scholarly journals Improved Measurement Performance for the Sharp GP2Y1010 Dust Sensor: Reduction of Noise

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 775
Author(s):  
Jonathan E. Thompson
Keyword(s):  
Electromagnetic Interference ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Temporal Distribution ◽  
Urban Centers ◽  
Limits Of Detection ◽  
Pulse Delay ◽  
Particulate Pollution ◽  
Pollution Levels ◽  
Sensor Reduction

Sharp GP2Y1010 dust sensors are increasingly being used within distributed sensing networks and for personal monitoring of exposure to particulate matter (PM) pollution. These dust sensors offer an easy-to-use solution at an excellent price point; however, the sensors are known to offer limited dynamic range and poor limits of detection (L.O.D.), often >15 μg m−3. The latter figure of merit precludes the use of this inexpensive line of dust sensors for monitoring PM2.5 levels in environments within which particulate pollution levels are low. This manuscript presents a description of the fabrication and circuit used in the Sharp GP2Y1010 dust sensor and reports several effective strategies to minimize noise and maximize limits of detection for PM. It was found that measurement noise is primarily introduced within the photodiode detection circuitry, and that electromagnetic interference can influence dust sensor signals dramatically. Through optimization of the external capacitor and resistor used in the LED drive circuit—and the inter-pulse delay, electromagnetic shielding, and data acquisition strategy—noise was reduced approximately tenfold, leading to a projected noise equivalent limit of detection of 3.1 μg m−3. Strategies developed within this manuscript will allow improved limits of detection for these inexpensive sensors, and further enable research toward unraveling the spatial and temporal distribution of PM within buildings and urban centers—as well as an improved understanding of effect of PM on human health.

scholarly journals Contamination of Heavy Metals, Polychlorinated Dibenzo-p-Dioxins/Furans and Dioxin-Like Polychlorinated Biphenyls in Wharf Roach Ligia spp. In Japanese Intertidal and Supratidal Zones

2021 ◽  
Vol 11 (4) ◽  
pp. 1856
Author(s):  
Masato Honda ◽  
Xuchun Qiu ◽  
Suzanne Lydia Undap ◽  
Takeshi Kimura ◽  
Tsuguhide Hori ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Polychlorinated Biphenyls ◽  
Limit Of Detection ◽  
Environmental Pollutants ◽  
Dry Weight ◽  
Polychlorinated Dibenzofurans ◽  
Environmental Indicator ◽  
Pollution Levels ◽  
Copper Zinc ◽  
Total Concentrations

We investigated the pollution levels of 6 heavy metals and 29 dioxins (polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs)) in intertidal and supratidal zones by using wharf roaches (Ligia spp.) collected from 12 sampling sites on the coast of Northeast Japan from November 2011 to June 2012. The total concentrations of heavy metals ranged from 177 to 377 µg/g-dry weight (dw), and the predominant metals were copper, zinc, and aluminum. The order of the detected level of heavy metals was zinc > aluminum > copper > cadmium > lead > chromium, and this trend was similar to a previous report. The total toxic equivalent (TEQ) value of the PCDD/Fs ranged from less than the limit of detection (<LOD) to 2.33 pg-TEQ/g-dw, and the predominant congener was octachlorodibenzodioxin (<LOD to 110 pg/g-dw). Compared with PCDD/Fs, DL-PCBs were detected at a predominantly higher level (total TEQ value: 0.64–27.79 pg-TEQ/g-dw). Detected levels of dioxins, especially DL-PCBs in the wharf roach, were like those in the bivalves. These results indicate that the wharf roach could reflect heavy metals and dioxin pollution in the supratidal zones and is a suitable environmental indicator for these environmental pollutants. This is the first study to investigate heavy metals, PCDD/Fs, and DL-PCBs pollution in coastal isopods in Japan.

scholarly journals An Electrochemical Strategy for the Simultaneous Detection of Doxorubicin and Simvastatin for Their Potential Use in the Treatment of Cancer

Biosensors ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Iulia Rus ◽  
Mihaela Tertiș ◽  
Cristina Barbălată ◽  
Alina Porfire ◽  
Ioan Tomuță ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Electrolyte Solution ◽  
Electrode Material ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Simultaneous Detection ◽  
Linear Sweep Voltammetry ◽  
Pharmaceutical Formulations ◽  
Promising Tool ◽  
Scan Rate

The aim of this study was to develop a disposable, simple, fast, and sensitive sensor for the simultaneous electrochemical detection of doxorubicin (DOX) and simvastatin (SMV), which could be used in preclinical studies for the development of new pharmaceutical formulations for drug delivery. Firstly, the electrochemical behavior of each molecule was analyzed regarding the influence of electrode material, electrolyte solution, and scan rate. After this, the proper electrode material, electrolyte solution, and scan rate for both active substances were chosen, and a linear sweep voltammetry procedure was optimized for simultaneous detection. Two chronoamperometry procedures were tested, one for the detection of DOX in the presence of SMV, and the other one for the detection of DOX and SMV together. Finally, calibration curves for DOX and SMV in the presence of each other were obtained using both electrochemical methods and the results were compared. The use of amperometry allowed for a better limit of detection (DOX: 0.1 μg/mL; SMV: 0.7 μg/mL) than the one obtained in voltammetry (1.5 μg/mL for both drugs). The limits of quantification using amperometry were 0.5 μg/mL for DOX (dynamic range: 0.5–65 μg/mL) and 2 μg/mL for SMV (dynamic range: 2–65 μg/mL), while using voltammetry 1 μg/mL was obtained for DOX (dynamic range: 1–100 μg/mL) and 5 μg/mL for SMV (dynamic range: 5–100 μg/mL). This detection strategy represents a promising tool for the analysis of new pharmaceutical formulations for targeted drug delivery containing both drugs, whose association was proven to bring benefits in the treatment of cancer.

TREMOR: A Wireless MEMS Accelerograph for Dense Arrays

2005 ◽  
Vol 21 (1) ◽  
pp. 91-124 ◽  
Author(s):  
John R. Evans ◽  
Robert H. Hamstra ◽  
Christoph Kündig ◽  
Patrick Camina ◽  
John A. Rogers
Keyword(s):  
Spatial Resolution ◽  
Dynamic Range ◽  
Strong Motion ◽  
The United States ◽  
Companion Paper ◽  
Low Noise ◽  
Practical Reasons ◽  
Wireless Internet ◽  
Urban Centers ◽  
Strong Motion Network

The ability of a strong-motion network to resolve wavefields can be described on three axes: frequency, amplitude, and space. While the need for spatial resolution is apparent, for practical reasons that axis is often neglected. TREMOR is a MEMS-based accelerograph using wireless Internet to minimize lifecycle cost. TREMOR instruments can economically augment traditional ones, residing between them to improve spatial resolution. The TREMOR instrument described here has dynamic range of 96 dB between ±2 g, or 102 dB between ±4 g. It is linear to <1% of full scale (FS), with a response function effectively shaped electronically. We developed an economical, very low noise, accurate (<1%FS) temperature compensation method. Displacement is easily recovered to 10-cm accuracy at full bandwidth, and better with care. We deployed prototype instruments in Oakland, California, beginning in 1998, with 13 now at mean spacing of ∼3 km—one of the most densely instrumented urban centers in the United States. This array is among the quickest in returning (PGA, PGV, Sa) vectors to ShakeMap, ∼75 to 100 s. Some 13 events have been recorded. A ShakeMap and an example of spatial variability are shown. Extensive tests of the prototypes for a commercial instrument are described here and in a companion paper.

scholarly journals Composition, Sources, and Distribution of PM2.5 Saccharides in a Coastal Urban Site of China

Atmosphere ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 274 ◽  
Author(s):  
Mengxin Xiao ◽  
Qiongzhen Wang ◽  
Xiaofei Qin ◽  
Guangyuan Yu ◽  
Congrui Deng
Keyword(s):  
Biomass Burning ◽  
Biological Activities ◽  
Process Analysis ◽  
Fungal Spores ◽  
Temporal Distribution ◽  
Urban Site ◽  
Pollution Levels ◽  
Haze Pollution ◽  
Wide Range ◽  
High Level

