Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sci Total Environ ; 719: 136965, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-32120090

RESUMO

Phthalates are SVOCs (Semi-volatile Organic Compounds) that are widely used in industrial and daily home products. This study aimed to investigate exposure levels to phthalates in Chinese homes and to relate these to building characteristics and lifestyles. Dust in 399 homes of 410 children in urban Tianjin and rural Cangzhou was analyzed for concentrations of six target phthalates. The median concentrations were 0.31µg/g for diethyl phthalate (DEP), 16.39µg/g for di-isobutyl phthalate (DiBP), 42.60µg/g for di-n-butyl phthalate (DnBP), 0.10µg/g for benzyl butyl phthalate (BBzP), 127.11µg/g for di (2-ethylhexyl) phthalate (DEHP) and 0.28µg/g for di-isononyl phthalate (DiNP). Strong associations were found between modern flooring materials (laminated wood/wood) and concentrations of DiBP, BBzP and DiNP; modern window frame (aluminum/plastic steel) and BBzP concentration; leather polish and DEHP concentration; perfume and DEP concentration. Concentrations of phthalates were significantly higher in Tianjin urban homes than Cangzhou rural homes. Concentrations of phthalates increased significantly with increasing household income. Our study indicates that exposure to phthalates in Chinese homes increases with attributes of modern life.

2.
J Hazard Mater ; 392: 122392, 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-32208307

RESUMO

To reduce the toxicity of vanadium(V) [V(V)] and inhibit the desorption of adsorbed vanadium in groundwater, we synthesized nanoscale zerovalent iron (nZVI) dispersed on layered double hydroxide (LDH) composites (nZVI@LDH) to remove V(V) from simulated groundwater. We found that nZVI@LDH could reduce high-valence vanadium to low-valence vanadium, then forming vanadium-containing precipitation to reduce the toxicity and inhibiting vanadium from returning to groundwater. SEM and XRD characterizations exhibited the uniform dispersal of nZVI on the surface of LDH. nZVI@LDH with nZVI/LDH at a mass ratio of 1:2 provided the maximum adsorption capacity of 93.7 mg g-1 at pH 3.0. Coexisting anions and dissolved oxygen in groundwater have little effect on V(V) removal. nZVI@LDH performed well across a wide pH range (3.0-8.0). The surface characterizations and XPS analysis revealed that LDH as supporting materials inhibited the aggregation and passivation of nZVI. The adsorbed V(V) was reduced to V(IV) and V(III) by nZVI and spontaneously transformed into insoluble VO2 and V2O3. The DFT calculations indicated the strong complexation and better stability of the V(IV) and V(III) species with nZVI@LDH than V(V). This work suggests that nZVI@LDH has the potential to serve as an efficient material for the immobilization of V(V) in groundwater.

3.
J Phys Chem Lett ; 10(23): 7433-7438, 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31725306

RESUMO

The interaction of water with TiO2 is of substantial scientific and technological interest as it determines the activity of TiO2 in photocatalytic and environmental applications in nanoparticle suspensions in water, in complex appliances, or in pure form interacting with water vapor. The influence of TiO2 nanoparticles on the hydrogen bonding structure of water molecules is an important factor that controls hydration of other species, reactions, or nucleation processes. We use a combination of ambient-pressure X-ray photoelectron spectroscopy and electron yield near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the oxygen K-edge to investigate the hydrogen bonding structure of adsorbed water on titania nanoparticles in equilibrium with nearly saturated water vapor at 235 K. The results clearly show that the net NEXAFS spectrum of adsorbed water resembles that of liquid, disordered water at 235 K, a temperature at which both homogeneous and heterogeneous freezing of bulk water is anticipated.

