Name: surgical techniques for catheter placement and 5/6 nephrectomy in murine models of peritoneal dialysis
Uploaded: 2018-07-19T13:00:00
Description: Watch this Scientific Journal Video about Surgical Techniques for Catheter Placement and 5/6 Nephrectomy in Murine Models of Peritoneal Dialysis at JoVE.com

Authors thank E. Ferrantelli and G. Liappas for their support setting the 5/6 nephrectomy protocol, R. S&#225;nchez-D&#237;az and P. Mart&#237;n for the assistance with ureic nitrogen assessments, and E. Hevia and F. N&#250;&#241;ez for the assistance with mice care. This work was supported by grants SAF2016-80648R from the &#34;Ministerio de Econom&#237;a y Competitividad&#34;/Fondo Europeo de Desarrollo Regional (MINECO/FEDER) to Manuel L&#243;pez-Cabrera and PI 15/00598 from&#160;Fondo de Investigaciones Sanitarias (FIS)-FEDER funds, to Abelardo Aguilera.

All methods described here have been approved by the Institutional Animal Care and Use Committee of the Molecular Biology Center Severo Ochoa (Madrid, Spain).
Note: C57BL/6J female mice aged 12 to 14 weeks and weighing approximately 20 g at the start of the study were used. All the animals were housed under standard conditions and were given food and water ad libitum. Health conditions were checked daily.&#160;The material required, such as gloves, drape, catheter, suture and needles,...

The first published data analyzing PD alterations by using a &#34;close system&#34; technique was performed in 200929 . This close system means that the entire device is located inside the body and fluid is injected with a needle through an access port. The most important technical problem in long-term animal models of fluid infusion through a catheter is the occurrence of obstruction. Possible options are to perform omentectomy or add heparin to the PDFs to reduce peritoneal adhesions. Neverthele...

