Sampling Bags Research Articles

Development of a wristband-type wearable device for the colorimetric detection of ammonia emanating from the human skin surface

Human skin gas is the term used to describe gas emanating from the human skin surface. Ammonia, one such gas, has a pungent odor affecting body odor. As ammonia’s dermal emission increases with physical load and/or psychological stress, the resulting body odor is called “fatigue odor.” Previously, human skin gases were collected via direct contact or headspace sampling, using a homemade sampling probe or bag and passive flux sampler. We developed a wristband-type wearable device for rapid, on-site detection of dermal ammonia based on headspace passive sampling coupled with Alizarin red as a pH indicator. Color change was measured with a colorimetric indicator tested in an exposure chamber and calibrated using dermal emission flux measured with a passive flux sampler. The indicator was developed as a tablet-like device comprising a polyethylene terephthalate body with a transparent window, detection sheet, diffuser, and disk with concentric spaces. The detection sheet was prepared by pipetting 50 μL 0.1 % Alizarin red–1 % glycerol into a methanol solution onto a cellulose filter paper and drying. The colorimetric indicator was placed on the skin surface using a wristband. For quantitative evaluation, the color-change amount was evaluated using color difference (ΔE*ab), which was calculated from L*, a*, and b* measured using a spectrophotometer. The colorimetric response to ammonia on the colorimetric indicator was evaluated by comparison with the conventional passive flux sampler. Good correlations were obtained between the color change amounts and those collected with the passive flux sampler. To simulate living human-skin conditions, the influence of temperature and humidity was also tested, and the effect on the passive indicator was clarified. Compared to conventional dermal ammonia-measuring methods, this newly developed passive indicator was more user-friendly because the results were obtained on-site without external evaluation. The passive indicator was also found to be an effective and simplified instrument for dermal ammonia measurements.

Novel field-portable high-pressure adsorbent tube sampler prototype for the direct in situ preconcentration of trace compounds in gases at their working pressures: application to biomethane.

In Europe, renewable energy gases such as biomethane are aimed at substituting natural gas provided their stringent compliance to natural gas quality standards stipulating maximal levels of several chemical trace compounds (TC). Preconcentration is generally required to detect TC and inasmuch as biomethane is compressed for injection in the natural gas grid, preconcentration is commonly either done by collecting the bulk pressurized gas in a high-pressure cylinder or by first depressurizing it to collect a bulk volume in e.g. a gas sampling bag. Such whole gas samples are then transported to the lab and transferred to a preconcentration unit, entailing contamination and TC loss risks. Therefore, here a novel handy field-portable device for the direct in situ high-pressure preconcentration of TC is presented, enabling to sample gases at pressures up to 200 bara through a self-assembled Tenax®TA + Carbopack™X multibed adsorbent tube. The effect of the gas sampling pressure on the preconcentration of TC on adsorbent tubes was evaluated using a synthetic gas mixture containing 41 halogenated volatile organic compounds each at 1 ppmmol in N2. At given normalized sampled volumes and in the pressure range 5–100 bara handled in French gas transport grids, the pressure had no influence on the preconcentration when the gas circulates through the adsorbent tubes and as long as the adsorbents are not saturated. Next, for the first time, a real biomethane stream was sampled using the novel direct high-pressure preconcentration method on Tenax®TA + Carbopack™X multibed adsorbent tubes, allowing to preconcentrate, in a single sampling run, a wide range of volatile organic TC. More than 26 distinct TC were detected, belonging to seven chemical families: alkenes, aromatics, alkanes (linear, cyclic and polycyclic), sulphur-compounds and terpenes, with linear alkanes (pentane, heptane, octane) and terpenes predominating. Semi-quantification indicated pentane, dimethylcyclopropane, hexane, heptane, octane, α-pinene and camphene are present at a ≤1 ppmmol concentration threshold in the biomethane.

Development of a Non-invasive Diagnostic Method for Esophageal Squamous Cell Carcinoma by Gas Chromatographic Analysis of Exhaled Breath.

