Excess Alkali Research Articles

Synthesis, characterization and stabilization effect of antioxidant-functionalized celluloses

Phenolic antioxidants were immobilized on cellulose nanocrystals and microcrystalline cellulose to reduce their loss. The products were synthesized with antioxidant acid chlorides forming ester bonds, and some additionally grafted with aliphatic acid chlorides to improve their solubility in non-polar polymeric matrices. The products were fully characterized using FT-IR, solid-state NMR, X-ray diffraction, and thermogravimetric analysis. The quantity of grafted groups was determined through alkaline hydrolysis and subsequent titration of the excess of alkali. The stabilization effect of the products was verified by oxidation induction time measurements in squalane. Different mixing ratios to test the influence of stabilizer amount were used. The products are compared and influences on the stabilization effect discussed.

Viscosity of pantelleritic and alkali-silicate melts: Effect of Fe redox state and Na/(Na + K) ratio

The viscosity of two series of synthetic alkali silicates, corresponding to Al-bearing pantelleritic and Al-free tri-silicate compositions, has been investigated as a function of temperature, iron redox and Na/(Na+K) ratio. Low temperature (708–1000K) viscosities were determined by the micropenetration technique in the 109.6 to 1013.6Pas range. The effect of Fe2+/Fetot, from 0.15 to 0.86, was explored for [Na/(Na+K)] ratios from 0 to 1. The results demonstrate a strong decrease of viscosity with the replacement of Na for K in both the Al-bearing and Al-free compositions. In the Al-bearing pantelleritic glasses (Ebu) the viscosity as well as the activation energy for viscous flow decrease with an increase of Fe2+/Fetot from 0.15 to 0.76. In contrast, no measurable changes in viscosity occur in the Al-free tri-silicate glasses (NFS and KFS) as Fe2+/Fetot ratio varies from 0.15 to 0.86. The comparison of the pantelleritic glasses with peralkaline compositions from the literature stresses the strong influence of iron redox on the overall viscosity of such melts. This suggests that the contribution of iron species should be accounted for in the calculation of agpaitic index (AI) if magma Fe3+ contents are known.One peculiarity of peralkaline magmas is the excess of alkali to alumina, which generally results in lower viscosities of pantelleritic liquids compared with more common metaluminous rhyolites and exerts a primary control of the rheological behaviour of these melts.Our new viscosity data, combined with existing literature, allow more accurate constraints on the nature and eruption of the pantelleritic magmas. Moreover, the present experimental study can be used to improve the viscosity models that mostly do not take in consideration parameters as iron redox in the viscosity prediction.

Modest U-Shaped Association between Dietary Acid Load and Risk of All-Cause and Cardiovascular Mortality in Adults

Background: Conflicting evidence associates diet acidity with the incidence of chronic diseases such as hypertension, diabetes, kidney disease, and bone-mineral disorders. It is currently unknown whether dietary acidity is associated with death.Objective: We investigated the association of dietary acid load with the risk of all-cause and cardiovascular disease (CVD) mortality.Methods: We used data from 2 prospective cohorts, the Swedish Mammography Cohort and the Cohort of Swedish Men, which included 36,740 women and 44,957 men aged 45–84 y at the start of a 15-y follow-up period (1998–2012). Acid load was estimated from food-frequency questionnaires by use of the validated potential renal acid load (PRAL) algorithm. Deaths were ascertained via record linkage. Associations of PRAL with mortality were modeled by use of restricted cubic splines.Results: The median PRAL was 0.65 mEq/d (range: −109 to 81.5 mEq/d) in women and 12.3 mEq/d (−111 to 121 mEq/d) in men. During a mean of 13.5 ± 3.3 y of follow-up, there were 8576 and 13,332 deaths, of which 3203 and 5427 were attributed to cardiovascular causes in woman and men, respectively. In both sexes, a nonlinear U-shaped relation was observed, with higher mortality rates for both dietary acid and alkali excess. Compared with neutral PRAL (0 mEq/d), the HRs for all-cause mortality for the 10th and 90th percentiles of PRAL were 1.05 (95% CI: 1.01, 1.10) and 1.03 (95% CI: 0.98, 1.08), respectively, in women. The corresponding results for men were HRs 1.01 (95% CI: 1.00, 1.02) and 1.04 (95% CI: 1.00, 1.08) respectively. This relation was slightly stronger for CVD mortality.Conclusions: Excess diet alkalinity and acidity both showed weak associations with higher mortality in Swedish adults. An acid-base balanced diet was associated with the lowest mortality, but the magnitude of mortality reduction was modest. The Swedish Mammography Cohort was registered at as NCT01127698. The Cohort of Swedish Men was registered at clinicaltrials.gov as NCT01127698. The Cohort of Swedish Men was registered at clinicaltrials.gov as NCT01127711.

High temperature performance of mullite whisker-reinforced ZTA

In this work, an oxide-based ceramic matrix composite (CMC) consisting of a zirconia toughened alumina (ZTA) matrix and reinforced with mullite whiskers is produced with the purpose of providing more oxidation resistance and cost-effective alternative to covalent discontinuously reinforced ceramics. ZTA has enhanced toughness, strength and creep resistance over single-phase alumina or zirconia. ZTA can further be strengthened by the inclusion of SiC whiskers; however, these whiskers are prone to oxidation at temperatures above 1000℃ leading to loss of properties. In this work, mullite whiskers are used as the reinforcement due to its stability in oxidizing atmospheres are high temperatures. Mullite whiskers are grown through the molten salt method and incorporated into the ZTA matrix using a colloidal processing route. The microstructure and room temperature properties have been reported in an earlier paper. Whisker additions have been shown to improve the flexural strength of ZTA at 1200℃ by 59.31%. There is some concern over the stability of large diameter whiskers at high temperatures, especially in environments with excessive moisture content or residual alkali contamination. Further work will be carried out to address these concerns as well as to develop a statistical analysis of the results presented.

Role of alkali in catalytic oxidation of p-cresols

The investigation of alkali acting as the key component during the liquid-phase catalytic oxidation of p-cresols to p-hydroxyl aromatic aldehydes is far from satisfied, thus a detailed exploration is presented. It was observed that the p-cresols were activated by alkali to form phenolate salt to ensure mild reaction conditions demonstrated by comparing the oxidation of p-cresol and its phenolate sodium. It was also found that excess alkali improved the selectivity of aldehyde by inhibiting the formation of dimeric side products in view of an analysis of the side products distribution. The alkaline alcoholic anion facilitates the 1,6-addition reaction between p-benzoquinone methide and solvent. Thus, more alkali was needed in solvents with high pKa values and high water content. The detection of trace acid during the oxidation of p-cresols suggested the phenoxy radical mechanism rather than the classic benzyl radical mechanism proposed for interpreting the oxidation of non-hydroxyl aromatic hydrocarbons. These conclusions contribute significantly to both the understanding of role of alkali during the reaction process and the mechanism study for the catalytic oxidation of cresols and non-hydroxyl aromatic hydrocarbons.

(K,Na)NbO3-based ceramics with excess alkali oxide for piezoelectric energy harvester

(K0.44Na0.52Li0.04)(Nb0.86Ta0.1Sb0.04)O3 (KNLNTS) ceramics were prepared by a solid-state reaction. The effect of excess (K,Na)2O alkali oxide on the densification, phase evolution, microstructure development, and piezoelectric properties was investigated. The figure of merit (FOM) (d33·g33) for piezoelectric energy harvesting applications was also compared between the samples with and without excess alkali oxide. The addition of the excess alkali oxide changed the tetragonal crystal structure to orthorhombic and decreased the sintering temperature by about 100°C. The dielectric constant of the orthorhombic phase is much lower than that of the tetragonal phase. The orthorhombic sample with excess alkali oxide sintered at 1020°C demonstrated higher FOM in spite of having a smaller piezoelectric constant (d33) than the stoichiometric sample sintered at 1100°C. This result indicates that a KNN ceramic with an orthorhombic composition near the MPB with a moderate piezoelectric constant and smaller permittivity is more advantageous for an energy harvesting application than that with a morphotropic phase boundary (MPB) or a tetragonal composition.

Synthesis and adsorption property of zeolite FAU/LTA from lithium slag with utilization of mother liquid

Co-crystalline zeolite FAU/LTA-0 was synthesized by hydrothermal method from lithium slag. To make the most of excess silicon and alkali sources in mother liquid derived from FAU/LTA-0, zeolite FAU/LTA-1b was synthesized in the same method with the use of mother liquid by adding a certain amount of aluminum source. Influences of different adding ways of aluminum source and recycling dosages of mother liquid on synthesis of zeolites FAU/LTA with mother liquid were investigated. The phase, microstructure and thermostability of FAU/LTA-0 and FAU/LTA-1b were characterized by XRD, SEM and TG-DTA. The calcium and magnesium cation exchange capacities (CECs) of the zeolites were determined. The results have shown that co-crystalline zeolite can be synthesized with the use of mother liquid by adding aluminum source after 2h of reaction. Compared with FAU/LTA-0, the crystal twinning structure of FAU/LTA-1b became weaker, the grain size was smaller, and the thermostability was better. With a lower dosage of mother liquid, the content of P-type impurity in product decreased significantly, and the content of LTA phase increased. The reuse rate of mother liquid can reach 48%. The CECs of FAU/LTA-1b-150 can reach 343mg CaCO3·g−1 and 180mg MgCO3·g−1, showing more excellent adsorption capacities than FAU/LTA-0 and commercial zeolite 4A. The full recycling use of mother liquid to synthesize zeolite FAU/LTA which can be applied for detergent not only improves resource utilization but also reduces production cost.

A comparative study of two methods to produce geopolymer composites from volcanic scoria and the role of structural water contained in the volcanic scoria on its reactivity

Volcanic scoria (ZG, ZK) and kaolin (MY38) were applied for producing geopolymer mortars using two methods such as fusion and conventional methods. Kaolin was transformed (700°C, 1°/min, 4h) into metakaolin and used to consume the excess alkali needed for the fusion and also to increase the amount of amorphous phase in volcanic scoria. In order to investigate the effect of structural water contained in volcanic scoria on their reactivity, only volcanic scoria were used to produce geopolymer pastes using conventional method. X-ray pattern of volcanic scoria ZG shows the presence of muscovite and TG curves indicate that ZG and ZK content approximately 6wt% and 0wt% of water respectively. Geopolymer pastes from ZK (ZKG) obtained only with volcanic scoria were handled easily after 7 days at ambient temperature. Whereas geopolymer pastes from ZG (ZGG) at the same curing condition were handled after 24h. The compressive strength of GZK (geopolymer mortars from ZK using conventional method), GfZK (geopolymer mortars from ZK using fusion method), GZG (geopolymer mortars from ZG using conventional method), GfZG (geopolymer mortars from ZG using fusion method), ZGG and ZKG are 25, 15, 39, 17, 33 and 10MPa respectively. It can be concluded that the conventional method is a good process to synthesize geopolymers using volcanic scoria. The structural water from muscovite (clayey mineral) influences positively the properties of volcanic scoria based-geopolymers.

Determination of Alkali-Sensing Parts of the Insulin Receptor-Related Receptor Using the Bioinformatic Approach

IRR (insulin receptor-related receptor) is a receptor tyrosine kinase belonging to the insulin receptor family, which also includes insulin receptor and IGF-IR receptor. We have previously shown that IRR is activated by extracellular fluid with pH > 7.9 and regulates excess alkali excretion in the body. We performed a bioinformatic analysis of the pH-sensitive potential of all three members of the insulin receptor family of various animal species (from frog to man) and their chimeras with swapping of different domains in the extracellular region. An analysis using the AcalPred program showed that insulin receptor family proteins are divided into two classes: one class with the optimal working pH in the acidic medium (virtually all insulin receptor and insulin-like growth factor receptor orthologs, except for the IGF-IR ortholog from Xenopus laevis) and the second class with the optimal working pH in the alkaline medium (all IRR orthologs). The program had predicted that the most noticeable effect on the pH-sensitive property of IRR would be caused by the replacement of the L1 and C domains in its extracellular region, as well as the replacement of the second and third fibronectin repeats. It had also been assumed that replacement of the L2 domain would have the least significant effect on the alkaline sensitivity of IRR. To test the in silico predictions, we obtained three constructs with swapping of the L1C domains, the third L2 domain, and all three domains L1CL2 of IRR with similar domains of the insulin-like growth factor receptor. We found that replacement of the L1C and L1CL2 domains reduces the receptor's ability to be activated with alkaline pH, thus increasing the half-maximal effective concentration by about 100%. Replacement of the L2 domain increased the half-maximal effective concentration by 40%. Thus, our results indicate the high predictive potential of the AcalPred algorithm, not only for the pH-sensitive enzymes, but also for pH-sensitive receptors.

Correlation between coprecipitation reaction course and magneto-structural properties of iron oxide nanoparticles

The effect of coprecipitation reaction course on the magneto-structural properties of iron oxide nanoparticles and, as a consequence, on their heating ability in alternating magnetic fields allowed in magnetic hyperthermia was studied. The parameters of coprecipitation reaction are chosen to ensure the repeatability of nanoparticles features: narrow size distribution, high crystallinity, and magnetic properties. It is established that the reaction should be carried out in an alkaline medium with slow addition of a solution of iron (II) and iron (III) salts to excess alkali. This provides a simultaneous homogeneous nucleation and a rapid growth of nanocrystals during the first minutes of the reaction. After that the reaction proceeds to the stage of slow growth of nanoparticles, which continues up to the complete exhaustion of the solution of salts. Nanoparticles unite in aggregates during the synthesis. The particles in aggregates are characterized by average size of 13 nm and polydispersity index 0.3, mixed phase composition including pure phase magnetite and the products of its oxidation (non-stoichiometric magnetite and maghemite nanoparticles). Material displays magnetization saturation of 56 emu g−1, non-zero hysteresis and distinct sextets on Mössbauer spectrum at room temperature. A glycerol dispersion of aggregated magnetic nanoparticles provides a temperature increase from 37 °C to 45 °C within tens of seconds under exposure to alternating magnetic field allowed for application in magnetic hyperthermia. The high heating ability is associated with interparticle magnetic interactions within aggregates leading to the enhancement of energy barrier of magnetization reversal.

Hierarchical Modeling of HLW Glass-Gel-Solution Systems for Stage 3 Glass Degradation

ABSTRACTThe necessity to a priori predict the durability of high level nuclear waste (HLW) glasses on extended time scales has led to a variety of modeling approaches based primarily on solution (leachate) concentrations. The glass composition and structure control the leachate and the gel compositions which in turn control what reaction products form: the leached layer is a hydrogel and reacts with the solution (leachate) to form secondary phases some of which cause accelerated glass dissolution which is undesirable. Glasses with molar excess alkali that is not bound to glass forming (Al,Fe,B)O4 structural groups in the glass resume accelerated leaching. The hydrogels of the glasses that resume accelerated leaching at long times contain excess alkali and the leachates contain excess strong base, [SB]ex. The [SB]ex further accelerates aluminosilicate gel aging into analcime with time. Glasses with no excess molar structural alkali do not resume accelerated leaching: the glass generates weak acids, [WA], in the leachate favoring hydrogel aging into clays. These data indicate that the gel layer transforms to secondary phases in situ in response to interactions with the chemistry of a continuously evolving leachate.

СОСТАВ ЭКСТРАКТОВ ЛУБА КОРЫ БЕРЕЗЫ

Planned experiment was done with variation of three parameters: the concentration of alcohol KOH and liquid flow module. Extraction was carried out in a microwave field.The effect of alkali consumption and the concentration of ethanol in the extract yield bast birch bark in the alcohol-alkaline treatment. It is noted that reducing the concentration of ethyl alcohol and alkali consumption increases yield of extractives (EW) increases. It is shown that the larger the alkali is used in the processing of the feedstock, the increasing its content in the solid residue formed excessive alkali content in the phloem after extraction. It has been found that the amount of free alkali in the solid phase is significantly less than in the extract. No clear relationship alkali content in the extracts from the amount of the alkali used for the experiments. Get adequate regression equations of the alkali content in the extract and a solid residue.Study the chemical composition of an alcohol-alkali bast birch bark extracts obtained after microwave extraction. A selective analysis of the obtained extracts. Standard chromatograms obtained mixture phenolic compounds and one of the extracts of the samples. Presented calibration dependence of the integral intensity of the chromatographic signal (S) the concentration c (mg / dm3) of analytes. Results of investigation of the compounds detected in the content of the extracts.

An interlaboratory comparison for the quantification of aqueous dimethylsulfide

An interlaboratory comparison (ILC) was conducted to evaluate the proficiency of multiple laboratories to quantify dimethylsulfide (DMS) in aqueous solution. Ten participating laboratories were each supplied with blind duplicate test solutions containing dimethylsulfoniopropionate hydrochloride (DMSP HCl) dissolved in acidified artificial seawater. The test solutions were prepared by the coordinating laboratory from a DMSP HCl reference material that was synthesized and purity certified for this purpose. A concentration range was specified for the test solutions and the participating laboratories were requested to dilute them as required for their analytical procedure, together with the addition of excess alkali under gas‐tight conditions to convert the DMSP to DMS. Twenty‐two DMS concentrations and their estimated expanded measurement uncertainties (95% confidence level) were received from the laboratories. With two exceptions, the within‐laboratory variability was 5% or less and the between‐laboratory variability was ~ 25%. The magnitude of expanded measurement uncertainties reported from all participants ranged from 1% to 33% relative to the result. The information gained from this pilot ILC indicated the need for further test sample distribution studies of this type so that participating laboratories can identify systematic errors in their analysis procedures and realistically evaluate their measurement uncertainty. The outcome of ILC studies provides insights into the comparability of data in the global surface seawater DMS database.

Interfacial water in the vicinity of a positively charged interface studied by steady-state and time-resolved heterodyne-detected vibrational sum frequency generation.

To investigate the properties of water in the close vicinity of a positively charged surfactant/water interface, steady-state and femtosecond time-resolved interfacial vibrational spectra were measured in the presence of excess alkali halide salts. The steady-state Imχ((2)) spectra show a drastic intensity decrease with excess salts, indicating that the thickness of the probed water layer is substantially reduced. Fluoride salts do not noticeably affect spectral features in the OH stretch region whereas the chloride and bromide salts induce significant blue shifts of the OH stretch frequency. Femtosecond time-resolved ΔImχ((2)) spectra obtained with fluoride salts exhibit a very broad bleach even at 0 fs as observed without excess salts, while chloride and bromide salts give rise to a narrow spectral hole burning. These results indicate that the excess chloride and bromide ions strongly interact with interfacial water in the vicinity of the charged interface and it suppresses intramolecular coupling (i.e., Fermi resonance) that causes spectral broadening.

Interaction between Co2P4O12 and alkali metal nitrate (chloride) melts

Reactions between Co2P4O12 and alkali metal nitrate (chloride) melts was studied in the temperature range 350–400°C (800–850°C) at different phosphate/melt ratios. The effect of the nature of an alkali metal and the ratio between the components in the Co2P4O12-MINO3 (MICl) system on composition of the reaction products was established. The resulting crystalline phases (NaCoPO4, Na4Co3(PO4)2P2O7, Na9Co3(PO4)5 and KCoPO4) were studied by X-ray powder diffraction, IR and electron spectroscopy, and scanning electron microscopy. The features of transformation of the Co2P4O12 framework into KCoPO4 under the effect of excessive alkali metal ions in the melt are discussed.

Raman analysis of perrhenate and pertechnetate in alkali salts and borosilicate glasses

Sodium borosilicate glasses containing rhenium or technetium were fabricated and their vibrational spectra studied using confocal Raman microscopy. Glass spectra were interpreted relative to new high‐resolution spectra of pure crystalline NaReO4, KReO4, NaTcO4, and KTcO4 salts. Spectra of perrhenate and pertechnetate glasses exhibited sharp Raman bands, characteristic of crystalline salt species, superimposed on spectral features of the borosilicate matrix. At low concentrations of added KReO4 or KTcO4, the characteristic pertechnetate and perrhenate features are weak, whereas at high additions, sharp peaks from crystal field‐splitting and C4h symmetry dominate glass spectra, clearly indicating ReO4− or TcO4− is locally coordinated with K and/or Na. Peaks indicative of both K and Na salts are evident in many Raman spectra, with the Na form being favored at high concentrations of the source chemicals, where more K+ is available for ion exchange with Na+ from the base glass. The observed ion exchange likely occurred within depolymerized channels where nonbridging oxygens create segregation from the glass network in regions containing anions such as ReO4− and TcO4− as well as excess alkali cations. Although this anion exchange provides evidence of chemical mixing in the glass, it does not prove the added salts were homogeneously incorporated in the glass. The susceptibility to ion exchange from the base glass indicates that long‐term immobilization of Tc in borosilicate glass must account for excess charge compensating alkali cations in melt glass formulations. Published 2014. This article is a U. S. Government work and is in the public domain in the USA.

Extreme metabolic alkalosis: Excessive alkali intake due to ulcerative disease

Extreme metabolic alkalosis: Excessive alkali intake due to ulcerative disease

The effect of pre-treatment on the thermal performance of fly ash geopolymers

This paper presents a study on the thermal behaviour of fly ash geopolymers that have been pre-treated prior to thermal exposure. Thermal and mechanical analysis was conducted on geopolymers that were leached in water and gradually dried and the results were compared to untreated samples. The aim of the pre-treatment was to remove the water and the excess alkali without damaging the structure prior to high temperature exposure. Fast dehydrating water is known to damage geopolymers by inducing cracks. Alkalis are known to be network modifiers and as such, where in excess, reduce the melting point of aluminosilicate glasses. It was found that the pre-treatment produced samples with negligible thermal expansion up to 700°C and less damage associated with dehydration which increased their post firing compressive strength. The pre-treated geopolymer panel had a marginally shorter fire rating than the as-cured sample though it exhibited greater resistance to cracking and slower post dehydration temperature increases.

Simultaneous Production of Biodiesel and Free Lutein from Chlorella vulgaris

AbstractBiodiesel and valuable free lutein were demonstrated to be simultaneously produced from Chlorella vulgaris lipid extracts. The alkali catalyst used in the transesterification of triglycerides acted as a reactant in converting lutein fatty acid esters to free lutein. A maximum biodiesel yield of 33.6 % by weight of the algal lipids was obtained after a 4‐h reaction with MeOH at the MeOH/biomass ratio of 16:1 using 6 % alkali catalyst. The excess of alkali and MeOH employed in the production of biodiesel ensured the complete saponification of all lutein fatty acid esters to free lutein, giving a maximum yield of 2.3 % by weight of the algal lipids. In addition, a process for the separation of the biodiesel and free lutein products from the reaction mixture is proposed. Finally, a preliminary economic assessment was conducted, the results of which suggest that the process for the simultaneous production of biodiesel and lutein from C. vulgaris may be economically feasible.

Modification of hydrophilic cellulose fibers by monolayer growth of polystyrene chains using ATRP

The chemical modification of biopolymer-based materials by grafting synthetic polymers has received considerable attention in recent years, inasmuch as there are wide varieties of monomers available. Nowadays, the most abundant biomacromolecule, cellulose, has attracted considerable attention due to its biodegradable, biocompatible, and renewable characteristics. In this study, the surface of hydrophilic cellulose microfibers was successfully modified by polymerization of hydrophobic polystyrene using atom transfer radical polymerization (ATRP) technique in dispersion medium. In this medium, only the outer surface of the macroinitiator is available for the polymerization, so the grown polymer chains are formed as monolayer on the surface of the macroinitiator. This type of modification not only increases the mechanical properties of the cellulose backbone, but also turns the hydrophilic characteristics of cellulose into hydrophobic state. For this purpose, in the first part of this research, chloroacetylated cellulose was synthesized as macroinitiator. In the second part, the acyl content of the macroinitiator and the degree of substitution, which show the efficiency of the esterification reaction, have been determined by basic hydrolysis of the macroinitiator with KOH and back-titration of the excess alkali with HCl. Finally, the chloroacetylated cellulose was modified by graft copolymerization of styrene using ATRP method. The polystyrene chain growth is confirmed by the atomic force microscopy images.