Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 61
Filtrar
Mais filtros

Bases de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Immunity ; 54(1): 132-150.e9, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33271119

RESUMO

HLA class I (HLA-I) glycoproteins drive immune responses by presenting antigens to cognate CD8+ T cells. This process is often hijacked by tumors and pathogens for immune evasion. Because options for restoring HLA-I antigen presentation are limited, we aimed to identify druggable HLA-I pathway targets. Using iterative genome-wide screens, we uncovered that the cell surface glycosphingolipid (GSL) repertoire determines effective HLA-I antigen presentation. We show that absence of the protease SPPL3 augmented B3GNT5 enzyme activity, resulting in upregulation of surface neolacto-series GSLs. These GSLs sterically impeded antibody and receptor interactions with HLA-I and diminished CD8+ T cell activation. Furthermore, a disturbed SPPL3-B3GNT5 pathway in glioma correlated with decreased patient survival. We show that the immunomodulatory effect could be reversed through GSL synthesis inhibition using clinically approved drugs. Overall, our study identifies a GSL signature that inhibits immune recognition and represents a potential therapeutic target in cancer, infection, and autoimmunity.


Assuntos
Ácido Aspártico Endopeptidases/metabolismo , Linfócitos T CD8-Positivos/imunologia , Glioma/imunologia , Glicoesfingolipídeos/metabolismo , Glicosiltransferases/metabolismo , Antígenos HLA/metabolismo , Antígenos de Histocompatibilidade Classe I/metabolismo , Imunoterapia/métodos , Apresentação de Antígeno , Ácido Aspártico Endopeptidases/genética , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Glioma/mortalidade , Glicoesfingolipídeos/imunologia , Antígenos HLA/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Humanos , Ativação Linfocitária , Transdução de Sinais , Análise de Sobrevida , Evasão Tumoral
3.
BMC Vet Res ; 20(1): 15, 2024 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-38184593

RESUMO

Fish live in an aquatic environment rich in various microorganisms and pathogens. Fish mucosal-associated lymphoid tissue (MALT) plays a very important role in immune defence. This study was conducted to characterize the immune response mediated by CcIgZ3 in common carp (Cyprinus carpio.) and investigate the proliferating CcIgZ3+ B lymphocytes in gill. We determined the expression of CcIgZ3 in many different tissues of common carp following stimulation by intraperitoneal injection of TNP-LPS (2,4,6-Trinitrophenyl hapten conjugated to lipopolysaccharide) or TNP-KLH (2,4,6-Trinitrophenyl hapten conjugated to Keyhole Limpet Hemocyanin). Compared with TNP-KLH, TNP-LPS can induce greater CcIgZ3 expression in the head kidney, gill and hindgut, especially in the gill. The results indicate that the gill is one of the main sites involved in the immune response mediated by CcIgZ3. To examine the distribution of CcIgZ3+ B lymphocytes, immunohistochemistry (IHC) experiments were performed using a polyclonal antibody against CcIgZ3. The results indicated that CcIgZ3 was detected in the head kidney, hindgut and gill. To further examine whether CcIgZ3+ B lymphocytes proliferate in the gills, proliferating CcIgZ3+ B cells were analysed by immunofluorescence staining using an anti-CcIgZ3 polyclonal antibody and an anti-PCNA monoclonal antibody. CcIgZ3 and PCNA (Proliferating Cell Nuclear Antigen) double-labelled cells in the gills were located within the epithelial cells of the gill filaments of common carp stimulated with TNP-LPS at 3 dps and 7 dps, and relatively more proliferating CcIgZ3+ B cells appeared in the gills of common carp at 7 dps. These data imply that CcIgZ3+ B cells in the gills might be produced by local proliferation following TNP-LPS stimulation. In summary, compared with those in TNP-KLH, CcIgZ3 preferentially affects the gills of common carp following challenge with TNP-LPS. CcIgZ3+ B cells proliferate in the gills to quickly produce the CcIgZ3 antibody. In addition, CcIgZ3+ B cells can be activated to induce a strong immune response very early locally in the gill and produce the antibody CcIgZ3, which helps exert an immune-protective effect. These results suggest that an effective vaccine can be designed to promote production of the mucosal antibody CcIgZ3.


