Se proporcionó financiación de las Sociedades Americanas e Internacionales de Biomecánica para este estudio.

<ol>
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N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomechanics+IX-B.">Biomechanics IX-B.</a> Human Kinetics. , (1985).</li><li>Challis, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Precision+of+the+Estimation+of+Human+Limb+Inertial+Parameters.">Precision of the Estimation of Human Limb Inertial Parameters.</a> Journal of Applied Biomechanics. 15, 418-428 (1999).</li><li>Challis, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accuracy+of+Human+Limb+Moment+of+Inertia+Estimations+and+Their+Influence+on+Resultant+Joint+Moments.">Accuracy of Human Limb Moment of Inertia Estimations and Their Influence on Resultant Joint Moments.</a> Journal of Applied Biomechanics. 12, 517-530 (1996).</li><li>Challis, J. H., Kerwin, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+the+uncertainties+in+resultant+joint+moments+computed+in+a+dynamic+activity.">Quantification of the uncertainties in resultant joint moments computed in a dynamic activity.</a> J Sports Sci. 14, 219-231 (1996).</li><li>Hunter, J. P., Marshall, R. N., McNair, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Segment-interaction+analysis+of+the+stance+limb+in+sprint+running.">Segment-interaction analysis of the stance limb in sprint running.</a> J Biomech. 37, 1439-1446 (2004).</li><li>Lin-Chan, S. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effects+of+added+prosthetic+mass+on+physiologic+responses+and+stride+frequency+during+multiple+speeds+of+walking+in+persons+with+transtibial+amputation.">The effects of added prosthetic mass on physiologic responses and stride frequency during multiple speeds of walking in persons with transtibial amputation.</a> Arch Phys Med Rehabil. 84, 1865-1871 (2003).</li><li>Mattes, S. J., Martin, P. E., Royer, T. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Walking+symmetry+and+energy+cost+in+persons+with+unilateral+transtibial+amputations:+matching+prosthetic+and+intact+limb+inertial+properties.">Walking symmetry and energy cost in persons with unilateral transtibial amputations: matching prosthetic and intact limb inertial properties.</a> Arch Phys Med Rehabil. 81, 561-568 (2000).</li><li>Smith, J. D., Martin, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Short+and+longer+term+changes+in+amputee+walking+patterns+due+to+increased+prosthesis+inertia.">Short and longer term changes in amputee walking patterns due to increased prosthesis inertia.</a> J Prosthet Orthot. 23, 114-123 (2011).</li><li>Smith, J. D., Martin, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+prosthetic+mass+distribution+on+metabolic+costs+and+walking+symmetry.">Effects of prosthetic mass distribution on metabolic costs and walking symmetry.</a> J Appl Biomech. 29, 317-328 (2013).</li><li>Czerniecki, J. M., Gitter, A., Munro, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Joint+moment+and+muscle+power+output+characteristics+of+below+knee+amputees+during+running:+the+influence+of+energy+storing+prosthetic+feet.">Joint moment and muscle power output characteristics of below knee amputees during running: the influence of energy storing prosthetic feet.</a> J Biomech. 24, 63-75 (1991).</li><li>Miller, D. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resultant+lower+extremity+joint+moments+in+below-knee+amputees+during+running+stance.">Resultant lower extremity joint moments in below-knee amputees during running stance.</a> J Biomech. 20, 529-541 (1987).</li><li>Vanicek, N., Strike, S., McNaughton, L., Polman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gait+patterns+in+transtibial+amputee+fallers+vs.+non-fallers:+Biomechanical+differences+during+level+walking.">Gait patterns in transtibial amputee fallers vs. non-fallers: Biomechanical differences during level walking.</a> Gait &amp; Posture. 29, 415-420 (2009).</li><li>Royer, T., Koenig, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Joint+loading+and+bone+mineral+density+in+persons+with+unilateral,+trans-tibial+amputation.">Joint loading and bone mineral density in persons with unilateral, trans-tibial amputation.</a> Clin Biomech. 20, 1119-1125 (2005).</li><li>Underwood, H. 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Los autores declaran que no tienen intereses financieros en competencia.

