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1.
Soft Matter ; 19(10): 1913-1929, 2023 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-36804758

RESUMO

The incorporation of room temperature ionic liquids (ILs) into dielectric elastomer composites is currently generating great interest due to their potential applications in soft actuators and optical-related devices. Experiments have shown that the electrical properties of IL enhanced soft composites (ILESCs) are dependent on AC (alternating current) frequency of the electrical loading. This current work helps develop a mixed micromechanical model with the incorporation of an electric double layer (EDL) to predict the electrical properties of the ILESCs while revealing the physical mechanisms (including crowding and overscreening structures, percolation thresholds, interfacial tunneling, Maxwell-Wagner-Sillars polarization) that underpin the phenomena. Particularly, Bazant-Storey-Kornyshev (BSK) phenomenological theory is integrated into the EDL surface diffusion model for the first time to evaluate the influence of crowding and overscreening effects. The results show excellent agreement with experimental data of IL enhanced PDMS composites over the frequency range from 1 Hz to 10 GHz. Parametric analysis from the perspective of designing is conducted to explore the methods for optimization of ILESCs with high dielectric constants and frequency-dependent stability. It is found that an IL with a smaller size and aspect ratio increases the dielectric constant of the ILESCs more significantly below the interface relaxation frequency. Increasing the surface charge density of the matrix and using ILs delay the frequency-facilitated dielectric response, which is beneficial to maintain the dielectric stability of the ILESCs.

2.
J Environ Sci (China) ; 132: 71-82, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37336611

RESUMO

This study investigated the transformations of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in rhizosphere soils and adaptive responses of rhizobacterial community under the real field conditions during four growth stages (e.g., greening, tillering, heading, and maturity) of early rice (Zhongjiazao 17) and late rice (Zhongyou 9918) in Jiangshe village (JSV) and Yangji village (YJV). Results showed that rhizosphere soils of YJV were mildly polluted by Cd and PAHs compared to that of JSV. The relative abundance of bioavailable Cd (bio-Cd) and bioavailable As (bio-As) in rhizosphere soil increased before the heading stage but decreased at the subsequent growth stage, but the content of ΣPAHs in rhizosphere soil decreased gradually during whole growth period. The dominant rhizobacteria genera at YJV (e.g., Bacillus, Massilia, Sphingomonas, and Geobacter) increased at an abundance level from the tillering to heading stage. Rhizobacteria interacted with the above co-pollutant more intensely at the tillering and heading stage, where genes involved in HM-resistance and PAH-degradation appeared to have a significant enhancement. The contents of bio-Cd and bio-As in rhizosphere soil of early rice were higher than that of late rice at each growth stage, especially at the heading stage. Bio-Cd, ΣPAHs, and organic matter were key factors influencing the community structure of rhizobacteria. Results of this study provide valuable insights about the interactions between HM-PAH co-pollutant and rhizobacterial community under real field conditions and thus develop in-situ rhizosphere remediation techniques for contaminated paddy fields.


Assuntos
Poluentes Ambientais , Metais Pesados , Oryza , Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Hidrocarbonetos Policíclicos Aromáticos/análise , Oryza/química , Solo/química , Cádmio/metabolismo , Rizosfera , Metais Pesados/análise , Poluentes Ambientais/metabolismo , Poluentes do Solo/análise
3.
Small ; 18(12): e2107106, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35088934

RESUMO

Additives are often used to adjust the morphology of the active layer to improve the performance of organic solar cells (OSCs). Here, taking typical high-efficiency non-fullerene systems as examples, the effect of the additive on the device performance in non-fullerene OSCs is systematically investigated. Surprisingly, an unpresented VOC change is observed in the opposite direction of the two typical systems (PM6:Y6 and PTB7-Th: ITIC) appearing after the incorporation of the additive DIO, which can be affected by the morphological differences as indicated by the several morphological studies. The bewildering VOC change caused by the additive in different material systems is supposed to originate from the different energy level variations as verified by the energy level studies. Molecular dynamic (MD) and density functional theory (DFT) calculations are also included to get an insight into the dynamic of the additive-induced morphological differences that are supposed to contribute to the energy level changes. Combining a series of morphological and energic studies as well as the theoretical calculations, the origin of unforeseeable VOC changes caused by additives in non-fullerene OSCs is clarified, and provides in-depth insights into the effects of additives on device performance.