4.
Chemphyschem ; 20(17): 2171-2178, 2019 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-31194285

RESUMO

The processes of molecular clustering, condensation, nucleation, and growth of bulk materials on surfaces, represent a spectrum of vapor-surface interactions that are important to a range of physical phenomena. Here, we describe studies of the initial stages of methanol condensation on graphite, which is a simple model system where gas-surface interactions can be described in detail using combined experimental and theoretical methods. Experimental molecular beam methods and computational molecular dynamics simulations are used to investigate collision dynamics and surface accommodation of methanol molecules and clusters at temperatures from 160 K to 240 K. Both single molecules and methanol clusters efficiently trap on graphite, and even in rarified systems methanol-methanol interactions quickly become important. A kinetic model is developed to simulate the observed behavior, including the residence time of trapped molecules and the quantified Arrhenius kinetics. Trapped molecules are concluded to rapidly diffuse on the surface to find and/or form clusters already at surface coverages below 10-6 monolayers. Conversely, clusters that undergo surface collisions fragment and subsequently lose more loosely bound molecules. Thus, the surface mediates molecular collisions in a manner that minimizes the importance of initial cluster size, but highlights a strong sensitivity to surface diffusion and intermolecular interactions between the hydrogen bonded molecules.

5.
Mol Med Rep ; 19(5): 4238-4248, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30942398

RESUMO

Emerging evidence indicates that natural killer (NK) cells and NKT­like cells may affect allograft outcomes following solid organ transplantation. However, the roles of these cells in allograft acceptance and dysfunction are controversial. To assess the changes in NK cell and CD3+CD56+ NKT­like cell frequency and phenotype in renal allograft recipients and to explore their associations with acute T­cell­mediated renal allograft rejection (ACR), longitudinal changes in NK and NKT­like cell frequency and phenotype were characterized using flow cytometry and immunohistochemistry in the peripheral blood and kidney allograft tissues in 142 recipients undergoing kidney transplantation. The serum concentrations of NK cell­associated cytokines were also detected by cytokine multiplex immunoassay. In contrast to the healthy controls, recipients with stable graft function exhibited increased proportions of CD56brightCD16dim subsets and decreased proportions of NKT­like cells in their peripheral blood mononuclear cells (PBMCs). Patients with ACR demonstrated increased proportions of NK cells, which were associated with increased CD3­CD56bright subsets and decreased CD3­CD56dim subsets, an increase in the CD56bright/CD56dim ratio in PBMCs and increased CD56+ NK cell infiltration in the kidney allograft, compared with the stable controls. In addition, there was a decreased proportion of NKT­like cells in patients with ACR, and an increased ratio of CD56bright/NKT­like cells compared with the stable controls. These differences appeared to be consistent with the increase in the serum concentrations of C­C motif chemokine 19 and the decrease in the serum concentrations of interleukin­15. These data indicate that CD56bright NK cells may promote the development of ACR, and that NKT­like cells may have immunoregulatory function. The results also imply that the CD56bright/CD56dim ratio may affect the ACR signatures.


Assuntos
Rejeição de Enxerto/imunologia , Transplante de Rim/efeitos adversos , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Linfócitos T/imunologia , Linfócitos T/metabolismo , Doença Aguda , Adulto , Biomarcadores , Antígeno CD56 , Citocinas/metabolismo , Feminino , Humanos , Imunofenotipagem , Contagem de Linfócitos , Masculino , Pessoa de Meia-Idade
6.
Front Plant Sci ; 10: 179, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30863415

RESUMO

Lipid droplets (LDs) have been widely found from diverse species and exhibit diverse functions. It remains unexplored what potential roles they played in tea. To address this question, we analyzed the chemical composition and the dynamic changes of cytosolic LDs during leaf growth and diurnal cycle. Using TopFluor cholesterol and Nile Red staining we demonstrated that cytosolic LDs were heterogeneous in tea tree (Camellia sinensis cv. Tieguanyin); the size and number of LDs increased with leaf growth. Compositional analysis showed that terpenoid esters and diacylglycerol are the major components of cytosolic LDs. The contents of total sterol esters (SEs) and ß-amyrin esters increased with leaf expansion and growth; individual SE also showed diurnal changes. Our data suggest that cytosolic LDs from tea tree leave mainly serve as storage site for free sterols and triterpenoids in the form of esters. Cytosolic LDs were not the major contributors to the aroma quality of made tea.

