Common Shape Research Articles

Occurrence, potential sources, and ecological risk assessment of microplastics in the inland river basins in Northern China

Microplastics (MPs) are the pollutants, found widely across various environmental media. However, studies on the MP pollution in urban rivers and the necessary risk assessments remain limited. In this study, the abundance and characteristics of microplastics in a typical urban river were examined to evaluate their distribution, sources, and ecological risks. It was observed that the abundance of MPs in sediments (220–2840 items·kg−1 dry weight (DW)) was much higher than that in surface water (2.9–10.3 items·L−1), indicating that the sediment is the “sink” of river MPs. Surface water and sediment were dominated by small particle size MPs (< 0.5 mm). Fiber and debris were common shapes of MPs in rivers and sediments. The microplastics in river water and sediments were primarily white and transparent, respectively. Polypropylene (PP) and polyethylene (PE) were the major polymers found.

Microplastic burden in native (Cambarus appalachiensis) and non-native (Faxonius cristavarius) crayfish along semi-rural and urban streams in southwest Virginia, USA

Our comparative assessment is the first study to investigate microplastic body burden in native (Cambarus appalachiensis) and non-native (Faxonius cristavarius) crayfish along a semi-rural and urban stream across different seasons. Crayfish, sediment, and surface water were collected, processed, and characterized using μRaman spectroscopy to compare microplastic polymer types and shapes across compartments. Average surface water concentrations were significantly higher in our urban stream compared to our semi-rural stream (17.3 ± 2.4 particles/L and 9.9 ± 1.3 particles/L, respectively; P = 0.015). Average sediment concentrations were similar between urban and semi-rural streams (140 ± 14.5 particles/kg and 139 ± 22.5 particles/kg, respectively; P = 0.957). Our findings showed a significant interactive effect of season, site, and nativity (i.e., species) regarding microplastic body burden in crayfish (P = 0.004). The smaller, non-native crayfish amassed more microplastic particles than the native crayfish (0.4–2.0 particles/g versus 0.4–0.8 particles/g, respectively). Fibers and fragments were the most common polymer shapes across compartments, with white and black being the dominant particle colors. Our study identified 13 plastic polymer types in crayfish and three in surface water and sediment; polypropylene was the most common polymer across compartments. This study provides evidence that crayfish body burden of microplastics can differ across species, seasons, and locations, highlighting the need for future studies to consider that sublethal impacts associated with microplastic body burden may vary by region and species.

Global Crisis Frame Matters for Unity: Resource Threat Hampers While Safety Threat Promotes Intergroup Cooperation

Realistic global crises trap humanity in common threats requiring intergroup unity to combat them. How do common threats shape intergroup cooperation? Previous studies have focused on the impact of threat severity on intergroup cooperation and yielded mixed results. We proposed that framing common threat based on two key aspects (resource vs. safety threats) has opposing effects on intergroup cooperation. We conducted three studies (N = 840) to test our assumptions. Across scenarios of combating wars (Study 1), reducing air pollutant emissions (Study 2), and mitigating climate change (Study 3), framing a crisis as resource threat hampered intergroup cooperation, whereas framing it as safety threat promoted intergroup cooperation. These effects were mediated by the pursuit of ingroup interests (Study 3). Our findings provide new insights into the complex effects of common threat on intergroup interactions and have practical implications for facilitating unity during global crises.

Surface Erosion Equations for Degradation Analysis of Several Common Three-Dimensional Shapes of Plastic Materials

Equations were derived for the biodegradative erosion of the surfaces of arbitrarily-sized circular and square objects, i.e., the decrease in volume caused by the catalytic activity of enzymes secreted by microorganisms attached to the object surfaces. Surface erosion is the primary mode of biodegradation for polyhydroxyalkanoate (PHA) objects resting on the ocean floor. Although the derivations were motivated by a need to assess the time-varying biodegradation and ultimate disintegration of PHA tubes and straws in the benthic environment, generality was maintained during the mathematical development such that the resulting equations are also applicable to other circular and square objects, including cylindrical rings, discs, and solid rods, and square plates, cubes, and prisms. Moreover, the equations are applicable to abiotic degradation via physical erosion, not just to biotic degradation caused by microbes. Surface erosion is expressed in terms of the ratio of the instantaneous mass to the initial mass, which is generally nonlinear with respect to time. The value of this ratio and the relative dimensions of the object establish a surface erosion function and its evolution over the lifetime of the object. Hence, the rate of degradation is not constant in the theory, but rather is prescribed by the irregular mass loss and the original geometry of the 3D object.