Kidney Function and Renal Disease
Kidneys are essential organs involved in homeostasis, blood filtration and hormone production. There are various conditions that lead to kidney failure and to the subsequent onset of uremia, which has been defined as the group of systemic symptoms due to the accumulation of waste products in the blood retained due to kidney function disorders1. Moreover, since homeostatic capability is also affected when there is a renal failure, hypertension due to volume overload may occur, which is also dangerous as it can lead to heart failure1. When the functional capability of kidneys is less than 10%-15%, the patient must undergo one of the following therapeutic options: hemodialysis, peritoneal dialysis (PD) or renal transplantation.
PD is an interesting option that allows patients to continue treatment from the comfort of their home or practically anywhere, thus avoiding the need for frequent hospital visits and stays. The PD technique eliminates small toxic molecules and excess water generated by the body2 through the instillation of an osmotic fluid (peritoneal dialysis fluid, PDF) into the peritoneal cavity. This instillation generates the osmotic gradient necessary for the exchange of solutes and water between the peritoneal capillary and PDF, a process known as ultrafiltration (UF).
Peritoneal Injury Induced by Peritoneal Dialysis
The peritoneal cavity is covered by a membrane (PM) composed of a monolayer of mesothelial cells resting on a matrix, which also houses few blood vessels, fibroblasts, macrophages and other cell populations. Unfortunately, the peritoneal membrane always suffers some alterations during PD treatment, such as apoptosis and loss of mesothelial cells, mesenchymal transition of mesothelial (MMT) and endothelial (end-MT) cells, recruitment of inflammatory cells and fibrocytes, vascular alterations, angiogenesis, lymphangiogenesis and/or fibrosis3,4,5,6,7,8,9. These alterations are responsible for the development of an UF capacity failure10, which precludes the continuation of the therapy, requiring that the patient must receive an alternative treatment to survive (hemodialysis or renal transplantation). Therefore, for these patients, it is essential to delay or control the development of these peritoneal alterations.
It has been speculated that uremia alone may cause inflammation11, but the most important local factor is PDF bioincompatibility. Most PDFs use glucose as the osmotic agent, which causes inflammation. Due to PDF storage times and sterilization, glucose suffers a process of degradation, and new products from this reaction appear, generating more inflammation, MMT and apoptosis12,13. Moreover, there is also the possibility of mechanical damage due to the instillation method. All these factors, acting continuously, may generate a persistent and recurrent inflammatory state, leading to chronic inflammation, which drives to membrane deterioration and, conclusively, UF failure. How this damage could be reduced or avoided is still a matter of study.
Analyzing the Development of Lesions: From Human Samples to Animal Models
Working with human biopsies is a limiting factor due to the difficulty in obtaining tissue samples. These samples can only be obtained from surgeries performed due to catheter malfunction or transplantation, usually after years of PD treatment. This approach is useful for the analysis of pathological changes suffered by a peritoneal membrane exposed to PDF, but is not sufficient to study the development of the process. Another possibility is to analyze cells drained from dialysis effluent, but this still fails to provide a complete scenario. Merging both techniques is only possible with animal models. The peritoneal structure is similar among mammals, and therefore there are models with different animal species. There are a few studies based on sheep (Rodela et al.14 and Barrell et al.15) and rabbit16,17 models; however, smaller animals are preferable as they are easier to house and maintain, and are also more economical. The use of rats18,19,20,21,22,23,24 offers a shorter treatment time needed to observe morpho-functional alterations. It has represented a very useful model to explore different issues such as the effect of anti-fibrotic drugs as for example BMP-7 (bone morphogenic protein-7)25 and RAS (renin-angiotensin system) targeting26,27,28.
However, the murine model has emerged as an ideal model with many benefits over others. The most interesting advantage is the possibility of using genetically modified mice to study the molecular and cellular basis of peritoneal damage. In fact, mice are often employed for the analysis of numerous diseases, as there are many different strains with various well-known genetic backgrounds. Other advantages include the reduced space required for housing, reduced cost of experiments (due to the animals&#39; smaller size), ease of handling, the availability of reagents and the increasing amount of available information on the different strains of mice since they have been most commonly used animals in research.
A mice-based model employing an implanted device has been the most recently established model for PD29,30, and has been shown to mimic peritoneal deterioration suffered by PD patients due to exposure to PDFs. This model has collaborated to understand the pathological processes implicated31,32,33. Moreover, it has been used to validate various potential treatments for ameliorating this deterioration using immune modulators and anti-inflammatory drugs and other anti-fibrotic and anti-angiogenic agents, such as COX-2 (cyclooxygenase-2) inhibitors34, PPAR-&#947; (peroxisome proliferator-activated receptor-&#947;) agonists35, Tamoxifen36, Paricalcitol (a vitamin D receptor activator that modulates the immune reaction)37, Rapamycin38 and Nebivolol39.
Developing the Mouse Model with an Implanted Catheter
The goal of this model is to resemble, as much as possible, the technique used in human PD patients, allowing to perform extended treatments of PD in small animals. So far, three techniques for instillation of dialysis fluid into the peritoneum have been tested in mice. The first one, blind puncture of the front abdominal wall, is controversial due to the multiple risks that it may incur, such as peritoneal damage, bleeding and, as is blindly performed, visceral puncture. The second technique is the so-called &#34;open permanent system&#34;, in which the device for injecting the fluid is placed outside the body. This procedure is most similar to that performed in humans. However, it does not allow the development of long-term experiments, as it may increase the chances of infection, and generally requires the use of anesthesia to instill PDF, which may interfere with the results. The third technique is the &#34;closed system&#34;. With this approach, the entire device used for fluid instillation is located inside the animal&#39;s body. Fluid is injected with a needle through an access port, which is placed subcutaneously. This procedure reduces the risk of peritoneal infection and bleeding as well as the need for anesthesia.
To study the effect of uremia in PD, a recent murine model has also been stablished40 based on the PDF infusion model with catheter. This model brings in a novel technique to perform a nephrectomy in mice, thus reducing renal function. In the present article, a modification of the protocol employed by Ferrantelli et al. in 201540 has been developed. This new protocol allows catheter implantation while nephrectomy, reduces the length of the wound inflicted during surgery and facilitates access to the kidneys.

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surgical techniques for catheter placement and 5/6 nephrectomy in murine models of peritoneal dialysis

