685 research outputs found
Adsorption of phenol/tyrosol from aqueous solutions on macro-reticular aromatic and macro-porous polystyrene cross-linked with divinylbenzene polymeric resins
The current work aims at separating by adsorption of low-molecular-weight organic compounds in a
nanofiltration concentrate of the olive mill wastewaters. The experimental investigations on adsorption of
phenol/tyrosol in single and binary systems were conducted in batch mode by using the commercially
available macroporous resins FPX66 and MN202. The structures of such resins were examined by FTIR
before and after adsorption. The operating parameters affecting the adsorption process such as resin dosage,
contact time, pH, and initial concentration of phenol/tyrosol were investigated. Fast phenol and tyrosol uptakes
were observed for both resins. It can be attributed to their physical properties, for instance high specific area
and microporous area. The adsorption selectivity of phenol is larger than tyrosol when using FPX66 resin, but
smaller if MN202 resin is used. Acidic pH appeared to be always favourable for the adsorption. A synergetic
effect between solutes was observed since adsorption of phenol and tyrosol in the binary systems was faster
than the individual sorption of each solute. Five isotherms namely Langmuir, Freundlich, DubininRadushkevich,
Temkin and Redlich-Peterson were selected to fit the obtained equilibrium experimental data.
Finally, desorption of the examined compounds with ethanol (EtOH) allowed a maximum around 85 % of
phenol, and equal to 94 % of tyrosol on FPX66 and MN202 resins
Adsorption of phenol/tyrosol from aqueous solutions on macro-reticular aromatic and macro-porous polystyrene cross-linked with divinylbenzene polymeric resins
The current work aims at separating by adsorption of low-molecular-weight organic compounds in a
nanofiltration concentrate of the olive mill wastewaters. The experimental investigations on adsorption of
phenol/tyrosol in single and binary systems were conducted in batch mode by using the commercially
available macroporous resins FPX66 and MN202. The structures of such resins were examined by FTIR
before and after adsorption. The operating parameters affecting the adsorption process such as resin dosage,
contact time, pH, and initial concentration of phenol/tyrosol were investigated. Fast phenol and tyrosol uptakes
were observed for both resins. It can be attributed to their physical properties, for instance high specific area
and microporous area. The adsorption selectivity of phenol is larger than tyrosol when using FPX66 resin, but
smaller if MN202 resin is used. Acidic pH appeared to be always favourable for the adsorption. A synergetic
effect between solutes was observed since adsorption of phenol and tyrosol in the binary systems was faster
than the individual sorption of each solute. Five isotherms namely Langmuir, Freundlich, DubininRadushkevich,
Temkin and Redlich-Peterson were selected to fit the obtained equilibrium experimental data.
Finally, desorption of the examined compounds with ethanol (EtOH) allowed a maximum around 85 % of
phenol, and equal to 94 % of tyrosol on FPX66 and MN202 resins
Standard monomial theory for wonderful varieties
A general setting for a standard monomial theory on a multiset is introduced
and applied to the Cox ring of a wonderful variety. This gives a degeneration
result of the Cox ring to a multicone over a partial flag variety. Further, we
deduce that the Cox ring has rational singularities.Comment: v3: 20 pages, final version to appear on Algebras and Representation
Theory. The final publication is available at Springer via
http://dx.doi.org/10.1007/s10468-015-9586-z. v2: 20 pages, examples added in
Section 3 and in Section
In vitro ion chelating, antioxidative mechanism of extracts from fruits and barks of tetrapleura tetraptera and their protective effects against fenton mediated toxicity of metal ions on liver homogenates
The aim of the present study was to investigate the antioxidant activity and protective potential of T. tetraptera extracts against ion toxicity. The antioxidant activity of the extracts was investigated spectrophotometrically against several radicals (1,1-diphenyl-2-picrylhydrazyl (DPPH•), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS•), hydroxyl radical (HO•), and nitric oxide (NO•)), followed by the ferric reducing power, total phenols, flavonoid, and flavonol contents. The effects of the extracts on catalase (CAT), superoxide dismutase (SOD), and peroxidase activities were also determined using the standard methods as well as the polyphenol profile using HPLC. The results showed that the hydroethanolic extract of T. tetraptera (CFH) has the lowest ICvalue with the DPPH, ABTS, OH, and NO radicals. The same extract also exhibited the significantly higher level of total phenols (37.24 ± 2.00 CAE/g dried extract); flavonoids (11.36 ± 1.88 QE/g dried extract); and flavonols contents (3.95 ± 0.39 QE/g dried extract). The HPLC profile of T. tetraptera revealed that eugenol (958.81 ± 00 mg/g DW), quercetin (353.78 ± 00 mg/g DW), and rutin (210.54 ± 00 mg/g DW) were higher in the fruit than the bark extracts. In conclusion, extracts from T. tetraptera may act as a protector against oxidative mediated ion toxicity. © 2015 Bruno Moukette Moukette et al
A combinatorial smoothness criterion for spherical varieties
We suggest a combinatorial criterion for the smoothness of an arbitrary
spherical variety using the classification of multiplicity-free spaces,
generalizing an earlier result of Camus for spherical varieties of type .Comment: 14 pages, 2 table
Impaired heart rate variability predicts clinical deterioration and progressive organ failure in emergency department sepsis patients
Normality and smoothness of simple linear group compactifications
If G is a complex semisimple algebraic group, we characterize the normality
and the smoothness of its simple linear compactifications, namely those
equivariant GxG-compactifications which possess a unique closed orbit and which
arise in a projective space of the shape P(End(V)), where V is finite
dimensional rational G-module. Both the characterizations are purely
combinatorial and are expressed in terms of the highest weights of V. In
particular, we show that Sp(2r) (with r > 0) is the unique non-adjoint simple
group which admits a simple smooth compactification.Comment: v2: minor changes, final version. To appear in Math.
Daylight saving time and acute myocardial infarction: a meta-analysis
Background
The current evidence on the effects of daylight saving time (DST) transitions on major cardiovascular diseases is limited, and available results are conflicting. We carried out the first meta-analysis aimed at evaluating the risk of acute myocardial infarction (AMI) following DST transitions.
Methods
We searched MedLine and Scopus up to December 31, 2018, with no language restriction, to retrieve cohort or case-control studies evaluating AMI incidence among adults (≥18y) in the week following spring and/or autumn DST shifts versus control periods. A summary relative risk of AMI was computed after: (1) spring, (2) autumn, (3) both transitions considered together versus control weeks. Stratified analyses were performed by gender and age. Data were combined using a generic inverse-variance approach.
Results
Seven studies (>115,000 subjects) were included in the analyses. A significantly higher risk of AMI (Odds Ratio: 1.03; 95% CI: 1.01-1.06) was observed in the two weeks following spring or winter DST transitions. The risk increase was however significant only after the spring shift (OR: 1.05; 1.02-1.07), while AMI incidence in the week after winter DST transition was comparable to control periods (OR 1.01; 0.98-1.04). No substantial differences by age or gender emerged.
Conclusions
The risk of AMI increases modestly but significantly following DST transitions, supporting the proposal of DST shifts discontinuation. Additional studies fully adjusting for potential confounders are required to confirm the present findings
- …