Evolution of Ferroelectricity in Sr0.6Ba0.4Nb2O6-BaTiO3 Solid Solution with a Strong Electrocaloric Effect.

In conventional knowledge, ferroelectric solid solutions were formed between members belonging to the same crystal structure family. Since both tungsten bronze and perovskite structures are constructed by connecting the corner-sharing oxygen octahedra, it offers a possibility for formatting an unusual solid solution between these two families. Herein, (1 - x)Sr0.6Ba0.4Nb2O6-xBaTiO3, (1 - x)SBN-xBT, solid solutions were synthesized and the solution mechanism was resolved from a structure viewpoint. With increasing BT content, the solid solution persists of tetragonal tungsten bronze structure, but the lattice parameter a (= b) decreases whereas c increases, resulting in the significant reduction of grains anisotropy. The ferroelectric-relaxor phase transition temperature shows a monotonic increase as x increases. However, the ferroelectricity evolution is not monotonous as a function of BT content because of the competitive effects of Ba and Ti on the property. As a result, the x = 0.10 ceramic shows the strongest ferroelectricity and a remarkable electrocaloric effect of 1.4 K near room temperature. This work challenges the traditional view of solid solution formation and provides an alternative way to modulate the structure and properties of ferroelectrics.

A study on the catalytic domain of pork phospholipase A2: Enzymatic properties and hydrolysis characteristics of phosphatidylcholine and its hydroperoxide.

Endogenous phospholipase A2 (PLA2) plays an important role in phospholipids degradation during cured meat products manufacturing. The present study was undertaken to reveal more information about the endogenous PLA2 in muscles and its role in degradation of intramuscular phospholipids. With the catalytic domain of pork calcium-independent PLA2 (iPLA2cd), impacts of physic-chemical factors on the activity were investigated and substrate specificity of the enzyme were tested respectively. The optimum temperature and pH of pork iPLA2cd were 40 °C and 7.5, respectively. The iPLA2cd could be stimulated by adequate contents of NaCl and ATP, and inhibited by CaCl2 and NaNO2. For native phospholipids, the iPLA2cd was of a little higher affinity towards phosphatidylcholine (PC) than phosphatidylethanolamine (PE), phosphoserine (PS) and phosphatidylinositol (PI). The iPLA2cd could preferentially hydrolyze peroxidized PC over the native PC. The results would help better understand the degradation of phospholipids and the role played by endogenous enzymes during meat products manufacturing.

Mapping of Long-Wavelength Phonon Contribution in the Thermal Transport of Alloyed Semiconductor Superlattices.

The mapping of long-wavelength phonons is important to understand and manipulate the thermal transport in multilayered structures, but it remains a long-standing challenge due to the collective behaviors of phonons. In this study, an experimental demonstration of mapping the long-wavelength phonons in an alloyed Al0.1Ga0.9As/Al0.9Ga0.1As superlattice system is reported. Multiple strategies to filter out the short- to mid-wavelength phonons are used. The phonon mean-free-path-dependent thermal transport properties directly demonstrate both the suppression effect of the ErAs nanoislands and the contribution of long-wavelength phonons. The contribution from phonons with mean free path longer than 1 µm is clearly demonstrated. A model based on the Boltzmann transport equation is proposed to calculate and describe the thermal transport properties, which depicts a clear physical picture of the transport mechanisms. This method can be extended to map different wavelength phonons and become a universal strategy to explore their thermal transport in various application scenarios.

Lipidomics analysis of Sanhuang chicken during cold storage reveals possible molecular mechanism of lipid changes.

Lipidomic profiles changes of the Sanhuang chicken breast meat during cold storage (4 °C) were analyzed using ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS)-based lipidomic analysis. Total lipids content decreased 16.8% after storage. Triacylglycerol (TAG), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) significantly decreased, while lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE) increased. Particularly, there was a trend that TAGs with fatty acids of 16:0 and 18:1, and phospholipids containing 18:1, 18:2 and 20:4 were more likely to be downregulated. The increase in the ratio of lysophospholipids/phospholipids and the degree of lipid oxidation demonstrated oxidation and enzymatic hydrolysis are potentially responsible for the lipid transformation. Moreover, 12 lipid species (P < 0.05, VIP > 1, FC < 0.8 or >1.25) were identified to be associated with the spoilage of meat. Glycerophospholipid metabolism and linoleic acid metabolism were the key metabolic pathways involved in the lipid transformations of chilled chicken.

Recombinant Porcine 12-Lipoxygenase Catalytic Domain: Effect of Inhibitors, Selectivity of Substrates and Specificity of Oxidation Products of Linoleic Acid.

Lipoxygenase (LOX) is a major endogenous enzyme for the enzymatic oxidation of lipids during meat storage and meat product manufacturing. In the present work, some characteristics, i.e., effects of inhibitors, selectivity of substrates and specificity of oxidation products, were studied using recombinant porcine 12-lipoxygenase catalytic domain (12-LOXcd). Several familiar inhibitors were found inhibit the activity of recombinant porcine 12-LOXcd;nordihydroguaiaretic acid demonstrated the strongest inhibitory effect. The enzyme could oxygenate common polyunsaturated fatty acids, and showed the highest affinity to linoleic acid (LA), followed by arachidonic acid (AA), linolenic acid (LN) and docosahexaenoic acid (DHA). Under the action of porcine 12-LOXcd, LA was oxidized into four hydroxyoctadecadienoic acid (HODE) isomers, i.e., 13-Z,E-HODE, 13-E,E-HODE, 9-Z,E-HODE and 9-E,E-HODE. Variation of pH not only affected the yield of LA oxidation products, but also the distribution of HODE isomers. These results indicated that endogenous LOX activity and LOX-catalyzed lipid oxidation can be regulated during meat storage and meat product manufacturing.

Giant Thermal Transport Tuning at a Metal/Ferroelectric Interface.

Interfacial thermal transport plays a prominent role in the thermal management of nanoscale objects and is of fundamental importance for basic research and nanodevices. At metal/insulator interfaces, a configuration commonly found in electronic devices, heat transport strongly depends upon the effective energy transfer from thermalized electrons in the metal to the phonons in the insulator. However, the mechanism of interfacial electron-phonon coupling and thermal transport at metal/insulator interfaces is not well understood. Here, the observation of a substantial enhancement of the interfacial thermal resistance and the important role of surface charges at the metal/ferroelectric interface in an Al/BiFeO3 membrane are reported. By applying uniaxial strain, the interfacial thermal resistance can be varied substantially (up to an order of magnitude), which is attributed to the renormalized interfacial electron-phonon coupling caused by the charge redistribution at the interface due to the polarization rotation. These results imply that surface charges at a metal/insulator interface can substantially enhance the interfacial electron-phonon-mediated thermal coupling, providing a new route to optimize the thermal transport performance in next-generation nanodevices, power electronics, and thermal logic devices.

Structural and antimicrobial properties of Maillard reaction products in chicken liver protein hydrolysate after sonication.

This study aimed to investigate the structural and antimicrobial properties of Maillard reaction products (MRPs) in chicken liver protein (CLP) and its hydrolysate (CLPH) after sonication (SCLPH). The MRPs of CLP (CLPM), CLPH (CLPHM) and SCLPH (SCLPHM) were analyzed by several spectrometric techniques. The molecular weights of the CLPHM and SCLPHM were primarily between 1.35 kDa and 17 kDa. Moreover, the molecular weights in the CLPHM and SCLPHM below 1.35 kDa were increased, which indicated that cross-linking and thermal degradation occurred during the Maillard reaction (MR). The SCLPHM showed an obvious network skeleton, and the surface had many small crystal-shaped particles after ultrasound treatment and MR by scanning electron microscopy. The SCLPHM had more negative charges than the CLPHM, thus effectively inhibiting the growth of S. saprophyticus and E. coli. MR and ultrasound treatment could be a promising technology to expand the application prospects of low-value meat byproducts.

Novel sample treatment method for the determination of free (E)-4-hydroxy-2-nonenal in meat products by liquid chromatography/tandem mass spectrometry using 4-hydroxy-2-nonenal-d3 as internal standard.

RATIONALE: (E)-4-Hydroxy-2-nonenal (HNE) is a reactive secondary product of lipid oxidation with biological significance. The analysis of HNE is a challenge due to its volatility and high activity. Developing sample preparation and analytical tools for the determination of free HNE is crucial for better understanding the actual level of free HNE in meat products. METHODS: Liquid nitrogen freezing, subzero-temperature extraction and derivatization were employed for meat sample treatment. Liquid chromatography/tandem mass spectrometry with electrospray ionization in negative ion mode was used for the determination of free HNE after isotope-coded derivatization. RESULTS: High repeatability and good recoveries with a limit of quantification as low as 0.25 pmol/g were found. Nineteen out of 24 samples, including chilled/processed meat products and meat-based instant foods, were found to contain free HNE with a range of 0.014-1.160 nmol/g. CONCLUSIONS: The proposed method showed satisfactory reliability, sensitivity and accuracy. We believe that such a sample preparation strategy will provide a powerful tool for better understanding the actual level of free HNE in meat products.

Development of indirect competitive ELISA for determination of dehydroabietic acid in duck skin and comparison with the HPLC method.

Defeathering with rosin results in rosin residue in duck skin, which may present as potential risk to human health. Dehydroabietic acid (DHAA) is a major component of rosin. An indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed for determination of DHAA in duck skin. A set of parameters was optimized, including coating antigen concentration, dilution of antiserum, dilution of HRP-IgG antibody, incubation time, and temperature for antigen reaction with antiserum. The indirect competitive ELISA yielded an excellent specificity against DHAA with low cross-reactivity toward other resin acids. The limit of detection and the working concentration range of DHAA in duck skin were 16.4 ng/g and from 40 to 8,060 ng/g, respectively. The indirect competitive ELISA was applied to the determination of DHAA in duck skin samples spiked with DHAA at different contents, and recoveries were found between 78.2 and 97.2%. Finally, DHAA contents in 32 duck samples were quantified by the indirect competitive ELISA and high performance liquid chromatography-fluorescence detector (HPLC-FLD) method. No significant difference was found between DHAA concentrations from indirect competitive ELISA and HPLC-FLD method for all samples, which indicated the indirect competitive ELISA established in this article was of the same accuracy as the HPLC-FLD method. The indirect competitive ELISA was simple, rapid, and reliable, which could be used to identify the duck carcasses defeathered with rosin in the market.

Chemo-enzymatic synthesis, characterization, in vitro antioxidant capacity and oxidative stability studies of novel phosphatidylcholines with ω-3/ω-6 PUFAs and phenolic acids.

Novel phosphatidylcholines containing PUFAs and phenolic acids were synthesized from egg phosphatidylcholine (PC), PUFAs (docosahexaenoic, arachidonic and linoleic acids) and phenolic acids (caffeic, ferulic and p-coumaric acids) as substrates. The structures of modified PCs were confirmed by spectral analysis and were evaluated for antioxidant activities. The modified PCs containing caffeic and ferulic acids exhibited excellent antioxidant activities compared with butylated hydroxytoluene (BHT) and α-tocopherol. The synthesized compounds were also evaluated for the oxidative stabilities in liposome and organic solvent. The modified PCs showed more oxidative stable compared with standard PUFA-PCs and PUFA-PCs + BHT. Results showed that the oxidative stability decreased with increasing degree of unsaturation in organic solvent whereas in liposomes, increased with increasing degree of unsaturation due to tight packed configuration. In this study, phenolic acids were found to render protections for PUFAs in modified PCs from oxidation. Modified PCs may have great potential for applications in food, cosmetic and pharmaceutical industries.

Hydrolysis of oxidized phosphatidylcholines by crude enzymes from chicken, pork and beef muscles.