Assuntos
Carpas , Animais , Antígeno Nuclear de Célula em Proliferação , Brânquias , Lipopolissacarídeos/farmacologia , Anticorpos , Haptenos , Imunidade
4.
BMC Musculoskelet Disord ; 25(1): 43, 2024 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-38195444

RESUMO

BACKGROUND: Previous research has shown that lymphocytes and cytokines can mediate bone metabolism. This study explored the clinical association and predictive ability of lymphocytes and cytokines levels for bone metabolism. METHODS: A total of 162 patients were enrolled in this study. The levels of N-terminal propeptide of type I procollagen (P1NP), ß-collagen degradation product (ß-CTX), total T lymphocytes, immature T lymphocytes, suppressor/cytotoxic T lymphocytes, helper/inducer T lymphocytes, B lymphocytes, natural killer (NK) cells, Interferon-gamma (IFN-γ), tumour necrosis factor-alpha (TNF-α), IFN-α, interleukin-1 beta (IL-1ß), IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, and IL12p70 were evaluated. The relationship between these lymphocyte subsets and cytokines with bone metabolic status was examined and their predictive ability for bone metabolic status was assessed. RESULTS: The principal component analysis (PCA) and correlation analysis results varied on differences in lymphocyte subsets and cytokines in various bone metabolism states. Differential analysis revealed significant differences in the absolute counts of B lymphocytes (P < 0.05), level of IL-12p70 (P < 0.05), and IL-8 (P < 0.001) at different P1NP levels. Significant differences were observed in the absolute counts of total T lymphocytes (P < 0.05), B lymphocytes (P < 0.05), the level of IL-6 (P < 0.05), the percentage of B lymphocytes (P < 0.01), and NK cells (P < 0.05) at different ß-CTX levels. Furthermore, the receiver operating characteristic (ROC) curve showed that the absolute count of B lymphocytes and levels of IL-12p70 and IL-8 could be used to evaluate bone formation states, while the absolute counts of T and B lymphocytes, level of IL-6, and percentages of NK cells and B lymphocytes could be used to evaluate bone resorption states. CONCLUSION: The bone metabolism status changed based on the lymphocyte subsets and cytokine levels. Differentially expressed lymphocytes and cytokines could be used to distinguish bone metabolism status.


Assuntos
Citocinas , Interleucina-6 , Humanos , Estudos Transversais , Estudos Retrospectivos , Interleucina-8 , Subpopulações de Linfócitos
5.
Int J Mol Sci ; 25(1)2023 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-38203412

RESUMO

Leaf color variations in tea plants were widely considered due to their attractive phenotypes and characteristic flavors. The molecular mechanism of color formation was extensively investigated. But few studies focused on the transformation process of leaf color change. In this study, four strains of 'Baijiguan' F1 half-sib generation with similar genetic backgrounds but different colors were used as materials, including Green (G), Yellow-Green (Y-G), Yellow (Y), and Yellow-Red (Y-R). The results of broadly targeted metabolomics showed that 47 metabolites were differentially accumulated in etiolated leaves (Y-G, Y, and Y-R) as compared with G. Among them, lipids were the main downregulated primary metabolites in etiolated leaves, which were closely linked with the thylakoid membrane and chloroplast structure. Flavones and flavonols were the dominant upregulated secondary metabolites in etiolated leaves, which might be a repair strategy for reducing the negative effects of dysfunctional chloroplasts. Further integrated analysis with the transcriptome indicated different variation mechanisms of leaf phenotype in Y-G, Y, and Y-R. The leaf color formation of Y-G and Y was largely determined by the increased content of eriodictyol-7-O-neohesperidoside and the enhanced activities of its modification process, while the color formation of Y-R depended on the increased contents of apigenin derivates and the vigorous processes of their transportation and transcription factor regulation. The key candidate genes, including UDPG, HCT, CsGSTF1, AN1/CsMYB75, and bHLH62, might play important roles in the flavonoid pathway.