7.
Int Arch Occup Environ Health ; 92(4): 587-598, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30627853

RESUMO

PURPOSE: In the past 60 years, the prevalences of asthma and allergy among children have increased around the world. Neither genetic nor outdoor environmental factors can explain this increase. METHODS: We performed a cross-sectional study of 7366 children in Tianjin, China, on associations of home environment and lifestyles with asthma and allergy. RESULTS: The prevalences of diagnosed asthma, rhinitis and eczema among 0- to 8-year-old children in the Tianjin area were 4%, 9% and 39%. Home environment and lifestyle, together with infections, were strong risk factors. For asthma and allergy, the population attributable fraction (PAF) due to modern floors and wall coverings (i.e., laminated wooden floors and painted walls compared to tile floors and lime-coated walls) was 22%. Window condensation in winter and air conditioner use in summer, both of which are proxies for less ventilation, accounted for 7-17% of rhinitis and eczema. Cesarean delivery accounted for 10% of eczema symptoms. We developed a modern life index from appropriate home characteristics and lifestyle and food consumption habits and found it to have a clear dose-response relationship with asthma and allergy in Tianjin children. CONCLUSIONS: The results indicate that a "modern" home environment together with a modern lifestyle is associated with increased prevalences of asthma and allergies among children. Appropriate indoor environmental interventions and education of children's caregivers are important in the management of childhood asthma and allergy.


Assuntos
Asma/epidemiologia , Habitação , Hipersensibilidade/epidemiologia , Estilo de Vida , Asma/etiologia , Cesárea/efeitos adversos , Criança , Pré-Escolar , China/epidemiologia , Estudos Transversais , Eczema/epidemiologia , Eczema/etiologia , Exposição Ambiental/efeitos adversos , Feminino , Humanos , Hipersensibilidade/etiologia , Lactente , Recém-Nascido , Decoração de Interiores e Mobiliário , Masculino , Rinite Alérgica/epidemiologia , Rinite Alérgica/etiologia , Ventilação
8.
Phys Chem Chem Phys ; 21(3): 1141-1151, 2019 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-30607418

RESUMO

The interactions between water molecules and condensed n-butanol surfaces are investigated at temperatures from 160 to 240 K using the environmental molecular beam experimental method and complementary molecular dynamics (MD) simulations. In the experiments hyperthermal water molecules are directed onto a condensed n-butanol layer and the flux from the surface is detected in different directions. A small fraction of the water molecules scatters inelastically from the surface while losing 60-90% of their initial kinetic energy in collisions, and the angular distributions of these molecules are broad for both solid and liquid surfaces. The majority of the impinging water molecules are thermalized and trapped on the surface, while subsequent desorption is governed by two different processes: one where molecules bind briefly to the surface (residence time τ < 10 µs), and another where the molecules trap for a longer time τ = 0.8-2.0 ms before desorbing. Water molecules trapped on a liquid n-butanol surface are substantially less likely to escape from the surface compared to a solid layer. The MD calculations provide detialed insight into surface melting, adsorption, absorption and desorption processes. Calculated angular distributions and kinetic energy of emitted water molecules agree well with the experimental data. In spite of its hydrophobic tail and enhanced surface organization below the melting temperature, butanol's hydrophilic functional groups are concluded to be surprisingly accessible to adsorbed water molecules; a finding that may be explained by rapid diffusion of water away from hydrophobic surface structures towards more strongly bound conformational structures.

