Funding from the American and International Societies of Biomechanics was provided for this study.

<ol>
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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. 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The authors declare that they have no competing financial interests.

Die resultierende Gelenkkräfte und Momente bei der Bewegung zu quantifizieren, wird eine inverse Dynamikmodell des Systems von Interesse erforderlich, wenn mit empirischen Daten. Für untere Extremität Biomechanik, inverse Dynamikmodelle stellen in der Regel den Fuß, Schaft und Oberschenkel als starre Körper. Eingang für diese Modelle stammen aus drei Hauptquellen: a) Bewegungskinematik, b) Bodenreaktionskräfte, und c) Segment Anthropometrie und Trägheitseigenschaften. Bewegungsdaten mit einer Vielzahl von Bewegungsanalysesystemen gesammelt, aber alle Systeme im wesentlichen die Grund Kinematik der Bewegung (Position, Geschwindigkeit und Beschleunigung). Bodenreaktionskräfte sind mit einer Kraftmessplatte gesammelt und bieten die an den Füßen wirkenden Kontaktkräfte. Anthropometrie sind Messungen direkt aus dem Körper mit Herrschern, flexible Bänder und / oder Bremssättel gemacht. Die anthropometrischen Messungen verwendet werden, um die Trägheitseigenschaften der Körpersegmente im umgekehrten dynamisch verwendet schätzencs-Analysen. Trägheitseigenschaften umfassen die Masse, Schwerpunkt (COM) Lage und Trägheitsmoment (MOI) des Segments relativ zu einer Achse durch das Segment COM oder dem proximalen oder distalen Gelenk. Methoden und Geräte zum Sammeln Bewegung und Bodenreaktionskraft-Daten verwendet werden, sind ähnlich unter den Forschungsgruppen, aber Trägheits Schätzungen der Körpersegmente kann weit unter den Forschern je nachdem, welche Methode der Forscher wählt für die Schätzung dieser Trägheitseigenschaften variieren. Verschiedene Techniken zur Schätzung der Trägheitseigenschaften eines voll intakten menschlichen Körpersegment verfügbar sind: 1) Regressionsgleichungen, basierend auf Daten kadaver 1-5, 2) mathematische Modelle (dh geometrische Modelle) 6,7, und 3) Scannen und Imaging-Techniken 15.08. Viele dieser Techniken erfordern die direkte Messung von dem Körper, aber es wurde zuvor gezeigt, dass unabhängig von der Schätzverfahren verwendet werden, die Genauigkeit der Körpersegmentement Trägheits Schätzungen auf der Grundlage dieser Methoden ist hoch 16. Es ist auch gezeigt worden, daß Fehler in den Schätzungen der Trägheitseigenschaften von intakten Körpersegmente haben minimale Auswirkungen auf die Größen der resultierenden gemeinsamen Momenten während des Gehens 17,18. Gemeinsame Momente werden in einem größeren Ausmaß von Bodenreaktionskräfte, Druckzentrum Standorten Moment Armlängen und Segment Kinematik 17-19 beeinflusst. Daher ist es nicht verwunderlich, dass Methoden zur Schätzung Trägheitseigenschaften von Körpersegmente bei der Verwendung von nicht behinderten Personen als Forschungsteilnehmer gegeben, dass kleine Fehler in den Schätzungen sind wahrscheinlich wenig Einfluss auf die Ergebnisse der Studie haben große Unterschiede in der Literatur. Viele dieser Trägheits Schätzungen für eine völlig intakte Körpersegment sind oft für die Schätzung der Trägheitseigenschaften von Prothesen für die unteren Extremität Amputationen verwendet. Moderne Beinprothesen werden mit leichten Materialien hergestellt resulting in Prothesen, die viel leichter als die Glieder, die sie ersetzen sind. Dies führt zu einer Asymmetrie zwischen dem Trägheits Prothese und intakten Extremität. Verglichen mit einer typischen intakten Schaft und Fuß, der Masse eines Unterschenkelprothese und Restglied ist etwa 35% kleiner ist und eine Massenzentrum liegt etwa 35% näher zum Kniegelenk 20-23. Die geringere Masse und proximalen Massenverteilung der Prothese erzeugt auch eine viel geringere (~ 60%) Trägheitsmoment relativ zu dem Kniegelenk für die Prothese im Vergleich zu derjenigen der intakten Schaft und Fuß. Obwohl Forscher 24,25 vorher vorgeschlagen, dass unter Verwendung von intakten Trägheits Schätzungen für die Prothese haben wenig Einfluss auf gemeinsame kinetische Schätzungen, diese Vergleiche auf resultierende gemeinsame Momente während der Standphase des Gehens, wo dominiert die Bodenreaktionskraft den Zeitpunkt der erzeugte konzentriert Gelenk. Während Schaukel, wo Bodenreaktionskräfte nicht vorhanden sind, diereduzierte Trägheitseigenschaften der Prothese eher Schätzungen der resultierende gemeinsame Momente zu beeinflussen. Da einige Forscher zB, 26-32 nutzen intakten Segment Trägheitseigenschaften zu Prothese Trägheitseigenschaften darstellen und andere z. B. 21-23 Schätzung Prothese Trägheitseigenschaften direkt, es ist wichtig, die Auswirkungen der für die Schätzung der Trägheitseigenschaften der Prothese gewählten Methoden verstehen . Minimierung der Zeit für die Messung Trägheitseigenschaften der Prothese erforderlich war eine wichtige Überlegung bei der Entwicklung der Technik. In der hier vorgestellten Technik bleibt die Prothese vollständig erhalten für alle Messungen zu Messzeiten reduzieren und vermeiden zusätzliche Male mit der Neuausrichtung der Prothese nach der Messung verbunden. So ist der Zweck dieser Studie war zweifach: 1) zeigen, eine Technik, um die Trägheitseigenschaften ab schätzen direkt verwendet werden könnenelow-Knieprothese, und 2) die Auswirkungen der Kontrast der vorgeschlagenen Technik und der Verwendung von intakten Gliedmaßen Trägheitseigenschaften gemeinsame kinetische Schätzungen während des Gehens in einseitigen, Unterschenkelamputierte. Es wurde vermutet, dass die gemeinsame kinetische Größen sind größer, wenn Trägheitseigenschaften des intakten Schaft und Fuß sind als die Trägheits Schätzungen für die Prothese im Vergleich zu direkten Messungen der Prothesenträgheitseigenschaften verwendet.