Assuntos
Camellia sinensis , Camellia sinensis/genética , Camellia sinensis/metabolismo , Metaboloma , Folhas de Planta/metabolismo , Transcriptoma
6.
Eur J Immunol ; 51(3): 734-737, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33275281

RESUMO

A single model system for integrative studies on multiple facets of antigen presentation is lacking. PAKC is a novel panel of ten cell lines knocked out for individual components of the HLA class I antigen presentation pathway. PAKC will accelerate HLA-I research in the fields of oncology, infectiology, and autoimmunity.


Assuntos
Apresentação de Antígeno/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Autoimunidade/imunologia , Humanos , Neoplasias/imunologia , Transdução de Sinais/imunologia
7.
Opt Express ; 29(21): 32818-32825, 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34809104

RESUMO

Angle-resolved polarized (ARP) Raman spectroscopy can be utilized to characterize the Raman modes of two-dimensional layered materials based on crystal symmetry or crystal orientation. In this paper, the polarization properties of E 1 2g and A1g modes on the basal plane and edge plane of high purity 2H-MoS2 bulk crystal grown by chemical vapor transport (CVT) method were investigated by ARP Raman spectroscopy. The I and II type ARP Raman spectroscopy with four kinds of polarization configurations: αY, αX, ßY, and ßX were used to explore the intensity dependence of E 1 2g and A1g modes at different planes on the polarization direction of incident/scattered light. The results show that the E 1 2g and A1g modes exhibit different polarization properties dependent on the polarization of the incident laser and the in-plane rotation of the sample at different planes. The experimental results were confirmed and analyzed through theoretical calculation. Our work sheds light on the intriguing effect of the subtle atomic structure in stacked MoS2 layers on the resulting ARP Raman properties. This provides a reference for the study of other two-dimensional layered crystalline materials by ARP Raman spectroscopy.

8.
J Phys Chem A ; 125(28): 6263-6272, 2021 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-34236877

RESUMO

Organic-organic interactions play important roles in secondary organic aerosol formation, but the interactions are complex and poorly understood. Here, we use environmental molecular beam experiments combined with molecular dynamics simulations to investigate the interactions between methanol and nopinone, as atmospheric organic proxies. In the experiments, methanol monomers and clusters are sent to collide with three types of surfaces, i.e., graphite, thin nopinone coating on graphite, and nopinone multilayer surfaces, at temperatures between 140 and 230 K. Methanol monomers are efficiently scattered from the graphite surface, whereas the scattering is substantially suppressed from nopinone surfaces. The thermal desorption from the three surfaces is similar, suggesting that all the surfaces have weak or similar influences on methanol desorption. All trapped methanol molecules completely desorb within a short experimental time scale at temperatures of 180 K and above. At lower temperatures, the desorption rate decreases, and a long experimental time scale is used to resolve the desorption, where three desorption components are identified. The fast component is beyond the experimental detection limit. The intermediate component exhibits multistep desorption character and has an activation energy of Ea = 0.18 ± 0.03 eV, in good agreement with simulation results. The slow desorption component is related to diffusion processes due to the weak temperature dependence. The molecular dynamics results show that upon collisions the methanol clusters shatter, and the shattered fragments quickly diffuse and recombine to clusters. Desorption involves a series of processes, including detaching from clusters and desorbing as monomers. At lower temperatures, methanol forms compact cluster structures while at higher temperatures, the methanol molecules form layered structures on the nopinone surface, which are visible in the simulation. Also, the simulation is used to study the liquid-liquid interaction, where the methanol clusters completely dissolve in liquid nopinone, showing ideal organic-organic mixing.