9.
Sci Rep ; 8(1): 14944, 2018 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-30297696

RESUMO

The goal of the present study was to compare the structural and compositional differences of cuticle between tender leaf and fully-expanded leaf in Camellia sinensis, and provide metabolic base for the further characterization of wax biosynthesis in this economically important crop species. The tender second leaf and the fully-expanded fifth leaf from new twig were demonstrated to represent two different developmental stages, their cuticle thickness were measured by transmission electron microscopy. The thickness of the adaxial cuticle on the second and fifth leaf was 1.15 µm and 2.48 µm, respectively; the thickness of the abaxial cuticle on the second and fifth leaf was 0.47 µm and 1.05 µm, respectively. The thickness of the epicuticular wax layer from different leaf position or different sides of same leaf were similar. However, the intracuticular wax layer of the fifth leaf was much thicker than that of the second leaf. Total wax lipids were isolated from the second leaf and the fifth leaf, respectively. Gas chromatography-mass spectrometry analysis identified 51 wax constituents belonging to 13 chemical classes, including esters, glycols, terpenoids, fatty acids and their derivatives. Wax coverage on the second and fifth leaf was 4.76 µg/cm2 and 15.38 µg/cm2, respectively. Primary alcohols dominated in the tender second leaf. However, triterpenoids were the major components from the fully-expanded fifth leaf. The predominant carbon chains varied depending on chemical class. These data showed that the wax profiles of Camellia sinensis leaves are development stage dependent, suggesting distinct developmental dependent metabolic pathways and regulatory mechanisms.


Assuntos
Camellia sinensis/química , Lipídeos/análise , Folhas de Planta/química , Chá/química , Ceras/química , Camellia sinensis/crescimento & desenvolvimento , Camellia sinensis/metabolismo , Camellia sinensis/ultraestrutura , Esterificação , Ésteres/análise , Ésteres/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura , Chá/crescimento & desenvolvimento , Chá/metabolismo , Chá/ultraestrutura , Terpenos/análise , Terpenos/metabolismo , Ceras/metabolismo
10.
Phys Chem Chem Phys ; 20(37): 24408-24417, 2018 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-30221299

RESUMO

Interactions between trace gases and ice are important in environmental chemistry and for Earth's climate. In particular, the adsorption of trace gases to ice surfaces at temperatures approaching the melting point has raised interest in the past, because of the prevailing pre-melting. Here, we present Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy data at ambient partial pressure of water to better define the onset temperature of pre-melting at the interfacial region of ice. Further, this study directly compares the interaction between an organic acid common in the atmosphere, formic acid, and that of an aliphatic carbon with ice at 253 K. It makes use of X-ray Photoelectron Spectroscopy (XPS) with its inherent narrow probing depth covering both the surface and near-surface bulk region when detecting electrons. We use the tender X-ray range for excitation to locate the organic species within the interfacial region with an extended probing depth compared to published XPS work. Electron kinetic energy dependent C1s photoemission data indicate that, at low coverage of a few 1014 molecules cm-2, the presence of formic acid is restricted to the upper ice layers of the interfacial region. Increasing the dosage, formic acid penetrates 6-7 nm into the air-ice interface. The presence of the more hydrophobic aliphatic carbon is restricted to the upper ice monolayers. This direct comparison of an organic acid with an aliphatic compound confirms the emerging picture where solutes enter the interfacial region of ice at a depth related to their specific tendency to form solvation shells.

11.
Oncol Lett ; 16(4): 4391-4399, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30214574

RESUMO

Nuclear factor κ-light-chain-enhancer of B cells (NF-κB) is one of the most important tumorigenic factors. Although it has been established that NF-κB is overly activated in human glioma cells, the molecular mechanisms that lead to the signal transduction to NF-κB and thereby the induction of resistance to apoptosis remain poorly understood. The present study demonstrated that mRNA and protein levels of E3 ubiquitin-protein ligase 2 (MIB2) were markedly upregulated in glioma cell lines and clinical samples. Immunohistochemical analysis also revealed high levels of MIB2 expression in glioma specimens. Ectopic overexpression of MIB2 was established in glioma cell lines to investigate its fundamental roles in the response of human glioma to apoptotic inducers. The results indicated that ultraviolet irradiation-induced cell apoptosis was inhibited with MIB2 overexpression in glioma cells. Notably, knockdown of MIB2 using RNA interference was able to increase the sensitivity of glioma cells to the pro-apoptotic agents. The present study identified that MIB2 induces NF-κB activation and facilitates the resistance of glioma cell to apoptosis. It was proposed that MIB2 may not only be an important hallmark to glioma disease progression, but that it may also offer novel clinical strategies to overcome resistance to cancer therapies.