4.
Langmuir ; 37(14): 4347-4354, 2021 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-33797928

RESUMO

In this article combining density functional theory (DFT) calculations and corresponding experimental measurements, the adsorption behaviors and working mechanism of the alcohol-soluble ionic organic interlayer on different electrode substrates were studied. The results suggest that, when the ionic organic bipyridine salt interlayer (FPyBr) is adsorbed on the Ag surface, Br- will break away from molecule chains and form new chemical bonds with the Ag substrate, as confirmed by both the X-ray photoelectron spectroscopy (XPS) study and DFT study for the first time. Charges are further found to transfer to the Ag substrate from the new interlayer molecular structure without Br-, resulting in adsorption dipoles directed from Ag to the interlayer. Moreover, the direction of the intrinsic dipole of the molecule itself on the Ag substrate is also verified, which is the same as that of the adsorption dipole. Subsequently, the superposition of the two dipoles results in a large reduction of the Ag substrate work function. In addition, the dipole formation mechanism of the interlayer on the ITO surface was also studied. The change in the work function of the ITO substrate by this interlayer is found to be smaller than that of Ag as confirmed by both a DFT study and scanning Kelvin probe microscopy (SKPM) results, which is mainly due to the reversed direction of the molecular intrinsic dipole with respect to the interfacial dipole. The worst device performance of organic solar cells based on the ITO-FPyBr substrate is considered to be one of the consequences of the feature. The findings here are of great importance for the study of the mechanism of the ionic organic interlayer in organic electronic devices, providing insightful understandings on how to further improve the material and device performance.

5.
Int J Behav Nutr Phys Act ; 18(1): 21, 2021 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-33536027

RESUMO

BACKGROUND: Ultra-processed foods have now become dominant in the global food system. Whether their consumption is associated with cardiovascular mortality remains controversial. Moreover, data on ultra-processed foods and cardiovascular outcomes are scarce in the US population. We aimed to examine the association of ultra-processed food consumption with cardiovascular mortality in a US population. METHODS: A population-based cohort of 91,891 participants was identified from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Dietary data were collected through a validated 137-item food frequency questionnaire. Ultra-processed foods were defined by the NOVA classification. Cox regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for cardiovascular mortality. Restricted cubic spline regression was used to test nonlinearity. Subgroup analyses were conducted to identify the potential effect modifiers. RESULTS: After an average follow-up of 13.5 years (1,236,049.2 person-years), 5490 cardiovascular deaths were documented, including 3985 heart disease deaths and 1126 cerebrovascular deaths. In the fully adjusted model, participants in the highest vs. the lowest quintiles of ultra-processed food consumption had higher risks of death from cardiovascular disease (HRquintile 5 vs. 1, 1.50; 95% CI, 1.36-1.64) and heart disease (HRquintile 5 vs. 1, 1.68; 95% CI, 1.50-1.87) but not cerebrovascular disease (HRquintile 5 vs. 1, 0.94; 95% CI, 0.76-1.17). A nonlinear dose-response pattern was observed for overall cardiovascular and heart disease mortality (all Pnonlinearity < 0.05), with a threshold effect observed at ultra-processed food consumption of 2.4 servings/day and 2.3 servings/day, respectively; below the thresholds, no significant associations were observed for these two outcomes. Subgroup analyses showed that the increased risks of mortality from ultra-processed foods were significantly higher in women than in men (all Pinteraction < 0.05). CONCLUSIONS: High consumption of ultra-processed foods is associated with increased risks of overall cardiovascular and heart disease mortality. These harmful associations may be more pronounced in women. Our findings need to be confirmed in other populations and settings.


