This article presents results of electromagnetic (EM) simulation and experimental research of an original tapered slot antenna with modified topology and double-sided metallization. A comparison of ...this antenna with classical and antipodal topology is performed. Advantages and disadvantages of each of them are described. It is shown that due to the mirror symmetry planes in E- and H-planes, the proposed antenna has the highest crosspolar isolation and demonstrates electrodynamic characteristics acceptable for practice in the frequency range 0.5–6.6 GHz. Transition from an asymmetric 50-Ω coaxial line to a symmetric 100-Ω slotted line is made with the help of a balun placed in the same plane as the antenna. The latter simplifies the manufacturing process and radically reduces the longitudinal dimensions of the antenna. The research results indicate on potential application possibilities of the developed tapered slot antenna in various areas of wireless technologies.
In this paper electromagnetic field energy balance equation for linear homogeneous dispersive stationary medium is deduced in general form. No dispersive limitations on ε′, ε″, μ′, and μ″ are used. ...Thus the following question is answered: why do existing equations not provide correct values for accumulated energy and dissipated energy in dispersive media? An electromagnetic field energy balance equation for harmonic processes is obtained. This equation separates into active energy and reactive energy equations. Each of these equations contains four terms. For active energy equation the first two terms determine dissipation energy per unit volume. Each of these two terms can be expressed as a sum of three terms: the first one determines dissipation energy for unit volume without dispersion; the other two terms describe dissipation energy density due to dispersion. The third term is a Poynting vector real part change rate for frequency and coordinate, the last term—determines external source active energy density. The first two terms for reactive energy determine electromagnetic field accumulated energy density per unit volume. Each of these two terms of electromagnetic field accumulated energy density can be expressed as a sum of three terms: the first one determines accumulated energy for unit volume without dispersion; the other two terms are accumulated energy additions due to dispersion. The third term is a Poynting vector imaginary part change rate for frequency and coordinate. The last term—determines external source reactive energy density. Presented electromagnetic field energy characteristics definitions satisfy the second law of thermodynamics.
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The serum prevalence of brown (
Ursus arctos
) and Asiatic black bears (
Ursus thibethanus
) to 14 different pathogens is analyzed; seropositive bears to ten different pathogens are found. The ...serum prevalence is at the maximum for
Candida
sp., pseudorabies virus and
Dirofilaria
sp. Species-specific differences in the serum prevalence to different pathogens are observed for
Trichinella
sp. and
Toxoplasma gondii
, but seropositive individuals are observed only among brown bears. These variations can be explained by differences in the feeding behavior of the brown and Asiatic black bears and the frequency of contacts with the Amur tiger and its kills.
Per- and polyfluoroalkyl substances (PFAS), highly stable and persistent chemicals used in numerous industrial applications and consumer goods, pose an exceptionally difficult challenge for disposal. ...Three approaches are currently available for PFAS wastes: landfilling, wastewater treatment and incineration. Each disposal approach can return either the original PFAS or their degradation products back to the environment, illustrating that the PFAS problem is cyclical. Landfilling and wastewater treatment do not destroy PFAS and simply move PFAS loads between sites. Consumer products and various materials discarded in landfills leach PFAS over time, and landfill leachate is commonly sent to wastewater treatment plants. From wastewater treatment plants, PFAS are carried over to sludge and effluent. Sewage sludge can be landfilled, incinerated, or applied on agricultural fields, and PFAS from treated sludge (biosolids) can contaminate soil, water, and crops. Incineration of PFAS-containing wastes can emit harmful air pollutants, such as fluorinated greenhouse gases and products of incomplete combustion, and some PFAS may remain in the incinerator ash. Volatile PFAS are emitted into the air from landfills and wastewater treatment plants, and research is urgently needed on the potential presence of PFAS compounds in air emissions from commercially run incinerators. Monitoring of waste streams for PFAS, stopping PFAS discharges into water, soil and air and protecting the health of fence-line communities close to the waste disposal sites are essential to mitigate the impacts of PFAS pollution on human health.