Crude enzymes were extracted from beef, pork and chicken and were employed to hydrolyze 1-palmitoyl-2-linoleoyl-phosphatidylcholine (PLPC) and oxidized PLPC, i.e. hydroperoxide of PLPC (PLPC-OOH) and hydroxide of PLPC (PLPC-OH). HPLC-ELSD and ESI-MS were used to characterize and determinate hydrolytic products. After hydrolysis at 37 °C for 180 min, 26.8 ~ 27.4%, 21.6 ~ 22.8% and 17.8 ~ 19.0% of substrates were hydrolyzed by crude enzymes from beef, pork and chicken, respectively. Phospholipase A2 (PLA2) was the major contributor to hydrolysis, which accounted for 47.8 ~ 49.6%, 45.8 ~ 48.7% and 46.6 ~ 46.8% of hydrolysis of PLPC, PLPC-OOH and PLPC-OH, respectively. Crude enzymes demonstrated almost same specificities towards PLPC, PLPC-OOH and PLPC-OH. Under actions of crude enzymes, hydroperoxyoctadecadienoic acids (HpODE) and hydroxyoctadecadienoic acids (HODE) were yielded as hydrolytic products of PLPC-OOH and PLPC-OH, respectively. These finding would be helpful to better understand the fate of hydroperoxides of phospholipids and formation of HODE during meat products manufacturing.

Changes of hydroxyl-linoleic acids during Chinese-style sausage processing and their relationships with lipids oxidation.

A Chinese-style sausage was processed using pork as the raw material. During the whole process, 13-hydroxyoctadecadienoic acid (13-HODE), 9-hydroxyoctadecadienoic acid (9-HODE), 9,10-dihydroxyoctadecenoic acid (9,10-DHODE) and 9,10,13-trihydroxyoctadecenoic acid (9,10,13-THODE) kept increasing. All of them were found to be correlated negatively and significantly with lipoxygenases (LOX) activity, and positively and significantly with peroxide value (POV) and thiobarbituric acid reactive substances (TBARS). The ratio of 13-HODE to 9-HODE decreased slowly during drying stage and stayed higher than 2 during the whole process, and it was found to be positively and significantly with LOX activity. The ratio of variation of 13-HODE to variation of 9-HODE in every sampling period (the ratio of Δ13-HODE to Δ9-HODE) decreased sharply from 2.75 in the stage of curing for 12 h to 1.37 in the stage drying from 24 d to 30 d. The changes of ratio of 13HODE to 9-HODE and ratio of Δ13-HODE to Δ9-HODE indicated LOX-catalyzed oxidation predominated in curing and early drying stages, and such predominance was taken over by non-enzymatic oxidation during late drying stage; LOX-catalyzed oxidation was the major contributor to lipids oxidation during the whole process of the Chinese-style sausage preparing.

Interaction of Hsp90AA1 with phospholipids stabilizes membranes under stress conditions.

During heat shock conditions, structural changes in cellular membranes may lead to cell death. Hsp90AA1 and other heat shock proteins involved in membranes are responsible for protecting membrane stabilization. However, the membrane binding mechanism of Hsp90AA1 remains largely uncharacterized. In this study, we showed Hsp90AA1 interacts with phospholipid membrane with high affinity. Using the depth-dependent fluorescence-quenching with brominated lipids, we found Hsp90AA1 penetrated 10.7 Šinto the hydrocarbon core of the lipid bilayer. Circular dichroism spectra studies showed Hsp90AA1 lost part of its α-helical structures upon interaction with phospholipid membrane. By assessing binding properties of the three Hsp90AA1 domains, we found Hsp90AA1 interacted into the lipid bilayer mainly toward its C-terminus domain (CTD). Using scanning electron microscopy, we examined the protection on host cell membrane by overexpressing Hsp90AA1. The results indicated Hsp90AA1 or Hsp90AA1-CTD expressing E. coli cells exhibited better membrane integrity compared to the control after thermal treatment. The following liposome leakage assay suggested the protection of Hsp90AA1 might due to its stabilization of the membrane lipid. Collectively, the present study demonstrates Hsp90AA1 embeds into the lipid bilayer through its C-terminal domain and the Hsp90AA1-lipid association potentially has a significant function in keeping membranes stabilization during stress conditions.

