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1.
Chem Commun (Camb) ; 60(51): 6540-6543, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38841894

RESUMO

We report an efficient site-selective synthetic method to C2 and C3 indanyl-substituted indole derivatives via 1,3-dithianyl induced Nazarov-type cyclization. In particular, C2-selective indanyl-substituted indoles were directly obtained by a BF3·Et2O-promoted sequence of intramolecular C3-C2 migration and Nazarov-type cyclization process.

2.
Chem Commun (Camb) ; 60(10): 1285-1288, 2024 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-38197129

RESUMO

Herein, we reported an efficient indium catalyzed dithianyl-alkyne metathesis (DAM) reaction. This strategy allows for the formation of a new C-C double bond and valuable C-S bonds during the metathesis event, and was successfully applied to the synthesis of diverse vinyl dithianyl substituted organic molecules.

3.
Org Lett ; 26(3): 581-585, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38051762

RESUMO

Herein, we report a C3 and C1 coupling approach between vinyl 1,3-dithiane derivatives and alkynylsilanes for the construction of highly substituted conjugated dienes. Through the regioselective dual 1,3-sulfur migration process, this method enabled the synthesis of a wide range of highly substituted (E)-1,3-dienes stereoselectively in moderate to high yields, which provided one alternative way to synthesize the corresponding conjugated dienones.

4.
Ying Yong Sheng Tai Xue Bao ; 34(10): 2713-2722, 2023 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-37897278

RESUMO

Inner Mongolia grassland is rich in natural vegetation and mineral resources. Based on Landsat5/7/8 NDVI data, we used pixel binary model to invert vegetation coverage of Inner Mongolia grassland area, investigated the stability, spatial distribution, and future evolution trend of vegetation coverage by using Sen+MK and Hurst index, and analyzed the driving factors of the spatial differentiation of vegetation coverage by the optimal parameters-based geographical detector. The results showed that vegetation coverage of Inner Mongolia grassland showed an increasing trend from 2006 to 2020, and the overall spatial pattern was high in the east and low in the west, mainly with great fluctuation. The regions with slight or obvious improvement characteristics (64.8%) were much more than those with slight or severe degradation characteristics (23.2%). Compared with that in the past 15 years, the proportion of degraded vegetation in the future is expected to increase to 36.6%. The central part of Xilin Gol League and Wulanqab in the central grassland area, the western part of Hulunbuir and Erdos in the eastern grassland area, and Wuhai in the western grassland area were at the risk of degradation, which should be paid more attention. Precipitation was the dominant factor of spatial differentiation in Inner Mongolia grassland, while soil type, land use, and air temperature had the most significant synergistic effect.


Assuntos
Pradaria , Solo , Temperatura , China , Previsões , Ecossistema
5.
Org Lett ; 25(31): 5784-5789, 2023 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-37503958

RESUMO

Late-stage diversification of structurally complex peptides has enormous potential for drug discovery and molecular imaging. We report a simple, metal-free, late-stage reductive C2 alkylation of tryptophan and tryptophan-containing peptides using readily available 1,3-dithianes. This alkylation protocol has a wide substrate scope and an excellent tolerance for reactive functional groups.


Assuntos
Compostos Heterocíclicos , Triptofano , Triptofano/química , Peptídeos/química , Metais , Alquilação
6.
Org Lett ; 25(26): 4782-4786, 2023 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-37358213

RESUMO

Herein, we report a protocol for the stereoselective C-H alkenylation of five-membered heteroarenes including pyrroles (containing free NH pyrrole), thiophenes, and furans with 1,3-dithiane derivatives through dual 1,3-sulfur rearrangements. The site-selective and regioselective alkenylation of the five-membered heteroarenes proceeded in good yields via vinyl thionium ions to produce C2 or C5 Heck-type products, respectively.

7.
Org Lett ; 24(48): 8875-8879, 2022 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-36441568

RESUMO

We herein describe an accessible ligand-controlled nickel-catalyzed tandem isomerization/regiodivergent hydroheteroarylation of α-alkenes with a series of heteroarenes, wherein the NHC ligand of heteroleptic Ni(II) complexes of the type Ni(NHC)[P(OEt)3]Br2 displayed significant effects on regulation. In the presence of NaOtBu, Ni(IMes)[P(OEt)3]Br2 enables C═C bond isomerization of α-alkenes over up to four sp3 carbon atoms to afford branched products, while Ni(IPr*OMe)[P(OEt)3]Br2 greatly deactivates α-alkene isomerization and favors the formation of linear products.

