Conductive Vessel Research Articles

Magnetically- regulated close contact melting for high-power-density latent heat energy storage

Rapid melting of solid-liquid phase change materials (PCMs) is critical to the high-power-density latent heat energy storage and efficient thermal management. The pressure-enhanced close contact melting is seen as a promising method because of the suppressed heat transfer resistance between the heating surface and the melt front during thermal charging, but it remains a key challenge how to tactfully apply external pressure for a practical device. Herein, we present a magnetically-regulated close contact melting strategy for rapid melting of PCMs from the perspective of the practical application. In this method, a PCM and a permanent magnet are contained inside a highly thermally conductive vessel, and the magnet regulated by another one can push the solid PCM toward the heating surface. Consequently, the superheated molten PCM can be instantly removed from the heating surface due to the magnetic force so as to achieve the suppressed thermal resistance. The temperature-control performance of paraffin wax is evaluated under various applied external forces and heat loads. Experimental results indicate that the heating surface temperature can be controlled near the melting temperature of PCM even under a relatively high heating flux. With applying the external pressure of 900 Pa, the average heat transfer resistance is reduced to lower than 4.5 × 10−4 K·m2·W−1. Finally, a closed thermal management device is fabricated and measured by using a graphite vessel to encapsulate the magnet and the PCMs such as paraffin and low-melting-point alloy. This device demonstrates good recyclability for repeated thermal charging/discharging. Our work provides a new method to develop the practical thermal management device based on pressure-enhanced close contact melting.

A New Phantom that Simulates Electrically a Human Blood Vessel Surrounded by Tissues: Development and Validation Against In-Vivo Measurements.

This study aims to develop a phantom that simulates the electrical properties of a human blood vessel surrounded by tissues, inside which bubbles can be infused to mimic Decompression Sickness (DCS) conditions. This phantom may be used to calibrate novel electrical methods for bubbles detection in humans and study bubble dynamics during DCS. It may contribute to the limitation of in-vivo trials and time/effort saving, while its use can be extended to other biomedical applications. To facilitate the design of the phantom, we perform first in-vitro measurements in a flow-loop and in-vivo measurements in a swine, in order to detect infused bubbles of a few tenths μm-representing Decompression Sickness conditions-in the test liquid flow and blood flow, respectively, by means of "I-VED" EU patented electrical impedance spectroscopy technique. Results show that the proposed phantom, consisting of a spongy specimen soaked in agar gel in the presence of electrolyte with a hole along it, simulates adequately the electrical properties of a human blood vessel surrounded by tissues. I-VED demonstrates pretty high sensitivity to sense micro-bubbles over the partially conductive vessel walls of the phantom or the isolated animal vein, as well as in the flow-loop: bubbles presence increases electrical impedance and causes intense signal fluctuations around its mean value.

Measurement of electric fields of charged spray clouds of conductive liquids in free space and in a conductive vessel

The process of spraying liquids generated electrical charges. The question therefore arises as to whether this electrostatic charge represent an ignition hazard when an explosive mixture is present. This hazard occurs when cleaning vessels, in which an explosive mixture is formed by residues of easily flammable liquids or the cleaning medium itself. Although measurement techniques and methods exist for detecting this electrostatic charging process, they have not been sufficiently scientifically proven. The Chilworth JCI 131 adverse conditions field meter is to be used to measure the electrostatic charging of sprayed liquids. It shall be validated by measuring the electric field strength of a flat spray water jet in low-pressure range (8 bar) charged by contact charging and accumulation of free electrons of a commercial, insulated arranged electrostatic spraying system (up to - 90 kV). A flat-jet nozzle is selected which atomizes the spray jet, which serves as the measuring surface, sufficiently large. This arrangement is further investigated in a 1 m3 stainless steel IBC. The investigations presented are part of a project aiming to extend the scope of the German Technical Rules for Hazardous Substances (TRGS) of TRGS 727, which regulate avoiding ignition hazards resulting from electrostatic charging. The aim is to reach an understanding that allows provisions for safe cleaning of “small” and “medium-sized” containers up to 50 m3. This project is funded by DGUV (German Social Accident Insurance) and partners from the industry.

