Human exposure to microplastics contained in food has become a significant concern owing to the increasing accumulation of microplastics in the environment. In this paper, we summarize the presence ...of microplastics in food and the analytical methods used for isolation and identification of microplastics. Although a large number of studies on seafood such as fish and shellfish exist, estimating the overall human exposure to microplastics via food consumption is difficult owing to the lack of studies on other food items. Analytical methods still need to be optimized for appropriate recovery of microplastics in various food matrices, rendering a quantitative comparison of different studies challenging. In addition, microplastics could be added or removed from ingredients during processing or cooking. Thus, research on processed food is crucial to estimate the contribution of food to overall human microplastic consumption and to mitigate this exposure in the future.
A multimode silica-core fiber Raman laser was pumped directly by five wavelength-combined multimode diode lasers. The pump wavelengths were spread over a bandwidth of ~ 700 cm -1 , namely, at 976, ...969, 950, 940, and 915 nm. This is larger than the Raman peak shift of 490 cm -1 . The output power reached 31.5 W with an overall slope efficiency of 42% at the wavelength of 1018 nm when pumped with the maximum launched power of 175 W. According to simulations, the fiber was under-length and the output power could double in a longer fiber. Our results suggest that pumping with spectrally combined diode lasers is a promising approach to high-power fiber Raman lasers, even when the pump wavelengths are not optimized.
We demonstrate a fiber Raman laser directly pumped by two spectrally combined multimode diode lasers at ~950 and ~976 nm. The emission wavelength becomes 1020 nm, which corresponds to the first ...Stokes of 976 nm. The pump separation of 270 cm −1 is both much smaller than the Raman peak shift of 440 cm −1 and much larger than the Raman linewidth of around 100 cm −1 , which is unfavorable for efficient Raman conversion. Nevertheless, the addition of the pump at 950 nm triples the output power compared to pumping only at 976 nm. We reach 23 W of output power with slope efficiency of 51% and beam quality M 2 of 5.2 in a germanosilicate graded-index fiber.
Evidence of microplastics in humans has recently been demonstrated. The primary route of human exposure to microplastics is consumption of contaminated food and water. However, quantitative ...estimations of exposure to microplastics are limited, which hinders human health risk assessments. In this study, abundances of microplastics were measured in eight food types, comprising 90 products of table salts, soy sauces, fish sauces, salted seafood, seaweed, honey, beer, and beverage. Aggregate human exposure to microplastics via food consumption was assessed based on the number and mass of microplastics, using deterministic calculations and Monte Carlo simulations. The determinations revealed that average adult Koreans likely ingest 1.4 × 10−4 and 3.1 × 10−4 g of microplastics per week, respectively. These results are orders of magnitude smaller than earlier estimates of 0.1–5 g of microplastics per week that likely chose experimental outliers. Therefore, careful selection of literature data and estimation methods is needed to provide more realistic exposure estimations from microplastic counts. This study extends our understanding of MP occurrence in food and provides a more thorough estimate of aggregate microplastic exposure via food consumption.
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•Levels of MPs were determined between 0–20 p/g and 0–117 p/L in 90 food products.•Washing seaweed before consumption can significantly reduce the MPs intake.•PE, PP, and PET were the most dominant MPs detected in all food types.•Koreans are estimated to ingest 220–386 MP particles or 1.4–3.1 × 10−4 g per week.•Standardizations of calculations/parameters are required for the quality of measurements.
We report the first demonstration of Raman amplification in a fiber of a single Bessel-like higher order mode using a multimode pump source. We amplify the LP
-mode with a 559-µm
effective mode area ...at a signal wavelength of 1115 nm in a pure-silica-core step-index fiber. A maximum of 18 dB average power gain is achieved in a 9-m long gain fiber, with output pulse energy of 115 µJ. The Raman pump source comprises a pulsed 1060 nm ytterbium-doped fiber amplifier with V-value ~30, which is matched to the Raman gain fiber. The pump depletion as averaged over the signal pulses reaches 36.7%. The conversion of power from the multimode pump into the signal mode demonstrates the potential for efficient brightness enhancement with low amplification-induced signal mode purity degradation.
