A lightweight strain glass alloy showing nearly temperature-independent low modulus and high strength.

Fast development of space technologies poses a strong challenge for elastic materials, which need to be not only lightweight, strong and compliant, but also able to maintain stable elasticity over a wide temperature range1-4. Here we report a lightweight magnesium-scandium strain glass alloy (Mg with 21.3 at.% Sc) that meets this challenge. This alloy is as light (density ~2 g cm-3) and compliant as organic-based materials5-7 like bones and glass fibre reinforced plastics, but in contrast with those materials, it possesses a nearly temperature-independent (or Elinvar-type), ultralow Young's modulus (~20-23 GPa) over a wide temperature range from room temperature down to 123 K; a higher yield strength of ~200-270 MPa; and a long fatigue life of over one million cycles. As a result, it exhibits a relatively high, temperature-independent elastic energy density of ~0.5 kJ kg-1 among known materials at a moderate stress level of 200 MPa. We show that its exceptional properties stem from a strain glass transition, and the Elinvar-type elasticity originates from its moderate elastic softening effect cancelling out the ever-present elastic hardening. Our findings provide insight into designing materials that possess unconventional and technologically important elastic properties.

Phosphate Starvation by Energy Metabolism Disturbance in Candida albicansvip1Δ/Δ Induces Lipid Droplet Accumulation and Cell Membrane Damage.

Phosphorus in the form of phosphate (Pi) is an essential element for metabolic processes, including lipid metabolism. In yeast, the inositol polyphosphate kinase vip1 mediated synthesis of inositol heptakisphosphate (IP7) regulates the phosphate-responsive (PHO) signaling pathway, which plays an important role in response to Pi stress. The role of vip1 in Pi stress and lipid metabolism of Candida albicans has not yet been studied. We found that when vip1Δ/Δ was grown in glucose medium, if Pi was supplemented in the medium or mitochondrial Pi transporter was overexpressed in the strain, the lipid droplet (LD) content was reduced and membrane damage was alleviated. However, further studies showed that neither the addition of Pi nor the overexpression of the Pi transporter affected the energy balance of vip1Δ/Δ. In addition, the LD content of vip1Δ/Δ grown in Pi limitation medium PNMC was lower than that grown in SC, and the metabolic activity of vip1Δ/Δ grown in PNMC was also lower than that grown in SC medium. This suggests that the increase in Pi demand by a high energy metabolic rate is the cause of LD accumulation in vip1Δ/Δ. In addition, in the vip1Δ/Δ strains, the core transcription factor PHO4 in the PHO pathway was transported to the vacuole and degraded, which reduced the pathway activity. However, this does not mean that knocking out vip1 completely blocks the activation of the PHO pathway, because the LD content of vip1Δ/Δ grown in the medium with ß-glycerol phosphate as the Pi source was significantly reduced. In summary, the increased Pi demand and the decreased PHO pathway activity in vip1Δ/Δ ultimately lead to LD accumulation and cell membrane damage.

Preparative separation of six compounds from Salvia yunnanensis Radix using pH-zone-refining counter-current chromatography.

Phenolic acids are the main active components in Salvia yunnanensis Radix, which have significant effects such as cardiovascular protection, anti-thrombosis, anti-oxidant, and anti-inflammation. In this study, pH-zone-refining counter-current chromatography (pH-ZRCCC) was successfully applied to the preparative separation of phenolic acids from S. yunnanensis Radix. First, a two-phase solvent system composed of Pet-EtOAc-ACN-H2 O (1.5:2.5:1:5, v/v) [TFA (10 mM) was added in the upper phase and NH3 ·H2 O (30 mM) was added in the lower phase] was used for the separation of 4.0 g of the crude sample to obtain 55.6 mg of rosmarinic acid (1), 69.0 mg of caffeic acid (2), 18.9 mg of protocatechualdehyde (3), 14.6 mg of 8-epiblechnic acid 9-methyl ester (4), and a mixture containing two compounds. After the recovery, 1.3 g of the mixture was obtained and separated using the MtBE-H2 O (1:1, v/v) solvent system containing TFA (5 mM) and NH3 ·H2 O (60 mM) to obtain 259.9 mg of salvianolic acid B (5) and 28.75 mg of lithospermic acid (6). Moreover, a systematic separation pattern for separating the relatively low-polarity phenolic acids from natural products by pH-ZRCCC was summarized for the first time. This study provided technical support for the pharmacological activity and quality control research of S. yunnanensis Radix.

Preparative separation of seven polyphenols from Perillae Folium via pH-zone-refining counter-current chromatography combined with high-speed counter-current chromatography.