Since esophageal carcinoma progresses asymptomatically, for many patients the disease is already advanced at the time of diagnosis. The main methods that are currently used to diagnose esophageal carcinoma are upper gastrointestinal radiographic contrast examinations and upper gastrointestinal endoscopy, but early discovery of this disease remains difficult. There is a need to develop a diagnostic method using biomarkers that is non-invasive while both highly sensitive and specific. Exhaled breath was collected from 17 patients with esophageal squamous cell carcinoma (ESCC), as well as 9 control subjects without history of any cancer. For each fasting subject, 1L of exhaled breath was collected in a gas sampling bag. Volatile organic compounds (VOCs) were then extracted from each sample using Solid phase micro-extraction (SPME) fibers and analyzed by gas chromatography-mass spectrometry (GC-MS). Levels of acetonitrile, acetic acid, acetone, and 2-butanone in exhaled breath were significantly higher in the patient group than in the control group (p = 0.0037, 0.0024, 0.0024 and 0.0037, respectively). ROC curves were drawn for these 4 VOCs, and the results for the area-under-the-curve (AUC) indicated that ESCC patients can be identified with a high probability of 0.93. We found distinctive VOCs in exhaled breath of ESCC patients. These VOCs have a potential as new clinical biomarkers for ESCC. The measurement of VOCs in exhaled breath may be a useful, non-invasive method for diagnosis of ESCC.

Renewable Activated Carbon Filters Bearing Photocatalytic Particles for Volatile Organic Compound Removal.

As interest in improving indoor air quality has increased, the development of long-lasting adsorbents that effectively and economically remove volatile organic compounds (VOCs) has become critical. In this study, TiO2-bearing activated carbon is introduced as a photocatalytic adsorbent in a renewable VOC filter. The activated carbon filter bearing TiO2 particles is prepared using the sol-gel method, followed by a spraying method. VOC adsorption and photocatalytic activity of the TiO2-bearing activated carbon are analyzed using a Tedlar bag sampling technique, using toluene and acetaldehyde as sample of VOC gas. Under ultraviolet-C (UV-C) irradiation for 22 h, the photocatalytic activity of TiO2 regenerates the VOC filters by 99 %. In addition, under UV-A and light-emitting diode, the TiO2-bearing activated carbon filters are regenerated by 60 % and 58 %, respectively, after 22 h. This result establishes its practical applicability as a renewable indoor VOC filter.

Tee-Shaped Sample Introduction Device Coupled with Direct Analysis in Real-Time Mass Spectrometry for Gaseous Analytes.

Ambient ionization mass spectrometry (AIMS) is simple to operate for analytes adsorbed on the surface of various shaped probes. However, gaseous substances or liquids that are easy to evaporate, diffuse, and escape in the atmosphere are harder to capture. In this work, a Tee-shaped sample introduction device coupled with direct analysis in real time mass spectrometry (DART-MS) is developed. The Tee-shaped device is placed between the DART ion source and the MS inlet with a heated sample transfer tube. Gaseous samples from either a Tedlar sampling bag or liquids evaporated from a graduated syringe were tested. The Tee-shaped device was used for several volatile organic compounds with a wide range of boiling points, and detection limits of ng/mL to fg/mL were obtained. To test the device for real-life samples, puff-by-puff analysis of a complex gaseous mainstream smoke was performed. Individual puffs can be analyzed rapidly, and there is no cross contamination between consecutive puffs. The dynamic changes of chemical components among different puffs for different types of cigarettes can be observed. This work provides a universal Tee-shaped sampling device to enhance AIMS for the analysis of volatile compounds and gases, which is adapted to different sampling modules applicable for various forms of samples. The device enables direct exploration of chemical components in complex gaseous samples without tedious sample preparation and time-consuming LC or GC separation.