8.
J Org Chem ; 87(21): 14930-14939, 2022 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-36259953

RESUMO

A simple and efficient method for structurally diverse symmetrical and unsymmetrical 3,3'- and 2,3'-bisindolylmethanes has been developed through a one-pot sequential reaction using 1,3-dithiane as the methylene source. The important AhR agonists ICZ and malassezin were synthesized with excellent efficiency by this straightforward approach.


Assuntos
Metano
9.
Org Lett ; 24(42): 7742-7746, 2022 10 28.
Artigo em Inglês | MEDLINE | ID: mdl-36255292

RESUMO

Methods for the modification of indole derivatives are powerful techniques in organic, medicinal, and biomolecular chemistry. Here, we report a protocol for the C-H alkenylation of N-H indoles with ß-chlorovinyl dithianes to furnish alkenyl indoles through dual 1,3-sulfur rearrangements. This alkenylation protocol could selectively prepare a variety of vinyl indoles in moderate to high yields with excellent functional group tolerance.


Assuntos
Indóis , Enxofre , Indóis/química , Catálise
10.
J Am Chem Soc ; 144(6): 2460-2467, 2022 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-35112837

RESUMO

A novel protocol is established for the long-standing challenge of stereoselective geminal bisglycosylations of saccharides. The merger of PPh3 as a traceless glycosidic leaving group and 1,2-boronate migration enables the simultaneous introduction of C-C and C-B bonds at the anomeric stereogenic center of furanoses and pyranoses. The power of this method is showcased by a set of site-selective modifications of glycosylation products for the construction of bioactive conjugates and skeletons. A scarce metal-free 1,1-difunctionalization process of alkenes is also concomitantly demonstrated.

11.
Huan Jing Ke Xue ; 42(11): 5180-5192, 2021 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-34708957

RESUMO

In recent years, fine particulate matter(PM2.5) and ozone(O3) have become the main air pollutants in cities in China. Volatile organic compounds(VOCs) are one of the important precursors of PM2.5, O3, and secondary organic aerosols. The establishment of VOCs emission inventory is therefore of great significance for controlling the amount of PM2.5 and O3. To date, the coefficient method has been used, which has error transmission of activity level, parameter and model, leading to the uncertainty of emission inventory. Multivariate uncertainty quantitative analysis of VOCs emission inventory provides an accurate alternative which has not been reported in China. The bottom-up method is adopted to collect the activity level of each enterprise. The variables of pollution control measures are obtained from surveys conducted with enterprises. The VOCs emission inventory of Qingdao from industrial source is established using an optimized coefficient method. The uncertainty of the VOCs inventory on the impact of univariate and multivariate variables is simulated by combining the Monte Carlo method(MC) with Latin hypercube sampling method(LHS). The results show that the total VOCs emissions were 44700 tons from industrial sources in 2019(unoptimized coefficient method:31100 tons).The rubber and plastic industries, metal products, and oil/coal/other fuel processing contributed more VOCs, which accounted for 40.26% of the total emissions. The uncertainty of multivariate simulation is higher than that of single variable. The uncertainty from process(-9.72%-230.51%) and solvent using source(-14.14%-122.77%) is significantly higher than uncertainty from combustion source(-15.62%-36.41%). The main sectors affecting the uncertainty of the VOCs inventory include:the chemical, papermaking, and textile industries(emission factors); metal, automobile manufacturing, and chemical industries(removal rate, facility operating rate); industries of petroleum processing and ferrous metal smelting(too few samples). VOCs emissions are mainly distributed in the east of the West Coast New district, north of Dazhu Mountain, south of Jimo district, north of Chengyang district, northeast of Jiaozhou district, built-up area of Pingdu district, and southeast of Laixi district.


