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.

Artificial intelligence in food science and nutrition: a narrative review.

In the late 2010s, artificial intelligence (AI) technologies became complementary to the research areas of food science and nutrition. This review aims to summarize these technological advances by systematically describing the following: the use of AI in other fields (eg, engineering, pharmacy, and medicine); the history of AI in relation to food science and nutrition; the AI technologies currently used in the agricultural and food industries; and some of the important applications of AI in areas such as immunity-boosting foods, dietary assessment, gut microbiome profile analysis, and toxicity prediction of food ingredients. These applications are likely to be in great demand in the near future. This review can provide a starting point for brainstorming and for generating new AI applications in food science and nutrition that have yet to be imagined.

Coffee bean polyphenols ameliorate postprandial endothelial dysfunction in healthy male adults.

To reveal the effect of coffee bean polyphenols (CBPs) on blood vessels, this study aimed to investigate the effect of CBPs on acute postprandial endothelial dysfunction. Thirteen healthy non-diabetic men (mean age, 44.9 ± 1.4 years) consumed a test beverage (active: containing CBPs, placebo: no CBPs) before a 554-kcal test meal containing 14 g of protein, 30 g of fat and 58 g of carbohydrates. Then, a crossover analysis was performed to investigate the time-dependent changes in flow-mediated dilation (FMD) in the brachial artery. In the active group, the postprandial impairment of FMD was significantly improved, the two-hour postprandial nitric oxide metabolite levels were significantly increased and the six-hour postprandial urinary 8-epi-prostaglandin F2α levels were significantly reduced compared to the placebo group. The test meal increased the levels of blood glucose, insulin and triglycerides in both groups with no significant intergroup differences. These findings indicate that CBPs intake ameliorates postprandial endothelial dysfunction in healthy men.

Origin of an isothermal R-martensite formation in Ni-rich Ti-Ni solid solution: crystallization of strain glass.

We report that R martensite isothermally forms with time in a solution-treated Ti(48.7)Ni(51.3) single crystal. This abnormal formation originates from the growth of a short-range ordered R phase with time, i.e., the "crystallization" of strain glass. The established time-composition-temperature Ti-Ni diagram shows a time evolution of the R phase and composition-temperature phase diagram. The presence or absence of the R phase in this new diagram, as well as in other conditions (like doping Fe or aging), is explained in a unified framework of free-energy landscape. Our finding suggests a new mechanism for the isothermal martensite formation, which could be applied to other metal and ceramic martensitic systems to find new phases and novel properties.

Direct evidence for local symmetry breaking during a strain glass transition.

Strain glass transition is a unique nanoscale displacive transition with local symmetry breaking while maintaining the macroscopic symmetry or average structure unchanged. It usually occurs in the "nonmartensitic" composition range of a martensitic system. So far, only indirect evidence exists for such a transition, essentially from macroscopic measurements and low-resolution transmission electron microscopy observations, and there is a lack of direct evidence for the speculated local symmetry breaking and the sluggish nature of the glass transition. In this Letter we report in situ high-resolution transmission electron microscopy observations on a Ti50(Pd41Cr9) strain glass alloy and direct evidence for these key issues. Our results show that at temperatures well above the strain glass transition temperature (Tg), the lattice is essentially an undistorted B2 structure. With approaching Tg, the local symmetry breaking gradually occurs with the formation and growth of nanomartensite clusters with a combined stacking period of three and four plane intervals, but the average structure measured by x-ray diffraction remains B2. These nanomartensite clusters become finally frozen below Tg. Our results provide not only a microscopic basis for the macroscopic properties of strain glass, but also new insights into a range of possible applications of this unique class of materials.

Coffee polyphenols improve peripheral endothelial function after glucose loading in healthy male adults.

Brewed coffee is a widely consumed beverage, and many studies have examined its effects on human health. We investigated the vascular effects of coffee polyphenols (CPPs), hypothesizing that a single ingestion of CPP during glucose loading would improve endothelial function. To test this hypothesis, we conducted a randomized acute clinical intervention study with crossover design and measured reactive hyperemia index (RHI) to assess the acute effects of a 75-g glucose load with CPP in healthy, nondiabetic adult men. Blood glucose and insulin levels were elevated after glucose loading with and without CPP, with no significant differences between treatments. The RHI did not significantly decrease after glucose loading without CPP. With CPP, however, RHI significantly (P < .05) increased over baseline after glucose loading. The difference between treatments was statistically significant (P < .05). No significant changes were observed in an oxidative stress marker after glucose loading with or without CPP. These findings suggest that a single ingestion of CPP improves peripheral endothelial function after glucose loading in healthy subjects.

