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1.
Food Chem ; 311: 125900, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31780223

RESUMO

Nucleotide degradation in fish is an important biochemical change after death, which is closely related to freshness and sensory quality. However, except ATP-relative nucleotides, it remains unclear about changes in other nucleotide metabolites during postmortem stage. In this study, a strategy for the simultaneous quantification of 28 nucleobases, nucleosides, and nucleotides using hydrophilic interaction chromatography coupled with tandem mass spectrometry (HILIC-MS/MS) with positive/negative ion switching was developed. This method showed good linearity, precision, repeatability, and recovery. Furthermore, it was successfully applied to monitor the postmortem nucleotide degradation of turbot mince during chill (4 °C) and partial freezing (-3 °C) storage for 168 h. It was noted that the patterns of the changes in nucleotide metabolites differed considerably depending on the storage temperature. Meanwhile, the different pathway and speed of nucleotide catabolism in turbot mince was summarized based on the quantification data.


Assuntos
Produtos Pesqueiros/análise , Músculos/metabolismo , Nucleosídeos/química , Animais , Cromatografia Líquida de Alta Pressão , Linguados/metabolismo , Congelamento , Interações Hidrofóbicas e Hidrofílicas , Músculos/química , Nucleosídeos/metabolismo , Nucleotídeos/química , Nucleotídeos/metabolismo , Espectrometria de Massas em Tandem
2.
J Phys Condens Matter ; 32(8): 085403, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31693999

RESUMO

Tungsten (W) oxides have shown broad applications such as photocatalyst and cathode of lithium ion batteries. It is well-known that pressure can induce structural phase transition, producing novel properties. On the other hand, the study of W oxides under high pressures is beneficial for the control of the oxygen fugacity. In this work, we built the high-pressure phase diagram of W-O binary compounds through first-principles swarm-intelligence structural search calculations. WO2 and WO3 are stable in the whole considered pressure range from 0 to 300 GPa. Besides reproducing the known structures, we identify two new phases of WO2 (e.g. C2/m and Cmca) and three ones for WO3 (e.g. Pnma, Cmcm, and Pm-3n), associating with the evolution of polyhedron (i.e. octahedron → distorted octahedron for WO2, and octahedron → hendecahedron → tetradecahedron → icosahedron for WO3). More interestingly, the Pm-3n-structured WO3 shows the highest coordination number of 12. Electron structure calculations indicate that pressure-induced nonmetal → metal transition occurs for WO2 and WO3. Our study provides an opportunity to understand the structures and electronic properties of W-O system under high pressure.

3.
J Agric Food Chem ; 67(25): 7174-7182, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31240931

RESUMO

Intake of endocrine-disrupting chemicals (EDCs) by humans could disturb the metabolism of hormones, induce cancer, and damage the liver and other organs. Phthalate acid esters (PAEs) and alkylphenols (APs) are important EDCs and environmental contaminants. With the increasing use of plastics and nonionic surfactants worldwide, PAEs and APs have entered environmental water and accumulated in edible fish, which are finally consumed by humans. In this study, a coated direct inlet probe (CDIP) based on an atmospheric solid analysis probe, which can rapidly and simultaneously extract both PAEs and APs in fish, was developed. Twelve PAEs and APs were quantified by using a stable-isotope-labeled internal standard. Standard curves of the PAEs and APs having correlation coefficients of R2 ≥ 0.9837 were obtained. The limit of detection of the PAEs and APs was distributed from 0.01 to 40 ng g-1. The relative recovery of the method was 78-120% between low, medium, and high spiked levels. Combined with principal component analysis, PAE- and AP-contaminated Carassius auratus from different habitats could be identified. Multiple sample analysis mode allowed the extraction of up to 12 samples at once, and the total analysis time (including sample pretreatment, extraction, and analysis time) was less than 10 min per sample, which indicates that CDIP is useful for rapid quantitative analysis.


