Laminar Circulation Research Articles

The investigation of mass transfer coefficients in a pulsed regular packed column applying SiO2 nanoparticles

Abstract Mass transfer coefficient is one of the major parameters for liquid–liquid extraction phenomenon in a pulsed packed column. A small scale of pulsed regular packed column used in this study. The effect of nanoparticles on mass transfer coefficient was investigated. For this purpose, kerosene saturated with water, water saturated with kerosene and acetic acid were used as the dispersed phase, continuous phase, and solute, respectively. The nanofluids used were prepared by dispersing SiO 2 nanoparticles of 0.01, 0.05 and 0.1 vol% in dispersed phase as base fluid employing ultrasonic technic. The experimental mass transfer coefficient was compared with three basic mass transfer coefficient equations of Newman (for stagnant drops), Kronig–Brink (for laminar circulation inside drops), and Handlos–Baron (for turbulent circulation inside drops). A new correlation is derived for the prediction of effective diffusivity coefficient as a function of Reynolds number. Good agreement was found between prediction values and experimental data.

MRI Verification of a Case of Huge Infantile Rhabdomyoma

Introduction:Cardiac rhabdomyoma is type of benign myocardial tumor that is the most common fetal cardiac tumor. Cardiac rhabdomyomas are usually detected before birth or during the first year of life. They account for over 60% of all primary cardiac tumors.Case report:A 6 month old child with coughing and obstruction in breathing, was hospitalized in the Pediatric Clinic in UCCK, Pristine. The difficulty of breathing was heard and the pathological noise of the heart was noticed from the pediatrician. In the echo of the heart at the posterior and apico-lateral part of the left ventricle a tumoral mass was presented with the dimensions of 56 × 54 mm that forwarded the contractions of the left ventricle, the mass involved also the left ventricle wall and was not vascularized. The right ventricle was deformed and with the shifting of the SIV on the right the contractility was preserved. Aorta, the left arch and AP were normal with laminar circulation. The pericard was presented free. Radiography of thoracic organs was made; it resulted on cardiomegaly and significant bronchovascular drawing. It was completed with an MRI and it resulted on: Cardiomegaly due to large tumoral mass lesion (60×34 mm) involving lateral wall of left ventricle. It was isointense to the muscle on T1W images, markedly hyperintense on T2W images. There were a few septa or bant like hypointensities within lesion. On postcontrast study it showed avid enhancement. The left ventricle volume was decreased. Mild pericardial effusion was also noted. Surgical intervention was performed and it resulted on the histopathological aspect as a huge infantile rhadbomyoma.Conclusion:In most cases no treatment is required and these lesions regress spontaneously. Patients with left ventricular outflow tract obstruction or refractory arrhythmias respond well to surgical excision. Rhabdomyomas are frequently diagnosed by means of fetal echocardiography during the prenatal period.

The Ecological Restoration of the Tarquinia Salterns drives the temporal changes in the benthic community structure

1 - Although wetland ecosystems are able to sustain high degree of biological diversity and provide social and economic value, they are also the most impacted and degraded of all ecological systems. 2 - Natural and human-based alterations are particularly evident in small aquatic ecosystems, where the recovery time can be greatly reduced because of the geological and geomorphological characteristics of the sites. 3 - Although seldom used in lentic environment, benthic communities may represent a suitable tool to measure the recovery effects in aquatic ecosystems, due to several characteristics that make them useful as bioindicator. 4 - Here we study the response of benthic communities to the recovery of the Tarquinia Salterns after their abandon and consequent habitat degradation. The increased deposition of organic and inorganic sediments entailed shallow ponds and laminar circulation, causing eutrophication. The ecological restoration of the site allowed reinstating the water depth and flow and returned environmental parameters (mainly dissolved oxygen) to their typical values. 5 - We measured several characteristics of species assemblage in three different sites of the Tarquinia Salterns, covering a period of ten years spanning from pre-recovery to post-recovery phases. 6 - Our results are twofold: i) they show the feasibility of monitoring wetland restoration activities by investigating the pattern of species assemblage in benthic ecological communities and, ii) show the importance of regional and local processes in the composition and response of benthic communities to perturbations.

Numerical modeling of laminar circulation flow in a square cavity with a moving boundary at high Reynolds numbers

Laminar circulation flow in a square cavity is numerically analyzed at high Reynolds numbers (of up to 40,000).

Numerical Modeling of Laminar Circulation Flow in a Cubic Cavity with a Moving Face

Laminar circulation flow in a cubic cavity with a moving face is numerically analyzed. The jet‐vortex elements of the flow which develop in the cavity are identified.

Vascular perfusion in horses with chronic laminitis.

Vascular perfusion casts were used to define and characterise the macroscopic perfusion defects present in the distal digit of 11 horses affected by chronic laminitis. Five clinically normal horses were used as controls. Based on clinical history and clinical status, horses with chronic laminitis were classified as being potentially treatable or clinically refractory. Eleven macroscopic vascular defects were noted in the casts from horses with laminitis. Four types of lesions were identified in the submural laminar circulation, 3 in the coronary bed and 4 were associated with the solar circulation. Multiple defects were present and a definite trend was noted for the perfusion defects to be worse in the casts of clinically refractory subjects than in those considered treatable. This information suggests that evaluation of circulatory status should add significantly to the ability to separate treatable from clinically refractory patients. Results also indicated that ventral displacement of the third phalanx (sinkers) and compression of the solar vasculature are more prevalent than is presently thought.

A scanning electron microscopical study of the dermal microcirculation of the equine foot

The microcirculation of the dermal laminae and papillae of the equine foot from seven clinically normal Australian ponies was studied using an improved microvascular casting corrosion technique and scanning electron microscopy. Casts of veins, arteries, capillaries and arteriovenous anastomoses (AVAs) were readily identified by their characteristic surface morphology. Arteries entered the laminar circulation axially, between pairs of axial veins, and were connected to each other by smaller calibre interconnecting arteries. Short abaxial branches of the axial interconnecting arteries gave rise to tufts of predominantly, proximodistally orientated, capillaries arranged abaxially in rows. The laminar veins anastomosed with each other extensively (the axial venous plexus) and formed most of the vascular skeleton of casts of the dermal laminae. AVAs were found throughout the laminar circulation but the largest and longest (40 mu diameter) were found clustered close to the origin of the axial arteries. The density of the laminar AVAs was estimated to be 500 AVAs/cm2. Blood vessels of the dermal papillae of the periople, coronary band, distal laminae, sole and frog shared a basic structural organisation. The cast of each papillary unit consisted of a central artery and vein enmeshed in a sheath of fine capillaries. At intervals along the length of the central artery were short branches which gave rise to tufts of capillaries. The capillaries formed a tortuous anastomosing plexus which encircled the papillary unit and drained into the central vein at intervals along its length. AVAs were always present at the base of the papillary units and anastomoses connected the central artery and vein. AVAs are important components of the dermal microcirculation of the equine foot and their distribution and density is compatible with their proposed role in the pathophysiology of equine laminitis.