Assuntos
Poluentes Atmosféricos , Ozônio , Compostos Orgânicos Voláteis , Poluentes Atmosféricos/análise , China , Monitoramento Ambiental , Método de Monte Carlo , Ozônio/análise , Incerteza , Compostos Orgânicos Voláteis/análise
12.
Zhonghua Nan Ke Xue ; 26(4): 331-334, 2020 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-33351300

RESUMO

OBJECTIVE: To explore and analyze the effect of liquid dressing in relieving pain and preventing incision adhesion after circumcision and its clinical application value. METHODS: Ninety male patients underwent circumcision in Hangzhou Third People's Hospital from September to November 2019, with the incision covered with liquid dressing + vaseline gauze (group A, n = 30), liquid dressing alone (group B, n = 30) or vaseline gauze only (group C, n = 30). At 2, 4 and 6 days after surgery, we compared the Visual Analogue Scale (VAS) pain intensity at dressing change, incision bleeding after dressing removal and incidence of postoperative complications among the three groups of patients. RESULTS: At 2, 4 and 6 days after surgery, the VAS pain score and incidence of incision bleeding were significantly lower in groups A and B than in C (P < 0.05). At 2 days, both the VAS pain score and incidence of incision bleeding were markedly decreased in group A as compared with those in group B (P < 0.05). At 4 and 6 days, the VAS pain score remained lower in group A than in B (P < 0.05), but the incidence rate of incision bleeding showed no significant difference between the two groups (P > 0.05). No statistically significant differences were observed in the incidence of postoperative complications among the three groups (P > 0.05). CONCLUSIONS: Liquid dressing can reduce pain intensity at dressing change, prevent incision adhesion and consequent dressing change-induced tearing and bleeding, and therefore promote incision healing after circumcision. Its combination with vaseline gauze can achieve an even better effect.


Assuntos
Bandagens/classificação , Circuncisão Masculina , Cicatrização , Humanos , Masculino , Dor/prevenção & controle , Medição da Dor
13.
J Agric Food Chem ; 67(32): 8986-8993, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31347835

RESUMO

Trehalose plays a crucial role in response to freezing stress in baker's yeast. MAL62, a gene involved in the adenosine diphosphoglucose-dependent trehalose synthesis pathway, can increase trehalose content. However, the difference between MAL62-related trehalose synthesis and traditional uridine diphosphoglucose-dependent trehalose synthesis is not well-understood. MAL62 overexpression showed less effect in enhancing intracellular trehalose compared to TPS1 overexpression. However, MAL62 overexpression elicited trehalose synthesis before fermentation with enhanced maltose metabolism and had a similar effect on cell viability after freezing. Furthermore, MAL62 and TPS1 overexpression in the NTH1 deletion background further strengthened freezing tolerance and improved leavening ability. Our results suggest that the enhancement in freezing tolerance by MAL62 overexpression may involve multiple pathways rather than simply enhancing trehalose synthesis. The results reveal valuable insights into the relationship between maltose metabolism and freezing tolerance and may help to develop better yeast strains for enhancing fermentation characteristics of frozen dough.


Assuntos
Glucosiltransferases/metabolismo , Maltose/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , alfa-Glucosidases/metabolismo , Farinha/análise , Farinha/microbiologia , Congelamento , Regulação Fúngica da Expressão Gênica , Glucosiltransferases/genética , Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Trealase/genética , Trealase/metabolismo , Trealose/metabolismo , alfa-Glucosidases/genética
14.
Org Lett ; 21(13): 5055-5058, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31247808

RESUMO

A facile regioselective switch for nickel-catalyzed hydroarylation of vinylarenes with benzothiazoles has been developed, which relies on the simple structural variation of novel Ni(II) complexes of the type Ni(NHC)[P(OR)3]Br2. Using magnesium turnings as the reductant, Ni(IMes)[P(OEt)3]Br2 afforded branched products, while Ni(IPr*OMe)[P(OEt)3]Br2 created steric demand to afford linear products. This work also provides a rare example of the rational design of heteroleptic Ni(II) complexes that display the required air stability, reactivity, and regioselectivity via synergism between NHC and phosphite ligands.