12.
J Phys Chem A ; 122(21): 4861-4868, 2018 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-29741896

RESUMO

Processes involving atmospheric aerosol and cloud particles are affected by condensation of organic compounds that are omnipresent in the atmosphere. On ice particles, organic compounds with hydrophilic functional groups form hydrogen bonds with the ice and orient their hydrophobic groups away from the surface. The organic layer has been expected to constitute a barrier to gas uptake, but recent experimental studies suggest that the accommodation of water molecules on ice is only weakly affected by condensed short-chain alcohol layers. Here, we employ molecular dynamics simulations to study the water interactions with n-butanol covered ice at 200 K and show that the small effect of the condensed layer is due to efficient diffusion of water molecules along the surface plane while seeking appropriate sites to penetrate, followed by penetration driven by the combined attractive forces from butanol OH groups and water molecules within the ice. The water molecules that penetrate through the n-butanol layer become strongly bonded by approximately three hydrogen bonds at the butanol-ice interface. The obtained accommodation coefficient (0.81 ± 0.03) is in excellent agreement with results from previous environmental molecular beam experiments, leading to a picture where an adsorbed n-butanol layer does not alter the apparent accommodation coefficient but dramatically changes the detailed molecular dynamics and kinetics.

13.
PLoS One ; 13(5): e0197274, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29768461

RESUMO

This study aims to find out the relationship between pet keeping in childhood and asthma and allergy among children aged 0-8 years old in Tianjin, China. Parental or guardians reports of 7360 children were analyzed. 1490 (21.6%) families kept pets at the time of the survey (current), among them 4.0% cats, and 14.7% dogs. For the first year of life of children (early), 1196 (18.4%) families kept pets, and among them 3.2% cats, and 13.7% dogs. Exposure to a pet in early childhood significantly increased the risk of current wheeze, current dry cough, and diagnosed rhinitis. 17.9% of parents reported an avoidance behavior, i.e., had removed or refrained a pet due to asthma or allergy in the family. After adjustment for avoidance behavior, the negative effect of pet keeping on children's health became even more obvious, with e.g. an AOR of 3.37 (1.58-7.19) for diagnosed asthma, 3.60 (2.07-6.27) for diagnosed rhinitis, 1.92 (1.31-2.81) for diagnosed eczema. A dose-response relationship between pet keeping at current and current wheeze, current eczema and diagnosed eczema was found. In conclusion, pet exposure in early life of children in Tianjin is a risk factor for asthma and allergies among children aged 0-8 years old.


Assuntos
Asma/epidemiologia , Hipersensibilidade/epidemiologia , Animais de Estimação , Animais , Criança , Pré-Escolar , China/epidemiologia , Exposição Ambiental , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Fatores de Risco
14.
Macromol Biosci ; 18(2)2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29205878

RESUMO

Instability and poor targeting causes the long-term patency of RNA-modified tissue engineering blood vessels (TEBVs) remaining unsatisfactory. RNA can be enriched in exosome and then delivered into targeted cells while whether exosome-modified TEBVs achieve RNA targeted delivery is unclear. Here, to promote the expression of klotho protein on the mesenchymal stem cell (MSC)-derived exosomes, klotho plasmids are first transfected into MSCs, and adenosine kinase (ADK) siRNA is then loaded into exosome (klotho/ADK siRNA-exosome) using electrotransfection. Flow chamber results show that klotho/ADK siRNA-exosome can effectively capture circulating endothelial progenitor cells (EPCs). Besides, the captured EPCs can endocytose this exosome, and then decompose it into klotho protein and ADK siRNA. Moreover, ADK siRNA promotes the paracrine of proangiogenic factors and adenosine from EPCs, which further facilitate proliferation and migration of endothelial cells. Based on polyethyleneimine-capped gold nanoparticles, exosome-modified TEBVs are constructed through layer-by-layer assembly. Animal experimental results show that klotho/ADK siRNA-exosome-modified TEBVs can maintain the patency up to one month, and good endothelialization is observed. In short, one exosome-modified TEBV is constructed, capture molecules on the surface of exosome capture the circulating EPCs, and the loaded RNA achieves its purpose of accurate treatment depending on the needs of patients.


