The Constrained Vapor Bubble Experiment - Interfacial Flow Region

Internal heat transfer coefficient of the CVB correlated to the presence of the interfacial flow region. Competition between capillary and Marangoni flow caused Flooding and not a Dry-out region. Interfacial flow region growth is arrested at higher power inputs. 1D heat model confirms the presence of interfacial flow region. 1D heat model confirms the arresting phenomena of interfacial flow region Visual observations are essential to understanding

CVB: the Constrained Vapor Bubble Capillary Experiment on the International Space Station MARANGONI FLOW REGION

The Constrained Vapor Bubble (CVB) is a wickless, grooved heat pipe and we report on a full- scale fluids experiment flown on the International Space Station (ISS). The CVB system consists of a relatively simple setup a quartz cuvette with sharp corners partially filled with either pentane or an ideal mixture of pentane and isohexane as the working fluids. Along with temperature and pressure measurements, the two-dimensional thickness profile of the menisci formed at the corners of the quartz cuvette was determined using the Light Microscopy Module (LMM). Even with the large, millimeter dimensions of the CVB, interfacial forces dominate in these exceedingly small Bond Number systems. The experiments were carried out at various power inputs. Although conceptually simple, the transport processes were found to be very complex with many different regions. At the heated end of the CVB, due to a high temperature gradient, we observed Marangoni flow at some power inputs. This region from the heated end to the central drop region is defined as a Marangoni dominated region. We present a simple analysis based on interfacial phenomena using only measurements from the ISS experiments that lead to a predictive equation for the thickness of the film near the heated end of the CVB. The average pressure gradient for flow in the film is assumed due to the measured capillary pressure at the two ends of the liquid film and that the pressure stress gradient due to cohesion self adjusts to a constant value over a distance L. The boundary conditions are the no slip condition at the wall interface and an interfacial shear stress at the liquid- vapor interface due to the Marangoni stress, which is due to the high temperature gradient. Although the heated end is extremely complex, since it includes three- dimensional variations in radiation, conduction, evaporation, condensation, fluid flow and interfacial forces, we find that using the above simplifying assumptions, a simple successful model can be developed

CVB: The Constrained Vapor Bubble 40 mm Capillary Experiment on the ISS

Discuss the Constrained Vapor Bubble (CVB) 40mm Fin experiment on the ISS and how it aims to achieve a better understanding of the physics of evaporation and condensation and how they affect cooling processes in microgravity using a remotely controlled microscope and a small cooling devic

Evaluation of lumbar spine using MRI in patients with chronic low back pain

Aim: We compared the prevalence of MR imaging features of lumbar spine degeneration in adults and with self-reported low back pain. Evaluating the patient based on the degree of disc bulge correlating findings on MRI study aimed in establishing the role of MRI in prompt diagnosis to assess the degree of disc herniation. Material and Methods : Patients were evaluated each  for the following outcomes : degree of disc bulge, disc degeneration, disc extrusion, disc protrusion, annular fissures, Modic changes, central canal stenosis, spondylolisthesis and spondylolysis, RESULTS : 52 self reported cases of low back pain. 40 of them (80%) met the inclusion criteria, 12 patients had a normal MRI, disc bulge (50%), spondylolysis (20%), disc extrusion (5%), MODIC 1 changes (10%), disc protrusion (5%) and disc degeneration (10%) the degree of disc bulge in the upper lumbar levels showed significant radicular symptoms in symptomatic low back pain patients associated with degenerative changes more in older population with a greater pain scale

Anesthesia management for a case of laryngeal keel placement

Congenital laryngeal web is a rare anomaly with incidence of 1 in 10,000 births. Its clinical presentation may range from an asymptomatic patient or mild hoarseness of voice to severe respiratory stridor. The primary goals of surgical intervention for congenital laryngeal web are to establish a patent airway and to achieve a good voice quality. As recurrence rate after plain excision of laryngeal web is very high, its removal may be coupled by placement of a silastic keel in between vocal cords. Endolaryngeal placement of a keel is definitely less invasive than laryngofissure, but little is known about its anesthesia management. Frequent ventilatory adjustment and endotracheal tube (ETT) manipulations are needed along with vigilant monitoring. Risk of perforation or accidental dislodgment of the ETT and laryngeal edema are other concerns in management. We report a case