15.
Zhonghua Nan Ke Xue ; 25(6): 535-538, 2019 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-32223089

RESUMO

OBJECTIVE: To investigate the infection of reproductive Mycoplasma genitalium (MG) detected by real-time fluorescence constant-temperature simultaneous amplification and testing (SAT) of nucleic acid among patients present at the clinics of urology, gynecology or venereal diseases. METHODS: We retrospectively analyzed the clinical data on 5 711 patients with suspected genitourinary tract (GUT) infection present at the clinics of urology, gynecology or sexually transmitted diseases in Hangzhou Third People's Hospital, Shaoxing People's Hospital and General Hospital of Eastern Theater Command from January 2018 to December 2018. The patients were aged 16-73 (38.77 ± 11.32) years, 3 425 males and 2 286 females. We collected urine samples from 3 666, GUT secretion samples from 2 095, and both urine and GUT samples from 50 of the patients. Using the SAT technique, we detected the infections of MG, Ureaplasma urealyticum (UU), Chlamydia trachomatis (CT), and Neisseria gonorrhoeae (NG) in the patients. RESULTS: Of the 5 711 patients, 294 (5.15%) were found MG-positive, with a significantly higher positive rate in the males than in the females (5.96% ï¼»206/3 425ï¼½ vs 3.85% ï¼»88/2 286ï¼½, P < 0.05). The laboratory results with the urine and GUT secretion samples from 50 of the cases showed a consistency rate of 100%. Simple MG infection accounted for 52.04% in the 294 MG-positive cases, 63.11% in the 206 MG-positive males, and 26.13% in the 88 females, with a significantly higher positive rate in the males than in the females (P < 0.05). MG combined with UU infection had the highest rate among the mixed infections in both the males and females and in those aged ≤20 years, even higher in the females than in the males (P < 0.05) and in the ≤20-year-old males than in the ≤20-year-old females (8.65% ï¼»9/104ï¼½ vs 5.13% ï¼»4/78ï¼½, P < 0.05). There were statistically significant differences in the MG-positive rate among different age groups (χ2 = 32.74, P < 0.05). CONCLUSIONS: Among patients with suspected GUT infection, the MG-positive rate is higher in men than in women, with MG + UU-positive as the most common mixed infection, and it decreases with the increase of age. The results of SAT of urine and GUT secretion have a high consistency rate.


Assuntos
Infecções por Mycoplasma/diagnóstico , Técnicas de Amplificação de Ácido Nucleico , Infecções Urinárias/diagnóstico , Adolescente , Adulto , Idoso , China , Chlamydia trachomatis , Coinfecção/diagnóstico , Feminino , Fluorescência , Humanos , Masculino , Pessoa de Meia-Idade , Mycoplasma genitalium , Neisseria gonorrhoeae , Estudos Retrospectivos , Temperatura , Ureaplasma urealyticum , Infecções Urinárias/microbiologia , Adulto Jovem
16.
Behav Brain Res ; 291: 12-19, 2015 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-25958231

RESUMO

Thymol, a bioactive monoterpene isolated from Thymus vulgaris, has displayed inspiring neuroprotective properties. The present study was designed to evaluate the antidepressant-like effects of thymol on a chronic unpredictable mild stress (CUMS) model of depression in mice and explore the underlying mechanisms. It was observed that thymol treatment (15 mg/kg and 30 mg/kg) significantly reversed the decrease of sucrose consumption, the loss of body weight, the reduction of immobile time in the tail suspension tests (TST) and forced swimming tests (FST) induced by CUMS paradigm. The levels of norepinephrine (NE) and serotonin (5-HT) in the hippocampus decreased in the CUMS-treated mice. Chronic treatments with thymol significantly restored the CUMS-induced alterations of monoamine neurotransmitters in the hippocampus. Our results further demonstrated that thymol administration negatively regulated the induction of proinflammatory cytokines including interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α in CUMS mice. Furthermore, thymol inhibited the activation of nod-like receptor protein 3 (NLRP3) inflammasome and its adaptor, and subsequently decreased the expression of caspase-1. In sum, our findings suggested that thymol played a potential antidepressant role in CUMS mice model through up-regulating the levels of central neurotransmitters and inhibiting the expressions of proinflammatory cytokines, which might provide potential for thymol in the light of opening up new therapeutic avenues for depression.


