670 research outputs found
Some Structural Changes Observed in the Transformation of Wood into Charcoal1
On the basis of measurements of microtomed cubes of white oak and on resultant charcoal, dimensional changes occurring on the conversion of wood into charcoal are: tangential, -25.68%, radial, -15.45%, and longitudinal, -11.43%. Light microscopic examination of charcoal reveals residues of combustion present in cell cavities. Electron microscopic examination indicates that the original fibrillar arrangement of the cell wall has been replaced with a smooth, "amorphous-appearing" wall structure
A Note on Effects of Sewage Effluent Irrigation on Specific Gravity and Growth Rate of White and Red Oaks
A 2.5-acre forested terrace of mixed hardwoods (predominately oak) in southern Missouri was sprinkler-irrigated with treated sewage effluent. Ninety-two oak trees were sampled (increment cores) at breast height. There were 41 white oaks and 52 red oaks. Growth rate increased significantly for white oaks and specific gravity increased significantly for red oaks
Antiproliferative, antimicrobial, and antifungal activities of polyphenol extracts from Ferocactus species
Polyphenols, obtained from natural resources, may possess important pharmacological
effects. The polyphenolic profiles of the stem extracts of six Ferocactus species (sp.): F. gracilis, F. pottsii,
F. herrerae, F. horridus, F. glaucescens, and F. emoryi, were measured using high-performance liquid
chromatography (HPLC) with diode-array detection (DAD). Additionally, anticancer, antibacterial,
and antifungal activities were examined. Results showed the presence of high to moderate amounts
of polyphenols in the extracts (phenolic acids: Protocatechuic acid, 3,4-dihydroxyphenylacetic
acid, cffeic acid, and vanillic acid; flavonoids: Rutoside and quercitrin). The highest amounts of
3,4-dihydroxyphenylacetic acid were found in F. glaucescens ((132.09 mg 100 dry weight (DW)),
F. pottsii (75.71 mg 100 DW), and F. emoryi (69.14 mg 100 DW) while rutoside content was
highest in F. glaucescens (107.66 mg 100 DW). Maximum antiproliferative activities were observed
against HeLa and Jurkat cancer cells, with F. glaucescens, F. emoryi, and F. pottsii showing the highest
anticancer activity. Most bacteria were sensitive to Ferocactus sp. stem extracts. Escherichia coli and
Staphylococcus aureus were the most sensitive. Excellent antifungal effects were observed against
Aspergillus ochraceus and A. niger. However, Penicillium funiculosum, P. ochrochloron, and Candida
albicans were relatively resistant. This is the first study reporting novel sources of polyphenols in
Ferocactus sp. with anticancer and antimicrobial activities
Gaseous chemistry for a Titan's atmospheric plasma experimental simulation
We present the first study of gaseous composition monitoring for the PAMPRE experiment, which simulates Titan's atmospheric chemistry by radio-frequency N 2-CH 4 plasma. Methane consumption is quantified for various N 2-CH 4 gas mixtures. Moreover in situ mass spectrometry (MS) and ex-situ gas chromatography coupled with mass spectrometry (GC-MS) analyses reveal a large dominance of nitrile species in the gas phase chemistry
Multi-model simulations of the impact of international shipping on Atmospheric Chemistry and Climate in 2000 and 2030
The global impact of shipping on atmospheric chemistry and radiative forcing, as well as the associated uncertainties, have been quantified using an ensemble of ten state-of-the-art atmospheric chemistry models and a predefined set of emission data. The analysis is performed for present-day conditions ( year 2000) and for two future ship emission scenarios. In one scenario ship emissions stabilize at 2000 levels; in the other ship emissions increase with a constant annual growth rate of 2.2% up to 2030 ( termed the "Constant Growth Scenario" (CGS)). Most other anthropogenic emissions follow the IPCC ( Intergovernmental Panel on Climate Change) SRES ( Special Report on Emission Scenarios) A2 scenario, while biomass burning and natural emissions remain at year 2000 levels. An intercomparison of the model results with observations over the Northern Hemisphere (25 degrees - 60 