Environmental endotoxin measurement methods: standardization issues.

A method to measure liquid level and electrical properties based on ultra-wideband pulsed radar is developed in this paper. Current methods of material property measurement using free-space radar typically use computationally intensive frequency-domain analysis or finite time-domain methods. The method presented is modified from layer-stripping algorithms and includes several improvements over previous techniques, such as an antenna array that allows measurement in a metallic tank environment and a method of calibration that characterizes path-loss and near-field effects for accurate amplitude-distance prediction. The method presented here also estimates the material loss properties and uses accumulated power with noise compensation to predict reflected pulse power. The method extends the use of pulsed radar for liquid-level measurement in tanks to the evaluation of liquid permittivity and the estimation of liquid height in liquids consisting of multiple layers. The accuracy of the presented method is evaluated using a transmitting single antenna element, a four-element antenna array, and an eight-element antenna array for measurement in a metallic tank environment. Accuracy is improved with larger antenna arrays, but the calibration becomes more critical. The accuracy for varying layer heights and materials is investigated to demonstrate the method reliability.

Wood logs need to be measured for size when passing through customs to verify their quantity and volume. Due to the large number of wood logs needs through customs, a fast and accurate measurement method is required. The traditional log measurement methods are inefficient, have significant errors in determining the long and short diameters of the wood, and are difficult to achieve fast measurements in complex wood stacking environments. We use a Mask R-CNN instance segmentation model to detect the contour of the wood log and employ a binocular stereo camera to measure the log diameter. A rotation search algorithm centered on the wood contour is proposed to find long and short diameters and to optimal log size according to the Chinese standard. The experiments show that the Mask R-CNN we trained obtains 0.796 average precision and 0.943 IOUmask, and the recognition rate of wood log ends reaches 98.2%. The average error of the short diameter of the measurement results is 5.7 mm, the average error of the long diameter is 7.19 mm, and the average error of the diameter of the wood is 5.3 mm.

The modern policy of the Russian Federation on subsoil use on the Arctic shelf, as well as the need in the coming years to begin exploration and further operation of identified oil and gas fields in accordance with the offshore projects of the South, Arctic and Far Eastern Seas, using domestic equipment, based on universal underwater vehicles (PA) only confirms this. To develop a strategy for the creation of multifunctional equipment, it is necessary to monitor the accuracy characteristics of sensors and measurement methods in the hydrosphere. Based on the results of the studies, it is possible to conclude those preferences that will ensure the greatest effectiveness of measurements in the aquatic environment for the development of the Arctic shelf. The article considers the existing methodology of measurements at the working depths of the world’s oceans and analyses the specified efficiency of sensors, the principle of operation of which covers the use of technologies for creating and functioning in various physical fields.

Studying the relation between the residential environment and health requires valid, reliable, and cost-effective methods to collect data on residential environments. This 2002 study compared the level of agreement between measures of the presence of neighborhood businesses drawn from 2 common sources of data used for research on the built environment and health: listings of businesses from commercial databases and direct observations of city blocks by raters. Kappa statistics were calculated for 6 types of businesses-drugstores, liquor stores, bars, convenience stores, restaurants, and grocers-located on 1,663 city blocks in Chicago, Illinois. Logistic regressions estimated whether disagreement between measurement methods was systematically correlated with the socioeconomic and demographic characteristics of neighborhoods. Levels of agreement between the 2 sources were relatively high, with significant (P < 0.001) kappa statistics for each business type ranging from 0.32 to 0.70. Most business types were more likely to be reported by direct observations than in the commercial database listings. Disagreement between the 2 sources was not significantly correlated with the socioeconomic and demographic characteristics of neighborhoods. Results suggest that researchers should have reasonable confidence using whichever method (or combination of methods) is most cost-effective and theoretically appropriate for their research design.

