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1.
Plant Cell ; 29(6): 1440-1459, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28536145

RESUMO

This study investigates the role of volatile organic compounds in systemic acquired resistance (SAR), a salicylic acid (SA)-associated, broad-spectrum immune response in systemic, healthy tissues of locally infected plants. Gas chromatography coupled to mass spectrometry analyses of SAR-related emissions of wild-type and non-SAR-signal-producing mutant plants associated SAR with monoterpene emissions. Headspace exposure of Arabidopsis thaliana to a mixture of the bicyclic monoterpenes α-pinene and ß-pinene induced defense, accumulation of reactive oxygen species, and expression of SA- and SAR-related genes, including the SAR regulatory AZELAIC ACID INDUCED1 (AZI1) gene and three of its paralogs. Pinene-induced resistance was dependent on SA biosynthesis and signaling and on AZI1 Arabidopsis geranylgeranyl reductase1 mutants with reduced monoterpene biosynthesis were SAR-defective but mounted normal local resistance and methyl salicylate-induced defense responses, suggesting that monoterpenes act in parallel with SA The volatile emissions from SAR signal-emitting plants induced defense in neighboring plants, and this was associated with the presence of α-pinene, ß-pinene, and camphene in the emissions of the "sender" plants. Our data suggest that monoterpenes, particularly pinenes, promote SAR, acting through ROS and AZI1, and likely function as infochemicals in plant-to-plant signaling, thus allowing defense signal propagation between neighboring plants.


Assuntos
Arabidopsis/metabolismo , Monoterpenos/farmacologia , Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Monoterpenos Bicíclicos , Compostos Bicíclicos com Pontes/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/genética , Imunidade Inata/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Ácido Salicílico/farmacologia , Transdução de Sinais/efeitos dos fármacos
2.
Glob Chang Biol ; 26(3): 1908-1925, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31957145

RESUMO

Warming occurs in the Arctic twice as fast as the global average, which in turn leads to a large enhancement in terpenoid emissions from vegetation. Volatile terpenoids are the main class of biogenic volatile organic compounds (VOCs) that play crucial roles in atmospheric chemistry and climate. However, the biochemical mechanisms behind the temperature-dependent increase in VOC emissions from subarctic ecosystems are largely unexplored. Using 13 CO2 -labeling, we studied the origin of VOCs and the carbon (C) allocation under global warming in the soil-plant-atmosphere system of contrasting subarctic heath tundra vegetation communities characterized by dwarf shrubs of the genera Salix or Betula. The projected temperature rise of the subarctic summer by 5°C was realistically simulated in sophisticated climate chambers. VOC emissions strongly depended on the plant species composition of the heath tundra. Warming caused increased VOC emissions and significant changes in the pattern of volatiles toward more reactive hydrocarbons. The 13 C was incorporated to varying degrees in different monoterpene and sesquiterpene isomers. We found that de novo monoterpene biosynthesis contributed to 40%-44% (Salix) and 60%-68% (Betula) of total monoterpene emissions under the current climate, and that warming increased the contribution to 50%-58% (Salix) and 87%-95% (Betula). Analyses of above- and belowground 12/13 C showed shifts of C allocation in the plant-soil systems and negative effects of warming on C sequestration by lowering net ecosystem exchange of CO2 and increasing C loss as VOCs. This comprehensive analysis provides the scientific basis for mechanistically understanding the processes controlling terpenoid emissions, required for modeling VOC emissions from terrestrial ecosystems and predicting the future chemistry of the arctic atmosphere. By changing the chemical composition and loads of VOCs into the atmosphere, the current data indicate that global warming in the Arctic may have implications for regional and global climate and for the delicate tundra ecosystems.


Assuntos
Aquecimento Global , Compostos Orgânicos Voláteis , Regiões Árticas , Ecossistema , Tundra
3.
Proc Natl Acad Sci U S A ; 112(36): 11211-6, 2015 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-26294252

RESUMO

The chromosomal position of the centromere-specific histone H3 variant CENH3 (also called "CENP-A") is the assembly site for the kinetochore complex of active centromeres. Any error in transcription, translation, modification, or incorporation can affect the ability to assemble intact CENH3 chromatin and can cause centromere inactivation [Allshire RC, Karpen GH (2008) Nat Rev Genet 9 (12):923-937]. Here we show that a single-point amino acid exchange in the centromere-targeting domain of CENH3 leads to reduced centromere loading of CENH3 in barley, sugar beet, and Arabidopsis thaliana. Haploids were obtained after cenh3 L130F-complemented cenh3-null mutant plants were crossed with wild-type A. thaliana. In contrast, in a noncompeting situation (i.e., centromeres possessing only mutated or only wild-type CENH3), no uniparental chromosome elimination occurs during early embryogenesis. The high degree of evolutionary conservation of the identified mutation site offers promising opportunities for application in a wide range of crop species in which haploid technology is of interest.


Assuntos
Autoantígenos/genética , Centrômero/genética , Proteínas Cromossômicas não Histona/genética , Haploidia , Plantas/genética , Mutação Puntual , Arabidopsis/genética , Arabidopsis/metabolismo , Autoantígenos/metabolismo , Western Blotting , Centrômero/metabolismo , Proteína Centromérica A , Proteínas Cromossômicas não Histona/metabolismo , Genótipo , Histonas/genética , Hordeum/genética , Hordeum/metabolismo , Cinetocoros/metabolismo , Microscopia Eletrônica de Varredura , Microscopia de Fluorescência , Modelos Genéticos , Fenótipo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas/metabolismo , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sementes/genética , Sementes/metabolismo , Sementes/ultraestrutura
4.
Langmuir ; 33(22): 5555-5564, 2017 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-28260383

RESUMO

Fog-collecting meshes show a great potential in ensuring the availability of a supply of sustainable freshwater in certain arid regions. In most cases, the meshes are made of hydrophilic smooth fibers. Based on the study of plant surfaces, we analyzed the fog collection using various polyethylene terephthalate (PET) fibers with different cross sections and surface structures with the aim of developing optimized biomimetic fog collectors. Water droplet movement and the onset of dripping from fiber samples were compared. Fibers with round, oval, and rectangular cross sections with round edges showed higher fog-collection performance than those with other cross sections. However, other parameters, for example, width, surface structure, wettability, and so forth, also influenced the performance. The directional delivery of the collected fog droplets by wavy/v-shaped microgrooves on the surface of the fibers enhances the formation of a water film and their fog collection. A numerical simulation of the water droplet spreading behavior strongly supports these findings. Therefore, our study suggests the use of fibers with a round cross section, a microgrooved surface, and an optimized width for an efficient fog collection.

5.
Blood ; 116(22): 4646-56, 2010 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-20833976

RESUMO

Within the healthy population, there is substantial, heritable, and interindividual variability in the platelet response. We explored whether a proportion of this variability could be accounted for by interindividual variation in gene expression. Through a correlative analysis of genome-wide platelet RNA expression data from 37 subjects representing the normal range of platelet responsiveness within a cohort of 500 subjects, we identified 63 genes in which transcript levels correlated with variation in the platelet response to adenosine diphosphate and/or the collagen-mimetic peptide, cross-linked collagen-related peptide. Many of these encode proteins with no reported function in platelets. An association study of 6 of the 63 genes in 4235 cases and 6379 controls showed a putative association with myocardial infarction for COMMD7 (COMM domain-containing protein 7) and a major deviation from the null hypo thesis for LRRFIP1 [leucine-rich repeat (in FLII) interacting protein 1]. Morpholino-based silencing in Danio rerio identified a modest role for commd7 and a significant effect for lrrfip1 as positive regulators of thrombus formation. Proteomic analysis of human platelet LRRFIP1-interacting proteins indicated that LRRFIP1 functions as a component of the platelet cytoskeleton, where it interacts with the actin-remodeling proteins Flightless-1 and Drebrin. Taken together, these data reveal novel proteins regulating the platelet response.


Assuntos
Plaquetas/metabolismo , Perfilação da Expressão Gênica , Proteínas de Ligação a RNA/metabolismo , Animais , Inativação Gênica , Genótipo , Humanos , Ativação Plaquetária , Proteoma/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Trombose , Peixe-Zebra , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
6.
Beilstein J Nanotechnol ; 13: 944-957, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36161251

RESUMO

The cuticle with its superimposed epicuticular waxes represents the barrier of all aboveground parts of higher plant primary tissues. Epicuticular waxes have multiple effects on the interaction of plants with their living and non-living environment, whereby their shape, dimension, arrangement, and chemical composition play significant roles. Here, the ability of self-assembly of wax after isolation from the leaves was used to develop a small-scale wax-coated artificial leaf surface with the chemical composition and wettability of wheat (Triticum aestivum) leaves. By thermal evaporation of extracted plant waxes and adjustment of the evaporated wax amounts, the wettability and chemical character of the microstructure of the surface of wheat leaves were transferred onto a technical surface. For the use of these artificial leaves as a test system for biotic (e.g., germination of fungal pathogens) and non-biotic (e.g., applied surfactants) interactions on natural leaf surfaces, the chemical composition and the wetting behavior should be the same in both. Therefore, the morphology, chemistry, and wetting properties of natural and artificial surfaces with recrystallized wax structures were analyzed by scanning electron microscopy, gas chromatography-mass spectrometry, and by the determination of water contact angles, contact angle hysteresis, and tilting angles. Wheat leaves of different ages were covered exclusively with wax platelets. The extracted wheat wax was composed of alcohols, aldehydes, esters, and acids. The main component was 1-octacosanol. The waxes recrystallized as three-dimensional structures on the artificial surfaces. The three tested wetting parameters resembled the ones of the natural surface, providing an artificial surface with the chemical information of epicuticular waxes and the wetting properties of a natural leaf surface.

7.
Stud Health Technol Inform ; 294: 573-574, 2022 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-35612150

RESUMO

The complexity of emergency cases and the number of emergency patients have increased dramatically. Due to a reduced or even missing specialist medical staff in the emergency departments (EDs), medical knowledge is often used without professional supervision for the diagnosis. The result is a failure in diagnosis and treatment, even death in the worst case. Secondary: high expenditure of time and high costs. Using accurate patient data from the German national registry of the medical emergency departments (AKTIN-registry, Home - Notaufnahmeregister (aktin.org)), the most 20 frequent diagnoses were selected for creating explainable artificial intelligence (XAI) models as part of the ENSURE project (ENSURE (umg.eu)). 137.152 samples and 51 features (vital signs and symptoms) were analyzed. The XAI models achieved a mean area under the curve (AUC) one-vs-rest of 0.98 for logistic regression (LR) and 0.99 for the random forest (RF), and predictive accuracies of 0.927 (LR) and 0.99 (RF). Based on its grade of explainability and performance, the best model will be incorporated into a portable CDSS to improve diagnoses and outcomes of ED treatment and reduce cost. The CDSS will be tested in a clinical pilot study at EDs of selected hospitals in Germany.


Assuntos
Inteligência Artificial , Sistemas de Apoio a Decisões Clínicas , Área Sob a Curva , Humanos , Modelos Logísticos , Projetos Piloto
8.
Stud Health Technol Inform ; 289: 224-227, 2022 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-35062133

RESUMO

The development of clinical decision support systems (CDSS) is complex and requires user-centered planning of assistive interventions. Especially in the setting of emergency care requiring time-critical decisions and interventions, it is important to adapt a CDSS to the needs of the user in terms of acceptance, usability and utility. In the so-called ENSURE project, a user-centered approach was applied to develop the CDSS intervention. In the context of this paper, we present a path to the first mockup development for a CDSS interface by addressing Campbell's Five Rights within the CDSS workflow.


