Corrosion Inhibition in CO2-Saturated Brine by Nd3+ Ions.

This study reports the use of an inorganic corrosion inhibitor to mitigate dissolved CO2-induced corrosion. Using electrochemical techniques (polarization curves, open circuit potential, polarization resistance, and electrochemical impedance), the effect of adding Nd3+ ions on the corrosion resistance of X52 steel immersed in CO2-saturated brine at 20 °C and 60 °C was evaluated. The polarization curves showed that the Icorr values tend to decrease with increasing Nd3+ ion concentration, up to the optimal inhibition concentration, and that the corrosion potential increases at nobler values. Open circuit potential measurements showed a large increase in potential values immediately after the addition of the Nd3+ ions. Similarly, polarization resistance measurements showed similar trends. It was observed that regardless of temperature, Nd3+ ions can reduce the corrosion rate by more than 97% at doses as low as 0.001 M. Electrochemical impedance measurements confirmed the formation of a protective layer on the steel surface, which caused an increase in the magnitude of the impedance module and phase angle, which indicates an increase in the resistance to charge transfer and capacitive properties of the metallic surface. The characterization of the metallic surface showed that the protective layer was formed by Nd carbonates, whose formation was due to a CO2 capture process.

Behavior of Ni20Cr Alloy in Molten Nitrate Salts.

This study reports the behavior of the Ni20Cr alloy in molten nitrate salts. Its behavior was evaluated in the eutectic mixture called Solar Salt (binary salt) and in a ternary mixture (90% Solar Salt and 10% lanthanum nitrate). The addition of lanthanum nitrate was performed to determine if the presence of the La3+ cation could act as a corrosion inhibitor. Through mass loss and potentiodynamic polarization studies, the effects of both electrolytes on the corrosion resistance of the alloy at 300, 400, and 500 °C and at exposure times of 250, 500, 750, and 1000 h were determined. The results showed an increase in the corrosivity of the ternary salt, due to a decrease in its melting point and an increase in the concentration of nitrate ions. However, it was observed that the La3+ cations formed a protective layer (La2O3) on the alloy surface. In both corrosive media, the Ni20Cr alloy showed excellent corrosion resistance, due to its ability to form protective layers of Cr2O3, NiO, and NiCr2O4, in addition to the presence of a layer of La2O3 in the case of the ternary salt.

Corrosion Behavior of Al Modified with Zn in Chloride Solution.

Aluminum-based alloys have been considered candidate materials for cathodic protection anodes. However, the Al-based alloys can form a layer of alumina, which is a drawback in a sacrificial anode. The anodes must exhibit uniform corrosion to achieve better performance. Aluminum can be alloyed with Zn to improve their performance. In this sense, in the present research, the electrochemical corrosion performance of Al-xZn alloys (x = 1.5, 3.5, and 5 at.% Zn) exposed to 3.5 wt.% NaCl for 24 h was evaluated. Polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) were used to identify the electrochemical behavior. The microstructure of the samples before the corrosion assessment was characterized by means of X-ray diffraction analyses (XRD) and scanning electron microscopy (SEM). In addition, microstructures of the corroded surfaces were characterized using X-ray mappings via SEM. Polarization curves indicated that Zn additions changed the pseudo-passivation behavior from what pure Al exhibited in a uniform dissolution regime. Furthermore, the addition of Zn shifted the corrosion potential to the active side and increased the corrosion rate. This behavior was consistent with the proportional decrease in polarization resistance (Rp) and charge transfer resistance (Rct) in the EIS. The analysis of EIS was done using a mathematical model related to an adsorption electrochemical mechanism. The adsorption of chloride at the Al-Zn alloy surface formed aluminum chloride intermediates, which controlled the rate of the process. The rate constants of the reactions of a proposed chemical mechanism were evaluated.

The Emergence of Hepatitis C Virus Genotype 4d Among Human Immunodeficiency Virus-Infected Patients in Mexico City: A Molecular Epidemiological Study.

ABSTRACT: The recent detection of hepatitis C virus genotype 4 infection in human immunodeficiency virus-infected patients prompted performing molecular characterization of these isolates. All the Mexican isolates belonged to a subcluster within the 4d group and shared a common ancestor with a French isolate. The estimated timing of introduction in Mexico City was as recent as December 2015.

Baseline Hepatitis C Virus NS5A Resistance-Associated Polymorphisms in Patients With and Without Human Immunodeficiency Virus Coinfection in Mexico.

