scholarly journals Smartphone-Assisted Protein to Creatinine Ratio Determination on a Single Paper-Based Analytical Device

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6282
Author(s):  
Izabela Lewińska ◽  
Karolina Kurdziałek ◽  
Łukasz Tymecki
Keyword(s):  
Limit Of Detection ◽  
Signal Acquisition ◽  
Creatinine Ratio ◽  
Long Term Stability ◽  
Recovery Study ◽  
Artificial Urine ◽  
Ratio Determination ◽  
The One ◽  
Protein Assays

Proteinuria is a condition in which an excessive amount of protein is excreted in urine. It is, among others, an indicator of kidney disease or risk of cardiovascular disease. Rapid and reliable diagnosis and monitoring of proteinuria is of great importance for both patients and their physicians. For that reason, a paper-based sensor for proteinuria diagnosis was designed, optimized, and validated utilizing smartphone-assisted signal acquisition. In the first step, a few commonly employed protein assays were optimized and compared in terms of analytical performance on paper matrix. The tetrabromophenol blue method was selected as the one providing a sufficiently low limit of detection (39 mg·L−1) on the one hand and appropriate long-term stability (up to 3 months) on the other hand. The optimized assay was employed for protein-to-creatinine ratio (PCR) determination on a single paper-based sensor. For both analytes the linear ranges were within the clinically relevant range. The analytical usefulness of the developed sensors was demonstrated by a PCR recovery study in artificial urine. The obtained PCR recoveries were from ca. 80 to 150%.

scholarly journals Electret Filters—From the Influence of Discharging Methods to Optimization Potential

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 65
Author(s):  
Maximilian Kerner ◽  
Kilian Schmidt ◽  
Stefan Schumacher ◽  
Christof Asbach ◽  
Sergiy Antonyuk
Keyword(s):  
Fine Particles ◽  
Operating Time ◽  
Filtration Efficiency ◽  
Long Term Stability ◽  
Aerosol Filtration ◽  
Charge Decay ◽  
The One ◽  
Testing Standards ◽  
Discharge Efficiency

Electret filters are electrostatically charged nonwovens which are commonly used in aerosol filtration to remove fine particles from gases. It is known that the charge and thus also the filtration efficiency can degrade over time. Thus, many testing standards require to remove the charge by treatment with liquid isopropanol (IPA) or IPA-saturated air. However, the parameters influencing this discharge have not been completely clarified yet. The aim of this work was, on the one hand, to experimentally investigate the influence of the IPA treatment on different electret filters and, on the other hand, to show the optimization potential of electret filters with respect to efficiency and long-term stability by numerical simulations. The experiments revealed that the air permeability is a central influencing parameter. Small pores lead to a reduced discharge efficiency using liquid IPA, while both treatment methods are suitable for larger pores. The simulations showed that a homogeneous charge distribution within the filter depth is advantageous for the initial performance. In contrast, charge penetrating deeper in the filter medium delays the charge decay and thus increases the operating time, with the trade-off of a lower initial performance.

Synthesis of Nanosized Polymer Particles in Nonaqueous Emulsion

2013 ◽  
Vol 1546 ◽  
Author(s):  
Robert Dorresteijn ◽  
Robert Haschick ◽  
Kevin Müller ◽  
Markus Klapper ◽  
Klaus Müllen
Keyword(s):  
Ring Opening ◽  
Continuous Phase ◽  
Size Distributions ◽  
Aqueous Emulsion ◽  
Long Term Stability ◽  
Dispersed Particles ◽  
One Step ◽  
Moisture Sensitive ◽  
The One

ABSTRACTIn nonaqueous emulsion, moisture-sensitive polymerizations are performed in order to generate nanoparticles, which are not accessible by common aqueous emulsion polymerization. A nonaqueous emulsion, consisting of two immiscible aprotic organic solvents, is stabilized by amphiphilic block copolymers, such as PIb-PEO or PIb-PMMA copolymer, and lead to formation of nanosized dispersed droplets. They act as dispersed “nanoreactors” for the one-step synthesis of poly(urethane) nanoparticles in a polyadditon reaction as well as poly(L-lactide) nanoparticles through ring-opening polymerization, catalyzed by a moisture-sensitive catalyst. The well-dispersed particles possess average diameters below 100 nm and have narrow size distributions owing to the long-term stability of the dispersed droplets in the continuous phase.

scholarly journals Highly Responsive and Ultrasensitive Non-Enzymatic Electrochemical Glucose Sensor Based on Au Foam

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1203 ◽  
Author(s):  
Nannan Shen ◽  
Haijun Xu ◽  
Weichen Zhao ◽  
Yongmei Zhao ◽  
Xin Zhang
Keyword(s):  
High Selectivity ◽  
Glucose Sensor ◽  
Limit Of Detection ◽  
Surface Enhanced Raman Spectroscopy ◽  
Au Nanoparticle ◽  
Quantitative Detection ◽  
Term Stability ◽  
Long Term Stability ◽  
Surface Enhanced Raman