Rotational‐speed measurement in harsh environments is an important topic. However, the high rotation results in rapid frequency variations in the signals of a sensor and changes in physical properties under extreme thermal circumstances cause significant difficulties in reading signals. To address this problem, we adopt wireless passive measurement methods to design a special characteristic signal circuit module that achieves precise measurement of rotational speed at high temperatures. The sensor and the readout system include a variable frequency source, a readout antenna, and a radio frequency demodulation circuit. Herein, a demodulation detector of the signal conversion circuit is designed and used in the envelope detection module of the single sideband demodulation method. In addition, a conversion circuit test platform for high‐temperature environment sensor signal is developed. From the testing, the output signal demodulation of the sensor was observed under a maximum temperature of 700°C with error less than 0.12%. The new sensor and measurement method do not require physical leads and achieve wireless noncontact accurate measurement of rotational speed at high temperature.

The purpose of this compilation is to present, in a central reference document, all of the individual annual reports summarizing the results of the environmental monitoring programs conducted at each of the Energy Research and Development Administration (ERDA) sites having a potential for environmental impact or which release a significant quantity of radioactivity or nonradioactive pollutants. Data on the levels of radioactivity and nonradioactive pollutants in effluents and the environs at each site are given, and effluent and environmental measurements and sampling results are evaluated in relation to the appropriate standards for environmental protection, including estimates of potential radiation exposures offsite. It is noteworthy that, in most cases, the potential offsite exposures are so low they cannot be determined by direct measurement methods but must be estimated by calculational techniques. All potential offsite exposures to members of the public from routine effluent releases in 1976 were less than 5 mrem/yr (i.e., less than one percent of the established radiation protection guidelines for exposure of the public). Additionally, the estimated collective man-rem dose potential to all members of the public within an 80 Km radius at all ERDA sites is less than .02 percent of the estimated man-rem dose due to natural and background environmental radiation.

Call centers represent one of the fastest growing industries in East Africa. However, there are health and safety hazards unique to this new industry. This field is underexplored for workers of call centers in East Africa and this study sought to establish the presence of acoustic shock syndrome, the age and sex characteristics of the staff involved and to determine correlation between duration of exposure and development of Acoustic shock syndrome. In a descriptive cross-sectional study, a total of 1351 employees, male 579 and female 772 subjects were recruited. They were screened for Acoustic shock syndrome. The age group of the subjects for this study ranged from 19-55 years. Those subjects with other medical conditions were excluded. The subjects were screened for acoustic shock syndrome using a questionnaire and the age, sex and duration of work was also sort. The total number of people with Acoustics shock syndrome were 385. This study has noted that 13% of workers at call centers develop Acoustic Shock syndrome irrespective of their duration of exposure. Males and females are affected equally. The peak groups affected are those with 3 and 5 years of work experience. Methods of noise measurement in such work environments need to be implemented so that a time weighted average can be established for protection of exposed workers.

The term primary production means the photosynthetic production of new organic matter from carbon of CO2 and hydrocarbonates by aquatic plants (Winberg 1960). Primary production is the basic source of external energy input into most aquatic ecosystems. Therefore, any attempt to estimate or model their energy balances first needs adequate evaluation of the size of primary production. The parameters of primary production per day and per whole season are a fundamental characteristic of the trophical status of a given water body and its ecological state (Margalef 1965). In fact, measurements of primary production have become a basic analysis to any serious hydrobiological investigation to obtain general characteristics of aquatic ecosystems and evaluate the degree of their anthropogenic transformation. Special attention was paid to estimating primary production in the oceans. These data are needed to calculate the carbon budget of the Earth in face of the greenhouse phenomenon. Therefore the development of efficient, rapid, and adequate methods of primary production measurement in aquatic environments was, and in some sense still remains, one of the key problems in hydrobiology.

Studies suggest that endotoxin levels in offices and homes may be associated with sick building syndrome or increased asthma severity. However, reported endotoxin levels in these studies were highly inconsistent, suggesting incompatible measurements from various laboratories. Therefore, an investigation of Limulus assay for endotoxin in house dust was undertaken. Interference with the assay was common and could produce endotoxin estimates varying by a factor of > 100, depending on the dilution used. Analysis of dose-response curves allowed detection of two types of interference: dilution-dependent and dilution-independent. Dilution-dependent interference persisted when samples were reassayed, but valid estimates could be obtained by appropriate dilution and data analysis. Valid estimates could not be obtained from assay showing dilution-independent interference. However, dilution-independent interference was frequently overcome by repeating the assay. Estimates based on a single sample dilution produced reasonable results on average when a dilution factor of 900 was used. However, the results were less precise from a single dilution (median coefficient of variation [CV] 40%) than from the complete dose-response curve (median CV 23%) and ranged from 11 to 240% of the estimates based on complete dose-response data. A comparison of extraction methods found that sonication in a phosphate-triethylamine buffer produced greater endotoxin activity than extraction in buffer with addition of saponin or sodium dodecyl sulfate. Endotoxin activity was stable for 8 to 10 weeks in dust samples stored at 4 and -20 degrees C but was not stable in extracts. The lot of Limulus amebocyte lysate reagent and method of detecting a response in the kinetic Limulus assay had significant effects on endotoxin estimates.

Water reservoirs are increasingly recognized as a significant anthropogenic source of methane (CH4) production and emissions, CH4 being the second most prevalent greenhouse gas (GHG) after CO2. The dominant emission pathway for CH4 in lacustrine environments is ebullition (bubbling). A survey of current ebullition measurement methods reveals a technology gap; the ability to measure ebullition rates and CH4 content simultaneously and affordably with high temporal and spatial resolution is not currently available. Characterizing and modeling methane ebullition in water reservoirs is key to quantifying lacustrine methane emissions and providing a basis for potential mitigation efforts. This report documents the development and assessment of a Methane Ebullition Measurement Apparatus (MEMA) designed for in-situ, autonomous, ebullition-rate and methane-concentration measurement in lacustrine environments. MEMA is designed to be affordable and easily replicable in-house by environmental research scientists with limited manufacturing resources, emphasizing low per-unit cost for maximum unit replication and spatial coverage. Documentation of the device's build materials, supplier list, physical design, and control code have all been made publicly available to aid in replication efforts.

Radiation Detection: Concepts, Methods, and Devices provides a modern overview of radiation detection devices and radiation measurement methods. The book topics have been selected on the basis of the authors’ many years of experience designing radiation detectors and teaching radiation detection and measurement in a classroom environment. This book is designed to give the reader more than a glimpse at radiation detection devices and a few packaged equations. Rather it seeks to provide an understanding that allows the reader to choose the appropriate detection technology for a particular application, to design detectors, and to competently perform radiation measurements. The authors describe assumptions used to derive frequently encountered equations used in radiation detection and measurement, thereby providing insight when and when not to apply the many approaches used in different aspects of radiation detection. Detailed in many of the chapters are specific aspects of radiation detectors, including comprehensive reviews of the historical development and current state of each topic. Such a review necessarily entails citations to many of the important discoveries, providing a resource to find quickly additional and more detailed information. This book generally has five main themes: Physics and Electrostatics needed to Design Radiation Detectors Properties and Design of Common Radiation Detectors Description and Modeling of the Different Types of Radiation Detectors Radiation Measurements and Subsequent Analysis Introductory Electronics Used for Radiation Detectors Topics covered include atomic and nuclear physics, radiation interactions, sources of radiation, and background radiation. Detector operation is addressed with chapters on radiation counting statistics, radiation source and detector effects, electrostatics for signal generation, solid-state and semiconductor physics, background radiations, and radiation counting and spectroscopy. Detectors for gamma-rays, charged-particles, and neutrons are detailed in chapters on gas-filled, scintillator, semiconductor, thermoluminescence and optically stimulated luminescence, photographic film, and a variety of other detection devices.

This paper uses DEA-based and non-DEA-based environmental performance measurement methods to develop and evaluate gas-flaring-related carbon emission performance indexes for dominant companies in the Nigerian upstream sector. The study relies on empirical data collected from the Nigerian National Petroleum Corporation’s Annual Statistical Bulletins. Indexes developed from the two methods are compared using paired two-sample t-test for means. Results documented reveal that most companies in the sector perform poorly and that, overall, the sector’s carbon performance indexes generated from both methods are poor. Moreover, performance indexes developed using the two methods are significantly different in terms of size, with DEA-based metrics being significantly greater than the non-DEA metrics. Further examination of the empirical results shows that reluctance by companies in the sector to embark on significant gas utilisations is further enhanced by the exploitable and vulnerable nature of Nigeria as a less developed country.