Construction of Chitosan-Zn-Based Electrochemical Biosensing Platform for Rapid and Accurate Assay of Actin.

This work reports a study on the development of a sensitive immunosensor for the assay of actin, which is fabricated using sensing material chitosan-Zn nanoparticles (NPs) and anti-actin modified on glassy carbon electrode respectively. The prepared materials were characterized using transmission electron microscope (TEM), fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) spectra, and circular dichroism (CD) techniques. Meanwhile, the electrochemical properties were studied by linear sweep voltammetric (LSV), electrochemical impedance spectra (EIS), and differential pulse voltammetry (DPV). According to the experiments, under the optimum conditions, the linear fitting equation was I (µA) = -17.31 + 78.97c (R² = 0.9948). The linear range was from 0.0001 to 0.1 mg/mL and the detection limit (LOD, S/N = 3) was 21.52 ng/mL. The interference studies were also performed for checking the sensors' selectivity to actin. With better properties of the chitosan-Zn NPs, the modified electrode is considered as a better candidate than Western blot or immunohistochemical method for real-time usability. The detection limit reported is the lowest till date and this method provides a new approach for quality evaluation.

Interaction of heat shock protein 90 B1 (Hsp90B1) with liposome reveals its potential role in protection the integrity of lipid membranes.

Heat shock proteins of 90kDa (Hsp90) are molecular chaperones essential for protein homeostasis. Besides chaperone activity, Hsp90 exhibits other cellular functions at membranes, yet how it interacts with membranes remains elusive. We report here that Hsp90B1 interacts with phospholipid membranes. We first cloned the full-length open reading frame of Hsp90B1 from Anas platyrhnchos (ApHsp90B1), and the gene was then heterologously expressed and purified. SPR analysis show the purified ApHsp90B1 interacts with phospholipid membranes with high affinity (KD 176±25nM), and the interaction occurs over a wide range of pH, which is especially distinct under acidic conditions. Tryptophan fluorescence and far-UV CD spectra studies find that the interaction of ApHsp90B1 with phospholipid membrane induces microenvironment changes of tryptophan residues and conformational change of some regions in ApHsp90B1, which might be the reason of its increased ATPase activity upon addition phospholipid vesicles. Importantly, the interaction of ApHsp90B1 with phospholipid vesicles significantly reduces lipolysis of the membrane phospholipid, suggesting that the interaction of Hsp90B1 with membrane could preserve membrane integrity. The present study therefore demonstrates for the first time that Hsp90B1 exhibits high affinity for phospholipid membrane and suggest Hsp90B1 play an important role in membrane-stabilizing via its interaction with membrane phospholipids.

Interaction of Hsp90 with phospholipid model membranes.

Heat shock protein 90 (Hsp90) is an essential molecular chaperone with versatile functions in cell homeostatic control under both normal and stress conditions. Hsp90 has been found to be expressed on the cell surface, but the mechanism of Hsp90 association to the membrane remains obscure. In this study, the direct interaction of Hsp90 and phospholipid vesicles was characterized, and the role of Hsp90 on membrane physical state was explored. Using surface plasmon resonance (SPR), we observed a strong interaction between Hsp90 and different compositions of lipid. Hsp90 had a preference to bind with more unsaturated phospholipid species and the affinity was higher with negatively charged lipids than zwitterionic lipids. Increasing the mole fraction of cholesterol in the phospholipid led to a decrease of binding affinity to Hsp90. Circular dichroism (CD) spectroscopy of Hsp90 in PC membranes showed more α-helix structure than in aqueous buffer. The differential scanning calorimeter (DSC) and fluorescence polarization results showed Hsp90 could affect the transition temperature and fluidity of the bilayer. We postulate from these results that the association between Hsp90 and membranes may involve both electrostatic and hydrophobic force, and constitute a possible mechanism that modulates membrane lipid order during thermal fluctuations.

Effect of heat shock protein 90 against ROS-induced phospholipid oxidation.