Assuntos
Doenças Cardiovasculares/mortalidade , Dieta/estatística & dados numéricos , Fast Foods/estatística & dados numéricos , Humanos , Estudos Prospectivos , Estados Unidos
6.
Anal Chem ; 92(20): 14145-14152, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32972132

RESUMO

Chemical reactions are the most important phenomena in chemistry. However, chemical reactions at buried solid/solid interfaces are very difficult to study in situ. In this research, the chemical reaction between two solid polymer materials, a nylon film and a maleic anhydride (MAH) grafted poly(ethylene-octene) (MAHgEO) sample, was directly analyzed at the buried nylon/MAHgEO interface at the molecular level in real time and in situ, using surface and interface sensitive sum-frequency generation (SFG) vibrational spectroscopy. Disappearance of nylon signals indicated a chemical reaction between amine and hydrolyzed amide groups of nylon and MAH groups on the MAHgEO at the buried interface. The appearance of SFG signals from reaction products was also observed at the buried nylon/MAHgEO interface. The mechanism of the observed interfacial reaction was further analyzed. Temperature-dependent SFG experiments were performed to measure the activation energy of the interfacial reaction, enabling a comparison with that reported for the bulk materials. The interfacial chemical reaction between nylon and MAHgEO greatly improved the adhesion of these dissimilar materials. The detailed analysis of a chemical reaction between two polymers at the polymer/polymer buried interface underscores the utility of SFG as a powerful analytical tool to build understanding of buried interfaces and to accelerate the design of interfacial structures with desired properties.

7.
Langmuir ; 36(38): 11349-11357, 2020 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-32870007

RESUMO

Nylon and maleic anhydride (MAH)-grafted polyolefin-based thin co-extruded multilayer films are widely used in packaging applications encountered in daily life. The molecular structure of the nylon/MAH-grafted polyolefin buried interface and molecular bonding between these two chemically dissimilar layers are thought to play an important role in achieving packaging structures with good adhesion. Here, the molecular bonds present at a nylon/maleic anhydride (MAH)-grafted polyethylene buried interface were systematically examined in situ for the first time using sum frequency generation (SFG) vibrational spectroscopy. The carbonyl stretching frequency region of the SFG spectra of a nylon/MAH-grafted polyethylene buried interface showed the presence of hydrolyzed MAH groups grafted to the polyethylene chain and very low levels of unreacted MAH enriched at the buried interface. The ability of SFG to detect these molecular species at the buried interface yields important understanding of the interfacial molecular structure and provides the basis for subsequent in situ studies of the bonding reaction between the grafted MAH and nylon directly at the interface. This understanding may guide the design of multilayer films with improved properties such as enhanced adhesion between polymer layers. The approach used in this study is general and is applicable to study the molecular characteristics of other buried interfaces of significance, such as buried interfaces involving polymers in solar cells, polymer semiconductors, and batteries. Nylon impact modification is another area of interest where the interaction between the MAH-grafted elastomer and the continuous phase of nylon is important.

8.
Ecotoxicol Environ Saf ; 184: 109655, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31525561

RESUMO

This study investigated the effects of Cupriavidus sp. strain Cd02-mediated increase on biosorption and bioprecipitation of Cd2+ during the 144-h cultivation time as well as evaluated effectivenesses of changing soil pH and bioavailability of cadmium after bioaugmentation of strain Cd02 into Cd-contaminated paddy soil for 15 days. Results showed that strain Cd02-induced pH increase of the culture medium (from 7.40 to 8.68) facilitated biosorption of Cd2+ on Cd02 cell surface (4.82 mg/mg) and extracellular bioprecipitation in form of cadmium carbonate (3.07 mg/mg). Also, the pH values of Cd-contaminated paddy soil increased by 1.41 units after strain Cd02 was applied for 15 days, which thereby promoted the decrease of exchangeable fraction of Cd2+ by 6.5% in the tested paddy soil. Meanwhile, strain Cd02 could prosperously live in paddy soils after bioaugmentation. These results suggest that strain Cd02 may be applicable for bioremediation of the heavy metal-contaminated soils by bioaugmentation.


Assuntos
Cádmio/análise , Carbonatos/análise , Cupriavidus/metabolismo , Poluentes do Solo/análise , Solo/química , Biodegradação Ambiental , Disponibilidade Biológica , Biomineralização , Cádmio/metabolismo , Carbonatos/metabolismo , Cupriavidus/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Oryza/crescimento & desenvolvimento , Poluentes do Solo/metabolismo
9.
Nanoscale ; 15(34): 14266, 2023 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-37584670

RESUMO

Correction for 'In situ synthesis of silver nanowire gel and its super-elastic composite foams' by Shu Huang et al., Nanoscale, 2020, 12, 19861-19869, https://doi.org/10.1039/D0NR03958F.