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•Disposal of PFAS-containing wastes creates repeated cycles of contamination.•Consumer products and various materials discarded in landfills leach PFAS over time.•Wastewater treatment can transform PFAS and increase measurable PFAS concentration.•Incineration of PFAS wastes can release toxic air pollutants and greenhouse gases.•Monitoring and eliminating all PFAS releases into the environment are essential.
It is solved in closed form the problem of the uniform isotropic medium excitation with Heaviside step of magnetic field. There are represented calculation results of the medium field.
The extent of ongoing exposure to the general public from per- and polyfluoroalkyl substances (PFAS) in drinking water in the United States and worldwide remains uncertain. Here, we analyze publicly ...accessible data sets of PFAS occurrence in drinking water in the United States. Testing with detection limits below 1 ng/L revealed that mixtures of PFAS are nearly ubiquitous in surface water, the predominate source of drinking water for the U.S. population. We estimate that 18–80 million people in the U.S. receive tap water with 10 ng/L or greater concentration of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) combined, and over 200 million people likely receive water with a PFOA and PFOS concentration at or above 1 ng/L. Multiple U.S. states including California, Massachusetts, Michigan, New Hampshire, New Jersey, New York, and Vermont have either set or proposed limits for PFOA and PFOS that are significantly lower than the nonregulatory U.S. Environmental Protection Agency established lifetime drinking water health advisory level of 70 ng/L for the combined concentration of PFOA and PFOS. There is significant variation in PFAS occurrence within and between different U.S. states, highlighting the need for systematic monitoring of PFAS in both source and finished drinking water.
Per- and polyfluoroalkyl substances, or PFAS, gained significant public and regulatory attention due to widespread contamination and health harms associated with exposure. Ingestion of PFAS from ...contaminated food and water results in the accumulation of PFAS in the body and is considered a key route of human exposure. Here we calculate the potential contribution of PFOS from consumption of locally caught freshwater fish to serum levels. We analyzed data for over 500 composite samples of fish fillets collected across the United States from 2013 to 2015 under the U.S. EPA's monitoring programs, the National Rivers and Streams Assessment and the Great Lakes Human Health Fish Fillet Tissue Study. The two datasets indicate that an individual's consumption of freshwater fish is potentially a significant source of exposure to perfluorinated compounds. The median level of total targeted PFAS in fish fillets from rivers and streams across the United States was 9,500 ng/kg, with a median level of 11,800 ng/kg in the Great Lakes. PFOS was the largest contributor to total PFAS levels, averaging 74% of the total. The median levels of total detected PFAS in freshwater fish across the United States were 278 times higher than levels in commercially relevant fish tested by the U.S. Food and Drug Administration in 2019–2022. Exposure assessment suggests that a single serving of freshwater fish per year with the median level of PFAS as detected by the U.S. EPA monitoring programs translates into a significant increase of PFOS levels in blood serum. The exposure to chemical pollutants in freshwater fish across the United States is a case of environmental injustice that especially affects communities that depend on fishing for sustenance and for traditional cultural practices. Identifying and reducing sources of PFAS exposure is an urgent public health priority.
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•PFAS are widely detected in freshwater fish across the United States.•U.S. EPA fish testing in 2013–2015 had a median PFAS concentration of 11,800 ng/kg.•Even infrequent freshwater fish consumption can increase serum PFOS levels.•One fish serving can be equivalent to drinking water for a month at 48 ppt PFOS.•Fish consumption advice regarding PFAS is inconsistent or absent in the U.S. states.
Nitrate ingestion from drinking water has been associated with an increased risk of adverse birth outcomes as well as elevated risk of colorectal cancer and several other cancers. Yet, to date, no ...studies have attempted to quantify the health and economic impacts due to nitrate in drinking water in the United States.
