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1.
BMC Public Health ; 23(1): 2234, 2023 11 13.
Artículo en Inglés | MEDLINE | ID: mdl-37957686

RESUMEN

BACKGROUND: Incidence of skin cancer has been increasing among U.S. Hispanics, who often are diagnosed with larger lesions and at later stage disease. Behaviors to decrease exposure to ultraviolet radiation can reduce risk of skin cancer. We describe skin cancer prevention behaviors and psychosocial variables among Hispanic participants recruited into a skin cancer prevention trial. METHODS: Self-reported Hispanic participants from eight primary care clinics in Tampa, Florida and Ponce, Puerto Rico were recruited into a randomized controlled prevention trial. Information on demographics, sun-related behaviors, and psychosocial variables were collected before intervention materials were provided. Multivariable regression models were used to compare baseline sun-related behaviors and psychosocial variables across groups defined by geographic location and language preference. RESULTS: Participants reported low levels of intentional outdoor tanning, weekday and weekend sun exposure, and very low levels of indoor tanning. However, only a minority of participants practiced sun-protective behaviors often or always, and about 30% experienced a sunburn in the past year. Participants had low levels of recent worry and concern about skin cancer, modest levels of perceived risk and severity, and high levels of response efficacy and self-efficacy. When comparing across groups defined by geographic location and language preference, English-preferring Tampa residents (hereafter referred to as Tampeños) had the highest proportion who were sunburned (35.9%) and tended toward more risky behavior but also had higher protective behavior than did Spanish-preferring Tampeños or Puerto Ricans. Spanish-preferring Puerto Ricans had higher recent concern about skin cancer, comparative chance of getting skin cancer, and response efficacy compared to either English- or Spanish-preferring Tampeños. Spanish-preferring Tampeños had the highest levels of familism and recent distress about skin cancer. CONCLUSIONS: Our results mirror previous observations of low levels of sun-protective behavior among U.S. Hispanics compelling the need for culturally appropriate and translated awareness campaigns targeted to this population. Because Hispanics in Tampa and Puerto Rico reported modest levels of perceived risk and severity, and high levels of response efficacy and self-efficacy, interventions aiming to improve skin cancer prevention activities that are anchored in Protection Motivation Theory may be particularly effective in this population subgroup.


Asunto(s)
Neoplasias Cutáneas , Quemadura Solar , Humanos , Puerto Rico/epidemiología , Florida/epidemiología , Rayos Ultravioleta , Conductas Relacionadas con la Salud , Neoplasias Cutáneas/prevención & control , Neoplasias Cutáneas/etiología , Quemadura Solar/prevención & control , Hispánicos o Latinos/psicología
2.
Psychol Health Med ; 28(4): 995-1003, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-34579608

RESUMEN

The objective of the study is to determine the personal, behavioral and psychological variables associated with somatization and the number of diseases in each gender from a sample of Mexican general population. They answered a questionnaire of behavioral and psychological variables including somatization and the sum of 16 different diseases and any additional one, finally the body mass index (BMI) was measured. A total of 164 participants (women = 90, men = 74) were included. We observed that women had more somatization and number of diseases than men and that more variables (mainly psychological) were associated with somatization and with the number of diseases in women than in men. Among the variables most negatively correlated in women with both variables were sleep quality (r = -0.525 and r = -0.536, p < 0.001), self-acceptance (r = -0.460 and r = -0.501, p < 0.001), positive relations with others (r = -0.447 and r = -0.441 p < 0.001), environmental mastery (r = -0.414, p < 0.001, for both variables), purpose in life and optimism; while men only showed a low negative correlation between emotion regulation and the number of diseases (r = -0.289, p < 0.05). The positive associated variables in women were anxiety, negative emotions and depression; while men showed a lower correlation between these three variables only with somatization. The somatization and age were positively related to the number of diseases in both genders and the BMI was significantly associated with the number of diseases only in men. In conclusion, women had more somatization and number of diseases than men and also had more relation between psychological variables and the two dependent variables than men, which could in part explains the higher values of somatization and the number of diseases in women, considering that they usually present higher values of psychopathological variables.


Asunto(s)
Ansiedad , Depresión , Humanos , Masculino , Femenino , Ansiedad/epidemiología , Depresión/epidemiología , Depresión/psicología , Trastornos de Ansiedad , Encuestas y Cuestionarios
3.
PLoS Biol ; 14(4): e1002436, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-27088359

RESUMEN

Infected hosts differ in their responses to pathogens; some hosts are resilient and recover their original health, whereas others follow a divergent path and die. To quantitate these differences, we propose mapping the routes infected individuals take through "disease space." We find that when plotting physiological parameters against each other, many pairs have hysteretic relationships that identify the current location of the host and predict the future route of the infection. These maps can readily be constructed from experimental longitudinal data, and we provide two methods to generate the maps from the cross-sectional data that is commonly gathered in field trials. We hypothesize that resilient hosts tend to take small loops through disease space, whereas nonresilient individuals take large loops. We support this hypothesis with experimental data in mice infected with Plasmodium chabaudi, finding that dying mice trace a large arc in red blood cells (RBCs) by reticulocyte space as compared to surviving mice. We find that human malaria patients who are heterozygous for sickle cell hemoglobin occupy a small area of RBCs by reticulocyte space, suggesting this approach can be used to distinguish resilience in human populations. This technique should be broadly useful in describing the in-host dynamics of infections in both model hosts and patients at both population and individual levels.


Asunto(s)
Infecciones/fisiopatología , Animales , Eritrocitos , Humanos , Malaria/sangre , Malaria/fisiopatología , Ratones , Plasmodium chabaudi/patogenicidad
4.
J Infect Dis ; 213(6): 1041-8, 2016 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-26503983

RESUMEN

Approximately 3% of Staphylococcus aureus strains that, according to results of conventional phenotypic methods, are highly susceptible to methicillin-like antibiotics also have polymerase chain reaction (PCR) results positive for mecA. The genetic nature of these mecA-positive methicillin-susceptible S. aureus (MSSA) strains has not been investigated. We report the first clearly defined case of reversion from methicillin susceptibility to methicillin resistance among mecA-positive MSSA within a patient during antibiotic therapy. We describe the mechanism of reversion for this strain and for a second clinical isolate that reverts at a similar frequency. The rates of reversion are of the same order of magnitude as spontaneous resistance to drugs like rifampicin. When mecA is detected by PCR in the clinical laboratory, current guidelines recommend that these strains be reported as resistant. Because combination therapy using both a ß-lactam and a second antibiotic suppressing the small revertant population may be superior to alternatives such as vancomycin, the benefits of distinguishing between mecA-positive MSSA and MRSA in clinical reports should be evaluated.


Asunto(s)
Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Infecciones Estafilocócicas/microbiología , Anciano , Secuencia de Aminoácidos , Antibacterianos/uso terapéutico , Bacteriemia/microbiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Secuencia de Bases , ADN Bacteriano/genética , Mutación del Sistema de Lectura , Regulación Bacteriana de la Expresión Génica , Humanos , Masculino , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/fisiología , Nafcilina/administración & dosificación , Nafcilina/uso terapéutico , Proteínas de Unión a las Penicilinas/genética , Proteínas de Unión a las Penicilinas/metabolismo , Infecciones Relacionadas con Prótesis , Infecciones Estafilocócicas/tratamiento farmacológico , Vancomicina/administración & dosificación , Vancomicina/uso terapéutico
5.
P R Health Sci J ; 42(3): 212-218, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37709678

RESUMEN

OBJECTIVE: Migration of physicians in Puerto Rico makes it difficult to obtain specialized care for Alzheimer's disease and related dementias (ADRD). Primary care physicians (PCPs) can fill this gap, but there is limited information on how their beliefs and behaviors towards ADRD affect early diagnostic practices. Using the Theory of Planned Behavior (TPB), we addressed salient beliefs of PCPs that affect their intention to diagnose ADRD early, defined as "performing the recommended clinical testing to diagnose ADRD within 3 months from the patient's first subjective memory complaint". METHODS: This cross-sectional study included 103 Puerto Rican PCPs, surveyed at CME activities and online. We measured PCPs salient beliefs in terms of attitudes, pressure they feel from others, self-perception of ability to diagnose ADRD early, and intention to perform early diagnosis. Questionnaire measures were psychometrically acceptable. RESULTS: Structural equation modeling (PLS-SEM) analysis showed that, combined, framework constructs explained 35.7% of the variance, reflecting a moderate-to-strong intention of PCPs to diagnose early (R2 = 0.357, p < 0.001). Self-perception of skills was the strongest predictor of intention (ß= 0.378, p < 0.001). Hours in ADRD training and years of experience in medical practice were strongly correlated with the percentage of total diagnoses performed by PCPs. CONCLUSION: Training and years of experience may be key for PCPs to have a positive outlook of their skills for early ADRD diagnosis. Findings could be useful to design interventions to dispel myths about ADRD, reduce stigma, and reduce diagnostic hesitancy toward ADRD among PCPs.


Asunto(s)
Enfermedad de Alzheimer , Médicos de Atención Primaria , Humanos , Enfermedad de Alzheimer/diagnóstico , Puerto Rico , Estudios Transversales , Emociones
6.
Patient Educ Couns ; 117: 107978, 2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-37708699

RESUMEN

OBJECTIVE: To identify predictors of genetic risk recall and examine whether recall influences adoption of skin cancer preventive behaviors among Hispanic individuals. METHODS: Hispanic participants randomized to intervention arms (n = 463) of a precision prevention trial were provided MC1R risk information (average, higher) and asked to recall their risk after 3 and 9 months. Predictors of recall (correct versus did not recall/misremembered) were determined by backwards stepwise logistic regression. Intervention effects on preventive behaviors were estimated within strata of 3-month recall. RESULTS: Age inversely predicted correct recall in both risk groups (average: OR3-months(3)= 0.97, 95%CI:0.94-1.01, OR9-months(9)= 0.96, 95%CI:0.93-0.99; higher: OR3 = 0.98, 95%CI:0.95-1.01, OR9 = 0.98, 95%CI:0.95-1.00). Education positively predicted recall among participants at average risk (OR3 =1.64, 95%CI:1.06-2.63, OR9 =1.73, 95%CI:1.12-2.81). Darker untanned skin color inversely predicted recall among participants at higher risk (OR3 =0.68, 95%CI:0.45-0.99, OR9 =0.74, 95%CI:0.50-1.09). Intervention effects for routine sunscreen use and undergoing a clinical skin exam were stronger among participants at higher risk who correctly recalled at 3 months than those who did not recall/misremembered. CONCLUSIONS: Younger age, higher education, and lighter untanned skin color predicted correct recall. Better recall may improve skin cancer prevention outcomes. PRACTICE IMPLICATIONS: Additional strategies are needed to boost recall among Hispanic individuals who are older, less educated, and darker-skinned.


Asunto(s)
Hispánicos o Latinos , Neoplasias Cutáneas , Humanos , Florida , Puerto Rico , Factores de Riesgo , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/prevención & control
7.
Front Public Health ; 11: 1220753, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38274544

RESUMEN

Introduction: Hispanic immigrants are a fast-growing population in the United States of America (USA) that disproportionately suffer from chronic diseases. Despite the increasing prevalence of obesity in Latin-American countries, only a few studies have examined the onset of chronic diseases in Mexican and Central American migrants in Mexico. Objective: The objective of this study is to determine the prevalence of obesity, diabetes, and hypertension in Central American immigrants who are in the process of traveling through northeastern Mexico to the United States. Methods: An observational, descriptive, cross-sectional study was conducted among migrants, mostly Central Americans. Migrants who agreed to participate in the study were interviewed face-to-face by researchers to obtain their sociodemographic data. To obtain the prevalence, many health indicators related to obesity, diabetes, and hypertension, including weight, height, fasting glucose, and blood pressure, were measured. Results: In total, 520 migrants were interviewed; sociodemographic data indicated that most participants were men (76%), from Honduras (72.6%), single (61.2%), and have elementary level of education (48.6%). The somatometric evaluation revealed that 28.9% were diagnosed as overweight, 10.7% with obesity, and 3.3% with malnutrition. Of less prevalence, 8.8% were detected with hypertension and 4.6% had fasting hyperglycemia. The mean participant age was 29.11 ± 10.00 years. For each participant, the average weight was 66.72 ± 13.09 kg; the average height was 1.64 ± 0.08 m; the average body mass index (BMI) was 24.59 ± 4.32; the mean systolic and diastolic pressures were 116.26 ± 15.13 and 74 ± 9.65, respectively; and the average glycemia was 100.97 ± 21.99. El Salvador showed the highest proportion of people with diabetes (14.7%). Women who participated in this study had a higher proportion of obesity (23.4%, p = 0.02) and overweight (36.2%) than men (8.4 and 29.2%, respectively). People from Mexico, Nicaragua, and Honduras reported a high prevalence of overweight participants (63.6, 47.4, and 30.7%, respectively), while people from El Salvador and Nicaragua had a high prevalence of obese participants (23.5 and 21.1%, respectively). Conclusion: We found significant differences in the rates of obesity, diabetes, and hypertension between groups of Central American migrants and their place of origin, age, educational level, and gender. Our findings highlight the importance of exploring differences within groups of Central American migrants traveling through northeastern Mexico to the United States, which may explain several health indicators.


Asunto(s)
Diabetes Mellitus , Emigrantes e Inmigrantes , Hipertensión , Masculino , Humanos , Femenino , Estados Unidos , Adulto Joven , Adulto , México/epidemiología , Sobrepeso/epidemiología , Estudios Transversales , Prevalencia , Factores de Riesgo , Obesidad/epidemiología , Diabetes Mellitus/epidemiología , Hipertensión/epidemiología , Enfermedad Crónica
8.
Patient Educ Couns ; 112: 107742, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37028174

RESUMEN

OBJECTIVE: Examine retention and evaluation of incorporating melanocortin-1 receptor genetic risk information materials in a skin cancer prevention intervention conducted in Hispanics living near Tampa, Florida and Ponce, Puerto Rico. METHODS: Two researchers applied thematic content analysis to identify major themes of open-ended responses (n = 1689) from 489 participants. RESULTS: Five major thematic categories emerged: 1) intervention comments; 2) tips and tricks; 3) cancer prevention; 4) general information; and 5) risk factors and genetics. Responses captured under intervention comments (e.g., information was clear, easy to understand) and tips and tricks for sun protection (e.g., using sunscreen, wearing protective clothing) were most frequent. Participants noted the importance of conducting skin exams professionally or at home. English-preferring Tampa residents stated their individual risk factors, especially race and/or ethnicity, more frequently than Ponce residents and Spanish-preferring Tampa residents. Ponce residents were more likely to comment on wanting to share intervention materials with family and friends. CONCLUSION: Findings suggest Hispanic participants implemented sun safety activities.


Asunto(s)
Neoplasias Cutáneas , Protectores Solares , Humanos , Conductas Relacionadas con la Salud , Hispánicos o Latinos , Factores de Riesgo , Neoplasias Cutáneas/prevención & control , Protectores Solares/uso terapéutico
9.
PEC Innov ; 3: 100232, 2023 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-38028436

RESUMEN

Objective: To explore factors associated with communication and information-seeking after receipt of skin cancer prevention information among Hispanic individuals. Methods: Multivariable logistic regression was used to analyze existing data on demographics, personal experience, salience, and beliefs variables collected from Hispanic individuals to determine independent associations with sharing and seeking information about skin cancer prevention. Results: Of 578 participants, 53% reported any communication about skin cancer prevention behaviors or skin cancer genetic risk; and 31% and 21% sought additional information about preventive behaviors or genetic risk, respectively. Female sex, greater perceived severity, higher comparative chance of getting skin cancer, and lower health literacy were associated with greater communication, while having no idea of one's own skin cancer risk was related to less communication. Greater health numeracy and higher cancer worry were associated with information-seeking about prevention behaviors and genetic risk. Conclusion: Up to half of participants reported communication or information-seeking, although factors associated with specific activities differed. Future studies should evaluate how to promote communication behaviors in the Hispanic community and how sharing and seeking information influence an individual's network prevention practices. Innovation: Several factors related to communication behaviors among Hispanic people after obtaining skin cancer prevention information were identified.Trial registration: This trial was registered on clinicaltrials.gov (NCT03509467).

10.
J Clin Microbiol ; 50(3): 1099-101, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22170938

RESUMEN

Metastatic infection is an infrequent complication of non-Staphylococcus aureus staphylococcal infection. Here we report a case of bloodstream infection due to Staphylococcus intermedius. To our knowledge, ours is the only known case of metastatic infection with S. intermedius.


Asunto(s)
Bacteriemia/complicaciones , Bacteriemia/diagnóstico , Infecciones Estafilocócicas/diagnóstico , Infecciones Estafilocócicas/patología , Staphylococcus intermedius/aislamiento & purificación , Anciano , Bacteriemia/microbiología , Bacteriemia/patología , Humanos , Masculino , Infecciones Estafilocócicas/microbiología
11.
Patient Educ Couns ; 105(10): 3143-3150, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-35778318

RESUMEN

OBJECTIVE: To assess Hispanic participants' ratings of intervention materials and examine differences by language preference. METHODS: Participants on a skin cancer prevention trial were randomized to receive generic (n = 457) or precision prevention materials conveying average (n = 195) or higher genetic risk (n = 268) based on MC1R genotype. Three months after receiving either English or Spanish language prevention materials, participants reported amount read, believability and clarity of materials, and intention to change preventive behavior. RESULTS: Participants reported high levels on all four outcomes, but the precision prevention groups noted lower clarity than the generic group (p = 3.2 ×10-6). Participants preferring Spanish provided consistently higher scores than those preferring English. Among English-preferring participants, those in the precision prevention groups scored lower on all measures than those in the generic group. CONCLUSIONS: Skin cancer prevention materials were well-received by Hispanic participants. Higher scores among participants preferring Spanish may indicate acquiescence bias, or that translated prevention materials met their linguistic needs. Participants in the precision prevention groups with English language preference may have challenges in the uptake of genetic risk results. PRACTICE IMPLICATIONS: Availability of Spanish materials may have facilitated higher scores. Additional strategies should be explored to optimize participants' believability and clarity of precision prevention materials.


Asunto(s)
Hispánicos o Latinos , Neoplasias Cutáneas , Florida , Humanos , Lenguaje , Puerto Rico , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/prevención & control
12.
Cancer Res Commun ; 2(1): 28-38, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-35845857

RESUMEN

Purpose: Skin cancer incidence is increasing among Hispanics, who experience worse outcomes than non-Hispanic Whites. Precision prevention incorporating genetic testing for MC1R, a skin cancer susceptibility marker, may improve prevention behavior. Patients and Methods: Hispanic participants (n=920) from Tampa, FL and Ponce, PR, were block-randomized within MC1R higher- and average-risk groups to precision prevention or generic prevention arms. We collected baseline information on demographics, family history of cancer, phenotypic characteristics, health literacy, health numeracy, and psychosocial measures. Participants reported weekday and weekend sun exposure (in hours), number of sunburns, frequency of five sun protection behaviors, intentional outdoor and indoor tanning, and skin examinations at baseline, three months, and nine months. Participants also reported these outcomes for their eldest child ≤10 years old. Results: Among MC1R higher-risk participants, precision prevention increased sunscreen use (OR=1.74, p=0.03) and receipt of a clinical skin exam (OR=6.51, p=0.0006); and it decreased weekday sun exposure hours (ß=-0.94, p=0.005) and improved sun protection behaviors (ß=0.93, p=0.02) in their children. There were no significant intervention effects among MC1R average risk participants. The intervention did not elevate participant cancer worry. We also identified moderators of the intervention effect among both average- and higher-risk participants. Conclusions: Receipt of MC1R precision prevention materials improved some skin cancer prevention behaviors among higher-risk participants and their children and did not result in reduced prevention activities among average-risk participants. Despite these encouraging findings, levels of sun protection behaviors remained suboptimal among participants, warranting more awareness and prevention campaigns targeted to Hispanics.


Asunto(s)
Neoplasias Cutáneas , Quemadura Solar , Niño , Humanos , Conductas Relacionadas con la Salud , Neoplasias Cutáneas/genética , Quemadura Solar/prevención & control , Protectores Solares/uso terapéutico , Factores de Riesgo
13.
Pharmaceuticals (Basel) ; 14(10)2021 Oct 12.
Artículo en Inglés | MEDLINE | ID: mdl-34681257

RESUMEN

The higher molecular weight and low solubility of amphotericin B (AmB) hinders its topical administration. The aim of this study was to incorporate Bursera graveolens essential oil into an AmB topical gel (AmB + BGEO gel) in order to promote the diffusion of the drug through the skin in the treatment of cutaneous candidiasis. AmB + BGEO gel formulation was determined using a factorial experiment. Physical and chemical parameters, stability, in vitro release profile and ex vivo permeation in human skin were evaluated. In vitro antimicrobial activity was studied using strains of C. albicans, C. glabrata and C. parapsilosis. The tolerability was evaluated using in vitro and in vivo models. AmB + BGEO gel presented appropriate characteristics for topical administration, including pH of 5.85, pseudoplastic behavior, optimal extensibility, as well as high stability and acceptable tolerability. In vitro release studies showed that the formulation releases the drug following a Boltzmann sigmoidal model. Finally, AmB + BGEO gel exhibited higher amount of drug retained inside the skin and lower Minimum Inhibitory Concentration than a formulation sans essential oil. Therefore, these results suggest that the incorporation of B. graveolens essential oil in the formulation could be used as strategy to promote a local effect in the treatment of cutaneous candidiasis.

15.
J Neuropathol Exp Neurol ; 68(9): 985-93, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19680144

RESUMEN

The use of dichloroacetate (DCA) for treating patients with mitochondrial diseases is limited by the induction of peripheral neuropathy. The mechanisms of DCA-induced neuropathy are not known. Oral DCA treatment (50-500 mg/kg per day for up to 16 weeks) induced tactile allodynia in both juvenile and adult rats; concurrent thermal hypoalgesia developed at higher doses. Both juvenile and adult rats treated with DCA developed nerve conduction slowing that was more pronounced in adult rats. No overt axonal or glial cell abnormalities were identified in peripheral nerves or spinal cord of any DCA-treated rat, but morphometric analysis identified a reduction of mean axonal caliber of peripheral nerve myelinated fibers. Dichloroacetate treatment also caused accumulation of oxidative stress markers in the nerves. These data indicate that behavioral, functional, and structural indices of peripheral neuropathy may be induced in both juvenile and adult rats treated with DCA at doses similar to those in clinical use. Dichloroacetate-induced peripheral neuropathy primarily afflicts axons and involves both metabolic and structural disorders. The DCA-treated rat may provide insight into the pathogenesis of this peripheral neuropathy and facilitate development of adjuvant therapeutics to prevent this disorder that currently restricts the clinical use of DCA.


Asunto(s)
Ácido Dicloroacético/toxicidad , Hipoestesia/inducido químicamente , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Enfermedades del Sistema Nervioso Periférico/patología , Factores de Edad , Animales , Ácido Dicloroacético/administración & dosificación , Relación Dosis-Respuesta a Droga , Electromiografía , Femenino , Pie/inervación , Hipoestesia/patología , Hipoestesia/fisiopatología , Conducción Nerviosa/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Enfermedades del Sistema Nervioso Periférico/fisiopatología , Ratas , Ratas Sprague-Dawley , Piel/inervación
17.
ACS Omega ; 3(8): 10243-10249, 2018 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-31459153

RESUMEN

Our work reports the hydrothermal synthesis of a bimetallic composite CoMoS, followed by the addition of cellulose fibers and its subsequent carbonization under Ar atmosphere (CoMoS@C). For comparison, CoMoS was heat-treated under the same conditions and referred as bare-CoMoS. X-ray diffraction analysis indicates that CoMoS@C composite matches with the CoMoS4 phase with additional peaks corresponding to MoO3 and CoMoO4 phases, which probably arise from air exposure during the carbonization process. Scanning electron microscopy images of CoMoS@C exhibit how the CoMoS material is anchored to the surface of carbonized cellulose fibers. As anode material, CoMoS@C shows a superior performance than bare-CoMoS. The CoMoS@C composite presents an initial high discharge capacity of ∼1164 mA h/g and retains a high specific discharge capacity of ∼715 mA h/g after 200 cycles at a current density of 500 mA/g compared to that of bare-CoMoS of 102 mA h/g. The high specific capacity and good cycling stability could be attributed to the synergistic effects of CoMoS and carbonized cellulose fibers. The use of biomass in the anode material represents a very easy and cost-effective way to improve the electrochemical Li-ion battery performance.

18.
J Inorg Biochem ; 101(11-12): 1958-73, 2007 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-17761292

RESUMEN

Maya Blue is an ancient blue pigment composed of palygorskite clay and indigo. It was used by the ancient Maya and provides a dramatic background for some of the most impressive murals throughout Mesoamerica. Despite exposure to acids, alkalis, and chemical solvents, the color of the Maya Blue pigment remains unaltered. The chemical interaction between palygorskite and indigo form an organic/inorganic complex with the carbonyl oxygen of the indigo bound to a surface Al(3+) in the Si-O lattice. In addition indigo will undergo an oxidation to dehydroindigo during preparation. The dehydro-indigo molecule forms a similar but stronger complex with the Al(3+). Thus, Maya Blue varies in color due to the mixed indigo/dehydroindigo complex. The above conclusions are the result of application of multiple techniques (X-ray diffraction, differential thermal analysis/thermal gravimetric analysis, high resolution transmission electron microscopy, scanning electron microscopy, infrared and Raman spectroscopy) to the characterization of the organic/inorganic complex. A picture of the bonding of the organic molecule to the palygorskite surface forming a surface complex is developed and supported by the results of density functional theory calculations. We also report that other organic molecules such as thioindigo form similar organic/inorganic complexes thus, opening an entirely new class of complex materials for future applications.


Asunto(s)
Colorantes/química , Indoles/química , Carmin de Índigo/análogos & derivados , Carmin de Índigo/química , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Estructura Molecular , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría Raman , Difracción de Rayos X
19.
Ultramicroscopy ; 127: 64-9, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22925737

RESUMEN

Hydrotreatment catalytic operations are commonly performed industrially by layered molybdenum sulfide promoted by cobalt or nickel in order to remove heteroelements (S, N, O) from fossil fuels and biofuels. Indeed, these heteroelements are responsible of the emission of pollutants when these fuels are used in vehicles. In this respect, previous studies made by our research group have shown that the active phase under steady state conditions is partially carbided while strong bending effects of MoS2 slabs were also observed. However, up to now, the morphology of the resulting Co/MoSxCy carbided catalyst has not been fully characterized. In the present study, for the first time, a chemical reaction between the carbon content of a TEM Cu/C grid and a freshly sulfide Co/MoS2 catalyst was in situ observed at 300 °C and 450 °C by HRTEM experimental techniques at ~10 nm of resolution. Results indicate that bending of MoS2 layers occurred due to carbon addition on MoS2 edge sites, as observed in stabilized catalysts after HDS reaction. Using a silicon grid, only cracks of MoS2 slabs were observed without bending effect confirming the role of structural-carbon in this change of morphology.

20.
Materials (Basel) ; 6(1): 198-205, 2013 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-28809302

RESUMEN

The chemical synthesis of gold nanoparticles (NP) by using gold (III) chloride trihydrate (HAuCl∙3H2O) and sodium citrate as a reducing agent in aqueous conditions at 100 °C is presented here. Gold nanoparticles areformed by a galvanic replacement mechanism as described by Lee and Messiel. Morphology of gold-NP was analyzed by way of high-resolution transmission electron microscopy; results indicate a six-fold icosahedral symmetry with an average size distribution of 22 nm. In order to understand the mechanical behaviors, like hardness and elastic moduli, gold-NP were subjected to nanoindentation measurements-obtaining a hardness value of 1.72 GPa and elastic modulus of 100 GPa in a 3-5 nm of displacement at the nanoparticle's surface.

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