Creating lifting force in liquids via thermal gradients.

In this paper, we explore a concept and present the first experimental evidence to show that it is possible to form a stable liquid film and create lifting force at the interface via thermal gradient to minimize interfacial rubbing of surfaces and the associated wear. The approach is based on manipulating the flow behavior via thermocapillary, which describes how a liquid can be made to flow from warm to cold regions purely by inducing a thermal gradient. We show that liquid bridges between two parallel plates can be manipulated and stabilized under a combined effect of the thermocapillary flow and the Couette flow, which describes the motion of a viscous fluid between two parallel plates in a relative sliding motion. The equilibrium stage is confirmed under different experimental conditions of a thermal gradient, interfacial gap, liquid viscosity, and liquid bridge volume. A strategy is proposed to control liquid motion and create lifting force between two plates. A theoretical model is also presented to illustrate the principle of the equilibrium stage. Creating lifting forces at the interface offers a new thermo-hydrodynamic tool for manipulating liquids behavior. This approach has the potential for controlling liquid motion in mechanical components and nature.

A Unified Treatment of Tribo-Components Degradation Using Thermodynamics Framework: A Review on Adhesive Wear.

An extensive survey of open literature reveals the need for a unifying approach for characterizing the degradation of tribo-pairs. This paper focuses on recent efforts made towards developing unified relationships for adhesive-type wear under unlubricated conditions through a thermodynamic framework. It is shown that this framework can properly characterize many complex scenarios, such as degradation problems involving unidirectional, bidirectional (oscillatory and reciprocating motions), transient operating conditions (e.g., during the running-in period), and variable loading/speed sequencing.

Ringlike Migration of a Droplet Propelled by an Omnidirectional Thermal Gradient.

The interfacial phenomenon associated with the ringlike motion of a liquid droplet subjected to an omnidirectional thermal gradient is investigated. An experimentally verified model is proposed for estimating the droplet migration velocity. It is shown that the unbalanced interfacial tension acting on the liquid in the radial direction provides the necessary propulsion for the migration, whereas the internal force acting on the adjoining liquid contributes to the equilibrium condition in the circumferential direction. This study puts forward the understanding of the interfacial spreading phenomenon, the knowledge of which is important in applications where liquid lubricants are encountered with directionally unstable thermal gradients.

Worth a second look: outcomes of patients with initial finding of regular renal tissue in CT-guided renal tumor biopsies.

INTRODUCTION AND OBJECTIVE: Renal tumor biopsy is recommended for histological diagnosis of radiologically indeterminate renal masses, to select patients with small-renal masses for surveillance approaches, before ablative treatments and to confirm metastatic spread of renal cell cancer (RCC), according to the EAU guidelines. We aimed to determine outcomes of patients with suspicious renal masses with initial finding of regular renal tissue in renal tumor biopsies. METHODS: Retrospective database analysis of 101 patients undergoing CT-guided-, percutaneous renal tumor biopsies in local anesthesia. RESULTS: In 23/101 patients, histopathologic evaluation of the biopsies showed regular renal tissue. Of these, two patients underwent simultaneous radiofrequency ablation (RFA), 2/23 underwent radical nephrectomy, despite negative biopsy because of radiological suspicious aspect. Overall, 12 patients underwent a second set of biopsies due to persistent clinical suspicion. Of these, five were diagnosed with RCC: three clear cell renal cell carcinoma (ccRCC) and two papillary renal cell carcinoma (pRCC). Benign tumours were found in two patients. A lymphoma was found in two patients. In 3/12 patients, also the second set of biopsies showed regular renal tissue. CONCLUSION: An unsuspicious histology in CT-guided renal tumor biopsy does not preclude patients with suspicious renal masses from being diagnosed with malignancies.

Discriminatory Ability of Visceral Adiposity Index (VAI) in Diagnosis of Metabolic Syndrome: A Population Based Study.

