scholarly journals A Simple Method for the Detection of Biofilms Using a Heatable Capacitive Sensor Structure (CSS): Description, Proof of Concept, and Some Technical Improvements

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 445
Author(s):  
Kai-Uwe Zirk ◽  
Manuel Olze ◽  
Harald Pötzschke
Keyword(s):  
Printed Circuit Boards ◽  
Free Water ◽  
Spray Coating ◽  
Internal Surface ◽  
Capacitive Sensor ◽  
Simple Method ◽  
Realistic Condition ◽  
Main Challenge ◽  
Sensor Structure ◽  
The Difference

This article presents a novel method for the detection of biofilms based on a heatable, capacitive sensor structure (CSS). Biofilms are capable of strongly binding large amounts of water to their extracellular biopolymer matrix, which is detectable via its dielectric properties. A main challenge is to determine the difference between the inherent occurring presence of moisture in the ecosystem, which is necessary to form a biofilm and an actual formed biofilm. Therefore, the CSS is carefully heated to evaporate unbound surface moisture and determine whether there is a remaining residual alternation of the capacitance in comparison to the dry state. As a reproduceable substitute for complex, real biofilms, a hygroscopic, medical hydrogel-based on polysaccharides was used and applied by spray coating. Printed circuit boards (PCB) in different geometries and materials were used as CSS and compared in terms of their performance. A layer-thickness of 20 µm for the hydrogel coating to be sufficiently detected was defined as a realistic condition based on known values for real biofilms cited in literature. For this thickness a double-meander structure proves to be preferable over interdigitating and spiral geometries. It does offer a 30% lower, yet sufficient sensitivity, but shows advantages in manufacturing (one layer instead of two) and conductive heating capability. In the experiments, free water showed virtually no residual change, while the hydrogel-coated CSS still shows an approx. 300% higher value compared to a dry capacity. Yet, the overall small capacities of about 6–30 pF in dry state are difficult to measure and therefore sensitive to interferences and noise, which results in a high deviation. The principle of measurement can be evaluated as proofed by the carried out experiments, though offering room for improvement in the design of the study. The new method might be especially useful for pipes (e.g., hydrodynamically ineffective sensors installed in a pipe wall) if they at least are not permanently flooded with an aqueous medium, but can occasionally dry. If the internal surface is still only moist, it can be dried by initial heating.

Pump Performance Improvement by Restraining Back Flow in Screw-Type Centrifugal Pump

2005 ◽  
Vol 127 (4) ◽  
pp. 755-762 ◽  
Author(s):  
Yasushi Tatebayashi ◽  
Kazuhiro Tanaka ◽  
Toshio Kobayashi
Keyword(s):  
Pressure Fluctuations ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Simple Method ◽  
Back Flow ◽  
Pump Performance ◽  
Impeller Outlet ◽  
Pump Head ◽  
The Difference ◽  
Set Up

The authors have been investigating the various characteristics of screw-type centrifugal pumps, such as pressure fluctuations in impellers, flow patterns in volute casings, and pump performance in air-water two-phase flow conditions. During these investigations, numerical results of our investigations made it clear that three back flow regions existed in this type of pump. Among these, the back flow from the volute casing toward the impeller outlet was the most influential on the pump performance. Thus the most important factor to achieve higher pump performance was to reduce the influence of this back flow. One simple method was proposed to obtain the restraint of back flow and so as to improve the pump performance. This method was to set up a ringlike wall at the suction cover casing between the impeller outlet and the volute casing. Its effects on the flow pattern and the pump performance have been discussed and clarified to compare the calculated results with experimental results done under two conditions, namely, one with and one without this ring-type wall. The influence of wall’s height on the pump head was investigated by numerical simulations. In addition, the difference due to the wall’s effect was clarified to compare its effects on two kinds of volute casing. From the results obtained it can be said that restraining the back flow of such pumps was very important to achieve higher pump performance. Furthermore, another method was suggested to restrain back flow effectively. This method was to attach a wall at the trailing edge of impeller. This method was very useful for avoiding the congestion of solids because this wall was smaller than that used in the first method. The influence of these factors on the pump performance was also discussed by comparing simulated calculations with actual experiments.

