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Introduction: Nowadays, the management of drug effluents, as emerging pollutants, has attracted great attention due to human health and ecological adverse effects. During the COVID-19 pandemic, two drugs, Fexofenadine and Montelukast, have been used in large quantities for patients with lung involvement. The aim of this study is to investigate the feasibility of removing Fexofenadine and Montelukast and determine the removal kinetics. Material and Methods: In this study, we used Rhodotron accelerator to determine kinetic coefficients for the removal of drugs. Our research focused on studying the kinetics of E-Beam radiation reactions and the generation of significant amounts of free radicals during these processes. We employed first-order and second-order kinetic models under laboratory conditions, taking into account various influencing factors to establish the rate of removal. Results: The results showed that the decomposition of Fexofenadine and Montelukast drugs by high-energy E-Beam bending process is a pseudo-first-order reaction with a coefficient of more than 0.9105 and 0.998, respectively. The results showed that the reaction rate constant depended significantly on the initial concentration of Fexofenadine and Montelukast drugs and their molecular structure. Conclusion: Using a Rhodotron accelerator is important for removing Fexofenadine and Montelukast from the aquatic environment.

In this study, scandium and lithium extractions were investigated using the atmospheric pressure agitation leaching method at acidic medium. The leaching tests were carried out at two stages. To remove the ionic impurities such as Na and Al first stage leaching was performed at relatively higher pH. Following solid-liquid separation of leach cake of the first stage leaching, it was subjected to the second stage leaching. The second stage leaching resulted in 95.1% Sc and 94.7% Li extractions. The overall Sc and Li recoveries were determined as 82.4% and 86.5%, respectively. Regarding the kinetic studies, it was understood that scandium and lithium leaching processes were controlled by a combination of chemical reaction and ash diffusion models. In this case, the activation energies were determined as 29.52 and 30.22 kJmol-1, respectively for scandium and lithium. As a result, while direct H2SO4 leaching of red mud is a challenge due to physical and chemical problems, an alternative solution was suggested using H2SO4

Summary: In this study, the pyrolysis products formation and kinetics of base cracked oil were studied by a TG-FTIR device, which can provide a reference basis for heavy oil and gas reaction and industrial application. The results exhibited that the saturated fraction was mainly composed of chain alkanes and cycloalkanes. The aromatic fraction mainly contains polycyclic aromatic hydrocarbons and alkyl substituted aromatic hydrocarbons. The resin fraction is mainly multi-cyclic aromatic hydrocarbons. As the fraction becomes heavier, the initial and termination cracking temperature of saturate, aromatic, the amount of carbon residue gradually increases and coking intensifies. The pyrolysis products of chemical group were mainly methane, ethylene, C2+ hydrocarbons, and light aromatics, and the main contributing components for the generation of low carbon olefins are the saturated and aromatic fractions. The correlation coefficients R2 of the linear equations and fitting results were close to 1, and thus proving that the selected model was reasonable. The saturate fraction had the lowest activation energy of 78.82 kJ·mol-1, while the aromatic, resin, and asphaltene have activation energies of 103.46 kJ·mol-1, 108.87 kJ·mol-1, and 110.56 kJ·mol-1, respectively. [ABSTRACT FROM AUTHOR]

Patrícia Faria Camargo,1 Luciana Ditomaso-Luporini,1 Luiz Carlos Soares de Carvalho Jr,2 Cássia da Luz Goulart,1 Rayane Sebold,1,3 Polliana Batista dos Santos,1 Meliza Goi Roscani,4 Audrey Borghi–Silva1 1Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of Sao Carlos, Sao Paulo, Brazil; 2Center for Science and Technology in Energy and Sustainability of Federal University of Reconcavo da Bahia, Feira de Santana, Bahia, Brazil; 3Course of Physiotherapy, Central Paulista University Center, Sao Carlos, Sao Paulo, Brazil; 4Medicine Department, Federal University of Sao Carlos, Sao Carlos, Sao Paulo, BrazilCorrespondence: Audrey Borghi–Silva Email audrey@ufscar.brBackground: The heart rate (HR) kinetics as well as other predictors of functional capacity such as the Chronic Obstructive Pulmonary Disease (COPD) Assessment Test (CAT), the Duke Activity Status Index (DASI) and the handgrip strength (HGS) represent important tools in assessing the impact of COPD on exercise performance and health status of individuals with COPD.Purpose: To verify the relationship between functional capacity, measured using the six-minute walking test (6MWT), with the HR off-kinetics, HGS and the DASI and CAT scores.Methods: For this cross-sectional study, 29 subjects with COPD underwent body composition, pulmonary function and cardiac function tests. Subsequently, the DASI and CAT questionnaires and HGS test were performed. The beat-to-beat R-R intervals (IRR) were collected in rest, during the test and in recovery after the 6MWT. The HR off-kinetics was obtained during a 360-second period in post-exercise recovery through the HR mono-exponential decay.Results: Moderate correlations were observed between: 1) walked distance (WD) in the 6MWT and the CAT and DASI scores (r= − 0.58, p=0.001 and r= 0.58, p=0.001, respectively); 2) WD and HGS (r=0.37, p=0.05); 3) and WD and HR off-kinetics (τ; r= − 0.54, p=0.002 and MRT; r= − 0.55, p=0.002, respectively).Conclusion: The 6MWT performance is a direct measurement to evaluate functional capacity. Additionally, it is related to other direct and indirect markers for functional evaluation in patients with COPD. These results suggest the application of these tools in clinical practice, based on the accessibility, non-invasive character and easy applicability of these methods.Keywords: COPD, questionnaires, exercise, kinetics

Introduction: Prolyl-specific oligopeptidase (POP), one of the brain's highly expressed enzymes, is an important target for the therapy of central nervous system disorders, notably autism spectrum disorder, schizophrenia, Parkinson's, Alzheimer's disease, and dementia., Method: The current study was designed to investigate 2,4-bis(trifluoromethyl) benzaldehyde- based thiosemicarbazones as POP inhibitors to treat the above-mentioned disorders. A variety of techniques, such as nuclear magnetic resonance (NMR), mass spectrometry (MS), and Fourier-transform infrared spectroscopy (FTIR), were used for the structural confirmation of synthesized compounds. After in-vitro evaluation, all of these compounds were found to be prominent inhibitors of the POP enzyme (IC50= 10.14 - 41.73 μM)., Result: Compound 3a emerged as the most active compound (IC50 10.14 ± 0.72 μM) of the series. The kinetic study of the most active 3a (Ki =13.66 0.0012 μM) indicated competitive inhibition of the aforementioned enzyme., Conclusion: Moreover, molecular docking depicted a noticeable role of thiosemicarbazide moiety in the binding of these molecules within the active site of the POP enzyme., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The aim of this study was to address the modeling of aspects such as weight reduction (WR), solid gain (SG) and weight-loss (WL) in Caribbean pumpkin samples osmotically dehydrated in ternary solutions. For this purpose, osmotic dehydration was carried out using two ternary solutions: stevia-salt-water (S1) and glucose-salt-water (S2) at different concentrations (20%, 30% and 40% w/w), and processing times of 40 min, 80 min, 120 min, and 160 min. Also, the diffusion coefficient was determined and the analysis of variance with orthogonal polynomials was performed to find the best treatment for dehydration of auyama samples (p≤0.05). The results suggest that the solution constituted by stevia-salt-water, allows greater reduction of weight and gain of solids when a concentration of 40% is used at a time of 78.12min until reaching a humidity percentage of 60.06%. Similarly, the values of the diffusion coefficient for this solution ratify that the increase in concentration generates less resistance to mass transfer.

Conversion calcium carbonate is a by-product of manufacturing mineral fertilizers, i.e. NAP fertilizer. It needs further processing and grinding to be used as a fi ller for polymeric materials. The choice of equipment and the fi nal degree of grinding depend on the kinetic characteristics of the process. The aim of the work is to study the mechanism and kinetics of chemically-deposited calcium carbonate grinding. The feedstock was ground by means of a laboratory vibratory mill for 30 minutes, a sample was taken every minute to study the fractional composition and the speed of the process. It was determined that the most intensive processing takes place during the fi rst minute of grinding (t = 0–1 min), the maximum grinding speed is reached for fractions of +50–75 μm, +75–100 μm, and +100–150 μm and are 14.5 %/min, 13.5 %/min and 17.5 %/min respectively. Particles predominantly fall into the grade of –5 μm, and, to a lesser extent, into the classes +5–10 μm, +10–20 μm, and +20–30 μm, resulting in a bimodal distribution. With an increase in processing time by more than 5 minutes, the agglomeration of particles occurs, the size of which ranges 10-30 μm. The grinding kinetics of the chemically-deposited calcium carbonate obeys the rules of a fi rst-order equation. A linear relationship is observed between the relative content of the unground fractions ln[Rd(t) / Rd(0)] and the grinding time t. The specifi c grinding speed of conversion calcium carbonate increases signifi cantly with an increase in particle size.

Copper‐based catalyst was applied in the condensed diester hydrogenation with unexpected high selectivity (∼100 %) to 1,6‐hexanediol. On basis of the mass transfer analysis and kinetics results, the reaction rate of the condensed diester hydrogenation was deduced to be controlled by the activation of hydrogen on Cu0 sites, which was further demonstrated by the correlations between the catalytic activity and different copper species. Importantly, this catalysis mechanism is different with that of gas‐phase diester hydrogenation, which is generally determined by the adsorption of ester on Cu+ species. [ABSTRACT FROM AUTHOR]

Background: This research studied the effect of UV light on pentachlorophenol (PCP) removal in the electro-Fenton (EF) process. Methods: PCP was used as the pollutant in this study. The effects of Fenton’s reagent, i.e. hydrogen peroxide concentration, solution pH, and treatment time by EF (EF) and photoelectro-Fenton (PEF) processes, were studied to determine rates of PCP removal. The results showed that a better performance and a high removal efficiency were achieved by coupling UV radiation and the EF process. Results: EF processes required more time to remove PCP, while after a reaction time of 10 minutes, the PEF achieved a removal efficiency of 90.4%; this value is higher than the maximum efficiency of the EF process (83.44% after 40 minutes). The kinetic mechanisms of both processes were examined and compared. The rate constants at optimum conditions were 0.0455 and 0.0579 min−1 for EF and PEF processes, respectively. Conclusion: Removal efficiency was obtained in the order of PEF > EF.

The parametric statistical adsorption of chemically unmodified coconut shell powder (CSP) to adsorb iron (II) ions from aqueous solutions was examined in this work. It was observed that the adsorption capacity increased with increasing adsorbent dose, reducing adsorbate dose, increasing contact time, decreasing temperature and reducing particle size. As observed about one gram of the adsorbent was sufficient enough to remove 98 % iron (II) ions. A total contact time of about 40 minutes was sufficient for almost complete adsorption of the ions, while a pH of about 6.0 exhibited the maximum adsorption capacity. The sorption data were fitted into Langmuir, Freundlich, Temkin and the Dubinin-Radushkevich isotherms, fitted most with the Freundlich Isotherm model. The energy values obtained from the Temkin and Dubinin-Radushkevich isotherm model indicated high chemisorption phenomenon with the adsorbents. Investigation of some kinetic models confirmed that the adsorption of iron (II) ions using CSP was a pseudo-second order kinetic process, which further corroborates that chemisorption dominates the adsorption. Fourier Transform Analysis (FTIR) further established and justified the outcome of the study. The adsorption was parametrically justified statistically with Analysis of Variance (ANOVA) and Bonferroni-Holm Posthoc significance test. Conclusively, coconut shell proved strongly to be an effective and suitable adsorbent for removing iron (II) ions from aqueous solutions.

Background: in Colombia the consumption of fresh green mango (also known as mango “biche”) is quite popular, and is consumed with lemon juice, salt, and honey. However, its high humidity content and high water activity makes of mango a highly perishable fruit, thus requiring processing alternatives. Osmotic dehydration (OD) is an interesting alternative for the conservation of mango. In OD, binary solutions (Solute + water) and ternary solutions (2 Solutes + water), have been traditionally used, however, more water removal can be achieved using ternary solutions, which leads to the improved organoleptic properties of dehydrated products. Objetives: to evaluate the kinetic water loss (WL), solutes gain (SG), weight reduction (WR), water activity (aw), and volume (Shrinking Coefficient, SC) in green mango (Mangifera indica L. Filipino variety) osmotically dehydrated (OD). Additionally, to calculate water and solutes diffusivity (Def ) for each treatment. Methods: green mango samples, with maturity scale zero, were used. Ternary solutions of sucrose at 40% and NaCl at 3, 6 and 9% were used for OD. The binary solution of sucrose with water as control treatment, was used. In the osmotic process samples were taken out at different times of OD (15, 30, 60, 90, 180, 240, and 300 min). Results: the findings show that at a higher concentration of NaCl, the dehydration kinetics was more rapid, aw and SC were smaller and water and solutes Def were higher. The samples dehydrated with the greatest solutes concentration (40-9%) reached the highest WL, SG, and WR with 89.52, 13.10, and 46.68%, respectively. Coefficients Defw and Defs showed a magnitude order of 10-10 m2/s, which is within the interval of dehydrated foods. Conclusions: this research showed that binary (sucrose + water) and ternary (NaCl + sucrose + water) solutions, are suitable for dehydrating green mango, however, the ternary solutions were more effective.

Background: The goal of this work was to synthesize and fabricate matrix type transdermal patches based on a combination of polymers (Eudragit L100, HPMC and PVP K30), plasticizer and crosslinking agents (propylene glycol and triethyl citrate) and adhesives (Dura Tak 87-6908) to increase Thiocolchicoside (THC) absorption via topical route. This method allows avoidance of first-pass metabolism along with a consistent and extended duration of therapeutic activity., Methods: Fabrication and casting of polymeric solutions containing THC was done either in petri plates or through lab coater to get transdermal patches. Finally, the formulated patches were studied for their physicochemical and biological evaluation using scanning electron microscopy, FTIR, DSC, XRD and ex-vivo permeation studies using pig ear skin., Results: FTIR studies confirm that the THC characteristics peaks (carbonyl (Amide I) at 1525.5 cm -1 , C=O stretching (tropane ring) at 1664.4 cm -1 , Amide II band (N-H stretching) at 3325.9 cm -1 , thioether band at 2360.7 cm -1 , and OH group stretching band at 3400.2 cm -1 ) are still present in the polymer mixture even after formulation as a transdermal patch, indicating compatibility among all excipients. While on the other hand, DSC studies confirm endothermic peaks for all the polymers along with THC with the highest enthalpy of 65.979 J/g, which is an indicator of sharp endothermic peak at 198°C, leading to the melting of THC. The percentage drug content and percentage moisture uptake of all the formulation was found in the range of 96 ± 2.04 to 98.56 ± 1.34% and 4.13 ± 1.16 to 8.23 ± 0.90%, respectively. Drug release and release kinetics studies confirm that it is dependent on the composition of individual formulation., Conclusion: All these findings support the possibility of using suitable polymeric composition, as well as proper formulation and manufacturing circumstances, to create a one-of-a-kind technology platform for transdermal drug administration., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

This research article deals with an electrosynthesis of hydrous titanium dioxide by anodic dissolution of titanium sacrificial anodes and their application for the adsorption of manganese from aqueous solution. Titanium sheet was used as the sacrificial anode and galvanized iron sheet was used as the cathode. The optimization of different experimental parameters like initial ion concentration, current density, pH, temperature, etc., on the removal efficiency of manganese was carried out. The maximum removal efficiency of 97.55 % was achieved at a current density of 0.08 A dm-2 and pH of 7.0. The Langmuir, Freundlich and Redlich Peterson isotherm models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The adsorption of manganese preferably followed the Langmuir adsorption isotherm. The adsorption kinetics was modelled by first- and second- order rate models and the adsorption kinetic studies showed that the adsorption of manganese was best described using the second-order kinetic model. Thermodynamic parameters indicate that the adsorption of manganese on hydrous titanium dioxide was feasible, spontaneous and exothermic.

The aim of this work was to thermally characterize the renewable lignocellulosic bioresources derived from palm trees in order to highlight their energy potential. Pyrolysis and combustion behaviours of date stones (DS) agricultural by-products were tested by thermo-gravimetric analysis, and the main chemical compositions were analyzed. The work has also been conducted to identify their most important physical characteristics. The study of the sizes and heating rate effects constitute the first part of the experimental work. Inert atmosphere and three heating rates: 10, 20, and 50 °C/min, were applied to various particle sizes of DS. In the second part, tests were carried out in an oxidizing atmosphere (21% O2) by varying the size of the DS. The kinetic parameters such as pre-exponential factor and activation energy were determined. Increasing the particle sizes and the heating rates didn’t have an appreciable influence on the global weight losses. However, degradation rates were significant with the porous structure of the DS. Weight losses in inert and oxidizing atmospheres were found to occur in two stages (drying and devolatilization) and in three stages (drying, devolatilization, and oxidation of the char).

Hydrogen sulfide removal catalyst was prepared chemically by precipitation of zinc bicarbonate at a controlled pH. The physical and chemical catalyst characterization properties were investigated. The catalyst was tested for its activity in adsorption of H2S using a plant that generates the H2S from naphtha hydrodesulphurization and a unit for the adsorption of H2S. The results comparison between the prepared and commercial catalysts revealed that the chemical method can be used to prepare the catalyst with a very good activity.It has observed that the hydrogen sulfide removal over zinc oxide catalyst follows first order reaction kinetics with activation energy of 19.26 kJ/mole and enthalpy and entropy of activation of 14.49 kJ/mole and -220.41 J/mole respectively.

This research was conducted to study the feasibility of using fruit peels as biosorbent for removal of Pb+2, Cu+2 and Zn+2 ions from simulated wastewater. A waste biomass of Pomegranate Peel or Punicagranatum L. (P. granatum L.) was chosen as neutral biosorbent in this study.Fourier transformation infrared (FTIR) was used to characterize the surface of PGP, the results confirm that amino, carboxylic, hydroxyl and carbonyl group on the surface of PGP. Different parameters such as initial concentration range between (25-200) mg/L, pH (3-7), contact time (1-2) hour, amount of sorbent (0.1- 4) gm, agitation speed range (200- 500) rpm and temperature (25- 50oC), influencing the sorptive process were examined. Sorption equilibrium isotherm and kinetic data fit well by the Langmuir isotherm and the pseudo-second-order kinetic model, respectively. Sorption processes were spontaneous and exothermic in nature according to the thermodynamic results and the equilibrium was attained within 60 minute. The amount of sorbed metal ions was calculated as 9.9, 9.5 and 7.75 mg/g dry PGP for Pb+2, Cu+2 and Zn+2ions, respectively, at pH 5; temperature 25oC; contact time 1hr and 4 gm of peels.

In this study, we have reported the removal of Cr(VI) ions by polyaniline (PANI) particles from aqueous medium. PANI in its emeraldine salt (ES) form can interact with Cr(VI), which is present as $\text {HCrO}_{\text {4}}^{\boldsymbol {-}} $ in two ways. The adsorption of $\text {HCrO}_{\text {4}}^{\boldsymbol {-}} $ ions due to the electrostatic interaction between partially positively charged PANI backbone and Cr(VI) anions causes the major portion of Cr(VI) removal and a small portion of Cr(VI) is reduced to Cr(III) by PANI (ES). The adsorption follows Langmuir adsorption isotherm and second-order kinetic model. It is observed that the removal of Cr(VI) is negligibly effected by the presence of other anions in the aqueous medium. The adsorption capacity of PANI (ES) is found to be 123 mg g, which is very high compared to activated carbon-based materials. The adsorbed anions can be desorbed by converting PANI emeraldine salt (ES) to PANI emeraldine base (EB). The EB form of PANI can be converted into ES form by treating with acid, which can be reused as adsorbent. It is important to note that the PANI (ES) is oxidized by $\text {HCrO}_{\text {4}}^{\boldsymbol {-}} $ ions which decrease the hydrophilicity of the surface of PANI particles. This causes the decrease in adsorption capacity of recycled PANI. [ABSTRACT FROM AUTHOR]

In the present study, superabsorbents (SAPs) of cationic monomer [2-(methacryloyloxy) ethyl] trimethylammonium chloride have been prepared by free radical solution polymerization with different crosslinkers. They were subjected to repeated cycles of swelling and de-swelling in deionized water and NaCl solution. The conductivity of the swelling medium was measured and related to the swelling/de-swelling characteristics of the SAPs. The swelling capacity was also determined in saline solution. The swelling and de-swelling processes were described by first-order kinetics. The SAPs exhibited varied swelling capacity for crosslinkers of the same functionality as well as different functionality. The SAPs were used to adsorb the dye Orange G at different initial concentrations of the dye. The equilibrium adsorption data followed the Langmuir adsorption isotherms. The SAPs were also used to adsorb three other dyes, namely, Congo red, Amido black and Alizarin cyanine green. They exhibited different adsorption capacities for different dyes. The adsorption phenomenon was found to follow first-order kinetics. [ABSTRACT FROM AUTHOR]

The results of kinetic studies of bacterial depyritization of HCl-kerogen concentrate of Aleksinac (Serbia) oil shale by the chemolithoautotrophic thionic bacteria Thiobacillus ferrooxidans under discontinuous laboratory conditions at various temperatures (0, 20, 28 and 37 ºC) at a pH of ca. 1.5 are presented in this paper. Low pH prevents the occurrence of the precipitation of iron(III)-ion hydrolysis products on the substrate particles and thereby reduces the process efficiency. Bacterial depyritization is developed as per kinetics of the first order. The activation energy which points to a successive mechanism of pyrite biooxidation, was computed from the Arrhenius plot. The biochemical kinetics indicators point to a high affinity of the bacteria toward pyrite but small values of Vmax, which are probably the result of decelerated metabolic processes due to the low pH value of the environment resp. the large difference of thepHbetween the external medium and the cell interior.

The suitability of LSV to study adsorption kinetics of metal ions was evaluated using Cu2+ adsorption on Amberlite® IR-120 as a model system. LSV provided results in agreement with conventional batch method with remarkable decreasing on analysis time and reagents consumption, since no adsorbent/adsorbate separation is required. Adsorption curves can be obtained in situ using only one portion of adsorbate solution. LSV provides higher temporal resolution for adsorption curves, which is indispensable to evaluate adsorption mechanisms and the performance of new adsorbent materials. Therefore, LSV not only saves time and reagents but also provides better quality of kinetic adsorption data. [ABSTRACT FROM AUTHOR]

Carbon dioxide post-combustion capture process using an aqueous solution of 30 wt% of monoethanolamine (MEA) is considered the most mature solution for CO 2 removal from bulk CO 2 gas streams. Although this amine based process is considered mature and has good performance characteristics such as good CO 2 absorption and high kinetics; it has high energy requirement which is approximately 3.6-4 GJ/ton of CO 2 . This high energy demand is the driving force behind the research activities seeking novel solvents with lower energy consumption. This work focuses on the thermodynamic and kinetics characterization of new amine-based solvents to evaluate their potential for CO 2 removal. A screening of different amines structure was done for the determination of the CO 2 loading by using solvent screening setup (S.S.S.) at 313.15K and a pressure of 1 bar containing 15%vol CO 2 and 85%vol N 2 . For the evaluation of the heat of absorption, a micro-reaction calorimeter was used at 313.15K and atmospheric pressure with pure CO 2 . The kinetics properties were obtained with stopped-flow equipment to measure the pseudo-first order reaction k 0 (s -1 ) at 298.15, 303.15, 308.15 and 313.15K. The results show that two tertiary amines, 2-(dimethylamino)ethanol (2DMEA) and 3-dimethylamino-1-propanol (3DMA1P), have high potential to blend with primary or secondary amine in order to improve the CO 2 loading, the heat of absorption and the reaction kinetics instead of using MDEA. [ABSTRACT FROM AUTHOR]

Kinetics of Brazilian iron ore fines reduction was investigated in a micro fluidized bed, a newly developed kinetics analyzer for gas-solid reactions, where the effects of external and internal diffusion were significantly reduced by modifying the operation conditions. The reducing gas was a mixture of CO and N 2 and the temperature ranged from 973 K to 1123 K. The experimental data was analyzed with respect to the reduction mechanism of iron oxides, and the feasibility of the segment treatment on the experimental data was discussed. The kinetics parameters were determined by the iso-reduction degree method as well as models matching method, and compared with available data in the literature. Moreover, a reduction model for iron ore fines was hence established in terms of piecewise differential rate function, and the reduction stage Fe x O→Fe is considered as the most likely limit step during the reduction of iron ore fines. [ABSTRACT FROM AUTHOR]

Cr and N-codoped TiO 2 nanotubes with larger specific surface area and smaller band gap energy compared with pure TiO 2 nanotubes were prepared via a two-step process of hydrothermal and post-impregnation method. The obtained catalysts were characterized by TEM, XRD, XPS, BET, FT-IR and UV–Vis DRS measurements for investigating nanostructure, crystal phase, specific surface area, bonding state and light-harvesting properties of these samples, respectively. Additionally, the effects of doping amount of Cr ions on the morphology, crystal structure, optical adsorption and photocatalytic activity of codoped TiO 2 nanotubes were investigated. The photocatalytic activity was evaluated by degradation of methyl orange (MO) under visible light for 100 min. It was found that the highest photocatalytic activity could be realized when the concentration of Cr was 1.06%, and the degradation rate was up to 97.16%, far higher than that of undoped TiO 2 nanotubes (10.56%). In addition, photocatalytic degradation of MO on codoped TiO 2 nanotubes surface was proven to be in accordance with the first-order kinetics. [ABSTRACT FROM AUTHOR]

In the present work, the PLLA mesophase formation and its kinetics at the advent of a chain mobility accelerator (polyethylene glycol (PEG)) are investigated by wide angle X-ray diffraction (WAXD) and time-resolved Fourier transform infrared spectroscopy (FTIR). It is interestingly found that the presence of PEG could accelerate the formation of PLLA mesophase notably due to the enhanced chain mobility, giving rise to a substantially reduced half time ( t) of PLLA mesophase formation from 129 min to 8 min. The Avrami exponents ( n) for the kinetics of mesophase formation are ∼0.5 for neat PLLA and 1 for PLLA/PEG, respectively, indicating that 1D-rod growth through heterogeneous nucleation occurs during formation of PLLA mesophase. Tensile testing demonstrates that PLLA mesophase could increase the tensile strength and modulus but decrease the elongation at break. [ABSTRACT FROM AUTHOR]

Native horse heart cytochrome c (cyt c) displays a very low reactivity toward ligands and does not exhibit catalytic properties. However, upon bovine cardiolipin (CL) binding, cyt c achieves myoglobin-like properties. Here, NO binding to CL-cyt c(III) between pH 7.2 and 9.5, at 20 °C, is reported. At pH 7.2, CL-cyt c(III) undergoes reversible nitrosylation, whereas between pH 7.9 and 9.5 CL-cyt c(III) undergoes irreversible reductive nitrosylation leading to the formation of CL-cyt c(II)-NO. Over the whole pH range explored, first-order kinetics of NO binding to CL-cyt c(III) ( k = 9.3 s−1) indicates that ligand binding is limited by the cleavage of the weak heme-Fe distal bond. Between pH 7.9 and 9.5, nitrosylated CL-cyt c(III) converts to the ligand-free ferrous derivative (CL-cyt c(II)), this process being pH-dependent ( hOH− = 3.0 × 103 M−1 s−1). Then, CL-cyt c(II) converts to nitrosylated CL-cyt c(II), in the presence of NO excess. The value of the second-order rate constant for CL-cyt c(II) nitrosylation is essentially pH-independent, the average value of lon being 1.4 × 107 M−1 s−1. These results agree with the view that CL-cyt c nitrosylation may play a role in apoptosis regulation. © 2014 IUBMB Life, 66(6):438-447, 2014 [ABSTRACT FROM AUTHOR]

Objetivo. Comparar las cinéticas y activaciones, unificar las purificaciones y determinar las secuencias de los terminales-N de los plasminógenos Ovis aries y humano. Materiales y métodos. Los plasminógenos fueron purificados por el mismo método: cromatografías de afinidad e intercambio iónico, activados con urocinasa, la secuencia de los terminales-N se realizó por el método de Edman Resultados. La afinidad de la plasmina Ovis aries por el sustrato cromogénico fue de 0.45 mM, 11.8 veces mayor que la afinidad de la plasmina humana (5.3 mM). Conclusiones. Se confirma y unifica el método de purificación de los plasminógenos del plasma, para todos los mamíferos. La alta afinidad de la plasmina Ovis aries confirma una mayor afinidad de las plasminas animales por el sustrato cromogénico, en comparación con la plasmina humana

Highlights: [•] The thermal shrinkage of porcelain stoneware bodies was predicted by a semi-theoretical model. [•] The dimensional stability range of compositions was determined by hot stage microscopy. [•] The effects of technical factors on thermal shrinkage were evaluated by dilatometry. [•] The order of sintering, m, depends on milling time. [•] The forming pressure cannot affect the sintering rate. [ABSTRACT FROM AUTHOR]

Abstract: Absorbing CO2 with amine solutions is one of the most promising methods of CCS and has been widely applied. In order to improve efficiency and reduce costs, new solvents need to be selected. In this work, two amine solvents, N,N-dimethylethanolamine(DMEA) and Triethylene diamine (TEDA), have been characterized, with the use of gas- liquid reactor for CO2 solubility and kinetic rate measurements. Solubility of CO2 has been measured for amine concentrations of 1.0, 2.5 and 4.0mol/L at temperatures of 313.2K, 343.2K, 373.2K, and 393.2K while partial pressure of CO2 varies from 1 to 300kPa. The e-NRTL model has been used for these amine-water-CO2 systems in order to calculate CO2 solubility. Meanwhile the thermo-regulated constant interfacial area Lewis-type cell was also operated to obtain absorption kinetic data for CO2 absorption in 0.5M and 1.0M amine solutions. [Copyright &y& Elsevier]

This article describes a new route for silica gel silylation and immobilization of aliphatic amines based on microwave-assisted solvent free synthesis to produce new solid phase extractors. The mode of synthesis was optimized under microwave conditions and achieved in a short time without using solvents. The produced phases named: silica gel- monoamine (SG-MA), silica gel- ethylenediamine (SG-EDA) and silica gel- diethylenetriamine (SG-DETA). The selectivity of these phases towards the uptake of Cu(II) and Fe(III) was checked using batch equilibration technique. Microwave radiation power and time of radiation were optimized to obtain the highest metal uptake values. The novel synthesized silica amine phases were characterized using Fourier transform infrared spectra and scanning electron microscope. The effects of different parameters including, hydrogen ion concentration, initial metal ion concentration, mass of the phase and shaking time on binding capacities of both Cu(II) and Fe(III) were explored. Results of sorption isotherms of the phases were better fitted with the Langmuir model (r2≥ 0.950). In addition, the kinetics data were best fitted with the pseudo–second-order type (r2= 0.999). Application of SG-MA for removal of Cu(II)- and Fe(III)-spiked natural water samples was achieved satisfactorily using batch experiments. The results were found to refer to superior recovery percentages (90.0–97.01 ± 0.010–0.521%) with no significant matrix interferences. [ABSTRACT FROM AUTHOR]

The influence of secondary structures of DNA oligonucleotides on thermodynamics and kinetics at the formation of their bimolecular complexes (duplexes) has been studied. The models considering inherent secondary structures of duplex components and their influence on quantitative thermodynamic and kinetic characteristics of the duplexes have been developed. The values of thermodynamic impacts given by individual structural elements of the double helix have been shown to depend on hairpin structuring of the duplex components. The «concentration» method to consider oligonucleotides intramolecular structure with thermodynamic parameters of bimolecular duplex formation has been proposed. According to stop-flow measurements, the observed values of association and dissociation constants are influenced by the presence of inherent structures in duplex components. The influence observed is increased with the lowering of the sample temperature. The analysis of experimental data involving the developed models provides the possibility to determine «proper» kinetic constants for the helix-to-coil transition. The difference between observed and calculated rate constants can amount up to two or more orders of magnitude. [ABSTRACT FROM AUTHOR]

Irreversible degradation of quercetin and rutin, dissolved in methanol and water, induced by continuous UV-irradiation from two different sub-ranges (UV-B and UV-C) has been studied in this work. The degradation of both flavonoids is related to formation of UV-induced degradation products: both processes follow first-order kinetics. The degradation and products formation rate constants are both dependent on the involved UV-photons energy input in both solvents. [ABSTRACT FROM AUTHOR]

Wollastomte (CaSiO3) dissolution rates were measured at 25°C in 0.01 M NaCl using a mixed-flow reactor as a function of pH (5 to 12) and concentration of forty organic ligands. Mostly stoichiometric dissolution was observed at these conditions. For seven ligands (acetate, citrate, EDTA, catechol, glutamic acid, 2,4- dihydroxybenzoic acid, glucuronic acid), batch adsorption experiments and electrokinetic measurements performed as a function of pH and ligand concentration confirmed the interaction of ligands with >CaOH2+ sites and allowed quantification of their adsorption constants. The effect of investigated ligands on wollastomte dissolution rate was modeled within the framework of the surface coordination approach taking into account the adsorption of ligands on dissolution-active sites and the molecular structure of the surface complexes they form. A positive correlation between surface adsorption constant and the stability constant of the corresponding reaction in homogeneous solution was observed. At neutral and weakly alkaline pH, the following total dissolved concentrations of ligands are necessary to double the rate of wollastomte dissolution: EDTA (10-4 M), phosphate (1.5· 10-4 M), catechol (3 · 10-4 M), 8-hydrox4yquinoline, gallic acid or adipate (5 · 10-4 M), 3,4-DHBA (7· 10-4 M), PO3- (7.5 · 10-4 M), glutamate (0.002 M), citrate (0.003 M), malate or 2,4-DHBA (0.004 M), phthalate or succinate (0.005 M), tartrate (0.006 M), thioglycolate (0.008 M), aspartame (0.01 M), gluconate, ascorbate (> 0.01 M), malonate, diglycolate or lactate at pH 8.4 (0.02 M), formate or fumarate (0.05 M), oxalate (>0.05 M), bicarbonate (0.075 M), lactate atpH 5.6 (0.1 M), acetate (> 0.1 M), salicylate (0.15 M), humic acids (> 54 mg/L of dissolved organic carbon, DOG), gum xanthan (1.5-2.0 g/L). Sorbitol, mannitol, glucose, glucosainine, saccha. rose, fulvic acids and sifica at pH ∼ 7 exhibit weakly inhibiting or no effect up to concentration of 0.1 M. The presence of the following ligands leads to a decrease of dissolution rates by a factor of 2: sifica at pH 10.7 (2 · 10-4 M), glucuronic acid (0.001 M), algae exudates (30 mg/L DOC), mannit (0.02 M), urea (>0.05 M), pectin (>15 g/L), alginic acid (> 2 g/L). Overall, results of this study demonstrate that high concentrations (0.001-0.01 M) of organic ligands, whether they are originated from organic matter, enzymatic degradation or bacterial metabolic activity, are necessary to appreciably enhance wollastonite dissolution. This is further corroborated by batch experiments on live and dead cultures of soil bacteria Pseudomonas aureofaciens interaction with wollastonite. The release rates of both Ca and Si are only weakly affected by the presence of live or dead bacterial cells in inert electrolyte solution and in nutrient media: there is only ∼20 percent-increase of dissolution rate in experiments with live cultures compared to dead cultures. However, the reproducibility of rate measurements in ligand-free solutions at 7 ⩽pH ⩽8 achieves ± 30 percent. Therefore, the effect of extracellular organic products on the weathering rate of Ca-bearing minerals is expected to be weak and the acceleration of "basic" silicate rocks dissolution in natural settings in the presence of soil bacteria is likely solely due to the pH decrease. [ABSTRACT FROM AUTHOR]

Continuous hemodiafiltration (CHDF) has been performed for the treatment of severe acute pancreatitis. Phospholipase A2 (PLA2) is one of the important mediators which exacerbate acute pancreatitis, but whether PLA2 can be removed by CHDF is unclear. In this study, the kinetics of group IB and group IIA PLA2 was examined at the first session of low-volume CHDF in eight patients with severe acute pancreatitis. CHDF was performed using polysulfone hemofilters (surface area: 0.7 m2) at a blood flow rate of 100 mL/min and a filtration and dialysate flow rate of 10 mL/min each. The plasma concentrations of group IB and IIA PLA2 before the start of CHDF were 47.4 ± 52.0 µg/L and 352 ± 390 µg/L, respectively, and did not change significantly. The clearances of group IB and IIA PLA2 achieved by the CHDF circuit 1 h after the start of CHDF were 20.7 ± 11.6 mL/min and 16.7 ± 4.4 mL/min, respectively, with both clearances decreasing significantly with time. The clearance of group IB PLA2 into the waste fluid tended to increase with time; however, the concentrations of group IIA PLA2 in the waste fluid were less than the measurable sensitivity. These results indicate that group IB PLA2 is adsorbed on the hemofilter membrane in preference to being removed into the waste fluid, while group IIA PLA2 is mainly removed by adsorption. However, low-volume CHDF is not effective at eliminating the group IB and IIA PLA2 plasma concentration. [ABSTRACT FROM AUTHOR]

Aerobic granules are microbial aggregates possessing excellent settling ability and high-porosity structure. In this study, aerobic granules as a novel type of biosorbent were used for cerium's removal from aqueous solution simulating the polluted industrial wastewater. Batch trials were conducted at different initial cerium ion and granule concentration. Biosorption kinetics was also studied. The biosorption conformed to a first-order kinetics model. The results showed that the biosorption ability of aerobic granules was related to both initial cerium ion and granule concentration. The maximum biosorption capacity of cerium by aerobic granules was 357 mg g - 1 granules. The aerobic granules were settled down by gravity from the aqueous solution in one minute after the biosorption experiments. Thus, the post-separation of the conventional suspended biosorbents from the treated effluent could be ignored in the aerobic granule-based biosorption process. All the results confirmed the technical feasibility of the biosorption process by aerobic granules. [ABSTRACT FROM AUTHOR]

The reduction of selenium(IV) in aqueous solution at pH 6.1 is described employing optical and conductometric pulse radiolysis methods. The reduction of selenium dioxide by hydrated electrons yields SeO-2 with a rate constant of 1.7 × 109 dm3 mol-1 s-1. On the 1 ms time-scale, this reduction is followed by a number of processes yielding Se2O2-4, HSe2O3-5 and H2Se4O6-10 as intermediates with the rate constants 2k2 = 2 × 109 , k3 = 1 × 109 and 2k4 = 1.6 × 108 dm3 mol-1 s-1. The extinction coefficients of the intermediates have been determined by simulating the kinetic traces at different wavelengths, and based on those values the respective absorption spectra were constructed. If the solution is irradiated by several pulses of high-energy electrons or with 60Co γ-rays, small selenium clusters are produced exhibiting a broad absorption with a maximum at 270 nm. These results suggest that the final product of the reduction of Se(IV) by hydrated electron is the selenium aggregate. The selenium clusters are stable for some months in the presence of air and are characterized using transmission electron microscope with a diameter ranging between 50 and 120 nm. [ABSTRACT FROM AUTHOR]