The characteristics of biogenic aerosols in an urban area were explored by determining the composition and temporal distribution of saccharides in PM2.5 in Shanghai. The total saccharides showed a wide range of 9.4 ng/m3 to 1652.9 ng/m3, with the averaged concentrations of 133.1 ng/m3, 267.5 ng/m3, 265.1 ng/m3, and 674.4 ng/m3 in spring, summer, autumn, and winter, respectively. The saccharides include anhydrosaccharides (levoglucosan and mannosan), which were higher in cold seasons due to the increased biomass burning; saccharide alcohols (mannitol, arabitol, sorbitol); and monosaccharides (fructose, glucose), which were more abundant in warm seasons and attributed to the biological emissions. Through positive matrix factorization (PMF) analysis, four emission sources of saccharides were resolved, including biomass burning, fungal spores, plant decomposition, and pollen. Moreover, the process analysis of high concentrations of leveglucosan was conducted by backward trajectory and fire points. We found that concentrations of anhydrosaccharides were relatively stable under different pollution levels, while saccharide alcohols exhibited an obvious decrease with the concentration of PM2.5, indicating that biomass burning was not the core reason for heavy haze pollution. However, high level PM2.5 pollution might inhibit the effects of biological activities.

scholarly journals The Relationship between Particulate Pollution Levels in Australian Cities, Meteorology, and Landscape Fire Activity Detected from MODIS Hotspots

PLoS ONE ◽  
2012 ◽  
Vol 7 (10) ◽  
pp. e47327 ◽  
Author(s):  
Owen F. Price ◽  
Grant J. Williamson ◽  
Sarah B. Henderson ◽  
Fay Johnston ◽  
David M. J. S. Bowman
Keyword(s):  
Particulate Pollution ◽  
Pollution Levels ◽  
Fire Activity ◽  
The Relationship

scholarly journals Relations between demographic, geographic, and environmental statistics, and the spread of novel coronavirus disease (COVID-19) in Italy

2020 ◽  
Author(s):  
Alessandro Rovetta ◽  
Lucia Castaldo
Keyword(s):  
Normal Distribution ◽  
Strong Correlation ◽  
Demographic Data ◽  
Population Number ◽  
Environmental Statistics ◽  
Particulate Pollution ◽  
Pollution Levels ◽  
Awareness Campaigns ◽  
Novel Coronavirus ◽  
Pm2.5 And Pm10

BACKGROUND: Since January 2020, the COVID-19 pandemic has raged around the world, causing nearly a million deaths and hundreds of severe economic crises. In this scenario, Italy has been one of the most affected countries. OBJECTIVE: This study investigated significant correlations between COVID-19 cases and demographic, geographical, and environmental statistics of each Italian region from February 26 to August 12, 2020. We further investigated the link between the spread of SARS-CoV-2 and particulate matter (PM) 2.5 and 10 concentrations before the lockdown in Lombardy. METHODS: All demographic data were obtained from the AdminStat Italia website, and geographic data were from the Il Meteo website. The collection frequency was one week. Data on PM2.5 and PM10 average daily concentrations were collected from previously published articles. We used Pearson's coefficients to correlate the quantities that followed a normal distribution, and Spearman's coefficient to correlate quantities that did not follow a normal distribution. RESULTS: We found significant strong correlations between COVID-19 cases and population number in 60.0% of the regions. We also found a significant strong correlation between the spread of SARS-CoV-2 in the various regions and their latitude, and with the historical averages (last 30 years) of their minimum temperatures. We identified a significant strong correlation between the number of COVID-19 cases until August 12 and the average daily concentrations of PM2.5 in Lombardy until February 29, 2020. No significant correlation with PM10 was found in the same periods. However, we found that 40 μg/m^3 for PM2.5 and 50 μg/m^3 PM10 are plausible thresholds beyond which particulate pollution clearly favors the spread of SARS-CoV-2. CONCLUSION: Since SARS-CoV-2 is correlated with historical minimum temperatures and PM10 and 2.5, health authorities are urged to monitor pollution levels and to invest in precautions for the arrival of autumn. Furthermore, we suggest creating awareness campaigns for the recirculation of air in enclosed places and to avoid exposure to the cold. KEYWORDS: COVID-19, Italy, Pandemic, Epidemiology, Coronavirus-2019

scholarly journals A novel online coupling of ion selective electrode with the flow injection system for the determination of vitamin B1

2016 ◽  
Vol 13 (2) ◽  
pp. 458-469
Author(s):  
Baghdad Science Journal
Keyword(s):  
Flow Injection ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Vitamin B1 ◽  
Pharmaceutical Formulations ◽  
Ion Selective Electrode ◽  
Injection System ◽  
Selective Electrode ◽  
Flow Injection System