<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

Der Zweck dieser Studie war zweifach: 1) zeigen eine Technik, die verwendet werden kann, um direkt eine Schätzung der Trägheitseigenschaften einer Unterschenkelprothese, und 2) die Kontrasteffekte der vorgeschlagenen Technik und der Verwendung von intakten Extremität Trägheitseigenschaften gemeinsame kinetische Schätzungen während des Gehens in einseitigen, Unterschenkelamputierte. Eine Schwingungs und Reaktions Board-System wurde validiert und als zuverlässig erwiesen, wenn die Messung Trägheitseigenschaften von bekannten geometrischen Festkörper. Bei direkten Messungen der Trägheitseigenschaften der Prothese wurden in inverse Dynamik Modellierung der unteren Extremität verwendet, verglichen mit Trägheits Schätzungen auf der Grundlage einer intakten Schaft und Fuß, waren gemeinsame Kinetik an der Hüfte und Knie deutlich niedriger während der Schwungphase des Gehens. Unterschiede in der gemeinsamen Kinetik während der Standphase waren jedoch kleiner als die in der Schwung beobachtet. Daher sollten Forscher mit Schwerpunkt auf der Schwungphase des Gehens die Auswirkungen der prosthes betrachtenTrägheit ist Eigentum Schätzungen auf Studienergebnissen. Für Haltung, würde entweder eine der beiden Trägheits Modelle in unserer Studie untersucht, wahrscheinlich ähnliche Ergebnisse mit einer inversen Dynamik Beurteilung führen.