Assuntos
Sistemas de Apoio a Decisões Clínicas , Medicina de Emergência , Algoritmos , Fluxo de Trabalho
9.
Planta ; 234(6): 1267-74, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21785997

RESUMO

Some lichens have a super-hydrophobic upper surface, which repels water drops, keeping the surface dry but probably preventing water uptake. Spore ejection requires water and is most efficient just after rainfall. This study was carried out to investigate how super-hydrophobic lichens manage water uptake and repellence at their fruiting bodies, or podetia. Drops of water were placed onto separate podetia of Cladonia chlorophaea and observed using optical microscopy and cryo-scanning-electron microscopy (cryo-SEM) techniques to determine the structure of podetia and to visualise their interaction with water droplets. SEM and optical microscopy studies revealed that the surface of the podetia was constructed in a three-level structural hierarchy. By cryo-SEM of water-glycerol droplets placed on the upper part of the podetium, pinning of the droplet to specific, hydrophilic spots (pycnidia/apothecia) was observed. The results suggest a mechanism for water uptake, which is highly sophisticated, using surface wettability to generate a passive response to different types of precipitation in a manner similar to the Namib Desert beetle. This mechanism is likely to be found in other organisms as it offers passive but selective water control.


Assuntos
Líquens/fisiologia , Água/metabolismo , Molhabilidade , Microscopia Crioeletrônica , Carpóforos/fisiologia , Glicerol , Interações Hidrofóbicas e Hidrofílicas , Líquens/ultraestrutura , Microscopia Eletrônica de Varredura , Reprodutibilidade dos Testes , Esporos Fúngicos/fisiologia , Propriedades de Superfície , Reino Unido , Água/química
10.
Blood ; 113(19): e1-9, 2009 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-19228925

RESUMO

Hematopoiesis is a carefully controlled process that is regulated by complex networks of transcription factors that are, in part, controlled by signals resulting from ligand binding to cell-surface receptors. To further understand hematopoiesis, we have compared gene expression profiles of human erythroblasts, megakaryocytes, B cells, cytotoxic and helper T cells, natural killer cells, granulocytes, and monocytes using whole genome microarrays. A bioinformatics analysis of these data was performed focusing on transcription factors, immunoglobulin superfamily members, and lineage-specific transcripts. We observed that the numbers of lineage-specific genes varies by 2 orders of magnitude, ranging from 5 for cytotoxic T cells to 878 for granulocytes. In addition, we have identified novel coexpression patterns for key transcription factors involved in hematopoiesis (eg, GATA3-GFI1 and GATA2-KLF1). This study represents the most comprehensive analysis of gene expression in hematopoietic cells to date and has identified genes that play key roles in lineage commitment and cell function. The data, which are freely accessible, will be invaluable for future studies on hematopoiesis and the role of specific genes and will also aid the understanding of the recent genome-wide association studies.


Assuntos
Células da Medula Óssea/fisiologia , Diferenciação Celular/genética , Expressão Gênica , Atlas como Assunto , Linhagem da Célula , Células Cultivadas , Citometria de Fluxo , Perfilação da Expressão Gênica , Hematopoese , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , Fatores de Transcrição/metabolismo
11.
Blood ; 114(7): 1405-16, 2009 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-19429868

RESUMO

Platelet response to activation varies widely between individuals but shows interindividual consistency and strong heritability. The genetic basis of this variation has not been properly explored. We therefore systematically measured the effect on function of sequence variation in 97 candidate genes in the collagen and adenosine-diphosphate (ADP) signaling pathways. Resequencing of the genes in 48 European DNA samples nearly doubled the number of known single nucleotide polymorphisms (SNPs) and informed the selection of 1327 SNPs for genotyping in 500 healthy Northern European subjects with known platelet responses to collagen-related peptide (CRP-XL) and ADP. This identified 17 novel associations with platelet function (P < .005) accounting for approximately 46% of the variation in response. Further investigations with platelets of known genotype explored the mechanisms behind some of the associations. SNPs in PEAR1 associated with increased platelet response to CRP-XL and increased PEAR1 protein expression after platelet degranulation. The minor allele of a 3' untranslated region (UTR) SNP (rs2769668) in VAV3 was associated with higher protein expression (P = .03) and increased P-selectin exposure after ADP activation (P = .004). Furthermore the minor allele of the intronic SNP rs17786144 in ITPR1 modified Ca(2+) levels after activation with ADP (P < .004). These data provide novel insights into key hubs within platelet signaling networks.


