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1.
Appl Opt ; 60(23): 6935-6942, 2021 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-34613174

RESUMEN

Hadamard, cosine, and noiselet bases are implemented into a digital holographic microscope based on single-pixel imaging with the capability to retrieve images of complex objects. The object is illuminated with coherent light modulated with different patterns deployed in a digital micromirror device, and the resulting fields are captured by single-pixel detection. For amplitude images, the experimental results of the three bases are evaluated with the peak SNR criteria. It is shown that the cosine basis recovers amplitude distributions with the best quality. Regarding phase images, the recovered ones compare well with those obtained with a CMOS camera.

2.
PLoS Negl Trop Dis ; 15(9): e0009746, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-34570792

RESUMEN

BACKGROUND: Insecticide use continues as the main strategy to control Aedes aegypti, the vector of dengue, Zika, chikungunya, and yellow fever. In the city of Tapachula, Mexico, mosquito control programs switched from pyrethroids to organophosphates for outdoor spatial spraying in 2013. Additionally, the spraying scheme switched from total coverage to focused control, prioritizing areas with higher entomological-virological risk. Five years after this strategy had been implemented, we evaluated the status and variability of insecticide resistance among Ae. aegypti collected at 26 sites in Tapachula. METHODOLOGY/PRINCIPAL FINDINGS: We determined the lethal concentrations at 50% of the tested populations (LC50) using a bottle bioassay, and then, we calculated the resistance ratio (RR) relative to the susceptible New Orleans strain. Permethrin and deltamethrin (pyrethroids), chlorpyrifos and malathion (organophosphates), and bendiocarb (carbamate) were tested. The frequencies of the substitutions V1016I and F1534C, which are in the voltage-gated sodium channel and confer knockdown-resistance (kdr) to pyrethroid insecticides, were calculated. Despite 5 years having passed since the removal of pyrethroids from the control programs, Ae. aegypti remained highly resistant to permethrin and deltamethrin (RR > 10-fold). In addition, following 5 years of chlorpyrifos use, mosquitoes at 15 of 26 sites showed moderate resistance to chlorpyrifos (5- to 10-fold), and the mosquitoes from one site were highly resistant. All sites had low resistance to malathion (< 5-fold). Resistance to bendiocarb was low at 19 sites, moderate at five, and high at two. Frequencies of the V1016I ranged from 0.16-0.71, while C1534 approached fixation at 23 sites (0.8-1). Resistance profiles and kdr allele frequencies varied across Tapachula. The variability was not associated with a spatial pattern at the scale of the sampling. CONCLUSION/SIGNIFICANCE: Mosquito populations respond to selection pressure at a focal scale in the field. Spatial variation across sites highlights the importance of testing multiple sites within geographical regions.

4.
Trop Biomed ; 38(2): 134-142, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-34172702

RESUMEN

This study aimed to determine the in vivo effectiveness of the ethanolic extract of Piper betle L. leaves against Staphylococcus aureus-infected wounds in mice and its antimicrobial properties on clinical isolates of multiple drug-resistant bacterial pathogens. Twenty mice were divided into four groups. Wounds were created in all mice under anesthesia by excision from the dorsal skin down to the subcutaneous fat and inoculating with S. aureus. After 24 h, the wound of each mouse was treated once daily by application of the respective cream. Group I was treated with mupirocin antibacterial cream; Group II received a cream base containing no active ingredient; Groups III and IV were treated with 2.5% and 5.0% concentrations of P. betle cream, respectively. Further, an in vitro study was performed by adding undiluted, 1:50 and 1:100 dilutions of the four studied creams in normal saline containing 1.5 × 108 CFU/mL of the following bacteria: antimicrobial-susceptible S. aureus, Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant S. aureus, extended-spectrum ß-lactamase-producing Escherichia coli, vancomycin-resistant Enterococcus, metallo-ßlactamase-producing P. aeruginosa and carbapenem-resistant Klebsiella pneumoniae. The mice in Groups III and IV had significantly faster wound contraction and significantly shorter reepithelialization time than Group II (p < 0.05), which were not significantly different from Group I (p > 0.05). P. betle creams inhibited all studied bacterial strains at full concentration and at a dilution of 1:50. The inhibitory effect was more significant than Groups I and II (p < 0.05), except on S. aureus. Specifically, S. aureus inhibition was not significantly different for Groups III and IV (p > 0.05) when compared with Group I. Cream formulations derived from P. betle ethanolic extract have great potential as antimicrobial agents for the treatment of wound infection. Further clinical tests are recommended to determine the safety and efficacy of these formulations in other mammalian species.

5.
Andes Pediatr ; 92(2): 226-233, 2021 Apr.
Artículo en Español | MEDLINE | ID: mdl-34106161

RESUMEN

INTRODUCTION: The prevalence of asthma in Chile ranges from 10.2 to 14.9%. In previous studies, the Araucanía Region has not been included. OBJECTIVE: To determine the prevalence of asthma in the school po pulation of the Araucanía Region. SUBJECTS AND METHOD: The ISAAC questionnaires were used for asthma symptoms in addition to a questionnaire for recording sociodemographic data, belonging to the Mapuche ethnicity, type of heating, exposure to indoor air pollution, and family history. The Binomial Regression Model was used to evaluate the effect of each of the different variables of inter est, adjusting by age groups (6-7 and 13-14 years). The model also evaluated the additive interaction between these variables and age. RESULTS: 823 surveys were applied, where the prevalence of asthma was 14.2% and 23.2% in the 6-7 year old group and the 13-14 year old group, respectively. 43.7% de clare to be Mapuche, 32.9% live in rural areas, and 81.4% use firewood as a heating method. Through binomial regression model analysis, where for the study group, living in the coastal commune was significantly associated with a lower prevalence of asthma (-13.2% [CI: -17.7 to -8.6]. The history of an asthmatic mother was significantly associated with a higher prevalence of asthma (17.9% [CI: 2.7 to 33.1]. Living in a rural area, to be Mapuche or the type of heating used, showed differences statistically significant (p 0.18, p 0.609 and p 0.480, respectively) Conclusion: 13-14 year-olds school children in the Araucanía Region presented a higher prevalence of asthma. There was an association with asthma in the mother where this increase is not associated with living in a rural area, to be Ma puche or type of heating.


Asunto(s)
Asma/epidemiología , Pueblos Indígenas/estadística & datos numéricos , Distribución por Edad , Factores de Edad , Contaminación del Aire Interior/estadística & datos numéricos , Asma/etnología , Niño , Chile/epidemiología , Chile/etnología , Estudios Transversales , Femenino , Calefacción/métodos , Humanos , Madres , Prevalencia , Factores de Riesgo , Población Rural
6.
Med Intensiva (Engl Ed) ; 45(6): 332-346, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34127405

RESUMEN

OBJECTIVE: To assess the epidemiology and outcome at discharge of cancer patients requiring admission to the Intensive Care Unit (ICU). DESIGN: A descriptive observational study was made of data from the ENVIN-HELICS registry, combined with specifically compiled variables. Comparisons were made between patients with and without neoplastic disease, and groups of cancer patients with a poorer outcome were identified. SETTING: Intensive Care Units participating in ENVIN-HELICS 2018, with voluntary participation in the oncological registry. PATIENTS: Subjects admitted during over 24 h and diagnosed with cancer in the last 5 years. PRIMARY ENDPOINTS: The general epidemiological endpoints of the ENVIN-HELICS registry and cancer-related variables. RESULTS: Of the 92 ICUs with full data, a total of 11,796 patients were selected, of which 1786 (15.1%) were cancer patients. The proportion of cancer patients per Unit proved highly variable (1%-48%). In-ICU mortality was higher among the cancer patients than in the non-oncological subjects (12.3% versus 8.9%; p < .001). Elective postoperative (46.7%) or emergency admission (15.3%) predominated in the cancer patients. Patients with medical disease were in more serious condition, with longer stay and greater mortality (27.5%). The patients admitted to the ICU due to nonsurgical disease related to cancer exhibited the highest mortality rate (31.4%). CONCLUSIONS: Great variability was recorded in the percentage of cancer patients in the different ICUs. A total of 46.7% of the patients were admitted after undergoing scheduled surgery. The highest mortality rate corresponded to patients with medical disease (27.5%), and to those admitted due to cancer-related complications (31.4%).


Asunto(s)
Unidades de Cuidados Intensivos , Neoplasias , Cuidados Críticos , Mortalidad Hospitalaria , Humanos , Neoplasias/epidemiología , Pronóstico
8.
Rev. patol. respir ; 24(1): 29-31, ene.-mar. 2021. ilus
Artículo en Español | IBECS | ID: ibc-202343

RESUMEN

El neumotórax catamenial es una patología poco frecuente que afecta a mujeres en edad fértil. La asociación con hernia diafragmática hepática es rara con pocos casos reportados en la literatura. Se presenta un caso clínico junto a una revisión de la literatura ya que es un caso de interés por el modo de resolución y porque existen controversias en cuanto a su tratamiento. Se destaca que para realizar el diagnóstico es importante una alta sospecha clínica. La videotoracoscopia es un buen método para el tratamiento quirúrgico de esta enfermedad y si bien no existen aún datos concluyentes acerca del mejor manejo del neumotórax catamenial, experiencias de la literatura respaldan mejores resultados de la cirugía respecto a la terapia hormonal en término de recurrencia


Catamenial pneumothorax is a rare disease that affects women of childbearing age. The association with diaphragmatic hepatic hernia is rare with few cases reported in the literature. A clinical case is presented together with a review of the literature since it is a case of interest due to the way of resolution and because there are controversies regarding its treatment. It is emphasized that a high clinical suspicion is important to make the diagnosis. Videothoracoscopy is a good method for the surgical treatment of this disease and although there are still no conclusive data about the best management of catamenial pneumothorax, experiences in the literature support better results of surgery with respect to hormonal therapy in terms of recurrence


Asunto(s)
Humanos , Femenino , Adulto , Neumotórax/cirugía , Hernia Diafragmática/cirugía , Hepatopatías/cirugía , Cirugía Torácica Asistida por Video/métodos , Endometriosis/cirugía , Neumotórax/etiología , Hernia Diafragmática/complicaciones , Hepatopatías/complicaciones , Endometriosis/complicaciones , Resultado del Tratamiento
9.
Actas urol. esp ; 45(2): 103-115, mar. 2021. tab, graf
Artículo en Español | IBECS | ID: ibc-201615

RESUMEN

CONTEXTO: El desarrollo de protocolos ERAS (Enhanced Recovery After Surgery) en pacientes sometidos a cirugía mayor ha aportado beneficios perioperatorios en diversas disciplinas. En urología, su principal aplicación se centra en pacientes sometidos a cistectomía radical. OBJETIVO: Revisión sistemática de la literatura disponible de protocolos ERAS aplicados a pacientes intervenidos de cistectomía radical, tanto a nivel de resultados perioperatorios como en el análisis de su implementación. Adquisición de la evidencia: Se realizó búsqueda bibliográfica en base de datos electrónicas Pubmed, Embase, Cochrane y Scopus, utilizando los términos «Cystectomy», «Enhanced Recovery After Surgery» y «Fast-Track». Se seleccionaron estudios aleatorizados y no aleatorizados que comparasen la implementación de un protocolo ERAS en pacientes sometidos a cistectomía radical frente a un protocolo tradicional. Síntesis de la evidencia: Se identificaron 869 artículos; 25 fueron seleccionados para el análisis final: 22 estudios no aleatorizados y 3 aleatorizados. No se detectaron diferencias en cuanto a características demográficas entre los distintos estudios. Se identificaron diferencias estadísticamente significativas a favor del protocolo ERAS en tiempo de estancia hospitalaria, tasa de complicaciones mayores, tiempo a primera deambulación y recuperación intestinal. En el análisis de protocolos se detectó una alta variabilidad, tanto en número de ítems como en método de implementación. CONCLUSIONES: El carácter multidisciplinar y el número de ítems de los protocolos ERAS conlleva una alta heterogeneidad en su implementación. Se requieren más estudios aleatorizados, estandarización a la hora de reportar y analizar resultados, así como un análisis sistemático de la adherencia posterior para aumentar la comparabilidad entre grupos


CONTEXT: The development of ERAS (Enhanced Recovery After Surgery) protocols in patients undergoing major surgery has brought perioperative benefits in several disciplines. Its main application in urology is focused on patients undergoing radical cystectomy. OBJECTIVE: Systematic review of the available literature on ERAS protocols applied to patients undergoing radical cystectomy in terms of perioperative outcomes as well in the analysis of their implementation. Evidence acquisition: A bibliographic search was conducted in the electronic databases PubMed, Embase, Cochrane and Scopus, using the terms «Cystectomy», «Enhanced Recovery After Surgery» and «Fast-Track». Randomized and non-randomized studies that compared the implementation of an ERAS protocol versus a traditional protocol in patients undergoing radical cystectomy were selected. Evidence synthesis: 869 articles were identified; 25 were selected for final analysis: 22 non-randomized and 3 randomized studies. No differences were observed in terms of demographic characteristics between studies. Statistically significant differences were identified in favor of the ERAS protocol: length of hospital stay, major complication rate, time to first ambulation and return of bowel function. In the analysis of protocols, a high variability was detected in the number of items and in the implementation method. CONCLUSIONS: The multidisciplinary nature and the number of items of the ERAS protocols imply a high heterogeneity in their implementation. Further randomized studies, standardized reporting and analyzing results, as well as a systematic analysis of subsequent adherence are required to increase comparability between groups


Asunto(s)
Humanos , Recuperación de la Función , Atención Perioperativa/normas , Cistectomía/rehabilitación , Atención Perioperativa/métodos , Cistectomía/métodos , Cuidados Posoperatorios , Tiempo de Internación
10.
Rev Esp Quimioter ; 34(2): 136-140, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33675220

RESUMEN

OBJECTIVE: Controversial results on remdesivir efficacy have been reported. We aimed to report our real-life experience with the use of remdesivir from its availability in Spain. METHODS: We performed a descriptive study of all patients admitted for ≥48 hours with confirmed COVID-19 who received remdesivir between the 1st of July and the 30th of September 2020. RESULTS: A total of 123 patients out of 242 admitted with COVID-19 at our hospital (50.8%) received remdesivir. Median age was 58 years, 61% were males and 56.9 % received at least one anti-inflammatory treatment. No adverse events requiring remdesivir discontinuation were reported. The need of intensive care unit admission, mechanical ventilation and 30-days mortality were 19.5%, 7.3% and 4.1%, respectively. CONCLUSIONS: In our real-life experience, the use of remdesivir in hospitalized patients with COVID-19 was associated with a low mortality rate and good safety profile.


Asunto(s)
Adenosina Monofosfato/análogos & derivados , Alanina/análogos & derivados , Antivirales/uso terapéutico , COVID-19/tratamiento farmacológico , Pacientes Internos , Adenosina Monofosfato/uso terapéutico , Anciano , Alanina/uso terapéutico , Antiinflamatorios/uso terapéutico , Anticuerpos Monoclonales Humanizados/uso terapéutico , COVID-19/mortalidad , Estudios de Cohortes , Dexametasona/uso terapéutico , Femenino , Mortalidad Hospitalaria , Humanos , Unidades de Cuidados Intensivos/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Respiración Artificial/estadística & datos numéricos , España/epidemiología , Resultado del Tratamiento
11.
Ir J Psychol Med ; : 1-6, 2021 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-33526156

RESUMEN

OBJECTIVE: The aim of this study is to test the psychometric properties of the Spanish validation of the Fear of COVID-19 Scale (FCV-19S) in a Paraguayan population. METHODS: Participants were recruited through an Internet-based survey. All participants whose scores in the Hospital Anxiety and Depression Scale (HADS) and The Fear Questionnaire (FQ) were greater than zero were included. 1245 subjects responded voluntarily: 1077 subjects, scoring >0, were considered. RESULTS: To establish construct validity of the FCV-19S, an exploratory factor analysis was performed using the KMO test, which was adequate, and the Bartlett sphericity test, which was significant (p <.0001). The CFI, NFI, GFI, TLI and RMSEA indices were used to evaluate the model and showed good adjustment. Cronbach's α showed valid internal consistency (α = 0.86). This validation was supported by significant correlation (p <.001) with the HADS scale for anxiety and depression and with the FQ scale for specific phobia. CONCLUSIONS: The Spanish version of the FCV-19S is a 7-item scale with two dimensions, psychological symptoms and physiological symptoms, which demonstrated robust psychometric properties in a Paraguayan population.

12.
Med Intensiva ; 45(6): 332-346, 2021.
Artículo en Inglés, Español | MEDLINE | ID: mdl-32307264

RESUMEN

OBJECTIVE: To assess the epidemiology and outcome at discharge of cancer patients requiring admission to the Intensive Care Unit (ICU). DESIGN: A descriptive observational study was made of data from the ENVIN-HELICS registry, combined with specifically compiled variables. Comparisons were made between patients with and without neoplastic disease, and groups of cancer patients with a poorer outcome were identified. SETTING: Intensive Care Units participating in ENVIN-HELICS 2018, with voluntary participation in the oncological registry. PATIENTS: Subjects admitted during over 24hours and diagnosed with cancer in the last 5 years. PRIMARY ENDPOINTS: The general epidemiological endpoints of the ENVIN-HELICS registry and cancer-related variables. RESULTS: Of the 92 ICUs with full data, a total of 11,796 patients were selected, of which 1786 (15.1%) were cancer patients. The proportion of cancer patients per Unit proved highly variable (1-48%). In-ICU mortality was higher among the cancer patients than in the non-oncological subjects (12.3% versus 8.9%; P<.001). Elective postoperative (46.7%) or emergency admission (15.3%) predominated in the cancer patients. Patients with medical disease were in more serious condition, with longer stay and greater mortality (27.5%). The patients admitted in ICU due to nonsurgical disease related to cancer exhibited the highest mortality rate (31.4%). CONCLUSIONS: Great variability was recorded in the percentage of cancer patients in the different ICUs. A total of 46.7% of the patients were admitted after undergoing scheduled surgery. The highest mortality rate corresponded to patients with medical disease (27.5%), and to those admitted due to cancer-related complications (31.4%).

13.
Actas Urol Esp (Engl Ed) ; 45(2): 103-115, 2021 Mar.
Artículo en Inglés, Español | MEDLINE | ID: mdl-32709429

RESUMEN

CONTEXT: The development of ERAS (Enhanced Recovery After Surgery) protocols in patients undergoing major surgery has brought perioperative benefits in several disciplines. Its main application in urology is focused on patients undergoing radical cystectomy. OBJECTIVE: Systematic review of the available literature on ERAS protocols applied to patients undergoing radical cystectomy in terms of perioperative outcomes as well in the analysis of their implementation. EVIDENCE ACQUISITION: A bibliographic search was conducted in the electronic databases PubMed, Embase, Cochrane and Scopus, using the terms «Cystectomy¼, «Enhanced Recovery After Surgery¼ and «Fast-Track¼. Randomized and non-randomized studies that compared the implementation of an ERAS protocol versus a traditional protocol in patients undergoing radical cystectomy were selected. EVIDENCE SYNTHESIS: 869 articles were identified; 25 were selected for final analysis: 22 non-randomized and 3 randomized studies. No differences were observed in terms of demographic characteristics between studies. Statistically significant differences were identified in favor of the ERAS protocol: length of hospital stay, major complication rate, time to first ambulation and return of bowel function. In the analysis of protocols, a high variability was detected in the number of items and in the implementation method. CONCLUSIONS: The multidisciplinary nature and the number of items of the ERAS protocols imply a high heterogeneity in their implementation. Further randomized studies, standardized reporting and analyzing results, as well as a systematic analysis of subsequent adherence are required to increase comparability between groups.


Asunto(s)
Cistectomía/normas , Recuperación Mejorada Después de la Cirugía , Neoplasias de la Vejiga Urinaria/cirugía , Protocolos Clínicos , Cistectomía/métodos , Humanos
15.
Appl Radiat Isot ; 166: 109359, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32739748

RESUMEN

Ionizing and non-ionizing radiations are part of our daily life, and when organisms are exposed to them for a long time, they may experience their lethal or sublethal effects. For this reason, technologies have been created to quantify them. In this study, Internet of Things (IoT) was used through connecting gamma meters and a low-cost UV radiation device. The validation of this structure was performed with meters calibrated in certified laboratories. The validation results matched those obtained by the other devices, with an error of 2%.

16.
Salud Publica Mex ; 62(4): 388-401, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32549083

RESUMEN

OBJECTIVE: To determine the abundance and geographic distribution of the main malaria vectors, which are influenced by habitat characteristics and ecological factors that directly impact adult density and the dynamics of malaria transmission in Mexico. MATERIALS AND METHODS: Samples of larvae were collected from 19 states in Mexico. Each larval habitat was characterized in situ determining the following parameters: water depth, turbidity, percentage of vegetation cover, amount of detritus, presence of algae, light intensity, type of vegetation, amount of predators, habitat stability, altitude, and hydrologic type. RESULTS: A total of 21 687 larvae corresponding to 13 anopheline species were obtained from 149 aquatic habitats. The most abundant species were Anopheles pseudopunctipennis (52.91%), An. albimanus (39.14%) and An. franciscanus (5.29%). The multiple logistic regression analysis showed a negative association between An. pseudopunctipennis and water turbidity (ß=-1.342; Wald=6.122; p=0.013) and the amount of detritus (ß=-2.206; Wald=3.642; p=0.050). While in An. albimanus, there was a significant positive association with water turbidity (ß=1.344; Wald=4.256; p=0.039), a negative correlation was found with the altitude (ß=-3.445; Wald=5.407; p =0.020). The highest mosquito species diversity index was found in Chiapas (Fisher's α=1.20) and the lowest diversity in Chihuahua (Fisher's α=0.26). The greatest richness was found in streams (n=11). CONCLUSIONS: The two most abundant species were: An. albimanus and An. pseudopunctipennis. Detailed knowledge of the distribution and characteristics of their larval habitats will be useful for the effective implementation of control strategies in Mexico.


Asunto(s)
Anopheles , Ecosistema , Mosquitos Vectores , Animales , Larva , Malaria/transmisión , México , Densidad de Población , Análisis de Regresión , Especificidad de la Especie , Agua/parasitología
17.
Salud Publica Mex ; 62(4): 402-409, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32516870

RESUMEN

OBJECTIVE: The feasibility of the use of WHO impregnated paper and biochemical assays to determine lethal concentrations (LC50 and LC99) and insecticide metabolic enzyme levels of Triatoma dimidiata. MATERIALS AND METHODS: LC50 and LC99 were calculated with WHO papers impregnated at different concentrations of malathion, propoxur and deltamethrin; the percentage of insensitive acetylcholinesterase (iAChE); and the levels of esterases, glutathione S-transferases, and monooxygenases in laboratory nymphs of the first stage (5 to 7 days), were undertaken using the WHO biochemical assays. RESULTS: Respectively the LC50 and LC99 µg/cm2 obtained for malathion were 43.83 and 114.38, propoxur 4.71 and 19.29, and deltamethrin 5.80 and 40.46. A 30% of the population had an iAChE, and only a few individuals had high P450 and ß-eterase levels. CONCLUSIONS: Impregnated papers and biochemical tests developed by WHO for other insects, proved to be feasible methods in monitoring insecticide resistance and metabolic enzymes involved in T. dimidiata.


Asunto(s)
Resistencia a los Insecticidas , Insecticidas/toxicidad , Malatión/toxicidad , Nitrilos/toxicidad , Propoxur/toxicidad , Piretrinas/toxicidad , Triatoma/efectos de los fármacos , Acetilcolinesterasa/análisis , Animales , Sistema Enzimático del Citocromo P-450/análisis , Esterasas/análisis , Estudios de Factibilidad , Glutatión Transferasa/análisis , Dosificación Letal Mediana , Oxigenasas de Función Mixta/análisis , Ninfa/efectos de los fármacos , Ninfa/enzimología , Triatoma/enzimología , Organización Mundial de la Salud
18.
Appl Opt ; 59(13): D39-D42, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32400621

RESUMEN

Reflectance anisotropy spectroscopy (RAS) is a highly sensitive optical probe for the real-time study of the epitaxial growth of zincblende semiconductors. Here we report on (1) non-equilibrium RAS spectra acquired in real time during the homoepitaxial growth of GaAs, and (2) RAS spectra for GaAs surfaces under equilibrium with several arsenic overpressures. We show that in both cases RAS spectra can be decomposed into two basic components, each with a characteristic line shape. We further show that both dynamic and equilibrium RAS spectra are described by the same pair of basic components. We conclude that the time evolution of non-equilibrium RAS spectra acquired during the epitaxial growth can be described in terms of RAS spectra for equilibrium surfaces. The results reported here should be useful for the interpretation of the physics underlying the rapid time evolution of dynamic RAS spectra during the first monolayer growth. Thus, we show that RAS constitutes a valuable tool for the study of epitaxial growth mechanisms.

19.
Plant Physiol Biochem ; 151: 352-361, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32272353

RESUMEN

The S-specific pollen rejection response in Nicotiana depends on the interaction between S-RNase and a suite of SLF proteins. However, the biochemical pathway requires other essential proteins. One of them is the stigmatic protein NaStEP, which belongs to the Kunitz-type protease inhibitor family. Within the pollen tubes, NaStEP is a positive regulator of HT-B stability, likely inhibiting its degradation and, additionally, interacts with NaSIPP, a mitochondrial phosphate carrier. To gain a deeper understanding of the biochemical role of NaStEP in pollen rejection, we evaluated whether the activity of NaStEP as protease inhibitor is specific to a particular type of protease and whether it has the function of a voltage-dependent channel (VDC) blocker. Our findings indicate that, in vitro, NaStEP inhibits a subtilisin-like protease in an irreversible manner, but not other proteases, such as thermolysin and papain. Furthermore, we found that subtilisin processes the native NaStEP (24 kDa) into two lower molecular weight peptides of 21 and 14 kDa. Moreover, when we incubated NaStEP along with Xenopus leavis oocytes expressing the voltage-dependent potassium channel Kv 1.3, the current was blocked, indicating that NaStEP acts as a VDC blocker. These data allow us to propose NaStEP acts as a key molecule with two functions, one protecting HT-B from degradation by inhibiting a subtilisin-like protease and the second one by forming a complex with a mitochondrial VDC that could destabilize the mitochondria to trigger cell death, which would reinforce S-specific pollen rejection in Nicotiana.


Asunto(s)
Proteínas de Plantas , Tabaco , Secuencia de Aminoácidos , Moduladores del Transporte de Membrana/metabolismo , Péptido Hidrolasas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Inhibidores de Proteasas , Tabaco/genética , Tabaco/metabolismo
20.
Nanomaterials (Basel) ; 10(4)2020 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-32340208

RESUMEN

Different studies in the literature indicate the effectiveness of CNTs as reinforcing materials in cement-matrix composites due to their high mechanical strength. Nevertheless, their incorporation into cement presents some difficulties due to their tendency to agglomerate, yielding a non-homogeneous dispersion in the paste mix that results in a poor cement-CNTs interaction. This makes the surface modification of the CNTs by introducing functional groups on the surface necessary. In this study, three different treatments for incorporating polar oxygen functional groups onto the surface of carbon nanotubes have been carried out, with the objective of evaluating the influence of the type and oxidation degree on the mechanical and electrical properties and in strain-sensing function of cement pastes containing CNTs. One treatment is in liquid phase (surface oxidation with HNO3/H2SO4), the second is in gas phase (O3 treatment at 25 and 160 °C), and a third is a combination of gas-phase O3 treatment plus NaOH liquid phase. The electrical conductivity of cement pastes increased with O3- and O3-NaOH-treated CNTs with respect to non-treated ones. Furthermore, the oxygen functionalization treatments clearly improve the strain sensing performance of the CNT-cement pastes, particularly in terms of the accuracy of the linear correlation between the resistance and the stress, as well as the increase in the gage factor from 28 to 65. Additionally, the incorporation of either non-functionalized or functionalized CNTs did not produce any significant modification of the mechanical properties of CNTs. Therefore, the functionalization of CNTs favours the de-agglomeration of CNTs in the cement matrix and consequently, the electrical conductivity, without affecting the mechanical behaviour.

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