Assuntos
Ésteres/análise , Carpa Dourada , Ensaios de Triagem em Larga Escala/métodos , Fenóis/análise , Ácidos Ftálicos/análise , Animais , Disruptores Endócrinos/análise , Disruptores Endócrinos/isolamento & purificação , Ésteres/isolamento & purificação , Carpa Dourada/metabolismo , Ensaios de Triagem em Larga Escala/instrumentação , Limite de Detecção , Fenóis/isolamento & purificação , Ácidos Ftálicos/isolamento & purificação , Extração em Fase Sólida
4.
Phys Rev Lett ; 122(9): 097002, 2019 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-30932540

RESUMO

Electrides are unique compounds where most of the electrons reside at interstitial regions of the crystal behaving as anions, which strongly determines its physical properties. Interestingly, the magnitude and distribution of interstitial electrons can be effectively modified either by modulating its chemical composition or external conditions (e.g., pressure). Most of the electrides under high pressure are nonmetallic, and superconducting electrides are very rare. Here we report that a pressure-induced stable Li_{6}P electride, identified by first-principles swarm structure calculations, becomes a superconductor with a predicted superconducting transition temperature T_{c} of 39.3 K, which is the highest among the already known electrides. The interstitial electrons in Li_{6}P, with dumbbell-like connected electride states, play a dominant role in the superconducting transition. Other Li-rich phosphides, Li_{5}P, Li_{11}P_{2}, Li_{15}P_{2}, and Li_{8}P, are also predicted to be superconducting electrides, but with a lower T_{c}. Superconductivity in all these compounds can be attributed to a combination of a weak electronegativity of phosphorus (P) with a strong electropositivity of lithium (Li), and opens up the interest to explore high-temperature superconductivity in similar binary compounds.

5.
J Chromatogr A ; 1596: 20-29, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-30885403

RESUMO

The coated direct inlet probe (CDIP) is a new laboratory-made low-cost technology developed from a direct inlet probe (DIP), which has the advantage of quick enrichment/cleanup of an analyte from liquid samples. A capillary probe is coated with hydroxy-terminated polydimethylsiloxane (OH-PDMS), divinylbenzene (DVB), and ß-cyclodextrin (ß-CD) by a sol-gel method. This probe can be directly coupled with a commercialized atmospheric-pressure chemical ionization (APCI) ion source and high-resolution mass spectrometry, which are widely applicable, reliable, and durable. The ability to perform quantitative analyses with the use of a stable-isotope-labeled internal standard (SIL-IS) was tested by using different concentrations of acenaphthylene (ACY), acenaphthene (ACP), fluorene (FLR), fluoranthene (FLT), phenanthrene (PHE), and benzo[a]pyrene (B[a]P). Calibration curves with a coefficient of determination of R2 ≥ 0.9982 for different polycyclic aromatic hydrocarbons (PAHs) were obtained. A limit of detection (LOD) of 0.008-0.04 ng mL-1 for PAHs was determined. The entire workflow is solvent-free and can be completed in less than 5 min, which demonstrates the advantages of this technique for quantitative analysis.


Assuntos
Técnicas de Química Analítica/instrumentação , Técnicas de Química Analítica/métodos , Espectrometria de Massas , Hidrocarbonetos Policíclicos Aromáticos/análise , Pressão Atmosférica , Calibragem , Limite de Detecção , Espectrometria de Massas/instrumentação
6.
J Am Chem Soc ; 141(13): 5409-5414, 2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30864432

RESUMO

An important goal in chemistry is to prepare F-rich transition metal fluorides due to the high oxidation states and potential applications such as oxidating and fluorinating agents. Thus far, the highest F stoichiometry in the neutral transition metal fluorides is 7. Here, we identify a hitherto unknown IrF8 compound through first-principles swarm-intelligence structure search calculations under high pressure. The three identified IrF8 phases exhibit typical molecular crystal characters, showing +8 oxidation state in Ir. The spatial symmetry of the basic building block in the three IrF8 phases gradually increases with pressure (e.g., dodecahedron [Formula: see text] square antiprism [Formula: see text] quasicube). The pressure-induced faster increase of Ir 5d orbital energy level with respect to F 2p provides a strong charge transfer driving force from Ir 5d to F 2p, facilitating the formation of F-rich compounds. More interestingly, the predicted electron affinities of the three predicted IrF8 phases are comparable/larger than that of PtF6, the strongest oxidation agent in the third row transition metal hexafluorides. The built high-pressure phase diagram of Ir-F binary compounds provides useful information for experimental synthesis.

7.
J Am Chem Soc ; 141(4): 1599-1605, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30608679

RESUMO

Graphene and phosphorene are two major types of atomically thin two-dimensional materials under extensive investigation. However, the zero band gap of graphene and the instability of phosphorene greatly restrict their applications. Here, we make first-principle unbiased structure search calculations to identify a new buckled graphene-like PC6 monolayer with a number of desirable functional properties. The PC6 monolayer is a direct-gap semiconductor with a band gap of 0.84 eV, and it has an extremely high intrinsic conductivity with anisotropic character (i.e., its electron mobility is 2.94 × 105 cm2 V-1 s-1 along the armchair direction, whereas the hole mobility reaches 1.64 × 105 cm2 V-1 s-1 along the zigzag direction), which is comparable to that of graphene. On the other hand, PC6 shows a high absorption coefficient (105 cm-1) in a broad band, from 300 to 2000 nm. Additionally, its direct band gap character can remain within a biaxial strain of 5%. All these appealing properties make the predicted PC6 monolayer a promising candidate for applications in electronic and photovoltaic devices.

8.
Chem Asian J ; 13(19): 2781-2785, 2018 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-29969186

RESUMO

Three-arm star azopyridinium salts self-organize into various morphologies in water/organic mixed solvents. Interesting AIE and self-assembling features are observed due to the strong interaction of the azopyridinium moieties with the highly polar H2 O molecules causing the salts to aggregate, which restricts the molecular motion and induces the fluorescence.

9.
J Am Chem Soc ; 140(18): 5962-5968, 2018 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-29693395

RESUMO

Sodium-ion batteries (SIBs) have attracted considerable attention due to the intrinsic safety and high abundance of sodium. However, the lack of high-performance anode materials becomes a main obstacle for the development of SIBs. Here, we identify an ideal anode material, a metallic TiC3 monolayer with not only remarkably high storage capacity of 1278 mA h g-1 but also low barrier energy and open-circuit voltage, through first-principles swarm-intelligence structure calculations. TiC3 still keeps metallic after adsorbing two-layer Na atoms, ensuring good electrical conductivity during the battery cycle. Besides, high melting point and superior dynamical stability are in favor of practical application. Its excellent performance can be mainly attributed to the presence of an unusual n-biphenyl unit in the TiC3 monolayer. High cohesive energy, originating from multibonding coexistence (e.g., covalent, ionic, and metal bonds) in the TiC3 monolayer, provides strong feasibility for experimental synthesis. In comparison with TiC3, functionalized TiC3 with oxygen shows a higher storage capacity; meanwhile, it keeps nearly the same barrier energy. This is in sharp contrast with metal-rich MXenes. These intriguing properties make the TiC3 monolayer a promising anode material for SIBs.

10.
J Phys Condens Matter ; 29(39): 394002, 2017 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-28825916

RESUMO

In this review, we show that the evolution of the microstructure and kinetics of ferroelastic crystals under external shear can be explored by computer simulations of 2D model materials. We find that the nucleation and propagation of twin boundaries in ferroelastics depend sensitively on temperature. In the plastic regime, the evolution of the ferroelastic microstructure under strain deformation maintains a stick-and-slip mechanism in all temperature regimes, whereas the dynamic behavior changes dramatically from power-law statistics at low temperature to a Kohlrausch law at intermediate temperature, and then to a Vogel-Fulcher law at high temperature. In the yield regime, the distribution of jerk energies follows power-law statistics in all temperature regimes for a large range of strain rates. The non-spanning avalanches in the yield regime follow a parabolic temporal profile. The changes of twin pattern and twin boundaries density represent an important step towards domain boundary engineering.

11.
Phys Chem Chem Phys ; 19(34): 23492-23496, 2017 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-28829071

RESUMO

Developing nanoelectronic engineering requires two-dimensional (2d) materials with both usable carrier mobility and proper large band-gap. In this study, we present a detailed theoretical investigation of the intrinsic carrier mobilities of buckled 2d GaN. This buckled 2d GaN is accessed by hydrofluorination (FGaNH) and hydrogenation (HGaNH). We predict that the anisotropic carrier mobilities of buckled 2d GaN can exceed those of 2d MoS2 and can be altered by an alterable surface chemical bond (convert from a Ga-F-Ga bond of FGaNH to a Ga-H bond of HGaNH). Moreover, converting FGaNH to HGaNH can significantly suppress hole mobility (even close to zero) and result in a transition from a p-type-like semiconductor (FGaNH) to an n-type-like semiconductor (HGaNH). These features make buckled 2d GaN a promising candidate for application in future conductivity-adjustable electronics.

12.
Molecules ; 21(11)2016 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-27854344

RESUMO

We aimed to explore the differences of thermal behaviors between insoluble collagen fibrils (ICFs) and pepsin-solubilized collagens (PSCs) from sea cucumber Stichopus japonicus. The unfolding/refolding sequences of secondary structures of ICFs and PSCs during the heating and cooling cycle (5 → 70 → 5 °C) were identified by Fourier transform infrared spectrometry combined with curve-fitting and 2D correlation techniques. ICFs showed a higher proportion of α-helical structures and higher thermostability than PSCs, and thus had more-stable triple helical structures. The sequences of changes affecting the secondary structures during heating were essentially the same between ICFs and PSCs. In all cases, α-helix structure was the most important conformation and it disappeared to form a ß-sheet structure. In the cooling cycle, ICFs showed a partially refolding ability, and the proportion of ß-sheet structure rose before the increasing proportion of α-helix structure. PSCs did not obviously refold during the cooling stage.


Assuntos
Colágeno/química , Redobramento de Proteína , Desdobramento de Proteína , Pepinos-do-Mar/química , Espectroscopia de Infravermelho com Transformada de Fourier , Aminoácidos , Animais , Desnaturação Proteica , Termodinâmica
13.
Artigo em Inglês | MEDLINE | ID: mdl-27690079

RESUMO

The antioxidant properties of l-arginine (l-Arg) in vivo, and its effect on enhancing resistance to oxidative stress and heat stress in Caenorhabditis elegans were investigated. C. elegans, a worm model popularly used in molecular and developmental biology, was used in the present study. Here, we report that l-Arg, at a concentration of 1 mM, prolonged C. elegans life by 26.98% and 37.02% under oxidative and heat stress, respectively. Further experiments indicated that the longevity-extending effects of l-Arg may be exerted by its free radical scavenging capacity and the upregulation of aging-associated gene expression in worms. This work is important in the context of numerous recent studies that concluded that environment stresses are associated with an increased population death rate.

14.
PLoS One ; 11(7): e0159938, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27455060

RESUMO

Recent studies have indicated that protein hydrolysates have broad biological effects. In the current study we describe a novel antioxidative peptide, FDPAL, from soybean protein isolate (SPI). The aim of this study was to purify and characterize an antioxidative peptide from SPI and determine its antioxidative mechanism. LC-MS/MS was used to isolate and identify the peptide from SPI. The sequence of the peptide was determined to be Phe-Asp-Pro-Ala-Leu (FDPAL, 561 Da). FDPAL can cause significant enhancement of resistance to oxidative stress both in cells as well as simple organisms. In Caenorhabditis elegans (C. elegans), FDPAL can up-regulate the expression of certain genes associated with resistance. The antioxidant activity of this peptide can be attributed to the presence of a specific amino acid sequence. Results from our work suggest that FDPAL can facilitate potential applications of proteins carrying this sequence in the nutraceutical, bioactive material and clinical medicine areas, as well as in cosmetics and health care products.