degrees N) oceanic regions in the lower troposphere showed that the models are capable to reproduce ozone (O-3) and nitrogen oxides (NOx= NO+ NO2) reasonably well, whereas sulphur dioxide (SO2) in the marine boundary layer is significantly underestimated. The most pronounced changes in annual mean tropospheric NO2 and sulphate columns are simulated over the Baltic and North Seas. Other significant changes occur over the North Atlantic, the Gulf of Mexico and along the main shipping lane from Europe to Asia, across the Red and Arabian Seas. Maximum contributions from shipping to annual mean near-surface O-3 are found over the North Atlantic ( 5 - 6 ppbv in 2000; up to 8 ppbv in 2030). Ship contributions to tropospheric O3 columns over the North Atlantic and Indian Oceans reach 1 DU in 2000 and up to 1.8 DU in 2030. Tropospheric O-3 forcings due to shipping are 9.8 +/- 2.0 mW/m(2) in 2000 and 13.6 +/- 2.3 mW/m(2) in 2030. Whilst increasing O-3, ship NOx simultaneously enhances hydroxyl radicals over the remote ocean, reducing the global methane lifetime by 0.13 yr in 2000, and by up to 0.17 yr in 2030, introducing a negative radiative forcing. The models show future increases in NOx and O-3 burden which scale almost linearly with increases in NOx emission totals. Increasing emissions from shipping would significantly counteract the benefits derived from reducing SO2 emissions from all other anthropogenic sources under the A2 scenario over the continents, for example in Europe. Globally, shipping contributes 3% to increases in O-3 burden between 2000 and 2030, and 4.5% to increases in sulphate under A2/CGS. However, if future ground based emissions follow a more stringent scenario, the relative importance of ship emissions will increase. Inter-model differences in the simulated O-3 contributions from ships are significantly smaller than estimated uncertainties stemming from the ship emission inventory, mainly the ship emission totals, the distribution of the emissions over the globe, and the neglect of ship plume dispersion
Malus baccata var. gracilis and Malus toringoides bark polyphenol studies and antioxidant, antimicrobial and anticancer activities
Exploring new sources of polyphenols with biological activities that work against human
diseases is the target of natural product studies. This study determined the polyphenol composition of
the bark of Malus species M. baccata var. gracilis (Rehder) T.C.Ku and M. toringoides (Rehder) Hughes,
using high-performance liquid chromatography with a diode-array detector (HPLC-DAD) analysis.
The antiproliferative, cytotoxic, antioxidant and antimicrobial applications of these extracts, as well
as the identified phenol, were studied. The HPLC-DAD analysis confirmed three polyphenols in the
extracts out of the 21 screened compounds: protocatechuic acid, gallic acid, and catechin. The major
constituents in M. baccata and M. toringoides were protocatechuic acid, at 3.16 and 7.15 mg 100 dry
weight (DW), respectively, and catechin, at 5.55 and 6.80 mg 100 DW, respectively. M. baccata
and M. toringoides bark extracts showed antioxidant activities using 2,2-diphenyl-1-picrylhydrazyl
(DPPH), -carotene bleaching, and ferric-reducing antioxidant power (FRAP) assays, which were
attributed to the dominance of protocatechuic acid. The highest antiproliferative and cytotoxic e ects
were against Jurkat cells. Against MCF-7 and Hela cells, there was necrotic cell accumulation in the
early apoptotic as well as the late apoptotic phase. The bark extracts showed noticeable antibacterial
e ects against Listeria monocytogenes, Bacillus cereus, and Escherichia coli. Protocatechuic acid showed
comparable results to bark extracts. There were antifungal effects against Aspergillus ochraceus, A. niger,
and Candida albicans, and the activities were higher than the commercial reagent. M. baccata and
M. toringoides could be considered as a new source of phenolic acids, including protocatechuic acid
with anticancer, antibacterial antifungal, and antioxidant-promising effects
Polyphenol content and biological activities of Ruta graveolens L. and Artemisia abrotanum L. in northern Saudi Arabia
Natural populations of Ruta graveolens L. and Artemisia abrotanum L. in northern Saudi
