Performance Evaluation of CEA Assay on Beckman Coulter UniCel DxI 800

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S20-S20
Author(s):  
Qing Wei ◽  
Robert Hardy ◽  
Liyun Cao
Keyword(s):  
Reference Range ◽  
Limit Of Detection ◽  
Measurement Range ◽  
Surgical Removal ◽  
Primary Colorectal Cancer ◽  
Serum Cea ◽  
The Mean ◽  
Precision And Accuracy ◽  
Patient Prognosis ◽  
High Level

Abstract Carcinoembryonic antigen (CEA) is a glycoprotein normally found in embryonic entodermal epithelium. Increased levels may be found in patients with primary colorectal cancer or other malignancies. CEA levels are not useful in screening the general population for undetected cancers. However, CEA levels provide important information about patient prognosis, recurrence of tumors after surgical removal, and effectiveness of therapy. The aim of this study was to assess the analytical performance of CEA assay on a Beckman Coulter UniCel DxI 800. The linearity, sensitivity, reference range, precision, and accuracy were evaluated following CLSI guidelines. The within-run and between-run precisions were assessed by analyzing QC material at low and high levels of concentrations. The accuracy was assessed by comparison of 152 patient serum CEA on DXI with CEA on a previously established ADVIA Centaur System. The analytical measurement range was determined to be linear between 0.00 and 951.3 ng/mL with a slope of 0.976 and intercept of 0.075. The limit of blank (LOB) was determined as 0.03 ng/mL and the limit of detection (LOD) was 0.1 ng/mL. The reference range was verified as 0.0 to 3.0 ng/mL (nonsmokers) and 0.0 to 5.0 ng/mL (smokers). The within-run CVs for CEA were 4.4% at the low level of 2.239 ng/mL and 2.5% at the high level of 38.1 ng/mL. The between-run CVs at low and high levels were 4.4%, and 4.0%, respectively. Comparison of CEA on the Beckman Coulter UniCel DxI 800 with CEA on the ADVIA Centaur System of 152 patient samples showed the slope was 1.541 (95% CI, 1.515-1.567) with an intercept of 0.17 and a correlation coefficient of 0.9943 (Deming). The mean bias between Beckman and ADVIA was 6.49 (41.71%). In summary, our data demonstrate that CEA assay on the Beckman Coulter UniCel DxI 800 has good linearity and precision. There is also good correlation between CEA tested on the Beckman Coulter UniCel DxI 800 and on the ADVIA Centaur System with a positive bias.

Verification of Access OV Monitor (Cancer Antigen 125) Assay on Beckman Coulter Unicel DXI 800

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S82-S83
Author(s):  
Eric Ollila ◽  
Liyun Cao ◽  
Robert Hardy
Keyword(s):  
Correlation Coefficient ◽  
Reference Range ◽  
Measurement Range ◽  
Response To Therapy ◽  
Ca 125 ◽  
Cancer Antigen 125 ◽  
Comparison Results ◽  
Deming Regression ◽  
The Mean ◽  
High Concentrations

Abstract CA 125 levels are increased in ovarian carcinoma and other benign and malignant conditions. Levels are used to monitor response to therapy and disease progression. The objective of this study was to assess the analytical performance of the Access OV Monitor assay on the Beckman Coulter DXI. CA 125 was quantitatively determined on Beckman Coulter DXI following CLSI guidelines. Performance was evaluated for linearity, sensitivity, reference range, and precision. Within-run and between-run precisions were assessed by analyzing QC material at low and high concentrations. Accuracy was assessed by comparing 147 consecutive values with the previously established Siemens ADVIA Centaur XP. Antigen levels were classified as positive or negative based on the upper limit of the reference range to assess concordance between the two analyzers. The analytic measurement range was linear between 0.5 and 5,000 U/mL with a slope of 0.983 and intercept of 0.46. The reference range was 0 to 35 U/mL. Within-run CVs were 3.4% and 3.5% at low (53.81 U/mL) and high (392.78 U/mL) levels, respectively. Between-run CVs were 3.46% and 3.0% at low and high levels, respectively. The comparison results showed slope was 1.319 with an intercept of 12.61 and correlation coefficient of 0.9868 (Deming regression). The mean bias was 57.36 (33.98%). The correlation coefficient was 0.9633 and 0.9833 when CA 125 was negative and positive, respectively. The bias was 3.51 (25.73%) and 142.12 (34.41%) when CA 125 was negative and positive, respectively. The agreement was 94% (n = 138) and disagreement was 6% (n = 9). In conclusion, CA 125 on Beckman Coulter DXI has good linearity and precision and shows positive bias. There is good correlation and agreement between the two methods. Clinicians can reliably use the assay but should consider the potential bias when interpreting values near the upper end of the reference range.

Verification of Access GI Monitor (CA 19-9) Assay on Beckman Coulter Unicel DXI 800

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S19-S19
Author(s):  
Eric Ollila ◽  
Liyun Cao ◽  
Qing Wei ◽  
Mariam Youssef
Keyword(s):  
Correlation Coefficient ◽  
Reference Range ◽  
Clinical History ◽  
Gastrointestinal Diseases ◽  
Clinical Analysis ◽  
Measurement Range ◽  
Response To Therapy ◽  
Negative Results ◽  
Deming Regression ◽  
High Level

Abstract CA 19-9 antigen has been identified in patients with colorectal, pancreatic, bile duct, hepatocellular, stomach, and esophageal cancers. Noncancerous conditions that may elevate CA 19-9 levels include cirrhosis, cholangitis, hepatitis, pancreatitis, and nonmalignant gastrointestinal diseases. CA 19-9 antigen levels may be used as an aid in monitoring response to therapy or disease progression in cancer patients. The objective of this study was to assess the analytical performance of the Access GI Monitor assay on Beckman Coulter UniCel DXI 800. CA 19-9 was quantitatively determined on the Beckman Coulter UniCel DXI 800 following CLSI guidelines. The performance was evaluated for linearity, sensitivity, reference range, and precision. The within-run and between-run precisions were assessed by analyzing QC material at low and high levels of concentrations. Accuracy was assessed by comparison with the previously established Siemens ADVIA Centaur XP. Antigen level values were classified as positive or negative based on the upper limit of the reference range to assess concordance between the two analyzers. The accuracy of each analyzer was also assessed by correlating the discordant antigen values with the patients’ clinical history. For the Beckman Coulter DXI assay, the analytic measurement range was determined to be linear between 0.8 and 2,000 U/mL with a slope of 1.018 and intercept of 4.13. The limit of blank was determined as 0.09 U/mL. The reference range was verified as 0 to 35 U/mL. The within-run CVs for CA 19-9 were 3.7% at both the low level of 23.54 U/mL and high level of 262.56 U/mL. The between-run CVs at low and high levels were 4.34% and 6.36%, respectively. A total of 327 patient samples were analyzed in the comparison of CA 19-9 levels on Beckman Coulter DXI and Siemens ADVIA Centaur XP. On Deming regression, the slope was 0.665 with an intercept of 136.4 and correlation coefficient of 0.8964; there was wide scatter between the two methods. The mean bias between the two analyzers was –291.1 (–22.8%). The correlation coefficient was 0.8931, and the bias was –770.7 (–26.1%) when both were positive. The correlation coefficient was 0.7949, and the bias was –0.8 (–6.1%) when both were negative. The agreement of the two methods was 91% (n = 298) and disagreement was 9% (n = 29). After clinical analysis of 18 discordant values, six data points correlated better with the Siemens Centaur XP and the remaining 12 correlated better with the Beckman Coulter DXI. Our data demonstrate that CA 19-9 on Beckman Coulter DXI has good linearity and precision. There is poor to fair correlation between the two methods. Agreement based on clinical classification of positive and negative results is good. The Beckman Coulter DXI correlates with the patient clinical history better than the Siemens Centaur XP when comparing discordant values between the analyzers.

RADIOIMMUNOASSAY OF OESTRONE AND OESTRADIOL IN THE PERIPHERAL PLASMA OF THE DOMESTIC FOWL IN VARIOUS PHYSIOLOGICAL STATES AND OF HYPOPHYSECTOMIZED AND OVARIECTOMIZED FOWLS

1974 ◽  
Vol 75 (1) ◽  
pp. 133-140 ◽  
Author(s):  
B. E. Senior
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Diethyl Ether ◽  
Bovine Serum ◽  
Domestic Fowl ◽  
Laying Hens ◽  
Peripheral Plasma ◽  
The Mean ◽  
Precision And Accuracy ◽  
Chicken Ovary

ABSTRACT A radioimmunoassay was developed to measure the levels of oestrone and oestradiol in 0.5–1.0 ml of domestic fowl peripheral plasma. The oestrogens were extracted with diethyl ether, chromatographed on columns of Sephadex LH-20 and assayed with an antiserum prepared against oestradiol-17β-succinyl-bovine serum albumin using a 17 h incubation at 4°C. The specificity, sensitivity, precision and accuracy of the assays were satisfactory. Oestrogen concentrations were determined in the plasma of birds in various reproductive states. In laying hens the ranges of oestrone and oestradiol were 12–190 pg/ml and 29–327 pg/ml respectively. Levels in immature birds, in adult cockerels and in an ovariectomized hen were barely detectable. The mean concentrations of oestrone and oestradiol in the plasma of four non-laying hens (55 pg/ml and 72 pg/ml respectively) and one partially ovariectomized hen (71 pg/ml and 134 pg/ml respectively) were well within the range for laying hens. It is evident that the large, yolk-filled follicles are not the only source of oestrogens in the chicken ovary.

SERUM TRIIODOTHYRONINE DETERMINATION BY SATURATION ANALYSIS

1973 ◽  
Vol 72 (4) ◽  
pp. 714-726 ◽  
Author(s):  
A. Burger ◽  
B. Miller ◽  
C. Sakoloff ◽  
M. B. Vallotton
Keyword(s):  
Ionic Strength ◽  
Limit Of Detection ◽  
Improved Method ◽  
Accuracy Of Measurement ◽  
Tracer Amount ◽  
The Mean ◽  
Physiological Values ◽  
Hyperthyroid Patients ◽  
Solvent Blank

ABSTRACT An improved method for the determination of serum triiodothyronine (T3) has been developed. After addition of a tracer amount of the hormone, T3 was extracted from 1 ml serum under conditions of pH and ionic strength which favoured T3 extraction (89%) over thyroxine (T4) extraction (58%). Chromatography of the extracted material on Sephadex LH-20 separated T3 completely from residual T4. The T3 eluate was dried, then re-dissolved in 0.5 ml NaOH 0.04 n. To 0.2 ml duplicate aliquots, a standard amount of TBG was added for the competitive protein analysis. After one hour incubation at 4°C, separation of bound from free T3 was achieved on small Sephadex G-25 columns. Overall recovery was 67 ± 10.8% and correction for the loss was made. The solvent blank was 37 ± 27 (sd) ng/100 ml. Accuracy of measurement of known quantities of T3 added to serum was 98.4%. The coefficient of variation within the assay was 6.2% and between the assays it was 11.4%. The limit of detection (0.1 ng) corresponded to a concentration of 25 ng/100 ml. T4 added to serum did not interfere with T3 determination until high non-physiological values were reached. The mean ± sd serum T3 in 54 euthyroid subjects was 153 ± 58 ng/100 ml and in 24 hyperthyroid patients it was 428 ±186 ng/100 ml; 4 out of the 24 hyperthyroid values were within 2 sd of the mean euthyroid group. All the values found in the euthyroid group were well above the limit of detection of the method.

DFT Benchmark Study of the O--O Bond Dissociation Energy in Peroxides Validated with High-Level Ab-Initio Calculations

2019 ◽  
Author(s):  
Danilo Carmona ◽  
Pablo Jaque ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Reference Value ◽  
Basis Set ◽  
Basis Sets ◽  
Mean Deviation ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
The Mean ◽  
Experimental Values ◽  
High Level ◽  
Almost All

<div><div><div><p>Peroxides play a central role in many chemical and biological pro- cesses such as the Fenton reaction. The relevance of these compounds lies in the low stability of the O–O bond which upon dissociation results in radical species able to initiate various chemical or biological processes. In this work, a set of 64 DFT functional-basis set combinations has been validated in terms of their capability to describe bond dissociation energies (BDE) for the O–O bond in a database of 14 ROOH peroxides for which experimental values ofBDE are available. Moreover, the electronic contributions to the BDE were obtained for four of the peroxides and the anion H2O2− at the CBS limit at CCSD(T) level with Dunning’s basis sets up to triple–ζ quality provid- ing a reference value for the hydrogen peroxide anion as a model. Almost all the functionals considered here yielded mean absolute deviations around 5.0 kcal mol−1. The smallest values were observed for the ωB97 family and the Minnesota M11 functional with a marked basis set dependence. Despite the mean deviation, order relations among BDE experimental values of peroxides were also considered. The ωB97 family was able to reproduce the relations correctly whereas other functionals presented a marked dependence on the chemical nature of the R group. Interestingly, M11 functional did not show a very good agreement with the established order despite its good performance in the mean error. The obtained results support the use of similar validation strategies for proper prediction of BDE or other molecular properties by DF Tmethods in subsequent related studies.</p></div></div></div>

The way of value of Correlation of genomic DNA microsatellite loci and live weight of Chukchi reindeer

2020 ◽  
pp. 27-32
Author(s):  
V. Dodokhov ◽  
N. Pavlova ◽  
T. Rumyantseva ◽  
L. Kalashnikova
Keyword(s):  
Microsatellite Markers ◽  
Agricultural Production ◽  
Live Weight ◽  
Biodiversity Loss ◽  
Tribal Community ◽  
High Germination ◽  
Wide Range ◽  
The Mean ◽  
High Level ◽  
Dna Microsatellite

The article presents the genetic characteristic of the Chukchi reindeer breed. The object of the study was of the Chukchi reindeer. In recent years, the number of reindeer of the Chukchi breed has declined sharply. Reduced reindeer numbers could lead to biodiversity loss. The Chukchi breed of deer has good meat qualities, has high germination viability and is adapted in adverse tundra conditions of Yakutia. Herding of the Chukchi breed of deer in Yakutia are engaged only in the Nizhnekolymsky district. There are four generic communities and the largest of which is the agricultural production cooperative of nomadic tribal community «Turvaurgin», which was chosen to assess the genetic processes of breed using microsatellite markers: Rt6, BMS1788, Rt 30, Rt1, Rt9, FCB193, Rt7, BMS745, C 143, Rt24, OheQ, C217, C32, NVHRT16, T40, C276. It was found that microsatellite markers have a wide range of alleles and generally have a high informative value for identifying of genetic differences between animals and groups of animal. The number of identified alleles is one of the indicators of the genetic diversity of the population. The total number of detected alleles was 127. The Chukchi breed of deer is characterized by a high level of heterozygosity, and the random crossing system prevails over inbreeding in the population. On average, there were 7.9 alleles (Na) per locus, and the mean number of effective alleles (Ne) was 4.1. The index of fixation averaged 0.001. The polymorphism index (PIC) ranged from 0.217 to 0.946, with an average of 0.695.

Gamma knife radiosurgery in the management of cavernous sinus meningiomas

2000 ◽  
Vol 93 (supplement_3) ◽  
pp. 68-73 ◽  
Author(s):  
Pierre-Hugues Roche ◽  
Jean Régis ◽  
Henry Dufour ◽  
Henri-Dominique Fournier ◽  
Christine Delsanti ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Tumor Growth ◽  
Gamma Knife ◽  
Cavernous Sinus ◽  
Gamma Knife Radiosurgery ◽  
Surgical Removal ◽  
Content Type ◽  
Cavernous Sinus Meningioma ◽  
The Mean ◽  
Fine Print

Object. The authors sought to assess the functional tolerance and tumor control rate of cavernous sinus meningiomas treated by gamma knife radiosurgery (GKS). Methods. Between July 1992 and October 1998, 92 patients harboring benign cavernous sinus meningiomas underwent GKS. The present study is concerned with the first 80 consecutive patients (63 women and 17 men). Gamma knife radiosurgery was performed as an alternative to surgical removal in 50 cases and as an adjuvant to microsurgery in 30 cases. The mean patient age was 49 years (range 6–71 years). The mean tumor volume was 5.8 cm3 (range 0.9–18.6 cm3). On magnetic resonance (MR) imaging the tumor was confined in 66 cases and extensive in 14 cases. The mean prescription dose was 28 Gy (range 12–50 Gy), delivered with an average of eight isocenters (range two–18). The median peripheral isodose was 50% (range 30–70%). Patients were evaluated at 6 months, and at 1, 2, 3, 5, and 7 years after GKS. The median follow-up period was 30.5 months (range 12–79 months). Tumor stabilization after GKS was noted in 51 patients, tumor shrinkage in 25 patients, and enlargement in four patients requiring surgical removal in two cases. The 5-year actuarial progression-free survival was 92.8%. No new oculomotor deficit was observed. Among the 54 patients with oculomotor nerve deficits, 15 improved, eight recovered, and one worsened. Among the 13 patients with trigeminal neuralgia, one worsened (contemporary of tumor growing), five remained unchanged, four improved, and three recovered. In a patient with a remnant surrounding the optic nerve and preoperative low vision (3/10) the decision was to treat the lesion and deliberately sacrifice the residual visual acuity. Only one transient unexpected optic neuropathy has been observed. One case of delayed intracavernous carotid artery occlusion occurred 3 months after GKS, without permanent deficit. Another patient presented with partial complex seizures 18 months after GKS. All cases of tumor growth and neurological deficits observed after GKS occurred before the use of GammaPlan. Since the initiation of systematic use of stereotactic MR imaging and computer-assisted modern dose planning, no more side effects or cases of tumor growth have occurred. Conclusions. Gamma knife radiosurgery was found to be an effective low morbidity—related tool for the treatment of cavernous sinus meningioma. In a significant number of patients, oculomotor functional restoration was observed. The treatment appears to be an alternative to surgical removal of confined enclosed cavernous sinus meningioma and should be proposed as an adjuvant to surgery in case of extensive meningiomas.

scholarly journals AB0189 LIPOPROTEIN ABNORMALITIES IN RHEUMATOID ARTHRITIS PATIENTS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 1119.1-1119
Author(s):  
L. Nacef ◽  
Y. Besbes ◽  
Y. Mabrouk ◽  
H. Ferjani ◽  
K. Maatallah ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Demographic Data ◽  
Calcium Score ◽  
Healthy Person ◽  
Mean Value ◽  
Immunological Parameters ◽  
American College Of Rheumatology ◽  
Patient Consent ◽  
The Mean ◽  
High Level

Background:The lipid paradox is termed the decreased cholesterol level in rheumatoid arthritis (RA). Nevertheless, the apolipoprotein levels are usually higher than a healthy person and are predictors of cardiovascular events.Objectives:We aimed to describe lipid abnormalities in RA patients and to look for predictor factors of these changes.Methods:The prospective study was carried out on patients with RA who met the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria. These patients were followed in the rheumatology department of the Kassab Institute.We collected the socio-demographic data, biological and immunological parameters.The lipid assessment included: a measurement of total cholesterol (TC), HDL, LDL, and triglycerides (TG). Lipoproteins APOA1 and APOB were measured. All data were collected after patient consent.Results:Of the 47 patients recruited, 78.7% were female. The mean age was 52.5 ±11.06 [32-76]. The average RA progressed from 86.25 ±63 months [5-288] and was erosive in 81.6% of cases. The rheumatoid factor (RF) was positive in 57.8% of patients, and citrullinated antipeptide antibodies (ACPA) were present in 62.2%. Eight patients had a previous CV history.Mean TC was 4.42 ±1.3 [1.2-7.58], mean HDL was 1.38 ±0.73 [0.18-4.10], mean LDL was 2.55 ±1.16 [0.24-5.54]. The mean TG value was 1.28 ±0.6 [0.24-5.54]. TC elevation was found in 9.1% of cases, HDL in 21.3% of cases, LDL in 5.5% of cases, and TG in 16.4% of cases. Mean APOB/APOA1 ratio was 0.67 ±0.18 [0,46-1,11]. LDL elevation was associated to a high DAS28 (p=0.06, r=0.512). APOA1 was associated to a low DAS28 (p=0.04, r=-0.642).The mean value of APO A1 was 1.36 ±0.21 [0.84-1.81], that of APOB was 0.90 ±0.22 [0.58-1.40]. APOA1 values were lower in patients with high-level LDL (p=0.767). The APOB value was associated with lipid disturbance without significant correlation (p=0.291).Conclusion:Lipid test abnormalities can be found in RA patients outside of any known CV risk factors. APOA1 seems to have a protective effect. Screening and treatment of these abnormalities can prevent CV risk.References:[1]Miguel Bernardes and al. Coronary artery calcium score in female rheumatoid arthritis patients: Associations with apolipoproteins and disease biomarkers. Int J Rheum Dis. 2019;00:1–16.[2]Anna So dergren and al. Biomarkers associated with cardiovascular disease in patients with early rheumatoid arthritis. PLOS ONE. August 5, 2019.Disclosure of Interests:None declared

scholarly journals The Problems and Needs of Patients Diagnosed with Cancer and Their Caregivers

2020 ◽  
Vol 18 (1) ◽  
pp. 87
Author(s):  
Anna Lewandowska ◽  
Grzegorz Rudzki ◽  
Tomasz Lewandowski ◽  
Sławomir Rudzki
Keyword(s):  
Cancer Patients ◽  
Medical Information ◽  
Unmet Needs ◽  
Public Healthcare ◽  
Literature Analysis ◽  
The Public ◽  
The Mean ◽  
High Level ◽  
Patients Experience

(1) Background: As the literature analysis shows, cancer patients experience a variety of different needs. Each patient reacts differently to the hardships of the illness. Assessment of needs allows providing more effective support, relevant to every person’s individual experience, and is necessary for setting priorities for resource allocation, for planning and conducting holistic care, i.e., care designed to improve a patient’s quality of life in a significant way. (2) Patients and Methods: A population survey was conducted between 2018 and 2020. Cancer patients, as well as their caregivers, received an invitation to take part in the research, so their problems and needs could be assessed. (3) Results: The study involved 800 patients, 78% women and 22% men. 66% of the subjects were village residents, while 34%—city residents. The mean age of patients was 62 years, SD = 11.8. The patients received proper treatment within the public healthcare. The surveyed group of caregivers was 88% women and 12% men, 36% village residents and 64% city residents. Subjects were averagely 57 years old, SD 7.8. At the time of diagnosis, the subjects most often felt anxiety, despair, depression, feelings of helplessness (46%, 95% CI: 40–48). During illness and treatment, the subjects most often felt fatigued (79%, 95% CI: 70–80). Analysis of needs showed that 93% (95% CI: 89–97) of patients experienced a certain level of need for help in one or more aspects. (4) Conclusions: Patients diagnosed with cancer have a high level of unmet needs, especially in terms of psychological support and medical information. Their caregivers also experience needs and concerns regarding the disease. Caregivers should be made aware of the health consequences of cancer and consider appropriate supportive care for their loved ones.

scholarly journals The fate of Si and Fe while nuclear glass alters with steel and clay

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
C. Carriere ◽  
P. Dillmann ◽  
S. Gin ◽  
D. Neff ◽  
L. Gentaz ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Protective Layer ◽  
Glass Dissolution ◽  
A Value ◽  
Waste Forms ◽  
Controlling Mechanism ◽  
Geological Repository ◽  
The Mean ◽  
High Level ◽  
Initial Dissolution Rate

AbstractThe French concept developed to dispose high-level radioactive waste in geological repository relies on glassy waste forms, isolated from the claystone host rock by steel containers. Understanding interactions between glass and surrounding materials is key for assessing the performance of a such system. Here, isotopically tagged SON68 glass, steel and claystone were studied through an integrated mockup conducted at 50 °C for 2.5 years. Post-mortem analyses were performed from nanometric to millimetric scales using TEM, STXM, ToF-SIMS and SEM techniques. The glass alteration layer consisted of a crystallized Fe-rich smectite mineral, close to nontronite, supporting a dissolution/reprecipitation controlling mechanism for glass alteration. The mean glass dissolution rate ranged between 1.6 × 10−2 g m−2 d−1 to 3.0 × 10−2 g m−2 d−1, a value only 3–5 times lower than the initial dissolution rate. Thermodynamic calculations highlighted a competition between nontronite and protective gel, explaining why in the present conditions the formation of a protective layer is prevented.

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