9.
Indoor Air ; 31(2): 383-391, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-32939827

RESUMO

Building ventilation is important for occupants' health. There are few studies of associations between home ventilation and occupant's health in China. During 2013-2016, we measured ventilation in 399 homes in Tianjin and Cangzhou, China, and surveyed the health history of children. Ventilation rates were measured using mass balance of occupant generated CO2 . The associations of home ventilation with children's asthma and allergy were analyzed in different strata of time and space. A low bedroom ventilation at night was significantly associated with an increased proportion of rhinitis among children (rhinitis current, adjusted odds ratio (AOR): 1.59; 95% confidence interval (CI): 1.01-2.49; diagnosed rhinitis, AOR: 3.02 (1.16-7.89)). Our findings suggest a dose-response relationship between ventilation rate at night in children's bedrooms and rhinitis current. The night-time ventilation rate in bedrooms has a greater association with rhinitis than the whole home ventilation rate during daytime.


Assuntos
Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , Asma/epidemiologia , Hipersensibilidade/epidemiologia , Ventilação , Criança , China/epidemiologia , Exposição Ambiental , Habitação , Humanos , Respiração , Rinite , Fatores de Risco
10.
J Phys Chem A ; 124(51): 10879-10889, 2020 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-33319553

RESUMO

Accommodation of vapor-phase water molecules into ice crystal surfaces is a fundamental process controlling atmospheric ice crystal growth. Experimental studies investigating the accommodation process with various techniques report widely spread values of the water accommodation coefficient on ice, αice, and the results on its potential temperature dependence are inconclusive. We run molecular dynamics simulations of molecules condensing onto the basal plane of ice Ih using the TIP4P/Ice empirical force field and characterize the accommodated state from this molecular perspective, utilizing the interaction energy, the tetrahedrality order parameter, and the distance below the instantaneous interface as criteria. Changes of the order parameter turn out to be a suitable measure to distinguish between the surface and bulk states of a molecule condensing onto the disordered interface. In light of the findings from the molecular dynamics, we discuss and re-analyze a recent experimental data set on αice obtained with an environmental molecular beam (EMB) setup [Kong, X.; J. Phys. Chem. A 2014, 118 (22), 3973-3979] using kinetic molecular flux modeling, aiming at a more comprehensive picture of the accommodation process from a molecular perspective. These results indicate that the experimental observations indeed cannot be explained by evaporation alone. At the same time, our results raise the issue of rapidly growing relaxation times upon decreasing temperature, challenging future experimental efforts to cover relevant time scales. Finally, we discuss the relevance of the water accommodation coefficient on ice in the context of atmospheric cloud particle growth processes.

11.
J Phys Chem A ; 124(18): 3652-3661, 2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-32281376

RESUMO

Water and organics are omnipresent in the atmosphere, and their interactions influence the properties and lifetime of both aerosols and clouds. Nopinone is one of the major reaction products formed from ß-pinene oxidation, a compound emitted by coniferous trees, and it has been found in both gas and particle phases in the atmosphere. Here, we investigate the interactions between water molecules and nopinone surfaces by combining environmental molecular beam (EMB) experiments and molecular dynamics (MD) simulations. The EMB method enables detailed studies of the dynamics and kinetics of water interacting with solid nopinone at 170-240 K and graphite coated with a molecularly thin nopinone layer at 200-270 K. MD simulations that mimic the experimental conditions have been performed to add insights into the molecular-level processes. Water molecules impinging on nopinone surfaces are efficiently trapped (≥97%), and only a minor fraction scatters inelastically while maintaining 35-65% of their incident kinetic energy (23.2 ± 1.0 kJ mol-1). A large fraction (60-80%) of the trapped molecules desorbs rapidly, whereas a small fraction (20-40%) remains on the surface for more than 10 ms. The MD calculations confirm both rapid water desorption and the occurrence of strongly bound surface states. A comparison of the experimental and computational results suggests that the formation of surface-bound water clusters enhances water uptake on the investigated surfaces.

