Name: quantifying arms and legs contributions during repetitive electrically-assisted sit-to-stand exercise in paraplegics: a pilot study
Uploaded: 2022-11-11T12:50:00
Description: Watch this Scientific Journal Video about Quantifying Arms and Legs Contributions during Repetitive Electrically-Assisted Sit-To-Stand Exercise in Paraplegics: A Pilot Study at JoVE.com

The authors acknowledge and appreciate&#160;all the SCI volunteers who participated in this study. This research was supported by the Ministry of Higher Education, Malaysia, and the University of Malaya through Fundamental Research Grant Scheme (FRGS) Grant No.&#160;FP002-2020;&#160;FRGS/1/2020/SKK0/UM/02/1.

The SitTS exercise and informed consent in this manuscript are described under ethical consideration by University of Malaya Medical Centre Ethics Committee (2017119-4828)12. Study procedures were explained in detail to each participant, and written informed consent was obtained before beginning the SitTS trial. This study was conducted as mixed-mode, where quantitative data were obtained using biomechanical analysis, whereas subjective scores were obtained from feedback sessions (of the participa...

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The current study demonstrated a bodyweight contribution in SCI individuals during SitTS exercise. This study presented SF as an essential assistive device for paraplegics to do a successful SitTS cycle. Moreover, an instrumented SF was developed to ensure the arms force can be assessed too28. The application of MMG was added in the study to observe prime SitTS muscle that helps researchers to understand SitTS performance better. Furthermore, the feedback session enabled researchers to obtain insi...

Sit-To-Stand (SitTS) is a significant movement in a human&#39;s activity of daily living (ADL). It is also a prerequisite for basic functional activities such as standing, transferring, and walking. For patients with incomplete spinal cord injury (SCI), paraplegics in particular, SitTS exercise is a crucial activity for their functional independence1,2. This exercise is essential for independence training, which eventually helps SCI population to improve their quality of life. In order to perform a sufficient and adequate SitTS exercise, the knowledge regarding their biomechanics and muscle activity should be feasibly measurable during the training.
In a clinical rehabilitation program, SCI patients with grade American Spinal Cord Injury Association (ASIA) Impairment Scale, AIS&#160;C have a better progression and chance of recovering their motor function than those with grade AIS B, who has complete motor deficits. The SitTS performance plays an important measure in an SCI patient to indicate their motor functionality during the recovery process3. However, SCI AIS C patients require both support from the upper and lower limbs to achieve successful series of repeated SitTS movements. The upper limb support plays an important role in unloading the knees while providing adequate lifting forces and assuring the body balance during the exercise4.
The purpose of this study is to describe the biomechanical contributions of arms and legs throughout repetitive SitTS in incomplete SCI individuals. This study positions the biomechanical analysis in relation to the participants&#39; subjective sense of their arms and legs muscle performance and feelings of &#39;effort and tiredness&#39; throughout the SitTS exercise.
Many previous SitTS studies only concentrated on investigating the kinematics and kinetics aspects of the activity4,5,6,7. In a wider context of SitTS training, the development of this method which includes the instrumented standing frame (SF) and force plate analysis, could lead researchers to assess both upper and lower limb contribution of other populations such as stroke, elderly, and patients with osteoarthritis8,9,10. A previous study by Zoulias et al., instrumented custom-built hardware and software of SF presented a large frame design11. This method can be challenging to replicate. Hence this SitTS study highlighted a portable instrumented SF that can be adopted by other researchers with an existing motion analysis laboratory setup.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Customade chair</td>
			<td></td>
			<td></td>
			<td>A customade chair was built to following to the force plate&#39;s dimension.</td>
		</tr>
		<tr>
			<td>FES RehaStim 2</td>
			<td>Hasomed</td>
			<td></td>
			<td>A device that can stimulate electrical current towards the muscle.</td>
		</tr>
		<tr>
			<td>FlexiForce A201</td>
			<td>Tekscan, Inc., USA</td>
			<td>Force ranges: 0-100 lbs. (440 N)</td>
			<td>Force sensors is used to capture arms force at standing frame.</td>
		</tr>
		<tr>
			<td>Foldable standing frame</td>
			<td></td>
			<td>Height: 70.0 cm - 90.0 cm.</td>
			<td>A walking frame that was bought from local medical company.</td>
		</tr>
		<tr>
			<td>Motion Analysis</td>
			<td>Vicon Oxford, UK</td>
			<td></td>
			<td>A system that records kinematic and kinetics of the activity.</td>
		</tr>
		<tr>
			<td>Serial port terminal application</td>
			<td>CoolTerm</td>
			<td>version 1.4.6; Roger Meier&#39;s</td>
			<td>An application to record the force sensor data.</td>
		</tr>
		<tr>
			<td>Vibromyography software</td>
			<td>BIOPAC System Inc., USA</td>
			<td>AcqKnowledge 4.3.1</td>
			<td>A software to record and strore raw MMG data. It also function for offline analyses.</td>
		</tr>
		<tr>
			<td>VMG transducers and BIOPAC Vibromyography system</td>
			<td>BIOPAC System Inc., USA</td>
			<td>BP150 and HLT100C</td>
			<td>A device to measure muscle activity.</td>
		</tr>
	</tbody>
</table>

