Normal Titration Research Articles

Effect of precipitation variables on the performance of CeO2-based catalysts for waste-to-hydrogen

Waste-to-hydrogen technology, a future net-zero energy mix as a clean hydrogen source, is currently a research hotspot. To upcycle waste to high-value chemicals such as hydrogen, it is necessary to study customized catalysts for water-gas shift (WGS) reactions considering waste-derived synthesis gas. Herein, we aimed to enhance the physicochemical properties of CeO2 supported Pt catalysts by controlling the precipitation variables to develop a highly sulfur-tolerant WGS catalyst using waste-derived synthesis gas. The CeO2 support was prepared by the classic precipitation method. During precipitation, the precipitating agent was injected at different methods and rates. In the case of the normal titration method, the KOH solution was injected into the Ce precursor dissolved solution at rates of 5, 20, and 50 mL/min. In the case of the reverse titration method, the Ce precursor dissolved solution was injected into the KOH solution at rates of 5, 20, and 50 mL/min. The as-prepared Pt/CeO2 catalysts were applied to the WGS reaction with 500 ppm H2S. This work demonstrated that the titration method and titration rate affected the oxygen vacancy concentration and the active metal dispersion of the catalysts, respectively. And these properties worked in combination to determine the sulfur resistance of the catalysts. Subsequently, the high sulfur tolerance and catalytic performance of Pt/CeO2 catalyst prepared by normal titration method with the titration rate of 50 mL/min were due to the high Pt dispersion and concentration of oxygen vacancies.

THE ADOPTION OF AUTOMATED FiO2 CONTROL INTO POLISH NICUS: 2012-2019

The introduction and adoption of new technology in medicine is a continuous ever present process but it is often not studied. Insights gained from documenting such experiences can not only guide local practices but also provide valuable quality benchmarks. Automated control of FiO2 based on continuous SpO2 (A-FiO2) not only reduces the challenging task of manual oxygen titration, but also has the potential to greatly improve the morbidity and mortality of extremely preterm infants. First approved for use in Europe in 2012, it is now available on most infant ventilators outside the USA. Poland was the first region in Europe to implement its clinical use. We report experience from 619 infants from 12 centers recorded in a web-based registry established in 2013 to document its use. We found the A‑FiO2 was primarily used in the first week of life in intubated infants. However it is also successfully applied in both noninvasively supported infants and in those who were difficult to wean from oxygen and who exhibited frequent desaturations. We also found the SpO2 target range and alarm setting are not different from normal manual titration, although wider settings are also used and promise some benefit. Finally we report our plan to gather data from a national data base and detailed surveys. The surveys will document subjective aspects of this experience from a core group of centers. Details of the surveys are included and cover: experience with training and acceptance, changes in practice associated with the years of experience and barriers to broader use.

Seroepidemiology Study of Helicobacter pylori Infection and Its Effect on Cardiovascular Diseases in Karaj, Iran.

Helicobacter pylori infection occurs throughout the world between countries and races. A seroprevalence study of H. pylori infection in the occurrence of atherosclerosis (ASc) has been considered to be the main cause of cardiovascular diseases (CVDs) in part of Iran. From 600 volunteers, 97 serum samples were selected and tested for the presence of H. pylori infection. Positive and negative H. pylori infection samples were then selected for Chlamydia pneumonia and cytomegalovirus infection. Their serum levels for high-sensitive C-reactive protein (hs-CRP) and IL-6 titer were measured using an ELISA test. Prevalence of H. pylori infection was ∼68.04% in Karaj. Among the 22 samples of cytokine titration, 4 individuals were HP- and 18 were HP+. It was also noticed that 17 samples had normal titration (77.27%) of IL-6 and 3 had a high level of IL-6 (13.63%), 20 people had high hs-CRP titration (90.90%), and 2 were low level hs-CRP (9.1%). Obtained results showed that there is no significant difference between HP+ and HP- infection and IL-6 and hs-CRP titration. Results showed that H. pylori could not lead to ASc by increasing the levels of proinflammatory cytokines such as IL-6 and hs-CRP. Further studies are necessary for the detection of mechanism of H. pylori on ASc.