Assuntos
Plaquetas/fisiologia , Degranulação Celular/genética , Regulação da Expressão Gênica/fisiologia , Ativação Plaquetária/genética , Locos de Características Quantitativas/fisiologia , Transdução de Sinais/genética , Regiões 3' não Traduzidas/genética , Regiões 3' não Traduzidas/metabolismo , Difosfato de Adenosina/genética , Difosfato de Adenosina/metabolismo , Alelos , Plaquetas/citologia , Colágeno/genética , Colágeno/metabolismo , Europa (Continente) , Feminino , Genômica , Genótipo , Humanos , Receptores de Inositol 1,4,5-Trifosfato/biossíntese , Receptores de Inositol 1,4,5-Trifosfato/genética , Masculino , Selectina-P/genética , Selectina-P/metabolismo , Polimorfismo de Nucleotídeo Único , Receptores de Superfície Celular/biossíntese , Receptores de Superfície Celular/genética , População Branca
12.
Reprod Biomed Online ; 22(2): 140-7, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21195027

RESUMO

Stem cell factor (SCF) plays a major role in haematopoiesis and spermatogenesis, and possibly female fertility. This study investigated the role of changes in SCF concentrations in 74 assisted conception patients. In group 1 (n=74) SCF concentration was assessed in serum and follicular fluid (FF) on the day of follicular puncture (FP) and compared in serum and FF in response to ovarian stimulation between low (n=25), moderate (n=26) and high (n=14) responders. In group 2 (n=30) serum for SCF assessment was collected throughout the menstrual cycle until gestation. SCF concentration related to the number of follicles in serum and in FF decreased from low to moderate and high responders (P<0.001); pregnancy rates were 20.0%, 34.6% and 50.1%, respectively (P=0.05). SCF in serum increased from stimulation days 6-8 to 9-11 and peaked on the day of human chorionic gonadotrophin injection (P=0.03). The SCF concentrations dropped slightly on the day of FP, increased significantly to the day of pregnancy confirmation and reached highest concentration (P=0.02) during gestation. SCF is involved in follicle development and may be a predictor of IVF outcome.


Assuntos
Fertilização in vitro , Fator de Células-Tronco/sangue , Biomarcadores/sangue , Gonadotropina Coriônica/farmacologia , Estradiol/sangue , Feminino , Líquido Folicular/metabolismo , Humanos , Ciclo Menstrual , Folículo Ovariano/efeitos dos fármacos , Indução da Ovulação , Gravidez , Taxa de Gravidez , Fator de Células-Tronco/metabolismo
13.
Beilstein J Nanotechnol ; 12: 939-949, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34497741

RESUMO

Eucalyptus trees and many plants from the grass family (Poaceae) and the heather family (Ericaceae) have a protective multifunctional wax coating on their surfaces made of branched ß-diketone tubules. ß-diketone tubules have a different size, shape, and chemical composition than the well-described nonacosanol tubules of the superhydrophobic leaves of lotus (Nelumbo nucifera). Until now the formation process of ß-diketone tubules is unknown. In this study, extracted wax of E. gunnii leaves and pure ß-diketone were recrystallized on two different artificial materials and analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to study their formation process. Both the wax mixture and pure ß-diketone formed tubules similar to those on E. gunnii leaves. Deviating platelet-shaped and layered structures not found on leaves were also formed, especially on areas with high mass accumulation. High-resolution AFM images of recrystallized ß-diketone tubules are presented for the first time. The data showed that ß-diketone tubules are formed by self-assembly and confirmed that ß-diketone is the shape-determining component for this type of tubules.