Assuntos
Vasos Sanguíneos/fisiologia , Células Progenitoras Endoteliais/metabolismo , Exossomos/metabolismo , Técnicas de Transferência de Genes , RNA Interferente Pequeno/administração & dosagem , Engenharia Tecidual/métodos , Adenosina Quinase/metabolismo , Animais , Movimento Celular , Proliferação de Células , Exossomos/ultraestrutura , Glucuronidase/metabolismo , Humanos , Ratos Wistar , Grau de Desobstrução Vascular
15.
J Phys Chem Lett ; 8(19): 4757-4762, 2017 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-28902513

RESUMO

The interfacial ionization of strong acids is an essential factor of multiphase and heterogeneous chemistry in environmental science, cryospheric science, catalysis research and material science. Using near ambient pressure core level X-ray photoelectron spectroscopy, we directly detected a low surface coverage of adsorbed HCl at 253 K in both molecular and dissociated states. Depth profiles derived from XPS data indicate the results as physisorbed molecular HCl at the outermost ice surface and dissociation occurring upon solvation deeper in the interfacial region. Complementary X-ray absorption measurements confirm that the presence of Cl- ions induces significant changes to the hydrogen bonding network in the interfacial region. This study gives clear evidence for nonuniformity across the air-ice interface and questions the use of acid-base concepts in interfacial processes.

16.
J Phys Chem A ; 121(35): 6614-6619, 2017 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-28792755

RESUMO

Water and organic molecules are omnipresent in the environment, and their interactions are of central importance in many Earth system processes. Here we investigate molecular-level interactions between water and a nopinone surface using an environmental molecular beam (EMB) technique. Nopinone is a major reaction product formed during oxidation of ß-pinene, a prominent compound emitted by coniferous trees, which has been found in both the gas and particle phases of atmospheric aerosol. The EMB method enables detailed studies of the dynamics and kinetics of D2O molecules interacting with a solid nopinone surface at 202 K. Hyperthermal collisions between water and nopinone result in efficient trapping of water molecules, with a small fraction that scatter inelastically after losing 60-80% of their incident kinetic energy. While the majority of the trapped molecules rapidly desorb with a time constant τ less than 10 µs, a substantial fraction (0.32 ± 0.09) form strong bonds with the nopinone surface and remain in the condensed phase for milliseconds or longer. The interactions between water and nopinone are compared to results for recently studied water-alcohol and water-acetic acid systems, which display similar collision dynamics but differ with respect to the kinetics of accommodated water. The results contribute to an emerging surface science-based view and molecular-level description of organic aerosols in the atmosphere.

17.
Sci Rep ; 7(1): 1322, 2017 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-28465534

RESUMO

Follicular regulatory T (Tfr) cell can effectively regulate humoral immunity, but its function and mechanism in antibody-mediated rejection (AMR) after organ transplantation remains unclear. Here we detected follicular helper T (Tfh) cell subsets in 88 renal transplant patients with chronic renal allograft dysfunction (40 with AMR and 48 without AMR). The ratio of Tfr cells in renal graft tissues and peripheral blood of AMR patients significantly decreased, while the ratio of IL-21-producing Tfh cells (Tfh2 and Tfh17) significantly increased, compared to non-AMR patients. When tested in functional assays, Tfr cells from both AMR and non-AMR patients exerted equivalent inhibitory function. Tfr cell transplantation or CTLA-4 virus transfection could significantly inhibit IL-21 secretion from Tfh cells of these patients, further suppress the proliferation and differentiation of B cells. CTLA-4 blocking, IL-10 and TGF-ß neutralization could partially weaken such inhibitory effect of Tfr cells. Besides, our study found that sirolimus reduced the ratio of Tfr cells, while cyclosporine and tacrolimus had no significant effect on Tfr cells. In a word, renal transplant patients with AMR have low proportion of Tfr cells but these cell exerted normal function.