The Eurachem-CITAC Guide Quantifying Uncertainty in Analytical Measurement was put into practice in a public laboratory devoted to environmental analytical measurements. In doing so due regard was given to the provisions of ISO 17025 and an attempt was made to base the entire estimation of measurement uncertainty on available data from the literature or from previously performed validation studies. Most environmental analytical procedures laid down in national or international standards are the result of cooperative efforts and put into effect as part of a compromise between all parties involved, public and private, that also encompasses environmental standards and statutory limits. Central to many procedures is the focus on the measurement of environmental effects rather than on individual chemical species. In this situation it is particularly important to understand the measurement process well enough to produce a realistic uncertainty statement. Environmental analytical methods will be examined as far as necessary, but reference will also be made to analytical methods in general and to physical measurement methods where appropriate. This paper describes ways and means of quantifying uncertainty for frequently practised methods of environmental analysis. It will be shown that operationally defined measurands are no obstacle to the estimation process as described in the Eurachem/CITAC Guide if it is accepted that the dominating component of uncertainty comes from the actual practice of the method as a reproducibility standard deviation.

Measurement of exposure to environmental endotoxin is frequently performed using a Limulus amebocyte lysate (LAL) based assay. Recently, a new method has become available with similar sensitivity and potentially greater specificity using recombinant Factor C (rFC) from the horseshoe crab Carcinoscorpius rotundicauda. A preliminary study was carried out to determine the comparability of LAL and rFC in measuring endotoxins in house dust for large scale epidemiologic studies. House dust samples were collected from family rooms by vacuuming 1 m2 of the center of the room. Sixty sieved house dust samples were assayed for endotoxin by LAL (Cambrex, KQCL lysate) and rFC (Pyrogene, Cambrex) and for (1 --> 3)-beta-D-glucans by ELISA. The resistant parallel line estimation was used for data analysis of LAL and rFC. A four-parameter logistic fit with inverse prediction was used to calculate (1 --> 3)-beta-D-glucan levels of the samples. The spike recovery was 113.63% (95% CI = 101.69, 125.57%) for LAL and 99.69% (95% CI = 90.14, 109.24%) for rFC assays. The LAL assay gave higher endotoxin estimates compared with rFC. The LAL and rFC estimates were highly correlated (r = 0.86, P < 0.0001). The difference between LAL and rFC endotoxin estimates correlated with the LAL estimates (r = 0.51, P < 0.0001). However, the difference was not correlated with (1 --> 3)-beta-D-glucans. LAL and rFC gave comparable results, hence either assay can be used for studies of endotoxin exposure. The current study shows that (1 --> 3)-beta-D-glucan is not a major factor interfering with endotoxin measurements in house dust using a Cambrex KQCL LAL preparation.

Devices that acquire digital medical images using radiation (DR; Digital Radiography) are widely used in medical institutions to obtain information necessary for patient diagnosis, and the frequency of use is gradually increasing. By selecting 3 hospitals that perform more than 50 digital X-ray medical imaging tests per day, and by installing a glass dosimeter for environmental measurement on the outside of the examination room protection wall, entrance door, and patient viewing window, the leakage radiation dose was measured for one month from May 16, 2021 to June 21, 2021, then it was analyzed by converting into a 3-month cumulative dose. The cumulative dose equivalent of 1 cm in the glass dosimeter for 3 months outside the shielding wall at the entrance of the digital medical image acquisition radiation generating device examination room was 0.96 mSv, and the average value was 0.18 mSv. In addition, the cumulative 1 cm dose equivalent value of the glass dosimeter for 3 months outside the shielding wall on the control room side showed a maximum of 3.03 mSv and an average of 0.41 mSv. The glass dosimeter cumulative dose 1cm dose equivalent value was up to 8.31 mSv and averaged 2.09 mSv for 3 months outside the door of the patient waiting room of the digital medical image acquisition radiation generating device examination room. In addition, the glass dosimeter cumulative dose 1cm dose equivalent value for 3 months outside the control room door showed a maximum of 14.04 mSv and an average of 3.84 mSv. These research results are expected to be widely used in setting measurement methods and regulatory standards for environmental radiation safety management of medical radiation generators, and continuous research management at the national level is suggested.