Perillae Folium is a well-known traditional Chinese medicine, and it possesses anti-inflammatory, anti-oxidant, and hypolipidemic effects. The pharmacological properties of Perillae Folium are based on its main functional compositions, such as phenolic acids, flavonoids, and volatile oils. In this study, seven polyphenols, including three phenolic acids and four flavonoid glycosides, were successfully isolated from Perillae Folium by pH-zone-refining counter-current chromatography (pH-ZRCCC) combined with traditional high-speed counter-current chromatography (HSCCC). First, the crude sample was separated by pH-ZRCCC using a biphasic solvent system composed of pet ether-ethyl acetate-acetonitrile-water (1 : 3 : 1 : 5, v/v). The upper phase of the biphasic solvent system added trifluoroacetic acid (10 mM) as the stationary phase, and the lower phase added ammonia water (30 mM) as the mobile phase. In this separation, one compound, rosemary acid (I), with high purity and a mixture were obtained. The mixture was further separated using HSCCC with a ethyl acetate-n-butanol-water (4.8 : 0.2 : 5, v/v) solvent system to obtain apigenin-7-O-[ß-d-glucuronopyranosyl (1→2)-O-ß-d-glucuronopyranoside] (II), luteolin-7-O-ß-d-glucuronide (III), 4-hydroxycinnamic acid (IV), scutellarin (V), caffeic acid (VI), and apigenin-7-O-ß-d-glucuronide (VII). The purities of the obtained compounds were above 92.7%. The study demonstrated that the combination of pH-ZRCCC and HSCCC is an effective method for the preparation and separation of polyphenols, particularly the complex mixture of phenolic acids and flavonoids from natural products.

Purification of pyrethrins from flowers of Chrysanthemum cineraraeflium by high-speed counter-current chromatography based on coordination reaction with silver nitrate.

Pyrethrum extract is a natural insecticide that has been used worldwide for centuries, with pyrethrins being considered active ingredients. Their purification is difficult due to their chemical structural similarity and instability to light. In the present study, a coordination complex high-speed counter-current chromatography was used to separate pyrethrins from pyrethrum extract. The two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water (10:2:10:2, v/v/v/v) with 0.30 mol/L silver nitrate was selected for separation. As a result, five pyrethrins including cinerin II (31.2 mg), pyrethrin II (43.9 mg), jasmalin II (39.1 mg), pyrethrin I (32.4 mg), and jasmalin I (16.0 mg) were obtained from 400 mg crude extract in 6 h by one-step HSCCC separation, with purities over 95%. The isolated compounds were identified by MS, 1H-NMR and 13C-NMR spectroscopy. The results demonstrated that the addition of silver nitrate in the two-phase solvent system of HSCCC significantly increased the HSCCC separation factor of pyrethrins. HSCCC is a rapid method for purification of pyrenthrins from pyrethrum extract. The established method may also be applied to separate analogous compounds from natural products in which the chemical structure differs in the position or numbers of alkenes.

Preparative separation of caffeoylquinic acid isomers from Lonicerae japonicae Flos by pH-zone-refining counter-current chromatography and a strategy for selection of solvent systems with high sample loading capacities.

Caffeoylquinic acid derivatives exhibit anti-inflammatory, antioxidant, and antibacterial activities. We successfully applied pH-zone-refining counter-current chromatography (pH-ZRCCC) to separation of isomeric caffeoylquinic acids from Lonicerae japonicae Flos using a two-phase solvent system composed of ethyl acetate-n-butanol-acetonitrile-water (3:1:1:5, v/v/v/v). Trifluoroacetic acid (10 mM) was added to the upper phase as a retainer and ammonium hydroxide (10 mM) was added to the lower phase as an eluter. As a result, 167.8 mg of chlorogenic acid, 15.9 mg of isochlorogenic acid B, 103.4 mg of isochlorogenic acid C, and 156.0 mg of isochlorogenic acid A were obtained from 1.2 g of crude extract, and all compound purities were over 96%. In addition, by comparing the numeric values of partition coefficient of compounds, it was found that larger differences between the K values of adjacent compounds in the solvent systems resulted in higher sample loading capacities. pH-ZRCCC method is an efficient preparative separation of isomeric caffeoylquinic acids from natural products.

[Advance in studies on Aconitum traditional Chinese medicines in toxicokinetics and metabonomics].

Aconitum, as a kind of common traditional Chinese medicine, contains multiple biological active substances, with a very high medicinal value but high toxicity. Its major toxic ingredients are aconitine, mesaconitine and hypaconitine, which are also efficient ingredients. Therefore, the safety of its clinical application has aroused wide attention. With the constant deepening of drug development studies, people want to learn about its toxic mechanism and the regularity of its emergence and development of its toxicology, so as to make a scientific and rational assessment for its safety. Therefore, toxicokinetics and metabonomics have gradually become important content in the new drug assessment. During the development of drug performance, it is crucial to establish a scientific, objective and standardized Aconitum safety evaluation system and correctly assess and utilize its toxicity. Having summarized studies on metabonomics and toxicokinetics of Aconitum drugs in recent years, authors proposed to strengthen the studies on Aconitum drug safety assessment and establish a scientific and standardized safety evaluation system as soon as possible, in order to make the national treasure more useful.