Assuntos
Rejeição de Enxerto/imunologia , Transplante de Rim/efeitos adversos , Linfócitos T Reguladores/imunologia , Adulto , Anticorpos/imunologia , Linfócitos B/imunologia , Antígeno CTLA-4/imunologia , Diferenciação Celular , Proliferação de Células , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
18.
J Environ Manage ; 197: 331-337, 2017 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-28402915

RESUMO

A composite material consisting of nanoscale zerovalent iron particles supported on herb-residue biochar (nZVI/BC) was synthesized and used for treatment of Cr(VI)-contaminated water. The effects of initial pH, chromium concentration, contact time, and competition with coexisting anions and natural organic matter (NOM) were also investigated. nZVI/BC was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy analysis (SEM), and the Brunauer-Emmett-Teller surface area was measured. TEM and X-ray photoelectron spectroscopy (XPS) analysis before and after reaction with Cr(VI) showed that reduction and coprecipitation occurred during hexavalent chromium adsorption. The removal of Cr(VI) was highly pH-dependent and the adsorption kinetics data agreed well with the pseudo-second-order model. The presence of SO42- and humic acid promoted Cr(VI) removal at both low and high concentrations, while the HCO3- inhibited the reaction. These results prove that nZVI/BC can be an effective reagent for removal of Cr(VI) from solutions.


Assuntos
Carvão Vegetal , Cromo , Poluentes Químicos da Água , Ferro , Água
19.
Rev Sci Instrum ; 88(3): 035112, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28372415

RESUMO

Molecular beam techniques are commonly used to obtain detailed information about reaction dynamics and kinetics of gas-surface interactions. These experiments are traditionally performed in vacuum and the dynamic state of surfaces under ambient conditions is thereby excluded from detailed studies. Herein we describe the development and demonstration of a new vacuum-gas interface that increases the accessible pressure range in environmental molecular beam (EMB) experiments. The interface consists of a grating close to a macroscopically flat surface, which allows for experiments at pressures above 1 Pa including angularly resolved measurements of the emitted flux. The technique is successfully demonstrated using key molecular beam experiments including elastic helium and inelastic water scattering from graphite, helium and light scattering from condensed adlayers, and water interactions with a liquid 1-butanol surface. The method is concluded to extend the pressure range and flexibility in EMB studies with implications for investigations of high pressure interface phenomena in diverse fields including catalysis, nanotechnology, environmental science, and life science. Potential further improvements of the technique are discussed.

20.
Environ Sci Pollut Res Int ; 24(7): 6679-6687, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28083746

RESUMO

Magnetic biochar (M-BC) was derived from herbal medicine waste, Astragalus membranaceus residue, and was used as an adsorbent for ciprofloxacin removal from aqueous solutions. The M-BC was characterized by Brunauer-Emmett-Teller surface area analyses, Fourier transform infrared spectrometry, X-ray diffraction analysis, hysteresis loops, scanning electron microscopy energy-dispersive spectrometry, and X-ray photoelectron spectroscopy. The BET surface area increased from 4.40 to 203.70 m2/g after pyrolysis/magnetic modification. Batch experiments were performed at different dosages, initial concentrations, contact times, and solution pHs. Adsorption performances were evaluated using Langmuir and Freundlich isotherm models, and the results indicated that the Langmuir model appropriately described the adsorption process. The kinetic data were better fitted by a pseudo-second-order kinetic model. The maximum ciprofloxacin removal was observed at pH 6 (adsorption capacity of 68.9 ± 3.23 mg/g). Studies demonstrated that magnetically modified biochar might be an attractive, cost-effective, and easily separated adsorbent for contaminated water. Graphical abstract.


Assuntos
Carvão Vegetal/química , Ciprofloxacino/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Astragalus propinquus/química , Ciprofloxacino/química , Cinética , Fenômenos Magnéticos , Microscopia Eletrônica de Varredura , Espectroscopia Fotoeletrônica , Soluções , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Poluentes Químicos da Água/química , Purificação da Água/economia , Difração de Raios X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA