Aqueous Sodium Carbonate Solution Research Articles

Synthesis, enzyme inhibitory kinetics mechanism and computational study of N-(4-methoxyphenethyl)-N-(substituted)-4-methylbenzenesulfonamides as novel therapeutic agents for Alzheimer's disease.

The present study comprises the synthesis of a new series of sulfonamides derived from 4-methoxyphenethylamine (1). The synthesis was initiated by the reaction of 1 with 4-methylbenzenesulfonyl chloride (2) in aqueous sodium carbonate solution at pH 9 to yield N-(4-methoxyphenethyl)-4-methylbenzensulfonamide (3).This parent molecule 3 was subsequently treated with various alkyl/aralkyl halides, (4a–j), using N,N-dimethylformamide (DMF) as solvent and LiH as activator to produce a series of new N-(4-methoxyphenethyl)-N-(substituted)-4-methylbenzenesulfonamides (5a–j). The structural characterization of these derivatives was carried out by spectroscopic techniques like IR, 1H-NMR, and 13C-NMR. The elemental analysis data was also coherent with spectral data of these molecules. The inhibitory effects on acetylcholinesterase and DPPH were evaluated and it was observed that N-(4-Methoxyphenethyl)-4-methyl-N-(2-propyl)benzensulfonamide (5c) showed acetylcholinesterase inhibitory activity 0.075 ± 0.001 (IC50 0.075 ± 0.001 µM) comparable to Neostigmine methylsulfate (IC50 2.038 ± 0.039 µM).The docking studies of synthesized ligands 5a–j were also carried out against acetylcholinesterase (PDBID 4PQE) to compare the binding affinities with IC50 values. The kinetic mechanism analyzed by Lineweaver-Burk plots demonstrated that compound (5c) inhibits the acetylcholinesterase competitively to form an enzyme inhibitor complex. The inhibition constants Ki calculated from Dixon plots for compound (5c) is 2.5 µM. It was also found from kinetic analysis that derivative 5c irreversible enzyme inhibitor complex. It is proposed on the basis of our investigation that title compound 5c may serve as lead structure for the design of more potent acetylcholinesterase inhibitors.

Evaluation of dry heat treatment of soft wheat flour for the production of high ratio cakes

An accurate method to heat treat flour samples has been used to quantify the effects of heat treatment on flour functionality. A variety of analytical methods has been used such as oscillatory rheology, rheomixer, solvent retention capacity tests, and Rapid Visco Analysis (RVA) in water and in aqueous solutions of sucrose, lactic acid, and sodium carbonate. This work supports the hypothesis that heat treatment facilitates the swelling of starch granules at elevated temperature. Results furthermore indicated improved swelling ability and increased interactions of flour polymers (in particular arabinoxylans) of heat treated flour at ambient conditions. The significant denaturation of the proteins was indicated by a lack of gluten network formation after severe heat treatments as shown by rheomixer traces. Results of these analyses were used to develop a possible cake flour specification. A method was developed using response surfaces of heat treated flour samples in the RVA using i) water and ii) 50% sucrose solution. This can uniquely characterise the heat treatment a flour sample has received and to establish a cake flour specification. This approach might be useful for the characterisation of processed samples, rather than by baking cakes. Hence, it may no longer be needed to bake a cake after flour heat treatment to assess the suitability of the flour for high ratio cake production, but 2 types of RVA tests suffice.

The effect of microwave on the crystallization process of magnesium carbonate from aqueous solutions

The effect of microwave on reactive crystallization is investigated with magnesium carbonate as the working substance. In the experiments, magnesium carbonate is precipitated by mixing aqueous magnesium sulfate and sodium carbonate solutions in a MSMPR crystallizer located in a microwave reactor. A population balance model along with crystallization kinetics is formulated to assess the influence of microwave energy input on nucleation, growth, agglomeration and breakage during crystallization process. A general high order moment method of classes (HMMC) framework is applied to solve the model numerically. The results show that crystallization kinetics parameters, including the nucleation rate constant (kn), the growth rate constant (kg), the exponent of growth rate (g) and the collision efficiency (Ψag) change significantly due to mass transfer enhancement in microwave field. Meanwhile, the exponent of nucleation (n) and the breakage rate constant (kbr) remain constant or only change slightly. It is further discovered that the crystal suspension attenuates the microwave effect during crystallization process.