10.
J Econ Entomol ; 105(5): 1566-72, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23156151

RESUMO

The jasmine bud borer Trichophysetis cretacea (Butler) (Lepidoptera Crambidae) is an important agricultural pest of jasmine flowers Jasminum sambac in China. The extract from the pheromone gland of the female moth was analyzed by gas chromatography coupled to mass spectroscopy (GC-MS). (Z)-11-hexadecenyl acetate (Z11-16:Ac), (Z)-11-hexadecenal (Z11-16:Ald),and (Z)-11-hexadecenol (Z11-16:OH) were identified as the probable sex pheromone components. The electroantennogram (EAG) bioassay confirmed the results from the chemical analysis. Field bioassays conducted in the late summer and fall in Quanwei, Sichuan, China, showed that the synthetic chemical blend of Z11-16:Ac, Z11-16:Ald, and Z11-16:OH was highly attractive to male T. cretacea moths, and none of the three components was attractive by itself. All three components were necessary and the ratio of the three was critical. The highest number of male moths was captured when the ratio of Z11-16:Ac: Z11-16:Ald:Z11-16:OH was 10:10:1 at a dosage per lure of 200 microg Z11-16:Ac. The binary mixture of 200 microg Z11-16:Ac and 25 microg Z11-16:OH captured a number of Nymphicula mesorphna (10.3 +/- 4.4). The results indicate that traps with synthetic pheromone lures can be used to monitor jasmine bud borer populations in the field and potentially to control this pest.


Assuntos
Mariposas/efeitos dos fármacos , Percepção Olfatória , Feromônios/farmacologia , Atrativos Sexuais/farmacologia , Comportamento Sexual Animal , Acetatos/química , Acetatos/farmacologia , Aldeídos/química , Aldeídos/farmacologia , Animais , China , Fenômenos Eletrofisiológicos , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Masculino , Mariposas/fisiologia , Feromônios/química , Atrativos Sexuais/química
11.
Biomed Res Int ; 2022: 9015123, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36060139

RESUMO

Predicting the polyproline type II (PPII) helix structure is crucial important in many research areas, such as the protein folding mechanisms, the drug targets, and the protein functions. However, many existing PPII helix prediction algorithms encode the protein sequence information in a single way, which causes the insufficient learning of protein sequence feature information. To improve the protein sequence encoding performance, this paper proposes a BERT-based PPII helix structure prediction algorithm (BERT-PPII), which learns the protein sequence information based on the BERT model. The BERT model's CLS vector can fairly fuse sample's each amino acid residue information. Thus, we utilize the CLS vector as the global feature to represent the sample's global contextual information. As the interactions among the protein chains' local amino acid residues have an important influence on the formation of PPII helix, we utilize the CNN to extract local amino acid residues' features which can further enhance the information expression of protein sequence samples. In this paper, we fuse the CLS vectors with CNN local features to improve the performance of predicting PPII structure. Compared to the state-of-the-art PPIIPRED method, the experimental results on the unbalanced dataset show that the proposed method improves the accuracy value by 1% on the strict dataset and 2% on the less strict dataset. Correspondingly, the results on the balanced dataset show that the AUCs of the proposed method are 0.826 on the strict dataset and 0.785 on less strict datasets, respectively. For the independent test set, the proposed method has the AUC value of 0.827 on the strict dataset and 0.783 on the less strict dataset. The above experimental results have proved that the proposed BERT-PPII method can achieve a superior performance of predicting the PPII helix.


Assuntos
Aminoácidos , Peptídeos , Sequência de Aminoácidos , Peptídeos/química , Peptídeos/genética , Estrutura Secundária de Proteína
12.
Kaohsiung J Med Sci ; 38(6): 594-604, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35324061