Glucose concentration is an important physiological index, therefore methods for sensitive detection of glucose are important. In this study, Au foam was prepared by electrodeposition with a dynamic gas template on an Au nanoparticle/Si substrate. The Au foam showed ultrasensitivity, high selectivity, and long-term stability in the quantitative detection of glucose. The foam was used as an electrode, and the amperometric response indicated excellent catalytic activity in glucose oxidation, with a linear response across the concentration range 0.5 μM to 12 mM, and a limit of detection of 0.14 μM. High selectivity for interfering molecules at six times the normal level and long-term stability for 30 days were obtained. The results for electrochemical detection with Au foam of glucose in human serum were consistent with those obtained with a sensor based on surface-enhanced Raman spectroscopy and a commercial sensor. This proves that this method can be used with real samples. These results show that Au foam has great potential for use as a non-enzymatic glucose sensor.

scholarly journals A Miniaturised, Fully Integrated NDIR CO2 Sensor On-Chip

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5347
Author(s):  
Xiaoning Jia ◽  
Joris Roels ◽  
Roel Baets ◽  
Gunther Roelkens
Keyword(s):  
Water Vapor ◽  
Limit Of Detection ◽  
Wafer Level ◽  
Water Vapor Absorption ◽  
Optical Source ◽  
Fully Integrated ◽  
Term Stability ◽  
Long Term Stability ◽  
Co2 Sensor

In this paper, we present a fully integrated Non-dispersive Infrared (NDIR) CO2 sensor implemented on a silicon chip. The sensor is based on an integrating cylinder with access waveguides. A mid-IR LED is used as the optical source, and two mid-IR photodiodes are used as detectors. The fully integrated sensor is formed by wafer bonding of two silicon substrates. The fabricated sensor was evaluated by performing a CO2 concentration measurement, showing a limit of detection of ∼750 ppm. The cross-sensitivity of the sensor to water vapor was studied both experimentally and numerically. No notable water interference was observed in the experimental characterizations. Numerical simulations showed that the transmission change induced by water vapor absorption is much smaller than the detection limit of the sensor. A qualitative analysis on the long term stability of the sensor revealed that the long term stability of the sensor is subject to the temperature fluctuations in the laboratory. The use of relatively cheap LED and photodiodes bare chips, together with the wafer-level fabrication process of the sensor provides the potential for a low cost, highly miniaturized NDIR CO2 sensor.

An effective and sensitive environmental pollutant sensor for pymetrozine

2020 ◽  
Author(s):  
Yudong Gao ◽  
Huimin Li ◽  
Yapan Shi
Keyword(s):  
Limit Of Detection ◽  
Single Walled Carbon Nanotubes ◽  
Environmental Pollutant ◽  
Voltammetric Sensor ◽  
Modified Glassy Carbon Electrode ◽  
Long Term Stability ◽  
Walled Carbon Nanotubes ◽  
Electrochemistry Behavior

Abstract Pymetrozine plays an important role in agriculture safety supervision. Accurate and rapid detection of pymetrozine in real sample is count for much as this is the significant prerequisite for its effective monitoring. An effective and sensitive voltammetric sensor, based on single-walled carbon nanotubes (SWCNT) composite poly(L-arginine) film modified glassy carbon electrode, was fabricated, and used for determination of pesticide pymetrozine. Results suggests that the poly(L-arginine)/SWCNT modified electrode exhibited a very low limit of detection. In addition, selectivity, long-term stability, and practical applicability of the developed sensor were evaluated. Hence, the developed poly(L-arginine)/SWCNT/GCE displayed excellent electrochemistry behavior towards the sensing of pymetrozine with good sensitivity, selectivity, and reproducibility. The detection technique successfully achieved the determination of pymetrozine in the concentration range 0.05μM ∼1.0μM with the detection limits of 17 nM (S/N=3).

scholarly journals Variance and invariance of neuronal long-term representations

2017 ◽  
Vol 372 (1715) ◽  
pp. 20160161 ◽  
Author(s):  
Claudia Clopath ◽  
Tobias Bonhoeffer ◽  
Mark Hübener ◽  
Tobias Rose
Keyword(s):  
Sensory Input ◽  
Cell Activity ◽  
Population Level ◽  
Cell Types ◽  
Sensory Experience ◽  
Homeostatic Plasticity ◽  
Long Term Stability ◽  
Brain Extracts ◽  
The One

