241 research outputs found
Hypotensive Activity of Moringa oleifera Lam (Moringaceae) Root Extracts and its Volatile Constituents
Purpose: To explore the hypotensive activity and chemical composition of Moringa oleifera Lam (Moringaceae) roots.Methods: The fresh roots of M. oleifera was cut into small pieces and successively extracted with petroleum ether (PE) and dichloromethane (DC). PE extract was further divided into MRP and MRP -1. DC extract showed a thick mass during evaporation which was separated as MRDC - IN. The mother liquor left was divided into MRDC and MRDC -1. All residues were analyzed by gas chromatographymass spectroscopy (GC-MS) using ZB-5 column. Identification of each extract and fraction was based on comparison of their retention indices (RI), by co-injecting authentic compounds, as well as by comparing literature data available in NIST Standard Reference Database. Hypotensive activity was determined on urethane-anesthetized normotensive Sprague Dawly rats.Results: Petroleum ether (MRP) and dichloromethane (MRDC) extracts of M. oleifera roots showed 50.06 ± 3.48 and 48.16 ± 1.79 % fall in mean arterial blood pressure (MABP), respectively, at a dose of 30 mg/kg (p < 0.01 and p < 0.05, respectively) compared with control. GC-MS analysis of MRP and MRDC extracts and fractions resulted in the identification of seventy four (74) compounds. Methyl hexadecanoate (7, 20.3 %) , stigmastan - 3, 5, diene (24, 19.32 %), methyl 14-hydroxy-5-tetradecenoate (9, 19.22 %), 1 , 11 diphenyl undecane (47, 18.78 %) and cyclopentanyl hexadecane (39, 14.44 %) were the major constituents among the various hydrocarbons, fatty acids, esters, alcohols, aldehydes, isothiocyanate, aromatics, steroids, terphenyl and sulphur-containing compounds. Conclusion: The findings reveal the hypotensive potential of M. oleifera roots and the presence of specific hydrocarbons, fatty acid esters, thioureides, steroids and isothiocyanates in active fractions. Further study is required to determine the suitability of the plant as an antihypertensive remedy.Keywords: Moringa oleifera, Methyl hexadecanoate, Methyl 14-hydroxy-5-tetradecenoate, Petroleum ether, Stigmastan - 3, 5, diene, Cyclopentanyl hexadecan
Viscosity of fluid membranes measured from vesicle deformation
Viscosity is a key mechanical property of cell membranes that controls
time-dependent processes such as membrane deformation and diffusion of embedded
inclusions. Despite its importance, membrane viscosity remains poorly
characterized because existing methods rely on complex experimental designs
and/or analyses. Here, we describe a facile method to determine the viscosity
of bilayer membranes from the transient deformation of giant unilamellar
vesicles induced by a uniform electric field. The method is non-invasive, easy
to implement, probe-independent, high-throughput, and sensitive enough to
discern membrane viscosity of different lipid types, lipid phases, and polymers
in a wide range, from 10 to 10 Pa.s.m. It enables fast and
consistent collection of data that will advance understanding of biomembrane
dynamics
2 and 3-dimensional Hamiltonians with Shape Invariance Symmetry
Via a special dimensional reduction, that is, Fourier transforming over one
of the coordinates of Casimir operator of su(2) Lie algebra and 4-oscillator
Hamiltonian, we have obtained 2 and 3 dimensional Hamiltonian with shape
invariance symmetry. Using this symmetry we have obtained their eigenspectrum.
