The Development and Lifetime Stability Improvement of Guanosine-Based Supramolecular Hydrogels through Optimized Structure

Guanosine is an important building block for supramolecular gels owing to the unique self-assembly property that results from the unique hydrogen bond acceptors and donor groups. Guanosine-derived supramolecular hydrogels have promise in the fields of drug delivery, targeted release, tissue engineering applications,etc.However, the property of poor longevity and the need for excess cations hinder the widespread applications of guanosine hydrogels. Although guanosine-derived supramolecular hydrogels have been reviewed previously by Dash et al., the structural framework of this review is different, as the modification of guanosine is described at the molecular level. In this review, we summarize the development and lifetime stability improvement of guanosine-based supramolecular hydrogels through optimized structure and elaborate on three aspects: sugar modification, base modification, and binary gels. Additionally, we introduce the concept and recent research progress of self-healing gels, providing inspiration for the development of guanosine-derived supramolecular hydrogels with longer lifespans, unique physicochemical properties, and biological activities.

Phase control of quasi-2D perovskites and improved light-emitting performance by excess organic cations and nanoparticle intercalation

Quasi-2D perovskite phases are controlled by excess cations and zinc oxide (ZnO) nanoparticles, improving the light-emitting performance and device stability.

Mineral nutrient uptake and removal by canola, Indian mustard, and Linola in two contrasting environments, and implications for carbon cycle effects on soil acidification

Field studies of the oilseed crops canola, Indian mustard, and linseed/Linola were conducted over 2 seasons at 2 contrasting sites in the cropping regions of central and southern NSW to determine the uptake of mineral nutrients and quantities removed in seed. The sites were in the Junee region where production of these oilseeds is common, and at Condobolin, which is regarded as marginal for production of the crops. The 2 rates of nitrogen (N) fertiliser applied were either none or rates that growers in the Condobolin and Junee regions would apply to achieve high seed yields after a cereal crop in the rotation when soil mineral N is low. Concentrations of total N, the major cations (K, Ca, Mg, Na) and major anions (P, S, Cl), and the micronutrients Fe, Mn, Zn, and Cu were determined in shoots harvested at flowering and maturity. Nitrate and sulfate were also measured, and estimates were made of excess cation concentrations in the plant material. The ranges of concentrations of excess cations in shoots of the oilseeds at flowering were 83–206 cmolc/kg and 43–121 cmolc/kg for straw at maturity. Linola had lower concentrations of excess cations in vegetative material (83–108 and 43–82 cmolc/kg at flowering and maturity, respectively) than canola or Indian mustard. Concentrations of excess cations in seed of the crops were lower than for vegetative material, and ranged from 30 to 49 cmolc/kg. Nitrogen fertiliser had relatively little effect on concentrations of mineral nutrients or excess cations in either shoots at flowering and maturity, or in seed. However, N fertiliser increased the growth and seed yields of the crops, and thus the amounts of mineral nutrients and excess cations in shoots and seed. The results are discussed in the context of the depletion of soil nutrients due to their removal in harvested seed of the N-fertilised crops. The contribution of excess cation removal in seed to soil acidification is also discussed. It is estimated that the quantity of lime required to neutralise the acidity resulting from removal of 1 t seed is 22.4 kg for canola, 17.0 for Indian mustard, and 20.8 for linseed/Linola. Estimates of the relative contributions of seed removal and N fertiliser to soil acidification are presented.