quantifying arms and legs contributions during repetitive electrically-assisted sit-to-stand exercise in paraplegics: a pilot study

Execution of Sit-to-Stand (SitTS) in incomplete spinal cord injury (SCI) patients involves motor function in both upper and lower extremities. The use of arm support, in particular, is a significant assistive factor while executing SitTS movement in SCI population. In addition, the application of functional electrical stimulation (FES) onto quadriceps and gluteus maximus muscles is one of the prescribed management for incomplete SCI to improve muscle action for simple lower limb movements. However, the relative contribution of upper and lower extremities during SitTS has not been thoroughly investigated. Two motor incomplete SCI paraplegics performed repetitive SitTS to fatigue exercise challenge. Their performance was investigated as a mixed-method case-control study comparing SitTS with and without the assistance of FES. Three sets of SitTS tests were completed with 5-min resting period allocated in between sets, with mechanomyography (MMG) sensors attached over the rectus femoris muscles bilaterally. The exercise was separated into 2 sessions; Day 1 for voluntary SitTS and Day 2 for FES-assisted SitTS. Questionnaires were conducted after every session to gather the participants&#39; input about their repetitive SitTS experience. The analysis confirmed that a SitTS cycle could be divided into three phases; Phase 1 (Preparation to stand), Phase 2 (Seat-off), and Phase 3 (Initiation of hip extension), which contributed to 23% &#177; 7%, 16% &#177; 4% and 61% &#177; 6% of the SitTS cycle, respectively. The contribution of arms and legs during SitTS movement varied in different participants based on their legs&#39; Medical Research Council (MRC) muscle grade. In particular, the applied arm forces start to increase clearly when the leg forces start to decline during standing. This finding is supported by the significantly reduced MMG signal indicating leg muscle fatigue and their reported feeling of tiredness.

A total of 399 and 463 SitTS trials were completed without and with FES assisted correspondingly. The trials that contributed to each set are tabulated in Table 2. The participants could perform more SitTS trials with the presence of electrical stimulation on their legs, i.e., FES. Overall, both participants managed to perform more SitTS trials with the aid of FES. This suggests that FES helps in stimulating participants&#39; quadriceps to execute SitTS action in a prolonged period20</s...

Watch this Scientific Journal Video about Quantifying Arms and Legs Contributions during Repetitive Electrically-Assisted Sit-To-Stand Exercise in Paraplegics: A Pilot Study at JoVE.com

Quantifying Arms and Legs Contributions during Repetitive Electrically-Assisted Sit-To-Stand Exercise in Paraplegics: A Pilot Study

Arms contribution in Sit-To-Stand (SitTS) is determined by the legs' muscle condition. Several compensating strategies were discovered in efforts to achieve complete SitTS cycles. These findings triangulate the spinal cord injury (SCI) persons' biomechanical measures with their subjective feeling of load borne by both their limbs throughout the SitTS approaches.

Execution of Sit-to-Stand (SitTS) in incomplete spinal cord injury (SCI) patients involves motor function in both upper and lower extremities. The use of ...