A simple, fast, selective of a new flow injection analysis method coupled with potentiometric detection was used to determine vitamin B1 in pharmaceutical formulations via the prepared new selective membranes. Two electrodes were constructed for the determination of vitamin B1 based on the ion-pair vitamin B1-phosphotungestic acid (B1-PTA) in a poly (vinyl chloride) supported with a plasticized di-butyl phthalate (DBPH) and di-butyl phosphate (DBP). Applications of these ion selective electrodes for the determination of vitamin B1 in the pharmaceutical preparations for batch and flow injection systems were described. The ion selective membrane exhibited a near-Nernstian slope values 56.88 and 58.53 mV / decade, with the linear dynamic range of vitamin B1 was 5 x 10-5- 1 x 10-2 and 1 x 10-4-1 x 10-2 mol.L-1, in batch and FIA, respectively. The limit of detection was 3.5 x 10-5 and 9.5 x 10-5 mol.L-1, with the percentage linearity 98.85 and 95.22 in batch and FIA, respectively. The suggested ion selective electrode has been utilized perfection in the determination of vitamin B1 in pharmaceutical formulations using batch and flow injection system, respectively.

scholarly journals Application of biosynthesized metal nanoparticles in electrochemical sensors

2021 ◽  
pp. 77-77
Author(s):  
Totka Dodevska ◽  
Dobrin Hadzhiev ◽  
Ivan Shterev ◽  
Yanna Lazarova
Keyword(s):  
Green Synthesis ◽  
Metal Nanoparticles ◽  
Electrochemical Sensors ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Cost Effective ◽  
Electrochemical Sensing ◽  
Synthesis Methods ◽  
Range Limit ◽  
Wide Range

Recently, the development of eco-friendly, cost-effective and reliable methods for synthesis of metal nanoparticles has drawn a considerable attention. The so-called green synthesis, using mild reaction conditions and natural resources as plant extracts and microorganisms, has established as a convenient, sustainable, cheap and environmentally safe approach for synthesis of a wide range of nanomaterials. Over the past decade, biosynthesis is regarded as an important tool for reducing the harmful effects of traditional nanoparticle synthesis methods commonly used in laboratories and industry. This review emphasizes the significance of biosynthesized metal nanoparticles in the field of electrochemical sensing. There is increasing evidence that green synthesis of nanoparticles provides a new direction in designing of cost-effective, highly sensitive and selective electrode-catalysts applicable in food, clinical and environmental analysis. The article is based on 157 references and provided a detailed overview on the main approaches for green synthesis of metal nanoparticles and their applications in designing of electrochemical sensor devices. Important operational characteristics including sensitivity, dynamic range, limit of detection, as well as data on stability and reproducibility of sensors have also been covered. Keywords: biosynthesis; green synthesis; nanomaterials; nanotechnology; modified electrodes

scholarly journals Simultaneous Determination of Trace Mefenamic Acid in Pharmaceutical Samples via Flow Injection Fluorometry

2020 ◽  
Vol 10 (03) ◽  
pp. 395-401
Author(s):  
Mohammad K. Hammood ◽  
Maryam Hamed
Keyword(s):  
Flow Injection ◽  
Mefenamic Acid ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Basic Medium ◽  
Minimum Concentration ◽  
Pharmaceutical Samples ◽  
Fluorescence Measurements ◽  
532 Nm

Mefenamic acid belongs to non-steroidal anti-inflammatory drugs that are used widely for the treatment of analgesia. Our aim from this study is to establish a new assay for the quantitative determination of mefenamic acid (MFA) in the pharmaceutical sample by two sensitive and rapid flow injection-fluorometric methods. A homemade fluorometer was used in fluorescence measurements, which using solid-state laser diode 405 and 532 nm as a source, combined with a continuous flow injection technique. The first method depends on the effect of MFA on calcein blue (CLB) fluorescence at 405 nm. Another method is a study of rhodamine-6G (Rh-6G) fluorescence after adding MFA, and recording at 532 nm. Optimum parameters as fluorescent dye concentration, basic medium, flow rate, sample volume, purge time, and delay coil have been investigated. The dynamic range of MFA was 0.2 to 2 mmol.L-1; 0.5 to 2.3 mmol.L-1 with linearity percentage (% r2) 98.92 and 99.83%, for Rh-6G and CLB, respectively. Limit of detection at a minimum concentration in calibration curve 189.34 and 199.89 ng/sample, for Rh-6G and CLB, respectively. The comparison of developed methods with the classical method (UV-vis spectrophotometry) was achieved. The proposed methods were successfully applied for the determination of MFA in the pharmaceutical samples and can be used as an alternative method.

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