Peritoneal dialysis (PD) is a renal replacement therapy consistent on the administration and posterior recovery of a hyperosmotic fluid in the peritoneal cavity to drain water and toxic metabolites that functionally-insufficient kidneys are not able to eliminate. Unfortunately, this procedure deteriorates the peritoneum. Tissue damage triggers the onset of inflammation to heal the injury. If the injury persists and inflammation becomes chronic, it may lead to fibrosis, which is a common occurrence in many diseases. In PD, chronic inflammation and fibrosis, along with other specific processes related to these ones, lead to ultrafiltration capacity deterioration, which means the failure and subsequent cessation of the technique. Working with human samples provides information about this deterioration but presents technical and ethical limitations to obtain biopsies. Animal models are essential to study this deterioration since they overcome these shortcomings.
A chronic mouse infusion model was developed in 2008, which benefits from the wide range of genetically modified mice, opening up the possibility of studying the mechanisms involved. This model employs a customized device designed for mice, consisting of a catheter attached to an access port that is placed subcutaneously at the back of the animal. This procedure avoids continuous puncture of the peritoneum during long-term experiments, reducing infections and inflammation due to injections. Thanks to this model, peritoneal damage induced by chronic PD fluid exposure has been characterized and modulated. This technique allows the infusion of large volumes of fluids and could be used for the study of other diseases in which inoculation of drugs or other substances over extended periods of time is necessary.
This article shows the method for the surgical placement of the catheter in mice. Moreover, it explains the procedure for a 5/6 nephrectomy to mimic the state of renal insufficiency present in PD patients.

Figure 1 shows all the materials required to follow the procedures described in protocol section. For this example, mice submitted or not to nephrectomy (8 animals per group) (Figure 2) were exposed during 40 days (two injections per day, waiting at least 2 hours between both) to a mixture of two different PDFs, commonly used in the clinical practice: Extraneal (icodextrin-based PDF) and Dianeal (glucose-based PDF). A group with ...

Watch this Scientific Journal Video about Surgical Techniques for Catheter Placement and 5/6 Nephrectomy in Murine Models of Peritoneal Dialysis at JoVE.com

Surgical Techniques for Catheter Placement and 5/6 Nephrectomy in Murine Models of Peritoneal Dialysis

This article shows the method for the surgical placement in mice of an intraperitoneal catheter attached to an access port that is positioned at the back of the animal. Moreover, it explains the procedure for a 5/6 nephrectomy to resemble the uremic state of PD patients.

Peritoneal dialysis (PD) is a renal replacement therapy consistent on the administration and posterior recovery of a hyperosmotic fluid in the peritoneal ...

This method can help answer key questions in the Peritoneal Dialysis field about Peritoneal or Systemic alterations in response to fluid exposure either under uremic or not uremic conditions. The main advantages of this technique are that large amounts of fluid can be injected intraperitoneally over a long treatment period and that it allows the use of genetically modified animals. The implication of this technique extend toward the therapy and diagnostics of structural and functional peritoneal deterioration, as it facilitates potential, therapeutic strategic testing and biomarker evaluation.We first had the idea for this method when we anticipated the need for using genetically modified mice to starting the molecular cues involved in peritoneal damage. For catheter placement, after shaving the right flanks and backs of each animal, confirm a lack of response to toe pinch and apply ointment to the animal's eyes. Next, place the first animal on its left flank on the surgical table and disinfect the exposed skin with 1%chlorhexidine gluconate solution.Use blunt scissors to make a 0.5 centimeter cut skin incision on the right flank of the body. Then, carefully separate the skin from the adjacent muscle layer until the skin covering the entire back of the animal is well separated. Make a one millimeter diameter incision in the muscle layer through the skin incision and insert the tip of the catheter and the first plastic ring into the muscle incision.Suture the peritoneal wall tightly around the catheter with the 5-0 or 6-0 non-absorbable suture, with one plastic ring inside the peritoneal cavity and the other between the muscle and the skin. The sutures should be prepared before the incision is made and the muscle should not be released until the catheter is inserted. Otherwise, since the incision is very small, it could be difficult to find it again.Insert the access port into the subcutaneous space towards the tail of the mouse and close the wound with a second suture. Then, return the animal to its cage after full sternal recumbency. Four to seven days later, to initiate the peritoneal dialysis treatment, first load a syring with two milliliters of peritoneal dialysis fluid, and disinfect the skin surrounding the port with 1%chlorhexidine gluconate solution.Then use one hand to restrain the animal by the tail and access port, and inject the fluid into the port with the other hand using a beveled needle. For a 5/6 Nephrectomy and catheter placement, after preparing the animals for surgery, as demonstrated, make a 0.5 centimeter skin incision on the left side of the animal close to the bottom of the ribs. Open a small incision in the muscle to extract the left kidney from the peritoneum, and remove the capsule and the adrenal gland.Use a cauterizer to burn and cut the extremities of the kidney and return the kidney to the peritoneal cavity. Then, close the muscle and the skin wounds with insoluble 5-0 or 6-0 sutures and return the animal to its cage when it has fully recovered. The next day, make a 0.5 centimeter skin incision on the right side of the animal and separate the skin at the back of the animal from the muscle, as demonstrated.Make a 0.3 to 0.4 centimeter incision in the muscle and extract the right kidney from the peritoneal cavity. Remove the capsule and the adrenal gland and use a non-absorbable 5-0 or 6-0 suture to ligate the kidney vein, artery, and ureter. Now remove the kidney completely and insert the catheter so that the muscle is maintained between the two plastic rings, as demonstrated, before closing the muscle wound.Introduce the access port into the sub-cutaneous space and close the skin, as demonstrated. Then return the animal to its cage with monitoring until full recovery, and allow the animal to recover for at least 10 days before administering the hyperosmotic fluid, as demonstrated. Mouse perial peritoneal tissues obtained from the most distant area of the catheter, demonstrate an increased thickness and cell recruitment during dialysis that is further aggravated in the nephrectomized animals.Thymus epithelial cells also exhibit an altered morphology due to inter-cellular union degradation induced by the peritoneal dialysis. Serum samples from nephrectomized mice, indicate that a 5/6 Nephrectomy induces a uremic state, increasing the Ureic Nitrogen levels during the course of the experiment, compared to baseline. More over, when the kidneys are fully functional, the Ureic Nitrogen levels remain similar to the basal state, even in mice exposed to peritoneal dialysis fluid.These techniques can be completed in five to seven minutes. Without the nephrectomy, 15 to 20 minutes. For the left kidney cauterization, 20 to 25 minutes.For the right kidney removal and catheter placement, if its methodology is performed properly. After its development, this technique paved the way for researchers in the field of peritoneal dialysis to explore therapeutic options for peritoneal preservation in renal patients subjected to peritoneal dialysis treatment.

surgical-techniques-for-catheter-placement-56-nephrectomy-murine

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Setting Limits on Supersymmetry Using Simplified Models

Experimental limits on supersymmetry and similar theories are difficult to set because of the enormous available parameter space and difficult to generalize because of the complexity of single points. Therefore, more phenomenological, simplified models are becoming popular for setting experimental limits, as they have clearer physical interpretations. The use of these simplified model limits to set a real limit on a concrete theory has not, however, been demonstrated. This paper recasts simplified model limits into limits on a specific and complete supersymmetry model, minimal supergravity. Limits obtained under various physical assumptions are comparable to those produced by directed searches. A prescription is provided for calculating conservative and aggressive limits on additional theories. Using acceptance and efficiency tables along with the expected and observed numbers of events in various signal regions, LHC experimental results can be recast in this manner into almost any theoretical framework, including nonsupersymmetric theories with supersymmetry-like signatures.

This paper demonstrates a protocol for recasting experimental simplified model limits into conservative and aggressive limits on an arbitrary new physics model. Publicly available LHC experimental results can be recast in this manner into limits on almost any new physics model with a supersymmetry-like signature.

Experimental limits on supersymmetry and similar theories are difficult to set because of the enormous available parameter space and difficult to ...

Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. During insertion or removal of alkali metal ions, the redox states of transition metals in the compounds change and structural transformations such as phase transitions and/or lattice parameter increases or decreases occur. These behaviors in turn determine important characteristics of the batteries such as the potential profiles, rate capabilities, and cycle lives. The extremely bright and tunable x-rays produced by synchrotron radiation allow rapid acquisition of high-resolution data that provide information about these processes. Transformations in the bulk materials, such as phase transitions, can be directly observed using X-ray diffraction (XRD), while X-ray absorption spectroscopy (XAS) gives information about the local electronic and geometric structures (e.g.&#160;changes in redox states and bond lengths). In situ experiments carried out on operating cells are particularly useful because they allow direct correlation between the electrochemical and structural properties of the materials. These experiments are time-consuming and can be challenging to design due to the reactivity and air-sensitivity of the alkali metal anodes used in the half-cell configurations, and/or the possibility of signal interference from other cell components and hardware. For these reasons, it is appropriate to carry out ex situ experiments (e.g.&#160;on electrodes harvested from partially charged or cycled cells) in some cases. Here, we present detailed protocols for the preparation of both ex situ and in situ samples for experiments involving synchrotron radiation and demonstrate how these experiments are done.

We describe the use of synchrotron X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques to probe details of intercalation/deintercalation processes in electrode materials for Li-ion and Na-ion batteries. Both in situ and ex situ experiments are used to understand structural behavior relevant to the operation of devices

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. ...

Thermal Measurement Techniques in Analytical Microfluidic Devices

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. Micromachining techniques allow reduction of the thermal mass of fabricated structures and introduce the possibility to perform high sensitivity thermal measurements in the micro-scale and nano-scale devices. Combining thermal measurement techniques with microfluidic devices allows performing different analytical measurements with low sample consumption and reduced measurement time by integrating the miniaturized system on a single chip. The procedures of thermal measurement techniques for particle detection, material characterization, and chemical detection are introduced in this paper.

Here, we present three protocols for thermal measurements in microfluidic devices.

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. ...

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 ...

3D Printing of Biomolecular Models for Research and Pedagogy

The construction of physical three-dimensional (3D) models of biomolecules can uniquely contribute to the study of the structure-function relationship. 3D structures are most often perceived using the two-dimensional and exclusively visual medium of the computer screen. Converting digital 3D molecular data into real objects enables information to be perceived through an expanded range of human senses, including direct stereoscopic vision, touch, and interaction. Such tangible models facilitate new insights, enable hypothesis testing, and serve as psychological or sensory anchors for conceptual information about the functions of biomolecules. Recent advances in consumer 3D printing technology enable, for the first time, the cost-effective fabrication of high-quality and scientifically accurate models of biomolecules in a variety of molecular representations. However, the optimization of the virtual model and its printing parameters is difficult and time consuming without detailed guidance. Here, we provide a guide on the digital design and physical fabrication of biomolecule models for research and pedagogy using open source or low-cost software and low-cost 3D printers that use fused filament fabrication technology.

Physical models of biomolecules can facilitate an understanding of their structure-function for the researcher, aid in communication between researchers, and serve as an educational tool in pedagogical endeavors. Here, we provide detailed guidance for the 3D printing of accurate models of biomolecules using fused filament fabrication desktop 3D printers.

The construction of physical three-dimensional (3D) models of biomolecules can uniquely contribute to the study of the structure-function relationship. 3D ...

Gain-compensation Methodology for a Sinusoidal Scan of a Galvanometer Mirror in Proportional-Integral-Differential Control Using Pre-emphasis Techniques

Galvanometer mirrors are used for optical applications such as target tracking, drawing, and scanning control because of their high speed and accuracy. However, the responsiveness of a galvanometer mirror is limited by its inertia; hence, the gain of a galvanometer mirror is reduced when the control path is steep. In this research, we propose a method to extend the corresponding frequency using a pre-emphasis technique to compensate for the gain reduction of galvanometer mirrors in sine-wave path tracking using proportional-integral-differential (PID) control. The pre-emphasis technique obtains an input value for a desired output value in advance. Applying this method to control the galvanometer mirror, the raw gain of a galvanometer mirror in each frequency and amplitude for sine-wave path tracking using a PID controller was calculated. Where PID control is not effective, maintaining a gain of 0 dB to improve the trajectory tracking accuracy, it is possible to expand the speed range in which a gain of 0 dB can be obtained without tuning the PID control parameters. However, if there is only one frequency, amplification is possible with a single pre-emphasis coefficient. Therefore, a sine wave is suitable for this technique, unlike triangular and sawtooth waves. Hence, we can adopt a pre-emphasis technique to configure the parameters in advance, and we need not prepare additional active control models and hardware. The parameters are updated immediately within the next cycle because of the open loop after the pre-emphasis coefficients are set. In other words, to regard the controller as a black box, we need to know only the input-to-output ratio, and detailed modeling is not required. This simplicity allows our system to be easily embedded in applications. Our method using the pre-emphasis technique for a motion-blur compensation system and the experiment conducted to evaluate the method are explained.

We propose a method to extend the corresponding frequency by using a pre-emphasis technique. This method compensates for the gain reduction of a galvanometer mirror in sine-wave path tracking using proportional-integral-differential control.

Galvanometer mirrors are used for optical applications such as target tracking, drawing, and scanning control because of their high speed and accuracy. ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

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Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared on transparent membranes which are very fragile and difficult to manipulate. We present processes for the fabrication of samples with magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for Lorentz transmission electron microscopy and magnetic transmission x-ray microscopy studies. The samples are prepared on silicon nitride membranes and the fabrication consists of a spin coating, UV and electron-beam lithography, the chemical development of the resist, and the evaporation of the magnetic material followed by a lift-off process forming the final magnetic structures. The samples for the Lorentz transmission electron microscopy consist of magnetic nanodiscs prepared in a single lithography step. The samples for the magnetic x-ray transmission microscopy are used for time-resolved magnetization dynamic experiments, and magnetic nanodiscs are placed on a waveguide which is used for the generation of repeatable magnetic field pulses by passing an electric current through the waveguide. The waveguide is created in an extra lithography step.

A protocol for the fabrication of magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for transmission electron microscopy (TEM) and magnetic transmission x-ray microscopy (MTXM) studies is presented.

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared ...

Simultaneous Measurement of Turbulence and Particle Kinematics Using Flow Imaging Techniques

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine micro-organisms, and/or sediments in the ocean, or fluidized bed reactors and combustion processes in engineered systems. In order to study the effect of turbulence on the kinematics of particles in such flows, simultaneous measurements of both the flow and particle kinematics are required. Non-intrusive, optical flow measurement techniques for measuring turbulence, or for tracking particles, exist but measuring both simultaneously can be challenging due to interference between the techniques. The method presented herein provides a low cost and relatively simple method to make simultaneous measurements of the flow and particle kinematics. A cross section of the flow is measured using a particle image velocimetry (PIV) technique, which provides two components of velocity in the measurement plane. This technique utilizes a pulsed-laser for illumination of the seeded flow field that is imaged by a digital camera. The particle kinematics are simultaneously imaged using a light emitting diode (LED) line light that illuminates a planar cross section of the flow that overlaps with the PIV field-of-view (FOV). The line light is of low enough power that it does not affect the PIV measurements, but powerful enough to illuminate the larger particles of interest imaged using the high-speed camera. High-speed images that contain the laser pulses from the PIV technique are easily filtered by examining the summed intensity level of each high-speed image. By making the frame rate of the high-speed camera incommensurate with that of the PIV camera frame rate, the number of contaminated frames in the high-speed time series can be minimized. The technique is suitable for mean flows that are predominantly two-dimensional, contain particles that are at least 5 times the mean diameter of the PIV seeding tracers, and are low in concentration.

The technique described herein offers a low cost and relatively simple method to simultaneously measure particle kinematics and turbulence in flows with low particle concentrations. The turbulence is measured using particle image velocimetry (PIV), and particle kinematics are calculated from images obtained with a high-speed camera in an overlapping field-of-view.

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine ...

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a result, these platforms have not been fully exploited for direct observation of high-pressure transport in fractures. This work introduces microfluidic platforms that enable direct observation of multiphase flow in devices featuring surrogate permeable media and fractured systems. Such platforms provide a pathway to address important and timely questions such as those related to CO2 capture, utilization and storage. This work provides a detailed description of the fabrication techniques and an experimental setup that may serve to analyze the behavior of supercritical CO2 (scCO2) foam, its structure and stability. Such studies provide important insights regarding enhanced oil recovery processes and the role of hydraulic fractures in resource recovery from unconventional reservoirs. This work presents a comparative study of microfluidic devices developed using two different techniques: photolithography/wet-etching/thermal-bonding versus Selective Laser-induced Etching. Both techniques result in devices that are chemically and physically resistant and tolerant of high pressure and temperature conditions that correspond to subsurface systems of interest. Both techniques provide pathways to high-precision etched microchannels and capable lab-on-chip devices. Photolithography/wet-etching, however, enables fabrication of complex channel networks with complex geometries, which would be a challenging task for laser etching techniques. This work summarizes a step-by-step photolithography, wet-etching and glass thermal-bonding protocol and, presents representative observations of foam transport with relevance to oil recovery from unconventional tight and shale formations. Finally, this work describes the use of a high-resolution monochromatic sensor to observe scCO2 foam behavior where the entirety of the permeable medium is observed simultaneously while preserving the resolution needed to resolve features as small as 10 &#181;m.

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

This paper describes a protocol along with a comparative study of two microfluidic fabrication techniques, namely photolithography/wet-etching/thermal-bonding and Selective Laser-induced Etching (SLE), that are suitable for high-pressure conditions. These techniques constitute enabling platforms for direct observation of fluid flow in surrogate permeable media and fractured systems under reservoir conditions.

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a ...