Isolation of ellagic acid from pomegranate peel extract by hydrophobic interaction chromatography using graphene oxide grafted cotton fiber adsorbent

Ellagic acid, a natural polyphenol, was isolated from pomegranate peel extract by hydrophobic interaction using graphene oxide grafted cotton fiber as a stationary adsorbent. The grafted graphene oxide moieties served as hydrophobic interaction-binding sites for ellagic acid adsorption. The graphene oxide grafted cotton fiber was made into a membrane-like sheet in order to complete ellagic acid purification by using a binding-elution mode. The effects of operational parameters, such as the composition of the binding buffer/elution buffer, buffer pH, and buffer concentration, on the isolation process were investigated. It was found that 5mmol/L sodium carbonate aqueous solution is a proper-binding buffer, and sodium hydroxide aqueous solution ranging from 0.04 to 0.06mol/L is a suitable elution solution for ellagic acid purification. Under the optimized condition, the purity of ellagic acid increased significantly from 7.5% in the crude extract to 75.0-80.0%. The pH value was found to be a key parameter that determines the adsorption and desorption of ellagic acid. No organic solvent is involved in the entire purification process. Thus, a simple and environmentally friendly method is established for ellagic acid purification using a graphene oxide-modified biodegradable and bio-sourced fibrous adsorbent.

Molecular-Orbital-Based Verification of Water Photo-Splitting on Pt-Loaded TiO2: Effective Formation of HOOH and Reduced Platinum Cluster as Precursors of O2 and H2

Sayama and Arakawa reported in 1997 that Pt-loaded nc-TiO2 catalyzes effective H2O photo-splitting occurring in aqueous sodium carbonate solutions (pH8~11.5). Sayama and Arakawa’s H2O photo-splitting is now verified by density-functional theory-based molecular modeling (DFT/MM), where Yamashita-Jono’s nc-TiO2 model of [HOTi9O18H], hydrated hydroxide anion model of [HO-&H2O] and platinum triangular pillar model of [Pt6] are employed. At first, hydroxyl anion of HO-&H2O is verified to undergo endothermic one-electron transfer oxidation, giving hydrogen peroxide of HOOH&(H2O)2 via formation of hydroxyl radical of HO.&H2O and its coupling. As for verification of electron-transfer reduction of Pt6 cluster for the H2O photo-splitting to H2, the van der Waals complex of [Pt6] with nonpolar H2O trimer model of [ts-(H2O)3] is molecular-modeled, and highly exothermic electron transfer reactions verify the effective H2 formation via formation of hydrogen radical on [Pt6]. As the model of Pt-loaded nc-TiO2 catalyst, van der Waals and Coulomb interaction-based complex of [HOTi9O18H] with [Pt6] and [HO-&H2O] is successfully molecular-modeled, and the molecular orbital energy structure rationalizes that the effective water-splitting catalysis should occur via effective electron transfer from HOMO of [HO-&H2O] to LUMO of [Pt6] when the catalyst is photo-energized. DFT/MM also verifies successive oxidation of HOOH to 3O2 and photo-regeneration of HOOH via radical anion of O2 .- that could be produced from 3O2 under UV irradiance of Sayama and Arakawa’s photocatalysis systems.

Effects of prewash on the pyrolysis kinetics of cut tobacco

ABSTRACTSmoking is a big public health issue because of the harmful substances generated. To diminish the risk of smoking, cut tobacco was washed with pure water, aqueous solution of sodium carbonate, or citric acid to remove the precursors of harmful substances in this work. The composition and pyrolysis kinetics of washed cut tobacco were determined to interpret the reduction in harmful substances generated during fast pyrolysis process. Sugar and alkaloid in cut tobacco were removed partly during prewash process. Thermogravimetric analysis demonstrated that cut tobacco washed with aqueous solution of citric acid was pyrolyzed at higher temperature, while the one washed with the solution of sodium carbonate was pyrolyzed at lower temperature. The changes in composition and pyrolysis kinetics resulted in significant reduction in benzo[a]pyrene, phenol, and nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone generated during pyrolysis, demonstrating that wash of cut tobacco with suitable chemicals is a promising approach to reduce the harmful substances generated during smoking.

(n‐Bu2Sn)2O(CO3): An active, robust and recyclable organotin(IV) for the direct synthesis of linear organic carbonates from carbon dioxide and alcohols

Organotin(IV) compounds are known to promote the direct synthesis of organic carbonates from carbon dioxide and alcohols. In the past, structural studies have highlighted that the carbonato moiety is a recurring ligand of tin species collected during CO2 pressurized reactions. In a mimetic approach and in order to achieve an available and recyclable precursor, the title compound (n‐Bu2Sn)2O(CO3) (1) was prepared in a single step by reacting commercial di‐n‐butyltin dichloride with an aqueous solution of sodium carbonate. Compound 1 was characterized using infrared spectroscopy and thermogravimetric and elemental analyses. Multinuclear NMR investigations in solution were also conducted. Compound 1 was then evaluated for the direct carbonation of alcohols (methanol, ethanol, n‐butanol and isopropanol) under CO2 pressure. Recycling experiments were performed showing the efficient reuse of 1 without loss of activity. Furthermore, the infrared fingerprint of 1 was preserved even after several runs demonstrating a good stability. The effects of pressure and of reaction time on dimethyl carbonate formation were also studied.

New simple procedure to produce white lead for special use in the plastic arts and in restoration

Abstract Paints based on the pigment white lead have traditionally been used in art. Currently, however, this pigment is difficult to find, either in powder or in paint, with sufficient purity and without undesired additives. Furthermore, the traditional methods of producing it are not feasible to use in the studio or laboratory. Therefore, the present work proposes a new method of producing the pigment on a small scale, to be used in the fields of the plastic arts, in restoration of works of art, and in research. The method consists of precipitating white lead from aqueous solutions of lead nitrate and sodium carbonate. The procedure is simple, quick, and without unpleasant materials or handling, and the resulting pigment is of great purity and similar to traditional white lead.

Effects of alkyl polyglycoside (APG) on Bombyx mori silk degumming and the mechanical properties of silk fibroin fibre

Alkyl polyglycoside (APG), a nonionic surfactant, is often considered to be a green surfactant and is synthesized using glucose and long chain fatty alcohols. It is used as a degumming agent of Bombyx mori silk fibre in this study for the first time. We studied APG systematically in comparison to the traditional degumming methods, such as aqueous solutions of sodium carbonate (Na2CO3) and neutral soap (NS). After repeatedly boiling silk fibres in an aqueous solution of 0.25% APG three times for 30min and using a bath ratio of 1:90–120 (g/mL), sericin was completely removed from the fibre. SDS-PAGE showed that the degumming in APG did not induce an evident breakage of the silk fibroin peptide chains, including the light chain and P25 protein. The tensile properties, thermal analysis, and scanning electron microscopic (SEM) observation of the degummed fibroin fibre all show that APG is a degumming agent similar to NS and far superior to Na2CO3. These results indicate that APG is an environment-friendly silk degumming/refining agent in the silk textile industry and in the manufacture of silk floss quilts.

Electrically Conductive Photopatternable Silver Paste for High-Frequency Ring Resonator and Band-Pass Filter

In conventional thick-film technology, there are often problems associated with poor edges, rough surfaces, and reproducibility due to process limitations, especially for high-frequency applications. These difficulties can be circumvented by using thin-film technology, but process cost and complexity remain major concerns. In this context, photopatternable thick-film technology can offer a viable alternative due to its Newtonian rheology, which can facilitate formation of the required sharp edges. We present herein a unique attempt to formulate a photopatternable silver paste with organic (photosensitive polymer) to inorganic (silver and glass) ratio of 30:70, developed in-house by us for fabrication of thick-film-based ring resonator and band-pass filter components. The ring resonator and band-pass component structures were realized by exposing screen-printed film to ultraviolet light at wavelength of 315 nm to 400 nm for 30 s to crosslink the photosensitive polymer. The pattern was subsequently developed using 1% sodium carbonate aqueous solution. For comparison, conventional silver and silver-palladium thick films were produced using in-house formulations. The surface topology and microstructural features were examined by stereomicroscopy and scanning electron microscopy. The smoothness and edge definition of the film were assessed by profilometry. The resistivity of the samples was observed and remained in the range from 3.4 μΩ cm to 3.6 μΩ cm. The electrical properties were compared by measuring the insertion loss characteristics. The results revealed that the ring resonator fabricated using the photopatternable silver paste exhibited better high-frequency properties compared with components based on conventional silver or silver-palladium paste, especially in terms of the resonant frequency of 10.1 GHz (versus 10 GHz designed) with bandwidth of 80 MHz. Additionally, the band-pass filter fabricated using the photopatternable silver paste displayed better center frequency (f0 = 10.588 GHz) and comparable ripple and attenuation bandwidth performance on par with Cu thin film.

Full-color photonic hydrogels for pH and ionic strength sensing

We demonstrate a facile yet efficient strategy to fabricate responsive photonic hydrogels by incorporating magnetic (Fe3O4) nanoparticles into the hydrogel materials. In this approach, poly(acrylamide)-poly(2-hydroxyethyl methacrylate) (PAM-PHEMA) photonic hydrogels incorporated with linearly ordered Fe3O4 nanocrystal arrays were successfully synthesized via one-step polymerization process under an external magnetic field. The resulting hydrogel materials can be endowed with pH and ion sensing functionalities by hydrolyzing PHEMA into PAA units in sodium carbonate aqueous solutions. The whole fabrication process of the photonic hydrogels would take only ∼2.5h, including dispersing Fe3O4 NPs in monomer solution for ∼10min, photo-polymerization for ∼20min, hydrolyzation of PHEMA for ∼2h. Importantly, photonic hydrogels containing fixed number of carboxyl groups can be fabricated by controlling the content of PHEMA. The photonic hydrogels demonstrate better reproducibility and keep the same pH and ionic strength sensing abilities, which is beneficial for batch preparation.

Performance of a Pilot-Scale Entrained-Flow Black Liquor Gasifier

Pilot-scale entrained flow gasification experiments were carried out at the 3 MWth LTU Green Fuels black liquor gasification (BLG) plant, using ∼140 tons of Kraft black liquor (BL) with a dry solids content of ∼72.5%. Comprehensive mass and energy balances were performed to quantify process performance under varying pressure, load, and oxygen/fuel ratio. Carbon conversion efficiency of the BLG process was 98.3%–99.2% and did not vary systematically in response to process changes. The unconverted carbon is almost exclusively present as dissolved organic carbon in the green liquor (GL) stream. GL is an aqueous solution of sodium carbonate and sodium sulfide used to recover the inorganic pulping chemicals present in BL for reuse in the pulp mill. A small fraction of syngas CO is converted to formate ions dissolved in GL through reaction with hydroxide ions. Unconverted carbon present in GL solids is insignificant. Syngas produced is subsequently upgraded to methanol and dimethyl ether (DME) in an integrated ...

Utilization of cellulose nitrate waste

A two-step procedure for utilization of cellulose nitrate waste accumulated at industrial enterprises of the Russian Federation was suggested and experimentally checked. The procedure involves hydrolysis of cellulose nitrate in alkaline medium and incineration of hydrolysis products. The best reagents for complete hydrolysis of cellulose nitrate are aqueous solutions of sodium hydroxide and sodium carbonate. As demonstrated by thermal analysis and thermodynamic calculations, incineration of cellulose nitrate base hydrolysis products can be performed without using hydrocarbon fuel.

Morphology-Controlled CaCO3 Nanostructures by Modified Co-Precipitation in Pulsed Mode

Calcium carbonate nanoparticles and nanorods were synthesized by precipitation from saturated sodium carbonate and calcium nitrate aqueous solutions through co precipitation method. A new rout of synthesis was done by both using pulsed mixing method and controlling the addition of calcium nitrate. The effect of the agitation speed, and the temperature on particle size and morphology were investigated. Particles were characterized using X-ray Microanalysis, X-ray analysis (XRD) and scanning electron microscopy (SEM). The results indicated that increasing the mixer rotation speed from 3425 to 15900 (rpm) decreases the average particle size to 64±7 nm. A rapid nucleation then aggregation induced by excessive shear force phenomena could explain this observation. Moreover, by increasing the reaction temperature, the products were converted from nanoparticle to nanorods. The maximum attainable aspect ratio was 6.23 at temperature of 75°C and rotation speed of 3425. Generally, temperature raise promoted a significant homoepitaxial growth in one direction toward the formation of calcite nanorods. Overall, this study can open new avenues to control the morphology of the calcium carbonate nanostructures.

Influence of the operating conditions on the morphology of CaCO3 nanoparticles prepared by modified co-precipitation with pulse mode feeding

Calcium carbonate nanoparticles and nanorods were synthesized by precipitation from saturated sodium carbonate and calcium nitrate aqueous solutions through co precipitation method. A new route of synthesis was done by using pulse mode feeding of calcium nitrate. The effect of the agitation speed, and the temperature on particle size and morphology were investigated. The formed particles were characterized using X-ray microanalysis, X-ray analysis (XRD) and scanning electron microscopy (SEM). The results indicated that increasing the mixer rotation speed from 3425 to 15,900rpm facilitates decreasing the average particle size to 64±7nm. A rapid nucleation followed by aggregation induced by excessive shear forces phenomena could explain this observation. Moreover, by increasing the reaction temperature, the products were converted from nanoparticles to nanorods. The maximum attainable aspect ratio was 6.23 at temperature of 75°C and rotation speed of 3425. Generally, temperature raise promoted a significant homoepitaxial growth in one direction toward the formation of calcite nanorods. Overall, this study opens a new avenue to control the morphology of the calcium carbonate nanostructures.

Processing and characterization of powdered silk micro- and nanofibers by ultrasonication.

Silk derived from Bombyx mori silkworm cocoons was degummed in an aqueous sodium carbonate solution, and the resulting silk fibroin fibers were placed in an acidic aqueous solution and were treated with ultrasonication to obtain powdered micro- and nanofibers. The morphologies and spectral characteristics of these powdered silk fibers were investigated in detail. The shape, surface and structural features of the powdered fibers were affected by the ultrasonic power and media. Increasing the acidity of the ultrasonic solution and increasing the ultrasonic power increased the fiber breakage speed, resulting in shorter fiber lengths. Powdered microfibers could not be obtained in a formic acid solution, while powdered nanofibers whose diameter below 1μm were obtained in a combined formic acid and hydrochloric acid ultrasonication solution. Observation via SEM and optical microscopy revealed that the microfiber diameters were approximately 5-10μm, and those of the nanofibers were approximately 30-120nm. The analysis of laser sizer showed that the microfiber sizes ranged mainly from 20 to 100μm. FT-IR and XRD spectra demonstrated that the relative amount of β-sheets increased after the ultrasonic treatment. The ε-amino group content on the surface of the micro- and nanofibers increased significantly. These studies provide reliable methods for the preparation of nano-scale silk fibroin fibers by ultrasonication and open new avenues for the development of powdered silk fibers as advanced functional biomaterials.

New magnesium cobalt iron double hydroxides with hydrotalcite structure: Synthesis and characterization

Series ol layered double hydroxides (LDHs) of the hydrotalcite family simultaneously containing iron and cobalt cations in the positions of triply charged metal ions of the brucite-like sheets, were prepared by coprecipitation of the components from solution in an oxidative medium. The materials prepared have been characterized by X-ray powder diffraction, temperature-programmed reduction (TPR), and temperature-programmed destruction (TPD); their behavior during dehydration-rehydration cycling was studied. The layered double hydroxides were shown to be reducible when heated in flowing hydrogen. Heating to 600°C induced the reduction of cobalt and iron to doubly charged cations, and at temperatures higher than 600°C the reduction yielded the metals. The thermal destruction products of the LDHs prepared are capable of recovering their layered structure when reacted with aqueous sodium carbonate solutions; however, this capability is reduced as the cobalt content in the sample increases.

Thermal decomposition of products of desulfation of active mass of lead-acid batteries

The process of thermal decomposition of the active mass of lead-acid batteries after desulfation (desulfurization) of aqueous solution of sodium carbonate, potassium or ammonia was experimentally studied.

Thermal Degradation and Stability of Accelerated-curing Phenol-formaldehyde Resin

In order to study the thermal stability of accelerated-curing PF resin, the curing behavior of fresh PF resin was investigated in the presence of single accelerator of methylolurea derivatives (MMU), magnesium hydrate (Mg(OH)2), 25% aqueous solution of sodium carbonate (Na2CO3), and propylene carbonate (PC). Also their optimum combination was added in fresh PF resin. The thermal stability of cured phenol-formaldehyde (PF) resins was studied using thermogravimetric analysis TG/DTA in air with heating rates of 5, 10, 15, and 20 °C min-1. Thermal degradation kinetics were investigated using the Kissinger and Flynn-Wall-Ozawa methods. The results show that these accelerators can promote fresh PF resin fast curing, and the degradation of accelerated-curing cured PF resin can be divided into three stages. Single accelerator MMU, Mg(OH)2, and Na2CO3 can promote fresh PF curing at low temperatures in the first stage, while the structure of PF resin which was added with MMU and PC was more rigid, according to thermal degradation kinetics. A novel fast curing agent which is compound with MMU+Na2CO3 for PF resin is proposed; not only can it maintain the advantage of fast curing of the single accelerator Na2CO3, but it also improves the thermal stability of PF resin.

Sol-gel formation and properties of nanocrystals of solid solutions Y1 − x Ca x FeO3

Nanopowders of ferrites Y1 − xCaxFeO3 (x = 0.1, 0.2, and 0.3) were prepared by chemical coprecipitation of cations Y3+, Ca2+, and Fe3+ by an aqueous sodium carbonate solution. It was found that an increase in the calcium content leads to a decrease in the size of nanocrystals, the average size of which is 25–50 nm. Doping of yttrium orthoferrite with the doubly charged calcium ion enhances magnetization and decreases coercivity in samples.