This study presents a first-of-its-kind comprehensive assessment of nitrate exposure from drinking water for the entire United States population. This exposure assessment serves as the basis for our analysis of the annual nitrate-attributable disease cases in the United States and the associated economic losses due to medical costs and lost productivity. Additionally, through a meta-analysis of studies on drinking water nitrate and colorectal cancer, we examine the exposure-response relationship for nitrate and cancer risk.
On the basis of national nitrate occurrence data and relative risk ratios reported in the epidemiology literature, we calculated that annually, 2939 cases of very low birth weight, 1725 cases of very preterm birth, and 41 cases of neural tube defects could be related to nitrate exposure from drinking water. For cancer risk, combining nitrate-specific risk estimates for colorectal, ovarian, thyroid, kidney, and bladder cancers results in a range of 2300 to 12,594 annual nitrate-attributable cancer cases (mean: 6537 estimated cases). For medical expenditures alone, this burden of cancer corresponds to an annual economic cost of 250 million to 1.5 billion U.S. dollars, together with a potential 1.3 to 6.5 billion dollar impact due to lost productivity. With the meta-analysis of eight studies of drinking water nitrate and colorectal cancer, we observed a statistically significant positive association for nitrate exposure and colorectal cancer risk and calculated a one-in-one million cancer risk level of 0.14 mg/L nitrate in drinking water.
Health and economic analyses presented here suggest that lowering exposure to nitrate in drinking water could bring economic benefits by alleviating the impacts of nitrate-associated diseases.
•First of its kind national analysis assessing nitrate exposure from drinking water for the entire U.S. population.•2,300 to 12,594 nitrate-attributable cancer cases annually in the U.S., of which 54-82% are colorectal cancer (CRC) cases.•Up to $1.5 and $6.5 billion in medical and indirect costs may be associated with annual nitrate-attributable cancer cases.•Meta-analysis of eight studies assessing nitrate in drinking water and CRC supports a health benchmark of 0.14 mg/L.
Abstract
Background
Epidemiological studies and research on laboratory animals link radiofrequency radiation (RFR) with impacts on the heart, brain, and other organs. Data from the large-scale animal ...studies conducted by the U.S. National Toxicology Program (NTP) and the Ramazzini Institute support the need for updated health-based guidelines for general population RFR exposure.
Objectives
The development of RFR exposure limits expressed in whole-body Specific Absorption Rate (SAR), a metric of RFR energy absorbed by biological tissues.
Methods
Using frequentist and Bayesian averaging modeling of non-neoplastic lesion incidence data from the NTP study, we calculated the benchmark doses (BMD) that elicited a 10% response above background (BMD
10
) and the lower confidence limits on the BMD at 10% extra risk (BMDL
10
). Incidence data for individual neoplasms and combined tumor incidence were modeled for 5% and 10% response above background.
Results
Cardiomyopathy and increased risk of neoplasms in male rats were the most sensitive health outcomes following RFR exposures at 900 MHz frequency with Code Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM) modulations. BMDL
10
for all sites cardiomyopathy in male rats following 19 weeks of exposure, calculated with Bayesian model averaging, corresponded to 0.27–0.42 W/kg whole-body SAR for CDMA and 0.20–0.29 W/kg for GSM modulation. BMDL
10
for right ventricle cardiomyopathy in female rats following 2 years of exposure corresponded to 2.7–5.16 W/kg whole-body SAR for CDMA and 1.91–2.18 W/kg for GSM modulation. For multi-site tumor modeling using the multistage cancer model with a 5% extra risk, BMDL
5
in male rats corresponded to 0.31 W/kg for CDMA and 0.21 W/kg for GSM modulation.
Conclusion
BMDL
10
range of 0.2—0.4 W/kg for all sites cardiomyopathy in male rats was selected as a point of departure. Applying two ten-fold safety factors for interspecies and intraspecies variability, we derived a whole-body SAR limit of 2 to 4 mW/kg, an exposure level that is 20–40-fold lower than the legally permissible level of 0.08 W/kg for whole-body SAR under the current U.S. regulations. Use of an additional ten-fold children’s health safety factor points to a whole-body SAR limit of 0.2–0.4 mW/kg for young children.
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