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1.
Sci Rep ; 12(1): 5500, 2022 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-35365670

RESUMEN

The high flux magmatism, crustal shortening/extension and plateau formation in Cordilleran orogenic systems have been explained by removal of lithosphere (lower crust and the sub-arc mantle lithosphere) that develops beneath the magmatic arc and hinterland regions. However, the primary role of this process driving surface uplift, and crustal deformation is not well understood. Here, reconciling geodynamic model predictions with lithospheric structure and paleoelevation estimates, we suggest that viscous drip-type lithospheric removal from beneath the Central (Peruvian) Andes can explain several tectonic features: (1) "double humped" shaped/axisymmetric topographic profile and rapid surface rise (up to 1.2 km in ~ 4.31 Myrs); (2) thicker crust associated with the lower surface elevation of the Altiplano plateau (Lake Titicaca region) (negative residual topography) and higher topography and thinner crust of Western and Eastern Cordilleras (positive residual topography); and (3) faster wave speed (colder)/sub-Moho anomaly underlying the Altiplano, surrounded by slower speed anomalies on both western arc-forearc areas and parts of the eastern Cordillera and Sub-Andes. Our results emphasize the important role of lithospheric drip and associated mantle dynamics in the transient evolution of Andean orogeny controlling surface uplift and crustal flow and thickening.

2.
Br Poult Sci ; 63(3): 332-339, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-34738498

RESUMEN

1. Aflatoxins (AFs) are metabolites which especially have toxic effects on proteins, and are detoxified by the aflatoxin-B1 aldehyde reductase (AFAR) pathway. In this pathway, the aldo-keto reductase family 7, member A2 (AKR7A2) enzyme, which is controlled by nucleic-related erythroid factor 2 (Nrf2), plays an active role. However, data on the efficacy of this critical pathway in broilers is limited.2. The aim of the following study was to investigate the changes in the expression levels of AKR7A2, Nrf2, and caspase-3, and the effects of Nigella sativa seeds (NS), thymoquinone (TMQ), and bentonite (BNT) in broilers exposed to AFs.3. One-hundred broilers were divided into ten groups (control (CNT); AF; NS; TMQ; BNT; AF+TMQ; AF+NS; AF+BNT; AF+BNT+NS; AF+BNT+TMQ) and fed for 28 d. AF, TMQ, NS and BNT were added to diets at levels of 2 mg/kg, 300 mg/kg, 50 g/kg and 10 g/kg respectively.4. The addition of AF to the diet decreased AKR7A2 and Nrf2 levels dramatically, but increased caspase-3 (P < 0.01). TMQ, NS and BNT additions to the diet eliminated all negative effects caused by AF (P < 0.01); and AKR7A2 and Nrf2 were further raised in TMQ and NS groups when compared to the control group. TMQ and NS showed a positive effect on detoxification parameters when given together with BNT.5. Supplementation with NS and TMQ enhanced AF detoxification via the AFAR pathway, by increasing AKR7A2 and Nrf2 levels, in addition to reducing hepatocyte apoptosis.


Asunto(s)
Aflatoxinas , Enfermedades Transmitidas por los Alimentos , Micotoxicosis , Nigella sativa , Aldehído Reductasa/genética , Aldehído Reductasa/metabolismo , Animales , Bentonita/metabolismo , Benzoquinonas , Caspasa 3/genética , Caspasa 3/metabolismo , Pollos/metabolismo , Regulación hacia Abajo , Enfermedades Transmitidas por los Alimentos/veterinaria , Micotoxicosis/veterinaria , Factor 2 Relacionado con NF-E2/metabolismo , Nigella sativa/metabolismo
3.
J Laryngol Otol ; 134(8): 661-664, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32613918

RESUMEN

BACKGROUND: The following position statement from the Union of the European Phoniatricians, updated on 25th May 2020 (superseding the previous statement issued on 21st April 2020), contains a series of recommendations for phoniatricians and ENT surgeons who provide and/or run voice, swallowing, speech and language, or paediatric audiology services. OBJECTIVES: This material specifically aims to inform clinical practices in countries where clinics and operating theatres are reopening for elective work. It endeavours to present a current European view in relation to common procedures, many of which fall under the aegis of aerosol generating procedures. CONCLUSION: As evidence continues to build, some of the recommended practices will undoubtedly evolve, but it is hoped that the updated position statement will offer clinicians precepts on safe clinical practice.


Asunto(s)
Audiología/métodos , Betacoronavirus/aislamiento & purificación , Infecciones por Coronavirus/prevención & control , Otolaringología/métodos , Pandemias/prevención & control , Neumonía Viral/prevención & control , Audiología/normas , COVID-19 , Niño , Preescolar , Infecciones por Coronavirus/epidemiología , Infecciones por Coronavirus/virología , Trastornos de Deglución/diagnóstico , Trastornos de Deglución/cirugía , Trastornos de Deglución/virología , Europa (Continente)/epidemiología , Humanos , Exámenes Obligatorios/normas , Otolaringología/normas , Pediatría/normas , Equipo de Protección Personal/normas , Equipo de Protección Personal/provisión & distribución , Neumonía Viral/epidemiología , Neumonía Viral/virología , Guías de Práctica Clínica como Asunto , SARS-CoV-2 , Sociedades Médicas/organización & administración , Trastornos de la Voz/diagnóstico , Trastornos de la Voz/cirugía , Trastornos de la Voz/virología
4.
ACS Sens ; 3(9): 1773-1781, 2018 09 28.
Artículo en Inglés | MEDLINE | ID: mdl-30156096

RESUMEN

Clinical diagnostic assays that monitor redox enzyme activity are widely used in small, low-cost readout devices for point-of-care monitoring (e.g., a glucometer); however, monitoring non-redox enzymes in real-time using compact electronic devices remains a challenge. We address this problem by using a highly scalable nanogap sensor array to observe electrochemical signals generated by a model non-redox enzyme system, the DNA polymerase-catalyzed incorporation of four modified, redox-tagged nucleotides. Using deoxynucleoside triphosphates (dNTPs) tagged with para-aminophenyl monophosphate (pAPP) to form pAP-deoxyribonucleoside tetra-phosphates (AP-dN4Ps), incorporation of the nucleotide analogs by DNA polymerase results in the release of redox inactive pAP-triphosphates (pAPP3) that are converted to redox active small molecules para-aminophenol (pAP) in the presence of phosphatase. In this work, cyclic enzymatic reactions that generated many copies of pAP at each base incorporation site of a DNA template in combination with the highly confined nature of the planar nanogap transducers ( z = 50 nm) produced electrochemical signals that were amplified up to 100,000×. We observed that the maximum signal level and amplification level were dependent on a combination of factors including the base structure of the incorporated nucleotide analogs, nanogap electrode materials, and electrode surface coating. In addition, electrochemical signal amplification by redox cycling in the nanogap is independent of the in-plane geometry of the transducer, thus allowing the nanogap sensors to be highly scalable. Finally, when the DNA template concentration was constrained, the DNA polymerase assay exhibited different zero-order reaction kinetics for each type of base incorporation reaction, resolving the closely related nucleotide analogs.


Asunto(s)
ADN Polimerasa I/análisis , Técnicas Electroquímicas/métodos , Pruebas de Enzimas/métodos , Fosfatasa Alcalina/química , Aminofenoles/química , Compuestos de Anilina/química , Animales , Bovinos , ADN/química , ADN Polimerasa I/química , Escherichia coli/enzimología , Proteínas de Escherichia coli/análisis , Proteínas de Escherichia coli/química , Exodesoxirribonucleasas/química , Nucleótidos/química , Compuestos Organofosforados/química , Oxidación-Reducción
5.
Eye (Lond) ; 32(4): 763-767, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29386615

RESUMEN

PurposeFibromyalgia (FM) is a chronic pain disorder associated with pain and hypersensitivity in various parts of the body. The aim of this study was to understand whether changes in corneal sensitivity were associated with the subjective complaints of these patients.Patients and methodsIn this study, we included 36 patients with FM (30 female, 6 male, mean age: 46.7±9.2 years) and 39 healthy control subjects (33 females, 6 males, mean age: 44.3±7.6 years). We performed a detailed ophthalmological examination, measured tear film breakup time (TBUT), and performed Schirmer I test without anesthetic (SIT). Only patients that did not have any eye disease were included in this study. Subjective complaints of the patients were evaluated with ocular surface disease index (OSDI) scores and the corneal sensation was evaluated with Cochet-Bonnet esthesiometer.ResultsThere was no significant difference between the groups for age, sex, and visual acuity. Both SIT (16.1 mm vs 15.3 mm, P=0.36) and TBUT results (17.8 s vs 18.8 s, P=0.40) were similar in FM group and the controls subjects. However, corneal sensations in central (60.0 mm vs 55.0 mm, P=0.03), superior (57.5 mm vs 50.0 mm, P=0.005), and inferior (53.89 mm vs 46.03 mm, P<0.001) regions were significantly increased in FM patients. There was a significant positive correlation between corneal sensation and OSDI scores.ConclusionIn this study, we have demonstrated that the patients with FM have increased corneal sensitivity and have related ocular surface complaints similar to dry eye disease in the absence of it.


Asunto(s)
Córnea/fisiología , Síndromes de Ojo Seco/etiología , Dolor Ocular/etiología , Fibromialgia/fisiopatología , Adulto , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Lágrimas/metabolismo , Agudeza Visual
6.
Nat Commun ; 8(1): 1538, 2017 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-29142259

RESUMEN

Lithospheric drips have been interpreted for various regions around the globe to account for the recycling of the continental lithosphere and rapid plateau uplift. However, the validity of such hypothesis is not well documented in the context of geological, geophysical and petrological observations that are tested against geodynamical models. Here we propose that the folding of the Central Anatolian (Kirsehir) arc led to thickening of the lithosphere and onset of "dripping" of the arc root. Our geodynamic model explains the seismic data showing missing lithosphere and a remnant structure characteristic of a dripping arc root, as well as enigmatic >1 km uplift over the entire plateau, Cappadocia and Galatia volcanism at the southern and northern plateau margins since ~10 Ma, respectively. Models show that arc root removal yields initial surface subsidence that inverts >1 km of uplift as the vertical loading and crustal deformation change during drip evolution.

7.
Hernia ; 19(6): 879-85, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26486322

RESUMEN

PURPOSE: We aimed to compare tacker and suture techniques for peritoneal closure with respect to patient outcomes. METHODS: A total of 64 patients were included in the study, 32 being in the tacker group and 32 in the suture group. All patients underwent laparoscopic TAPP inguinal hernia repair. Both groups were compared with respect to age, sex, duration of peritoneal closure and the operation, hernia type, the number of tackers used for mesh fixation, postoperative complication rate, visual analogue scale (VAS) scores on 1st, 7th, and 30th days, duration of follow-up, and recurrence rates. RESULTS: Duration of peritoneal closure and the operation was significantly shorter in the tacker group compared to the suture group (p < 0.001, p = 0.008, respectively). Statistical analysis with the two-way analysis of variance method revealed that mesh fixation with one or two tackers did not influence postoperative pain. VAS 1 was significantly lower in patients with peritoneal closure with suture compared to the patients undergoing peritoneal closure with tacker (p = 0.027). VAS 7 and VAS 30 were lower for peritoneal closure with suture versus tacker, although the difference did not reach statistical significance (p = 0.064, p = 0.294, respectively). We observed no recurrence at an average of 21-month follow-up. CONCLUSIONS: Tacker and suture appeared to have a comparable safety for peritoneal closure in laparoscopic TAPP inguinal hernia operation. It can be suggested that peritoneal closure with tacker increased short-term pain, independent of the number of tackers used for mesh fixation. Long-term pain was similar in both groups.


Asunto(s)
Hernia Femoral/cirugía , Hernia Inguinal/cirugía , Herniorrafia/métodos , Peritoneo/cirugía , Adulto , Anciano , Femenino , Humanos , Laparoscopía , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Método Simple Ciego , Mallas Quirúrgicas , Técnicas de Sutura , Suturas
8.
Artículo en Inglés | MEDLINE | ID: mdl-25474788

RESUMEN

Using the small-signal electrical equivalent circuit of a capacitive micromachined ultrasonic transducer (CMUT) cell, along with the self and mutual radiation impedances of such cells, we present a computationally efficient method to predict the frequency response of a large CMUT element or array. The simulations show spurious resonances, which may degrade the performance of the array. We show that these unwanted resonances are due to dispersive Rayleigh-Bloch waves excited on the CMUT surface-liquid interface. We derive the dispersion relation of these waves for the purpose of predicting the resonance frequencies. The waves form standing waves at frequencies where the reflections from the edges of the element or the array result in a Fabry-Pérot resonator. High-order resonances are eliminated by a small loss in the individual cells, but low-order resonances remain even in the presence of significant loss. These resonances are reduced to tolerable levels when CMUT cells are built from larger and thicker plates at the expense of reduced bandwidth.

10.
Artículo en Inglés | MEDLINE | ID: mdl-23661137

RESUMEN

Capacitive micromachined ultrasonic transducers (CMUTs) are usually composed of large arrays of closely packed cells. In this work, we use an equivalent circuit model to analyze CMUT arrays with multiple cells. We study the effects of mutual acoustic interactions through the immersion medium caused by the pressure field generated by each cell acting upon the others. To do this, all the cells in the array are coupled through a radiation impedance matrix at their acoustic terminals. An accurate approximation for the mutual radiation impedance is defined between two circular cells, which can be used in large arrays to reduce computational complexity. Hence, a performance analysis of CMUT arrays can be accurately done with a circuit simulator. By using the proposed model, one can very rapidly obtain the linear frequency and nonlinear transient responses of arrays with an arbitrary number of CMUT cells. We performed several finite element method (FEM) simulations for arrays with small numbers of cells and showed that the results are very similar to those obtained by the equivalent circuit model.

11.
Avian Pathol ; 41(5): 469-77, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22974164

RESUMEN

Detrimental effects of aflatoxin B1 (AFB1) on the embryonic development of broiler tibia and its proximal growth plate were determined by means of histological, histometric and immunohistochemical methods. For this, 420 fertile eggs from parent stocks of Ross 308 broiler chickens were divided into five groups according to the proposed treatment: a control untreated group, a group injected with 30% ethanol and three further groups to be injected with 5, 15 or 40 ng AFB1. The eggs were injected into the air space prior to incubation. Five eggs from each group were opened at 9, 11, 13, 17, 19 and 21 days of incubation and tibial tissue samples were removed, dissected of muscle and connective tissues, and processed by means of routine histological techniques. The cell proliferation rate of the epiphyseal growth plate cells was determined by immunohistochemical assay of proliferating cell nuclear antigen (PCNA) expression. The results showed that both proliferative and hypertrophic zones narrowed significantly (P<0.05), when compared with the controls, in all of the AFB1-treated groups whereas the transitional zone thickened, especially in the group given 40 ng AFB1 group. The PCNA positivity indices of 15 and 40 ng AFB1-treated groups were significantly higher (P<0.05) on days 11, 13, 17, 19 and 21 of incubation. It was concluded that in ovo-administered AFB1 adversely affected embryonic development of the tibial growth plate, and that affected hatched broilers might also be more susceptible to skeletal disorders during growth.


Asunto(s)
Aflatoxina B1/toxicidad , Embrión de Pollo/efectos de los fármacos , Desarrollo Embrionario/efectos de los fármacos , Placa de Crecimiento/efectos de los fármacos , Tibia/efectos de los fármacos , Animales , Proliferación Celular/efectos de los fármacos , Embrión de Pollo/embriología , Embrión de Pollo/crecimiento & desarrollo , Pollos/crecimiento & desarrollo , Relación Dosis-Respuesta a Droga , Femenino , Placa de Crecimiento/embriología , Placa de Crecimiento/crecimiento & desarrollo , Inmunohistoquímica , Óvulo/efectos de los fármacos , Antígeno Nuclear de Célula en Proliferación/efectos de los fármacos , Antígeno Nuclear de Célula en Proliferación/metabolismo , Tibia/embriología , Tibia/crecimiento & desarrollo
12.
Artículo en Inglés | MEDLINE | ID: mdl-22899125

RESUMEN

This paper describes a correction and an extension in the previously published large signal equivalent circuit model for a circular capacitive micromachined ultrasonic transducer (CMUT) cell. The force model is rederived so that the energy and power is preserved in the equivalent circuit model. The model is able to predict the entire behavior of CMUT until the membrane touches the substrate. Many intrinsic properties of the CMUT cell, such as the collapse condition, collapse voltage, the voltage-displacement interrelation and the force equilibrium before and after collapse voltage in the presence of external static force, are obtained as a direct consequence of the model. The small signal equivalent circuit for any bias condition is obtained from the large signal model. The model can be implemented in circuit simulation tools and model predictions are in excellent agreement with finite element method simulations.

13.
Artículo en Inglés | MEDLINE | ID: mdl-22718878

RESUMEN

Capacitive micromachined ultrasonic transducers (CMUTs) have great potential to compete with piezoelectric transducers in high-power applications. As the output pressures increase, nonlinearity of CMUT must be reconsidered and optimization is required to reduce harmonic distortions. In this paper, we describe a design approach in which uncollapsed CMUT array elements are sized so as to operate at the maximum radiation impedance and have gap heights such that the generated electrostatic force can sustain a plate displacement with full swing at the given drive amplitude. The proposed design enables high output pressures and low harmonic distortions at the output. An equivalent circuit model of the array is used that accurately simulates the uncollapsed mode of operation. The model facilities the design of CMUT parameters for high-pressure output, without the intensive need for computationally involved FEM tools. The optimized design requires a relatively thick plate compared with a conventional CMUT plate. Thus, we used a silicon wafer as the CMUT plate. The fabrication process involves an anodic bonding process for bonding the silicon plate with the glass substrate. To eliminate the bias voltage, which may cause charging problems, the CMUT array is driven with large continuous wave signals at half of the resonant frequency. The fabricated arrays are tested in an oil tank by applying a 125-V peak 5-cycle burst sinusoidal signal at 1.44 MHz. The applied voltage is increased until the plate is about to touch the bottom electrode to get the maximum peak displacement. The observed pressure is about 1.8 MPa with -28 dBc second harmonic at the surface of the array.


Asunto(s)
Modelos Teóricos , Transductores , Ultrasonografía/instrumentación , Simulación por Computador , Impedancia Eléctrica , Electrónica Médica/instrumentación , Diseño de Equipo
14.
Analyst ; 137(6): 1351-62, 2012 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-22262038

RESUMEN

We introduce a label-free approach for sensing polymerase reactions on deoxyribonucleic acid (DNA) using a chelator-modified silicon-on-insulator field-effect transistor (SOI-FET) that exhibits selective and reversible electrical response to pyrophosphate anions. The chemical modification of the sensor surface was designed to include rolling-circle amplification (RCA) DNA colonies for locally enhanced pyrophosphate (PPi) signal generation and sensors with immobilized chelators for capture and surface-sensitive detection of diffusible reaction by-products. While detecting arrays of enzymatic base incorporation reactions is typically accomplished using optical fluorescence or chemiluminescence techniques, our results suggest that it is possible to develop scalable and portable PPi-specific sensors and platforms for broad biomedical applications such as DNA sequencing and microbe detection using surface-sensitive electrical readout techniques.


Asunto(s)
ADN Polimerasa Dirigida por ADN/metabolismo , ADN/química , ADN/metabolismo , Difosfatos/análisis , Técnicas Electroquímicas , Transistores Electrónicos , Secuencia de Bases , Técnicas Biosensibles , Quelantes/química , ADN Polimerasa Dirigida por ADN/química , Datos de Secuencia Molecular , Estructura Molecular , Silanos/química , Silicio/química , Propiedades de Superficie
15.
Hernia ; 16(5): 593-5, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21267614

RESUMEN

Presence of the ovary, fallopian tube, and uterus within an inguinal hernia is a rare condition. In this report, we describe the case of a 47-year-old female, multiparous patient with a giant omental lipoma (18 × 8 × 7 cm, 422 g) and left inguinal hernia. The uterus, left ovary, and fallopian tube were in the hernial sac. The presence of the uterus within the hernial sac accompanies mullerian anomalies, although, in this case, there was no such anomaly. To our knowledge, there have been no cases in the literature of a giant intraabdominal lipoma and a hernial sac containing the uterus, ovary, and fallopian tube, but a few cases of inguinal hernia involving the ovary, fallopian tube, and uterus have been reported. The aim of this case report was to call attention to the observation that the inguinal hernia seen in female patients may involve the ovary, fallopian tube, and uterus.


Asunto(s)
Hernia Inguinal/patología , Lipoma/complicaciones , Epiplón , Neoplasias Peritoneales/complicaciones , Trompas Uterinas/patología , Femenino , Hernia Inguinal/complicaciones , Hernia Inguinal/cirugía , Humanos , Lipoma/patología , Persona de Mediana Edad , Ovario/patología , Neoplasias Peritoneales/patología , Útero/patología
16.
Chem Commun (Camb) ; 47(29): 8310-2, 2011 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-21687892

RESUMEN

A new pyrophosphate (PPi) chelator was designed for surface-sensitive electrical detection of biomolecular reactions. This article describes the synthesis of the PPi-selective receptor, its surface immobilization and application to label-free electrical detection on a silicon-based field-effect transistor (FET) sensor.


Asunto(s)
Quelantes/química , Difosfatos/análisis , Técnicas Electroquímicas/métodos , Catecoles/química , Colorantes Fluorescentes/química , Silicio/química , Propiedades de Superficie , Transistores Electrónicos
17.
Biomed Microdevices ; 13(2): 335-44, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21203849

RESUMEN

Over the last decade, field-effect transistors (FETs) with nanoscale dimensions have emerged as possible label-free biological and chemical sensors capable of highly sensitive detection of various entities and processes. While significant progress has been made towards improving their sensitivity, much is yet to be explored in the study of various critical parameters, such as the choice of a sensing dielectric, the choice of applied front and back gate biases, the design of the device dimensions, and many others. In this work, we present a process to fabricate nanowire and nanoplate FETs with Al(2)O(3) gate dielectrics and we compare these devices with FETs with SiO(2) gate dielectrics. The use of a high-k dielectric such as Al(2)O(3) allows for the physical thickness of the gate dielectric to be thicker without losing sensitivity to charge, which then reduces leakage currents and results in devices that are highly robust in fluid. This optimized process results in devices stable for up to 8 h in fluidic environments. Using pH sensing as a benchmark, we show the importance of optimizing the device bias, particularly the back gate bias which modulates the effective channel thickness. We also demonstrate that devices with Al(2)O(3) gate dielectrics exhibit superior sensitivity to pH when compared to devices with SiO(2) gate dielectrics. Finally, we show that when the effective electrical silicon channel thickness is on the order of the Debye length, device response to pH is virtually independent of device width. These silicon FET sensors could become integral components of future silicon based Lab on Chip systems.


Asunto(s)
Óxido de Aluminio/química , Nanocables/química , Transistores Electrónicos , Impedancia Eléctrica , Concentración de Iones de Hidrógeno , Reproducibilidad de los Resultados , Silicio/química
18.
Anal Chem ; 83(3): 888-95, 2011 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-21214189

RESUMEN

We demonstrate the temperature mediated applications of a previously proposed novel localized dielectric heating method on the surface of dual purpose silicon field effect transistor (FET) sensor-heaters and perform modeling and characterization of the underlying mechanisms. The FETs are first shown to operate as electrical sensors via sensitivity to changes in pH in ionic fluids. The same devices are then demonstrated as highly localized heaters via investigation of experimental heating profiles and comparison to simulation results. These results offer further insight into the heating mechanism and help determine the spatial resolution of the technique. Two important biosensor platform applications spanning different temperature ranges are then demonstrated: a localized heat-mediated DNA exchange reaction and a method for dense selective functionalization of probe molecules via the heat catalyzed complete desorption and reattachment of chemical functionalization to the transistor surfaces. Our results show that the use of silicon transistors can be extended beyond electrical switching and field-effect sensing to performing localized temperature controlled chemical reactions on the transistor itself.


Asunto(s)
Calor , Silicio/química , Transistores Electrónicos , Catálisis , Microscopía Electrónica de Rastreo , Propiedades de Superficie
19.
Artículo en Inglés | MEDLINE | ID: mdl-20178910

RESUMEN

Finite element method (FEM) is used for transient dynamic analysis of capacitive micromachined ultrasonic transducers (CMUT) and is particularly useful when the membranes are driven in the nonlinear regime. One major disadvantage of FEM is the excessive time required for simulation. Harmonic balance (HB) analysis, on the other hand, provides an accurate estimate of the steady-state response of nonlinear circuits very quickly. It is common to use Mason's equivalent circuit to model the mechanical section of CMUT. However, it is not appropriate to terminate Mason's mechanical LC section by a rigid piston's radiation impedance, especially for an immersed CMUT. We studied the membrane behavior using a transient FEM analysis and found out that for a wide range of harmonics around the series resonance, the membrane displacement can be modeled as a clamped radiator. We considered the root mean square of the velocity distribution on the membrane surface as the circuit variable rather than the average velocity. With this definition, the kinetic energy of the membrane mass is the same as that in the model. We derived the force and current equations for a clamped radiator and implemented them using a commercial HB simulator. We observed much better agreement between FEM and the proposed equivalent model, compared with the conventional model.


Asunto(s)
Dinámicas no Lineales , Transductores , Ultrasonido , Análisis de Elementos Finitos , Microtecnología/instrumentación
20.
Pathol Res Pract ; 206(2): 88-92, 2010 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-19959297

RESUMEN

Tumor budding is recognized as an adverse prognostic factor for a few carcinoma types. We evaluated the importance of this finding in 64 laryngeal carcinoma patients treated with surgery and radiotheraphy, with a median follow up of 53 (6-181) months. Budding was determined by re-evaluating hematoxylin-eosin (H&E) stained tumor sections, and classified as mild, moderate, and marked. Budding was not identified in 14 (21.88%) cases. Mild, moderate, and marked budding was observed in 21 (32.81%), 15 (23.44%), and 14 (21.88%) cases, respectively. Only when cases with marked budding were compared with the others, statistically significant results were obtained. In patients with and without marked budding, local disease-free survival, metastatic disease-free survival, and overall survival were 71% and 97% (p=0.72), 77% and 93% (p=0.038), and 77% and 75% (p=0.71), respectively. Marked budding was identified as a prognostic factor by univariate analysis for distant metastasis-free survival. Multi-variate analysis, by which well-recognized prognostic histopathologic parameters were evaluated, revealed that only the number of metastatic lymph nodes and budding were significantly associated with distant metastasis (p=0.02 and p=0.044), respectively. These results suggest that budding might be a valuable prognostic factor, particularly for distant metastasis in laryngeal carcinomas.


Asunto(s)
Carcinoma/patología , Neoplasias Laríngeas/patología , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma/mortalidad , Supervivencia sin Enfermedad , Humanos , Estimación de Kaplan-Meier , Neoplasias Laríngeas/mortalidad , Metástasis Linfática/patología , Persona de Mediana Edad , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Pronóstico
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