The feasibility and temporal storability of gas phase standards of volatile organic compounds prepared through liquid phase vaporization in polyester aluminum bags at room temperature

Currently, the presence of many classes of volatile organic compounds (VOCs) in indoor air is well recognized. There is an impetus to accurately quantify airborne VOCs for the proper assessment of their human health risks. VOC standards prepared in a solvent are often vaporized in N2 gas-filled sampling bags for external calibration as the use of grab sampling bags is a common practice for the collection of real ambient air samples. Such practices can nontheless be subject to many sources of biases in their calibration (e.g., VOC chemical reaction with the solvent, adsorption on the bag interior surface, or leakage). The main goal of this work is to measure the temporal stability of 11 VOC targets (benzene, toluene, o-xylene, styrene, propionaldehyde, n-butyraldehyde, isovaleraldehyde, valeraldehyde, acrylonitrile, isoprene, and methyl ethyl ketone) selected in this research over 24 h which started 10 min after the injection and vaporization of liquid-phase standards (all prepared in methanol solvent) into polyester aluminum (PEA) bags containing 1 atm N2. Although all tested VOCs showed gradual decreases of their concentrations (e.g., >17% in 24 h), the aromatic hydrocarbon VOCs (namely BTXS) yielded the best relative recoveries (e.g., decreases of 11%–30% in 24 h) and relative errors (e.g., relative standard error (RSE) = 2.14–3.59%) in 5 replicate tests. A good linear relationship was established between the 24 h VOC relative recovery and molecular weight (R2 > 0.81). The results of this study offers valuable clues to properly reduce the bias in the calibration of gas-phase VOC standards when calibrating the system through the vaporization of liquid-phase VOC standards prepared in a solvent.

Polycyclic Aromatic Hydrocarbons and Some of Organochlorine Pesticide Residues and Health Risk Assessments in Commonly Consumed Teas in Jordan

During the year 2020, 60 samples of black and green tea bags were collected from Jordanian markets. The samples were subjected to multi-residue analysis for 16 carcinogenic polycyclic aromatic hydrocarbons (PAHs) which belong to the Environmental Protection Agency (EPA) priority pollutant list and 20 banned organochlorine pesticides (OCPs). A QuEChERs method was developed for the determination of 16 EPA PAHs and OCPs residues using hyphenated gas chromatography–mass spectrometry (GC–MS) for analysis. To minimize the colors of chlorophyll and carotenoids, the concentrated extracts were subjected to 10 mg of activated charcoal for further extraction. The QuEChERs technique has been validated, and the outcomes in terms of linearity, detection limits, quantitation limits, precision, and recovery have been satisfactory. On one hand, none of the examined black and green tea bag samples contained any of the studied OCPs, while the estimated quantities of PAHs, on the other hand, ranged from 280.03 to 486.46 µg kg−1, and the amounts of benzo[a]pyrene ranged from 4.85 to 8.56 µg kg−1. The light PAHs were predominant in both black and green tea samples (90%), while the contribution of heavy PAHs was much less significant (10%). The incremental lifetime cancer risk (ILCR) was evaluated, and the values for all tea samples have not exceeded the limit value of 10−6 but ranged from 4.17 × 10−8 to 0.0158 × 10−8, thus indicating a slight potential risk.

Experimental Investigation on Water Adsorption Using Laser Photoacoustic Spectroscopy and Numerical Simulations.

In the present research we propose a model to assess the water vapors adsorption capacity of a SiO2 trap in the breathing circuit, aiming to reduce the loading of interfering compounds in human breath samples. In this study we used photoacoustic spectroscopy to analyze the SiO2 adsorption of interfering compounds from human breath and numerical simulations to study the flow of expired breath gas through porous media. As a result, the highest adsorption rate was achieved with a flow rate of 300 sccm, while the lowest rate was achieved with a flow rate of 600 sccm. In the procedure of H2O removal from the human breath air samples, we determined a quantity of 213 cm3 SiO2 pearls to be used for a 750 mL sampling bag, in order to keep the detection of ethylene free of H2O interference. The data from this study encourages the premise that the SiO2 trap is efficient in the reduction of interfering compounds (like water vapors) from the human breath.

Sensitivity of secondary electrospray ionization mass spectrometry to a range of volatile organic compounds: Ligand switching ion chemistry and the influence of Zspray™ guiding electric fields.

Secondary electrospray ionization (SESI) is currently only semi-quantitative. In the Zspray™ arrangement of SESI-MS, the transfer of ions from near atmospheric pressure to a triple quadrupole is achieved by guiding electric fields that partially desolvate both reagent and analyte ions which must be understood. Also, to make SESI-MS more quantitative, the mechanisms and the kinetics of the reaction processes, especially ligand switching reactions of hydrated hydronium reagent ions, H3 O+ (H2 O)n , with volatile organic compound (VOC) molecules, need to be understood. A modified Zspray™ ESI ion source operating at sub-atmospheric pressure with analyte sample gas introduced via an inlet coaxial with the spray was used. Variation of the ion-guiding electric fields was used to reveal the degree of desolvation of both reagent and analyte ions. The instrument sensitivity was determined for several classes of VOCs by introducing bag samples of suitably varying concentrations as quantified on-line using selected ion flow tube MS. Electric field desolvation resulted in largely protonated VOCs, MH+ , and their monohydrates, MH+ H2 O, and for some VOCs proton-bound dimer ions, MH+ M, were formed. There was a highly linear response of the ion signal to the measured VOC sample concentration, which provided the instrument sensitivities, S, for 25 VOCs. The startling results show very wide variations in S from near 0 to 1 for hydrocarbons, and up to 100, on a relative scale, for polar compounds such as monoketones and unsaturated aldehydes. The complex ion chemistry occurring in the SESI ion source, largely involving gas-phase ligand switching, results in widely variable sensitivities for different classes of VOCs. The sensitivity is observed to depend on the dipole moment and proton affinity of the analyte VOC molecule, M, and to decrease with the observed fraction of MH+ H2 O, but other yet unrecognized factors must play a significant role.

Experimental methods to determine the performance of desiccant coated fixed-bed regenerators (FBRs)

Desiccant coated fixed-bed regenerators (FBRs) transfer heat and moisture between two airstreams having different temperature and humidity. The experiments on FBRs are challenging because of their transient nature of operation. Unlike other energy exchangers, FBRs do not attain a steady-state condition; instead, they reach a quasi-steady state where the humidity and temperature of the outlet air continuously vary with time. This paper shows that measuring the temperature and humidity of a time-varying airstream with temperature and humidity sensors may lead to errors in the effectiveness in the order of 15–20%. Meanwhile, the method proposed in this paper reduces errors to ±5–8%, which is comparable to the accepted uncertainties in steady-state test standards. The major contributions of this paper are: (i) development and verification of new experimental methods to determine the effectiveness of desiccant coated FBRs and (ii) verification of the bag sampling method (BSM) for humidity measurements proposed by test standards. The results are verified using a validated numerical model and a correlation from the literature.

Leaf litter and rock bag surveys allow for detection and DNA barcoding characterization of diet composition of dusky salamanders

Salamanders are vital components of many aquatic ecosystems food webs and are often found in diverse habitats, including both urban and semi-rural environments. The northern dusky salamander, Desmognathus fuscus is a common salamander found throughout the southeastern United States and is an important predator of aquatic macroinvertebrates. However, very little is known about either diet or suitable survey techniques for this species in human altered habitats, which may vary based on level of urbanization (e.g., are either spring-fed, derived from ponds, modified ditches, etc.). Therefore, we used multiple survey methods (leaf litter bags, novel rock bags, and quadrat sampling) to quantify relative abundance of D. fuscus on Wingate University's campus, in Wingate, North Carolina. We also collected and identified aquatic invertebrates from bag sampling and diet items obtained from gastric lavage of adult salamanders from quadrat sampling. Leaf litter bags contained the highest relative abundance of salamanders (47) compared to rock bags (14), with quadrat sampling yielding primarily adult salamanders. We noted a significant difference among our two sites sampled in salamander relative abundance (Man-Whitney U test = 67.5, p < 0.001), possibly due to reduced water quality, canopy cover, or less available habitat. Aquatic worms represented the most frequent potential food item sampled from both bag types (61.9%), followed by Diptera nymphs (13.7%). Potential food items from leaf and rock bags as well as gastric lavage samples collected from Desmognathus were further identified using DNA barcoding. These food items included a variety of both aquatic and terrestrial invertebrates (annelid worms, springtails, chironomids, carpenter ants, shore flies, wasps, and wood lice). These results indicate urban salamanders may forage both in the stream and in the riparian zone or advantageously consume insects which fall into the stream. This study adds to our body of knowledge on the ecology of salamanders in urban stream environments.

Modeling thermal inactivation of Salmonella Typhimurium in mash broiler feed

Feed hygienics is of increasing concern for poultry producers. This project included 2 studies to investigate kinetic parameters for inactivation of Salmonella Typhimurium in mash broiler feed heated at various temperatures. In study one, 2- and 5-g feed samples, contained in a sample bag, were inoculated with S. Typhimurium and submerged in a water bath heated to 90°C until internal temperatures of 75°, 80°, and 85°C were reached. In study two, 2-g of sample were inoculated with S. Typhimurium and submerged into a water bath set at 75°, 80°, 85°, 90°, and 95°C heated for 0 to 180 s. Feed sample and water bath temperature were monitored by thermocouples. Thermocouple data demonstrated 2- and 5-g samples achieved a 5-log reduction of S. Typhimurium when internal temperature of feed reached 80°C and 85°C, respectively. D-values for linear and Weibull models were calculated for the 5 temperatures. D-values of the linear model were 6.70, 8.83, 12.05, 13.91, and 24.40 s, and D-values for the Weibull model were 2.27, 3.67, 3.95, 4.68, and 7.63 s when heated to 95°, 90°, 85°, 80°, and 75°C. Individual temperature datasets were further analyzed using GinaFit software. As heating temperature decreased, Double-Weibull and Biphasic models fit all the thermal data, indicating that Salmonella could have generated 2 subpopulations with different thermoresistance. Similar to other thermal inactivation models, this study demonstrates that linear, Weibull, Double-Weibull, and Biphasic models could be used to predict thermal inactivation of Salmonella in mash broiler feed. These data may contribute to establishing feed mill microbiological safety standards and reducing Salmonella contamination in broiler feed.

Carbon isotopic characterisation and oxidation of UK landfill methane emissions by atmospheric measurements.

Biological oxidation of methane in landfill cover material can be calculated from the carbon isotopic signature (δ13CCH4) of emitted CH4. Enhanced microbial consumption of methane in the aerobic portion of the landfill cover is indicated by a shift to heavier (less depleted) isotopic values in the residual methane emitted to air. This study was conducted at four landfill sites in southwest England. Measurement of CH4 using a mobile vehicle mounted instrument at the four sites was coupled with Flexfoil bag sampling of ambient air for high-precision isotope analysis. Gas well collection systems were sampled to estimate landfill oxidised proportion. Closed or active status, seasonal variation, cap stripping and site closure impact on landfill isotopic signature were also assessed. The δ13CCH4 values ranged from -60 to -54‰, with an average value of -57±2‰. Methane emissions from active cells are more depleted in 13C than closed sites. Methane oxidation, estimated from the isotope fractionation, ranged from 2.6 to 38.2%, with mean values of 9.5% for active and 16.2% for closed landfills, indicating that oxidised proportion is highly site specific.

Quantification of volatile organic compounds by secondary electrospray ionization-high resolution mass spectrometry

Secondary electrospray ionization coupled with high resolution mass spectrometry (SESI-HRMS) is a direct mass spectrometry technique, which can identify trace volatile organic compounds (VOCs) in real time without sample pretreatment and chromatographic separation. SESI-HRMS has been successfully applied in multiple applications, including breath analysis, animals and plants VOCs emissions, analysis of headspace of cell cultures and indoor and outdoor air. The range of areas where the technique can potentially have a substantial impact is very broad. However, one critical aspect that requires further development to consolidate the technique is absolute quantification. Therefore, in this study we aim to develop a quantitative method for eight representative VOCs, including ketones (acetone, 2-butanone and 2-pentanone), alkenes (isoprene and α-terpinene) and aromatics (toluene, styrene and mesitylene). The mass spectrometric platform includes a commercial SESI source hyphenated with a Q-Exactive hybrid quadrupole Orbitrap high resolution mass spectrometer. Within the concentration range of 0–100 ppbv studied, the optimal coefficient of determination for linear regression (R2 = 0.993–0.999) between signal intensity and concentration is obtained in the range of 0–10 ppbv for all eight VOCs. The detection limits range between 3 (2-Pentanone) and 15 (Acetone) pptv. The intra-day (n = 10) and inter-day (n = 30) coefficients of variation (CV) are ≤ 6% and ≤10%, respectively. Finally the method is applied for the fast evaluation (<5 min) of different materials widely used for the collection, storage or pretreatment of gas sample. Better recovery of trace levels of eight VOCs is observed for PTFE gas sampling bag as compared to Nalophan and Tedlar bags; when Nafion tube is used to pretreat the gas sample, recovery of ≤50% are obtained for 2-pentanone, α-terpinene and all three aromatics.

A study on estimation of recovery rate of volatile fatty acids in livestock odor for storage time from PEA sampling bags

A study on estimation of recovery rate of volatile fatty acids in livestock odor for storage time from PEA sampling bags

A Study to Identify Correlation of Hematopoietic Progenitor Cell(XN-HPC) By Sysmex Cell Counters with Final Yield of CD34 + Stem Cells

Successful bone marrow transplantation depends on the collection and infusion of enough numbers of peripheral blood stem cells. Several predictors of stem cell yield are used now, including white blood cell (TLC) count and CD34 in peripheral blood. This study evaluated the utility of the new automated hematopoietic progenitor cell count(HPC) available on Sysmex XN hematology analyzers (XN-HPCs) in stem cell harvest. STUDY DESIGN AND METHODSThe characteristics of XN-HPC, CD34+ stem cells, and TLC analysis were compared using 217 matched peripheral blood and apheresis bag samples. RESULTSGood correlation was observed between HPC and CD34+ stem cell counts in peripheral blood (r = 0.90; slope, 0.82) and apheresis collections (r = 0.93; slope, 0.91). There is a good corelation that peripheral blood HPC and CD34 analysis showed ability to predict successful stem cell harvests (≥ 2 × 106 CD34+ cells/kg). Fixing a cutoff of 25 × 106 HPC/L, peripheral blood XN- HPC and CD34 analysis both showed negative predictive values (NPVs) of 100% and positive predictive values (PPVs) of 66% and 80%, respectively. In contrast, the correlation between peripheral blood TLC and CD34 analysis was poor (r = 0.39), and the peripheral blood WBC count (cutoff, 20 × 109/L) was a poor predictor of PBPC harvest (NPV 55%, PPV 38.7%). CONCLUSIONHematopoietic Progenitor cell (HPC) compares well with both peripheral blood and bag CD34 analysis and may act as a cheap surrogate marker for CD34 analysis to predict optimal timing of stem cell harvest especially in Autologous bone marrow transplant receipients.This will help us in reducing costs in a resource limited developing country like India. DisclosuresNo relevant conflicts of interest to declare.

Variability of micronutrient status and hazard potential in soils of six mapping units within Eastern part of Kogi state, Nigeria

Micronutrient imbalance in some soils is a major challenge for cultivation of crops. Hence the need to assess their status and variability in agricultural soils. The aim of this research was to assess the micro-nutrient status, variability and hazard potential in some soils within eastern part of kogi state of Nigeria. Six mapping units, 2a, 17a, 19a, 19c, 21b and 22b from soil map of Nigeria, which dominated this region were chosen for the experiment. These represent wetland and savannah areas, with well drained and poorly drained loamy sand, sandy loam or sandy loam surfaces over sandy clay loam subsurface. Surface samples were collected in each mapping unit using soil auger. Samples were well-labelled in sampling bags and used for laboratory analyses of micronutrients. The results showed that the available zinc in the surface soils was moderate with exception of high values recorded at two points within the 2a mapping unit. The boron levels were low to moderate while moderate to high contents of iron were observed. The findings also showed that harmful effects of zinc were not likely in pedons 17a4, 19a1, 19a3, 19c2, 21b1, 21b3, 21b4 and 22a4 where the Hazard Quotient (HQ) values obtained were less than 1. Other pedons in Kogi East have likely harmful effects of iron as their calculated HQ values were greater than 1.

A multi-purpose, multi-rotor drone system for long-range and high-altitude volcanic gas plume measurements

Abstract. A multi-rotor drone has been adapted for studies of volcanic gas plumes. This adaptation includes improved capacity for high-altitude and long-range, real-time SO2 concentration monitoring, long-range manual control, remotely activated bag sampling and plume speed measurement capability. The drone is capable of acting as a stable platform for various instrument configurations, including multi-component gas analysis system (MultiGAS) instruments for in situ measurements of SO2, H2S, and CO2 concentrations in the gas plume and portable differential optical absorption spectrometer (MobileDOAS) instruments for spectroscopic measurement of total SO2 emission rate, remotely controlled gas sampling in bags and sampling with gas denuders for posterior analysis on the ground of isotopic composition and halogens. The platform we present was field-tested during three campaigns in Papua New Guinea: in 2016 at Tavurvur, Bagana and Ulawun volcanoes, in 2018 at Tavurvur and Langila volcanoes and in 2019 at Tavurvur and Manam volcanoes, as well as in Mt. Etna in Italy in 2017. This paper describes the drone platform and the multiple payloads, the various measurement strategies and an algorithm to correct for different response times of MultiGAS sensors. Specifically, we emphasize the need for an adaptive flight path, together with live data transmission of a plume tracer (such as SO2 concentration) to the ground station, to ensure optimal plume interception when operating beyond the visual line of sight. We present results from a comprehensive plume characterization obtained during a field deployment at Manam volcano in May 2019. The Papua New Guinea region, and particularly Manam volcano, has not been extensively studied for volcanic gases due to its remote location, inaccessible summit region and high level of volcanic activity. We demonstrate that the combination of a multi-rotor drone with modular payloads is a versatile solution to obtain the flux and composition of volcanic plumes, even for the case of a highly active volcano with a high-altitude plume such as Manam. Drone-based measurements offer a valuable solution to volcano research and monitoring applications and provide an alternative and complementary method to ground-based and direct sampling of volcanic gases.

Use of termitarium soil as a viable source for biofertilizer and biocontrol

BackgroundEnvironmental deterioration arising from the misuse of pesticides and chemical fertilizers in agriculture has resulted in the pursuit of eco-friendly means of growing crop. Evidence has shown that biofertilizers and biocontrol can boost soil fertility and suppress soil pathogens without compromising the safety of the environment. Hence, the study investigated the use of termitarium soil as a viable source for biofertilizer and biocontrol.ResultsTwenty-seven soil samples were collected from nine different mound soil (household, farm and water bodies in a sterile sample bag). Aliquots of serially diluted samples were plated on nutrient agar, plate count agar, eosin methylene blue agar and MacConkey agar plates. Isolates were identified using standard microbiological techniques. Identified isolates were screened for plant growth-promoting properties using phosphate solubilization test, potassium solubilization test and indole acetic acid production test. Activities of the plant growth-promoting bacteria were carried out using antagonism by diffusible substance method and antagonistic activity of cell-free culture filtrate of bacterial isolates against Ralstonia solanacearum and Fusarium oxysporum. Two hundred bacterial isolates were recovered from the 27 soil samples. The most predominant isolate was Bacillus spp. Out of the 200 bacterial isolates, 57 were positive for phosphate solubilization test, potassium solubilization test and indole acetic acid production test. Out of the 57 isolates, six bacterial isolates had antagonistic activities against Fusarium oxysporum, while seven bacterial isolates antagonized Ralstonia solanacearum.ConclusionThe result showed that termite mound soil contains some useful bacteria that are capable of solubilizing phosphate and potassium and producing indole acetic acid which are the plant growth-promoting potentials and as well suppressing plant soil pathogen.

Research on Intelligent Electronic Nose Based on Exhaled Breath to Detect Halitosis

Introduction Halitosis refers to the offensive or unpleasant gas emitted from the mouth, also known as oral odor. Previous studies have shown that 80-90% of halitosis patients are caused by oral diseases[1]. The patients with thick tongue coating and periodontal disease usually have obvious halitosis and the concentrations of hydrogen sulfide and methyl mercaptan in the breath of the oral cavity were significantly higher than those of the control group. Currently there are many methods for the diagnosis of halitosis in clinic. The commonly used direct measurement techniques include organoleptic measurement, gas chromatography and portable sulfide monitor[2]. Organoleptic measurement, which involves using the human nose to score the intensity of odours emanating from the patient’s mouth, is considered the gold standard for halitosis measurement[3]. Gas chromatography is expensive and complex to operate, which requires professionals to operate. Commercial portable gas chromatography such as Oral Chroma™ (Oral Chroma™, Abimedical, Abilit Corp., Osaka, Japan) can detect the concentration of hydrogen sulfide, methyl mercaptan and dimethyl sulfide, but its price is still relatively expensive. Portable sulfide monitor such as the Halimeter (Interscan Corp., Chatsworth, LA, USA) is specially used to measure the total concentration of sulfide. But it takes a long time to measure and is only suitable for clinical application.Based on the breath of patients with halitosis, this study uses an electrochemical sensor array to construct a small and intelligent electronic nose device for detecting bad breath, which realized the rapid quantitative detection of hydrogen sulfide and methyl mercaptan, and gave the preliminary screening results of halitosis grade and oral diseases. Method Halitosis samples were collected in the dental clinic. All patients had not smoked, drank or ate spicy food before the examination. The dentist first checks the patient's oral health, and then uses organoleptic measurement to evaluate the level of Halitosis. This information will be marked on the sampling bags. Finally, 100 ml exhaled air was collected with Tedlar sampling bag.The volatile sulfur compounds in 81 samples of breath were qualitatively and quantitatively detected using GC-MS(gas chromatography and mass spectrometry) in the laboratory. ROC method was used to establish the threshold model of halitosis grade. In addition, a diagnosis model of orogenic diseases based on linear discriminant analysis, logistic regression and support vector machine was established. On the basis of the measurement result, a small intelligent electronic nose device for halitosis detection was constructed with an electrochemical sensor array, and the calibration was carried out using hydrogen sulfide and methyl mercaptan standard gases. The device can establish a connection with the mobile phone through Bluetooth. The level threshold model of halitosis and the diagnosis model of oral diseases are transplanted into the app on the mobile phone. The diagnosis results can be calculated by substituting the concentration value transmitted by the device into the model. Results and Conclusions The halitosis level threshold model and oral disease diagnosis model show that halitosis can be heard when the total concentration of methyl mercaptan and hydrogen sulfide is greater than 0.2ppm. When the total concentration is greater than 0.4ppm, the patient's halitosis is very obvious. The severity of periodontal disease (including periodontitis and gingivitis) is significantly correlated with the concentration of methyl mercaptan. When the concentration ratio of methyl mercaptan to hydrogen sulfide is greater than 1:1, patients usually have obvious periodontitis. The size of the electronic nose device based on the diagnosis model is 50 mm × 50 mm × 25 mm and the detection range of methyl mercaptan and hydrogen sulfide is 0 to 2 ppm with a detection limit of 0.05 ppm. In addition, the response time and recovery time of the sensor array are both within 15s, which greatly shortens the time compared with the common clinical detection methods. The standard gases of hydrogen sulfide and methyl mercaptan are mixed with air to simulate the breath samples with different odor levels. The gas detection process is controlled by smart phones, and the respective concentrations of hydrogen sulfide and methyl mercaptan can be calculated within 15 seconds. Taking threshold model as the evaluation standard, the accuracy of the detection results is more than 90%, which indicates that the device has the potential to become a household or portable electronic nose for halitosis detection.