Assuntos
Antidepressivos/farmacologia , Transtorno Depressivo/tratamento farmacológico , Transtorno Depressivo/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Timol/farmacologia , Animais , Proteínas de Transporte/metabolismo , Caspase 1/metabolismo , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Masculino , Camundongos Endogâmicos ICR , Proteína 3 que Contém Domínio de Pirina da Família NLR , Norepinefrina/metabolismo , Distribuição Aleatória , Serotonina/metabolismo , Estresse Psicológico , Fator de Necrose Tumoral alfa/metabolismo
17.
Chin J Nat Med ; 12(10): 753-9, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25443368

RESUMO

Perilla frutescens (Perilla leaf), a garnishing vegetable in East Asian countries, as well as a plant-based medicine, has been used for centuries to treat various conditions, including depression. Several studies have demonstrated that the essential oil of P. frutescens (EOPF) attenuated the depressive-like behavior in mice. The present study was designed to test the anti-depressant effects of EOPF and the possible mechanisms in an chronic, unpredictable, mild stress (CUMS)-induced mouse model. With the exposure to stressor once daily for five consecutive weeks, EOPF (3, 6, and 9 mg·kg(-1)) and a positive control drug fluoxetine (20 mg·kg(-1)) were administered through gastric intubation to mice once daily for three consecutive weeks from the 3(rd) week. Open-field test, sucrose consumption test, tail suspension test (TST), and forced swimming test (FST) were used to evaluate the behavioral activity. The contents of 5-hydroxytryptamine (5-HT) and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), in mouse hippocampus were determined by HPLC-ECD. Serum interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α levels were evaluated by enzyme-linked immunosorbent assay (ELISA). The results showed that CUMS significantly decreased the levels of 5-HT and 5-HIAA in the hippocampus, with an increase in plasma IL-6, IL-1ß, and TNF-α levels. CUMS also reduced open-field activity, sucrose consumption, as well as increased immobility duration in FST and TST. EOPF administration could effectively reverse the alterations in the concentrations of 5-HT and 5-HIAA; reduce the IL-6, IL-1ß, and TNF-α levels. Moreover, EOPF could effectively reverse alterations in immobility duration, sucrose consumption, and open-field activity. However, the effect was not dose-dependent. In conclusion, EOPF administration exhibited significant antidepressant-like effects in mice with CUMS-induced depression. The antidepressant activity of EOPF might be related to the relation between alteration of serotonergic responses and anti-inflammatory effects.


Assuntos
Antidepressivos/administração & dosagem , Depressão/tratamento farmacológico , Óleos Voláteis/administração & dosagem , Perilla frutescens/química , Óleos de Plantas/administração & dosagem , Animais , Comportamento Animal/efeitos dos fármacos , Doença Crônica/terapia , Citocinas/sangue , Depressão/sangue , Depressão/fisiopatologia , Depressão/psicologia , Modelos Animais de Doenças , Humanos , Masculino , Camundongos , Camundongos Endogâmicos ICR , Estresse Fisiológico/efeitos dos fármacos
18.
Pharmacol Biochem Behav ; 116: 1-8, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24201050

RESUMO

Perillaldehyde (PAH), a major component of essential oil of Perilla Frutescens, has antidepressant-like effects and anti-inflammatory effects. The present study was designed to determine whether PAH is effective in treating lipopolysaccharide (LPS)-induced depression-like behavior in mice and to explore the possible mechanism between its antidepressant-like effect and anti-inflammatory activity. PAH (60 and 120 mg/kg) and fluoxetine (20mg/kg) were administered intragastrically once daily for 7 consecutive days. In the 7th day, LPS (0.5mg/kg) was injected intraperitoneally 30 min after drug administration. Blood samples were collected 90 min after LPS injection to evaluate serum interleukin (IL)-6 and tumor necrosis factor (TNF)-α levels by enzyme-linked immunosorbent assay (ELISA). Behavioral tests were measured 24h after LPS injection. After the behavioral tests the prefrontal cortex was rapidly dissected from the brain of the sacrificed mice, then the 5-hydroxytryptamine (5-HT) and norepinephrine (NE) levels in prefrontal cortex were determined by HPLC-MS, and IL-6 and TNF-α mRNA expression was measured using quantitative real-time PCR. Our results showed that a single administration of LPS significantly increased the levels of TNF-α and IL-6 in both the serum and the prefrontal cortex and decreased 5-HT and NE levels in the prefrontal cortex in mice. Pretreatment with fluoxetine (20mg/kg) or PAH (60 and 120 mg/kg) could effectively reverse the alterations in the concentrations of 5-HT and NE, and attenuate LPS-induced increases in TNF-α and IL-6 levels. Besides, LPS administration increased the immobility time in tail suspension test (TST) and forced swimming test (FST) without affecting spontaneous locomotor activity. Fluoxetine (20mg/kg) or PAH (60 and 120 mg/kg) significantly shortened LPS-induced increases of immobility time in both TST and FST. In conclusion, PAH exhibited significant antidepressant-like effects in mice with LPS-induced depression. The antidepressant activity of PAH might be related to the alteration of monoaminergic responses and the anti-inflammatory effects.