Inertial properties of the prosthetic leg distal to the knee were lower than those of the intact leg (Table 1). Averaged across participants, prosthetic side mass was 39% less, moment of inertia about a transverse axis through the knee was 52% less, and the center of mass location was 24% closer to the knee compared with values for the intact leg.
<table border="1" cellpadding="0" cellspacing="0" fo:keep-together.within-page="always" width="553">
	<tbody>
		<tr>
			<td>Subject</td>
			<td>Intact* Mass (kg)</td>
			<td>Pros&#8224; Mass (kg)</td>
			<td>Est. Mass difference (kg)</td>
			<td>&#8225;Ikneeintact (kg&#183;m2)</td>
			<td>Ikneepros (kg&#183;m2)</td>
			<td>Intact CM below the knee joint (m)</td>
			<td>Pros CM below the knee joint (m)</td>
		</tr>
		<tr>
			<td>A</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>Mean &#177; STD</td>
			<td>6.17 &#177; 0.51</td>
			<td>3.80 &#177; 0.66</td>
			<td>2.36 &#177; 0.38</td>
			<td>0.578 &#177; 0.109</td>
			<td>0.274 &#177; 0.063</td>
			<td>0.258 &#177; 0.022</td>
			<td>0.196 &#177; 0.013</td>
		</tr>
	</tbody>
</table>
*Intact refers to values for the combined intact shank and foot. 
&#8224;Pros refers to values for the combined prosthesis and residual limb. 
&#8225;Moment of inertia about a transverse axis through the knee.
Table 1. Comparison of inertial properties between the prosthetic and intact limbs from the knee down.
Resultant joint forces (Figure 3) and moments (Figure 4) at the ankle, knee, and hip were affected by the inertial parameters used in the inverse dynamics model. Specifically, joint kinetics were reduced during swing initiation (~65% of the gait cycle) and swing termination (~95% of the gait cycle) when direct measures of prosthesis inertia were used in inverse dynamics assessments compared with regressions based on intact anatomy (Table 2). Effect sizes suggest these differences during swing were not trivial (&#8805;1.0). In addition, joint kinetic values increased on average by 80% during swing initiation and termination when intact inertial estimates were used compared with direct measures of the prosthesis inertial properties. Thus, when inertial properties of an intact limb were used to model the prosthetic side, joint kinetic profiles of the prosthetic side during swing more closely resembled those of an intact limb (see Figures 3 and 4). During stance, a number of statistical differences were observed. The largest effect size for any difference during stance was observed for the hip anterioposterior resultant joint force (ES = 0.86). Although this effect size is large and still considered as part of stance, the peak value for this measure occurred during terminal stance (~52%), or as the limb was transitioning into swing. Effect sizes for all other significant differences observed during stance ranged from 0.01 to 0.41, which would be considered small effects with the larger of these values being observed in the hip resultant joint reaction forces. Although significant differences were found during stance, these differences when considered in terms of the size of the difference (i.e., effect sizes) might lead one to question the meaningfulness of these differences.
<img alt="Figure 3" fo:content-width="5in" src="/files/ftp_upload/50977/50977fig3highres.jpg" width="500" /> 
Figure 3. Resultant joint reaction forces of the ankle, knee, and hip in the anterioposterior (left panels) and vertical directions (right panels). Data were averaged across subjects for presentation. The stance phase begins at 0% of the gait cycle with foot contact and ends at approximately 60% of the gait cycle with toe-off. Swing continues until the next foot contact of the same leg at 100% of the gait cycle. <a href="https://www.jove.com/files/ftp_upload/50977/50977fig3highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" fo:content-width="5in" src="/files/ftp_upload/50977/50977fig4highres.jpg" width="500" /> 
Figure 4. Resultant joint moments about a transverse axis (a.k.a, mediolateral axis) through the ankle, knee, and hip. Data were averaged across subjects for presentation. The stance phase begins at 0% of the gait cycle with foot contact and ends at approximately 60% of the gait cycle with toe-off. Swing continues until the next foot contact of the same leg at 100% of the gait cycle.
<img alt="Table 2" fo:content-width="6in" src="/files/ftp_upload/50977/50977table2.jpg" width="600" /> 
Table 2. Peak resultant joint reaction forces and moments averaged across subjects and statistical comparisons between the two inertial models for the prosthetic side's joint kinetics. Notes: Mean data are presented as mean(SD). % Gait Cycle column represents the average percentage across subjects where the peak value occurred for that variable. p&#60;.05 considered significant.

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

Body segmental inertial properties are required for inverse dynamics modeling. Using an oscillation and reaction board technique, inertial properties of below-knee prostheses were measured. Using direct measures of prosthesis inertia in the inverse dynamics model of the prosthetic leg resulted in lower magnitudes of resultant joint forces and moments.

Oszillation und Reaktionsvorstands Techniken zur Schätzung Inertial Eigenschaften einer Unterschenkelprothese

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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16.6K Aufrufe.  University of Northern Colorado. Body segmental inertial properties are required for inverse dynamics modeling. Using an oscillation and reaction board technique, inertial properties of below-knee prostheses were measured. Using direct measures of prosthesis inertia in the inverse dynamics model of the prosthetic leg resulted in lower magnitudes of resultant joint forces and moments.

Serie: 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).

Messung der mechanischen Eigenschaften von lebenden Zellen mit Atomic Force Microscopy

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

Forschung

Biotechnik

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.

Technische Plattform und experimentelles Protokoll für Entwurf und Evaluation eines Neural-kontrollierten Powered Oberschenkelprothese

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.

In-situ-Mapping der mechanischen Eigenschaften von Biofilmen durch Partikel-Tracking Mikrorheologie

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.

Techniken für die Entwicklung von robusten Pentose-gärenden Hefe für Biokonversion von Lignocellulose zu Ethanol

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.

Herstellung von Metallnanopartikeln durch gepulste Laserablation in Flüssigkeiten: Ein Werkzeug zum Studium der antibakteriellen Eigenschaften von Nanopartikeln

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.

Synthese von Hydrogelen mit Antifouling-Eigenschaften als Membranen für die Wasserreinigung

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.

Parallelisierter längs Microcomputed Tomographie-basierten quantitativen Strukturanalyse von einem nackten Rattenmodell Osteoporose bedingte Wirbelfraktur

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.

Ein Millimeter Skala Biege-Prüfsystem zur Messung der mechanischen Eigenschaften von marinen Schwamm Knochensplitter

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.

Synthese von Multi-walled Carbonnanotubes mit Silber-Nanopartikeln und Bewertung ihrer antibakteriellen Aktivitäten und zytotoxische Eigenschaften modifiziert

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.

3D-Druck von In-vitro-Hydrogel-Mikroträgern durch abwechselnd viskos-inertiales Kraft-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 ...