This protocol demonstrates appropriate guidelines by explaining essential parts and how they're carried out in conducting a sit-to-stand experiment with the assistance of arm support and functional electrical stimulation. This technique helps manage the complexity of having a few sets up, including the instrumentation of a standing frame, functional electrical stimulation, and mechanomyography. This method can be applicable to other populations that require the setup of sit-to-stand with arm assistance.Demonstrating the procedure will be Khairul, an assistant in handling the MMG and FES setup. Adhli, an assistant in Vicon setup, and Musfirah a PhD candidate under Dr.Nur Azah Hamzaid's supervision. Begin the sit-to-stand experiment set up by arranging a chair and standing frame.To do so, design an armless chair with a height of 45 centimeters without a back rest according to the dimension of a force plate 1 embedded in the floor of the motion analysis laboratory. Next, instrument each SF leg at the bottom with an independent force sensor with a sensitivity range from 0 to 12 kilograms. Position a portable and foldable SF in front of the chair within arm's reach, and position four legs of the SF outside of force plate 2 to avoid double measurements.For motion analysis set up, enter the participant's details such as leg length, ankle width, and knee width in the system. Then, place 16 reflective markers on the participant's lower limbs with double-sided tape directly over the bilateral, anterior, and posterior of the superior iliac spine. Attach the marker over the lateral surface of the bilateral thigh and shank, and on the lateral left and right malleolus.Next, place markers over the left and right of the second metatarsal head, and on the calcaneus at the same height of the second metatarsal head. When done, instruct the participant to be seated barefoot, with the knees flexed at 90 degrees, and both feet positioned on force plate 2. Ensure the participant's head and trunk face forward while sitting upright.After placing the participant's hands on the handle of the SF, identify the rectus femoris muscle by palpating the middle and bulky area of the thigh, then place one mechanomyography, or MMG sensor per leg at the thigh area of the rectus femoris muscle bilaterally to measure the leg muscles sit-to-stand and stand-to-sit efforts. Secure the sensors with a double-sided tape and strap the sensors around the thigh to reduce the motion artifacts before connecting to the MMG device and the computer. On day one, perform a voluntary sit-to-stand exercise by turning on all setups to record the selected parameters.At the end of countdown of five seconds timed by an electronic timer, ask the participant to stand up from the stationary sitting position for three seconds before sitting back on the chair. After a rest of five seconds, continue to do sit-to-stand trials until the participant cannot perform the same routine any longer. When done, turn off all the recorded data.Give a five minute break before continuing the next set of the sit-to-stand routine to provide muscle recovery amongst sets. Once the trial is over, allow the participant to rest for at least 48 hours. On day two, place functional electrical stimulation electrodes on the quadriceps and gluteus maximus muscles to perform the FES assisted sit-to-stand exercise.For quadriceps muscle, place the first electrode horizontally about two finger widths above the knee, and the second electrode horizontally about a palm width below the hip joint. For the gluteus maximus muscle, instruct the participant to bend forward to place the first electrode vertically, closest to the hip bone, and attach the second electrode vertically, closest to the tailbone, side-by-side from the first electrode. When the electrodes are in place, attach all FES electrodes to the FES device and connect them to the FES software in the computer.Set up the FES software by selecting the pulse width of 300 and the frequency of 35 hertz. To define the FES current intensity, inquire if the participant can tolerate the current to achieve knee and hip extension. Determine the FES current amplitude through several practices before starting the actual trial.Next, start the experiment as described earlier by switching the FES on as the participant stands up and switching the FES off to let the participant sit back on the chair. Repeat the trial in sets and collect the data. Throughout the sit-to-stand action in both sessions, participant 1's arm percentage showed a higher contribution to total body weight percentage as compared to his leg percentage.In participant 1, the electrical stimulation could not provide a full extension in the right knee during the end phase of the sit-to-stand routine. The right knee angle did not reach the normal knee extension range of motion. In contrast, participant 2 exerted more strength onto her legs to bear the full body weight, with a higher contribution of leg percent during the end phase of the voluntary sit-to-stand routine.In addition, during the final set of voluntary sit-to-stand routine, participant 2 exhibited a smaller knee angle during the early stage of the movement. During event B, when the buttocks lift up was initiated, participant 1 was observed to increase arm strength to lift his upper body from the chair. Meanwhile, for participant 2, the maximum contribution of arms was detected during event B, for FES assisted sit-to-stand routine.Each step in this procedure is important and should be followed as stated. However, it is necessary to note that there can be flexibility, specifically in the initial posture of the participant. Qualitative feedback can be added in order to measure opinions and views regarding the sit-to-stand routines, stability, and fatigue from the participant's perspective.By adding this method, researchers will better understand the sit-to-stand technique's behavior with the quantitative results achieved.