Free Water Influence on the Dynamic Tensile Behaviour of Concrete

2011 ◽  
Vol 82 ◽  
pp. 45-50 ◽  
Author(s):  
Benjamin Erzar ◽  
Pascal Forquin
Keyword(s):  
Dynamic Behaviour ◽  
Free Water ◽  
Dynamic Strength ◽  
Fragmentation Process ◽  
Tensile Behaviour ◽  
Water Influence ◽  
Micro Cracks ◽  
The World ◽  
The Difference ◽  
Impact Experiments

Concrete is a material used all over the world for civil engineering but the mechanisms governing its dynamic behaviour are still not well understood. In this work, spalling tests and edge-on impact experiments have been used to determine the influence of the free-water contained in pores and micro-cracks on the dynamic strength and on the fragmentation process. Moreover, spalling tests have been also used to identify the main mechanisms leading to the difference of behaviour observed between wet and dry concrete.

Coating of Polystyrene Surface with REDV-Gelatin Conjugate for Selective Isolation of Endothelial Cells

2021 ◽  
Vol 904 ◽  
pp. 287-292
Author(s):  
Wan Song Zhang ◽  
Ya Jie Fu ◽  
Rui Wang ◽  
Xuan Hui Qiu ◽  
Ze Yuan Feng ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Function ◽  
Flow Cytometric Analysis ◽  
Internal Surface ◽  
Cost Effective ◽  
Cell Viability Assay ◽  
Simple Method ◽  
Migration Assay ◽  
Gelatin Coating

Endothelial cells (EC), which line the internal surface of blood vessels, play various essential roles in controlling vascular function. The mouse is an important animal model for the study of vascular biology and cardiovascular diseases. However, the isolation of primary EC from the murine aorta is challenging because they are readily contaminated by smooth muscle cells (SMC). A previous study developed a simple method to isolate murine EC from SMC. By taking advantage of the differential sedimentation rate between the two cells, the EC was selectively enriched with collagen-coated polystyrene surfaces. Our study further improved this method by introducing a biomimetic peptide REDV (Arg-Glu-Asp-Val), which may bind specifically to EC but not to SMC or fibroblasts. Firstly, REDV-gelatin conjugate was synthesized by using the amine-to-sulfhydryl crosslinker SMCC. REDV-gelatin coating was then prepared on polystyrene surfaces, and their affinities to EC and SMC were subsequently investigated. Fluorescence microscopy and flow cytometric analysis showed that EC adhesion to the gelatin coating was significantly promoted by REDV peptide conjugation. Moreover, cell migration assay and cell viability assay also showed that the conjugation of REDV does not affect EC migration, and this coating did not show cytotoxicity against EC. This gelatin-REDV coating provides a cost-effective and straightforward tool for isolating EC from SMC, which may facilitate in vitro investigations of EC from mice.

Identification of the best topology of delta configured three phase induction generator for distributed generation through experimental investigations

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Vanka Bala Murali Krishna ◽  
Sandeep Vuddanti
Keyword(s):  
Distributed Generation ◽  
Reactive Power ◽  
Voltage Regulation ◽  
Reactive Power Compensation ◽  
Induction Generator ◽  
Experimental Investigations ◽  
Small Scale ◽  
Empirical Formulas ◽  
Simple Method ◽  
Main Challenge

Abstract Research on Self –excited induction generator (SEIG) brings a lot of attentions in the last three decades as a promising solution in distributed generation systems with low cost investment. There are two important fixations to attend in the operation of SEIG based systems, a) excitation and b) voltage regulation. Many procedures are reported regarding selection of excitation capacitance in the literature, based on state-state analysis, dynamic modeling, empirical formulas and machine parameters which involve various levels of complexity in findings. Moreover, the voltage regulation is the main challenge in implementation of SEIG based isolated systems. To address this problem, many power electronic-based schemes are proposed in the literature and but these solutions have few demerits importantly that additional cost of equipment and troubles due to failure of protection schemes. In particular, the installation of SEIG takes place at small scale in kW range in remote/rural communities which should not face such shortcomings. Further in case of off-grid systems, the maximum loading is fixed based on connected rating of the generator. This paper presents the various methods to find excitation capacitance and illustrates an experimental investigation on different possible reactive power compensation methods of delta connected SEIG and aimed to identify a simple method for terminal voltage control without power electronics. In this experimental work, the prime-mover of the generator is a constant speed turbine, which is the emulation of a micro/pico hydro turbine. From the results, it is found that a simple delta connected excitation and delta configured reactive power compensation limits voltage regulation within ±6% while maintaining the frequency of ±1%, which make feasible of the operation successfully in remote electrification systems.

