ScienceOpen research最新文献_第2页

Formation of nickel–iron meteorites by chemical fluid transport 镍铁陨石的化学流体输运形成

ScienceOpen research Pub Date : 2017-10-18 DOI: 10.14293/S2199-1006.1.SOR-EARTH.A2TIA5.V2

W. Schrön

{"title":"Formation of nickel–iron meteorites by chemical fluid transport","authors":"W. Schrön","doi":"10.14293/S2199-1006.1.SOR-EARTH.A2TIA5.V2","DOIUrl":"https://doi.org/10.14293/S2199-1006.1.SOR-EARTH.A2TIA5.V2","url":null,"abstract":"The deposition of solid material from the gas phase via chemical vapor transport (CVT) is a well-known process of industrial and geochemical relevance. There is strong evidence that this type of thermodynamically driven chemical transport reaction plays a significant role in certain natural processes. This article presents detailed evidence that CVT is a highly plausible mechanism for the formation of iron meteorites. In this study, naturally occurring CVT is referred to as “chemical fluid transport” (CFT) and the end products deposited from the gas phase as “fluidites.” Treating iron meteorites as cosmic fluidites enables simple solutions to be found to the problem of how they formed and to numerous related and in some cases unresolved questions. This study is based on a thermodynamic trend analysis of solid–gas equilibrium reactions involving chlorine- and fluorine-containing compounds of 42 chemical elements that include a systematic examination of reaction dominance switching behavior. In order to assess the transport behavior of the individual elements, the reaction-conditioned pressures p MeX were calculated from the equilibrium constants. For a selected group of minerals, the relative propensity of these minerals to deposit from the gas phase was then derived from the equilibrium constants. The study shows that octahedrites, hexahedrites and ataxites formed as a result of the transport of metal chlorides and fluorides (CFT) during accretion within the solar nebula. Siderophile elements are characterized by the similarities in their chemical transport properties. These chemical properties of the elements, expressed in the form of the reaction-conditioned pressure, play a key role in determining the chemical composition of iron meteorites. The mobilization process that leads to the formation of the gaseous metal halides MeX includes the reduction of oxides. The deposition of nickel–iron bodies occurs via back reaction after the transport of the gaseous halides. The back reaction leads to the thermodynamically favored deposition of schreibersite before troilite and of troilite before kamacite/taenite. The deposition temperature of octahedrites and hexahedrites lies below the temperature at which Widmanstätten patterns would be destroyed, while that of ataxites lies slightly above. Similarly, the occurrence of thermally instable cohenite in meteorites provides further support for the fluidite character of irons. The variation in the trace element concentrations in iron meteorites is explained by enrichment and depletion mechanisms in the gas phase. The striking correlation between gallium and germanium abundances in iron meteorites is the result of similarities regarding the mobilization phase and the reaction dominance switching behavior of both elements, and crystal isomorphism. These findings are supported by numerous arguments that provide evidence for the CFT model. The occurrence of the mineral lawrencite FeCl 2 in meteorites is interpre","PeriodicalId":91169,"journal":{"name":"ScienceOpen research","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84589181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Digital Archaeology Collection on ScienceOpen: Meaning and Purpose ScienceOpen上的数字考古馆藏:意义与目的

ScienceOpen research Pub Date : 2017-10-03 DOI: 10.14293/S2199-1006.1.SOR-SOCSCI.E0TQOE.v1

D. Hagmann

引用次数: 1

Multivariate statistics and visualisation in earth science: It's not only about maps 地球科学中的多元统计和可视化:不仅仅是地图

ScienceOpen research Pub Date : 2017-09-26 DOI: 10.14293/S2199-1006.1.SOR-EARTH.ELCP1Y.v1

Dasapta Erwin Irawan

引用次数: 0

ScienceOpen research Pub Date : 2017-06-13 DOI: 10.14293/S2199-1006.1.SOR-MED.AXK5RB.V2

S. Shu

引用次数: 0

Better latte than never: Is coffee good for you health?: The science of coffee 拿铁总比没有好:咖啡对你的健康有好处吗?咖啡的科学