The antioxidative role of Hsp90 purified from duck muscle on phospholipid was investigated in this study. Lipid oxidation was assessed by ferric thiocyanate method, and particle size, zeta potential measurements and transmission electron microscopy were employed to detect physical and chemical changes during oxidation of liposomes. Increase of the peroxidation products, decrease of the particle size and disruption of the spherical unity of the liposomes were detected when liposome was exposed to hydrogen peroxide (H2O2) oxidation, and Hsp90 was shown to protect liposome against oxidation. To further test the protection of Hsp90 on cell membrane, the Hsp90 transformed E. coli cell model was built. The Hsp90-containing E. coli showed higher survival and better membrane integrity as compared to the control upon H2O2 exposure. It is expected that Hsp90 plays an important role in the prevention of phospholipids oxidation in meat and has potential use as a food antioxidant.

Optimization and physicochemical properties of nutritional protein isolate from pork liver with ultrasound-assisted alkaline extraction.

The aim of this study was to investigate the optimal conditions of ultrasound-assisted alkaline extraction (UAAE) on pork liver protein isolate (UPLPI) and its physico-chemical properties. Response surface methodology was used to determine the optimal conditions for UAAE, which were at ultrasonic power 265 W, ultrasonic time 42 min, NaOH concentration 0.80%, temperature 50°C, and solvent/raw material ratio 70. The extraction yield and efficiency of UPLPI were significantly improved over the conventional alkaline extraction (PLPI). The results of amino acid composition showed that UAAE could increase serine (36.5 g/kg), arginine (38.1 g/kg), alanine (37.5 g/kg), proline (48.7 g/kg), phenylalanine (55.6 g/kg) and lysine (47.2 g/kg) elution amount. The changes in fourier transform infrared spectra indicated unfolding and destruction of the protein structure in UPLPI. The differential scanning calorimetry analysis presented UPLPI with a slightly lower onset and peak denaturation temperature over PLPI. Surface hydrophobicity increased and the microstructures presented larger and more pores of UPLPI, therefore, it had better in vitro digestibility than PLPI. Therefore, UPLPI might have a potential application prospect in the food field due to its changes on molecular structure as well as on the microstructure of protein by UAAE.

Differential expression of heat shock protein 90, 70, 60 in chicken muscles postmortem and its relationship with meat quality.

OBJECTIVE: The aim of this study was to investigate the expression of heat shock protein (HSP) 90, 70, and 60 in chicken muscles and their possible relationship with quality traits of meat. METHODS: The breast muscles from one hundred broiler chickens were analyzed for drip loss and other quality parameters, and the levels of heat shock protein (HSP) 90, 70, and 60 were determined by immunoblots. RESULTS: Based on the data, chicken breast muscles were segregated into low (drip loss≤5%), intermediate (5%0.05). CONCLUSION: Results of this study suggests that higher levels of HSP90 and HSP60 may be advantageous for maintenance of cell function and reduction of water loss, and they could act as potential indicator for better water holding capacity of meat.

Simultaneous determination of Ltx and Ltxd in cured meat products by LC/MS/MS.

9,10-Epoxyoctadec-12-enoic acid (Ltx) and 9,10-dihydroxy-12-octadecenoic acid (Ltxd), oxidation products of Linoleic acid, are of biological significance. In this paper, a method was developed for simultaneous determination of Ltx and Ltxd in cured meat products. The analytes were separated by high performance liquid chromatography and detected with tandem mass spectrometry. The method was of satisfactory performances with the quantification limits of 0.64µg/g and 0.025µg/g for Ltx and Ltxd, respectively. The method was employed to detect the analytes in cured meat products, and 21 out 26 samples were found to contain Ltx and Ltxd simultaneously, in ranges of 0.77-6.90µg/g and 0.17-3.93µg/g, respectively. The result also indicated there were isomers of Ltx and Ltxd in samples, and the final amount of Ltxds after ingestion might be much higher than those originally detected in cured meats. More attention should be paid to Ltxs and Ltxds in cured meat products.