Objective: We aimed to evaluate the frequency and associated factors of baseline NS5A resistance-associated substitutions (RASs) in patients coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) monoinfection with genotype 1b (GT1b) or genotype 1a (GT1a). Moreover, we performed a phylogenetic analysis to evaluate the pattern of clustering among samples of patients with RASs. Results: Fifty-five patients were infected with GT1a, of whom 44 (80%) were HIV-infected patients. RAS prevalence in GT1a was 14% (6/44) and distributed as follows: 5 (11%) harbored M28V and 1 (2%) A92T. Twenty-four patients were infected with HCV GT1b, of whom only 5 (21%) were HIV coinfected; RASs were found in 17/24 (71%) patients, as follows: Y93H+F37L+Q54H (1/24), Y93H+F37L (1/24), P58S (1/24), L31F+F37L (1/24), F37L+H/Q54H (3/24), and F37L (10/24). Only GT1b was significantly associated with RASs (adjusted odds ratio 16.37; 95% confidence interval 2.74-97.48; p = 0.002) in the multivariate analysis. A cluster of sequences from HIV/HCV GT1a patients was found; however, we did not find phylogenetic relationships among sequences with NS5A RASs. Conclusions: In our population of HCV-infected patients, the frequency of NS5A RASs at baseline was somewhat similar to the previously reported worldwide rate. HCV GT1b showed the most significant association with harboring of NS5A RASs. Of note, despite there being clusters among sequences of HIV-coinfected patients, NS5A RASs were not transmitted.

Persistent high levels of immune activation and their correlation with the HIV-1 proviral DNA and 2-LTR circles loads, in a cohort of Mexican individuals following long-term and fully suppressive treatment.

OBJECTIVES: The aim of this study was to investigate the correlation between the HIV-1 reservoir and the levels of immune activation in chronic patients under fully suppressive cART. METHODS: We quantified the HIV proviral DNA and 2-LTR circles loads from PBMCs, the levels of CD38+ and Ki-67+ T-cells, and the levels of IL-7 in a cohort of patients with more than 5 years of ART at enrollment and after 1 year. RESULTS: In 29 participants with a median of 8 years (IQR, 6.9-9.4) under suppressive cART we found higher levels of CD8+ CD38+ T-cells after 1-year (P = .000). There was a non-statistically significant poor correlation between the levels of immune activation and the proviral DNA of CD4+ and CD8+ T-cells. Ki-67+ T-cells declined without significant differences, and there was no significant correlation with the proportion of CD38+. IL-7 decreased at the follow-up observation (P = .094), but there was no correlation with the levels of CD38+ and Ki-67+ T-cells. CONCLUSIONS: We found a weak but non-statistically significant correlation of the levels of T-cell activation with the proviral DNA and 2-LTR circles. This suggests the likely occurrence of further mechanisms driving chronic versus early immune activation other than viral replication by itself in chronic patients.

Electrochemical Performance of Fe40Al-X (X = Cr, Ti, Co, Ni) Alloys Exposed to Artificial Saliva.

Fe-Al intermetallic compounds have been considered excellent candidates as alternative alloys for various applications in corrosive environments compared to other Fe-based alloys. Their excellent corrosion resistance is due to the development of an Al-based passive layer. The performance of the passive layer can be improved by adding a third alloy element. Therefore, in this study the electrochemical performance of the Fe40Al intermetallic alloy modified by the addition of a third alloy element (Cr, Ti, Co, Ni) is evaluated. The corrosion resistance of intermetallic alloys has been evaluated by electrochemical tests (potentiodynamic polarization curves, and measurements of open circuit potential, linear polarization and electrochemical impedance) in artificial saliva. The performance of intermetallic alloys was compared with that of Ti. The results obtained showed that the addition of Ni and Ti substantially improves the corrosion resistance of the base intermetallic. The corrosion resistance shown is comparable or greater than that shown by Ti. However, the addition of Co reduces the corrosion resistance of the base intermetallic.

HIV-1 acquired drug resistance to integrase inhibitors in a cohort of antiretroviral therapy multi-experienced Mexican patients failing to raltegravir: a cross-sectional study.

BACKGROUND: In resource-limited settings, multi-experienced HIV infected patients are often prescribed raltegravir for salvage therapy. Patients failing raltegravir-containing regimens require other drugs including other integrase inhibitors. In this context, real-life data about the resistance and cross-resistance pathways between integrase inhibitors is limited. The aim of this study was to investigate integrase resistance pathways in a cohort of Mexican multi-experienced patients failing of a raltegravir-containing salvage regimen. METHODS: Twenty-five plasma samples from subjects failing antiretroviral regimens which included raltegravir were obtained from various healthcare centres from 2009 to 2017 in Mexico. Antiretroviral history and demographics were collected. Samples were processed for integrase resistance genotyping testing by sequencing. The viral sequences were analysed with the Stanford HIV drug resistance database algorithm. Data was analysed with SPSS Statistics software. RESULTS: We found a mean viral load of 4.17 log10 c/mL (SD 1.11) at the time of virologic failure. Forty-eight percent of the samples were raltegravir resistant. The Y143R/H/C substitutions were the most prevalent, followed by the N155H, and both Q148H/K and G140S/A in the same proportion. The Q148 + G140 combination was found in (12%) of the samples. Cross-resistance to elvitegravir was found in 83.3% and in 18.2% for both dolutegravir and bictegravir. Thirteen samples (52%) were susceptible to the four integrase strand-transfer inhibitors. CONCLUSIONS: Our findings suggest a high occurrence of resistance and cross-resistance to other integrase inhibitors among multi-experienced subjects failing raltegravir. We found a modestly lower proportion of cross-resistance to dolutegravir than data from clinical trials. Likely this drug could be used for salvage therapy. Explanations for the absence of mutations in half of the samples, other than reduced adherence, should be further investigated. Close surveillance is needed.

Encefalopatía Posterior Reversible asociada a Exacerbación de Enfermedad Pulmonar Obstructiva Crónica / Reversible Posterior Encephalopathy associated with Exacerbation of Chronic Obstructive Pulmonary Disease

Resumen El Síndrome de Encefalopatía Reversible Posterior (PRES) es una entidad clínica y radiológica reversible. Existen varias entidades clínicas que se asocian con PRES. La enfermedad pulmonar obstructiva crónica (EPOC) es un factor predisponente poco frecuente para el desarrollo de esta patología. Se presenta el caso de una mujer de 71 años de edad que estaba siendo tratada por una exacerbación aguda de EPOC y desarrolló alteración del sensorio y crisis convulsivas. Los hallazgos de imágenes características, los síntomas clínicos asociados y su historial médico llevaron a un diagnóstico de PRES en nuestro paciente. A pesar de que la asociación de PRES y EPOC es una entidad poco común, el diagnóstico de PRES debe ser un diferencial en caso de que un paciente desarrolle encefalopatía o convulsiones en la exacerbación de EPOC.

Abstract Posterior Reversible Encephalopathy Syndrome (PRES) is a reversible clinical and radiological entity. There are several entities that are associated with PRES. Chronic obstructive pulmonary disease (COPD) is a rare factor for the development of this condition. We present the case of a 71-years-old woman who was being treated for an acute exacerbation of COPD and developed sensory impairment and seizures. The findings of characteristic images, associated clinical symptoms and their medical history led to a diagnosis of PRES in our patient. Although the association of PRES and COPD is a rare entity, the diagnosis of PRES should be a differential if a patient develops encephalopathy or seizures in the exacerbation of COPD.

El Perfil Epidemiológico Y Clínico De La Esclerosis Múltiple En El Ecuador / The Clinical And Epidemiological Profile Of Multiple Sclerosis In Ecuador

Resumen En el Ecuador ha habido un importante incremento en el número de publicaciones sobre Esclerosis Múltiple (EM) en los últimos años. Este interés por conocer el comportamiento clínico y epidemiológico de la enfermedad nos ha permitido establecer semejanzas y diferencias con otras cohortes de pacientes con EM que provienen de regiones en donde la prevalencia de la enfermedad es alta. El Ecuador sigue siendo un país de baja prevalencia, los estudios han demostrado que la misma fluctúa entre 3 a 5 casos por 100.000 habitantes. El comportamiento epidemiológico es muy similar a la de cohortes europeas por ejemplo el sexo femenino es el principalmente afectado. Sin embargo, el comportamiento clínico difiere en lo que respecta a deterioro cognitivo, fatiga siendo éstos menos frecuentes. Aún se desconoce el impacto de la vitamina D en nuestros pacientes debido a que, solo un estudio ha sido llevado a cabo. Al parecer, existe una alta prevalencia de deficiencia e insuficiencia de vitamina D en los pacientes ecuatorianos pero no se traduce en un incremento de prevalencia o discapacidad como ocurre en poblaciones europeas. A pesar de que tenemos una mejor comprensión de la enfermedad en el país, más estudios son necesarios y es imperativo incluir a todos los pacientes ecuatorianos con esclerosis múltiple con el fin de mejorar nuestro conocimiento sobre el comportamiento de esta patología en nuestra región.

Abstract In recent years, the number of publications on Multiple Sclerosis (MS) from Ecuador has seen a significant increase. As a result, the research on the clinical and epidemiological behaviour of the disease has allowed us to make comparisons with other cohorts of patients with MS that come from regions where the prevalence of the disease is high. Nevertheless, Ecuador is still a country in which the prevalence of MS is low with a prevalence that fluctuates between 3 to 5 cases per 100,000 inhabitants. The epidemiological behaviour of MS is very similar to that of european cohorts, for example female patients are the most affected. However, the clinical behaviour of multiple sclerosis differs in terms of cognitive impairment and fatigue being less frequent. The impact of vitamin D on patients with MS is still unknown as only one study has been carried out. This study show that there is a high prevalence of vitamin D deficiency and insufficiency in ecuadorian patients, but this does not translate into an increase in prevalence or disability as it does in european populations. Although we have a better understanding of the disease in the country, more studies are necessary, and it is imperative that all ecuadorian patients with MS be included in future studies in order to improve our knowledge about the behaviour of this disease in our region.

Degradation capacities of bacteria and yeasts isolated from the gut of Dendroctonus rhizophagus (Curculionidae: Scolytinae).

Bark beetles (Curculionidae: Scolytinae) feed on the xylem and phloem of their host, which are composed of structural carbohydrates and organic compounds that are not easily degraded by the insects. Some of these compounds might be hydrolyzed by digestive enzymes produced by microbes present in the gut of these insects. In this study, we evaluated the enzymatic capacity of bacteria (Acinetobacter lwoffii, Arthrobacter sp., Pseudomonas putida, Pseudomonas azotoformans, and Rahnella sp.) and yeasts (Candida piceae, Candida oregonensis, Cyberlindnera americana, Zygoascus sp., and Rhodotorula mucilaginosa) isolated from the Dendroctonus rhizophagus gut to hydrolyze cellulose, xylan, pectin, starch, lipids, and esters. All isolates, with the exception of C. piceae, showed lipolytic activity. Furthermore, P. putida, P. azotoformans, C. americana, C. piceae, and R. mucilaginosa presented amylolytic activity. Esterase activity was shown by A. lwoffii, P. azotoformans, and Rahnella sp. Cellulolytic and xylanolytic activities were present only in Arthrobacter sp. and P. azotoformans. The pectinolytic activity was not recorded in any isolate. This is the first study to provide evidence on the capacity of microbes associated with the D. rhizophagus gut to hydrolyze specific substrates, which might cover part of the nutritional requirements for the development, fitness, and survival of these insects.

Transmitted HIV drug resistance among drug-naive subjects recently infected with HIV in Mexico City: a World Health Organization survey to classify resistance and to field test two alternative patient enrollment methods.

In 2004, the World Health Organization performed a survey to assess transmitted drug resistance in Mexico City among drug-naive persons with newly diagnosed human immunodeficiency virus (HIV) infection and likely to be recently infected who were attending 3 voluntary counseling and testing sites. A parallel study comparing 2 alternative methods of enrolling survey participant was conducted in 9 voluntary counseling and testing sites in central Mexico. In study arm 1, subject information, consent and blood specimens were obtained during the HIV diagnostic testing visit. In study arm 2, consent and blood specimens were obtained at the return visit, only from those who were HIV infected. This survey classified nonnucleoside reverse-transcriptase inhibitor and nucleoside reverse-transcriptase inhibitor transmitted drug resistance as <5% and 5%-15%, respectively. Arm 2 yielded major advantages in cost and workload, with no evidence of increased sampling bias.

HIV Drug Resistance-Associated Mutations in Antiretroviral Naïve HIV-1-Infected Latin American Children.

Our goal was to describe the presence of HIV drug resistance among HIV-1-infected, antiretroviral (ARV) naïve children and adolescents in Latin America and to examine resistance in these children in relation to drug exposure in the mother. Genotyping was performed on plasma samples obtained at baseline from HIV-1-infected participants in a prospective cohort study in Brazil, Argentina, and Mexico (NISDI Pediatric Study). Of 713 HIV-infected children enrolled, 69 were ARV naïve and eligible for the analysis. At enrollment, mean age was 7.3 years; 81.2% were infected with HIV perinatally. Drug resistance mutations (DRMs) were detected in 6 (8.7%; 95% confidence interval 3.1-18.2%) ARV-naïve subjects; none of the mothers of these 6 received ARVs during their pregnancies and none of the children received ARV prophylaxis. Reverse transcriptase mutations K70R and K70E were detected in 3 and 2 subjects, respectively; protease mutation I50 V was detected in 1 subject. Three of the 6 children with DRMs initiated ARV therapy during followup, with a good response in 2. The overall rate of primary drug resistance in this pediatric HIV-infected population was low, and no subjects had more than 1 DRM. Mutations associated with resistance to nucleoside reverse transcriptase inhibitors were the most prevalent.

Antiretroviral resistance among HIV type 1-infected women first exposed to antiretrovirals during pregnancy: plasma versus PBMCs.

Resistance-associated mutations (RAMs) in plasma samples from HIV-1-infected women who received antiretroviral (ARV) prophylaxis during pregnancy was assessed and correlated with the detection of RAMs in peripheral blood mononuclear cells (PMBCs). The study population was composed of HIV-1-infected women enrolled in a prospective cohort study in Latin America and the Caribbean (NISDI Perinatal Study) as of March 1, 2005, who were diagnosed with HIV-1 infection during the current pregnancy, who received ARVs during pregnancy for prevention of mother-to-child transmission of HIV-1, and who were followed through at least the 6-12 week postpartum visit. Plasma samples collected at enrollment during pregnancy and at 6-12 weeks postpartum were assayed for RAMs. Plasma results were compared to previously described PBMC results from the same study population. Of 819 enrolled subjects, 197 met the eligibility criteria. Nucleic acid amplification was accomplished in 123 plasma samples at enrollment or 6-12 weeks postpartum, and RAMs were detected in 22 (17.9%; 95%CI: 11.7-25.9%). Previous analyses had demonstrated detection of RAMs in PBMCs in 19 (16.1%). There was high concordance between RAMs detected in plasma and PBMC samples, with only eight discordant pairs. The prevalence of RAMs among these pregnant, HIV-1-infected women is high (15%). Rates of detection of RAMs in plasma and PBMC samples were similar.

Early HCV RNA changes in patients with chronic hepatitis C treated with peginterferon alfa 2b and ribavirin.

INTRODUCTION: Currently, interferon alfa and ribavirin are the mainstay of therapy for patients with chronic hepatitis C. Recently the pegylation of interferon has allowed a once weekly application, resulting in an increased sustained viral response rate. The analysis of serum HCV dynamics has been shown to be useful in predicting clinical effects and optimizing the treatment regimen. AIM: The aim of the present study was to assess early serum HCV RNA changes in patients with chronic hepatitis C treated with peginterferon alfa 2b plus ribavirin. METHODS: Male and female patients aged 18 to 65 years with chronic hepatitis C were eligible for the study. All patients received peginterferon alfa 2b 1.5 micrograms/kg once-weekly for 4 weeks and then peginterferon alfa 2b 0.5 microgram/kg once-weekly until the completion of the 48 week trial period, plus ribavirin orally with meals, adjusted to body weight. HCV RNA was determined at base-line, 48 hours, 4 and 12 weeks of therapy. RESULTS: Data were obtained from 20 patients with chronic hepatitis C treated with peginterferon alfa 2b and ribavirin; 16 male, 4 female, with a mean age of 44.4 +/- 11.9 years, 16 patients (80%) were infected with HCV genotype 1, the remainder were infected with genotype 2. Mean baseline HCV RNA for the total group was 1,091,405 +/- 972,715 IU/mL. Mean reductions in viral load at 48 hours, 4 and 12 weeks for the 20 patients were 1.31 +/- 0.91 log, 1.99 +/- 1.27 log and 2.31 +/- 1.25 log, respectively. A > 2 log reduction in HCV RNA was noticed in 12/20 patients (60%) at 4 weeks (early viral responders), in 9 of them (45%) HCV RNA was undetectable. This response in HCV RNA persisted at 12 weeks of therapy. Early viral responders had a significant reduction in HCV RNA at 48 hours after the initial peginterferon alfa 2b injection (> 1 log reduction). Early viral response was observed in 8/16 patients with HCV genotype 1, and in all genotype 2 patients. CONCLUSION: Treatment with peginterferon alfa 2b and ribavirin produces significant changes in the early HCV viral dynamics supporting the concept that such changes may be pivotal in achieving a sustained viral response.