The brain extracts behaviourally relevant sensory input to produce appropriate motor output. On the one hand, our constantly changing environment requires this transformation to be plastic. On the other hand, plasticity is thought to be balanced by mechanisms ensuring constancy of neuronal representations in order to achieve stable behavioural performance. Yet, prominent changes in synaptic strength and connectivity also occur during normal sensory experience, indicating a certain degree of constitutive plasticity. This raises the question of how stable neuronal representations are on the population level and also on the single neuron level. Here, we review recent data from longitudinal electrophysiological and optical recordings of single-cell activity that assess the long-term stability of neuronal stimulus selectivities under conditions of constant sensory experience, during learning, and after reversible modification of sensory input. The emerging picture is that neuronal representations are stabilized by behavioural relevance and that the degree of long-term tuning stability and perturbation resistance directly relates to the functional role of the respective neurons, cell types and circuits. Using a ‘toy’ model, we show that stable baseline representations and precise recovery from perturbations in visual cortex could arise from a ‘backbone’ of strong recurrent connectivity between similarly tuned cells together with a small number of ‘anchor’ neurons exempt from plastic changes. This article is part of the themed issue ‘Integrating Hebbian and homeostatic plasticity’.

scholarly journals Long-term monitoring with spring-based gravimeters: tilt-control benefits and application to the Rochefort Cave Laboratory (Belgium)

2020 ◽  
Author(s):  
Benjamin Fores ◽  
Arnaud Watlet ◽  
Michel Van Camp ◽  
Olivier Francis
Keyword(s):  
Linear Drift ◽  
Term Stability ◽  
Long Term Stability ◽  
New Information ◽  
Non Linear ◽  
Long Term Monitoring ◽  
The One ◽  
Term Monitoring ◽  
Local Hydrology

<p>Spring-based gravimeters are light and easy to install, with a precision around 5 μGal/√Hz. However, they are still not used for long-term gravity monitoring. The main reason for that is the non-linear drift of those instruments, which is very difficult to correct without removing geophysical signals. We will show that when the tilt is actively controlled, a gPhone spring-based gravimeter shows a quasi-linear drift and can reach a long-term stability at the µGal level.</p><p>This allows experiments such as the one in the Rochefort Cave Laboratory (Belgium). Thanks to the size of the gPhone and its low facility requirements, a monitoring from inside a cave was possible. Coupled with another gravity monitoring at the surface, it reveals new information on the local hydrology of this karstic site.</p>

scholarly journals The local help network to the homeless: case study of the city of koper, Slovenia

2014 ◽  
Vol 53 (2) ◽  
pp. 199-208
Author(s):  
Blaž Matija Geršak ◽  
Klara Praprotnik ◽  
Milan Krek
Keyword(s):  
Social Acceptance ◽  
The Other ◽  
Red Cross ◽  
Short Term ◽  
Staff Members ◽  
Long Term Stability ◽  
The One ◽  
The City

Abstract Aim: To present the work of professionals and volunteers of the local help network that revolves around trying to help the homeless and to stimulate readers to critically assess the possible methods aimed towards the successful integration of those people into society. Methods: In the city of Koper, we visited five governmental (GOs) and non-governmental organisations (NGOs): Red Cross Koper, Daybreak Association, Center for Social Work Koper, Diocesan Caritas Koper and Koper Prison; and interviewed 3-10 staff members at each organisation. Results: For each organisation, we described its duties and activities, including its interconnection with other organisations, methods of integrating the homeless into the society and the personal thoughts of its staff members. Conclusions: Both GOs and NGOs are necessary for providing effective assistance to people in need. NGOs excel at quickly responding to immediate needs. Their programs are usually implemented only as short-term resolutions. GOs on the other hand require a longer time to implement their concepts. Nonetheless, in contrast to NGO projects, they provide long-term stability. Even though people from remote parts of the society usually cooperate, the efforts of those who work with them are nothing short of exerting. They strive to achieve a general social acceptance of their ward population, which is the one thing those people need the most. Since only the society is truly capable of offering them a firm stepping stone towards escaping from the vicious circle in which they stray.

Middle East Islamist movements fragment under pressure

2015 ◽  
Keyword(s):  
Political Islam ◽  
The Political ◽  
Islamic State ◽  
Content Type ◽  
Long Term Stability ◽  
Sudden Rise ◽  
The One ◽  
State Group ◽  
Islamist Movements

Significance Almost two years on from Morsi's removal from office in 2013 mainstream Islamist movements in the region find themselves caught between an authoritarian crackdown led by Egypt and the Gulf on the one hand, and the sudden rise of Islamic State group (ISG) on the other. With political participation discredited, these two pressures are forcing Muslim Brotherhood-inspired movements to revise ideology and strategy as they compete to maintain and expand their constituencies. Impacts Mainstream Islamists will remain a significant political force in the region, but take years to regroup. Long-term stability will depend on allowing non-violent Islamists access to the political sphere. Younger Islamists will be increasingly attracted to radical ideologies. Egypt's slide into a more oppressive police state will continue. Saudi Arabia has put aside differences with Qatar and Turkey over political Islam for now -- but the dispute could resurface.

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