A cleaner process for green biodiesel synthesis from waste cooking oil using recycled waste oyster shells as a sustainable base heterogeneous catalyst under the microwave heating system

In this study, biodiesel synthesis from waste cooking oil (WCO) using waste oyster shells derived catalyst (CaO-based catalyst) as a sustainable based heterogeneous catalyst under a microwave heating system technology was investigated. The CaO-based catalysts were characterized by Fourier Transform-Infrared (FTIR), X-ray diffraction (XRD), Electronic Data System (EDS) and Brunauer-Emmett-Teller (BET) measurements. Under optimized conditions, this study has produced tentative results with considerable performances in relations to biodiesel synthesis as follows: (1) the intensification in relation to reaction time from 120 to 180 min has significantly increases the biodiesel yield, which declines with a more intensification to 120 min; (2) the synthesis of biodiesel in this study has proved to increase with an upsurge reaction of power; (3) whereas 180 min reaction time with 800 W microwave power, a methanol-to-oil molar ration of 9:1, a reaction temperature of 65 °C; and 6 wt% catalyst concentration was revealed to be optimal and perfect reaction conditions for this present research work. The highest biodiesel yield was recorded at 87.3% in this study. Whereas the activation energy (E_a) for the catalyzed transesterification reaction was found to be 9.56 kJ/mol. In a nutshell, waste oyster shells were recycled as a sustainable base heterogeneous catalyst to synthesize new biodiesel from WCO, which can be used in diesel engines to address air pollution, especially pollutant emissions from diesel automobiles.     

Study on heterogeneous catalysts from calcined Ca riched hydrotalcite like compounds for biodiesel production

Ca riched Hydrotalcite like compounds (HLCs) were synthesized by co-precipitation method to obtained Ca–Mg–Al mixed metal oxides with a view to produce biodiesel via methanolysis of microalgae. For this purpose, hydrotalcite-like catalysts containing Ca⁺², Mg⁺² and Al⁺³ metals were prepared with a molar ratio (x value) of Al⁺³/(Ca⁺² + Mg⁺² + Al⁺³) at 0.33. Ca/Mg molar ratio in the hydrotalcite like compounds was determined as 0, 0.5, 1, 2. Also, Mg-free CaAl HLCs was prepared at x = 0.33 value. The calcination process was carried out at 800 °C. Obtained catalysts were characterized by BET, XRD, TGA, FTIR, SEM and ICP-OES techniques. The basicity of the all catalysts were investigated by using TPD/CO₂ technique and Hammett indicators. With increase in calcium amount on the HLCs, some evident features were observed such as high basicity and increase in basicity range with H_ values above 15, increase in pore diameter up to 18.37 nm, low pore volume and high catalytic activities. XRD analysis demostrated that the desired Ca–Mg–Al active metal oxide forms were formed after calcination. Catalytic activities of all the catalysts were examined in terms of conversion of microalgae oil to biodiesel and achieved up to 90% FAME yield under mild reaction conditions: 338 K for 5 h, methanol/microalgae oil molar ratio 6:1 and 3% catalyst amount. These results showed that the molar ratio of Ca–Mg in HLCs were significantly effective on the HLCs structure and catalytic activity.     

The role of rehydration in enhancing the basic properties of Mg–Al hydrotalcites for biodiesel production

An Mg–Al hydrotalcite with a Mg/Al molar ratio of 3 was prepared via co-precipitation. The XRD and FTIR analyses proved the presence of the hydrotalcite structure in the uncalcined solid, its destruction after calcination and its reconstruction after rehydration. TG-DSC analyses revealed a higher thermal stability of the rehydrated solids compared to the uncalcined solid. CO₂-TPD analyses showed the presence of stronger and more abundant basic sites for the rehydrated solids. All prepared solids were then tested in the transesterification of sunflower oil [catalyst to oil ratio (CTOR) of 10 wt%, methanol to oil molar ratio (MOMR) of 12:1, temperature of 60 °C and reaction time of 2 h]. The uncalcined and calcined solids all exhibited low activities as evidenced by very low FAME yields (<1.5%). The catalytic activity was significantly improved for most of the rehydrated solids due to their higher basicity. Calcination of the fresh Mg–Al solid at 450 °C followed by subsequent rehydration (Mg₆Al₂-450RH) allowed the obtainment of a FAME yield of 56%. No biodiesel was formed in the presence of the rehydrated catalysts previously calcined at temperatures greater than 500 °C due to a reduced “memory effect”. The effects of reaction conditions such as the duration of rehydration treatment, reaction temperature, MOMR and CTOR on the activity of Mg₆Al₂-450RH were also studied. The obtained results in this work demonstrate the potential of rehydrated Mg–Al solids for biodiesel production. They could also be useful for optimizing the preparation conditions of reconstructed hydrotalcites as basic catalysts and contribute to the search for ideal conditions for biodiesel production.     