In the mean time we show equivalence of shape invariance symmetry and Lie
algebraic symmetry of these Hamiltonians.Comment: 24 Page
The typology of connectivity in landscape architecture: a review of studies on landscape connectivity (LC)
Connectivity is an important landscape characteristic that is essential for health, welfare and aesthetic
values in human societies as well as for the protection of native ecosystems. Diversity in objectives,
approaches, definitions and methods in studies on connectivity and its widespread use in the field of
landscape ecology are reasons why Landscape Connectivity (LC) in landscape architecture has been
deemed as the counterpart of Ecological Connectivity leading to neglect of other aspects of this
comprehensive concept. This study, reviews and classifies studies carried out in the field of
landscape with a focus on connectivity in order to achieve a comprehensive definition of LC and its
various components in landscape architecture literature. The research method used in this study was
quantitative-qualitative. In the first phase, the literature was collected using library research and
internet search via a descriptive-analytical approach. Then, an inductive constructionist strategy using
Delphi technique was used to classify and categorize relevant studies, and logical argumentation was
used to develop the concept of LC in landscape architecture literature. Finally, the objectivist
Descriptive/Synthetic Modelling strategy was used to provide a conceptual model of urban landscape
connectivity (ULC). The key finding of this study is the researcher-made conceptual model of ULC, its
corresponding components and parameters with the viewpoint of landscape architecture
From green remediation to polymer hybrid fabrication with improved optical band gaps
The present work proposed a novel approach for transferring high-risk heavy metals tometal complexes via green chemistry remediation. The method of remediation of heavy metals developed in the present work is a great challenge for global environmental sciences and engineering because it is a totally environmentally friendly procedure in which black tea extract solution is used. The FTIR study indicates that black tea contains enough functional groups (OH and NH), polyphenols and conjugated double bonds. The synthesis of copper complex was confirmed by the UV-vis, XRD and FTIR spectroscopic studies. The XRD and FTIR analysis reveals the formation of complexation between Cu metal complexes and Poly (Vinyl Alcohol) (PVA) host matrix. The study of optical parameters indicates that PVA-based hybrids exhibit a small optical band gap, which is close to inorganic-based materials. It was noted that the absorption edge shifted to lower photon energy. When Cu metal complexes were added to PVA polymer, the refractive index was significantly tuned. The band gap shifts from 6.2 eV to 1.4 eV for PVA incorporated with 45 mL of Cu metal complexes. The nature of the electronic transition in hybrid materials was examined based on the Taucs model, while a close inspection of the optical dielectric loss was also performed in order to estimate the optical band gap. The obtained band gaps of the present work reveal that polymer hybrids with sufficient film-forming capability could be useful to overcome the drawbacks associated with conjugated polymers. Based on the XRD results and band gap values, the structure-property relationships were discussed in detail. © 2019 by the authors. Licensee MDPI, Basel, Switzerland
Assessing membrane material properties from the response of giant unilamellar vesicles to electric fields
Knowledge of the material properties of membranes is crucial to understanding cell viability and physiology. A number of methods have been developed to probe membranes in vitro, utilizing the response of minimal biomimetic membrane models to an external perturbation. In this review, we focus on techniques employing giant unilamellar vesicles (GUVs), model membrane systems, often referred to as minimal artificial cells because of the potential they offer to mimick certain cellular features. When exposed to electric fields, GUV deformation, dynamic response and poration can be used to deduce properties such as bending rigidity, pore edge tension, membrane capacitance, surface shear viscosity, excess area and membrane stability. We present a succinct overview of these techniques, which require only simple instrumentation, available in many labs, as well as reasonably facile experimental implementation and analysis.
Graphical abstrac
Fluctuation spectroscopy of giant unilamellar vesicles using confocal and phase contrast microscopy
A widely used method to measure the bending rigidity of bilayer membranes is
fluctuation spectroscopy, which analyses the thermally-driven membrane
undulations of giant unilamellar vesicles recorded with either phase-contrast
or confocal microscopy. Here, we analyze the fluctuations of the same vesicle
using both techniques and obtain consistent values for the bending modulus. We
discuss the factors that may lead to discrepancies
A study of tensile test on open-cell aluminum foam sandwich
Aluminum foam sandwich (AFS) panels are one of the growing materials in the various industries because of its lightweight behavior. AFS also known for having excellent
stiffness to weight ratio and high-energy absorption. Due to their advantages, many researchers’ shows an interest in aluminum foam material for expanding the use of foam
structure. However, there is still a gap need to be fill in order to develop reliable data on mechanical behavior of AFS with different parameters and analysis method approach. Least of researcher focusing on open-cell aluminum foam and statistical analysis. Thus, this research conducted by using open-cell aluminum foam core grade 6101 with aluminum sheets skin tested under tension. The data is analyzed using full factorial in JMP statistical analysis software (version 11). ANOVA result show a significant value of the model which less than 0.500. While scatter diagram and 3D plot surface profiler found that skins thickness gives a significant impact to stress/strain value compared to core thickness
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