14.
Stud Health Technol Inform ; 281: 535-539, 2021 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-34042633

RESUMO

The PosiThera project focuses on the management of chronic wounds, which is multi-professional and multi-disciplinary. For this context, a software prototype was developed in the project, which is intended to support medical and nursing staff with the assistance of artificial intelligence. In accordance with the user-centred design, national workshops were held at the beginning of the project with the involvement of domain experts in wound care in order to identify requirements and use cases of IT systems in wound care, with a focus on AI. In this study, the focus was on involving nursing and nursing science staff in testing the software prototype to gain insights into its functionality and usability. The overarching goal of the iterative testing and adaptation process is to further develop the prototype in a way that is close to care.


Assuntos
Sistemas de Apoio a Decisões Clínicas , Inteligência Artificial , Humanos , Motivação , Software
15.
Stud Health Technol Inform ; 270: 607-612, 2020 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-32570455

RESUMO

The access to data in healthcare is an enabler for the implementation of clinical decision support systems (CDSS) in practice. The usage of CDSS aims to be of efficient assistance to healthcare providers. The aim of the BMBF project "PosiThera", is to support the involved professions in the treatment process of chronic wounds. In this study we implemented the formalized knowledge of chronic wound diagnosis into two different knowledge base approaches, the HL7 Arden Syntax and a Petri net approach. The motivating factor behind our study was to use both approaches for the implementation of the projects knowledge base and to compare the results. We implemented the formalized knowledge successfully in both approaches. The results of our comparison showed similarities and differences of the Arden Syntax and the Petri net approach, which might support the evolution of both approaches in the future.


Assuntos
Sistemas de Apoio a Decisões Clínicas , Doença Crônica , Humanos , Bases de Conhecimento , Linguagens de Programação
16.
Radiother Oncol ; 90(2): 265-72, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18804300

RESUMO

PURPOSE: Individual radiosensitivity as measured with in vitro irradiated lymphocytes using metaphase analysis can predict the risk of normal tissue effects after radiotherapy. This parameter is considered to be primarily determined by the cellular repair capacity of DNA double-strand breaks (DSBs). It is now tested to which extent this capacity also depends on homologous recombination (HR), which is a pathway available when cells are in S/G2 phase. METHODS: Experiments were performed with CHO K1 cells, in which HR was suppressed via knock-down of RAD51 using RNA interference (RNAi). RAD51 was measured via western and foci formation, cell survival by colony forming, DSBs by gammaH2AX foci formation, and chromosomal damage using PCC, G0 or G2 assay. RESULTS: In quiescent G1 cells DSB repair is completed 6h after irradiation. But there is still a substantial fraction of non-repaired DSBs. Most of these DSBs are repaired when G1 cells are stimulated into cell cycle. Suppression of HR by down-regulation of RAD51 did not affect this repair. In contrast, repair was inhibited when cells were irradiated in late S/G2. In line with these data down-regulation of HR did affect survival of cells irradiated in late S/G2, but not in G1. CONCLUSIONS: Individual radiosensitivity as measured for G0/1 cells using metaphase analysis does not depend on homologous recombination.


Assuntos
Quebras de DNA de Cadeia Dupla/efeitos da radiação , Tolerância a Radiação/genética , Recombinação Genética , Animais , Células CHO , Ciclo Celular/efeitos da radiação , Linhagem Celular , Aberrações Cromossômicas/efeitos da radiação , Cricetinae , Cricetulus , Reparo do DNA , Fase G2/efeitos da radiação , Histonas/metabolismo , Rad51 Recombinase/metabolismo
17.
Langmuir ; 25(24): 14116-20, 2009 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-19634871

RESUMO

More than 400 million years of evolution of land plants led to a high diversity of adapted surface structures. Superhydrophobic biological surfaces are of special interest for the development of biomimetic materials for self-cleaning, drag reduction, and energy conservation. The key innovation in superhydrophobic biological surfaces is hierarchical sculpturing. In plants, a hydrophobic wax coating creates water-repelling surfaces that in combination with two or more levels of sculpturing leads to superhydrophobicity. Hierarchical structuring is of special interest for technical "biomimetic" materials with low adhesion and self-cleaning properties. Here we introduce hierarchical surface sculptures of plants with up to six levels. The article gives an overview of the composition of hierarchical surfaces for superhydrophobicity and their use as models for the development of artificial self-cleaning or drag-reducing surfaces.