Identifying which conduits are moving water in woody plants: a new HRCT-based method.

In vivo imaging methods are useful for examination of plant vascular tissues, particularly in the identification of fluid vs gas-filled conduits; however, these methods may not allow for the simple identification of conductive conduits. Our aim in the present study was to develop a method that would allow for the in vivo identification of conductive conduits. Intact plants and segments of grapevine (Vitis vinifera L.) and intact American chestnut (Castanea dentata (Marshall) Borkh.) saplings were examined. We found that iohexol, a water soluble iodine-rich molecule, was a useful contrast agent. We also stained the xylem of segments and gas- dried samples to compare between intact scans and excised segments. Iohexol could be readily fed through cut roots or stems into the transpiration stream, was successfully transported through the xylem and marked conductive vessels within high-resolution computed tomography (HRCT) scans. Iohexol results were comparable to those obtained by staining cut segments, with iohexol detecting greater numbers of smaller conduits in some samples. Samples contained gas-filled conduits, as well as both conductive (containing iohexol tracer) and non-conductive (no iohexol tracer) fluid-filled vessels. Fluid-filled non-conductive vessels were likely still developing or were not connected to the sap stream by a low resistance pathway. We found minimal differences between intact and excised segments other than excision-related dilution of iohexol. Both vessels and vasicentric tracheids were filled with iohexol in chestnut, providing a new tool to study the functions of these different cell types. The use of iohexol as a tracer to identify conductive vessels may greatly improve the utility of HRCT as a tool in the study of plant hydraulic function. Future studies using HRCT will likely need to incorporate conductive vessel markers or controls into experiments due to the presence of non-conductive fluid-filled vessels within the xylem.

A Pulsed Magnet System for a Possible Future Field Reversed Configuration Experiment

From a magnet engineering perspective, the field-reversed configuration (FRC) fusion concept is commercially attractive due to its cylindrical configuration. Essentially, all large coils are solenoidal, which enables efficient structural support and relative ease of manufacturing, thereby enhancing commercial viability. A design option for future experimental FRC devices, which is currently under study, would require a large number of normal conducting electromagnets to produce the required magnetic field configuration for approximately 30 ms. One of the major challenges with such a system is a requirement to achieve a magnetic field profile which evolves with time and in which both eddy currents in major components and large plasma currents are also important magnetic field contributors. This paper describes contemplated magnetic configurations and the main types of coils and the coil design choices for each. It also discusses transient analysis performed to predict fields internal to a conductive vessel, while ramping magnetic fields, and accounting for vessel eddy current and plasma contributions. An estimate of harmonic errors due to displacement of the coils is provided. The dominant error field component is found to be from the dipole contribution. Harmonic errors from eddy currents due to plasma are briefly discussed.

The relationship between intravascular ultrasound-derived percent total atheroma volume and fractional flow reserve in the intermediate stenosis of proximal or middle left anterior descending coronary artery

BackgroundIt remains undefined whether the atherosclerotic disease extent of the conductive vessel (expressed as intravascular ultrasound [IVUS]-derived percent total atheroma volume [%TAV]), correlates with functional severity of intermediate stenosis of left anterior descending artery (LAD). MethodsAn IVUS study and fractional flow reserve (FFR) measurements performed in 130 patients with coronary angiographic intermediate stenosis of proximal or middle LAD. %TAV was calculated as the percentage of total vessel volume occupied by total atheroma volume on IVUS. ResultsA significant correlation was observed between %TAV and FFR (r=−0.71, p<0.001). Minimal lumen area (MLA) correlated moderately with FFR (r=0.54, p<0.001). The independent predictors of FFR<0.8 were %TAV (odds ratio [OR]: 1.29, 95% confidence interval [CI]=1.18–1.40, p<0.001) and MLA (OR: 0.37, 95% CI=0.16–0.85, p=0.019). A receiver-operating characteristic curve suggested %TAV≥39.0% (sensitivity 85%, specificity 83% and area under curve [AUC]=0.90) and MLA≤2.6mm2 (sensitivity 72%, specificity 70% and AUC=0.75) as the best cut-off values for FFR<0.8. Forty-eight point five (48.5%) of total studied lesions (63/130) showed %TAV≥39.0%. Eighty-four point four (84.4%) of lesions (38/45) with %TAV≥39.0% and MLA≤2.6mm2, and 72.2% of lesions (13/18) with %TAV≥39.0% and MLA>2.6mm2, FFR was less than 0.8. ConclusionsVolumetric quantification of the atherosclerotic disease extent of the coronary artery, expressed as IVUS-derived %TAV, showed a strong correlation with FFR. Not only the segmental luminal narrowing but also the total plaque burden of conductive artery are major determinants for the presence of myocardial ischemia in intermediate stenosis of LAD.