Interaction of ouabain with (Na+ + K+)ATPase from human heart and from guinea-pig heart.

(Na⁺ + K⁺)ATPase (ATP phosphohydrolase, EC 3.6.1.3.) has been prepared from human heart and guinea-pig heart, with respective specific activities of 10–15 μmol P_i · mg^?1 · h^?1 and of 25–30 μmol P_i · mg^?1 · h^?1. Residual Mg²⁺—ATPase activities were about 5 per cent. The parameters of (Na⁺ + K⁺)ATPase activity and of ouabain-interaction have been compared: (1) Half-maximal activity concentrations and Hill coefficients of Na⁺, K⁺, Mg²⁺ and ATP were similar for the two species. The apparent activation energies calculated from Arrhenius plots were also similar. A transition was observed at about 23°C. (2) Human heart (Na⁺ + K⁺)ATPase was 10 times more sensitive to ouabain-inhibition than that of guinea-pig. Hunter-Downs plots showed a competitive inhibition for K⁺ at low K⁺ concentration and noncompetitive inhibition at high concentration. (3) The Scatchard plot for [³H]ouabain binding was upward-concave with human heart and linear with guinea-pig heart. (4) The dissociation kinetics of [³H]ouabain from human preparations studied by an isotopic dilution technique indicated two classes of binding sites with k_d of 0.058 min^?1 and 0.0092 min^?1. The dissociation kinetics with guinea-pig heart indicated one single class of binding sites with a k_d of 0.43 min^?1. (5) The time-course of 0.2 μM [³H]ouabain binding showed pseudo-first order association kinetics in man and in guinea-pig. k_a for the two classes of binding sites in man were therefore similar, respectively equal to 3.4 × 10⁶ min^?1 · M^?1 and to 3.7 × 10⁶ min^?1 · M^?1 · k_a for guinea-pig heart was equal to 2.3.10⁶ min^?1 · M^?1. (6) In guinea-pig heart, K_D c from Scatchard plot and from k_d/k_a ratio were equal to the inhibition constant K_i calculated from Hunter-Downs plot indicating that the binding sites were closely related to (Na⁺ + K⁺)ATPase inhibition. (7) In human heart, K_D of the low affinity binding sites was close to K_i, whereas K_D of the high affinity binding sites was several times lower. This suggests that only low affinity binding sites might be involved in (Na⁺ + K⁺)ATPase inhibition by ouabain.     

Industrial worker exposure to airborne particles during the packing of pigment and nanoscale titanium dioxide

Context: Titanium dioxide (TiO2) factory workers’ source specific exposure and dose to airborne particles was studied extensively for particles between 5?nm and 10 μm in size.

Objective: We defined TiO₂ industry workers’ quantitative inhalation exposure levels during the packing of pigment TiO₂ (pTiO₂) and nanoscale TiO₂ (nTiO₂) material from concentrations measured at work area.

Methods: Particle emissions from different work events were identified by linking work activity with the measured number size distributions and mass concentrations of particles. A lung deposit model was used to calculate regional inhalation dose rates in units of particles min^?1 and μg min^?1 without use of respirators.

Results: Workers’ average exposure varied from 225 to 700 μg m^?3 and from 1.15?×?10⁴ to 20.1?×?10⁴ cm^?4. Over 90% of the particles were smaller than 100?nm. These were mainly soot and particles formed from process chemicals. Mass concentration originated primarily from the packing of pTiO₂ and nTiO₂ agglomerates. The nTiO₂ exposure resulted in a calculated dose rate of 3.6?×?10⁶ min^?1 and 32 μg min^?1 where 70% of the particles and 85% of the mass was deposited in head airways.

Conclusions: The recommended TiO₂ exposure limits in mass by NIOSH and in particle number by IFA were not exceeded. We recommend source-specific exposure assessment in order to evaluate the workers’ risks. In nTiO₂ packing, mass concentration best describes the workers’ exposure to nTiO₂ agglomerates. Minute dose rates enable the simulation of workers’ risks in different exposure scenarios.     

