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Laser absorption spectroscopy for gas sensing basically employs an air pump located at the gas cell probe to draw in ambient gases, and the on-site gas sample is subsequently delivered for laboratory non-real-time analysis. In this study, an in situ all-fiber remote gas sensing strategy is proposed. The anti-resonant hollow-core fiber (AR-HCF) is used as the sensing fiber, and a 20 m middle-hole eccentric-core fiber (MH-ECF) is used as the conducting fiber. The remote ambient gases can be inhaled into the AR-HCF as a result of the negative pressure transmitted through the MH-ECF when pumping gas at the interface of the MH-ECF. Since the real-time monitoring of greenhouse gas emissions in industrial processes holds immense significance in addressing global climate change, the detection of CO2 is achieved with the TDLAS-WMS method, and the gas sensing performance of an all-fiber remote gas sensing structure (RGS) is experimentally validated. The response time t90 under the pumping condition is about 456 s, which is about 30 times faster than that of free diffusion. Allan deviation results for more than one hour of continuous monitoring indicate that the lowest detection limit for the all-fiber RGS is 0.0373% when the integration time is 184 s. The all-fiber remote gas sensing strategy also possesses the benefits of being applicable to multiplex, hazardous gas environment passive monitoring., QC 20240515

This paper is devoted to mathematical modeling and computational experiments of a flow with negative pressure. A previously unknown class of fluid flow under the action of counter-current centrifugal forces is in focus. Volumetric forces in a non-conducting fluid can arise from gravity, vibrations, or rotations. In this paper, we consider controlled variable volumetric forces in a system with two rotations around the vertical axis and the tangential axis of a horizontal disk rotating around the vertical axis. The study of the coordinate system during double rotation showed that the double rotation about two perpendicular axes, one of which moves along a tangential direction to the rotating horizontal disk, is equal to the rotation around the oscillating axis inclined at some angle to the vertical axis., QC 20240229

Objective: To conduct a review of the literature on the effec-tiveness of negative pressure therapy in diabetic foot ulcers. Method: A review of the literature was carried out by con-sulting the electronic databases of PubMed, Lilacs, CENTRAL, WoS and SciELO. The risk of bias of the included studies was assessed using the Cochrane Handbook tool. Results: The total number of participants was 614 from a total of five randomized controlled clinical trials. Negative pressure therapy is effective in diabetic foot ulcers. Conclusions: Negative pressure therapy reduces the size of the diabetic foot ulcer, decreases closure time, and accel-erates healing by producing greater formation of granulation tissue. With this therapy, fewer dressing changes are needed, and the reparative processes are faster than stand-ard care., Objetivo: Realizar una revisión de la literatura sobre la eficacia de la terapia de presión negativa en úlceras de pie diabético. Método: Se elaboró una revisión de la literatura consultando las bases de datos electrónicas de PubMed, Lilacs, CENTRAL, WoS y SciELO. El riesgo de sesgo de los estu-dios incluidos se evaluó usando la herramienta del Manual Cochrane. Resultados: El número total de participantes fue de 614 de un total de cinco ensayos clínicos aleatorizados y controla-dos. La terapia de presión negativa fue eficaz en las úlceras de pie diabético. Conclusiones: La terapia de presión negativa reduce el tamaño de la úlcera de pie diabético, disminuye el tiempo de cierre, y acelera la curación produciendo mayor formación de tejido de granulación. Con esta terapia se necesitan me-nos cambios de apósitos, y presenta mayor rapidez de los procesos reparativos que la atención estándar.

In recent years, particle methods, which are good for moving boundary problems, have become an effective approach to understand and predict flows in complex geometry, such as lubrication behaviors in rolling bearings. This study adopted a physically consistent particle method, i.e., the moving particle hydrodynamics for incompressible flows (MPH-I) method. For capturing the free surface flows in lubrication, a surface tension model was included. In order to maintain the physical consistency in the MPH-I method, the surface tension model expressed with the two density potentials, which are cohesive pressure potential (CPP) and density gradient potential (DGP), was adopted. The MPH-I method with the two-potential-based surface tension model enabled to handle negative pressure and nearly incompressible flow with very large bulk modulus. In fact, the MPH-I method could successfully reproduce fundamental pressure generation effects in the fluid film lubrication, i.e., the wedge film and squeeze film effects. Furthermore, the computed lubrication pressure agreed well with the experimental results and the classic prediction with Reynolds equation. This implies that the present numerical method was validated under the fluid film lubrication problems.

Biomechanical forces are known to regulate the biological behaviors of cells. Although negative pressure has been used for wound healing, it is still unknown about its role in regulating cell plasticity. We investigated whether negative pressure could induce the dedifferentiation of hepatocytes. Using a commercial device, we found that the exposure of primary human hepatocytes to −50 mmHg quickly induced the formation of stress fibers and obviously changed cell morphology in 72 h. Moreover, the exposure of hepatocytes to −50 mmHg significantly upregulated RhoA, ROCK1, and ROCK2 in 1–6 h, and dramatically enhanced the expression of marker molecules on “stemness”, such as OCT4, SOX2, KLF4, MYC, NANOG, and CD133 in 6–72 h. However, all these changes in hepatocytes induced by −50 mmHg stimulation were almost abrogated by ROCK inhibitor Y27623. Our data suggest that an appropriate force of negative pressure stimulation can effectively induce the dedifferentiation of hepatocytes via RhoA/ROCK pathway activation., Biochemical and Biophysical Research Communications, 667, pp.104-110; 2023

Biomechanical forces are known to regulate the biological behaviors of cells. Although negative pressure has been used for wound healing, it is still unknown about its role in regulating cell plasticity. We investigated whether negative pressure could induce the dedifferentiation of hepatocytes. Using a commercial device, we found that the exposure of primary human hepatocytes to −50 mmHg quickly induced the formation of stress fibers and obviously changed cell morphology in 72 h. Moreover, the exposure of hepatocytes to −50 mmHg significantly upregulated RhoA, ROCK1, and ROCK2 in 1–6 h, and dramatically enhanced the expression of marker molecules on “stemness”, such as OCT4, SOX2, KLF4, MYC, NANOG, and CD133 in 6–72 h. However, all these changes in hepatocytes induced by −50 mmHg stimulation were almost abrogated by ROCK inhibitor Y27623. Our data suggest that an appropriate force of negative pressure stimulation can effectively induce the dedifferentiation of hepatocytes via RhoA/ROCK pathway activation., Biochemical and Biophysical Research Communications, 667, pp.104-110; 2023