scholarly journals Sources and mechanisms of seawater freshening at the Tsivol’ki and Sedov’ bays (Novaya Zemlya): isotope (δD, δ18О) data

2019 ◽  
Vol 59 (6) ◽  
pp. 928-938
Author(s):  
E. O. Dubinina ◽  
S. A. Kossova ◽  
A. Yu. Miroshnikov
Keyword(s):  
Surface Waters ◽  
Water Exchange ◽  
Free Water ◽  
Kara Sea ◽  
River Waters ◽  
Fresh Waters ◽  
Novaya Zemlya ◽  
Deep Waters ◽  
Continental Runoff ◽  
The Difference

Three-year monitoring of isotope (D, 18О) parameters in the waters of the Sedov and Tsivolki bays (Novaya Zemlya) was carried out. The fresh waters of the bays are originated from several sources (continental runoff, precipitations, and waters going from the archipelago). The freshening extent and sources of fresh waters are different at the different depth. The D and 18О values varies only in the surface waters which contains more than 30% of fresh component. In 2015 the surface waters of Sedov bay were represented by Ob river waters, and the surface waters of Tsivolki bay were enriched by the runoff from Novaya Zemlya. Deep waters in both bays show signs of desalination by high latitude atmospheric precipitations. These waters can be transferred to the southeast coast of Novaya Zemlya through the trenches of St. Anne and Voronin. The difference in the freshening mechanisms of the waters of Sedov and Tsivolka bays is determined by different bottom morphologies and different degrees of free water exchange with the Kara Sea.

Pump Performance Improvement by Restraining Back Flow in Screw-Type Centrifugal Pump

2005 ◽  
Author(s):  
Yasushi Tatebayashi ◽  
Kazuhiro Tanaka ◽  
Toshio Kobayashi
Keyword(s):  
Pressure Fluctuations ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Simple Method ◽  
Back Flow ◽  
Pump Performance ◽  
Impeller Outlet ◽  
Pump Head ◽  
The Difference ◽  
Set Up

The authors have been investigating the various characteristics of screw-type centrifugal pumps, such as pressure fluctuations in impellers, flow patterns in volute casings, and pump performance in air-water two-phase flow conditions. During these investigations, numerical results of our investigations made it clear that three back flow regions existed in this type of pump. Among these, the back flow from the volute casing toward the impeller outlet was the most influential on the pump performance. Thus the most important factor to achieve higher pump performance was to reduce the influence of this back flow. One simple method was proposed to obtain the restraint of back flow and so as to improve the pump performance. This method was to set up a Ring-like wall at the suction cover casing between the impeller outlet and the volute casing. Its effects on the flow pattern and the pump performance have been discussed and clarified to compare the calculated results with experimental results done under two conditions — namely, one with and one without this Ring-type wall. The influence of wall’s height on the pump head was investigated by numerical simulations. In addition, the difference due to the wall’s effect was clarified to compare its effects on two kinds of volute casing. From the results obtained it can be said that restraining the back flow of such pumps was very important to achieve higher pump performance. Furthermore, another method was suggested to restrain back-flow effectively. This method was to attach a wall at the trailing edge of impeller. This method was very useful for avoiding the congestion of solids because this wall was smaller than that used in the first method. The influence of these factors on the pump performance was also discussed by comparing simulated calculations with actual experiments.