Role of ultrasound in evaluation of nodular thyroid lesions

BACKGROUND AND PURPOSE: Thyroid disorders have become widely prevalent in India. Using latest sonography techniques,  evaluation of thyroid nodule and diagnosing as malignant  without FNAC has risen to 90% specificity. MATERIAL AND METHODS: The study was done in  100 patients who came to sonography department with clinical suspicion of thyroid nodule. High frequency superficial ultrasound probe is used in this study. The ultrasound characteristics used in our  examination were echogenicity (hypoechoic /isoechoic /hyperechoic) , composition (solid /cystic /mixed /spongiform), margin, shape, echogenic foci as specified by ACR-TIRADS . RESULTS: In this study on 100 patients with thyroid nodules, 34 cases were classified as TIRADS 3, 4 or 5.  From this 30 patients underwent surgical resection of which 30  people had histopathological proved thyroid carcinoma meaning the accuracy of sonography with TIRADS has 90% specificity and 100% sensitivity in diagnosing malignancy.  CONCLUSION: Ultrasonography with ACR TIRADS  scoring is very much helpful tool  in diagnosing malignancy without FNAC is cost effective and easy available modality. In hands of a good sonologis

Correlation of findings of CT and MRI in skull lesions

Introduction: Skull vault lesions are often asymptomatic and are usually discovered incidentally during computed tomography or magnetic resonance imaging of the brain. Calvarial lesions can be benign or malignant. Calvarial lesions may arise from skull bones or can be secondary to invasion of skull vault from brain or scalp based lesions. Objectives: The aim of this study is to study the role of CT and MRI in evaluating skull vault lesions. Material and methods: 50 patients with skull vault lesions were considered in our study.The patients underwent CT and MRI scans of head. Results: Among 50 patients, most common skull vault lesions were Skull metastases, osteoma and epidermoid cyst. Chordoma, osseous hemangioma and intraosseous meningioma were the least encountered lesions. Conclusion: This article has demonstrated that CT and MRI have complementary roles in determining the nature of skull lesions. CT is the most accurate method for evaluating bone destruction of the inner and outer tables while MRI is best to assess marrow involvement, soft tissue component and invasion of adjacent tissues

Effect of Capillary and Marangoni Forces on Transport Phenomena in Microgravity

The Constrained Vapor Bubble (CVB) experiment concerns a transparent, simple, “wickless” heat pipe operated in the microgravity environment of the International Space Station (ISS). In a microgravity environment, the relative effect of Marangoni flow is amplified because of highly reduced buoyancy driven flows as demonstrated herein. In this work, experimental results obtained using a transparent 30 mm long CVB module, 3 mm × 3 mm in square cross-section, with power inputs of up to 3.125 W are presented and discussed. Due to the extremely low Bond number and the dielectric materials of construction, the CVB system was ideally suited to determining if dry-out as a result of Marangoni forces might contribute to limiting heat pipe performance and exactly how that limitation occurs. Using a combination of visual observations and thermal measurements, we find a more complicated phenomenon in which opposing Marangoni and capillary forces lead to flooding of the device. A simple one-dimensional, thermal-fluid flow model describes the essence of the relative importance of the two stresses. Moreover, even though the heater end of the device is flooded and the liquid is highly superheated, boiling does not occur due to high evaporation rates

Role of Ultrasound in Evaluation of Nodular Thyroid Lesions

BACKGROUND AND PURPOSE: Thyroid disorders have become widely prevalent in India. Using latest sonography techniques,  evaluation of thyroid nodule and diagnosing as Malignant  without FNAC has risen to 90% specificity. MATERIAL AND METHODS: The study was done in  100 patients who came to sonography department with clinical suspicion of thyroid nodule. High frequency superficial ultrasound probe is used in this study. The ultrasound characteristics used in our  examination were echogenicity (hypoechoic /isoechoic /hyperechoic) , composition (solid /cystic /mixed /spongiform), margin, shape, echogenic foci as specified by ACR-TIRADS . RESULTS: In this study on 100 patients with thyroid nodules, 34 cases were classified as TIRADS 3, 4 or 5.  From this 30 patients underwent surgical resection of which 30  people had histopathological proved thyroid carcinoma meaning the accuracy of sonography with TIRADS has 90% specificity and 100% sensitivity in diagnosing Malignancy.  CONCLUSION: Ultrasonography with ACR TIRADS  scoring is very much helpful tool  in diagnosing Malignancy without FNAC is cost effective and easy available modality. In hands of a good sonologis