Effect of short-term legume residue decomposition on soil acidity

The accumulation of organic matter has been suggested to be one of the causes of soil acidification. We examined the effect of applying clover shoots, clover roots, and lupin leaves which differed in concentrations of N and excess cations/ash alkalinity on the pH of 2 acidic soils from Western Australia over a 28-day incubation period. Addition of the legume residues at rates of 1·54 and 3·08 g/kg soil increased soil pH by up to 0·6 units at Day 0 and 0·7 units at Day 28 after incubation. The increase in soil pH was the greatest with addition of lupin leaves, followed by clover shoots, and the least with clover roots. The increase in pH correlated well with the amounts of ash alkalinity added as plant materials. Ammonium concentrations were generally increased by addition of the plant materials, but with time the concentrations decreased in the Kojonup soil and increased in the Moora soil. Nitrate concentrations were similar between the treatments, and increased with time. Addition of legume residues slightly increased the pH buffer capacity of both soils at Day 0 but not at Day 28. After 28 days, 37–51% of clover shoots and 36–51% of lupin leaf had decomposed compared with 22-38% of clover roots. The results suggest that rapid changes in soil pH following application of plant materials are related to the concentration of excess cations and decomposition of the material and that the application of legume shoot residues, which usually have high concentrations of excess cations, is not the likely cause of soil acidification.

Pasture legume species differ in their capacity to acidify soil

The capacity of subterranean clover (Trifolium subterraneum L. cv. Clare), medic (Medicago murex Willd. cv. Zodiac), serradella (Ornithopus sativus Brot. line SP1/13), biserrula (Biserrula pelecinus L. line Mor99), and woolly clover (Trifolium tomentosum L.) to acidify soil under N2 fixation was compared in a pot experiment using a poorly buffered sandy soil. The amount of acid produced per kg shoot dry matter (specific acid production) varied betweefin species and with growth stages, ranging from 44 to 128 cmol/kg shoot. Subterranean clover and serradella acidied soil to a greater extent than woolly clover and medic, whereas biserrula acidified soil least. Irrespective of pasture species and growth stage, specific acid production correlated well with concentrations of excess cations and calcium in shoots. Furthermore, total excess cation, ash alkalinity, and calcium in shoots were all good indicators of total acid production across all of the species.

Factors affecting soil acidification under legumes. II. Effect of phosphorus supply

Phosphorus deficiency is common in crop production. This pot experiment examined whether the supply of Ca(H2PO4)2 affected acid production by N2-fixing plants of 5 grain and 4 pasture legume species grown in a P-deficient sandy soil for 60-64 days. The legume species differed greatly in their response to P application. Lupinus albus, L. luteus, and Biserrula pelecinus were less responsive to P supply than Cicer arietinum, Vicia faba, Medicago polymorpha, Ornithopus sativus, and Trifolium subterraneum, which in turn were less reponsive than L. angustifolius. Increasing P supply up to moderately deficient levels increased the amount of acid production per unit shoot biomass (specific acid production), and further increasing P decreased specific acid production. The effect of species on acid production was greater than the effect of P supply. Among the species, C. arietinum had the highest specific acid production and B. pelecinus the lowest. Specific acid production was correlated with concentrations of excess cations and ash alkalinity as well as Ca and Mg but not P in shoot. There was a very good agreement between total acid production and total content of excess cations in the whole plant, irrespective of P supply and plant species. The results suggest that acid production by legumes under various P supplies is related to the imbalance of cation and anion uptake.

Acidification potential of ten grain legume species grown in nutrient solution

The paper reports the relative acidification potential of 10 N2-fixing grain legume species grown in nutrient solution for 35 days after nodule appearance. The legumes studied were pilosus (Lupinus pilosus Murr. P23342), yellow lupin (Lupinus luteus L. R1171), white lupin (Lupinus albus L. Kiev mutant), narrow-leafed lupin (Lupinus angustifolius L. Gungurru), faba bean (Vicia faba L. Fiord), field pea (Pisum sativum L. Dundale), grasspea (Lathyrus sativus L. S453), chickpea (Cicer arietinum L. T1587), common vetch (Vicia sativa L. Blanchefleur), and lentil (Lens culinaris Med. ILL6002). The species varied considerably in their acidifying ability; proton production ranged from 77 to 136 cmol/kg dry matter. Chickpea and narrow-leafed lupin had the largest acidification potential and field pea the least. The specific acidification (amount of protons produced per kg dry matter) was best correlated with concentrations of excess cations, ash alkalinity, and calcium in plant across the species but was not correlated with plant nitrogen concentration. Total ash alkalinity or total excess cations in shoots provided a good indicator for estimation of total proton production in these species, which were reliant on N2fixation for their source of N. The results have implications for the selection of legumes to be used in sustainable farming systems.