ScienceOpen research Pub Date : 2017-06-08 DOI: 10.14293/S2199-1006.1.SOR-MED.E2LMOE.v1

J. Tennant

引用次数: 0

Introduction: Open Source Cell Simulators: A curated guide to leading open source discrete cell models 介绍:开源单元模拟器:一个策划指南，领先的开源离散单元模型

ScienceOpen research Pub Date : 2017-05-12 DOI: 10.14293/S2199-1006.1.SOR-LIFE.EIOYQO.V1

P. Macklin

引用次数: 0

Glucocorticoid Signaling in Stress-Related Psychiatric Disorders Uncovered by Dexamethasone-Induced Gene Expression 地塞米松诱导的基因表达揭示应激相关精神疾病中的糖皮质激素信号

ScienceOpen research Pub Date : 2017-05-07 DOI: 10.14293/S2199-1006.1.SOR-UNCAT.EITGTN.v1

A. Menke

{"title":"Glucocorticoid Signaling in Stress-Related Psychiatric Disorders Uncovered by Dexamethasone-Induced Gene Expression","authors":"A. Menke","doi":"10.14293/S2199-1006.1.SOR-UNCAT.EITGTN.v1","DOIUrl":"https://doi.org/10.14293/S2199-1006.1.SOR-UNCAT.EITGTN.v1","url":null,"abstract":"Major depressive disorder (MDD) is a common, serious and in some cases life‐threatening condition and affects approximately 350 million people globally (Otte et al., 2016). The magnitude of the clinical burden reflects the limited effectiveness of current available therapies. The current prescribed antidepressants are based on modulating monoaminergic neurotransmission, i.e. they improve central availability of serotonin, norepinephrine and dopamine. However, they are associated with a high rate of partial or non-response, delayed response onset and limited duration. Actually more than 50% of the patients fail to respond to their first antidepressant they receive.\u0000Therefore there is a need of new treatment approaches targeting other systems than the monoaminergic pathway. One of the most robust findings in biological psychiatry is a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis in major depression (Holsboer, 2000). Many studies observed an increased production of the corticotropin-releasing hormone (CRH) in the hypothalamus, leading to an increased release of adrenocorticotropic hormone (ACTH) from the pituitary and subsequently to an enhanced production of cortisol in the adrenal cortex. Due to an impaired sensitivity of the glucocorticoid receptor (GR) the negative feedback mechanisms usually restoring homeostasis after a stress triggered cortisol release are not functioning properly (Holsboer, 2000, Pariante and Miller, 2001).\u0000However, treatment strategies targeting the GR or the CRH receptors have not been successful for a general patient population. Selecting the right patients for these treatment alternatives may improve therapy outcome, since a dysregulation of the HPA axis affects only 40-60 % of the depressed patients. Thus, patients with a dysregulated HPA axis have first to be identified and then allocated to a specific treatment regime. Tests like the dexamethasone-suppression-test (DST) or the dex-CRH test have been shown to uncover GR sensitivity deficits, but are not routinely applied in the clinical setting. Recently, the dexamethasone-induced gene expression could uncover GR alterations in participants suffering from major depression and job-related exhaustion (Menke et al., 2012, Menke et al., 2013, Menke et al., 2014, Menke et al., 2016). Actually, by applying the dexamethasone-stimulation test we found a GR hyposensitivity in depressed patients (Menke et al., 2012) and a GR hypersensitivity in subjects with job-related exhaustion (Menke et al., 2014). These alterations normalized after clinical recovery (Menke et al., 2014).\u0000Interestingly, the dexamethasone-stimulation test also uncovered FKBP5 genotype dependent alterations in FKBP5 mRNA expression in depressed patients and healthy controls (Menke et al., 2013). FKBP5 is a co-chaperone which modulates the sensitivity of the GR (Binder, 2009).\u0000In addition, the dexamethasone-stimulation test provided evidence of common genetic variants that modulate the immedia","PeriodicalId":91169,"journal":{"name":"ScienceOpen research","volume":"142 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82890670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Sodium polyphosphate and polyethylenimine enhance the antimicrobial activities of plant essential oils 聚磷酸钠和聚乙烯亚胺增强了植物精油的抑菌活性