RESUMO

Treatment of myocardial infarction (MI) remains a major challenge. The chemokine family plays an important role in cardiac injury, repair, and remodeling following MI, while stromal cell-derived factor-1 alpha (SDF-1α) is the most promising therapeutic target. This study aimed to increase SDF-1α expression using a novel gene delivery system and further explore its effect on MI treatment. In this study, two kinds of plasmids, human SDF-1α plasmid (phSDF-1α) and human SDF-1α- nuclear factor κB plasmid (phSDF-1α-NFκB), were constructed and loaded onto cationic microbubble carriers, and the plasmids were released into MI rabbits by ultrasound-targeted microbubble destruction. The transfection efficiency of SDF-1α and the degree of heart repair were further explored and compared. In the MI rabbit models, transfection with phSDF-1α-NFκB resulted in higher SDF-1α expression in peri-infarct area compared with transfection with phSDF-1α or no transfection. Upregulation of SDF-1α was shown beneficial to these MI rabbit models, as demonstrated with better recovery of cardiac function, greater perfusion of the myocardium, more neovascularization, smaller infarction size and thicker infarct wall 1 month after treatment. Ultrasound-targeted cationic microbubbles combined with the NFκB binding motif could increase SDF-1α gene transfection, which would play a protective role after MI.


Assuntos
Quimiocina CXCL12 , Infarto do Miocárdio , Animais , Quimiocina CXCL12/genética , Quimiocina CXCL12/metabolismo , Microbolhas , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/genética , Infarto do Miocárdio/terapia , Miocárdio/metabolismo , NF-kappa B/genética , Coelhos , Transfecção
13.
ACS Omega ; 7(43): 38613-38621, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36340129

RESUMO

A novel conjugated molecule (PBSON) based on a main chain composed of bis(dibenzothiophene-S,S-dioxide) fused cyclopentadiene and side chains containing amino groups is presented as an efficient cathode buffer material (CBM) for organic solar cells (OSCs). PBSON showed a deep highest occupied molecular orbital (HOMO) energy level of -6.01 eV, which was beneficial for building hole-blocking layers at the cathodes of OSCs. The energy bandgap of PBSON reached 3.17 eV, implying high transmittance to visible and near-infrared light, which meant PBSON should be suitable for the applications to most inverted OSCs. The scanning Kelvin probe microscopy measurement and theoretical calculation on the PBSON/cathode interfacial interaction proved the excellent work function-regulating abilities of PBSON for various cathodes, suggesting that PBSON could promote the formation of Ohmic contacts at the cathodes and thus improve the transport and collection of electron carriers for OSCs. The characterization of electron-only devices demonstrated the good electron-transporting performance of PBSON at the cathodes. In the conventional OSCs, it was hinted that PBSON might restrain the infiltrations of evaporated cathode atoms into the active films, consequently reducing the reverse leakage currents. As a result, PBSON was able to boost the power conversion efficiencies (PCEs) by 58.2 and 56.4% for both conventional and inverted OSCs of the typical PTB7:PC71BM system, respectively, as compared to the unadorned devices. In terms of the classical PTB7-Th:PC71BM system, substantial increases in PCEs could also be found with PBSON interlayers, which were 54.7 and 59.8% for the conventional device and inverted device, respectively. Therefore, PBSON is a kind of promising CBM for realizing both conventional and inverted OSCs of high performance.

14.
Nanomaterials (Basel) ; 11(12)2021 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-34947569

RESUMO

Due to their excellent combination of mechanical and physical properties, graphene and its derivatives as reinforcements have been drawing tremendous attention to the development of high-performance and multifunctional cement-based composites. This paper is mainly focused on reviewing existing studies on the three material properties (electrical, piezoresistive and electromagnetic) correlated to the multifunction of graphene reinforced cement composite materials (GRCCMs). Graphene fillers have demonstrated better reinforcing effects on the three material properties involved when compared to the other fillers, such as carbon fiber (CF), carbon nanotube (CNT) and glass fiber (GF). This can be attributed to the large specific surface area of graphene fillers, leading to improved hydration process, microstructures and interactions between the fillers and the cement matrix in the composites. Therefore, studies on using some widely adopted methods/techniques to characterize and investigate the hydration and microstructures of GRCCMs are reviewed and discussed. Since the types of graphene fillers and cement matrices and the preparation methods affect the filler dispersion and material properties, studies on these aspects are also briefly summarized and discussed. Based on the review, some challenges and research gaps for future research are identified. This review is envisaged to provide a comprehensive literature review and more insightful perspectives for research on developing multifunctional GRCCMs.

