Turbo space-time coding for mimo systems : designs and analyses

Multiple input multiple output (MIMO) systems can provide high diversity, high data rate or a mix of both, for wireless communications. This dissertation combines both modes and suggests analyses and techniques that advance the state of the art of MIMO systems. Specifically, this dissertation studies turbo space-time coding schemes for MIMO systems. Before the designs of turbo space-time codes are presented, a fundamental tool to analyze and design turbo coding schemes, the extrinsic information transfer (EXIT) chart method, is extended from the binary/nonbinary code case to coded modulation case. This extension prepares the convergence analysis for turbo space-time code. Turbo space-time codes with symbols precoded by randomly chosen unitary time variant linear transformations (TVLT) are investigated in this dissertation. It is shown that turbo codes with TVLT achieve full diversity gain and good coding gain with high probability. The probability that these design goals are not met is shown to vanish exponentially with the Hamming distance between codewords (number of different columns). Hence, exhaustive tests of the rank and the determinant criterion are not required. As an additional benefit of the application of TVLT, with the removal of the constant modulation condition, it is proved that throughput rates achieved by these codes are significantly higher than the rates achievable by conventional space-time codes. Finally, an EXIT chart analysis for turbo space-time codes with TVLT is developed, with application to predicting frame error rate (FER) performance without running full simulation. To increase the data rate of turbo-STC without exponentially increasing the decoding complexity, a multilevel turbo space-time coding scheme with TVLT is proposed. An iterative joint demapping and decoding receiver algorithm is also proposed. For MIMO systems with a large number of transmit antennas, two types of layered turbo space-time (LTST) coding schemes are studied. For systems with low order modulation, a type of LTST with a vertical encoding structure and a low complexity parallel interference cancellation (PlC) receiver is shown to achieve close to capacity performance. For high order modulation, another type of LTST with a horizontal encoding structure, TVLT, and an ordered successive interference cancellation (OSIC) receiver is shown to achieve better performance than conventional layered space-time coding schemes, where ordering is not available in the SIC detection

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 of Perfluorooctanoic Acid on the Associated Genes Expression of Autophagy Signaling Pathway of Carassius auratus Lymphocytes in vitro

Perfluorooctanoic acid (PFOA) has been detected in various water bodies and caused harm to aquatic organisms. The aim of this study was to investigate the cytotoxicity and mechanism associated with autophagy and oxidative stress after exposure to PFOA (0, 1, 10, 100 μg/L) for 12 h on lymphocytes, which was isolated from the head kidney of Carassius auratus (C. auratus). Both of autophagy formation, cell activity, and intracellular reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) levels were measured. The relative expression of partial autophagy-related genes autophagy related 5 (Atg 5), autophagy related 7 (Atg 7), and Beclin 1 were also cloned and detected. Homologous relationships analysis showed high identities of genes in C. auratus and other fish by blast. C. auratus lymphocytes growth inhibition rates was increased induced by PFOA. Compared with the control group, the ROS generation and the MDA content were significantly increased in all of the PFOA-treated group. Besides, decreased SOD activity and decrease of GSH activity induced by PFOA further confirmed the occurrence of oxidative stress. The number of autophagosome formations was increased in a dose-dependent manner. Compared with the control group, Atg 7 and Beclin 1 mRNA expression was elevated significantly after PFOA exposed, showing a time-dependent manner, while mRNA expression of Atg 5 was increased remarkably in 100 μg/L PFOA-treated group. Our results indicated that PFOA caused oxidative damage to lymphocytes in C. auratus and caused various autophagy signaling pathway-associated genes imbalances in the lymphocytes. Autophagy signaling pathway-associated genes imbalance could weaken antioxidant capacity and involve in the mechanism of C. auratus lymphocytes oxidative injury caused by PFOA

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

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