Arabia may be a rich source of natural polyphenols with potential biological activities. Therefore,
tentative high-performance liquid chromatography–diode array detection was used to analyze the
polyphenol contents of leaf extracts. R. graveolens mainly contained the phenolic acids chlorogenic
acid and p-coumaric acid and the flavonoids rutoside and quercetin, whereas those of A. abrotanum
mainly contained the phenolic acids isochlorogenic acid and rosmarinic acid and the flavonoid
quercetin. Leaf extracts of both species showed antioxidant activities due to the presence of quercetin,
chlorogenic acid, and p-coumaric acid as well as antiproliferative and cytotoxic activities against
cancer cells, which may be attributed to necrotic cell accumulation during the early and late apoptotic
periods. Both species also exhibited antibacterial activity, although the activity was higher in
R. graveolens due to the high contents of quercetin and other polyphenols. Finally, both species
exhibited antifungal activities, which were associated with specific polyphenols. This is the first
study to confirm the richness of polyphenols and wide spectrum of biological activities in natural
populations of R. graveolens and A. abrotanum in northern Saudi Arabia
Saudi Rosmarinus offcinalis and Ocimum basilicum L. polyphenols and biological activities
Investigating the polyphenolic profile of natural Rosmarinus offcinalis and Ocimum basilicum
populations may reveal essential compounds that have biological activities. Natural populations
of R. offcinalis and O. basilicum in Northern Riyadh were investigated by HPLC-DAD analyses.
Several polyphenols, including rosmarinic acid, gentisic acid, 3,4-dihydroxyphenylacetic acid,
rutoside, and others, out of 38 screened were confirmed. Rosmarinic acid was the major polyphenol
in both of R. offcinalis and O. basilicum. R. offcinalis methanolic leaf extracts contained other
phenols such as gentisic acid while O. basilicum contained also 3,4-dihydroxyphenylacetic acid and
rutoside as well as others. R. o cinalis showed higher antioxidant activities than O. basilicum using
2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and -carotene
bleaching assays. These higher activities are associated with a higher composition of rosmarinic
acid in leaf extracts. The antioxidant activities of O. basilicum were attributed to identified phenols
of rosmarinic acid, 3,4-dihydroxyphenylacetic acid, and rutoside. There were antiproliferative
and cytotoxic activities of leaf extracts, as well as identified polyphenols, against several cancer
cells. These activities were attributed to the accumulation of necrotic and apoptotic cells in treated
cancer cells with leaf extracts as well as identified polyphenols. The antibacterial and antifungal
activities of leaf extracts were mainly attributed to 3,4-dihydroxyphenylacetic acid and rutoside in
O. basilicum and rosmarinic acid and caffeic acid in R. offcinalis. This study proved that R. offcinalis and
O. basilicum natural populations might be considered as promising sources of natural polyphenols
with biological activities
The Kalahari and Grunehogna Cratons, and their placement within neoproterozoic Rodinia, defined by new U-Pb geochronology on large igneous provinces
Development of an approximate method for quantum optical models and their pseudo-Hermicity
An approximate method is suggested to obtain analytical expressions for the
eigenvalues and eigenfunctions of the some quantum optical models. The method
is based on the Lie-type transformation of the Hamiltonians. In a particular
case it is demonstrated that Jahn-Teller Hamiltonian can
easily be solved within the framework of the suggested approximation. The
method presented here is conceptually simple and can easily be extended to the
other quantum optical models. We also show that for a purely imaginary coupling
the Hamiltonian becomes non-Hermitian but -symmetric. Possible generalization of this approach is outlined.Comment: Paper prepared fo the "3rd International Workshop on Pseudo-Hermitian
Hamiltonians in Quantum Physics" June 2005 Istanbul. To be published in
Czechoslovak Journal of Physic
- …