15.
Commun Chem ; 4(1): 150, 2021 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-36697810

RESUMO

One of the challenges for high-efficiency single-component-based photoredox catalysts is the low charge transfer and extraction due to the high recombination rate. Here, we demonstrate a strategy to precisely control the charge separation and transport efficiency of the catalytic host by introducing electron or hole extraction interlayers to improve the catalytic efficiency. We use simple and easily available non-conjugated polyelectrolytes (NCPs) (i.e., polyethyleneimine, PEI; poly(allylamine hydrochloride), PAH) to form interlayers, wherein such NCPs consist of the nonconjugated backbone with charge transporting functional groups. Taking CdS as examples, it is shown that although PEI and PAH are insulators and therefore do not have the ability to conduct electricity, they can form good electron or hole transport extraction layers due to the higher charge-transfer kinetics of pendant groups along the backbones, thereby greatly improving the charge transfer capability of CdS. Consequently, the resultant PEI-/PAH-functionalized nanocomposites exhibit significantly enhanced and versatile photoredox catalysis.

16.
World J Clin Cases ; 9(24): 7085-7091, 2021 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-34540963

RESUMO

BACKGROUND: Lymphangioleiomyomatosis (LAM) is a rare cystic lung disease characterized by the proliferation, metastasis, and infiltration of smooth muscle cells in the lung and other tissues, which can be associated with tuberous sclerosis complex (TSC). The disorder of TSC has a variable expression, and there is great phenotypic variability. CASE SUMMARY: A 32-year-old Chinese woman with a history of multiple renal angioleiomyolipoma presented with a productive cough persisting for over 2 wk. High-resolution chest computed tomography revealed interstitial changes, multiple pulmonary bullae, bilateral pulmonary nodules, and multiple fat density areas of the inferior mediastinum. Conventional and contrast ultrasonography revealed multiple high echogenic masses of the liver, kidneys, retroperitoneum, and inferior mediastinum. These masses were diagnosed as angiomyolipomas. Pathology through thoracoscopic lung biopsy confirmed LAM. Furthermore, high-throughput genome sequencing of peripheral blood DNA confirmed the presence of a heterozygous mutation, c.1831C>T (p.Arg611Trp), of the TSC2 gene. The patient was diagnosed with TSC-LAM. CONCLUSION: We highlight a rare case of TSC-LAM and the first report of a mediastinum lymphangioleiomyoma associated with TSC-LAM.

17.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 2): o295, 2010 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-21579729

RESUMO

The title compound, C(22)H(32)O(7), a natural ent-kaurane diterpenoid also referred to as Maoyecrystal F, was obtained from the medicinal plant Isodon nervosa. There are four rings with the expected cis and trans junctions. Cyclohexane ring A adopts a chair conformation, rings B and C adopt boat conformations, while the five-membered ring has an envelope conformation. The mol-ecules stack along the a axis in the crystal and are linked together by inter-molecular O-H⋯O hydrogen bonds.

18.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 2): o334, 2010 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-21579763

RESUMO

The title compound, C(20)H(30)O(6), a natural ent-kaurane diterpenoid, named nervosanin B, was obtained from the medicinal plant Isodon serra. It is composed of four rings with the expected trans and cis junctions. One of the six-membered rings is in a chair conformation, the other two are in boat conformations and the five-membered ring adopts an evenlope conformation. The mol-ecules stack along the a axis and are linked together by inter-molecular O-H⋯O hydrogen bonds. Two intramolecular O-H⋯O interactions also occur.

19.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 2): o359, 2010 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-21579784

RESUMO

The title compound, C(24)H(34)O(8), a natural ent-kaurane diterpenoid, is composed of four rings with the expected cis and trans junctions. The crystal structure is stabilized by inter-molecular O-H⋯O hydrogen bonds. In addition, an intra-molecular O-H⋯O hydrogen bond occurs.

20.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 4): o930, 2010 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-21580740

RESUMO

The title compound, C(21)H(30)O(6), a natural ent-kaurane diterpenoid, was obtained from the medicinal plant Isodon serra. The five rings in the mol-ecule exhibit the expected cis and trans junctions. The three six-membered rings adopt chair, twist-boat and boat conformations, while two five-membered rings adopt envelope conformations. There are two mol-ecules in the asymmetric unit, related by a non-crystallographic twofold screw axis; the main difference is in the different degrees of distortion of ring B. In the crystal, the mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds, forming chains along the b axis.

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