In the study, anaerobic digestion of residues from rose oil industry was investigated by using a laboratory scale completely mixed batch reactor in volume of 10 L and 4 small reactors in volume of 400 mL. Ten liters reactor isolated with a water jacket and 0.4 L reactors settled into a water bath were operated at 35 ± 1°C. The study supplies biochemical methane potential of hydrolyzed and original residues. Experimental results showed that hydrolyzed rose residue produced a bit more methane than original residue. Methane production results were analyzed with first-order and Chen&Hashimoto's models, and Chen&-Hashimoto's model was found to be more suitable than first-order kinetic model. [ABSTRACT FROM AUTHOR]

Absorption spectral studies on lanthanides are described, dealing with 4f–4f transitions as structural probe in chemical and biochemical reactions, and compositional dependence of intensity parameters in order to understand the structure and nature of lanthanide bimolecular interaction. This review is basically addressed to the suitable application of solution absorptional spectral spectroscopy: (i) in probing the binding characteristics and multimetal simultaneous coordination of biomolecules, (ii) following the different steps involved n complex sol-gel processes involving heterometallic alkoxides as precursors fore generation of suitable materials for future computing devices, and (iii) in pursuing the progress of some organic synthesis, specially Meerwin-Ponndorf-Verley reaction and Diels-Alder cycloaddition reaction, homogeneously catalysed by lanthanides. Solution kinetics of interactions of lanthanides involved in the reactions is presented. [ABSTRACT FROM AUTHOR]

Understanding the factors that affect the activity of Human T-cell Leukemia Virus type I (HTLV-I) protease is essential for the discovery of inhibitors to be used for the treatment of HTLV-I infection, but little has been reported on the protease to date. Here we report the production of HTLV-I protease in purified yields greater than 150 mg/L, determination of its extinction coefficient, and determination of the optimum conditions for cleavage of the p19/24 substrates (DABCYL)-(GABA)-PQVL-Nph-VMH-(EDANS), (DABSYL)-(GABA)-PQVL-Nph-VMH-(EDANS), and (DABSYL)-(GABA)-PQVLPVMH-(EDANS). The highest activity was found at pH 5.2-5.3 and 37°C. There was no effect on activity upon change in sodium chloride concentration from 0 to 1500 mM. The values of Km and kcat for cleavage of these substrates by the protease with and without the histidine tag were determined. [Copyright &y& Elsevier]

Rh(III) polypyridine complexes ([ Cp*Rh(ppy)(H2O)]2+; ppy = 2,2′-bipyridine, 2,2′-bipyridine-4,4′-dicarboxylate, o-phenanthroline, tetrahydro-4,4′-dialkyl- bis-oxazole) oxidize in organic or aqueous alkaline solution primary and secondary alcohols to aldehydes or ketones and are thereby reduced to the Rh(I) complexes Cp*Rh( ppy). The Rh(III) form can be regenerated byoxidants like pyruvate or oxygen, making the reaction quasi-catalytic. The reaction follows anautocatalytic pathway; hydrogen transfer from the α-CH2 group of an alcoholate complex [ Cp*Rh( ppy)(O R)]+ to Cp*Rh(I)( ppy) is suggested to yield the Rh(II) intermediate Cp*Rh( ppy)H as the key and rate determining step. The knowledge of Rh(III)/Rh(I) redox potentials allows to estimate the thermodynamic driving force of the reaction which is not more than about 300 mV. [ABSTRACT FROM AUTHOR]

The kinetics of the oxidation of rac-serine by permanganate in aqueous alkaline medium was studied spectrophotometrically. The reaction showed first order kinetics in permanganate ion concentration and an order less than unity in rac-serine and alkali concentration. Increasing ionic strength and decreasing dielectric constant of the medium increase the rate. The oxidation reaction proceeds via an alkali-permanganate species which forms a complex with rac-serine. The latter decomposes slowly, followed by a fast reaction between a free radical of rac-serine and another molecule of permanganate to give the products. There is a good agreement between the observed and the calculated rate constants under different experimental conditions. Investigations at different temperatures allowed the determination of the activation parameters with respect to the slow step of the proposed mechanism. [ABSTRACT FROM AUTHOR]

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A mathematical model describing microbial transport and growth in a heterogeneous aquifer domain, composed of overlapping subdomains of high-permeability and low-permeability materials, is developed. Each material is conceptually visualized as a continuum which occupies the entire considered spatial aquifer domain. Based on the assumption that advection in the low-permeability domain is negligible, the mathematical model is solved by using a publically available reactive transport code. The importance of modeling microbial transport and growth in such a dual-porosity system is demonstrated through a hypothetical case study. [ABSTRACT FROM AUTHOR]

Two species of marine diatoms. Skeletonema costatum (Grev.) Cleve and Phaeodactylum tricornutum Bohlin were grown in batch and continuous cultures on four different nitrogen compounds (nitrate, nitrite, ammonium, urea). Carbon and nitrogen uptake were measured simultaneously with the stable isotopes [sup13]C and [sup15]N. Nitrogen uptake generally increased with N concentration N sources. Carbon fixation was decreased for up to 5 h following the addition of the N compound. Nitrite generally had the greatest inhibitory effect on C uptake. Carbon-to-nitrogen uptake ratios decreased with increasing dissolved N concentration, becoming lower than one. These effects are essentially short-term and differ from long-term influences of the N source on the cellular chemical composition. [ABSTRACT FROM AUTHOR]