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Article: The use of approximation formulae in calculations of acid-base equilibria.

Machado, A A

2006 Volume 27, Issue 12, Page(s) 1099–1101

Abstract: Details of diagrams recently presented for the regions where approximation formulae give the pH of mono- and diprotic acids with an error of less than 0.02 pH unit are discussed. ...

Abstract	Details of diagrams recently presented for the regions where approximation formulae give the pH of mono- and diprotic acids with an error of less than 0.02 pH unit are discussed.
Language	English
Publishing date	2006-01-23
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	1500969-5
ISSN	1873-3573 ; 0039-9140
ISSN (online)	1873-3573
ISSN	0039-9140
DOI	10.1016/0039-9140(80)80259-1
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Article: An automatic system for determining the effects of temperature on the hysteresis curves of ion-selective electrodes.

Magalhães, J M / Machado, A A

The Journal of automatic chemistry

2007 Volume 19, Issue 2, Page(s) 39–44

Abstract: This paper describes an automatic system which measures the effect of temperature variations on the response of ion-selective electrodes (hysteresis curves). The system is managed by a computer program which plots hysteresis curves following a pre- ... ...

Abstract	This paper describes an automatic system which measures the effect of temperature variations on the response of ion-selective electrodes (hysteresis curves). The system is managed by a computer program which plots hysteresis curves following a pre-established temperature cycle, from setting and controlling the temperature of the water-bath, to acquiring the response potentials of up to five electrodes after temperature stabilization.
Language	English
Publishing date	2007-12-28
Publishing country	England
Document type	Journal Article
ZDB-ID	431456-6
ISSN	0142-0453 ; 1463-9246
ISSN	0142-0453 ; 1463-9246
DOI	10.1155/S1463924697000060
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Article: Simultaneous determination of the acid and basic ionization constants of imidazole.

Vasconcelos, M T / Machado, A A

Talanta

2006 Volume 33, Issue 11, Page(s) 919–922

Abstract: The acid and base ionization constants of imidazole (LH) have been determined simultaneously by potentiometry. Concentration constants were obtained at 10.0, 15.0, 25.0 and 40.0 degrees with I = 0.1M (KNO(3)), the values (and standard deviations) at 25.0 ...

Abstract	The acid and base ionization constants of imidazole (LH) have been determined simultaneously by potentiometry. Concentration constants were obtained at 10.0, 15.0, 25.0 and 40.0 degrees with I = 0.1M (KNO(3)), the values (and standard deviations) at 25.0 degrees being pK(a1)(LH(2)(+)) = 7.002 +/- 0.006 and pK(a2)(LH(2)(+)) = 12.588 +/- 0.004. The following values were obtained for the corresponding thermodynamic parameters: DeltaH(1) =38 and DeltaH(2) = 38 kJ mole DeltaS(1) = -8 and DeltaS(2)= -112 J.mole(-1).K(-1).
Language	English
Publishing date	2006-01-23
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	1500969-5
ISSN	1873-3573 ; 0039-9140
ISSN (online)	1873-3573
ISSN	0039-9140
DOI	10.1016/0039-9140(86)80225-9
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Article: Acid-base ionization equilibria of 1-(2-carbamylethyl) imidazole and its 2-methyl and 2-ethyl derivatives.

Vasconcelos, M T / Machado, A A

Talanta

2006 Volume 34, Issue 5, Page(s) 525–527

Abstract: The acid and base ionization constants of 1-(2-carbamylethyl)-2-alkylimidazoles, as well as the acid ionization constants of acrylamide and acetamide, have been determined by potentiometry. Concentration constants at 10.0, 25.0 and 40.0 degrees and I = 0. ...

Abstract	The acid and base ionization constants of 1-(2-carbamylethyl)-2-alkylimidazoles, as well as the acid ionization constants of acrylamide and acetamide, have been determined by potentiometry. Concentration constants at 10.0, 25.0 and 40.0 degrees and I = 0.1M (KNO(3)) were measured. From plots of log K vs. 1/T the thermodynamic parameters (DeltaH and DeltaS) of the ionization reactions were calculated.
Language	English
Publishing date	2006-01-23
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	1500969-5
ISSN	1873-3573 ; 0039-9140
ISSN (online)	1873-3573
ISSN	0039-9140
DOI	10.1016/0039-9140(87)80176-5
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Conference proceedings ; Online: Cyclic Depositional Processes on a Mixed System in Northern Campos Basin, SE Brazil

Pandolpho, Bruna Teixeira / Klein, A. H. da Fontoura / Dutra, I. / Mahiques, M. / Viana, A. R. / Bueno, G. V. / Machado, A. A. / Camargo, Y. L. / Hercos, C. M. / Lima, Y. / Filho, A. F. H. F. / Theodoro, C. E.

2021

Abstract: A new mixed turbidite-contourite system is described in the northern Campos Basin, southeastern Brazilian margin. This system is developed in a middle slope setting and was formed through non-synchronous interaction between the turbidity current and a ... ...

Abstract	A new mixed turbidite-contourite system is described in the northern Campos Basin, southeastern Brazilian margin. This system is developed in a middle slope setting and was formed through non-synchronous interaction between the turbidity current and a contour current in the same stratigraphic interval (Miocene). Different depositional cycles were accounted based on their diagnostic seismic features. Seismic attributes, seismic facies, and isochron maps were used to identify alternating cycles of downslope and alongslope processes in the study area, along with the intermediate stage with features from both processes (mixed system). The depositional processes resulted from alongslope current activity can be distinguished from the downslope current activity, based on the acoustic characteristics (root-mean-square (RMS) amplitude), internal architecture, and external geometry pattern. While alongslope currents deposits consist of mainly low RMS amplitude values clinoforms with an alongslope trend; the downslope gravity deposits present high-amplitude or chaotic seismic facies, usually higher values of RMS amplitude, channel or channel-lobe features, erosive surfaces, and a basinward depositional trend. In this study, five seismic units are described and later associated with their dominant type of current. Based on the main depositional diagnostic features, it was possible to determine which were the dominant processes that controlled the sedimentation by indicating periods where the margin was mostly submitted to sediment transfer from continent to the basin and periods wherethe oceanic currents prevailed by redistributing sediments along the isobaths and replacing the axis of downslope transfer conduits. Important information on the paleocurrents' direction was also made based on the final deposits display (e.g. terraces, sediment waves, paleochannels), a northward-flowing bottom current was assumed. Research on alternating dominant processes and mixed depositional systems may provide a better understanding of ...
Subject code	550
Publishing country	de
Document type	Conference proceedings ; Online
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Article ; Online: Assessment of indicators of vitamin A status in non-cirrhotic chronic hepatitis C patients.

Santana, R C / Machado, A A / Martinelli, A L C / Jordão, A A / Ramalho, L N Z / Vannucchi, H

Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas

2016 Volume 49, Issue 1, Page(s) e4785

Abstract: Subjects with chronic liver disease are susceptible to hypovitaminosis A due to several factors. Therefore, identifying patients with vitamin deficiency and a requirement for vitamin supplementation is important. Most studies assessing vitamin A in the ... ...

Abstract	Subjects with chronic liver disease are susceptible to hypovitaminosis A due to several factors. Therefore, identifying patients with vitamin deficiency and a requirement for vitamin supplementation is important. Most studies assessing vitamin A in the context of hepatic disorders are conducted using cirrhotic patients. A cross-sectional study was conducted in 43 non-cirrhotic patients with chronic hepatitis C to evaluate markers of vitamin A status represented by serum retinol, liver retinol, and serum retinol-binding protein levels. We also performed the relative dose-response test, which provides an indirect estimate of hepatic vitamin A reserves. These vitamin A indicators were assessed according to the stage of liver fibrosis using the METAVIR score and the body mass index. The sample study was predominantly composed of male subjects (63%) with mild liver fibrosis (F1). The relative dose-response test was <20% in all subjects, indicating vitamin A sufficiency. Overweight or obese patients had higher serum retinol levels than those with a normal body mass index (2.6 and 1.9 µmol/L, respectively; P<0.01). Subjects with moderate liver fibrosis (F2) showed lower levels of serum retinol (1.9 vs 2.5 µmol/L, P=0.01) and retinol-binding protein levels compared with those with mild fibrosis (F1) (46.3 vs 67.7 µg/mL, P<0.01). These results suggested an effect of being overweight on serum retinol levels. Furthermore, more advanced stages of liver fibrosis were related to a decrease in serum vitamin A levels.
MeSH term(s)	Adult ; Aged ; Biomarkers/analysis ; Biopsy ; Body Mass Index ; Cross-Sectional Studies ; Dietary Supplements ; Dose-Response Relationship, Drug ; Female ; Hepatitis C, Chronic/complications ; Humans ; Liver/chemistry ; Liver Cirrhosis/pathology ; Male ; Middle Aged ; Organ Dysfunction Scores ; Overweight/blood ; Retinol-Binding Proteins/analysis ; Vitamin A/analysis ; Vitamin A Deficiency/complications ; Vitamin A Deficiency/diagnosis ; Young Adult
Chemical Substances	Biomarkers ; Retinol-Binding Proteins ; Vitamin A (11103-57-4)
Language	English
Publishing date	2016-01
Publishing country	Brazil
Document type	Journal Article
ZDB-ID	786234-9
ISSN	1414-431X ; 0100-879X
ISSN (online)	1414-431X
ISSN	0100-879X
DOI	10.1590/1414-431X20154785
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Article: Trehalose as a cryoprotectant in freeze-dried wheat sourdough production

Stefanello, R. F. / Machado, A. A. R. / Cavalheiro, C. P. / Santos, M. L. B. / Nabeshima, E. H. / Copetti, M. V. / Fries, L. L. M.

LWT - food science and technology

2018 Volume 89, Issue -, Page(s) 510

Language	English
Document type	Article
ZDB-ID	2169058-3
ISSN	0023-6438
Database	Current Contents Nutrition, Environment, Agriculture

In stock of ZB MED Bonn / Germany

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Article: A combination of synchronous fluorescence spectroscopy with chemometric treatment and internal standards in non-aqueous potentiometric titrations of fulvic acids.

Esteves da Silva, J C / Machado, A A

Talanta

2006 Volume 41, Issue 12, Page(s) 2095–2104

Abstract: The acid properties of a soil fulvic acid (sfua) were characterized by potentiometric titration with tetrabutylammonium hydroxide in two non-aqueous solvents with high acid-base resolution power N,N-dimethylformamide (DMF) and acetonitrile. Synchronous ... ...

Abstract	The acid properties of a soil fulvic acid (sfua) were characterized by potentiometric titration with tetrabutylammonium hydroxide in two non-aqueous solvents with high acid-base resolution power N,N-dimethylformamide (DMF) and acetonitrile. Synchronous fluorescence spectroscopy (SyF) was also used to monitor directly the sfua status during the potentiometric titration in DMF. The potentiometric titration curves showed no clear end-point and the analysis of the sets of spectra obtained at increasing neutralization degree, with a self-modeling curve resolution method (SIMPLISMA), revealed the existence of two components with featureless concentration profiles. Internal standards (maleic, salicylic and p-hydroxylbenzoic acids) were used to determine the amounts of acid groups with different acid strengths in the two non-aqueous solvents. It was shown that the variations observed in the SyF spectra sets of the internal standards are not correlated with those observed in the sfua data. The splitting of the sfua groups in the non-aqueous titration curves seems to be forced artificially depending on the standards used.
Language	English
Publishing date	2006-01-23
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	1500969-5
ISSN	1873-3573 ; 0039-9140
ISSN (online)	1873-3573
ISSN	0039-9140
DOI	10.1016/0039-9140(94)00185-5
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Article ; Online: Restless legs syndrome in Wilson's disease: frequency, characteristics, and mimics.

Trindade, M C / Bittencourt, T / Lorenzi-Filho, G / Alves, R C / de Andrade, D C / Fonoff, E T / Bor-Seng-Shu, E / Machado, A A / Teixeira, M J / Barbosa, E R / Tribl, G G

Acta neurologica Scandinavica

2017 Volume 135, Issue 2, Page(s) 211–218

Abstract: Objective: To determine characteristics, clinical significance, frequency, and mimics of restless legs syndrome (RLS) in a cohort of Wilson's disease (WD, n = 42/f = 18), compared to healthy, matched controls.: Materials and methods: Structured ... ...

Abstract	Objective: To determine characteristics, clinical significance, frequency, and mimics of restless legs syndrome (RLS) in a cohort of Wilson's disease (WD, n = 42/f = 18), compared to healthy, matched controls. Materials and methods: Structured clinical interviews (patients and caregiving family members), repeated neurological examinations (afternoon and presleep), comprehensive laboratory tests, WD-, RLS-, and sleep-specific rating scales, and video-polysomnography. Results: Thirteen patients with WD (13/42 = 31.0%) clearly fulfilled the five diagnostic criteria of RLS; in eight patients (19.1%), the burden of RLS was clinically significant. The RLS was of moderate severity, equally distributed among sexes, manifested mainly in the evening and before falling asleep, and had developed mostly after clinical manifestation of WD (time elapsed 10.2 ± 14.5 years), still at a young mean age (27.5 ± 11.5 years). The known RLS-associated features were absent (normal iron and kidney parameters) or rare (positive family history, polyneuropathy). Compared to WD patients without RLS, patients with RLS were significantly elder and had suffered longer from WD. WD-specific RLS mimics as well as RLS confounding motor comorbidities (dystonia, tremor, chorea) were frequent and a diagnostic challenge; in difficult cases, the differentiation was reached by clinical observation of the motor behavior in the evening or at nighttime. Conclusion: RLS was frequent in this cohort of WD and might be causally related to WD. RLS should be included in the diagnostic work-up of WD. In complex motor disorders, differential diagnosis of RLS might require evening/nighttime examination and video-polysomnography. In WD patients with a clinically significant RLS, treatment with dopaminergic substances may be considered.
MeSH term(s)	Adolescent ; Adult ; Cohort Studies ; Comorbidity ; Diagnosis, Differential ; Dystonic Disorders/diagnosis ; Dystonic Disorders/epidemiology ; Female ; Hepatolenticular Degeneration/diagnosis ; Hepatolenticular Degeneration/epidemiology ; Humans ; Male ; Middle Aged ; Neurologic Examination/methods ; Polysomnography/methods ; Restless Legs Syndrome/diagnosis ; Restless Legs Syndrome/epidemiology ; Sleep/physiology ; Tremor/diagnosis ; Tremor/epidemiology ; Young Adult
Language	English
Publishing date	2017-02
Publishing country	Denmark
Document type	Journal Article
ZDB-ID	90-5
ISSN	1600-0404 ; 0001-6314
ISSN (online)	1600-0404
ISSN	0001-6314
DOI	10.1111/ane.12585
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Article: Urea potentiometric biosensor based on urease immobilized on chitosan membranes.

Magalhães, J M / Machado, A A

Talanta

1998 Volume 47, Issue 1, Page(s) 183–191

Abstract: Potentiometric biosensors based on urease (E.C. 3.5.1.5.) immobilized on chitosan membranes coupled to all-solid-state nonactin ammonium ion selective electrodes are described. The enzyme was immobilized on the chitosan membranes by four procedures: (A) ... ...

Abstract	Potentiometric biosensors based on urease (E.C. 3.5.1.5.) immobilized on chitosan membranes coupled to all-solid-state nonactin ammonium ion selective electrodes are described. The enzyme was immobilized on the chitosan membranes by four procedures: (A) adsorption; (B) adsorption followed by reticulation with dilute aqueous glutaraldehyde solution; (C) activation with glutaraldehyde followed by contact with the enzyme solution; and (D) activation with glutaraldehyde, contact with the enzyme solution and reduction of the Schiff base with sodium borohydride. The response characteristics of the biosensors obtained with these enzymatic membranes were determined and compared. The biosensor with best response characteristics, obtained by procedure (B), showed the following characteristics of response to urea: (i) linearity in the 10(-4) to 10(-2) M range; (ii) slope of up to 56 mV per decade; (iii) response time between 30 s and 2 min; and (iv) lifetime of 2 months. This biosensor was tested in the determination of urea in blood serum samples.
Language	English
Publishing date	1998-09
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	1500969-5
ISSN	1873-3573 ; 0039-9140
ISSN (online)	1873-3573
ISSN	0039-9140
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