel layer also increased with the immersion period. In this study, the chemical reaction rate at 1873 K (1600 °C) was assumed to be sufficiently high, and only diffusion was considered as a rate-controlling step for this transformation. By evaluating the activation energy, MgO diffusion in the generated spinel layer was found to be the rate-controlling step. In addition, this estimation was confirmed by observing the Mg and Al concentration gradients in the generated spinel layer. The results of this study suggest that the MgO diffusion in the spinel inclusions plays a substantial role with regard to their formation kinetics.