ScienceOpen research Pub Date : 2016-12-29 DOI: 10.14293/S2199-1006.1.SOR-LIFE.Z72TP0.V1

Heidi A. Wright, B. Brehm-Stecher

{"title":"Sodium polyphosphate and polyethylenimine enhance the antimicrobial activities of plant essential oils","authors":"Heidi A. Wright, B. Brehm-Stecher","doi":"10.14293/S2199-1006.1.SOR-LIFE.Z72TP0.V1","DOIUrl":"https://doi.org/10.14293/S2199-1006.1.SOR-LIFE.Z72TP0.V1","url":null,"abstract":"Plant extracts have been used for millennia for treatment of disease, with much recent interest focusing on the antimicrobial activities of plant essential oils (EOs). Although EOs are active against common microbial pathogens, their effective use as topical, environmental, or food antimicrobials will require EO-based formulations with enhanced antimicrobial activities. In this study, two polyionic compounds, sodium polyphosphate (polyP, a polyanion) and polyethylenimine (PEI, a polycation), were evaluated for their abilities to enhance the antimicrobial activities of six EOs against the human pathogens Escherichia coli O157:H7, Salmonella enterica subsp. enterica ser. Minnesota, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, and Candida albicans. EOs tested were cinnamon, clove, regular and redistilled oregano, and two types of thyme oil. EOs were examined via disk diffusion and broth microdilution, either alone or in the presence of subinhibitory levels of polyP or PEI. Both polyP and PEI were found to be effective enhancers of EO activity against all strains examined, and calculation of fractional inhibitory indices for select EO/organism pairings demonstrated that true synergy was possible with this en‐ hancement approach. Experiments with a deep-rough strain of S. Minnesota probed the role of the outer membrane in both intrinsic resistance to EOs and enhancement by polyions. The use of polyP and PEI for boosting the antimicrobial activities of EOs may eventually facilitate the development of more effective EObased antimicrobial treatments for use in applications such as wound treatment, surface disinfection, or as generally recognized as safe antimicrobials for use in foods or on food contact surfaces.","PeriodicalId":91169,"journal":{"name":"ScienceOpen research","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79267561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Wide-spectrum biomimetic antimicrobial systems 广谱仿生抗菌系统

ScienceOpen research Pub Date : 2016-12-29 DOI: 10.14293/S2199-1006.1.SOR-LIFE.CMGPSN.V1

Heidi A. Wright, B. Brehm-Stecher

{"title":"Wide-spectrum biomimetic antimicrobial systems","authors":"Heidi A. Wright, B. Brehm-Stecher","doi":"10.14293/S2199-1006.1.SOR-LIFE.CMGPSN.V1","DOIUrl":"https://doi.org/10.14293/S2199-1006.1.SOR-LIFE.CMGPSN.V1","url":null,"abstract":"Antimicrobial peptides (AMPs) are effective components of the host immune response and are widely distributed throughout nature. Recently, nontoxic antimicrobial polymers that mimic the structures of naturally occurring AMPs have been designed and are under development commercially as novel therapeutics. These compounds have several potential advantages over natural AMPs, including greater stability and reduced immunogenicity compared to natural peptides, relatively simple and scalable syntheses and the ability to tailor or “fine tune” their activities through combinatorial approaches. In previous work, we demonstrated the utility of certain generally regarded as safe (GRAS) flavorant and aroma compounds as enhancers of uptake and activity of clinically important antibiotics (Brehm-Stecher & Johnson, 2003). Here, we have extended this approach to include enhancement of biomimetic antimicrobial polymers. Three low molecular weight (<1000 >D), broad-spectrum arylamide polymers (PolyMedix, Inc., Radnor, PA) were examined for their antimicrobial activities against gram-negative bacteria, gram-positive bacteria, yeast and filamentous fungi, both alone and when co-administered with sesquiterpenoid enhancers. Assay formats included disk diffusion, automated turbidimetry, time course (kinetic) plating of antimicrobial-treated cell suspensions, outer membrane assays with 1-N-phenylnaphthylamine (NPN) and transmission electron microscopy (TEM). Although results differed according to the polymer and test organism used, treatments containing sesquiterpenoids were marked by either increased ZOIs, decreased MICs or more rapid inactivation when compared with polymer-only treatments. Antimicrobial activity, expressed as decimal reduction times (D-value), showed that after 5 min, the combination of sesquiterpenoid and polymer was significantly different from the controls (p < 0.05) with a D-value of 3.92 min when incubated with Escherichia coli ATCC 25922. Collectively, our results indicate that the combination of sesquiterpenoidenhancing agents with biomimetic antimicrobial polymers shows promise for the development of new, fasteracting and more broadly effective antimicrobial therapies.","PeriodicalId":91169,"journal":{"name":"ScienceOpen research","volume":"319 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77136518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A quantum theory of spacetime in spinor formalism and the physical reality of cross-ratio representation: the equation of density parameters of dark energy, matter, and ordinary matter is derived: ΩM2 = 4 Ωb ΩΛ 旋量形式的时空量子理论和交叉比表示的物理现实:推导了暗能量、物质和普通物质的密度参数方程:ΩM2 = 4 Ωb ΩΛ