Interaction of Hydroflumethiazide and 2,4-Disulfamyl-5-trifluoromethylaniline with Cyclic AMP Phosphodiesterase and Carbonic Anhydrase

Abstract: The inhibitory effect of hydroflumethiazide (HFT) and its metabolite, 2,4-disulfamyl-5-trifluoro-methylaniline (DTA) on cyclic AMP phosphodiesterase and the binding of HFT and DTA to carbonic anhydrase was studied in vitro. Significant inhibition of rat kidney low-K_m cyclic AMP phosphodiesterase was observed with DTA concentration above 2.5 × 10^?4 mol/1 and with HFT concentration above 1 × 10^?4 mol/1. 50% inhibition was observed at a DTA concentration of 1 × 10^?3 mol/1. Binding of DTA and HFT to commercially obtained bovine erythrocyte carbonic anhydrase was demonstrated by equilibrium dialysis. Data were consistent with one class of binding sites. The product of n (number of binding sites) and K_ass (association constant) was 5 × 10⁵ M for DTA and 3.3 × 10⁴ M for HFT at 2°. In human blood in vitro at 37°, the equilibrium erythrocyte/plasma concentration ratio was 18 for DTA and 1.6 for HFT. It is concluded that HFT and DTA have approximately the same potency as cyclic AMP phosphodiesterase inhibitors, whereas DTA is more extensively bound by erythrocyte carbonic anhydrase.     

New catalysts based on reduced graphene oxide for hydrogen production from ammonia decomposition

Promising and highly novel catalysts based on ruthenium (Ru) supported on reduced graphene oxide were synthesized, characterized and tested for CO_x-free hydrogen generation by catalytic ammonia decomposition. Metal loading and amount of a pre-reducing agent clearly affect the catalytic properties of the final catalysts. A Ru loading higher than 2.5 wt% resulted in Ru particles of size higher than 5 nm, which were agglomerated, thus decreasing the amount of the most active sites (B5 type-sites) and therefore the ammonia conversion. Additionally, a graphene oxide (GO) hydrothermal pre-reduction with 2-chloroethylamine hydrochloride, led materials with a more ordered structure which is associated with a good electronic conductivity and, higher basicity. Optimal catalytic activity is achieved using a reducing agent/GO ratio of 5/3 (wt/wt) and a Ru loading of 2.5 wt%. Thus, 2.5Ru/10C-rGO catalyst resulted in excellent hydrogen (H₂) production from ammonia decomposition, with an ammonia conversion close to 96% and hydrogen production rate of 9.1 mmolH₂ g_cat^?1 min^?1 at 400 °C. Reduced graphene oxide proved to be a suitable support in the development of nanosized Ru catalysts being the optimal one highly active in CO_x-free hydrogen generation during more than 60 h of reaction, providing virtuous stability.     

Diffusion Modeling and In Vitro Release Kinetics Studies of Curcumin−Loaded Superparamagnetic Nanomicelles in Cancer Drug Delivery System

The purpose of this study was to investigate in vitro drug release kinetics and to develop diffusion model of curcumin loaded Pluronic F127/Oleic acid(OA)-Fe₃O₄ nanoparticles. The prepared superparamagnetic nanoparticles by co-precipitation technique were characterized by the average size, size distribution, crystallinity, colloidal stability and magnetic property. The release of curcumin was triggered by an acidic environment in pH 5.0 of phosphate buffer saline. Release data of various curcumin loading (15, 25 and 30 ppm) were fitted using non-linear first?order, second?order, Higuchi and Korsmeyer?Peppas model. All the curcumin release mechanism followed Korsmeyer?Peppas model with n values less than 0.45 indicating the Fickian diffusion of curcumin from the prepared nanomicelles. The dynamic of controlled drug release of dilute curcumin loading was well described by a combination of diffusion and first-order release rate. The corresponding diffusion coefficient and kinetic rate were 9.1 × 10^?7 cm²?min^?1 and 6.51 × 10^?7 min^?1, which were used as controlled release to achieve the desired curcumin constant release rate in the delivery system.     

Novel discovery of schisandrin A regulating the interplay of autophagy and apoptosis in oligoasthenospermia by targeting SCF/c-kit and TRPV1 via biosensors

Oligoasthenospermia is the primary cause of infertility. However, there are still enormous challenges in the screening of critical candidates and targets of oligoasthenospermia owing to its complex mechanism. In this study, stem cell factor (SCF), c-kit, and transient receptor potential vanilloid 1 (TRPV1) biosensors were successfully established and applied to studying apoptosis and autophagy mechanisms. Interestingly, the detection limit reached 2.787 × 10⁻¹⁵ g/L, and the quantitative limit reached 1.0 × 10⁻¹³ g/L. Furthermore, biosensors were used to investigate the interplay between autophagy and apoptosis. Schisandrin A is an excellent candidate to form a system with c-kit similar to SCF/c-kit with a detection constant (K_D) of 5.701 × 10⁻¹¹ mol/L, whereas it had no affinity for SCF. In addition, it also inhibited autophagy in oligoasthenospermia through antagonizing TRPV1 with a K_D of up to 4.181 × 10⁻¹⁰ mol/L. In addition, in vivo and in vitro experiments were highly consistent with the biosensor. In summary, high-potency schisandrin A and two potential targets were identified, through which schisandrin A could reverse the apoptosis caused by excessive autophagy during oligoasthenospermia. Our study provides promising insights into the discovery of effective compounds and potential targets via a well-established in vitro-in vivo strategy.     

Intracellular disposition of arabinogalactan and asialofetuin in HepG2 cells

The binding and uptake of arabinogalactan and asialofetuin in HepG2 cells was kinetically characterized using ^I25I-labeled ligands. The number of binding sites (n) and the association constant (K) of arabinogalactan was 1.9 × 10⁵ ± 1.2 × 10⁵ sites/cell and 5.0 × 10⁶ ± 3.9 × 10⁶ M^? 1, respectively, whereas the n and K_a of asialofetuin was 2.7 × 10⁵ ± 1.1 × 10⁵ sites/cell and 1.1 × 10⁷ ± 0.7 × 10⁷ M^? 1, respectively. These results suggest that the binding capacity of HepG2 cells for arabinogalactan is lower than that for asialofetuin. Moreover, the amount of arabinogalactan uptake by HepG2 cells was lower than that of asialofetuin. Thus, asialofetuin was preferentially bound and internalized by hepatoma cells compared to arabinogalactan.     

Solvent-free K–CaO/Ca(OH)2 mixed-phase nanocatalytic single-step methanolysis,ethanolysis and aminolysis of Pongamia pinnata triglycerides

In this report, the K–CaO/Ca(OH)₂ mixed-phase nanodendrites were prepared and used as a heterogeneous catalyst for the one-pot solvent-free synthesis of methyl esters, ethyl esters and alkyl amides from Pongamia pinnata triglycerides. A modified incipient-wetness chemical impregnation method was used to prepared potassium hydroxide doped CaO, MgO, and ZnO nanocrystallites. The prepared K–CaO/Ca(OH)₂ nanocrystallites were found as the most efficient heterogeneous catalyst (4%, w/w) for aminolysis (6:1 M ratio of diethanolamine/oil, 110 °C), methanolysis (9:1 M ratio of methanol/oil at 65 °C) and ethanolysis (9:1 M ratio of ethanol/oil at 75 °C) of Pongamia pinnata oil and took 40 min for the completion (99% yield) of all the reactions. The K–CaO/Ca(OH)₂ nanodendrites were found to be efficient at room temperature (25–30 °C) also and reused for 10 reaction cycles. The pseudo-first-order reaction kinetic model was applied and the first-order rate constant was calculated as 0.112 min^?1, 0.093 min^?1, and 0.118 min^?1 for the methanolysis, ethanolysis, and aminolysis of Pongamia pinnata oil, respectively.     

Plasma pharmacokinetics and urinary and biliary excretion of a new potent tripeptide HIV-1 protease inhibitor,KNI-272, in rats after intravenous administration

The pharmacokinetic (PK) characteristics of KNI-272, a potent and selective HIV-1 protease inhibitor, were evaluated in rats after intravenous (IV) administration. The effect of dose on KNI-272 plasma kinetics, and the urinary and biliary elimination kinetics of KNI-272, were examined. After IV administration of 10.0 mg kg^?1 KNI-272, the mean terminal elimination half-life, t_1/2λz, was 3.49 ± 0.19 (SE) h, the total plasma clearance, CL_tot, was 15.1 ± 1.2 mL min^?1 and the distribution volume at steady state, V_d,ss, was 3790±280 mL kg^?1. On the other hand, after 1.0mg kg^?1 IV administration, t_d,ss, was 3.04±0.11 h, CL_tot was 15.9±0.2mL min^?1, and V_d,ss was 6950±600 mL kg^?1. The PK parameters of KNI-272 after IV administration showed that the disposition of KNI-272 in the rat plasma is linear within the dose range from 1.0 to 10.0mg kg^?1. Using an equilibrium dialysis method, the plasma binding of KNI-272 was measured in vitro. The free fractions were 17.7 ± 0.6%, 12.1±1.5%, and 13.8 ± 1.4% at the total concentration ranges of 9.898 ± 0.097 μg mL^?1, 0.888 ± 0.008 μg mL^?1, and 0.470±0.55 μg mL^?1, respectively. The percentages of the dose excreted into the urine and bile as the unchanged form were 1.20 ± 1.06% and 1.61 ± 0.32% at 1.0mg kg^?1 dose, and 0.164 ± 0.083% and 1.42 ± 0.26% at 10.0 mg kg^?1 dose, respectively. The renal clearance (CL_R) and the biliary clearance (CL_B) were calculated to be 0.191 and 0.256mL min^?1 for 1.0mg kg^?1, and 0.0248 and 0.215 mL min^?1 for 10.0 mg kg^?1, respectively. When comparing these values with the CL_tot values, the urinary and biliary excretion of KNI-272 are minor disposition routes.     

Insight into the sulfonation conditions on the activity of sub-bituminous coal as acidic catalyst during the transesterification of spent corn oil; effect of sonication waves

The impact of the sulfonation conditions on the catalytic activity of coal as an acidic catalyst was assessed by normal stirring (NS.Coal) and sonication waves (SS.Coal) based on the Response Surface methodology. The NS.Coal exhibits acid density and surface area of 8.8 mmol/g and 27.8 m²/g, respectively. This was obtained after 90 min at sulfonation conditions of 150 °C temperature and 95% H₂SO₄ concentration. In the existence of sonication waves for 60 min (240 W), SS.Coal shows acid density and surface area of 14.2 mmol/g and 45.8 m²/g, respectively. This demonstrates significant efficiency for the sonication-induced sulfonation processes during the synthesis of sulfonated coal as an acidic catalyst. The activities of NS.Coal and SS.Coal acidic catalysts were evaluated during the transesterification of corn oil. The best yield was obtained by NS.Coal (4 wt, %) is 99.3% after 60 min at 60 °C in the presence of 14:1 methanol/oil ratio. The archived yields using SS.Coal at loading values of 2 wt, %, 3 wt, %, and 4 wt, % are 99.6%, 99.84%, and 99.85%, respectively after 20 min. The kinetic properties of reactions were illustrated based on the Pseudo-First order assumption. The thermodynamic studies demonstrate the endothermic properties of the corn oil transesterification reactions. The determined activation energy by NS.Coal and SS.Coal are 26.22 kJ/mol and 17.7 kJ/mol, respectively reflect the possible use of them as effective catalysts at low energy and mild conditions.     

Potentiometric monitoring of cobalt in beer sample by solid contact ion selective electrode

A new solid contact cobalt selective electrode was constructed with 4-tert-butylthiacalix[4]arene as ionophore. The best performance was observed with the membrane having an ionophore/polyvinyl chloride/sodium tetraphenylborate/nitrophenyl octyl ether ratio of 3.5:33:1.5:62 (w/w; mg). The electrode, under steady-state conditions, exhibited a working concentration range of 1 × 10⁻¹ – 1 × 10⁻⁶ mol/L with a near-Nernstian slope of 25.3 mV/decade and a detection limit of 3.5 × 10⁻⁷ mol/L. The electrode had a very short response time (<10 seconds) and good reproducibility at a working pH range of 4.0–6.5. The electrode was used for 4 months without any significant change in its sensitivity. The potentiometric performance of the electrode in partially nonaqueous medium [up to 20 % (v/v) alcohol] was found satisfactory. The performance of the prepared electrode for the analysis of beer samples using direct potentiometric method is very encouraging.     

Effects of length of exposure to and concentration of acetaldehyde on the release of catecholamines

The perfused isolated cow adrenal gland was stimulated to release catecholamines by perfusion with Tyrode solution containing acetaldehyde in concentrations between 1.5 × 10^?5 and 2.5 × 10^?2 M. Release per unit time (μmoles/min) of catecholamines by acetaldehyde increased as the length of exposure to the drug was increased. In contrast to carbachol, the concentration-response curve for acetaldehyde was shifted to the left by increasing the stimulation time 3-fold. A delay in reaching the maximum response was observed at 2 × 10^?3 M acetaldehyde; this delay increased as the concentration of acetaldehyde was lowered. Catecholamine release returned to its basal level upon terminating the infusion of acetaldehyde. It is concluded that acetaldehyde can release adrenal catecholamines at concentrations similar to those that occur in man after ingestion of alcohol, but a period of time is required for accumulation of an effective concentration of the drug at its site of action.     

The pharmacokinetics of orally administered S-carboxymethyl-l-cysteine in the dog,calf and sheep

The aim of this study was to investigate the feasibility of employing S-carboxymethyl-l-cysteine as a treatment of chronic obstructive pulmonary disease in dogs. To this end the pharmacokinetic parameters of orally administered S-carboxymethyl-l-cysteine were determined in the dog, cow and sheep. Six healthy beagle dogs, six endogenous Greek sheep and four Holstein Fresian calves were orally dosed with 10 mg/kg body weight of S-carboxymethyl-l-cysteine. No significant differences in T_max and T_1/2 were reported between the species. However, significantly higher AUC_(0–last), 21.56 ± 6.67 μg h ml^?1 and AUC_(0–∞), 21.63 ± 6.68 μg h ml^?1 were seen in the dogs compared to the sheep and calves. The calculated V_D was significantly higher in the sheep (10.4 ± 2.7 L kg^?1) and the calves (3.8 ± 0.7 L kg^?1) compared to the dogs (1.0 ± 0.6 L kg^?1). The rank order of increasing C_L was sheep (3.4 ± 2.7 L h^?1 kg^?1) > calves (2.7 ± 0.4 L h^?1 kg^?1) > dogs (0.5 ± 0.2 L h^?1 kg^?1). The result for the dogs was significantly lower that the calculated C_L for the sheep and calves.All these results indicate that the oral administration of S-carboxymethyl-l-cysteine may be useful during the therapeutic management of chronic obstructive pulmonary disease in dogs.     

Role of NO-synthases and cyclooxygenases in the hyperreactivity of male rabbit carotid artery to testosterone under experimental diabetes

Cardiovascular disease is the major cause of morbidity and mortality in diabetic patients, which in turn is also associated with low levels of serum testosterone. The working hypothesis was that diabetes might modify the mechanisms involved in the vascular actions of testosterone in isolated rabbit carotid arteries. Testosterone (10^?8–3 × 10^?4 M) induced a concentration-dependent relaxation of precontracted carotid arteries, which was higher in diabetic than in control rabbits. In control rabbits neither endothelium removal nor the nitric oxide synthase (NOS) inhibitor N^G-nitro-l-arginine (l-NOArg, 10^?5 M) modified the relaxant action of testosterone, and the cyclooxygenase (COX) inhibitor indomethacin (10^?5 M) enhanced this relaxation. In contrast, in diabetic rabbits endothelium removal, l-NOArg (10^?5 M) or indomethacin (10^?5 M) inhibited the testosterone induced relaxation. In arteries from diabetic rabbits, eNOS, iNOS and COX-2 expression and testosterone induced release of prostacyclin resulted enhanced in comparison with arteries from control rabbits. Testosterone (10^?4 M) strongly inhibited CaCl₂ (10^?5–3 × 10^?2 M) concentration-related contractions of the carotid artery both in control and diabetic rabbits. These results suggest that testosterone relaxes the rabbit carotid artery by blocking the extracellular calcium entry. Diabetes enhances the vasodilator response of the rabbit carotid artery to testosterone by a mechanism that at least includes an increased modulatory activity of the endothelial nitric oxide and an augmented release of COX-2 vasodilator, prostacyclin rather than the absence of COX-1 vasoconstrictor, thromboxane A₂. The hypotestosteronemia observed in diabetic rabbits could be a consequence of the increased expression of iNOS and could contribute to the hyperreactivity of the rabbit carotid artery to testosterone.     

