1,071 research outputs found
Two methods of obtaining sol gel Nb2O5 thin films for electrochromic devices
Nb2O5 coatings prepared by the sol-gel route using the dip coating technique with sols prepared from alkoxide or chloroalkoxide (two different methods: sonocatalytic and conventional) precursors are a promising alternative for WO3 electrochromic coatings. The crystalline films (TT phase) sintered at 560 and 600 degrees C are transparent and present a deep blue colour under Li+ ion insertion. Electrochemical stability is excellent as these systems are fully reversible and stable and no change in colour, amount of charge exchanged and corrosion effect could be observed after 2000 voltammetry cycles between 2 and - 1.8 V versus Ag. The electrochemical and optical properties of these coatings have been determined as a function of sintering temperature. The superficial structure was visualized by atomic force microscopy (AFM) and scanning electron microscopy (SEM) and the Li+ diffusion coefficient was determined for both kinds of coatings
Campanian-Maastrichtian foraminiferal stratigraphy and palaeoenvironment of the Lower Tar Member in the Wadi Tar section, Western Sirte Basin (Libya)
Upper Campanian-Maastrichtian sections on the western flank of the Hun Graben in the Western Sirte Basin (WSB) are displaying two major type facies based on the foraminiferal assemblages. The first one indicates open-marine to outer-shelf conditions, and is represented by numerous bathy-pelagic planktonic foraminiferal species referable to the Radotruncana calcarata, Globotruncana aegyptiaca and the lower part of the Gansserina gansseri Zone (all late Campanian).The second type facies indicates an inner-shelf environment and is represented in the middle-upper part of the Gansserina gansseri Zone (early Maastrichtian) and Racemiguembelina fructicosa (late Maastrichtian) dominated by epi-pelagic planktonic and large benthic foraminifers. Large benthic foraminiferal index species Siderolites calcitrapoides Lamarck and Omphalocyclus macroporus (Lamarck) occur in abundance by the middle-late Maastrichtian. Correlation between planktonic foraminiferal zonation and large benthic foraminiferal zonation is given. An open-marine to outer-shelf environment passed into shallower marine conditions during the late Campanian-early Maastrichtian to late Maastrichtian, then a slight deepening and again shallowing is noticed
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 profile and antimicrobial and cytotoxic activities of natural Mentha × piperita and Mentha longifolia opulations in northern Saudi Arabia
New sources of polyphenols with anticancer, antioxidant, and antimicrobial properties in
arid environments are critical for the development of alternative medicines and natural remedies. This
study explored the polyphenol profiles and biological activities of methanolic leaf extracts from natural
Mentha × piperita and Mentha longifolia populations in northern Saudi Arabia. Chromatographic
analyses identified several polyphenols in M. × piperita including phenolic acids: rosmarinic acid
(1547.6 mg/100 g DW (dry weight)), cryptochlorogenic acid (91.7 mg/100 g DW), and chlorogenic
acid (69.4 mg/100 g DW), as well as flavonoids: naringin (328.8 mg/100 g DW) and cynaroside
(162.8 mg/100 g DW). The major polyphenols in M. longifolia were: rosmarinic acid (781.6 mg/100 g
DW), cryptochlorogenic acid (191.1 mg/100 g DW), p-coumaric acid (113.0 mg/100 g DW), m-coumaric
acid (112.2 mg/100 g DW), and chlorogenic acid (63.8 mg/100 g DW). M. × piperita and M. longifolia
leaf extracts had high antioxidant activities due to the major polyphenols (cynaroside, rosmarinic
and cryptochlorogenic acids). M. × piperita had higher activities against di erent cancer cells than
M. longifolia. Naringin, cryptochlorogenic acid, and rosmarinic acid had the highest activities against
cancer cells. The leaf extracts had antibacterial e ects against most bacteria species (Pseudomonas
aeruginosa was most sensitive), which was attributed to the polyphenols. Antifungal activities were
similarly broad (Aspergillus flavus was most sensitive) and attributed to naringin, cryptochlorogenic
acid, and ca eic acid. Populations of M. × piperita and M. longifolia in Northern Riyadh may be a
valuable source of natural biologically active compounds
Genetic and environmental influences on plasma homocysteine: results from a Danish twin study
Interactions of polar lipids with cholesteryl ester multilayers elucidate tear film lipid layer structure
Purpose: The tear film lipid layer (TFLL) covers the tear film, stabilizing it and providing a protective barrier against the environment. The TFLL is divided into polar and non-polar sublayers, but the interplay between lipid classes in these sublayers and the structure-function relationship of the TFLL remains poorly characterized. This study aims to provide insight into TFLL function by elucidating the interactions between polar and non-polar TFLL lipids at the molecular level. Methods: Mixed films of polar O-acyl-omega-hydroxy fatty acids (OAHFA) or phospholipids and non-polar cholesteryl esters (CE) were used as a model of the TFLL. The organization of the films was studied by using a combination of Brewster angle and fluorescence microscopy in a Langmuir trough system. In addition, the evaporation resistance of the lipid films was evaluated. Results: Phospholipids and OAHFAs induced the formation of a stable multilamellar CE film. The formation of this film was driven by the interdigitation of acyl chains between the monolayer of polar lipids and the CE multilayer lamellae. Surprisingly, the multilayer structure was destabilized by both low and high concentrations of polar lipids. In addition, the CE multilayer was no more effective in resisting the evaporation of water than a polar lipid monolayer. Conclusions: Formation of multilamellar films by major tear film lipids suggest that the TFLL may have a similar structure. Moreover, in contrast to the current understanding, polar TFLL lipids may not mainly act by stabilizing the non-polar TFLL sublayer, but through a direct evaporation resistant effect.Peer reviewe
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 influence of warm ischemia elimination on kidney injury during transplantation - Clinical and molecular study
Kidney surface cooling was used during implantation to assess the effect of warm ischemia elimination on allograft function, histological changes and immune-related gene expression. 23 recipients were randomly assigned to a group operated on with kidney surface cooling during implantation (ice bag technique, IBT group), and the other 23 recipients receiving the contralateral kidney from the same donor were operated on with a standard technique. Three consecutive kidney core biopsies were obtained during the transplantation procedure: after organ recovery, after cold ischemia and after reperfusion. Gene expression levels were determined using low-density arrays (Format 32, TaqMan). The IBT group showed a significantly lower rate of detrimental events (delayed graft function and/or acute rejection, p = 0.015) as well as higher glomerular filtration rate on day 14 (p = 0.026). A greater decrease of MMP9 and LCN2 gene expression was seen in the IBT group during total ischemia (p = 0.003 and p = 0.018). Elimination of second warm ischemia reduced the number of detrimental events after kidney transplantation, and thus had influence on the short-term but not long-term allograft function. Surface cooling of the kidney during vascular anastomosis may reduce some detrimental effects of immune activation resulting from both brain death and ischemia-reperfusion injury
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