Direct injection and determination of the active principles of spices using micellar liquid chromatography

In this work, we develop a simple chromatographic method to identify and determine three active principles: curcumin, capsaicin and piperine. These compounds are present as spices in some plants: turmeric (Curcuma longa), red pepper (Capsicum annuum) and black pepper (Piper nigrum). The method includes a micellar mobile phase containing 0.15 M sodium dodecyl sulphate and 12.5% (v/v) propanol buffered at pH 7, a Kromasil C18 column (125 mm × 4.6 mm, 5 μm particle size) and UV detection set at 210 nm. The micellar liquid chromatography (MLC) method herein reported is simple, sensitive, precise, robust, and samples can be directly injected into the column without any pre-treatment step. Under these conditions, analysis times were below 7 min for the complete resolution of the three compounds. Linearity (r > 0.9998), limits of detection of 0.7, 1.3 and 5 ng/mL and limits of quantification of 2, 4.4 and 15 ng/mL, for capsaicin, curcumin and piperine, respectively, intra- and inter-day precision (RSD, %) less than 5.9, were studied in the method validation. Finally, the MLC method was applied to spiked samples, with recoveries of around 100%, and in nine real samples, and with amounts of spices in the 0.02 and 47.1 mg/g range. The simplicity of the method makes it a good candidate to be used in routine analyses in the area of food control and quality.     

Extent of oxidation of Cr(III) to Cr(VI) under various conditions pertaining to natural environment

Calculations show that oxidation of chromium oxide (Cr2O3) by oxygen and oxidation of chromium hydroxide (Cr(OH)3) by manganese dioxide (MnO2) are thermodynamically feasible in both aerobic and mildly anoxic environments. Experiments were carried out to determine the rate and extent of chromium oxidation under various conditions, i.e., when Cr2O3 was heated in the presence of oxygen, when Cr(OH)3 and MnO2 mixtures were suspended in aerobic or anoxic aqueous media at various pH values, when Cr(OH)3 and MnO2 mixtures interacted in moist aerobic conditions and when chromium assumed to be Cr(OH)3 and manganese assumed to be MnO2 interacted in the presence of competing electron donors/acceptors, as is the case in chromium-contaminated sludge. Results indicate that trivalent chromium in Cr2O3 could be readily converted to hexavalent chromium at a temperature range of 200-300 degrees C, with conversion rates of up to 50% in 12 h. In aqueous media, Cr(OH)3 was slowly converted to dissolved Cr(VI) in the presence of MnO2, both in aerobic and anoxic conditions, with conversion rates of up to 1% in 60 days. In moist aerobic conditions and in the presence of MnO2, Cr(OH)(3) slowly converted to hexavalent chromium, with up to 0.05% conversion observed in 90 days. Chromium oxidation also occurred in sludge samples, especially under aerobic conditions. However, such transformation was found to be transitory, with the Cr(VI) formed being ultimately reduced back to Cr(III) due to the presence of various reducing agents in the sludge. Nevertheless since up to 17% conversion of Cr(III) to Cr(VI) occurred in sludge under aerobic conditions by 30 days, there is real danger under field conditions of spreading Cr(VI) pollution due to possible intervening rainfall, runoff and percolation.     

Mechanical and surface properties of corona-treated titanium dioxide-embedded opaque white low-density/Linear low-density polyethylene film

This study encompasses the characterization of corona-treated milky white co-extruded polyethylene films. The surface energies developed at various applied voltages were investigated by standard wetting (dyne) solutions of binary liquid mixtures. A maximum treatment of 40 dynes/cm was achieved at 3.0 kW of the applied load. Maximum heat seal joint strength of 1.05 kN/m was achieved only when an untreated/untreated surface combination was sealed, while a treated/treated surface combination exhibited the minimum heat seal joint strength of 0.98 kN/m. Standard Scotch tape method was employed for testing peel adhesion. An applied load of more than 3.0 kW shows a decreasing trend in surface energy. The coefficient of friction on the treated surface was also investigated. Aging under different environmental conditions had hardly any impact on the treatment levels within the time period under study. A sufficiently opaque (Opacity—99%) white film at Titanium dioxide (TiO₂) loading of 7.5% resulted in a very good barrier film.     

Host-Assisted Delivery of a Model Drug to Genomic DNA: Key Information from Ultrafast Spectroscopy and in silico Study

Drug delivery to a target without adverse effects is one of the major criteria for clinical use. Herein, we have made an attempt to explore the delivery efficacy of SDS surfactant in a monomer and micellar stage during the delivery of the model drug, Toluidine Blue (TB) from the micellar cavity to DNA. Molecular recognition of pre-micellar SDS encapsulated TB with DNA occurs at a rate constant of k₁ ∼652 s⁻¹. However, no significant release of encapsulated TB at micellar concentration was observed within the experimental time frame. This originated from the higher binding affinity of TB towards the nano-cavity of SDS at micellar concentration which does not allow the delivery of TB from the nano-cavity of SDS micelles to DNA. Thus, molecular recognition controls the extent of DNA recognition by TB which in turn modulates the rate of delivery of TB from SDS in a concentration-dependent manner.     

Angiojet™ mechanical thrombectomy-induced hemolysis triggering blood-leak alarms

Blood leak alarms are increasingly rare and may be triggered by rupture of the dialyzer membrane, or intravascular hemolysis. We report two patients who developed hemolysis following Angiojet™ thrombolysis and thrombectomy of thrombosed arteriovenous fistulas, triggering blood leak alarms on hemodialysis, the occurrence of which has not been reported before. AngioJet™-induced hemolysis should be considered in the differential diagnosis for blood leak alarms occurring soon after an intervention on an arterio-venous (AV) fistula.     

Characterization of a Ballard MK5‐E Proton Exchange Membrane Fuel Cell Stack

We present the results of an experimental investigation of the energy balance of a Ballard MK5‐E proton exchange membrane fuel cell (PEMFC) stack. We have investigated the transient phenomena that occur during PEMFC stack warm‐up, under load switching, and when the PEMFC stack is connected to a DC/AC inverter. A simple and convenient model describing the polarization curve as a function of the temperature is presented and validated by our experimental data. We also present experimental results on the increase PEMFC stack performance as a function of the current density for different oxygen concentrations of the oxidant gas.     

Analytical Modeling of Sensitivity Parameters Influenced by Practically Feasible Arrangement of Bio-Molecules in Dielectric Modulated FET Biosensor

Silicon - In this paper, analytical modeling of a Dielectric Modulated Double Gate Field Effect Transistor (DM-DGFET) for biosensing application is presented with extensive data analysis. Firstly,...