Assuntos
Citocinas/sangue , Depressão/tratamento farmacológico , Lipopolissacarídeos/administração & dosagem , Monoterpenos/farmacologia , Animais , Sequência de Bases , Primers do DNA , Masculino , Camundongos , Camundongos Endogâmicos ICR , Monoterpenos/uso terapêutico , Reação em Cadeia da Polimerase em Tempo Real
19.
Huan Jing Ke Xue ; 31(12): 2835-43, 2010 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-21360869

RESUMO

33 total suspended particle samples and 7 size-segregated particle samples were collected over the East China Sea from Nov. to Dec., 2006, Feb. to Mar., 2007 and May. to Jun., 2008. Concentrations of ammonium, nitrate and nitrite in aerosols were measured to investigate their seasonal variation and size distribution. The concentrations of ammonium in aerosols ranged from 2.6 to 646.9 nmol x m(-3) ,with the higher values observed in winter and spring, and the lower values in summer. Nitrate concentrations were from 5.5 to 281.5 nmol x m(-3), presenting the seasonal trend of winter > spring approximately summer. The concentrations of nitrite were very low, less than 0.5 nmol x m(-3). The relative contributions of nitrogen species to total nitrogen varied seasonally in some extent. The contribution of nitrate was comparable with that of ammonium in winter, while the contribution of ammonium was the predominant in spring and summer. The size distribution of nitrate presented clear monthly changes. Most of nitrate existed in the fine particles less than 2.1 microm in Nov. to Dec., and it predominated in the coarse particles with the size of 1.1-4.7 microm and 2.1-7.0 microm, respectively, in Feb. to Mar. and May. to Jun. The size distributions of ammonium in different months were similar, with one peak presenting in the < 1.1 microm fine particles. The air mass back trajectories analysis indicated that the distributions of inorganic nitrogen in aerosols were significantly influenced by the sources and transport pathways of air mass. Both high nitrogen concentration per unit atmospheric volume (nmol x m(-3)) and per unit mass particle (micromol x g(-1)) occurred when the air mass passed over severe pollution region. Both low concentration in atmosphere and particle occurred when the air mass came from clean marine atmosphere. Lower concentration in atmosphere and higher concentration in particle occurred when the air mass originated from the continent and transported long distances over the sea.


Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Atmosfera/análise , Nitrogênio/química , China , Monitoramento Ambiental , Nitratos/análise , Nitritos/análise , Nitrogênio/análise , Oceanos e Mares , Compostos Orgânicos/análise , Compostos Orgânicos/química , Tamanho da Partícula , Compostos de Amônio Quaternário/análise , Estações do Ano
20.
J Phys Chem B ; 113(38): 12623-7, 2009 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-19719096

RESUMO

Nanoporous thin films fabricated by both a core-shell-shaped organic-inorganic hybrid sphere (octa(2,4-dinitrophenyl)silsesquioxane, ODNPSQ) and a four-leg-numbered surfactant (polyoxyethylene sorbitan monolaurate, Tween-20) for porogens in a higher molecular weight precursor (polyphenylsilsesquioxane, PPSQ) were characterized, respectively, by grazing incidence small-angle X-ray scattering (GISAXS), and the measured 2D GISAXS profiles were analyzed quantitatively by using a GISAXS formula based on the distorted wave Born approximation (DWBA). The fitted 2D GISAXS data show that the PPSQ porous thin films imprinted with ODNPSQ porogen exhibit sphere-shaped closed pores with the average pore size within a range of 1.18-3.12 nm and pore size distribution widths about 3.0 nm when the porogen loadings increase from 10 to 40 wt % and those imprinted with Tween-20 porogen give out an average pore size of 1.07-1.29 nm and pore size distribution widths about 2.0 nm with the porogen loading varying from 5 to 30 wt %. The nanoporous dielectric thin films imprinted with ODNPSQ porogen show a reducing to the molecular aggregation of porogens and significant antiphase separation behavior in the cross-linked matrix.


Assuntos
Membranas Artificiais , Nanoestruturas , Espalhamento a Baixo Ângulo , Silicatos/química , Porosidade , Propriedades de Superfície , Raios X
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