ScienceOpen research Pub Date : 2016-10-04 DOI: 10.14293/S2199-1006.1.SOR-PHYS.A4HPPH.V1

Jackie Liu

{"title":"A quantum theory of spacetime in spinor formalism and the physical reality of cross-ratio representation: the equation of density parameters of dark energy, matter, and ordinary matter is derived: ΩM2 = 4 Ωb ΩΛ","authors":"Jackie Liu","doi":"10.14293/S2199-1006.1.SOR-PHYS.A4HPPH.V1","DOIUrl":"https://doi.org/10.14293/S2199-1006.1.SOR-PHYS.A4HPPH.V1","url":null,"abstract":"By theorizing the physical reality through the deformation of an arbitrary cross-ratio, we leverage Galois differential theory to describe the dynamics of isomonodromic integratable system. We found a new description of curvature of spacetime by the equivalency of isomonodromic integratable system and Penrose’s spinor formalism of general relativity. Using such description, we hypothetically quantize the curvature of spacetime (gravity) and apply to the problem of the evolution of the universe. The Friedmann equation is recovered and compared so that the mathematical relationship among dark energy, matter (dark matter + ordinary matter), and ordinary matter, XM ’ 4Xb XK, is derived; the actual observed results are compared to this equation (calculated ΩM = 0.33 vs. observed ΩM = 0.31); the model might explain the origin of dark energy and dark matter of the evolution of the universe. INTRODUCTION We looked for the simplest mathematical object to identify the underlying reality of nature, and we found it to be cross-ratio. By defining cross-ratio over Riemann sphere, infinity is just another usual point; similarly, there shouldn’t be any point in the universe more special than others. However, the variety of nature must be realized as a condition for such an underlying object. In “Cross-ratio arbitrariness and the constraint to the parameter space of projective space basis” section, the article explains how potential physical varieties come from different representations of the same thing – cross-ratio deformation. So, the cross-ratio consists of both simplicity and variety. A successful example is like Einstein’s masterpiece – general theory of relativity. Although Einstein’s field equation is simple, many interesting solutions emerged. In “Cassidy’s work on isomonodromic system” section, we introduce Galois differential theory and related Cassidy’s work. It is a mathematical machinery to manifest the deformation of cross-ratio. Cassidy’s work consists of introducing a 2 by 2 matrix differential equation and related isomonodromic integratable system, so it can describe the deformation. By such machinery, we formulate an alternative theory of the dynamics of curvature of spacetime to recover the spinor general relativity equivalent counterpart (for which a brief introduction is given in “Brief overview of spinor formulation of general relativity” section). By such connection, we hypothetically claim the origin of spacetime is from the iso‐ monodromic integratable system, and spacetime is more fundamentally described by the curvature rather than metric or coordinated mathematical framework, that is, spinor formulation of general relativity might be more fundamental than classical general relativity; a similar argument was postulated by Penrose (1960). In “As an application to the problem of modeling the universe evolution” section, we apply the calculation of the deformation of the isomonodromic integratable system with certain simplified condition","PeriodicalId":91169,"journal":{"name":"ScienceOpen research","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89723625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2