A synergistic framework for development of green HPLC methods for determination of amlodipine besylate and candesartan cilexetil in presence of their hydrolytic degradation products in two different matrices

The world is changing so fast towards rationalization of resources consumption and employing safer practices for the surrounding environment and humans. Therefore, there is a renewed interest in integrating green analytical chemistry principles and experimental design methodologies for screening and optimizing complex analytical procedures such as HPLC. Thus, this work introduces three sustainable versatile multi-analyte HPLC methods with two types of detection techniques. Firstly, amlodipine besylate and candesartan cilexetil with three of their hydrolytic products were chromatographed on CSH-C₁₈ (150 mm) stationary phase within short run time (about 8.9 min) through gradient elution mode, flow rate 1 mL min^?1 and UV-detection at 210 nm and 254 nm. Face-centered composite design and Derringer's desirability function were implemented to optimize the chromatographic conditions to fit the goals of pharmaceutical and biological analysis via fluorometric detection. A good separation was obtained utilizing HSS-Cayno (250 mm) column and mobile phase composed of ethanol and phosphate buffer, pH 3.5, (55.6: 44.4, v/v) delivered at 1.03 mL min^?1 at 245 and 446 nm as excitation and emission wavelengths, respectively, with quantification range of 1.00–400.00 ng mL^?1 for amlodipine and 1.00–600.00 ng mL^?1 for candesartan cilexetil. The conditions were modified for plasma analysis to a new ratio (45:55, v/v) pH 3.7 and flow rate 0.7 mL min^?1. The methods' greenness profiles have been evaluated and compared with the reported ones via several comprehensive tools.     

Membrane lesions in cultured mouse neuroblastoma cells exposed to metal compounds

Tritiated 2-deoxy-D-glucose (dGlc) was rapidly taken up into cultured mouse neuroblastoma C1300 cells (clone 41A₃). Upon perfusion the pre-loaded cultures slowly released radioactivity as [³H]2-deoxy-D-glucose-6-phosphate ([³H]dGlc-6-P) (rate const. = 0.017 min^?1) from a pool corresponding to 74% (t1/2 = 41 min) of the total radioactivity incorporated. Destruction of the plasma membrane of the cells by means of Triton X-100 (1.0%) resulted in a rapid and total release of the radioactivity. CH₃HgCl, HgCl, (C₂H₅)₃SnCl and K₂Cr₂O₇ all caused an increase in the passive cell membrane permeability to [³H]dGlc-6-P. A membrane toxic concentration (MTC) was defined as the concentration of the tested metal compound giving rise to an increase in the relative efflux from 1.0 to 1.2 during 60 min perfusion. Using this MTC-value, the membrane toxicity of the compounds could be ranked in the following order: CH₃HgCl (MTC = 9 × 10^?7 M >; HgCl (MTC = 6 × 10^?6 M) > (C₂H₅)₃SnCl (MTC = 3 × 10^?4 M) > K₂Cr₂O₇ (MTC = 7 × 10^?4 M. Since this differential toxicity is in accordance with other reports it is concluded that 2-deoxy-D-glucose (dGlc) may be used together with 41A₃ cells to screen metal compounds for their membrane toxicity.     

Aqueous nitrate ion adsorption/desorption by olive solid waste-based carbon activated using ZnCl2

ZnCl₂ activated carbon (ZnCl₂-AC, with specific surface area ~1480 m²/g) effectively adsorbs nitrate from water with uptake capacity (~5.5 mg/g) four-fold that for other commercial activated carbons (CACs). Kinetics show a small activation energy value (~7 kJ/mol) consistent with a diffusion-controlled process. This is further confirmed by intra-particle diffusion study. Negative thermodynamic parameters (ΔH° ?13.859 kJ/mol, ΔS° ?43.8 J/mol K, and ΔG° ?0.808 kJ/mol) indicate spontaneous nitrate adsorption. The high specific surface area rationalizes the high uptake capacity for the ZnCl₂-AC. A Langmuir type adsorption, is observed. ZnCl₂-AC effectively adsorbs the nitrate from water, even at high concentrations, and brings the concentration to allowed maximum values. Despite these advantages, the ZnCl₂-AC exhibits low desorption (~20%) of pre-adsorbed nitrate ions into concentrate solutions. Up to ~40% desorption is observed by grinding the pre-saturated ZnCl₂-AC. Developing other methods to completely recover the adsorbed nitrate and the adsorbent for multiple use is needed.