The accumulation of microplastics in fish freshwater in the Mun river, Thailand

Background: Microplastic pollution mainly occurs from terrestrial sources, but research on plastic contamination in aquatic environments is limited. Freshwater fish are widely consumed throughout Southeast Asia. Microplastic contamination is becoming an important issue that leads to human health risks from consumption. Objectives: The study aimed to determine the accumulation of microplastics ingested by fish in freshwater in the Mun River. Methods: Freshwater fishes in the Mun River caught by local fishermen and the most dominant species consumed in the Mun River include Paralaubuca typus, Phalacronotus bleekeri, and Morulius chrysophekaion. Twenty-four samples from each species were collected. Microplastics in these species were analysed for abundance, size, shape, color, and type of polymer. Results: The results showed that the average amounts of microplastic contamination in the gastrointestinal tracts (GIT) and gills of Morulius chrysophekadion were 17.70±8.20 pieces/fish, Phalacronotus bleekeri were 11.83±8.74 pieces/fish, and Paralaubuca typus were 10.25±7.56 pieces/fish, respectively. The average number of microplastics found in the urban area was 26.50±4.21 pieces/fish; in the agricultural area, it was 9.77±4.10 pieces/fish; in the confluence of the Mun and Chi River areas, it was 9.50±3.51 pieces/fish; and the natural area had 7.27±4.15 pieces/fish, respectively. The average size of microplastics found in fish was 878.29±904.41μm. The most common polymer type microplastic was polyethylene (PE) where the most common shape was Fiber-shaped, and the most common colour was blue. Conclusion: The study findings indicate a prevalent form of microplastic accumulation in three fish species especially among Morulius chrysophekaion. And findings show that every fish species in the urban area have the most contamination. As a result, fish GIT and gills should be removed before consumption to reduce exposure to microplastics instead of consuming them.

Retrospective evaluation and descriptive analysis of the prevalence of anatomical structures and variations in CBCT images before dental implant planning in a group Turkish population, part I.

The aim of this study is to emphasize the importance of using cone-beam computed-tomography in order to determine the anatomical structures and their variations before the treatment in patients who apply to the dentist clinic for implant treatment. In the study, CBCT images of 500 adult patients (240 female and 260 male), aged between 21 and 82 years, who applied for implant treatment due to missing teeth, were retrospectively analyzed. Anatomical structures and variations such as nasopalatine canal(NPC), canalis sinuosus(CS), antral alveolar artery(AAA), were evaluated in multiplanar reformation(MPR) sections which are axial, sagittal and coronal can be viewed in consistence with each other. The incidence of anatomical variation of CS in the right region was similar according to gender. The "Funnel" appearance of the NPC shape was found most common shape in both female and male patients (n = 89; 37.1% for females and n = 71; 27.3% for males). CBCT has become the most popular 3D imaging method in dental practice especially for planning dental implants. Understanding the relationship with important anatomical structures before implant applications is crucial in dealing with potential complications that may arise afterward. Assessing significant anatomical structures by CBCT and taking precautions against possible risks facilitate the work of dentists during and after procedures.

FORAMEN MAGNUM – A STUDY ON ITS MORPHOMETRY AMONG THE SOUTH INDIAN POPULATION

Objective: Foramen magnum is an oval opening present in the median region of the posterior cranial fossa of the occipital bone. The lower end of the medulla, meninges, spinal arteries, and spinal roots of accessory nerve pass through the foramen. Morphometry of the foramen magnum is studied for better learning of the structure, but this study helps in planning a safe surgery and exploration in the head-and-neck region. Various surgical approaches of the foramen provide access to the foramina on the base of the skull and prevent broad retraction of the neurovascular structures passing through them, so the morphometric study plays an important role in transcondylar approach. Methods: Fifty dry human skulls available in the Department of Anatomy, Amala Medical College and Hospital, and also at Jubilee Medical College and Hospital, Thrissur were studied for this research work, and results were statistically analyzed. Results: The most common shape of the foramen magnum was oval, the mean of anteroposterior diameter was greater than the mean of transverse diameter, p-value of the diameters was found to be significant, p-value of the mean of foramen magnum index was significant. Conclusion: This study will help the surgeons to effectively plan a surgery at the head and neck site

Study on Anatomical Structures of the Dromedary Udder.

