Measuring the depth of surface cracks using alternating current potential drop technique, with suppression of the influence of the electromagnetic properties of the metal

Traditional measuring techniques often lead to errors due to the need to register signals in both defective and defect-free areas. In this paper, we introduce an alternating current potential drop technique with detuning from the influence of variations in the electromagnetic properties of the metal achieved by registering a signal only at the defective site. We show that, with an appropriate choice of measurement parameters, the use of the proposed technique leads to an increase in sensitivity to the crack depth as well as to an increase in the measurement range.

The Oscillatory Spinning Drop Technique. An Innovative Method to Measure Dilational Interfacial Rheological Properties of Crude Oil-Brine Systems in the Presence of Asphaltenes

The oscillatory spinning drop method has been proven recently to be an accurate technique to measure dilational interfacial rheological properties. It is the only available equipment for measuring dilational moduli in low interfacial tension systems, as it is the case in applications dealing with surfactant-oil-water three-phase behavior like enhanced oil recovery, crude oil dehydration, or extreme microemulsion solubilization. Different systems can be studied, bubble-in-liquid, oil-in-water, microemulsion-in-water, oil-in-microemulsion, and systems with the presence of complex natural surfactants like asphaltene aggregates or particles. The technique allows studying the characteristics and properties of water/oil interfaces, particularly when the oil contains asphaltenes and when surfactants are present. In this work, we present a review of the measurements of crude oil-brine interfaces with the oscillating spinning drop technique. The review is divided into four sections. First, an introduction on the oscillating spinning drop technique, fundamental and applied concepts are presented. The three sections that follow are divided according to the complexity of the systems measured with the oscillating spinning drop, starting with simple surfactant-oil-water systems. Then the complexity increases, presenting interfacial rheology properties of crude oil-brine systems, and finally, more complex surfactant-crude oil-brine systems are reviewed. We have found that using the oscillating spinning drop method to measure interfacial rheology properties can help make precise measurements in a reasonable amount of time. This is of significance when systems with long equilibration times, e.g., asphaltene or high molecular weight surfactant-containing systems are measured, or with systems formulated with a demulsifier which is generally associated with low interfacial tension.

Investigation of Two Immiscible Liquids Wetting at Elevated Temperature: Interaction Between Liquid FeMn Alloy and Liquid Slag

The goal of the current work is to develop a methodology to study the wetting behaviour of two immiscible liquids at high temperatures, and to investigate the parameters which influence the wetting properties. The wetting behaviour between synthetic FeMn alloy and synthetic slag has been investigated using the sessile drop technique. Two experimental procedures were implemented under both Ar and CO atmospheres: (a) FeMn alloy and slag placed next to each other on a graphite substrate; and (b) one droplet dropped on top of the other. FactSage is applied to calculate reactions and their equilibrium. The current work presents and demonstrates the suggested methodologies. The results indicate that the wetting between slag and FeMn alloy is relatively stable at temperatures up to 100 K above their melting points, regardless of the droplet size and atmosphere. MnO reduction is accelerated at higher temperature, especially in CO, thus increasing the wetting between FeMn alloy and slag, eventually fusing together. At even higher temperature, slag separates from FeMn alloy due to changing chemical composition during non-equilibrium MnO reduction.

First Approach to Measure Interfacial Rheology at High-Pressure Conditions by the Oscillating Drop Technique

An oscillating drop rheometer capable of operating under conditions of high pressure and high temperature has been built. The oscillating drop mechanism was able to support pressures as high as 1300 bar and successfully performed oscillations at constant pressure. Apparent elastic and viscous complex moduli were measured for a system of CO2 and synthetic seawater containing 100 ppm of a linear alkyl ethoxylate surfactant for different pressures and temperatures. The moduli had strong dependencies on both pressure and temperature. At temperatures of 40 and 80 °C, the apparent elastic modulus passed through a maximum for pressures between 100 and 300 bar. The harmonic distortion of the oscillations was calculated for all measurements, and it was found that drop oscillations below ca. 2.6 µL caused distortions above 10% due to a mechanical backlash of the motor.

Point-of-Care Strategies Applied to Malaria Diagnosis

Rapid and specific diagnosis of malaria remains one of the main strategies to fight the disease. The diagnosis is made primarily by the simple and low-cost thick drop technique, considered the gold standard test. However, the requirement for good quality microscopes and well-trained personnel often lead to inaccurate diagnosis, especially in cases of mixed infections or low parasitemia. Although PCR-based tests can help in these situations, this technique requires large and sensitive equipments, being unsuitable for point of care (POC) settings. A myriad of POC diagnostic tests have being developed in the last years, relying on molecular methods but also on novel strategies. New platforms, miniaturization techniques, and multiplexing possibilities promise great potential to improve disease diagnostics through fast and accurate detection of cases, even at remote places. Here, we will address the main POC strategies developed for the diagnosis of malaria, highlighting their strengths and weakness as POC applications.

Tear-drop technique in iliac screw placement: a technical analysis

Background Instrumentation of the lumbosacral region is one of the more challenging regions due to the complex anatomical structures and biomechanical forces. Screw insertion can be done both navigated and based on X-ray verification. In this study, we demonstrate a fast and reliable open, low exposure X-ray-guided technique of iliac screw placement. Methods Between October 2016 and August 2019, 48 patients underwent sacropelvic fixation in tear-drop technique. Screw insertion was performed in open technique by using an X-ray converter angulated 25-30° in coronal and sagittal view. The anatomical insertion point was the posterior superior iliac spine. Verification of correct screw placement was done by intraoperative 3D scan. Results In total, 95 iliac screws were placed in tear-drop technique with a correct placement in 98.1%. Conclusions The tear-drop technique showed a proper screw position in the intraoperative 3D scan and therefore may be considered an alternative technique to the navigated screw placement.

Aggregate stability of cultivated vineyard soils with high rock fragment content in the Mosel area, Germany

<p>Within the European project Diverfarming (Horizon 2020, no 728003), which investigates crop diversification and low-input farming across Europe, we study the aggregate stability variability of soils with high rock fragment content on steep sloping vineyards in the upper Saar valley of the Mosel area (Wawern, Rhineland-Palatinate, Germany).</p><p>In the framework of the case study researched by Trier University and their partners, aromatic herbs (Oregano and Thyme) are planted in rows underneath the grapevines to minimize soil erosion, suppress unwanted weeds and to be harvested for further use. Additionally, this cultivation affects different soil characteristics such as aggregate stability.</p><p>We analyse the aggregate stability using and comparing three different methods:</p><ul><li>wet sieving which is executed in two different ways – slaked and rewetted treatment,</li> <li>percolation method and</li> <li>single drop technique.</li> </ul><p>Aim of the study is to understand the effect of soil treatments underneath the grapevines, and to identify the method(s) being able to quantify the differences best.</p><p>Regarding the different methods, first results indicate that the quantified aggregate stabilities of each method are comparable. With this, we could identify differences between uncultivated rows (control areas), and the rows intercropped with aromatic herbs. In the latter ones, the aggregate stability underneath the grapevines is affected positively. Furthermore, there is a clear difference between slaked and rewetted treatment within the wet sieving method, where less stable aggregates are isolated.</p><p>The results indicate that the accomplished management (vine intercropped with Oregano and Thyme) improves the aggregate stability and therefore it improves the soil quality in general.</p>