Microvascular fluid exchange is primarily dependent on Starling forces and both the active and passive myogenic response of arterioles and post-capillary venules. Arterioles are classically considered resistance vessels, while venules are considered capacitance vessels with high distensibility and low tonic sympathetic stimulation at rest. However, few studies have investigated the effects of modulating interstitial hydrostatic pressure, particularly in the context of hemorrhagic shock. The objective of this study was to investigate the mechanics of arterioles and functional capillary density (FCD) during application of negative tissue interstitial pressure after 40% total blood volume hemorrhagic shock. In this study, we characterized systemic and microcirculatory hemodynamic parameters, including FCD, in hamsters instrumented with a dorsal window chamber and a custom-designed negative pressure application device via intravital microscopy. In large arterioles, application of negative pressure after hemorrhagic shock resulted in a 13 ± 11% decrease in flow compared with only a 7 ± 9% decrease in flow after hemorrhagic shock alone after 90 minutes. In post-capillary venules, however, application of negative pressure after hemorrhagic shock resulted in a 31 ± 4% decrease in flow compared with only an 8 ± 5% decrease in flow after hemorrhagic shock alone after 90 minutes. Normalized FCD was observed to significantly improve after application of negative pressure after hemorrhagic shock (0.66 ± 0.02) compared to hemorrhagic shock without application of negative pressure (0.50 ± 0.04). Our study demonstrates that application of negative pressure acutely improves FCD during hemorrhagic shock, though it does not normalize FCD. These results suggest that by increasing the hydrostatic pressure gradient between the microvasculature and interstitium, microvascular perfusion can be transiently restored in the absence of volume resuscitation. This study has significant clinical

There has been a growing body of evidence that impaired microvascular perfusion is an indicator for mortality in critical patients. However, there are limited clinical microvascular therapeutics targets. The objective of this thesis is to investigate and intervene upon microvascular disease found in hemorrhagic shock, neoplasia, and inflammation concurrent with acute respiratory distress (ARDS). Chapter one of this thesis focuses on engineering an intervention to improve microvascular perfusion by leveraging the Starling forces in capillaries. Specifically, we designed and implemented a device for the application of negative pressure to reduce tissue interstitial pressure, which transiently increased functional capillary density after hemorrhagic shock, a known metric for microvascular perfusion, without the need for volume resuscitation. Chapter two aims on engineering red blood cells to target the tumor microcirculation and microenvironment. Specifically, we studied red blood cells as a delivery vehicle for RRx-001, an anti-cancer agent, and altered their biomechanics, by selectively inducing tumor adhesion in the tumor microenvironment. This increase in adhesion had an anti-neoplastic effect, with our study showing a 40% decrease in tumor size. In chapter three, we engineered a new intervention for altering microvascular inflammation as seen in the acute respiratory distress syndrome (ARDS). Specifically, we aerosolized Nitric Oxide releasing nanoparticles (NO-nps) to mice suffering of ARDS and found a reduction in peripheral neutrophils, indicative of reduced inflammation. As demonstrated, engineering interventions to improve microvascular perfusion shows great potential as a therapeutic target for a broad range of pathophysiologies, including hemorrhagic shock, cancer, and ARDS.

There has been a growing body of evidence that impaired microvascular perfusion is an indicator for mortality in critical patients. However, there are limited clinical microvascular therapeutics targets. The objective of this thesis is to investigate and intervene upon microvascular disease found in hemorrhagic shock, neoplasia, and inflammation concurrent with acute respiratory distress (ARDS). Chapter one of this thesis focuses on engineering an intervention to improve microvascular perfusion by leveraging the Starling forces in capillaries. Specifically, we designed and implemented a device for the application of negative pressure to reduce tissue interstitial pressure, which transiently increased functional capillary density after hemorrhagic shock, a known metric for microvascular perfusion, without the need for volume resuscitation. Chapter two aims on engineering red blood cells to target the tumor microcirculation and microenvironment. Specifically, we studied red blood cells as a delivery vehicle for RRx-001, an anti-cancer agent, and altered their biomechanics, by selectively inducing tumor adhesion in the tumor microenvironment. This increase in adhesion had an anti-neoplastic effect, with our study showing a 40% decrease in tumor size. In chapter three, we engineered a new intervention for altering microvascular inflammation as seen in the acute respiratory distress syndrome (ARDS). Specifically, we aerosolized Nitric Oxide releasing nanoparticles (NO-nps) to mice suffering of ARDS and found a reduction in peripheral neutrophils, indicative of reduced inflammation. As demonstrated, engineering interventions to improve microvascular perfusion shows great potential as a therapeutic target for a broad range of pathophysiologies, including hemorrhagic shock, cancer, and ARDS.

Background Vacuum-assisted closure (VAC) is the new arsenal that could aid in managing acute and chronic wounds. Vacuum assisted closure also called negative pressure wound therapy is a procedure where one would use vacuum to enhance wound healing. Objectives To review the role of VAC in wound healing. Methodology: It was a prospective study among patients admitted to the department of ulcer with chronic non healing ulcer. The study period was between October 2012 to September 2021. 50 participants were enrolled into the study. The data collected were entered into Microsoft excel 2019 and the excel was then loaded into SPSS version 23 for further analysis. Results: The wound healing was found to be better from day 3 to day 7 and from day 7 to day 10. There was significant positive change in wound healing with P value of less than 0.05. The healing was not found to be associated with any other factor. Conclusion: Vacuum assisted closure would aid in wound healing among the patients with chronic non-healing ulcer.

Background Vacuum-assisted closure (VAC) is the new arsenal that could aid in managing acute and chronic wounds. Vacuum assisted closure also called negative pressure wound therapy is a procedure where one would use vacuum to enhance wound healing. Objectives To review the role of VAC in wound healing. Methodology: It was a prospective study among patients admitted to the department of ulcer with chronic non healing ulcer. The study period was between October 2012 to September 2021. 50 participants were enrolled into the study. The data collected were entered into Microsoft excel 2019 and the excel was then loaded into SPSS version 23 for further analysis. Results: The wound healing was found to be better from day 3 to day 7 and from day 7 to day 10. There was significant positive change in wound healing with P value of less than 0.05. The healing was not found to be associated with any other factor. Conclusion: Vacuum assisted closure would aid in wound healing among the patients with chronic non-healing ulcer.

Background Vacuum-assisted closure (VAC) is the new arsenal that could aid in managing acute and chronic wounds. Vacuum assisted closure also called negative pressure wound therapy is a procedure where one would use vacuum to enhance wound healing. Objectives To review the role of VAC in wound healing. Methodology: It was a prospective study among patients admitted to the department of ulcer with chronic non healing ulcer. The study period was between October 2012 to September 2021. 50 participants were enrolled into the study. The data collected were entered into Microsoft excel 2019 and the excel was then loaded into SPSS version 23 for further analysis. Results: The wound healing was found to be better from day 3 to day 7 and from day 7 to day 10. There was significant positive change in wound healing with P value of less than 0.05. The healing was not found to be associated with any other factor. Conclusion: Vacuum assisted closure would aid in wound healing among the patients with chronic non-healing ulcer.

Background Vacuum-assisted closure (VAC) is the new arsenal that could aid in managing acute and chronic wounds. Vacuum assisted closure also called negative pressure wound therapy is a procedure where one would use vacuum to enhance wound healing. Objectives To review the role of VAC in wound healing. Methodology: It was a prospective study among patients admitted to the department of ulcer with chronic non healing ulcer. The study period was between October 2012 to September 2021. 50 participants were enrolled into the study. The data collected were entered into Microsoft excel 2019 and the excel was then loaded into SPSS version 23 for further analysis. Results: The wound healing was found to be better from day 3 to day 7 and from day 7 to day 10. There was significant positive change in wound healing with P value of less than 0.05. The healing was not found to be associated with any other factor. Conclusion: Vacuum assisted closure would aid in wound healing among the patients with chronic non-healing ulcer.

There has been a growing body of evidence that impaired microvascular perfusion is an indicator for mortality in critical patients. However, there are limited clinical microvascular therapeutics targets. The objective of this thesis is to investigate and intervene upon microvascular disease found in hemorrhagic shock, neoplasia, and inflammation concurrent with acute respiratory distress (ARDS). Chapter one of this thesis focuses on engineering an intervention to improve microvascular perfusion by leveraging the Starling forces in capillaries. Specifically, we designed and implemented a device for the application of negative pressure to reduce tissue interstitial pressure, which transiently increased functional capillary density after hemorrhagic shock, a known metric for microvascular perfusion, without the need for volume resuscitation. Chapter two aims on engineering red blood cells to target the tumor microcirculation and microenvironment. Specifically, we studied red blood cells as a delivery vehicle for RRx-001, an anti-cancer agent, and altered their biomechanics, by selectively inducing tumor adhesion in the tumor microenvironment. This increase in adhesion had an anti-neoplastic effect, with our study showing a 40% decrease in tumor size. In chapter three, we engineered a new intervention for altering microvascular inflammation as seen in the acute respiratory distress syndrome (ARDS). Specifically, we aerosolized Nitric Oxide releasing nanoparticles (NO-nps) to mice suffering of ARDS and found a reduction in peripheral neutrophils, indicative of reduced inflammation. As demonstrated, engineering interventions to improve microvascular perfusion shows great potential as a therapeutic target for a broad range of pathophysiologies, including hemorrhagic shock, cancer, and ARDS.

Microvascular fluid exchange is primarily dependent on Starling forces and both the active and passive myogenic response of arterioles and post-capillary venules. Arterioles are classically considered resistance vessels, while venules are considered capacitance vessels with high distensibility and low tonic sympathetic stimulation at rest. However, few studies have investigated the effects of modulating interstitial hydrostatic pressure, particularly in the context of hemorrhagic shock. The objective of this study was to investigate the mechanics of arterioles and functional capillary density (FCD) during application of negative tissue interstitial pressure after 40% total blood volume hemorrhagic shock. In this study, we characterized systemic and microcirculatory hemodynamic parameters, including FCD, in hamsters instrumented with a dorsal window chamber and a custom-designed negative pressure application device via intravital microscopy. In large arterioles, application of negative pressure after hemorrhagic shock resulted in a 13 ± 11% decrease in flow compared with only a 7 ± 9% decrease in flow after hemorrhagic shock alone after 90 minutes. In post-capillary venules, however, application of negative pressure after hemorrhagic shock resulted in a 31 ± 4% decrease in flow compared with only an 8 ± 5% decrease in flow after hemorrhagic shock alone after 90 minutes. Normalized FCD was observed to significantly improve after application of negative pressure after hemorrhagic shock (0.66 ± 0.02) compared to hemorrhagic shock without application of negative pressure (0.50 ± 0.04). Our study demonstrates that application of negative pressure acutely improves FCD during hemorrhagic shock, though it does not normalize FCD. These results suggest that by increasing the hydrostatic pressure gradient between the microvasculature and interstitium, microvascular perfusion can be transiently restored in the absence of volume resuscitation. This study has significant clinical

Helium implantation in epitaxial thin films is a way to control the out-of-plane deformation independently from the in-plane strain controlled by epitaxy. In particular, implantation by means of a helium microscope allows for local implantation and patterning down to the nanometer resolution, which is of interest for device applications. We present here a study of bismuth ferrite (BiFeO3) films where strain was patterned locally by helium implantation. Our combined Raman, x-ray diffraction, and transmission electron microscopy (TEM) study shows that the implantation causes an elongation of the BiFeO3 unit cell and ultimately a transition towards the so-called supertetragonal polymorph via states with mixed phases. In addition, TEM reveals the onset of amorphization at a threshold dose that does not seem to impede the overall increase in tetragonality. The phase transition from the R-like to T-like BiFeO3 appears as first-order in character, with regions of phase coexistence and abrupt changes in lattice parameters.

Helium implantation in epitaxial thin films is a way to control the out-of-plane deformation independently from the in-plane strain controlled by epitaxy. In particular, implantation by means of a helium microscope allows for local implantation and patterning down to the nanometer resolution, which is of interest for device applications. We present here a study of bismuth ferrite (BiFeO3) films where strain was patterned locally by helium implantation. Our combined Raman, x-ray diffraction, and transmission electron microscopy (TEM) study shows that the implantation causes an elongation of the BiFeO3 unit cell and ultimately a transition towards the so-called supertetragonal polymorph via states with mixed phases. In addition, TEM reveals the onset of amorphization at a threshold dose that does not seem to impede the overall increase in tetragonality. The phase transition from the R-like to T-like BiFeO3 appears as first-order in character, with regions of phase coexistence and abrupt changes in lattice parameters.

Background Vacuum-assisted closure (VAC) is the new arsenal that could aid in managing acute and chronic wounds. Vacuum assisted closure also called negative pressure wound therapy is a procedure where one would use vacuum to enhance wound healing. Objectives To review the role of VAC in wound healing. Methodology: It was a prospective study among patients admitted to the department of ulcer with chronic non healing ulcer. The study period was between October 2012 to September 2021. 50 participants were enrolled into the study. The data collected were entered into Microsoft excel 2019 and the excel was then loaded into SPSS version 23 for further analysis. Results: The wound healing was found to be better from day 3 to day 7 and from day 7 to day 10. There was significant positive change in wound healing with P value of less than 0.05. The healing was not found to be associated with any other factor. Conclusion: Vacuum assisted closure would aid in wound healing among the patients with chronic non-healing ulcer.

Background Vacuum-assisted closure (VAC) is the new arsenal that could aid in managing acute and chronic wounds. Vacuum assisted closure also called negative pressure wound therapy is a procedure where one would use vacuum to enhance wound healing. Objectives To review the role of VAC in wound healing. Methodology: It was a prospective study among patients admitted to the department of ulcer with chronic non healing ulcer. The study period was between October 2012 to September 2021. 50 participants were enrolled into the study. The data collected were entered into Microsoft excel 2019 and the excel was then loaded into SPSS version 23 for further analysis. Results: The wound healing was found to be better from day 3 to day 7 and from day 7 to day 10. There was significant positive change in wound healing with P value of less than 0.05. The healing was not found to be associated with any other factor. Conclusion: Vacuum assisted closure would aid in wound healing among the patients with chronic non-healing ulcer.

Background Vacuum-assisted closure (VAC) is the new arsenal that could aid in managing acute and chronic wounds. Vacuum assisted closure also called negative pressure wound therapy is a procedure where one would use vacuum to enhance wound healing. Objectives To review the role of VAC in wound healing. Methodology: It was a prospective study among patients admitted to the department of ulcer with chronic non healing ulcer. The study period was between October 2012 to September 2021. 50 participants were enrolled into the study. The data collected were entered into Microsoft excel 2019 and the excel was then loaded into SPSS version 23 for further analysis. Results: The wound healing was found to be better from day 3 to day 7 and from day 7 to day 10. There was significant positive change in wound healing with P value of less than 0.05. The healing was not found to be associated with any other factor. Conclusion: Vacuum assisted closure would aid in wound healing among the patients with chronic non-healing ulcer.

Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The disease spreads primarily through respiratory droplets, physical contact and contact with surfaces as well as fomites. Isolation of patients in hospitals and quarantine of contacts in separate facilities are the mainstay of outbreak containment. This pandemic has brought forward various challenges to the hospital administrators, one of the most important being air-conditioning of hospitals in the time of this pandemic.

Background Vacuum-assisted closure (VAC) is the new arsenal that could aid in managing acute and chronic wounds. Vacuum assisted closure also called negative pressure wound therapy is a procedure where one would use vacuum to enhance wound healing. Objectives To review the role of VAC in wound healing. Methodology: It was a prospective study among patients admitted to the department of ulcer with chronic non healing ulcer. The study period was between October 2012 to September 2021. 50 participants were enrolled into the study. The data collected were entered into Microsoft excel 2019 and the excel was then loaded into SPSS version 23 for further analysis. Results: The wound healing was found to be better from day 3 to day 7 and from day 7 to day 10. There was significant positive change in wound healing with P value of less than 0.05. The healing was not found to be associated with any other factor. Conclusion: Vacuum assisted closure would aid in wound healing among the patients with chronic non-healing ulcer.

Objective: To report a case about the use of the Negative-pressure wound therapy as an alternative treatment for arterial vascular ulcers presented in the lower limbs.  Methods: The patient’s records were reviewed based on her medical history in a tertiary referral care center in Popayan, Colombia. Subsequently, a systematic literature review was conducted through the Pubmed database, ScienceDirect, and Scielo. Results: The use of  Negative-pressure wound therapy favored the lesion healing process. Conclusions: Nowadays, this system is considered as an essential treatment for complex wounds, which represent a major therapeutic challenge., Objetivo: Reportar un caso sobre el uso de la terapia de presión negativa como tratamiento alternativo en el manejo de una úlcera vascular arterial de miembros inferiores. Métodos: Por medio de la historia clínica, se revisó los registros previos de una paciente en un centro de atención médica de tercer nivel en Popayán, Colombia. Posteriormente, se realizó una revisión sistemática bibliográfica a través de las bases de datos de Pubmed, ScienceDirect y Scielo. Resultados: La terapia de presión negativa favoreció el proceso de cicatrización, permitiendo el cierre de la herida. Conclusiones: Actualmente, este sistema se considera un apoyo fundamental en el tratamiento de las heridas complejas, las cuales suponen un reto terapéutico importante.

Objective: To report a case about the use of the Negative-pressure wound therapy as an alternative treatment for arterial vascular ulcers presented in the lower limbs.  Methods: The patient’s records were reviewed based on her medical history in a tertiary referral care center in Popayan, Colombia. Subsequently, a systematic literature review was conducted through the Pubmed database, ScienceDirect, and Scielo. Results: The use of  Negative-pressure wound therapy favored the lesion healing process. Conclusions: Nowadays, this system is considered as an essential treatment for complex wounds, which represent a major therapeutic challenge., Objetivo: Reportar un caso sobre el uso de la terapia de presión negativa como tratamiento alternativo en el manejo de una úlcera vascular arterial de miembros inferiores. Métodos: Por medio de la historia clínica, se revisó los registros previos de una paciente en un centro de atención médica de tercer nivel en Popayán, Colombia. Posteriormente, se realizó una revisión sistemática bibliográfica a través de las bases de datos de Pubmed, ScienceDirect y Scielo. Resultados: La terapia de presión negativa favoreció el proceso de cicatrización, permitiendo el cierre de la herida. Conclusiones: Actualmente, este sistema se considera un apoyo fundamental en el tratamiento de las heridas complejas, las cuales suponen un reto terapéutico importante.

Objective: To report a case about the use of the Negative-pressure wound therapy as an alternative treatment for arterial vascular ulcers presented in the lower limbs.  Methods: The patient’s records were reviewed based on her medical history in a tertiary referral care center in Popayan, Colombia. Subsequently, a systematic literature review was conducted through the Pubmed database, ScienceDirect, and Scielo. Results: The use of  Negative-pressure wound therapy favored the lesion healing process. Conclusions: Nowadays, this system is considered as an essential treatment for complex wounds, which represent a major therapeutic challenge., Objetivo: Reportar un caso sobre el uso de la terapia de presión negativa como tratamiento alternativo en el manejo de una úlcera vascular arterial de miembros inferiores. Métodos: Por medio de la historia clínica, se revisó los registros previos de una paciente en un centro de atención médica de tercer nivel en Popayán, Colombia. Posteriormente, se realizó una revisión sistemática bibliográfica a través de las bases de datos de Pubmed, ScienceDirect y Scielo. Resultados: La terapia de presión negativa favoreció el proceso de cicatrización, permitiendo el cierre de la herida. Conclusiones: Actualmente, este sistema se considera un apoyo fundamental en el tratamiento de las heridas complejas, las cuales suponen un reto terapéutico importante.

No abstract

The presented work investigates the potential of utilizing commercially available Electric Ducted Fans (EDFs) as adhesion actuators, while providing a novel insight on the analysis of the adhesion nature related to negative pressure and thrust force generation against a target surface. To this goal, a novel EDF-based Vortex Actuation Setup (VAS) is proposed for monitoring important properties such as adhesion force, pressure distribution, current draw, motor temperature etc. during the VAS’ operation when placed in variable distances from a test surface. In addition, this work is contributing towards the novel evaluation of different design variables and modifications to original EDF structures, with the goal of analyzing their effect on the prototype VAS, while optimizing its adhesion efficiency for its future incorporation in a wall-climbing robot for inspection and repair purposes., Validerad;2019;Nivå 2;2019-08-22 (johcin), FET-OPEN "CompInnova"

The presented work investigates the potential of utilizing commercially available Electric Ducted Fans (EDFs) as adhesion actuators, while providing a novel insight on the analysis of the adhesion nature related to negative pressure and thrust force generation against a target surface. To this goal, a novel EDF-based Vortex Actuation Setup (VAS) is proposed for monitoring important properties such as adhesion force, pressure distribution, current draw, motor temperature etc. during the VAS’ operation when placed in variable distances from a test surface. In addition, this work is contributing towards the novel evaluation of different design variables and modifications to original EDF structures, with the goal of analyzing their effect on the prototype VAS, while optimizing its adhesion efficiency for its future incorporation in a wall-climbing robot for inspection and repair purposes., Validerad;2019;Nivå 2;2019-08-22 (johcin), FET-OPEN "CompInnova"

The presented work investigates the potential of utilizing commercially available Electric Ducted Fans (EDFs) as adhesion actuators, while providing a novel insight on the analysis of the adhesion nature related to negative pressure and thrust force generation against a target surface. To this goal, a novel EDF-based Vortex Actuation Setup (VAS) is proposed for monitoring important properties such as adhesion force, pressure distribution, current draw, motor temperature etc. during the VAS’ operation when placed in variable distances from a test surface. In addition, this work is contributing towards the novel evaluation of different design variables and modifications to original EDF structures, with the goal of analyzing their effect on the prototype VAS, while optimizing its adhesion efficiency for its future incorporation in a wall-climbing robot for inspection and repair purposes., Validerad;2019;Nivå 2;2019-08-22 (johcin), FET-OPEN "CompInnova"

The interaction of a blast wave propagating in air with different fluids like water column, aqueous foam and thermal/density inhomogeneity have been studied both experimentally and numerically. The blast waves were generated at atmospheric conditions in a newly constructed exploding wire facility. For fixed capacitance and wire size, the intensity of the shock front (measured typically at 200 mm from the wire explosion plane) was varied by controlling the charges stored in the capacitor and the size of the test section. Qualitative features of the interaction were captured using shadowgraph technique. Numerical simulations were performed to better analyze and understand the flow features observed in experiments. The main points across each fluid interactions are as follow: Water column: A new technique was implemented to create highly repeatable, properly shaped, large diameter water column. The impact of a blast wave with shock Mach number ranging from 1.75 to 2.4 on a 22 mm diameter water column resulted in a complex system of waves propagating inside the column. Due to the concave boundary of the downstream interface, the reflected expansion wave naturally focused at a point before travelling upstream resulting in the generation of large negative pressures leading to nucleation of cavitation bubbles. Through high speed photography, various aspects of the flow features were discussed qualitatively and quantitatively. With the aid of numerical simulation, the effect of size of water column and shock strength on the maximum attainable negative pressures in the absence of cavitation were quantified. Aqueous foam: The performance of various aqueous foam barrier configurations on the attenuation of externally generated blast wave peak pressure was examined. Here a blast wave with shock Mach number 4.8 was allowed to interact with an aqueous foam barrier of initial liquid fraction 0.1. The dominant process responsible for reduction of peak pressure was the `catching up', QC 20180518

The interaction of a blast wave propagating in air with different fluids like water column, aqueous foam and thermal/density inhomogeneity have been studied both experimentally and numerically. The blast waves were generated at atmospheric conditions in a newly constructed exploding wire facility. For fixed capacitance and wire size, the intensity of the shock front (measured typically at 200 mm from the wire explosion plane) was varied by controlling the charges stored in the capacitor and the size of the test section. Qualitative features of the interaction were captured using shadowgraph technique. Numerical simulations were performed to better analyze and understand the flow features observed in experiments. The main points across each fluid interactions are as follow: Water column: A new technique was implemented to create highly repeatable, properly shaped, large diameter water column. The impact of a blast wave with shock Mach number ranging from 1.75 to 2.4 on a 22 mm diameter water column resulted in a complex system of waves propagating inside the column. Due to the concave boundary of the downstream interface, the reflected expansion wave naturally focused at a point before travelling upstream resulting in the generation of large negative pressures leading to nucleation of cavitation bubbles. Through high speed photography, various aspects of the flow features were discussed qualitatively and quantitatively. With the aid of numerical simulation, the effect of size of water column and shock strength on the maximum attainable negative pressures in the absence of cavitation were quantified. Aqueous foam: The performance of various aqueous foam barrier configurations on the attenuation of externally generated blast wave peak pressure was examined. Here a blast wave with shock Mach number 4.8 was allowed to interact with an aqueous foam barrier of initial liquid fraction 0.1. The dominant process responsible for reduction of peak pressure was the `catching up', QC 20180518

The interaction of a blast wave propagating in air with different fluids like water column, aqueous foam and thermal/density inhomogeneity have been studied both experimentally and numerically. The blast waves were generated at atmospheric conditions in a newly constructed exploding wire facility. For fixed capacitance and wire size, the intensity of the shock front (measured typically at 200 mm from the wire explosion plane) was varied by controlling the charges stored in the capacitor and the size of the test section. Qualitative features of the interaction were captured using shadowgraph technique. Numerical simulations were performed to better analyze and understand the flow features observed in experiments. The main points across each fluid interactions are as follow: Water column: A new technique was implemented to create highly repeatable, properly shaped, large diameter water column. The impact of a blast wave with shock Mach number ranging from 1.75 to 2.4 on a 22 mm diameter water column resulted in a complex system of waves propagating inside the column. Due to the concave boundary of the downstream interface, the reflected expansion wave naturally focused at a point before travelling upstream resulting in the generation of large negative pressures leading to nucleation of cavitation bubbles. Through high speed photography, various aspects of the flow features were discussed qualitatively and quantitatively. With the aid of numerical simulation, the effect of size of water column and shock strength on the maximum attainable negative pressures in the absence of cavitation were quantified. Aqueous foam: The performance of various aqueous foam barrier configurations on the attenuation of externally generated blast wave peak pressure was examined. Here a blast wave with shock Mach number 4.8 was allowed to interact with an aqueous foam barrier of initial liquid fraction 0.1. The dominant process responsible for reduction of peak pressure was the `catching up', QC 20180518

The interaction of a blast wave propagating in air with different fluids like water column, aqueous foam and thermal/density inhomogeneity have been studied both experimentally and numerically. The blast waves were generated at atmospheric conditions in a newly constructed exploding wire facility. For fixed capacitance and wire size, the intensity of the shock front (measured typically at 200 mm from the wire explosion plane) was varied by controlling the charges stored in the capacitor and the size of the test section. Qualitative features of the interaction were captured using shadowgraph technique. Numerical simulations were performed to better analyze and understand the flow features observed in experiments. The main points across each fluid interactions are as follow: Water column: A new technique was implemented to create highly repeatable, properly shaped, large diameter water column. The impact of a blast wave with shock Mach number ranging from 1.75 to 2.4 on a 22 mm diameter water column resulted in a complex system of waves propagating inside the column. Due to the concave boundary of the downstream interface, the reflected expansion wave naturally focused at a point before travelling upstream resulting in the generation of large negative pressures leading to nucleation of cavitation bubbles. Through high speed photography, various aspects of the flow features were discussed qualitatively and quantitatively. With the aid of numerical simulation, the effect of size of water column and shock strength on the maximum attainable negative pressures in the absence of cavitation were quantified. Aqueous foam: The performance of various aqueous foam barrier configurations on the attenuation of externally generated blast wave peak pressure was examined. Here a blast wave with shock Mach number 4.8 was allowed to interact with an aqueous foam barrier of initial liquid fraction 0.1. The dominant process responsible for reduction of peak pressure was the `catching up', QC 20180518

The interaction of a blast wave propagating in air with different fluids like water column, aqueous foam and thermal/density inhomogeneity have been studied both experimentally and numerically. The blast waves were generated at atmospheric conditions in a newly constructed exploding wire facility. For fixed capacitance and wire size, the intensity of the shock front (measured typically at 200 mm from the wire explosion plane) was varied by controlling the charges stored in the capacitor and the size of the test section. Qualitative features of the interaction were captured using shadowgraph technique. Numerical simulations were performed to better analyze and understand the flow features observed in experiments. The main points across each fluid interactions are as follow: Water column: A new technique was implemented to create highly repeatable, properly shaped, large diameter water column. The impact of a blast wave with shock Mach number ranging from 1.75 to 2.4 on a 22 mm diameter water column resulted in a complex system of waves propagating inside the column. Due to the concave boundary of the downstream interface, the reflected expansion wave naturally focused at a point before travelling upstream resulting in the generation of large negative pressures leading to nucleation of cavitation bubbles. Through high speed photography, various aspects of the flow features were discussed qualitatively and quantitatively. With the aid of numerical simulation, the effect of size of water column and shock strength on the maximum attainable negative pressures in the absence of cavitation were quantified. Aqueous foam: The performance of various aqueous foam barrier configurations on the attenuation of externally generated blast wave peak pressure was examined. Here a blast wave with shock Mach number 4.8 was allowed to interact with an aqueous foam barrier of initial liquid fraction 0.1. The dominant process responsible for reduction of peak pressure was the `catching up', QC 20180518

Introducción: Se analiza una muestra de 45 pacientes tratados en el Hospital General Universitario Gregorio Marañón (HGUGM) con diagnóstico común de «herida abdominal dehiscente con exposición de malla» y que cumplen los criterios de inclusión. El grupo denominado «VAC instilación» comprende 11 pacientes tratados con terapia por presión negativa con instilación intermitente (VAC Veraflo®); y el denominado «convencional» 34 pacientes manejados mediante tratamiento con curas convencionales. Objetivos: El objetivo del presente trabajo es determinar la efectividad y eficiencia de la mencionada terapia para la indicación y la población de pacientes descrita. Metodología: Para cada una de las variables del estudio se representan los valores observados para la totalidad de la muestra; y en segundo lugar, su distribución según grupos de tratamiento. Se analizan las diferencias entre ambos y su significación estadística para la extracción de conclusiones. Se presentan los estadísticos descriptivos de las variables del paciente como edad, sexo y comorbilidades; así como con los estadísticos descriptivos de las variables del tratamiento y de las variables de análisis como los episodios de hospitalización, cirugías adicionales, tiempo de hospitalización, y tiempo de tratamiento. Las variables cualitativas se expresan en valores de frecuencia y porcentajes, si bien dados los diferentes tamaños de los grupos a estudio, se priorizan los datos expresados en porcentajes del grupo para su interpretación. En el caso de variables cuantitativas, debido a la elevada dispersión de sus valores, se proporcionan las medianas y percentiles (25 y 75). Se realiza el contraste de hipótesis mediante las pruebas de χ2 y U de Mann-Whitney. Resultados: Ambos grupos de estudio resultan comparables en sus características demográficas. Globalmente se trata de una muestra de pacientes de edad avanzada, con múltiples comorbilidades y situada en el grupo de alto riesgo para complicaciones después de una c

Background: No definitive data about open abdomen (OA) epidemiology and outcomes exist. The World Society of Emergency Surgery (WSES) and the Panamerican Trauma Society (PTS) promoted the International Register of Open Abdomen (IROA). Methods: A prospective observational cohort study including patients with an OA treatment. Data were recorded on a web platform (Clinical Registers®) through a dedicated website: www.clinicalregisters.org. Results: Four hundred two patients enrolled. Adult patients: 369 patients; Mean age: 57.39±18.37; 56% male; Mean BMI: 36±5.6. OA indication: Peritonitis (48.7%), Trauma (20.5%), Vascular Emergencies/Hemorrhage (9.4%), Ischemia (9.1%), Pancreatitis (4.2%),Post-operative abdominal-compartment-syndrome (3.9%), Others (4.2%). The most adopted Temporary-abdominal-closure systems were the commercial negative pressure ones (44.2%). During OA 38% of patients had complications; among them 10.5% had fistula. Definitive closure: 82.8%; Mortality during treatment: 17.2%. Mean duration of OA: 5.39(±4.83) days; Mean number of dressing changes: 0.88(±0.88). After-closure complications: (49.5%) and Mortality: (9%). No significant associations among TACT, indications, mortality, complications and fistula. A linear correlationexists between days of OA and complications (Pearson linear correlation = 0.326 p<0.0001) and with the fistula development (Pearson = 0.146 p= 0.016). Pediatric patients: 33 patients. Mean age: 5.91±(3.68) years; 60% male. Mortality: 3.4%; Complications: 44.8%; Fistula: 3.4%. Mean duration of OA: 3.22(±3.09) days. Conclusion: Temporary abdominal closure is reliable and safe. The different techniques account for different results according to the different indications. In peritonitis commercial negative pressure temporary closure seems to improve results. In trauma skin-closure and Bogotà-bag seem to improve results. Trial registration: ClinicalTrials.gov NCT02382770

OBJECTIVE: To describe for the first time in literature the specific methodology of use of negative pressure wound therapy (NPWT) for duodenal fistula through clinical cases. The constant increase of use of NPWT for complex surgical situations imposes tailored previously undescribed solutions for the technique.PATIENTS AND METHODS: Herein, three cases of high output duodenal fistula successfully treated with Negative Pressure Wound Therapy (NPWT) are reported. The technical details for the application of NPWT to these fistulas are discussed and described.RESULTS: All three patients recovered without the necessity of further surgical operations.CONCLUSIONS: When using NPWT, management of high-output duodenal fistulas must rely on some degree of customization of the aspiration systems. The aim of the procedure is to put under depression the duodenal hole and surrounding tissues "all in one" and not to separate the complex wound in sectors as usually indicated. We suggest calling this technique Negative Pressure Fistula Therapy.

The pododermatitis interacts directly with the animal welfare, it is a disease that alters the behavior, causing serious discomfort to the animals and is also a port for incoming pathogens, being the legs constantly on the chickens litter. We collected data of male and female chicken's feet with 14, 28 and 42 days of age, in four negative pressures poultry (A, B, C and D) with controlled temperature, either of the coolers side and of the exhausters side, totaling 144 birds in hot season in Brazil and 144 birds in cold season in Spain, applying an evaluation of injury scores of 1-4. Males and females showed no significant differences in any country, although the media in Brazil were higher. In Spain the aviary A showed higher scores of injuries and in Brazil there was no significant difference in any aviary. Regarding ages, in animals with 28 and 42 days, the lesions were significantly bigger than 14 days in both countries. The scores on hand showed significant differences only for the media in Brazil, which were higher than that of Spain. Being the area of the coolers more wet, this indicates that it may increase the injury index, with the aggravation of the external temperature and relative humidity of the air higher in Brazil. We conclude that the external ambience influences the internal ambience and added to the management and reuse of the litter may interfere in increasing injury score as the birds gain more weight. Keywords: cushion plant lesion, contact dermatitis, negative pressure, ambience.

The pododermatitis interacts directly with the animal welfare, it is a disease that alters the behavior, causing serious discomfort to the animals and is also a port for incoming pathogens, being the legs constantly on the chickens litter. We collected data of male and female chicken's feet with 14, 28 and 42 days of age, in four negative pressures poultry (A, B, C and D) with controlled temperature, either of the coolers side and of the exhausters side, totaling 144 birds in hot season in Brazil and 144 birds in cold season in Spain, applying an evaluation of injury scores of 1-4. Males and females showed no significant differences in any country, although the media in Brazil were higher. In Spain the aviary A showed higher scores of injuries and in Brazil there was no significant difference in any aviary. Regarding ages, in animals with 28 and 42 days, the lesions were significantly bigger than 14 days in both countries. The scores on hand showed significant differences only for the media in Brazil, which were higher than that of Spain. Being the area of the coolers more wet, this indicates that it may increase the injury index, with the aggravation of the external temperature and relative humidity of the air higher in Brazil. We conclude that the external ambience influences the internal ambience and added to the management and reuse of the litter may interfere in increasing injury score as the birds gain more weight. Keywords: cushion plant lesion, contact dermatitis, negative pressure, ambience.

Objective: to evaluate the effectiveness of topical application of negative pressure (VAC-therapy) for frostbites and to improve treatment outcomes in patients with cold injury to the extremities due to a combination with early surgical exposure. Material and methods. The study included 147 patients with cold injury aged 16 to 79 years (mean age 44.0 ± 1.2 years), among whom there were 87 % of men and 13 % of women. Application of VAC-therapy (study group, VAC+) was performed in 29 patients, and 118 subjects underwent treatment without negative pressure (control group, VAC–). Results. Using the VAC-therapy as a component of early surgical treatment of frostbites is an effective measure from the first days after a cold injury and allows to preserve maximally the tissues of the limbs, to reduce the volume of necrectomy and to decrease the number of amputations in deep frostbites, at that, pathogenetic orientation of tissue decompression in the reactive period is determined by the improvement of microcirculation, prevention of thrombosis and secondary infection, necessitates the use of VAC+ in the case of dermoplasty and limits the administration of negative pressure in foot amputation, and prognostic criteria for further treatment measures are baseline parameters of anatomic severity of frostbite of extremities, C-reactive protein and creatine kinase activity in the blood serum. There has been detected a more severe course of the pathological process in the study group, as evidenced by the significantly large changes in 19 initial clinical-laboratory and instrumental indicators out of 31. Patients with VAC+ and VAC– did not differ only in minute volume of the blood, vegetative index and peripheral vascular resistance, indicators of recalcification time, vascular endothelial function, physical and chemical adsorption and rheological parameters of the blood serum. Conclusions. The results of therapeutic interventions using VAC-therapy in cold injury are closely related, Цель работы: оценить эффективность локального применения отрицательного давления (VAC-терапии) при отморожениях и улучшить результаты лечения больных с холодовой травмой конечностей за счет комбинации с ранним хирургическим воздействием. Материал и методы. Под наблюдением находились 147 больных с холодовой травмой в возрасте от 16 до 79 лет (в среднем 44,0 ± 1,2 года), среди которых было 87 % мужчин и 13 % женщин. VAC-терапия (основная группа, VAC+) была применена у 29 больных, a у 118 лечение проводили без отрицательного давления (контрольная группа, VAC–). Результаты. Использование VAC-терапии как составляющей раннего хирургического лечения отморожений является эффективным мероприятием уже с первых суток после холодовой травмы и позволяет максимально сохранить ткани конечности, уменьшить объем некрэктомий и снизить число ампутаций при глубоких отморожениях, причем патогенетическая направленность декомпрессии тканей в реактивном периоде определяется улучшением микроциркуляции, предупреждением тромбообразования и вторичной инфекции, диктует необходимость использования VAC+ в случаях выполнения дермопластики и ограничивает назначение отрицательного давления при ампутациях стоп, а прогностическими критериями в отношении дальнейших лечебных мероприятий являются исходные показатели анатомической тяжести отморожений конечностей, С-реактивного протеина и активности креатинкиназы в сыворотке крови. Установлено более тяжелое течение патологического процесса в основной группе, о чем свидетельствуют достоверно большие изменения 19 исходных клинико-лабораторных и инструментальных показателей из 31. Пациенты с VAC+ и VAC– не различались между собой лишь по минутному объему крови, вегетативному индексу и периферическому сосудистому сопротивлению, показателям времени рекальцификации, эндотелиальной функции сосудов и физико-химическим адсорбционно-реологическим параметрам сыворотки. Выводы. Результаты лечебных мероприятий с использованием VAC-терапии при холодовой травме тесно свя, Мета роботи: оцінити ефективність локального застосування негативного тиску (VAC-терапії) при відмороженнях та поліпшити результати лікування хворих із холодовою травмою кінцівок за рахунок комбінації з раннім хірургічним втручанням. Матеріал і методи. Під наглядом перебувало 147 хворих із холодовою травмою віком від 16 до 79 років (в середньому 44,0 ± 1,2 року), серед яких було 87 % чоловіків і 13 % жінок. Застосування VAC-терапії (основна група, VAC+) було виконано 29 хворим, a 118 лікування проводили без негативного тиску (контрольна група, VAC–). Результати. Використання VAC-терапії як складової раннього хірургічного лікування відморожень є ефективним засобом вже з першої доби після холодової травми і дозволяє максимально зберегти тканини кінцівки, зменшити обсяг некректомій і знизити кількість ампутацій при глибоких відмороженнях, причому патогенетична спрямованість декомпресії тканин в реактивному періоді визначається поліпшенням мікроциркуляції, запобіганням тромбоутворенню і вторинній інфекції, диктує необхідність використання VAC+ у випадках виконання дермопластики й обмежує призначення негативного тиску в разі ампутації ступень, а прогностичним критерієм щодо подальших лікувальних заходів є початкові показники анатомічної тяжкості відмороження кінцівок, С-реактивного протеїну й активності креатинкінази в сироватці крові. Встановлено більш тяжкий перебіг патологічного процесу в основній групі, про що свідчать вірогідні зміни 19 початкових клініко-лабораторних та інструментальних показників з 31. Пацієнти з VAC+ і VAC– не відрізнялися між собою лише за хвилинним об’ємом крові, вегетативним індексом і периферійним судинним опором, показниками часу рекальцифікації, ендотеліальної функції судин й фізико-хімічними параметрами адсорбційно-реологічних властивостей сироватки. Висновки. Результати лікувальних заходів з використанням VAC-терапії при холодовій травмі тісно пов’язані з клініко-лабораторним перебігом патологічного процесу, а виділені прогностичні критер

Intermeshing counter-rotating twin screw extruders (ICRTSE) are used extensively in the polymer processing industry for pelletizing, devolatilization and extrusion of various plastic products. ICRTSE have better positive displacement ability and are more suitable for shear sensitive materials compared to other types of twin screw extruders. The objectives of this thesis are to understand the flow mechanism and the effects of screw geometries and processing conditions in the ICRTSE. First, a simple flow model based on a volume of the conveying element of ICRTSE was used to calculate flow rate. Since ICRTSE do not give complete positive displacement, the various leakage flows were identified and taken into account in the simple flow model. Although the simple flow model provided reasonable results in terms of flow rate, computer simulations were found necessary due to the limitations of simple flow model. Second, a 3D computer simulation of ICRTSE was developed for various screw geometries and processing conditions. Both Newtonian and non-Newtonian fluids were examined. It was shown the simple model based on geometrical parameters for pumping behaviour give reasonable prediction of flow rate. It was found that determination of negative pressure should be taken into account in numerical simulations. The pumping efficiency is influenced positively by the ratio of flight width-to-channel width but it is affected negatively by the screw pitch length. It is negligibly changed with screw speed. Finally, the dominant flow is shear flow in ICRTSE and therefore, dispersive mixing capacity is very limited due to a lack of elongational effects., Master of Applied Science (MASc)

Reynolds equations and one-phase model with N-S (Navier Stocks) equations are widely used to calculate pressure distribution in the liquid film. In most cases, negative pressure exits in the obtained results. In a water-flooded single screw compressor, it is necessary to investigate the pressure of water film along the whole tooth flank. A negative pressure may not be right, because that when the pressure is lower than the saturated vapor pressure, cavitation occurs. In this paper, we investigated the pressure distribution of the water film with cavitation model. Results were compared to the pressure distribution obtained by one-phase model using N-S equations. Results show that difference of pressure distribution obtained by the two models is very similar for the positive pressure distribution. For the negative pressure distribution, the saturated vapor pressure could be applied to replace the results obtained by one-phase model with very small errors. Therefore, one-phase model will be effective to simulate pressure distribution along the tooth flank by using the vapor pressure to replace the negative pressure.

Heat pipes and loop heat pipes have long been recognized as attractive alternatives to conventional heat exchangers, but the limit in the magnitude of the capillary pressures generated by the wicks in conventional designs has placed a severe limit on their applicability in vehicles and other large-scale applications. In this project, we aim to overcome this limitation by designing heat pipes with nano-porous wicks that support 10s of bars of capillary pressure. To this end, we are developing design concepts for heat pipes operating in this new regime, developing new fabrication strategies for hierarchically structured wicks that maximize capillary pressures while maintaining reasonable hydraulic resistances, and elucidating the strategies exploited by vascular plants to manage large capillary pressures and the associate metastability of the liquid phase., The original document contains color images. Prepared in cooperation with Harvard University.

Reynolds equations and one-phase model with N-S (Navier Stocks) equations are widely used to calculate pressure distribution in the liquid film. In most cases, negative pressure exits in the obtained results. In a water-flooded single screw compressor, it is necessary to investigate the pressure of water film along the whole tooth flank. A negative pressure may not be right, because that when the pressure is lower than the saturated vapor pressure, cavitation occurs. In this paper, we investigated the pressure distribution of the water film with cavitation model. Results were compared to the pressure distribution obtained by one-phase model using N-S equations. Results show that difference of pressure distribution obtained by the two models is very similar for the positive pressure distribution. For the negative pressure distribution, the saturated vapor pressure could be applied to replace the results obtained by one-phase model with very small errors. Therefore, one-phase model will be effective to simulate pressure distribution along the tooth flank by using the vapor pressure to replace the negative pressure.

Negative pressure wound therapy (NPWT) has been widely adopted for the treatment of deep sternal wound infections due to its excellent clinical outcome. However, the mechanisms of action and effects on hemodynamics have not been thoroughly elucidated. The aims of the work presented in this thesis were, therefore, to examine the effects of NPWT on sternotomy wounds and on the intrathoracic organs. An uninfected porcine sternotomy wound model was used in all studies. The studies showed that negative pressure is transmitted only to tissues that are in direct contact with the foam dressing and not to deeper parts of the wound or thoracic cavity. As NPWT was applied, a transient increase was seen in the plasma levels of norepinephrine and epinephrine, followed by an increase in the adrenergic co-transmitter neuropeptide Y, which may reflect the effect of NPWT on the intrathoracic organs. Increased levels of the sensory nerve transmitter substance P may result from shearing forces arising from the mechanical effects of the negative pressure. Magnetic resonance imaging showed that cardiac output increased while the cardiac pumping efficiency decreased following sternotomy, and then returned to presternotomy values when the negative pressure resealed the thorax. NPWT contracts the wound and causes macrodeformation of the wound edge tissue. This may contribute to the clinical benefits of NPWT over open-chest treatment, including the stabilizing effect and reduced need for mechanical ventilation. The results of the present work underline the importance of correct placement of the wound filler with regard to pressure transmission. The findings also reduce concerns that NPWT could impair cardiac output, and emphasize the beneficial effects of temporary closure provided by NPWT on restoring the intrathoracic anatomy.