Nonhysteretic superelasticity of shape memory alloys at the nanoscale.

We perform molecular dynamics simulations to show that shape memory alloy nanoparticles below the critical size not only demonstrate superelasticity but also exhibit features such as absence of hysteresis, continuous nonlinear elastic distortion, and high blocking force. Atomic level investigations show that this nonhysteretic superelasticity results from a continuous transformation from the parent phase to martensite under external stress. This aspect of shape memory alloys is attributed to a surface effect; i.e., the surface locally retards the formation of martensite and then induces a critical-end-point-like behavior when the system is below the critical size. Our work potentially broadens the application of shape memory alloys to the nanoscale. It also suggests a method to achieve nonhysteretic superelasticity in conventional bulk shape memory alloys.

Impact of the volume change on the ageing effects in Cu-Al-Ni martensite: experiment and theory.

The time evolution of the physical properties of martensite during martensite ageing is traditionally explained by the symmetry-conforming short-range order (SC-SRO) principle, which requires the spatial configuration of crystal defects to follow the symmetry change of the host lattice. In the present study, we show that the volume change of the host lattice also contributes to the ageing effects in Cu-Al-Ni shape memory alloy besides the symmetry change. To substantiate this statement the gradual increase of the storage modulus with time at constant temperature was measured by dynamic mechanical analysis (DMA) and the experimental results were quantitatively described in the framework of the symmetry-conforming Landau theory of martensitic transformations in a crystal with defects. The comparison of experimental and theoretical results confirmed that the time dependence of the storage modulus is caused by two different physical mechanisms. Evaluations showing that the first mechanism is driven by the spontaneous symmetry change and the second mechanism is caused by the volume change after the martensitic transformation was carried out.

A catechin-rich beverage improves obesity and blood glucose control in patients with type 2 diabetes.

We investigated the effects of continuous ingestion of a catechin-rich beverage in patients with type 2 diabetes who were not receiving insulin (Ins) therapy in a double-blind controlled study. The participants ingested green tea containing either 582.8 mg of catechins (catechin group; n = 23) or 96.3 mg of catechins (control group; n = 20) per day for 12 weeks. At week 12, the decrease in waist circumference was significantly greater in the catechin group than in the control group. Adiponectin, which is negatively correlated with visceral adiposity, increased significantly only in the catechin group. Although the increase in Ins at week 12 was significantly greater in the catechin group than in the control group, no apparent difference was noted between the two groups in glucose and hemoglobin A(1c). In patients treated with insulinotropic agents, the increase in Ins at week 12 was significantly greater in the catechin group than in the control group. This significant increase in Ins levels was observed only in the catechin group. In the catechin group receiving other treatments, Ins levels remained unchanged. In addition, in patients treated with insulinotropic agents, the decrease in hemoglobin A(1c) at week 12 was significantly greater in the catechin group than in the control group. These results suggest that a catechin-rich beverage might have several therapeutic uses: in the prevention of obesity; in the recovery of Ins-secretory ability; and, as a way to maintain low hemoglobin A(1c) levels in type 2 diabetic patients who do not yet require Ins therapy.

Shape memory effect and superelasticity in a strain glass alloy.

The shape memory effect and superelasticity are usually found in alloys exhibiting spontaneous martensitic transformation. Thus it is hard to imagine that such interesting effects can appear in a system without a martensitic transformation. In this Letter we show shape memory and the superelasticity effect in a nonmartensitic Ti48.5Ni51.5 alloy, which has no martensitic transformation but undergoes a "strain glass" transition. In situ x-ray diffraction experiment showed that the shape memory and superelasticity in strain glass stem from a stress-induced strain glass to martensite transformation and its reverse transformation. The new shape memory and superelasticity in strain glass extends the regime of the shape memory effect and superelasticity and may lead to novel applications.

Evidence for strain glass in the ferroelastic-martensitic system Ti(50-x)Ni(50+x).

We report here "strain glass," a new glassy phenomenon in ferroelastic-martensitic system of Ni-rich intermetallic Ti(50-x)Ni(50+x) (x > 1), where local strain is frozen in disordered configuration below a critical temperature Tg. The ac elastic modulus shows a minimum at Tg, which exhibits logarithmic frequency dependence following Vogel-Fulcher relationship, and the corresponding internal friction shows a frequency-dependent peak located at a lower temperature. In situ high-resolution transmission electron microscopy observations reveal uncorrelated nanoclusters of martensiticlike phase, randomly frozen in the otherwise untransformed parentlike matrix. Being parallel to spin glass and relaxor, strain glass may shed new light on the fundamental physics of glass and lead to the discovery of novel properties.