The objectives of the present study were to describe specific anatomical structures of the dromedary udder. Eighty-six dromedary udders were examined, taking morphological measurements and producing injection casts using resin, gelatin, and paraffin. The udder of the dromedaries consists of four quarters. The shape of the udders and teats varies considerably between animals and is influenced by age, breeding, and lactation status. The most frequently found udder form was the globular udder (48.8%) and the most common teat form in this study was the funnel teat (44.2%). The most common teat tip shape was a smooth or a slightly rough ring teat (61.6%). Injection casts showed a complete separation of the teat canals. There is also no communication between tributary mammary complexes. Resin injections of the glandular tissue adjacent to the teat cistern showed an extensive branching into large, medium, and small milk ducts. Frozen sections of the udder revealed complete separation of the right and left mammary complex through the Sulcus intermammarius. The teat sections showed longitudinal folds from the tip of the teat to the base of the teat. A ring fold at the transition from the Ductus papillaris to the teat cistern was present. The results of this study increase the knowledge of the anatomical structures of the dromedary udder, which may be useful for breeding a selection of dairy dromedaries.

AN EVALUATION OF THE COOKING VESSELS UNEARTHED IN THE TOPAKLI HÖYÜK EXCAVATIONS (1967-1974)

Excavations were carried out in Topaklı Höyük by L. Polacco between 1967 and 1974. During these studies, pottery and teapots used in cooking from layer L to layer C were unearthed. Pots recovered from different layers stand out with their common shape features (rims protruding, having a neck, round body, flat bottom, and handle attached between the neck and body). The soot/burn marks observed on the pots support the idea that these pots were used for cooking. Topaklı Höyük pots have different capacities. Small-sized ones may be related to the number of people in the house or used for making sauce, while larger ones may be related to the number of people in the house or the cooked product (such as milk). A teapot used for cooking on the stove was also found in Topaklı Höyük. This vessel, like the pots, has a flared rim, a round body, a flat bottom, a spout, and a single strip handle attached between the rim and the body. The cooking pots found in the Topaklı Höyük settlement had been frequently used in the Kızılırmak Basin. Encountered in all settlements in the region, these pots continued to be used without any change in form over a wide period, from the 7th century BCE to the 1st century BCE. The form called the teapot is a continuation of the form known from the Hittite Imperial Period in the Kızılırmak Basin.

Efficient strain‐gradient mixed elements using shared degrees of freedom for the discretised fields

AbstractA displacement‐only finite‐element formulation of strain‐gradient models requires elements with continuous interpolation. Mixed formulations have been proposed to allow the use of more common element shape functions. These mixed formulations are based on the interpolation of two different fields, displacement and some kind of displacement gradient, with the relation between the two fields enforced using either Lagrange multipliers or penalty methods. All elements proposed in the literature for such formulations use a distinct set of degrees of freedom to discretise each field. In this work, we introduce for the first time shared degrees of freedom, that lead to a mixed formulation with a significantly better numerical performance. We describe how this novel mixed formulation can be derived, present individual elements implementing this, and discuss the significance of the results.

Microplastic contamination in marine mussels from the Atlantic coast of North Portugal and human risk of microplastic intake through mussel consumption

Microplastic (MP) pollution has become a global concern due to its potential impacts on the environment, ecosystem services and human health. The goals of the present study were to document the MP contamination in wild specimens of Mytilus galloprovincialis sampled along the Atlantic coast of the North region of Portugal continental (NW Portuguese coast), and to estimate the human risk of MP intake (HRI) through the consumption of local mussels as seafood. Mussels were collected at four sampling sites along the NW Portuguese coast (40 mussels per site), and the whole soft body of each mussel was analysed for MP content. HRI estimates were based on the mean of MP items per wet weight of mussel analysed tissue (MP/g) and consumption habits. A total of 132 MP items were recovered from mussels. MP had diverse sizes (98–2690 μm) and colours. The most common shapes were fibres (39%) and pellets (36%). Five polymers were identified in the MP: polyethylene (50%), polystyrene (15%), poly(ethylene vinyl acetate) (14%), polyamide (12%) and polypropylene (9%). From the 160 analysed mussels, 55% had MP. The mean and standard error of the mean of mussel contamination ranged from 0.206 ± 0.067 and 0.709 ± 0.095 MP/g. Compared to estimates based on MP contamination in mussels from other areas and varied consumption habits, the HRI through the consumption of mussels from the NW Portuguese coast is relatively low.