scholarly journals A Simple Method to Create Superhydrophobic Aluminium Surfaces

2012 ◽  
Vol 706-709 ◽  
pp. 2874-2879 ◽  
Author(s):  
R. Jafari ◽  
Masoud Farzaneh
Keyword(s):  
Contact Angle ◽  
Stearic Acid ◽  
Synergistic Effects ◽  
Low Cost ◽  
Contact Angle Hysteresis ◽  
Spray Coating ◽  
Superhydrophobic Surfaces ◽  
Water Contact ◽  
Simple Method ◽  
Static Contact

Superhydrophobic surfaces were prepared using a very simple and low-cost method by spray coating. A high static water contact angle of about 154° was obtained by deposition of stearic acid on an aluminium alloy. However, this coating demonstrated a high contact angle hysteresis (~ 30º). On the other hand, superhydrophobic surfaces with a static contact angle of about 162º and 158º, and a low contact angle hysteresis of about 3º and 5º were respectively obtained by incorporating nanoparticles of SiO2and CaCO3in stearic acid. The excellent resulting hydrophobicity is attributed to the synergistic effects of micro/nanoroughness and low surface energy. A study of the wettability of these surfaces at temperatures ranging from 20 to-10 °C showed that the superhydrophobic surface becomes rather hydrophobic at supercooled temperatures.

Knowledge Management and Software Development Organization

2017 ◽  
pp. 226-246 ◽  
Author(s):  
Marcello Chedid ◽  
Leonor Teixeira
Keyword(s):  
Knowledge Management ◽  
Software Development ◽  
Tacit Knowledge ◽  
Development Process ◽  
Management Process ◽  
Software Development Process ◽  
Development Organization ◽  
Main Challenge ◽  
The Difference ◽  
Knowledge Intensive

Software development organization (SDO) is a kind of knowledge-intensive business and their large majority is small and medium enterprise (SME) facing similar challenges of large ones. The diversity and complexity of the SDO environment makes knowledge the fundamental element in the software development process, which strengthens the importance of an effective knowledge management process. The software development process involves multidisciplinary teams, and the various working meetings that occur during a project are conducive to generate and share a lot of knowledge, in particular tacit knowledge. The use of a knowledge management process that enables to manage tacit knowledge will define the difference between a good SDO performance and the best SDO performance. This chapter aims to present an exploratory study based on literature review, with the aim of identifying the main challenge of knowledge management in the SDO context. The authors also aim to address some new research directions.

scholarly journals Reduced-Reflection Multilayer PCB Microstrip with Discontinuity Characterization

Electronics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1473
Author(s):  
Aleksandr Vasjanov ◽  
Vaidotas Barzdenas
Keyword(s):  
Printed Circuit Boards ◽  
Dielectric Material ◽  
Academic Research ◽  
System Level ◽  
Reference Plane ◽  
Impedance Change ◽  
Circuit Boards ◽  
Impedance Mismatch ◽  
The Difference ◽  
Technology And Communication

In the era of technology and communication, printed circuit boards (PCBs) can be found in a myriad of devices—from ordinary household items, to state of the art custom metrology equipment. Different types of component for wireless communications are available and come in various packages, supplied by multiple manufacturers. The signal landpads for some high-frequency connectors and components, encapsulated in larger packages, are usually wider than the controlled impedance trace, thereby introducing unwanted impedance mismatch and resulting in signal reflections. The component land pad and microstrip width a discrepancy issue can be found in both complex high-density industrial devices and system-level academic research papers. This paper addresses the topic of compensating discontinuities, introduced by signal pads, which are wider than the target impedance microstrip, characterizes the difference between the compensated and uncompensated microstrip with discontinuity, and proposes a generalized guideline on compensating for the introduced impedance change in multilayer PCBs. The compensation method is based upon carefully designing the stackup of the PCB allowing for a reference plane cutout under the discontinuity to even out the impedance mismatch. A 6-layer PCB with IT180A dielectric material containing three structures has been manufactured and characterized using an Agilent E8363B vector network analyzer (VNA). A 4–12 dB improvement in S11 response in the whole frequency range up to 10 GHz, compared to that when no compensation has been applied, was observed.

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