Effect of the vacuum vessel on the measurements of mirnov oscillation in TCABR

Magnetic field due to instabilities in plasma is expected to be reflected in the conductive vessel wall. We evaluate the reflection effect in the Brazilian tokamak TCABR. The magnetic field due to the plasma is represented by a toroidal harmonic function in vacuum and the reflected field is written as a series of harmonic functions in vacuum, generated in the external region. The conclusion is that a signal originated in the plasma may be strongly deformed, close to the wall. Even far from the wall, around the plasma, the effect of the wall may still be considerable.

Fosinopril improves regulation of vascular tone in mesenteric bed of diabetic rats.

Because diabetes mellitus leads to vascular dysfunction, we examined the microvascular endothelial and smooth muscle function in long-term diabetes and a possible influence of fosinopril treatment (10 mg/kg). We investigated isolated perfused mesenteric beds of diabetic rats (4 groups: control, control + fosinopril, diabetes, diabetes + fosinopril; diabetes of 6-month duration, induced by streptozotocin, STC) were investigated using computer-assisted microvideoangiometry. Vascular diameter of four different vascular regions [classified as conductive (G1, 303 +/- 6.5 mu m and G2, 239 +/- 6.3 mu m) and resistance (G3, 192 +/- 4.5 mu m and G4, 124 +/- 2.6 mu m) vessel generations; resting conditions, control group] were increased in diabetes by approximately 20%. However, the endothelium-dependent relaxation in response to 1 mu M acetylcholine (ACh) was reduced from 38-44% to 20-25% (diabetes mellitus) with maximal impairment in G4 vessels. This could be significantly antagonized by fosinopril treatment. Similarly, vasodilation in response to 1 mu M glyceroltrinitrate (GTN) was reduced from 50-58 to 20-30%, but was partially prevented by fosinopril (32-38%), whereas potassium chloride (KCl)-induced vasoconstriction did not show differences between the groups. Inhibition of nitric oxide (NO) synthesis by 3 mu M L-NG-nitro arginine (L-NNA) resulted in a slight vasoconstriction of all vessels (12-25%), with maximum response in G3/G4. This was not altered by disease or treatment. We conclude that (a) long-term diabetes leads to endothelial and smooth muscle dysfunction with reduced capability of vasodilation and either an impairment of NO release or a reduced smooth muscle responsiveness to and (b) a predominant impairment of NO-dependent regulation in small resistance vessels, and (c) that fosinopril treatment can at least partially prevent this vascular dysfunction.

Changes of specific conductivity of blood serum in vivo after x-irradiation.

DURING the investigation of biological changes in the serum of irradiated animals the specific conductivity of rabbit serum after X-irradiation was followed. Twenty animals (Viennese White) were used for the experiment. They were divided into four groups of five animals each. The irradiation was carried out with doses of 250, 500, 1,000 and 1,500 r., using a ‘Macrophos 250’ apparatus. The conditions of irradiation were as follows: E, 215 kV; I, 15 m.amp; flow of doses, 8 r./min; half-layer, 1.6 mm Cu. 2.5 ml. of blood were taken from the ear vein 30 min before irradiation (control data) and 4 h post-irradiation. The blood serum was obtained by centrifuging the blood at 3,000 r.p.m. for 15 min. The serum resistance was measured with a ‘Konduktoskop III’ apparatus, its Wheat-stone bridge supplied by stream flow of 5,000 c/s. Serum was heated to 20° ± 0.05° C and measured in the conductive vessel with platinum electrodes coated with platinum-black. The resistance capacity of the conductivity-vessel, C = 235.73 cm−1.