A comparison of proton excretion of twelve pasture legumes grown in nutrient solution

Summary.The use of legumes to improve the productivity of pastures has usually been associated with an increase in soil acidification. The present study compared the acidification potential of 12 N2-fixing pasture legume species/genotypes using a solution culture assay. The legumes were chosen because of their use or potential use in farming systems in the mediterranean zones of southern Australia. The species grown were Trifolium subterraneum L. (vars. Dalkeith, Yarloop and Clare), Trifolium glomeratum L., Trifolium tomentosum L., Medicago murex Willd., Medicago polymorpha L., Medicago truncatulaGaertn., Ornithopus compressus L., Ornithopus sativusBrot., Trifolium vesiculosum and Trifolium balansae. Proton excretion was measured over a period of 21 days from days 40 to 61 after germination. The amount of protons excreted into solution varied between 143 and 265 cmol H+ /kg dry matter for the different species and genotypes. In general, T. tomentosum and T. glomeratum excreted greater amounts of protons per unit biomass than Medicago species and T. subterraneum, which, in turn, excreted more protons than Ornithopus species. The amount of proton excreted per kilogram biomass was well correlated with the concentrations of excess cations over anions and ash alkalinity in plants across all the species. Total acid production was highly correlated with accumulation of excess cations and ash alkalinity, total dry matter production and total nitrogen fixation during the study period. It is suggested that the potential proton excretion by new pasture legume species should be considered when they are introduced into farming systems.

Empirical ferric iron corrections: necessity, assumptions, and effects on selected geothermobarometers

The ferromagnesian silicate minerals, such as garnets, pyroxenes, micas, and amphiboles, appear in a variety of geothermometers and geobarometers. Where complete chemical analyses are available and regardless of bulk composition (metamorphosed pelitic or mafic), the aforementioned minerals commonly contain ferric iron. In mineral analyses using the electron microprobe, ferric and ferrous iron are not distinguished, and all the iron is treated as FeO. In ferric Fe-bearing minerals, this treatment results in (1) low analytical sums and (2) excess cations in the mineral formulae. Assuming ideal stoichiometry (ideal formula cations and oxygens) allows direct ferric estimates in garnets and pyroxenes; amphiboles require additional assumptions concerning site occupancies, and, for micas, no acceptable constraint exists for a ferric estimate. Based on ferric iron determinations for some metamorphic ferromagnesian silicates, the proportion of ferric to total iron increases at higher XMg values. The influence of ferric estimates on T and P calculations depends on the model used and on the extent the ferric estimate alters the relative proportions of end-members. Several examples suggest that, in general, if ferric estimates (or determinations) are made, they should be made for all the relevant minerals.

Ash alkalinity of animal and plant products

The export of farm produce from farming systems results in the removal of excess cations over anions from the soil. This removal of bases from the soil will eventually cause an increase in the acidity of the soil. Ash alkalinity data for a range of farm products are presented in this paper and lime replacement values calculated. Of produce from mixed farming enterprises in north-eastern Victoria, hay required the greatest amount of lime (270-1260 kg CaCO3/ha.year) to replace lost alkali from the soil. By comparison, removal of cereal produce required much less lime (7-20 kg CaCO3/ha.year) to replace lost alkali, as did removal of wool and lamb (0.8 and 6.0 kg CaCO3/ha.year respectively). Management strategies that include a lime replacement value for exported farm produce should be considered in overall farm management strategies to reduce soil acidification.