Background Visceral adiposity index (VAI) has been suggested as an index of visceral adiposity. This study was conducted to determine the discriminatory ability of VAI in diagnosis of metabolic syndrome (MetS). Methods and materials We used the data of 5 312 subjects aged 18-74 years of a cohort study conducted among 6 140 individuals aged 10-90 years in Amol, northern Iran. The city population was divided into 16 strata based on gender and age groups in 10-year intervals. The subjects were randomly selected from each stratum. MetS was defined based on National Cholesterol Education Program Adult Treatment Panel III (NCEP/ATPIII), American Heart Association/National Heart, Lung and Blood Institute (AHA/NHLBI) update of Adult Treatment Panel III (ATPIII), International Diabetes Federation (IDF) and joint interim statement (JIS) definitions. The discriminatory ability of VAI and other obesity measures were evaluated using receiver operating characteristic (ROC) curves. Results While waist circumference (WC) showed the highest discriminatory ability for MetS in IDF definition in men (AUC=0.899 [CI=0.888-0.910]), VAI had the greatest discriminatory ability according to other definitions in men and women. The related AUCs of VAI were 0.866 (95%CI: 0.850-0.881), 0.829 (95%CI: 0.813-0.846), 0.859 (95%CI: 0.844-0.873) and 0.876 (95%CI: 0.863-0.889) based on NCEP/ATPIII, AHA/NHLBI update of ATPIII, IDF and JIS definition in men, and also 0.888 (95%CI: 0.875-0.902), 0.894 (95%CI: 0.881-0.907), 0.883 (95%CI: 0.869-0.897) and 0.879 (95%CI: 0.864-0.894) in women, respectively. Conclusion VAI showed an excellent discriminatory ability in diagnosis of MetS. Considering its relatively simple calculation, this index could be suggested as a reliable tool in medical practice.

On the migration of a droplet on an incline.

A liquid droplet placed on a nonuniformly heated solid surface will migrate from a high temperature region to a low temperature region. The present study reports the results of an experimental investigation on the migration behavior of mineral oil droplets subjected to a thermal gradient on an inclined plane. A particular attention is paid to the relationship between the critical inclination angle and thermal gradients. It is shown that there exists a critical inclination angle at which the droplet migration is halted. This critical inclination angle can be readily predicted using analytical expressions derived in this paper. This study puts forward the understanding of the interface phenomenon of thermocapillary migration on an incline. The knowledge of the critical inclination is important in applications where the migration on an incline must be obstructed to retain adequate lubrication in the desired location.

Thermocapillary Migration of Liquid Droplets Induced by a Unidirectional Thermal Gradient.

A liquid droplet placed on a nonuniformly heated solid surface will migrate from a high-temperature region to a low-temperature region. This study reports the development of a theoretical model and experimental investigation on the migration behavior of paraffin oil droplets induced by the unidirectional thermal gradient. Thin-film lubrication theory is employed to determine the migration velocity of droplets, and temperature dependence of viscosity is taken into account. Comparisons between experimental and numerical results are presented. An effective approach for estimating the thermocapillary migration velocity of droplets on lubrication is proposed.

Pineapple juice as a negative oral contrast agent in magnetic resonance cholangiopancreatography: a preliminary evaluation.

The quality of magnetic resonance cholangiopancreatography (MRCP) images is frequently degraded by high signal from the gastrointestinal tract. The aim of this study is to evaluate pineapple juice (PJ) as an oral negative contrast agent in MRCP. Preliminary in vitro evaluation demonstrated that PJ shortened T(2) relaxation time and hence decreased T(2) signal intensity on a standard MRCP sequence to a similar degree to a commercially available negative contrast agent (ferumoxsil). Electrothermal atomic absorption spectrometry assay demonstrated a high manganese concentration in PJ of 2.76 mg dl(-1), which is likely to be responsible for its T(2) imaging properties. MRCP was subsequently performed in 10 healthy volunteers, before and at 15 min and 30 min following ingestion of 400 ml of PJ. Images were assessed blindly by two Consultant Radiologists using a standard grading technique based on contrast effect (degree of suppression of bowel signal), and image effect (diagnostic quality). There were statistically significant improvements in contrast and image effect between pre and post PJ images. There was particularly significant improvement in visualization of the pancreatic duct, but no significant difference between 15 min and 30 min post PJ images. Visualization of the ampulla, common bile duct, common hepatic and central intrahepatic ducts were also significantly improved at 15 min following PJ. Our results demonstrate that PJ, may be used as an alternative to commercially available negative oral contrast agent in MRCP.

Impact of posterior occlusal support on the condylar position.

The purpose of this study was to investigate condylar displacement related to the loss of posterior occlusal support. Each of 23 subjects received one occlusal adjusted splint that covered all teeth from the right to the left second mandibular molar. None of the subjects had a third molar and none of them had a missing tooth or showed tooth mobility. The splint was inserted and vertical and horizontal condylar position was measured by an ultrasonic motion analyser. The splint was then unilateraly shortened tooth-by-tooth up to the canine tooth and the measurement was repeated after each shortening. Cutting off the splint's second molar on one side lead to a slight ipsilateral cranial motion of the condyle if subjects clenched with maximum voluntary force. If the second and first molar were cut off, a noticeable cranial condylar movement of about 0.3 mm was observed even when teeth occluded with low force. These results suggest that loss of posterior occlusal support as it happens in routine oral rehabilitation leads to a noticeable cranial condyle movement during registration, even if the clenching force is low.