Para cuantificar las fuerzas y momentos conjuntas resultantes durante el movimiento, se necesita un modelo de la dinámica inversa del sistema de interés cuando se trabaja con datos empíricos. Para la biomecánica de las extremidades inferiores, los modelos de dinámica inversa típicamente representan la pata, el codillo, y el muslo como cuerpos rígidos. De entrada para estos modelos provienen de tres fuentes principales: a) la cinemática de movimiento, b) las fuerzas de reacción del suelo, y c) antropométricos del segmento y propiedades inerciales. Los datos de movimiento se recogen con una variedad de sistemas de análisis de movimiento, pero todos los sistemas esencialmente proporcionan la cinemática básicas del movimiento (posición, velocidad y aceleración). Fuerzas de reacción del suelo se recogen con una plataforma de fuerza y ​​proporcionan las fuerzas de contacto que actúan sobre los pies. Antropometría son mediciones tomadas directamente de la carrocería con los gobernantes, cintas flexibles, y / o pinzas. Estas mediciones antropométricas se utilizan para estimar las propiedades inerciales de los segmentos corporales utilizados en el dinámicamente inversacs analiza. Propiedades inerciales incluyen la masa, centro de masa (COM) de ubicación y el momento de inercia (MOI) de la serie de sesiones con respecto a un eje que pasa por el COM segmento o el extremo proximal o articulación distal. Metodologías y equipos utilizados para la recogida de los datos de movimiento y la fuerza de reacción del suelo son similares entre los grupos de investigación, pero las estimaciones de inercia de los segmentos corporales pueden variar ampliamente entre los investigadores en función del método que el investigador elige para estimar estas propiedades inerciales. Diversas técnicas disponibles para la estimación de las propiedades inerciales de un segmento del cuerpo humano completamente intacta incluyen: 1) las ecuaciones de regresión basadas en datos de cadáver 1-5, 2) técnicas de modelos matemáticos (es decir, modelos geométricos) 6,7, y 3) de exploración y proyección de imagen 8-15. Muchas de estas técnicas requieren mediciones directas del cuerpo, pero se ha demostrado previamente que, independientemente del método de estimación se utiliza, la precisión de segmento corporalestimaciones inerciales Ment basados ​​en estos métodos es alta 16. También se ha demostrado que los errores en las estimaciones de las propiedades inerciales de los segmentos del cuerpo intactos tienen un impacto mínimo en las magnitudes de los momentos conjuntos resultantes durante la marcha 17,18. Momentos conjuntos están influenciados en mayor medida por las fuerzas de reacción del suelo, centro de los lugares de presión, momento longitudes de brazo, y la cinemática del segmento 17-19. Por lo tanto, no es sorprendente que los métodos para estimar las propiedades de inercia de los segmentos corporales varían ampliamente a través de la literatura utilizando las personas sin discapacidad como participantes en la investigación, dado que los pequeños errores en estos cálculos es probable que tengan poco impacto en los resultados del estudio. Muchas de estas estimaciones de inercia para un segmento del cuerpo intacto a menudo se utilizan para estimar las propiedades inerciales de prótesis para amputados de extremidades inferiores. Modernos prótesis de miembro inferior se fabrican utilizando materiales ligeros resultadoing en las prótesis que son mucho más ligeros que los miembros que reemplazan. Esto resulta en una asimetría inercial entre la prótesis y la extremidad intacta. En comparación con un vástago típica intacto y el pie, la masa de una prótesis debajo de la rodilla y la extremidad residual es de aproximadamente 35% menos y tiene un centro de masa situado a aproximadamente 35% más cerca de la articulación de la rodilla 20-23. La masa inferior y distribución de la masa más proximal de la prótesis también produce una (~ 60%) mucho menor momento de inercia con respecto a la articulación de la rodilla para la prótesis en comparación con la de la espiga intacta y el pie. Aunque los investigadores 24,25 han sugerido previamente que el uso de estimaciones de inercia intactas para la prótesis tiene poco efecto sobre las estimaciones cinéticos conjuntas, estas comparaciones se centraron en momentos conjuntos resultantes durante la fase de apoyo de la marcha, donde la fuerza de reacción del suelo domina el momento producido en la conjunta. Durante swing, donde las fuerzas de reacción del suelo no están presentes, ella reducción de las propiedades inerciales de la prótesis son más propensos a influir en las estimaciones de momentos conjuntos resultantes. Teniendo en cuenta que algunos investigadores, por ejemplo, 26-32 utilizan intactas las propiedades de inercia segmento para representar prótesis propiedades inerciales y otros, por ejemplo 21 a 23 propiedades inerciales de prótesis estimación directa, es importante para comprender el impacto de los métodos elegidos para la estimación de las propiedades inerciales de la prótesis . Reducir al mínimo el tiempo necesario para medir las propiedades inerciales de la prótesis era una consideración importante en el desarrollo de nuestra técnica. En la técnica que aquí se presenta la prótesis permanece completamente intacto para todas las medidas para reducir los tiempos de medición y evitar cualquier veces adicionales asociados con la realineación de la prótesis después de la medición. Por lo tanto, el propósito de este estudio era doble: 1) demostrar una técnica que se puede utilizar directamente para estimar las propiedades inerciales de ABprótesis elow rodilla, y 2) contrastar los efectos de la técnica propuesta y la del uso de las extremidades intactas las propiedades inerciales en estimaciones cinéticos conjuntas durante la marcha en amputados tibiales, unilaterales. Se planteó la hipótesis que las magnitudes cinéticas conjuntos son más grandes cuando las propiedades inerciales de la espiga intacta y el pie se utilizan como las estimaciones de inercia para la prótesis en comparación con las mediciones directas de las propiedades inerciales de prótesis.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">Oscillation Rack &#38; Reaction Board</td>
			<td style="width:144px;">Custom Built</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Outer cage made from 80/20 aluminum, inner cage from various thicknesses of solid of aluminum.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Laboratory scale</td>
			<td style="width:144px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">NI LabView</td>
			<td style="width:144px;">National Instruments</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Software for recording TTL pulses from infrared photocell.</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">BNC-1050</td>
			<td style="width:144px;">National Instruments</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">BNC Breakout box with direct pin connections to the data acquisition card</td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">MATLAB</td>
			<td style="width:144px;">Mathworks Inc.</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Software for processing oscillation and reaction board data to predict inertial properties of prosthesis.</td>
		</tr>
	</tbody>
</table>

oscillation and reaction board techniques for estimating inertial properties of a below-knee prosthesis

El propósito de este estudio fue doble: 1) demostrar una técnica que se puede utilizar para estimar directamente las propiedades inerciales de una prótesis debajo de la rodilla, y 2) contrastar los efectos de la técnica propuesta y la del uso de las extremidades intactas las propiedades inerciales en cálculos cinéticos conjuntas durante la marcha en amputados tibiales, unilaterales. Un sistema de oscilación y tabla reacción fue validado y demostrado ser fiable en la medición de las propiedades de inercia de sólidos geométricos conocidos. Cuando se utilizaron las mediciones directas de carácter inercial de la prótesis en la dinámica inversa de modelado de la extremidad inferior en comparación con las estimaciones de inercia sobre la base de un vástago intacta y el pie, la cinética de las articulaciones de la cadera y la rodilla fueron significativamente menores durante la fase de balanceo de la marcha. Las diferencias en la cinética conjuntas durante postura, sin embargo, fueron menores que los observados durante el swing. Por lo tanto, los investigadores se centran en la fase de balanceo de la marcha deben considerar el impacto de prostheses propiedad de inercia estimaciones sobre los resultados del estudio. Por postura, ya sea uno de los dos modelos de inercia investigados en nuestro estudio probablemente conduciría a resultados similares con una evaluación dinámica inversa.

Propiedades inerciales de la pierna de prótesis distal a la rodilla fueron inferiores a los de la pierna intacta (Tabla 1). Como promedio entre los participantes, la masa lado protésica era 39% menos, momento de inercia alrededor de un eje transversal a través de la rodilla era 52% menos, y el centro de ubicación de la masa era 24% más cerca de la rodilla en comparación con los valores para la pierna intacta. <table border="1" cellpadding="0" cellspacing="0" fo:keep-together.within-page="always" width="553"><tbody><tr><td> Sujeto </td><td> Intacto * Masa (kg) </td><td> Pros † Masa (kg) </td><td> Est. Diferencia de masa (kg) </td><td> ‡ Iknee intacta (kg · m 2) </td><td> Pros Iknee (kg · m 2) </td><td> CM intacta debajo de la articulación de la rodilla (m) </td><td> Pros cm por debajo de la articulación de la rodilla (m) </td></tr><tr><td> La </td><td> 6.03 </td><td> 4.27 </td><td> 1.76 </td><td> 0.604 </td><td> 0.325 </td><td> 0.268 </td><td> 0.215 </td></tr><tr><td> B </td><td> 6.07 </td><td> 3.39 </td><td> 2.68 </td><td> 0.400 </td><td> 0.196 </td><td> 0.215 </td><td> 0.177 </td></tr><tr><td> C </td><td> 5.80 </td><td> 3.12 </td><td> 2.68 </td><td> 0.575 </td><td> 0.194 </td><td> 0.264 </td><td> 0.198 </td></tr><tr><td> D </td><td> 5.72 </td><td> 3.17 </td><td> 2.55 </td><td> 0.559 </td><td> 0.317 </td><td> 0.265 </td><td> 0.191 </td></tr><tr><td> E </td><td> 7.14 </td><td> 4.65 </td><td> 2.49 </td><td> 0.742 </td><td> 0.325 </td><td> 0.276 </td><td> 0.200 </td></tr><tr><td> F </td><td> 6.23 </td><td> 4.22 </td><td> 2.01 </td><td> 0.585 </td><td> 0.287 </td><td> 0.260 </td><td> 0.192 </td></tr><tr><td> La media ± STD </td><td> 6,17 ± 0,51 </td><td> 3,80 ± 0,66 </td><td> 2,36 ± 0,38 </td><td> 0,578 ± 0,109 </td><td> 0,274 ± 0,063 </td><td> 0.258 y# 177; 0.022 </td><td> 0,196 ± 0,013 </td></tr></tbody></table> * Intacto se refiere a los valores de la caña intacta combinado y el pie. † Pros se refiere a los valores de la prótesis combinada y muñón. ‡ Momento de inercia alrededor de un eje transversal a través de la rodilla. Tabla 1. Comparación de las propiedades de inercia entre las prótesis e intactos desde la rodilla hacia abajo. Fuerzas conjuntas resultantes (Figura 3) y momentos (Figura 4) en el tobillo, la rodilla y la cadera se vieron afectados por los parámetros inerciales utilizados en el modelo de la dinámica inversa. Específicamente, la cinética de conjuntos se redujeron durante la iniciación de oscilación (~ 65% de ciclo de la marcha) y de terminación de oscilación (~ 95% del ciclo de andar) cuando se usaron medidas directas de la inercia de prótesis en las evaluaciones de la dinámica inversa en comparación con regresiones basados ​​en la anatomía intacta ( <strong&gt; Cuadro 2). Los tamaños del efecto sugieren estas diferencias durante oscilación no eran triviales (≥ 1,0). Además, los valores cinéticos conjuntas aumentaron en promedio un 80% durante el inicio y la terminación de oscilación cuando se usaron estimaciones inerciales intactos en comparación con las mediciones directas de las propiedades inerciales de prótesis. Por lo tanto, cuando se utilizaron las propiedades inerciales de una extremidad intacta para modelar el lado protésico, perfiles cinéticos conjuntos de la parte protésica durante la oscilación se parecían más a los de un miembro intacto (véanse las figuras 3 y 4). Durante postura, se observaron una serie de diferencias estadísticas. El tamaño del efecto más grande de cualquier diferencia en la postura se observó para la cadera anterioposterior fuerza conjunta resultante (ES = 0,86). Aunque este tamaño del efecto es grande y todavía se considera como parte de la postura, se produjo el valor máximo para esta medida durante la posición terminal (~ 52%), o como la rama estaba en transición hacia swing. Los tamaños del efecto para todos los demás significant diferencias observadas durante la posición variaron desde 0,01 hasta 0,41, que se considera pequeños efectos con el mayor de estos valores que se observan en las fuerzas de reacción conjuntos resultantes de la cadera. Aunque no se encontraron diferencias significativas durante el apoyo, estas diferencias cuando se considera en términos de la magnitud de la diferencia (es decir, el tamaño del efecto) podrían llevar a cuestionar el significado de estas diferencias. <img alt="Figura 3" fo:content-width="5in" src="/files/ftp_upload/50977/50977fig3highres.jpg" width="500" /> Figura 3. Fuerzas de reacción conjuntas resultantes del tobillo, rodilla y cadera en el anterioposterior (paneles de la izquierda) y en dirección vertical (paneles de la derecha). Los datos fueron promediados a través de temas para su presentación. La fase de apoyo comienza en 0% del ciclo de andar con el contacto del pie y termina en aproximadamente el 60% del ciclo de la marcha con despegue de los dedos. Oscilación continúa hasta el próximo contacto del pie de tél mismo la pierna al 100% del ciclo de andar. <a href="https://www.jove.com/files/ftp_upload/50977/50977fig3highres.jpg" target="_blank">Haga clic aquí para ver una versión más grande de esta figura.</a> <img alt="Figura 4" fo:content-width="5in" src="/files/ftp_upload/50977/50977fig4highres.jpg" width="500" /> Figura 4. Conjunta momentos resultantes sobre un eje transversal (aka, eje mediolateral) a través del tobillo, la rodilla y la cadera. Los datos fueron promediados a través de temas para su presentación. La fase de apoyo comienza en 0% del ciclo de andar con el contacto del pie y termina en aproximadamente el 60% del ciclo de la marcha con despegue de los dedos. Oscilación continúa hasta el siguiente contacto con el pie de la misma pierna al 100% del ciclo de la marcha. <img alt="Tabla 2" fo:content-width="6in" src="/files/ftp_upload/50977/50977table2.jpg" width="600" /> Tabla 2. Pico reacción conjunta resultantefuerzas y momentos en promedio entre los sujetos y las comparaciones estadísticas entre los dos modelos de inercia de la cinética de las articulaciones del lado protésico Notas:. media de los datos se presentan como media (desviación estándar). % Columna Gait Cycle representa el porcentaje promedio en los temas en los que el valor máximo se produjo para esa variable. P &lt;0,05 consideró significativo.

Watch this Scientific Journal Video about Oscillation and Reaction Board Techniques for Estimating Inertial Properties of a Below-knee Prosthesis at JoVE.com

Oscillation and Reaction Board Techniques for Estimating Inertial Properties of a Below-knee Prosthesis

Se requieren segmentarias del cuerpo inercial para el modelado de la dinámica inversa. Usando una técnica de oscilación y tablero de reacción, propiedades inerciales de prótesis debajo de la rodilla se midieron. El uso de medidas directas de inercia prótesis en el modelo de la dinámica inversa de la pierna protésica resultó en magnitudes más bajas de las fuerzas y momentos conjuntas resultantes.

Oscilación y de la Junta de Reacción técnicas para estimar inerciales propiedades de una prótesis debajo de la rodilla

The purpose of this study was two-fold: 1) demonstrate a technique that can be used to directly estimate the inertial properties of a below-knee ...

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Moment of Inertia

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16.6K vistas.  University of Northern Colorado.  Se requieren segmentarias del cuerpo inercial para el modelado de la dinámica inversa. Usando una técnica de oscilación y tablero de reacción, propiedades inerciales de prótesis debajo de la rodilla se midieron. El uso de medidas directas de inercia prótesis en el modelo de la dinámica inversa de la pierna protésica resultó en magnitudes más bajas de las fuerzas y momentos conjuntas resultantes. 

Video: Oscillation and Reaction Board Techniques for Estimating Inertial Properties of a Below-knee Prosthesis

Measuring the Mechanical Properties of Living Cells Using Atomic Force Microscopy

Mechanical properties of cells and extracellular matrix (ECM) play important roles in many biological processes including stem cell differentiation, tumor formation, and wound healing. Changes in stiffness of cells and ECM are often signs of changes in cell physiology or diseases in tissues. Hence, cell stiffness is an index to evaluate the status of cell cultures. Among the multitude of methods applied to measure the stiffness of cells and tissues, micro-indentation using an Atomic Force Microscope (AFM) provides a way to reliably measure the stiffness of living cells. This method has been widely applied to characterize the micro-scale stiffness for a variety of materials ranging from metal surfaces to soft biological tissues and cells. The basic principle of this method is to indent a cell with an AFM tip of selected geometry and measure the applied force from the bending of the AFM cantilever. Fitting the force-indentation curve to the Hertz model for the corresponding tip geometry can give quantitative measurements of material stiffness. This paper demonstrates the procedure to characterize the stiffness of living cells using AFM. Key steps including the process of AFM calibration, force-curve acquisition, and data analysis using a MATLAB routine are demonstrated. Limitations of this method are also discussed.

This paper demonstrates a protocol to characterize the mechanical properties of living cells by means of microindentation using an Atomic Force Microscope (AFM).

Medición de las propiedades mecánicas de las células vivas mediante microscopía de fuerza atómica

Mechanical  properties of cells and extracellular matrix (ECM) play important roles in many  biological processes including stem cell differentiation, ...

Investigación

Bioingeniería

Engineering Platform and Experimental Protocol for Design and Evaluation of a Neurally-controlled Powered Transfemoral Prosthesis

To enable intuitive operation of powered artificial legs, an interface between user and prosthesis that can recognize the user's movement intent is desired. A novel neural-machine interface (NMI) based on neuromuscular-mechanical fusion developed in our previous study has demonstrated a great potential to accurately identify the intended movement of transfemoral amputees. However, this interface has not yet been integrated with a powered prosthetic leg for true neural control. This study aimed to report (1) a flexible platform to implement and optimize neural control of powered lower limb prosthesis and (2) an experimental setup and protocol to evaluate neural prosthesis control on patients with lower limb amputations. First a platform based on a PC and a visual programming environment were developed to implement the prosthesis control algorithms, including NMI training algorithm, NMI online testing algorithm, and intrinsic control algorithm. To demonstrate the function of this platform, in this study the NMI based on neuromuscular-mechanical fusion was hierarchically integrated with intrinsic control of a prototypical transfemoral prosthesis. One patient with a unilateral transfemoral amputation was recruited to evaluate our implemented neural controller when performing activities, such as standing, level-ground walking, ramp ascent, and ramp descent continuously in the laboratory. A novel experimental setup and protocol were developed in order to test the new prosthesis control safely and efficiently. The presented proof-of-concept platform and experimental setup and protocol could aid the future development and application of neurally-controlled powered artificial legs.

Neural-machine interfaces (NMI) have been developed to identify the user's locomotion mode. These NMIs are potentially useful for neural control of powered artificial legs, but have not been fully demonstrated. This paper presented (1) our designed engineering platform for easy implementation and development of neural control for powered lower limb prostheses and (2) an experimental setup and protocol in a laboratory environment to evaluate neurally-controlled artificial legs on patients with lower limb amputations safely and efficiently.

Plataforma Ingeniería y Protocolo Experimental para el Diseño y Evaluación de una controlada por Neuralmente Powered transfemoral de prótesis

To enable intuitive operation of powered artificial legs, an interface between user and prosthesis that can recognize the user's movement intent is ...

In Situ Mapping of the Mechanical Properties of Biofilms by Particle-tracking Microrheology

Bacterial cells are able to form surface-attached biofilm communities known as biofilms by encasing themselves in extracellular polymeric substances (EPS). The EPS serves as a physical and protective scaffold that houses the bacterial cells and consists of a variety of materials that includes proteins, exopolysaccharides and DNA. The composition of the EPS may change, which remodels the mechanic properties of the biofilm to further develop or support alternative biofilm structures, such as streamers, as a response to environmental cues. Despite this, there are little quantitative descriptions on how EPS components contribute to the mechanical properties and function of biofilms. Rheology, the study of the flow of matter, is of particular relevance to biofilms as many biofilms grow in flow conditions and are constantly exposed to shear stress. It also provides measurement and insight on the spreading of the biofilm on a surface. Here, particle-tracking microrheology is used to examine the viscoelasticity and effective crosslinking roles of different matrix components in various parts of the biofilm during development. This approach allows researchers to measure mechanic properties of biofilms at the micro-scale, which might provide useful information for controlling and engineering biofilms.

In Situ Mapping of the Mechanical Properties of Biofilms by Particle-tracking Microrheology

Particle-tracking microrheology investigates the viscoelasticity of materials. Here, the technique is used to determine the viscoelasticity, creep compliance and effective crosslinking roles of different matrix components of a bacterial biofilm. The matrix consists of polymeric substances secreted by the bacteria and its components determine biofilm structure and mechanical properties.

En Mapping in situ de las propiedades mecánicas de biopelículas por partículas de seguimiento Microrheology

Bacterial cells are able to form surface-attached biofilm communities known as biofilms by encasing themselves in extracellular polymeric substances ...

Techniques for the Evolution of Robust Pentose-fermenting Yeast for Bioconversion of Lignocellulose to Ethanol

Lignocellulosic biomass is an abundant, renewable feedstock useful for production of fuel-grade ethanol and other bio-products. Pretreatment and enzyme saccharification processes release sugars that can be fermented by yeast. Traditional industrial yeasts do not ferment xylose (comprising up to 40% of plant sugars) and are not able to function in concentrated hydrolyzates. Concentrated hydrolyzates are needed to support economical ethanol recovery, but they are laden with toxic byproducts generated during pretreatment. While detoxification methods can render hydrolyzates fermentable, they are costly and generate waste disposal liabilities. Here, adaptive evolution and isolation techniques are described and demonstrated to yield derivatives of the native Scheffersomyces stipitis strain NRRL Y-7124 that are able to efficiently convert hydrolyzates to economically recoverable ethanol despite adverse culture conditions. Improved individuals are enriched in an evolving population using multiple selection pressures reliant on natural genetic diversity of the S. stipitis population and mutations induced by exposures to two diverse hydrolyzates, ethanol or UV radiation. Final evolution cultures are dilution plated to harvest predominant isolates, while intermediate populations, frozen in glycerol at various stages of evolution, are enriched on selective media using appropriate stress gradients to recover most promising isolates through dilution plating. Isolates are screened on various hydrolyzate types and ranked using a novel procedure involving dimensionless relative performance index (RPI) transformations of the xylose uptake rate and ethanol yield data. Using the RPI statistical parameter, an overall relative performance average is calculated to rank isolates based on multiple factors, including culture conditions (varying in nutrients and inhibitors) and kinetic characteristics. Through application of these techniques, derivatives of the parent strain had the following improved features in enzyme saccharified hydrolyzates at pH 5-6: reduced initial lag phase preceding growth, reduced diauxic lag during glucose-xylose transition, significantly enhanced fermentation rates, improved ethanol tolerance and accumulation to 40 g/L.

Adaptive evolution and isolation techniques are described and demonstrated to yield derivatives of Scheffersomyces stipitis strain NRRL Y-7124 that are able to rapidly consume hexose and pentose mixed sugars in enzyme saccharified undetoxified hydrolyzates and to accumulate over 40 g/L ethanol.

Las técnicas para la Evolución de la robusta levaduras que fermentan la pentosa para la bioconversión de lignocelulosa en etanol

Lignocellulosic biomass is an abundant, renewable feedstock useful for production of fuel-grade ethanol and other bio-products. Pretreatment and enzyme ...

Production of Metal Nanoparticles by Pulsed Laser-ablation in Liquids: A Tool for Studying the Antibacterial Properties of Nanoparticles

The emergence of multidrug-resistant bacteria is a global clinical concern leading some to speculate about our return to a "pre-antibiotics" era of medicine. In addition to efforts to identify novel small-molecule antimicrobial drugs, there has been great interest in the use of metal nanoparticles as coatings for medical devices, wound dressings, and consumer packaging, due to their antimicrobial properties. The wide variety of methods available for nanoparticle synthesis results in a broad spectrum of chemical and physical properties which can affect antibacterial efficacy. This manuscript describes the pulsed laser-ablation in liquids (PLAL) method to create nanoparticles. This approach allows for the fine tuning of nanoparticle size, composition, and stability using post-irradiation methods as well as the addition of surfactants or volume excluders. By controlling particle size and composition, a large range of physical and chemical properties of metal nanoparticles can be explored which may contribute to their antimicrobial efficacy thereby opening new avenues for antibacterial development.

The antimicrobial properties of metals such as copper and silver have been recognized for centuries. This protocol describes pulsed laser-ablation in liquids, a method of synthesizing metal nanoparticles that provides the ability to fine tune the properties of these nanoparticles to optimize their antimicrobial effects.

Producción de nanopartículas metálicas por ablación por láser pulsado en líquidos: una herramienta para estudiar las propiedades antibacterianas de las nanopartículas

The emergence of multidrug-resistant bacteria is a global clinical concern leading some to speculate about our return to a "pre-antibiotics" era of ...

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and thus achieving stable water permeability through membranes over time. Here, we report a facile method to prepare hydrogels based on zwitterions for membrane applications. Freestanding films can be prepared from sulfobetaine methacrylate (SBMA) with a crosslinker of poly(ethylene glycol) diacrylate (PEGDA) via photopolymerization. The hydrogels can also be prepared by impregnation into hydrophobic porous supports to enhance the mechanical strength. These films can be characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine the degree of conversion of the (meth)acrylate groups, using goniometers for hydrophilicity and differential scanning calorimetry (DSC) for polymer chain dynamics. We also report protocols to determine the water permeability in dead-end filtration systems and the effect of foulants (bovine serum albumin, BSA) on membrane performance.

This paper reports practical methods to prepare hydrogels in freestanding films and impregnated membranes and to characterize their physical properties, including water transport properties.

Síntesis de hidrogeles con propiedades antiincrustantes como membranas de purificación de agua

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and ...

Semiautomated Longitudinal Microcomputed Tomography-based Quantitative Structural Analysis of a Nude Rat Osteoporosis-related Vertebral Fracture Model

Osteoporosis-related vertebral compression fractures (OVCFs) are a common and clinically unmet need with increasing prevalence as the world population ages. Animal OVCF models are essential to the preclinical development of translational tissue engineering strategies. While a number of models currently exist, this protocol describes an optimized method for inducing multiple highly reproducible vertebral defects in a single nude rat. A novel longitudinal semiautomated microcomputed tomography (&#181;CT)-based quantitative structural analysis of the vertebral defects is also detailed. Briefly, rats were imaged at multiple time points post-op. The day 1 scan was reoriented to a standard position, and a standard volume of interest was defined. Subsequent &#181;CT scans of each rat were automatically registered to the day 1 scan so the same volume of interest was then analyzed to assess for new bone formation. This versatile approach can be adapted to a variety of other models where longitudinal imaging-based analysis could benefit from precise 3D semiautomated alignment. Taken together, this protocol describes a readily quantifiable and easily reproducible system for osteoporosis and bone research. The suggested protocol takes 4 months to induce osteoporosis in nude ovariectomized rats and between 2.7 and 4 h to generate, image, and analyze two vertebral defects, depending on tissue size and equipment.

The goal of this protocol is to generate a nude rat osteoporosis-related vertebral compression fracture model that can be longitudinally evaluated in vivo using a semiautomated microcomputed tomography-based quantitative structural analysis.

Semiautomatizado Longitudinal basado en la tomografía Microcomputed cuantitativo análisis estructural de un modelo de rata desnuda fractura Vertebral relacionada con la Osteoporosis

Osteoporosis-related vertebral compression fractures (OVCFs) are a common and clinically unmet need with increasing prevalence as the world population ...

A Millimeter Scale Flexural Testing System for Measuring the Mechanical Properties of Marine Sponge Spicules

Many load bearing biological structures (LBBSs)&#8212;such as feather rachises and spicules&#8212;are small (&#60;1 mm) but not microscopic. Measuring the flexural behavior of these LBBSs is important for understanding the origins of their remarkable mechanical functions.
We describe a protocol for performing three-point bending tests using a custom-built mechanical testing device that can measure forces ranging from 10-5 to 101 N and displacements ranging from 10-7 to 10-2 m. The primary advantage of this mechanical testing device is that the force and displacement capacities can be easily adjusted for different LBBSs. The device&#39;s operating principle is similar to that of an atomic force microscope. Namely, force is applied to the LBBS by a load point that is attached to the end of a cantilever. The load point displacement is measured by a fiber optic displacement sensor and converted into a force using the measured cantilever stiffness. The device&#39;s force range can be adjusted by using cantilevers of different stiffnesses.
The device&#39;s capabilities are demonstrated by performing three-point bending tests on the skeletal elements of the marine sponge Euplectella aspergillum. The skeletal elements&#8212;known as spicules&#8212;are silica fibers that are approximately 50 &#181;m in diameter. We describe the procedures for calibrating the mechanical testing device, mounting the spicules on a three-point bending fixture with a &#8776;1.3 mm span, and performing a bending test. The force applied to the spicule and its deflection at the location of the applied force are measured.

We present a protocol for performing three-point bending tests on sub-millimeter scale fibers using a custom-built mechanical testing device. The device can measure forces ranging from 20 &#181;N up to 10 N and can therefore accommodate a variety of fiber sizes.

Un milímetro a la flexión prueba sistema de la escala para medir las propiedades mecánicas de espículas de esponja marina

Many load bearing biological structures (LBBSs)&#8212;such as feather rachises and spicules&#8212;are small (&#60;1 mm) but not microscopic. Measuring the ...

Synthesis of Multi-walled Carbon Nanotubes Modified with Silver Nanoparticles and Evaluation of Their Antibacterial Activities and Cytotoxic Properties

In this study, multi-walled carbon nanotubes (MWCNTs) were treated with an aqueous sulfuric acid solution to form an oxygen-based functional group. Silver MWCNTs were prepared by the reductive deposition of silver from an aqueous solution of AgNO3 on the oxidized MWCNTs. Given the unique color of the CNTs, it was not possible to apply them to the minimum inhibitory concentration or mitochondrial toxicity assays to evaluate the toxicity and antibacterial properties, since they would interfere with the assays. The inhibition zone and minimum bactericidal concentration for the Ag-MWCNTs were measured and Live/Dead and Trypan Blue assays were used to measure the toxicity and antibacterial properties without interfering with the color of the CNTs.

In this study, antimicrobial nanomaterials were synthesized by acidic oxidation of multiwalled carbon nanotubes and subsequent reductive deposition of silver nanoparticles. Antimicrobial activity and cytotoxicity tests were performed with the as-prepared nanomaterials.

Síntesis de nanotubos de carbono multipared modificados con nanopartículas de plata y la evaluación de sus actividades antibacterianas y propiedades citotóxicas

In this study, multi-walled carbon nanotubes (MWCNTs) were treated with an aqueous sulfuric acid solution to form an oxygen-based functional group. Silver ...

3D Printing of In Vitro Hydrogel Microcarriers by Alternating Viscous-Inertial Force Jetting

Microcarriers are beads with a diameter of 60-250 &#181;m and a large specific surface area, which are commonly used as carriers for large-scale cell cultures. Microcarrier culture technology has become one of the main techniques in cytological research and is commonly used in the field of large-scale cell expansion. Microcarriers have also been shown to play an increasingly important role in in vitro tissue engineering construction and clinical drug screening. Current methods for preparing microcarriers include microfluidic chips and inkjet printing, which often rely on complex flow channel design, an incompatible two-phase interface, and a fixed nozzle shape. These methods face the challenges of complex nozzle processing, inconvenient nozzle changes, and excessive extrusion forces when applied to multiple bioink. In this study, a 3D printing technique, called alternating viscous-inertial force jetting, was applied to enable the construction of hydrogel microcarriers with a diameter of 100-300 &#181;m. Cells were subsequently seeded on microcarriers to form tissue engineering modules. Compared to existing methods, this method offers a free nozzle tip diameter, flexible nozzle switching, free control of printing parameters, and mild printing conditions for a wide range of bioactive materials.

3D Printing of In Vitro Hydrogel Microcarriers by Alternating Viscous-Inertial Force Jetting

Presented here is a mild 3D printing technique driven by alternating viscous-inertial forces to enable the construction of hydrogel microcarriers. Homemade nozzles offer flexibility, allowing easy replacement for different materials and diameters. Cell binding microcarriers with a diameter of 50-500 &#181;m can be obtained and collected for further culturing.

Impresión 3D de microportadores de hidrogel in vitro mediante chorro de fuerza viscoso-inercial alternado

Microcarriers are beads with a diameter of 60-250 &#181;m and a large specific surface area, which are commonly used as carriers for large-scale cell ...