Let \(\mathcal{T}\) be a locally finite tree whose geometric boundary has infinitely many points. Suppose that a non-amenable group \(\G\) acts isometrically and geometrically on the tree ...\(\mathcal{T}\). In this paper, we show that if the length spectrum is Diophantine, then there exists a continuous function \(C\) on \(\mathcal{T}^2\) such that the heat kernel \(p(t,x,y)\) of \(\mathcal{T}\) satisfies $$\lim_{t\rightarrow \infty}t^{3/2}e^{\lambda_0t}p(t,x,y)=C(x,y)$$ for any \(x,y\in \mathcal{T}\). Here, \(\lambda_0\) is the bottom of the spectrum of the Laplacian on \(\mathcal{T}\).
Along with phantom pain, tinnitus, a phantom auditory perception occurring in the absence of an external acoustic stimulus, is one of the most representative phantom perceptions that develops in ...subjects with decreased peripheral sensory input. Although tinnitus is closely associated with peripheral hearing loss (HL), it remains unclear why only some individuals with HL develop tinnitus. In this study, we investigated the differences between 65 HL with tinnitus (HL‐T) and 104 HL with no tinnitus (HL‐NT) using a resting‐state electroencephalography data‐based volume entropy model of the brain network, by comparing the afferent node capacities, that quantify the contribution of each node to the spread of information, of all Brodmann areas. While the HL‐T group showed increased information flow in areas involved in Bayesian inference (the left orbitofrontal cortex, the left subgenual anterior cingulate cortex, and the left ventrolateral prefrontal cortex) and auditory memory storage (the right hippocampus/parahippocampus), the HL‐NT group showed increased afferent node capacity in hub areas of the default mode network (DMN; the right posterior cingulate cortex and the right medial temporal gyrus). These results suggest that the balance of activity between the Bayesian inferential network (updating missing auditory information by retrieving auditory memories from the hippocampus/parahippocampus) and DMN (maintaining the “silent status quo”) determines whether phantom auditory perception occurs in a brain with decreased peripheral auditory input.
Although tinnitus is closely associated with peripheral hearing loss (HL), it remains unclear why only some individuals with HL develop tinnitus. We have found that the balance of activity between the Bayesian inferential network (updating missing auditory information by retrieving auditory memories from the hippocampus/parahippocampus) and DMN (maintaining the “silent status quo”) determines whether phantom auditory perception occurs in a brain with decreased peripheral auditory input.
One of the main routes of human exposure to microplastics is food consumption; therefore, the quantitative analysis of microplastics in foods is important. Researchers have reported the occurrence of ...microplastics in different ways, necessitating the validation and standardization of analytical methods. In this study, we optimized pretreatment methods for three representative foods (i.e., salts, soy sauce, and salted pollock roe) and verified analytical methods, including material identification using Fourier-transform infrared spectroscopy, in four independent laboratories based on blind tests. We prepared custom-made cylindrical reference materials, visually identifiable under a microscope, using five plastic materials (polyethylene, polypropylene, polyethylene terephthalate, polystyrene, and polyamide-6). Each food sample was spiked with a randomized number of reference materials and sent to testing laboratories for analysis without notifying them the material type and number of reference materials. The average recovery rates of the reference materials for salt, soy sauce, and salted pollock roe were 73.2%, 76.9%, and 86.2%, respectively. Two-way analysis of variance of the experimental results demonstrated that the recoveries of the reference materials did not depend on any of the five plastic materials or the participating laboratories, indicating that the proposed methods are capable of reliably determining microplastics greater than 100 µm in selected foods.
•Method validation on microplastics in three food matrices was conducted.•Optimized methods showed recoveries of reference materials (∼100 µm) over 70%.•Recoveries were independent of experimenters or five plastic reference materials.•First reports on the occurrence of microplastics in soy sauce and salted pollock roe.
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