Assuntos
Antioxidantes/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Peptídeos/farmacologia , Proteínas de Soja/metabolismo , Animais , Animais Geneticamente Modificados , Antioxidantes/química , Antioxidantes/isolamento & purificação , Produtos Biológicos/química , Produtos Biológicos/metabolismo , Produtos Biológicos/farmacologia , Caenorhabditis elegans , Cromatografia , Regulação da Expressão Gênica , Concentração de Íons de Hidrogênio , Hidrólise , Oxirredução , Peptídeos/química , Peptídeos/isolamento & purificação , Espécies Reativas de Oxigênio , Proteínas de Soja/química , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Espectrometria de Massas em Tandem
15.
Int J Clin Exp Med ; 8(5): 7843-8, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26221338

RESUMO

The aim of this study was to compare the results of high ligation and stripping of the great saphenous vein (GSV) trunk combined with foam sclerotherapy with conventional surgery for the treatment of superficial venous varicosities of the lower extremity. One hundred and thirty eight patients with primary or secondary superficial venous varicosities of the lower extremity were included. 60 underwent conventional surgery and 78 were treated with high ligation and stripping of the GSV trunk and foam sclerotherapy of GSV branches, spider veins, and reticular veins. Surgical time and amount of bleeding of single limb, recurrence of varicose vein, complications and patients satisfactory were recorded. Compared with the conventional surgery group, the GSV trunk stripping and foam sclerotherapy group had a significantly lower surgical time (P < 0.05), amount of bleeding and duration of hospital stays (P < 0.01). No statistically significant difference with respect to the wound infection, local discomfort, postoperative recurrence rates of varicosity and patients satisfaction score was observed (P > 0.05). GSV trunk stripping and foam sclerotherapy group at a 6 months of follow up had a higher recurrence rate of varicosity as compared to the conventional surgery group (P < 0.05). High ligation and GSV trunk stripping combined with foam sclerotherapy prior to conventional surgery for patients with superficial venous varicosities of the lower extremity with a shorter surgical time, fewer bleeding, duration of hospital stays and higher patients satisfactory scores.

16.
Tumour Biol ; 35(6): 5227-35, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24515657

RESUMO

Methods for detecting circulating microRNAs (miRNAs), small RNAs that control gene expression, at high sensitivity and specificity in the blood have been reported in recent studies. The goal of this study was to determine if detectable levels of specific miRNAs are released into the circulation for bevacizumab-induced cardiotoxicity. A miRNA array analysis was performed using RNA isolated from 10 control patients in bevacizumab treatment, and n=10 patients have been confirmed to have bevacizumab-induced cardiotoxicity. From the array, we selected 19 candidate miRNA for a second validation study in 90 controls and 88 patients with bevacizumab-induced cardiotoxicity. Consistent with the data obtained from the microRNA array, circulating levels of five miRNAs were significantly increased in patients with bevacizumab-induced cardiotoxicity compared with controls. To confirm these data, we compared selected miRNAs in the plasma of patients with bevacizumab-induced cardiotoxicity with those of 66 patients with acute myocardial infarction (AMI). Moreover, we went on to analyze what factors may influence the levels of potential biomarker miRNAs. Consistent with the data obtained from the microRNA array, circulating levels of five miRNAs were significantly increased in patients with bevacizumab-induced cardiotoxicity compared with those of healthy bevacizumab treatment controls. However, only miRNA1254 and miRNA579 showed high specificity in the validation experiments. Moreover, we went on to analyze what factors may influence the levels of potential biomarker miRNAs. We identify two miRNAs that are specifically elevated in patients with bevacizumab-induced cardiotoxicity, miR1254 and miRNA579, and miRNA1254 shows the strongest correlation to the clinical diagnosis of bevacizumab-induced cardiotoxicity.


Assuntos
Inibidores da Angiogênese/efeitos adversos , Anticorpos Monoclonais Humanizados/efeitos adversos , Neoplasias Colorretais/tratamento farmacológico , Coração/efeitos dos fármacos , MicroRNAs/sangue , Idoso , Bevacizumab , Neoplasias Colorretais/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade
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