Assuntos
Materiais Biomiméticos/química , Interações Hidrofóbicas e Hidrofílicas , Folhas de Planta/fisiologia , Biomimética/métodos , Propriedades de Superfície
18.
Langmuir ; 25(22): 13077-83, 2009 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-19899819

RESUMO

The contact area between liquids and solid surfaces plays the crucial role in the wetting and self-cleaning properties of surfaces. In this study, we have developed a cryo-preparation method to visualize the contact area between liquids and superhydrophobic biological surfaces by scanning electron microscopy. Aqueous liquids that do not crystallize during freezing, such as glycerol and phosphoric acid, were used. First, the samples in contact with the liquid droplets were cooled with liquid nitrogen. After this, the droplets were separated and the contact areas on the frozen droplets were visualized by scanning electron microscopy. The contact areas of droplets on various biological and artificial surfaces with microstructure, nanostructure, and hierarchical structures are shown in detail. It could be shown that spaces between nanostructures were not penetrated by the droplet, which rested only on top of the structures. Measurements of the contact areas showed the largest reduction in the solid-liquid contact area on hierarchically structured leaf surfaces. On these surfaces, the droplets are in the "Cassie state" at both levels of surface structuring. On plant surfaces, the varying height of the epidermal cells and the surface relief caused considerable variations in the contact between droplet and surface. The examples demonstrate that this new approach provides detailed insights into the wetting behavior of surfaces in the Cassie state with partial contact with the liquid.


Assuntos
Microscopia Crioeletrônica/métodos , Microscopia Eletrônica de Varredura/métodos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Nanotecnologia/métodos , Interações Hidrofóbicas e Hidrofílicas , Propriedades de Superfície
19.
J Colloid Interface Sci ; 544: 172-177, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30836259

RESUMO

A tight connection of scattering to thermodynamic models is missing for clay systems. A new approach called "locally columnar model" gives an attempt for making this connection. The scattering model assumes an up-lining of clay particles with strong paracrystalline order and refers to a chemical potential/distance dependence. The thermodynamic model assumes a bidisperse distance distribution and gives input to the scattering model. Experimentally, polymer/clay systems with many molecular polymer masses were studied showing all very similar scattering curves. While the dominating bulk phase shows only the same weak tendency to stack formation for all molecular polymer masses, one coexisting phase with stronger stack formation was identified. The latter sample was used to determine the thickness of the clay platelets with adsorbed polymer that was then used to model the dominating bulk phase. The comparisons to the theory revealed that (a) most polymers are tightly bound to the clay, and (b) an agreement between the modeling and the theory was achieved. The main result of the experiments is the fraction of free polymers of 1:2400 that are not tightly bound to the clay particles.

20.
Micron ; 39(7): 759-72, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18187332

RESUMO

Plant surfaces are the interfaces of the organisms with respect to their environment. In the micro-dimension they show an enormous variety of functional three-dimensional structures. Their materials and structures developed over millions of years by evolutionary processes in which their functionality has been proven and selected by environmental pressures. As a result, nature developed highly functional materials with several amazing properties like superhydrophobicity and superhydrophilicity. These functional structures are built up by a complex biopolymer called cuticle. The cuticle is mainly composed of a three-dimensional network of cutin, and integrated and superimposed lipids called "waxes". Superimposed waxes are also called "epicuticular waxes". Epicuticular waxes often form two- and three-dimensional structures, in dimensions between hundreds of nanometers and some micrometers, which influence the wettability, self-cleaning behaviour and the light reflection at the cuticle interface. This review gives a brief introduction into the functions of the plant epicuticular waxes and summarises the current knowledge about their morphologies, crystal structures, growth by self-assembly and provides an overview about the microscopy and preparation techniques for their analysis.


Assuntos
Folhas de Planta/metabolismo , Ceras/química , Ceras/metabolismo , Cristalização , Interações Hidrofóbicas e Hidrofílicas , Epiderme Vegetal/química , Epiderme Vegetal/metabolismo , Folhas de Planta/ultraestrutura , Plantas/metabolismo
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