12.
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.

13.
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.

14.
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
15.
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.

16.
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.

17.
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.

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.
J Phys Chem A ; 118(22): 3973-9, 2014 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-24814567

RESUMO

The interaction of water vapor with ice remains incompletely understood despite its importance in environmental processes. A particular concern is the probability for water accommodation on the ice surface, for which results from earlier studies vary by more than 2 orders of magnitude. Here, we apply an environmental molecular beam method to directly determine water accommodation and desorption kinetics on ice. Short D2O gas pulses collide with H2O ice between 170 and 200 K, and a fraction of the adsorbed molecules desorbs within tens of milliseconds by first order kinetics. The bulk accommodation coefficient decreases nonlinearly with increasing temperature and reaches 0.41 ± 0.18 at 200 K. The kinetics are well described by a model wherein water molecules adsorb in a surface state from which they either desorb or become incorporated into the bulk ice structure. The weakly bound surface state affects water accommodation on the ice surface with important implications for atmospheric cloud processes.

20.
Zhonghua Yi Xue Za Zhi ; 94(32): 2506-9, 2014 Aug 26.
Artigo em Zh | MEDLINE | ID: mdl-25410921

RESUMO

OBJECTIVE: To evaluate the clinical values of T-lymphocyte cytokines in renal transplant acute rejection. METHODS: A total of 31 recipients with renal transplantation and 15 healthy volunteers from January 2010 to January 2012 were enrolled and divided into acute rejection group (n = 11) and stable renal allograft function group (n = 20) according to the inclusion criteria. Peripheral blood was collected from the patients before transplantation, 1, 7, 14, 28 day after transplantation and acute rejection onset. Cytometric bead array (CBA) was used to monitor the levels of interleukin-17 (IL-17), interferon-gamma (IFN-γ), tumor necrosis factor (TNF), interleukin(IL)-10, IL-6, IL-4 and IL-2. The associations of the changes and levels of cytokines in 3 groups were examined with Pearson correlation analysis. RESULTS: The levels of IL-17A, TNF, IL-10 and IL-2 in recipients before transplantation were (3.40 ± 1.29) , (1.79 ± 0.53) , (2.73 ± 0.65) and (1.79 ± 1.02) ng/L respectively and decreased significantly compared to healthy volunteers ((4.52 ± 2.01), (3.36 ± 1.09) , (3.91 ± 0.42) , (3.12 ± 1.07) ng/L respectively, all P < 0.05). However the levels of IFN-γ, IL-6 and IL-4 showed no significant changes between two groups (all P > 0.05). In acute rejection group after transplantation, the levels of IL-17A, IFN-γ, IL-10 and IL-6 were (9.47 ± 4.75) , (5.01 ± 2.23) , (12.20 ± 5.79) , (6.55 ± 3.45) ng/L respectively and increased significantly compared to the renal allograft function group ((4.39 ± 1.26), (2.90 ± 0.87),(5.68 ± 2.25) and (2.10 ± 0.70) ng/L respectively, all P < 0.05); the level of IL-17A was correlated with those of IFN-γ and IL-4 (Pearson r = 0.519, 0.395, both P < 0.01), the level of IFN-γ was correlated with those of IL-4 and IL-2 (r = 0.276, 0.335, all P < 0.05) , the level of TNF was correlated with that of IL-4 (r = 0.423, P < 0.05) and the level of IL-10 was correlated with that of IL-6 (r = 0.361, P < 0.05). CONCLUSIONS: Cytokines play an important role in acute rejection of renal transplant. And further understanding of its mechanism may provide experimental and preventive rationales.


Assuntos
Transplante de Rim , Linfócitos T , Citocinas , Humanos , Transplantados , Transplante Homólogo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA