Optimizing the design of nanostructures for improved thermal conduction within confined spaces

Maintaining constant temperature is of particular importance to the normal operation of electronic devices. Aiming at the question, this paper proposes an optimum design of nanostructures made of high thermal conductive nanomaterials to provide outstanding heat dissipation from the confined interior (possibly nanosized) to the micro-spaces of electronic devices. The design incorporates a carbon nanocone for conducting heat from the interior to the exterior of a miniature electronic device, with the optimum diameter, D0, of the nanocone satisfying the relationship: D02(x) ∝ x1/2 where x is the position along the length direction of the carbon nanocone. Branched structure made of single-walled carbon nanotubes (CNTs) are shown to be particularly suitable for the purpose. It was found that the total thermal resistance of a branched structure reaches a minimum when the diameter ratio, β* satisfies the relationship: β* = γ-0.25bN-1/k*, where γ is ratio of length, b = 0.3 to approximately 0.4 on the single-walled CNTs, b = 0.6 to approximately 0.8 on the multiwalled CNTs, k* = 2 and N is the bifurcation number (N = 2, 3, 4 ...). The findings of this research provide a blueprint in designing miniaturized electronic devices with outstanding heat dissipation

Impact of thermal processing on dietary flavonoids

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGFlavonoids are widely distributed in natural products and foods as a class of polyphenols. They processed diverse bioactivities, including anti-inflammation activity, antiaging activity, and antioxidant activity. The foods rich in flavonoids are usually consumed after thermal processing. However, flavonoids are commonly vulnerable under thermal processing, and it could cause various influences on their stability and bioactivities. Therefore, in this review, the effects of thermal processing on thermal stability and bioactivities of dietary flavonoids from different food sources were first summarized. The strategies to improve thermal stability of dietary flavonoids were then discussed. Noticeably, the effect of some of the promising thermal technologies on dietary flavonoids was also clarified preliminarily in the current review. The promising thermal technologies may be an alternative to conventional thermal processing technologies.Agencia Estatal de Investigación | Ref. RYC2020-030365-

Effects on Physicochemical and Dissolution Characteristics of Lentinus edodes Stem Powder by Jet Milling

In order to increase the utilization rate of shiitake mushroom by-products, the shiitake mushroom stem was crushed after superfine grinding with a jet mill, with coarse powder and 40 mesh powder as the control. The effect of jet milling on the physicochemical properties of shiitake mushroom stem powder and the dissolution amount of functional components represented by ergosterol and polysaccharides were studied. The cumulative dissolution rate of ergosterol and polysaccharides was fitted by the Weibull model. The results showed that after superfine grinding by jet milling, the average particle size (D50) of powder decreased to 3.21 μm, bulk density, tap density and L* value increased from 0.15 g/mL to 0.25 g/mL, 0.23 g/mL to 0.42 g/mL, 65.31 to 73.49, respectively. The superfine powder fluidity, water holding capacity and swelling capacity were significantly enhanced (P<0.05). The cumulative dissolution 50% of the time (T50) of ergosterol and polysaccharide in superfine powder was reduced by 2.56 min and 8.14 min, respectively, compared with coarse powder. And cumulative dissolution rate at 45 min (Q45) increased by 10.88% and 19.15%, respectively. The powder properties and the dissolution rate of the functional ingredients were improved, after the jet milling to treat the shiitake mushroom stem, which was conducive to the comprehensive utilization of shiitake mushroom by-products

Antifungal Activity and Mechanism of Perillaldehyde against Penicillium citrinum, a Major Fungal Pathogen of Myrica rubra

Perillaldehyde is a green and safe natural antibacterial substance extracted from perilla leaves, which is also used as a food additive in food production. In this study, the inhibitory effect of perillaldehyde on Penicillium citrinum, a major pathogen of Chinese bayberry (Myrica rubra), was investigated by minimum inhibitory concentration (MIC), spore germination rate and mycelial growth inhibition assays, and the underlying mechanism was elucidated by studying the mycelial morphology and ultrastructure, cell membrane damage, membrane lipid peroxidation and changes in functional groups. The results showed that the MIC of perillaldehyde on P. citrinum was 120 μL/L. Mycelial growth was completely inhibited by treatment with 120 μL/L perillaldehyde, and the relative conductivity and malondialdehyde (MDA) content increased. Compared with the untreated group, ergosterol, total lipid and chitin contents and mitochondrial adenosine triphosphatase (ATPase) activity decreased by 80.00%, 81.25%, 64.97% and 87.40% in P. citrinum treated with 90 μL/L perillaldehyde. The treatment with perillaldehyde damaged cell membrane permeability and affected the normal physiological function of the cell membrane. By scanning electron microscopy (SEM) and transmission electron microscopy (TEM), it was found showed that the broom-like conidial head of P. citrinum disappeared after perillaldehyde treatment, and the mycelia appeared to be broken and ablated. Moreover, the cell membrane was broken, intracellular contents leaked out, and the cells became shriveled. In addition, the amounts of leakage of soluble protein, soluble sugar and nucleic acid from P. citrinum treated with 120 μL/L perillaldehyde for 5 h increased by 71.20%, 210.93% and 117.31% compared with those before the treatment, which verified cell membrane damage. By using Fourier transform infrared (FTIR) spectroscopy, it was found that the contents of functional groups such as hydroxyl, methyl, aromatic carbon skeleton and benzene ring carbon skeleton in perillaldehyde treated P. citrinum decreased, and internal substances were gradually consumed. In summary, perillaldehyde showed a good antifungal activity on P. citrinum by destroying cell membrane structure, changing membrane permeability, interfering with energy metabolism and destroying protein and genetic material. Perillaldehyde has good research and development prospects as a natural preservative

Optimization of Preparation Process of Bayberry Soft Candy and Analysis of Its Hypoglycemic Function

In order to develop soft fruit candy products with hypoglycemic function, the preparation method was optimized by single-factor and response surface studies. The texture profile analysis and sensory score was regarded as the evaluation indices, while bayberry juice was used as the main raw material, carrageenan and gelatin as the gelling agent, and xylitol as the sweetener. Additionally, the hypoglycemic effect of bayberry soft candy extract was evaluated by in vitro study, and the components of bayberry juice was detected by using UPLC-MS/MS assay. Finally, the hypoglycemic components and related pathways of action were predicted by network pharmacology. The results showed that in the 100 mL bayberry soft candy gel solution system, the optimal formulation of bayberry soft candy obtained by response surface methodology was as follows: 89.37% bayberry juice for swelling and constant volume, with 9.90% gelatin, 1.41% carrageenan, and 30.86% xylitol addition. The sensory score of bayberry soft candy produced under this process was 87.30, which was close to the theoretical value. The in vitro hypoglycemic study showed that the inhibition of α-glucosidase and α-amylase by 4 mg/mL of bayberry soft candy extract reached 98.58% and 86.89%, respectively. The network pharmacological analysis postulated that 3,5-diacetyltambrin (YM16), azaleatin (YM17) and raspberry ketone glucoside (YM1) were the key hypoglycemic components in bayberry juice, in addition, the human cancer pathway and PI3K-Akt pathway were important pathways of their action. The soft candy prepared under the optimal process condition showed good elasticity, fantastic taste and certain hypoglycemic effects. These results provide a certain theoretical basis for the development of fruit-flavored functional soft candy

Effect of Fermentation on Volatile Flavor Compounds in Blue Honeysuckle-Blueberry Juice Mixture Based on Gas Chromatography-Ion Mobility Spectrometry

In the study, gas chromatography-ion mobility spectrometry (GC-IMS) coupled with electronic nose and sensory evaluation was used to analyze the change of volatile compounds in blue honeysuckle-blueberry juice mixture during fermentation, and key aroma compounds were identified by the combined use of orthogonal partial least squares discriminant analysis (OPLS-DA) and odor activity values (OAV). Meanwhile, the changes in nutritional quality were analyzed by measuring physicochemical properties, active compounds and antioxidant capacity. The results showed that the flavor of blue honeysuckle-blueberry juice mixture was significantly enhanced after fermentation for 24 hours, and the fruity aroma, fermented aroma and aftertaste were enriched. A total of 58 volatile compounds were identified by GC-IMS, including esters, aldehydes, alcohols, ketones and furans. After fermentation, the contents of various flavor compounds such as esters (e.g., methyl propionate and ethyl butyrate) and alcohols (e.g., isoamyl alcohol and n-hexanol) significantly increased, synergistically contributing to a blend of fruity, floral and fermented aromas. Additionally, fermentation led to a reduction in the contents of aldehydes and sulfides, thereby weakening the grassy and pungent odors and consequently resulting in a more harmonious flavor profile. The OPLS-DA and OAV analyses identified butyl acrylate, ethyl hexanoate, isoamyl acetate, ethyl butyrate, ethyl valerate, 2-formylpyrrole, 3-hepten-2-one, and isopentyl alcohol as differential characteristics flavor compounds after fermentation. The juice turned from black-purple to brighter red-purple, while the contents of active compounds such as polyphenols, ascorbic acid, and antioxidant levels were maintained at a high level. The juice maintained good quality, and the flavor was significantly enhanced after yeast fermentation for 24 hours. This study confirms that co-fermentation of two fruits can break through the limitation of a single raw material, providing a theoretical basis for the development of functional fermented fruit juice with good nutrition and flavor and being of practical significance for innovation in deep-processing technology and high-value utilization of resources