quantifying-arms-legs-contributions-during-repetitive-electrically

Research

JoVE Journal

Engineering

Micro 3D Printing Using a Digital Projector and its Application in the Study of Soft Materials Mechanics

Buckling is a classical topic in mechanics. While buckling has long been studied as one of the major structural failure modes1, it has recently drawn new attention as a unique mechanism for pattern transformation. Nature is full of such examples where a wealth of exotic patterns are formed through mechanical instability2-5. Inspired by this elegant mechanism, many studies have demonstrated creation and transformation of patterns using soft materials such as elastomers and hydrogels6-11. Swelling gels are of particular interest because they can spontaneously trigger mechanical instability to create various patterns without the need of external force6-10. Recently, we have reported demonstration of full control over buckling pattern of micro-scaled tubular gels using projection micro-stereolithography (P&mu;SL), a three-dimensional (3D) manufacturing technology capable of rapidly converting computer generated 3D models into physical objects at high resolution12,13. Here we present a simple method to build up a simplified P&mu;SL system using a commercially available digital data projector to study swelling-induced buckling instability for controlled pattern transformation.
A simple desktop 3D printer is built using an off-the-shelf digital data projector and simple optical components such as a convex lens and a mirror14. Cross-sectional images extracted from a 3D solid model is projected on the photosensitive resin surface in sequence, polymerizing liquid resin into a desired 3D solid structure in a layer-by-layer fashion. Even with this simple configuration and easy process, arbitrary 3D objects can be readily fabricated with sub-100 &mu;m resolution.
This desktop 3D printer holds potential in the study of soft material mechanics by offering a great opportunity to explore various 3D geometries. We use this system to fabricate tubular shaped hydrogel structure with different dimensions. Fixed on the bottom to the substrate, the tubular gel develops inhomogeneous stress during swelling, which gives rise to buckling instability. Various wavy patterns appear along the circumference of the tube when the gel structures undergo buckling. Experiment shows that circumferential buckling of desired mode can be created in a controlled manner. Pattern transformation of three-dimensionally structured tubular gels has significant implication not only in mechanics and material science, but also in many other emerging fields such as tunable matamaterials.

We demonstrate controlled pattern transformation of swelling gel tubes by elastic instability. A simple projection micro stereo-lithography setup is built using an off-the-shelf digital data projector to fabricate three-dimensional polymeric structures in a layer-by-layer fashion. Swelling hydrogel tubes under mechanical constraint display various circumferential buckling modes depending on dimension.

Buckling is a classical topic in mechanics. While buckling has long been studied as one of the major structural failure modes1, it has recently drawn new ...

Coherent anti-Stokes Raman Scattering (CARS) Microscopy Visualizes Pharmaceutical Tablets During Dissolution

Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This method provides little direct information about what is happening on the surface of the dissolving tablet. As the tablet surface composition and structure can change during dissolution, it is essential to monitor it during dissolution testing. In this work coherent anti-Stokes Raman scattering microscopy is used to image the surface of tablets during dissolution while UV absorption spectroscopy is simultaneously providing inline analysis of dissolved drug concentration for tablets containing a 50% mixture of theophylline anhydrate and ethyl cellulose. The measurements showed that in situ CARS microscopy is capable of imaging selectively theophylline in the presence of ethyl cellulose. Additionally, the theophylline anhydrate converted to theophylline monohydrate during dissolution, with needle-shaped crystals growing on the tablet surface during dissolution. The conversion of theophylline anhydrate to monohydrate, combined with reduced exposure of the drug to the flowing dissolution medium resulted in decreased dissolution rates. Our results show that in situ CARS microscopy combined with inline UV absorption spectroscopy is capable of monitoring pharmaceutical tablet dissolution and correlating surface changes with changes in dissolution rate.

Coherent anti-Stokes Raman Scattering CARS Microscopy Visualizes Pharmaceutical Tablets During Dissolution

Coherent anti-Stokes Raman scattering (CARS) microscopy is combined with an intrinsic flow-through dissolution setup to allow in situ and real-time visualization of the surface of pharmaceutical tablets undergoing dissolution. Using this custom-built setup, it is possible to correlate CARS videos with drug dissolution profiles recorded using inline UV absorption spectroscopy.

Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. 
Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.
The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

Development of new ablative materials and their numerical modeling requires extensive experimental investigation. This protocol describes procedures for material response characterization in plasma flows with the core techniques being non-intrusive methods to track the material recession along with the chemistry in the reactive boundary layer by emission spectroscopy.

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

A Robotic Platform to Study the Foreflipper of the California Sea Lion

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most of their thrust with their large foreflippers. This protocol describes a robotic platform designed to study the hydrodynamic performance of the swimming California sea lion (Zalophus californianus). The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;). The kinematics of the sea lion&#39;s propulsive stroke are extracted from video data of unmarked, non-research sea lions at the Smithsonian Zoological Park (SNZ). Those data form the basis of the actuation motion of the robotic flipper presented here. The geometry of the robotic flipper is based a on high-resolution laser scan of a foreflipper of an adult female sea lion, scaled to about 60% of the full-scale flipper. The articulated model has three joints, mimicking the elbow, wrist and knuckle joint of the sea lion foreflipper. The robotic platform matches dynamics properties&#8212;Reynolds number and tip speed&#8212;of the animal when accelerating from rest. The robotic flipper can be used to determine the performance (forces and torques) and resulting flowfields.

A robotic platform is described that will be used to study the hydrodynamic performance&#8212;forces and flowfields&#8212;of the swimming California sea lion. The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;).

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most ...

Challenges in Rheological Characterization of Highly Concentrated Suspensions &#8212; A Case Study for Screen-printing Silver Pastes

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the manifold requirements during processing and application of such complex fluids. In this investigation, measuring protocols for a conclusive assessment of different process relevant rheological parameters have been evaluated. This includes the determination of yield stress, viscosity, wall slip velocity, structural recovery after large deformation and elongation at break as well as tensile force during filament stretching.
The importance of concomitant video recordings during parallel-plate rotational rheometry for a significant determination of rheological quantities is demonstrated. The deformation profile and flow field at the sample edge can be determined using appropriate markers. Thus, measurement parameter settings and plate roughness values can be identified for which yield stress and viscosity measurements are possible. Slip velocity can be measured directly and measuring conditions at which plug flow, shear banding or sample spillover occur can be identified clearly. 
Video recordings further confirm that the change in shear moduli observed during three stage oscillatory shear tests with small deformation amplitude in stage I and III but large oscillation amplitude in stage II can be directly attributed to structural break down and recovery. For the pastes investigated here, the degree of irreversible, shear-induced structural change increases with increasing deformation amplitude in stage II until a saturation is reached at deformations corresponding to the crossover of G' and G'', but the irreversible damage is independent of the duration of large amplitude shear. 
A capillary breakup elongational rheometer and a tensile tester have been used to characterize deformation and breakup behavior of highly filled pastes in uniaxial elongation. Significant differences were observed in all experiments described above for two commercial screen-printing silver pastes used for front side metallization of Si-solar cells.

Challenges in Rheological Characterization of Highly Concentrated Suspensions &amp;#8212; A Case Study for Screen-printing Silver Pastes

A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems.

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the ...

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for Cu(In,Ga)Se2 Solar Cells

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction of degradation mechanisms and prevention of module field failure can consequently decrease investment risks as well as increase the electricity yield. An improved knowledge level can for these reasons significantly decrease the total costs of PV electricity. 
In order to better understand and minimize the degradation of PV modules, the occurring degradation mechanisms and conditions should be identified. This should preferably happen under combined stresses, since modules in the field are also simultaneously exposed to multiple stress factors. Therefore, two 'Combined Stress test with in situ measurement' setups have been designed and constructed. These setups allow the simultaneous use of humidity, temperature, illumination, and electrical biases as independently controlled stress factors on solar cells and minimodules. The setups also allow real-time monitoring of the electrical properties of these samples. This protocol presents these setups and describes the experimental possibilities. Moreover, results obtained with these setups are also presented: various examples about the influence of both deposition and degradation conditions on the stability of thin film Cu(In,Ga)Se2 (CIGS) as well as Cu2ZnSnSe4 (CZTS) solar cells are described. Results on the temperature dependency of CIGS solar cells are also presented.

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for CuIn,GaSe2 Solar Cells

Two &#39;Combined Stress test with in situ measurement&#39; setups, which allow real-time monitoring of accelerated degradation of solar cells and modules, were designed and constructed. These setups allow the simultaneous use of humidity, temperature, electrical biases, and illumination as independently controlled stress factors. The setups and various experiments executed are presented.

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction ...

Study of Siphon Breaker Experiment and Simulation for a Research Reactor

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent this outflow, a control device is required. A siphon breaker is a type of safety device that can be utilized to control the loss of coolant water effectively.
To analyze the characteristics of siphon breaking, a real-scale experiment was conducted. From the results of the experiment, it was found that there are several design factors that affect the siphon breaking phenomenon. Therefore, there is a need to develop a theoretical model capable of predicting and analyzing the siphon breaking phenomenon under various design conditions. Using the experimental data, it was possible to formulate a theoretical model that accurately predicts the progress and the result of the siphon breaking phenomenon. The established theoretical model is based on fluid mechanics and incorporates the Chisholm model to analyze two-phase flow. From Bernoulli&#39;s equation, the velocity, quantity, undershooting height, water level, pressure, friction coefficient, and factors related to the two-phase flow could be obtained or calculated. Moreover, to utilize the model established in this study, a siphon breaker analysis and design program was developed. The simulation program operates on the theoretical model basis and returns the result as a graph. The user can confirm the possibility of the siphon breaking by checking the shape of the graph. Furthermore, saving the entire simulation result is possible and it can be used as a resource for analyzing the real siphon breaking system.
In conclusion, the user can confirm the status of the siphon breaking and design the siphon breaker system using the program developed in this study.

The siphon breaking phenomenon was investigated experimentally and a theoretical model was proposed. A simulation program based on the theoretical model was developed and the results of the simulation program were compared with experimental results. It was concluded that the results of the simulation program matched the experimental results well.

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent ...

Film Control to Study Contributions of Waves to Droplet Impact Dynamics on Thin Flowing Liquid Films

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous studies on flowing liquid films have neglected the contributions of spatial structures of waves to the impact outcome, while this has recently been shown to have a significant influence on the drop impact dynamics. In this report, we outline a step-by-step procedure to investigate the effect of periodic inlet forcing of a flowing liquid film leading to the production of spatiotemporally regular wave structures on drop impact dynamics. A function generator in connection with a solenoid valve is used to excite these spatiotemporally regular wave structures on the film surface while the impact dynamics of uniform-sized droplets are captured using a high-speed camera. Three distinct regions are then studied; viz. the capillary wave region preceding the large wave peak, the flat film region, and the wave hump region. The effects of important dimensionless quantities such as film Reynolds, drop Weber and Ohnesorge numbers parameterized by the film flow rate, drop speed, and drop size are also examined. Our results show interesting, hitherto undiscovered dynamics brought about by this application of film inlet forcing of the flowing film for both low and high inertia drops.

A protocol to study the contributions of waves to droplet impact dynamics on flowing liquid films is presented.

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous ...

Study of a Dot-patterning Process on Flexible Materials using Impact Print-Type Hot Embossing Technology

Here we present our study on an impact print-type hot embossing process which can create dot patterns with various designs, widths, and depths in real time on polymer film. In addition, we implemented a control system for the on-off motion and position of the impact header to engrave different dot patterns. We performed dot patterning on various polymer films, such as polyester (PET) film, polymethyl methacrylate (PMMA) film, and polyvinyl chloride (PVC) film. The dot patterns were measured using a confocal microscope, and we confirmed that the impact print-type hot embossing process produces fewer errors during the dot patterning process. As a result, the impact print-type hot embossing process is found to be suitable for engraving dot patterns on different types of polymer films. In addition, unlike the conventional hot embossing process, this process does not use an embossing stamp. Therefore, the process is simple and can create dot patterns in real time, presenting unique advantages for mass production and small-quantity batch production.

Impact print-type hot embossing technology uses an impact header to engrave dot patterns on flexible materials in real time. This technology has a control system for controlling the on-off motion and position of the impact header to create dot patterns with various widths and depths on different polymer films.

Here we present our study on an impact print-type hot embossing process which can create dot patterns with various designs, widths, and depths in real ...