2C1536 等温滴定熱量測定法による複数結合部位の順・逆滴定のための汎用解析法(蛋白質_機能1,第49回日本生物物理学会年会)

2C1536 等温滴定熱量測定法による複数結合部位の順・逆滴定のための汎用解析法(蛋白質_機能1,第49回日本生物物理学会年会)

Formation and calcination temperature-dependent sintering activity of YAG precursor synthesized via reverse titration method

The composition homogeneity of YAG precursors synthesized via both normal and reverse titration co-precipitation methods is discussed. It was demonstrated that that the reverse titration process possesses better co-precipitation characteristics than the normal titration process, based on a real-time monitoring of the reaction pH and measurement of the Y/Al ratio in the precipitate. The formation process of the precipitate obtained by reverse titration method was discussed. The effect of calcination temperature on sintering properties of the YAG powder was investigated by analysis of the crystalline phase, the specific surface area, and the morphology of the powder. The shrinkage rate test of compacts made from different powders indicates that a higher calcination temperature results in a lower densification speed and shrinkage ratios. Microstructure observation shows that the ceramics made from YAG nanopowder, which was obtained at a higher calcination temperature, have a more uniform grain-size distribution and fewer residual pores.

Preparation of an Iron Oxide Modified Montmorillonite for Removal of Arsenic in Waters

Most concerns have focused on the arsenic (As) contamination in wastewater. Montmorillonite (MMT) has been proved to be a good adsorbent for removal heavy metals existing as cation in ground water while it is invalid for anions. However, arsenic usually exists as anions in aqueous. Accordingly, suitable modifications on MMT need to be done before using. This paper presents the results that a kind of commercial MMT has been modified by iron oxides under normal and inverse titration conditions. The x-ray diffraction (XRD), Thermal Gravimetry Analysis and Differential Thermal Analysis (TGA-DTA) and SBET analysis have been employed to elucidate the modification mechanisms. Modification characteristic analysis illustrated that the iron oxide associated with MMT by coated style as polymerization of hydroxyl-Fe (Fe (OH) 3) under inverse titration condition. Under normal titration condition, on the other hand, the iron oxide associated with MMT predominant by intercalation as goethite (FeOOH). The arsenic removal efficiencies of different modified products for polluted water have also been verified by batch experiments. Results proved that Iron oxide modified MMT on the removal efficiency of arsenic significantly increased and the normal titration is better than inverse titration as indicated by the arsenic removal ratios under the same experimental conditions. Based on these results, the iron oxide modified MMT by normal titration procedure is a promising material for removal arsenic in wastewaters.

Quetiapine Induced Acute Dystonia in a patient with History of severe Head Injury

A patient with a history of severe head injury 10 years ago regained ability to walk after years of being bound to a wheelchair. During the last psychiatric hospitalization, quetiapine was increased to therapeutic dose using a normal titration. As a result the patient developed dystonia of multiple muscle groups requiring 4 days of hospitalization for remittance of symptoms. In this paper, we take a close look at the literature concerning extrapiramidal symptoms (EPS) in this context, and we suggest that in patients with a history of head injury, it is warranted to consider a slower titration of antipsychotic medications, including ones that are considered having a lower risk of EPS such as quetiapine.

Synthesis of LiFePO4 using FeSO4·7H2O byproduct from TiO2 production as raw material

As the byproduct of TiO2 industrial production, impure FeSO4·7H2O was used for the synthesis of LiFePO4. With the purified solution of FeSO4·7H2O, FePO4·xH2O was prepared by a normal titration method and a controlled crystallization method, respectively. Then LiFePO4 materials were synthesized by calcining the mixture of FePO4·xH2O, Li2CO3, and glucose at 700°C for 10 h in flowing Ar. The results indicate that the elimination of FeSO4·7H2O impurities reached over 95%, and using FePO4·xH2O prepared by the controlled crystallization method, the obtained LiFePO4 material has fine and sphere-like particles. The material delivers a higher initial discharge specific capacity of 149 mAh·g−1 at a current density of 0.1C rate (1C = 170 mA·g−1); the discharge specific capacity also maintains above 120 mAh·g−1 after 100 cycles even at 2C rate. Thus, the employed processing is promising for easy control, low cost of raw material, and high electrochemical performance of the prepared material.

Autonomic Activity during Desflurane Anesthesia in Patients with Brain Tumors

Although intracranial tumors may affect autonomic function, there are few reports of autonomic changes during anesthesia. The purpose of this study was to evaluate autonomic effects of anesthesia in patients with brain tumors compared to neurosurgical controls. Two groups were evaluated: group 1 = 10 neurosurgical patients undergoing spinal cord surgery, group 2 = 10 patients with intracranial tumors. After placement of electrocardiogram and Response Entropy electroencephalogram (EEG) electrodes, 10 min baseline measures were made. Heart periods were transformed into a percentage index and heart rate entropy determined as a measure of variance of autonomic activity. Tone was evaluated as the balance between accelerator and inhibitory activity. Tone-entropy was measured during propofol anesthetic induction and the first 60 min of desflurane anesthesia before the start of surgery. Blood pressure and heart rate were similar between the groups. Starting at awake levels, vagal heart tone was observed. Anesthesia decreased vagal dominance to near zero in both groups. Heart rate entropy and EEG activity decreased during anesthesia with no significant difference between the groups. Desflurane concentrations required to maintain anesthesia were significantly lower in patients in brain tumors. Tone-entropy analysis of heart rate indicates anesthetic related depression of autonomic activity with no difference between groups. Normal titration of desflurane concentrations to maintain adequate blood pressure produced desflurane requirements that were lower in patients with brain tumors, while autonomic and EEG activity were similar.

Research on Preparation of Zr(OH) 4/B 4C Composite Powder by Different Processes

B 4C, ZrOCl 2 · 8H 2O, and dilute ammonia were used as experimental materials to study the characteristics of Zr(OH) 4-coated B 4C synthesized by normal titration, reversing titration and hydrolysis. The effects of titration speed and pH value on the coating results of composite powders, and the effect of pre-calcination temperature on the composition of composite powders were studied. The study results indicated that the optimal effect of Zr(OH) 4-coated B 4C could be obtained by normal titration. In normal titration, the optimal effect could be obtained when the titration speed was 1 ml · min −1 and the pH value was 9. Adding Y 2O 3 could promote the formation of ZrB 2. At the pre-calcination temperature of 1300 °C × 1 h, Zr(OH) 4/B 4C powder turned into ZrB 2/B 4C composite powder.

Differential electrolytic potentiometric titration method for the determination of ciprofloxacin in drug formulations

A simple and rapid differential electrolytic potentiometric titration method for the determination of ciprofloxacin was developed. The work is based on the fast complexation reaction between iron(III) and ciprofloxacin in a ratio of 1:3, respectively, in sulfuric acid media of 0.09 mol dm −3. Among the electrodes tested silver amalgam electrodes were found to be a suitable indicating system. By applying a current density of 0.5 μA cm −2 to these electrodes and using iron(III) solution of 0.097 mol dm −3 as a titrant, normal titration curves were obtained. The method was successfully applied for the determination of ciprofloxacin in drug formulations as low as 4.0 ppm.

Diaphragm-Free Cell for Trace Determination of Water Based on the Karl Fischer Reaction Using Continuous Coulometric Titration

A new type of diaphragm-free coulometric cell for continuous coulometric Karl Fischer titrations of water in the range 0.1-1000 μg is described. The relative standard deviation obtained for titrations of 1 μg amounts of water was typically 1%. The background due to diffusion of water from the air was normally in the range 0.3-0.9 μg of water min(-1) depending on environmental humidity. The variation in the background was normally ±0.01 μg min(-1). The construction makes it possible, at any time in a sequence of titrations, to renew the catholyte by means of a Teflon plunger inside the cathode compartment. In this way, the interference effects caused by oxidizable reduction products of methyl sulfite which are formed at the cathode can be controlled in a very simple way. These products are rapidly eliminated by means of a normal titration before a new titration starts. The need for this draining step differs depending on the type of reagent used. The coulometric titration system makes use of true potentiometric end-point detection, and this principle makes it possible to control the iodine level at the end-point at much lower levels as compared with commercial instrumentation. The analytical advantages gained by this option are demonstrated for the determination of water in ethylenediamine, a task which was found to be impossible when using end-point concentrations in the range (3-7) × 10(-5) M, which is typical for the bipotentiometric indicating system used in commercial instruments. Recovery rates in the range 100-102% were obtained and are shown to be dependent on the type of reagent used. The most accurate results were obtained for an imidazole-buffered methanolic reagent in which the concentration of sulfur dioxide was kept relatively low (0.10 M). The diaphragm-free cell described was shown to be compatible with all of the commercial reagents (designed for coulometry) investigated, including the well-known Hydranal products Coulomat A, AK, AG, AG-H, and AD.

Enthalpies of solution of polyvinylacetate in chloroform, acetone, and methanol using titration calorimetry

Heats of mixing of the solvents chloroform, methanol, and acetone with their solutions in polyvinylacetate have been measured at 25°C using a titration calorimeter. Titration of pure solvent to solutions as well as titration of solutions to the pure solvent or to diluted solutions have been performed. The second method, called ‘reverse titration’, proved to be more sensitive than normal dilution titration at sufficiently low polymer concentration. Equations describing the relative sensitivity of both titration methods have been developed. The concentration range covered by the experiments is restricted to volume fractions of polyvinylacetate not higher than 0.1–0.15 due to the high viscosities of concentrated solutions. The interaction parameterXH of the Flory-Huggins theory has been determined from the calorimetric data.XH is positive for methanol solutions and negative for chloroform and acetone solutions reflecting endothermic and exothermic heat effects respectively.

1H-NMR investigation of yeast cytochrome c. interaction with the corresponding specific reductase (L-lactate cytochrome)

1H-NMR spectroscopy has been used to study the modifications of certain characteristic resonances of the Hansenula anomala yeast cytochrome c on binding to its specific reductase (flavocytochrome b 2) or to the isolated cytochrome domain obtained from the entire molecule. Normal titration curves are observed for the resonances at 37.8 ppm assigned to heme c methyl 8 and at 19.4 ppm, line of cytochrome b 2 spectrum. In contrast, the shifts near 3.2 and 3.4 ppm for trimethyl-lysine resonances of this cytochrome c present abnormal titration curves, saturation being apparently reached at low molar (cytochrome b 2)/(cytochrome c) ratio. An interpretation is proposed in terms of shifts due to local conformational transitions induced by reductase binding but not rapidly reversible upon dissociation.

Antimycin binds to a small subunit of the ubiquinol: cytochrome c oxidoreductase

Bovine heart ubiquinol: cytochrome c oxidoreductase in Triton X-100 is split with guanidine into a number of fractions. A new method for measuring antimycin binding is developed using extraction with pentanol of the reversibly bound antimycin. By this method and the normal titration method, antimycin-binding capacity is found in a fraction containing a small subunit with a molecular mass of about 12000. This polypeptide was associated with cytochrome c 1 but is probably not the ‘hinge protein’. Fractions that contain cytochrome b did not show binding by the pentanol-extraction method.

A desk-computer program for gran plots

The GRAN program described is designed to run on a desck computer with 32 kbyte of memory. It can plot normal titration curves (potential vs. volume) and Gran function vs. volume curves for various procedures involving selective electrodes.

Stability and physicochemical properties of a trypsin inhibitor from winged bean seed ( psophocarpus tetragonolobus (L)DC)

The stability and physicochemical properties of the major trypsin inhibitor from the winged bean seed (designated trypsin inhibitor 2) have been studied in solution. The purified inhibitor, which stoichiometrically inhibits bovine trypsin in the molar ratio 1:1, is stable over the pH range 3–11 at ambient temperatures. Only a slight decrease in inhibitory activity occurs down to pH 2, but a sharper decrease occurs at pH values above 11. The inhibitor is stable to heat up to 60°C, but at higher temperatures (60–90°C) it is more stable at pH 3 than at pH 5.5 or pH 8.0. Trypsin inhibitor 2 retains its inhibitory activity in 8 M urea at pH 8.0, but is more susceptible to 8 M urea at pH 4.0. The stronger denaturant 6 M guanidine hydrochloride, however, abolishes the inhibitory activity at both pH 4.0 and pH 8.0. The inhibitor was not inactivated in 0.14 M β-mercaptoethanol at either pH; however, reduction in the presence of 8 M urea or 6 M guanidine hydrochloride results in a loss of inhibitory activity. Circular dichroism and optical rotatory dispersion studies indicate that the inhibitor structure is characterized by β-sheet and unordered forms and the absence of α-helix. The positive CD band centered at 227 nm has been used to follow conformation change as a function of temperature. In line with the stability studies, the inhibitor conformation was thermally most stable at pH 3.0 and changed increasingly as the pH was raised. This band showed little change at neutral pH up to 8 M guanidine hydrochloride. Tyrosine titration in aqueous solution indicates that 1 or 2 of the 11 tyrosines are difficult to titrate even at pH 13. A more normal titration curve is obtained in 6 M guanidine hydrochloride, although at least one tyrosine side-chain appears to be buried in the protein interior and resists complete titration at pH values in excess of 12. These data show that this inhibitor has a high degree of stability, typical of other known protein proteinase inhibitors.

Activation and inactivation of purified acetylcholinesterase from Electrophorus electricus by lanthanum(III)

The effects of LaCl 3 on the kinetic properties of soluble acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) from Electrophorus electricus were reinvestigated in the light of a report (Marquis, J.K. and Webb, G.D. (1977) Mol. Cell. Biochem. 16, 31–36) that the La(III) ion exerts a dual effect on the enzyme, described as a delayed activation superimposed on a near-instantaneons inhibition of acetylcholine hydrolysis. In the present study we demonstrate that activation of the rate of acetylthiocholine hydrolysis in a low ionic strength medium is a rapid process and in this sense La 3+ resembles other activating metal ions such as Ca 2,+ and Mg 2+. Prolonged exposure of the enzyme to La 3,+ resulted in a progressive decrease in the rate of acetylthiocholine hydrolysis. Measurement of the amplitude of the ‘burst’ phase of the reaction of enzyme with the carbamoylating reagent 7-(dimethylcarbamoyloxy)- N-methylquinolinium iodide showed that the latter effect was due to the conversion of enzyme to an ‘unreactive’ species, similar to that produced by Zn 2+ and certain other heavy metal ions. The La 3+ titration curve was biphasic and spread over several orders of magnitude of LaCl 3 concentration under conditions of low ionic, strength. Normal titration behaviour was observed at high ionic strength. These results are consistent with a simple model involving ‘active’, ‘activated’ and ‘unreactive’ states of the enzyme. The distribution of enzyme among these forms is dependent upon the binding of metal ions to distinct classes of activator and inactivator binding sites.

Conformation prediction and spectral studies on adrenodoxin. The accessibility of the tyrosine residue at position 82 in the polypeptide.

The nature and accessibility of Tyr 82 were studied by fluorimetry and ultraviolet spectroscopy. A strongly emitting residue was indicated by the fluorescence yield measurement. Lowering of fluorescence yield in the presence of guanidine may be suggestive of the location of the tyrosine residue in a helical environment. The addition of external quenchers, Cs+, I-, and phosphate, to adrenodoxin lowered its fluorescence intensity showing the accessibility of Tyr 82. For solvent perturbation studies using ethylene glycol and polyethylene glycol as perturbants, spectral changes were induced in adrenodoxin which gave rise to difference spectra attributable to the tyrosine residue. In addition, the spectrophotometric titration of tyrosine in adrenodoxin showed a normal titration curve with an estimated pK of 10.4. These results can be explained in terms of an accessible tyrosine residue that is partially blocked from solute and solvent perturbation. The secondary structure of adrenodoxin was studied by the method of Chou and Fasman (Chou, P. Y., and Fasman, G. D. (1978) Annu. Rev. Biochem. 47, 251-276) for the empirical predictions of protein conformations. The prediction shows a protein with moderately high amount of ordered structures (25% alpha-helix and 37% beta-sheet) and the tyrosine residue at position 82 in a helical environment.

Time resolved spectroscopy of tryptophyl fluorescence of yeast 3-phosphoglycerate kinase.

The tryptophyl fluorescence emission of yeast 3-phosphoglycerate kinase decreases from pH 3.9 to pH 7.2 following a normal titration curve with an apparent pK of 4.7. The fluorescence decays have been determined at both extreme pH by photocounting pulse fluorimetry and have been found to vary with the emission wavelength. A quantitative analysis of these results according to a previously described method allows to determine the emission characteristics of the two tryptophan residues present in the protein molecule. At pH 3.9, one of the tryptophan residues is responsible for only 13% of the total fluorescence emission. This first residue has a lifetime tau 1 = 0.6 ns and a maximum fluorescence wavelength lambda 1max = 332 nm. The second tryptophan residue exhibits two lifetimes tau 21 = 3.1 ns and tau 22 = 7.0 ns (lambda 2max = 338 nm). In agreement with the attribution of tau 21 and tau 22 to the same tryptophan residue, the ratio beta = C21/C22 of the normalized amplitudes is constant along the fluorescence emission spectrum. At pH 7.2, the two tryptophan residues contribute almost equally to the protein fluorescence. The decay time of tryptophan 1 is 0.4 ns. The other emission parameters are the same as those determined at pH 3.9. We conclude that the fluorescence quenching in the range pH 3.9 to pH 8.0 comes essentially from the formation of a non emitting internal ground state complex between the tryptophan having the longest decay tie equilibrium constant of the internal complex can be estimated. The quenching group is thought to be a carboxylate anion. Excitation transfers between the two tryptophyl residues of the protein molecule appear to have a small efficiency.