Asian clam Corbicula fluminea as potential biomonitor of microplastics and metal(oid)s in a Patagonian River

This study summarizes the concentration in dry weight (dw) of several metal(oid)s (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn), as well as the abundance and characteristics of microplastics (MP) in wet weight (ww) of the soft tissues of clam Corbicula fluminea from Chubut River (Patagonia, Argentina). The contents of essential elements were in the following decreasing order: Zn > Mn > Cu > Ni; meanwhile, non-essential elements Cd, Cr and Pb were below the detection limit (<0.5 μg/g dw). A high mean concentration of As (6.1 ± 0.3 μg/g dw) was found, surpassing the maximum allowable limit established by the Argentine Food Code for bivalve molluscs. The number of MP ranged from 0.07 to 1.27 items/ind. and from 0.2 to 2.9 items/g ww. Fibers were the most common shape, mainly transparent. The size of MP ranged from 42 to 1917 μm, accounting for 62 % of MP between 50 and 450 μm. The dominant polymer was PET based on the results of Raman spectroscopy. Based on the widespread distribution of MP in the environment and the wide range of effects on organisms, it is necessary to develop long-term monitoring programs for MP contamination in different environmental matrices. Understanding the bioaccumulation of MP in bivalves is crucial to assess the potential risk to human health through consumption and to the ecosystem. We propose that the widespread Asian clam could serve as a useful biomonitor for MP and As pollution in freshwater and estuarine environments such as the Chubut River.

Nanofluid natural convection of hot concentric cylinder in oval-shaped porous cavity at different eccentricity

PurposeThis paper aims to study the effect of concentric hot circular cylinder inside egg-cavity porous-copper nanofluid on natural convection phenomena.Design/methodology/approachThe finite element method–based Galerkin approach is applied to solve numerically the set of governing equations with appropriate boundary conditions.FindingsThe effects of different range parameters, such as Darcy number (10–3 = Da = 10–1), Rayleigh number (103 = Ra = 106), nanoparticle volume fraction (0 = ϑ = 0.06) and eccentricity (−0.3 = e = 0.1) on the fluid flow represent by stream function and heat transfer represent by temperature distribution, local and average Nusselt numbers.Research limitations/implicationsA comparison between oval shape and concentric circular concentric cylinder was investigated.Originality/valueIn the current numerical study, heat transfer by natural convection was identified inside the new design of egg-shaped cavity as a result of the presence of a circular inside it supported by a porous medium filled with a nanofluid. After reviewing previous studies and considering the importance of heat transfer by free convection inside tubes for many applications, to the best of the authors’ knowledge, the current work is the first study that deals with a study and comparison between the common shape (concentric circular tubes) and the new shape (egg-shaped cavity).

Global prevalence of microplastics in tap water systems: Abundance, characteristics, drivers and knowledge gaps

Tap water is a main route for human direct exposure to microplastics (MPs). This study recompiled baseline data from 34 countries to assess the current status and drivers of MP contamination in global tap water systems (TWS). It was shown that MPs were detected in 87 % of 1148 samples, suggesting the widespread occurrence of MPs in TWS. The detected concentrations of MPs spanned seven orders of magnitude and followed the linearized log-normal distribution (MSE = 0.035, R2 = 0.965), with cumulative concentrations at 5th, 50th and 95th percentiles of 0.028, 4.491 and 728.105 items/L, respectively. The morphological characteristics were further investigated, indicating that particles smaller than 50 μm dominated in global TWS, with fragment, polyester and transparent as the most common shape, composition and color of MPs, respectively. Subsequently, the SHapley Additive exPlanations (SHAP) algorithm was implemented to quantify the importance of variables affecting the MP abundance in global TWS, showing that the lower particle size limit was the most important variables. Subgroup analysis revealed that the concentration of MPs counted at the size limit of 1 μm was >20 times higher than that above 1 μm. Ultimately, current knowledge gaps and future research needs were elucidated.

A multivariate analysis of microplastics in soils along the headwaters of Yangtze river on the Tibetan Plateau

Microplastics (MPs) are among the most widespread anthropogenic pollutants of natural environments, while limited research has focused on the fate of MPs in soils along the Plateau rivers. In this study, we investigated MPs in soils along the source areas of the Yangtze River on the Qinghai–Tibet Plateau. The results showed mean MP abundance values of (89.4 ± 51.0) and (64.4 ± 24.5) items/kg of dry soils around the tributary and mainstream areas, respectively. Film, transparent colors, and polyethylene were common shape, color, and compositions, respectively. The correlation analysis and PCA revealed that MP abundance was related to soil heavy metals (Cr and Ni) and nutrients (TOC and TP) (p < 0.05). Structural equation modeling also revealed that population density was the dominant driving factor contributing to MPs, with a total effect coefficient of 0.45. In addition, the conditional fragmentation model further distinguished the differences in MP sources from upstream to downstream along the Jinsha River. The significant sources of MPs in the bare land and grasslands from the upper reaches of the Jinsha River included traffic, tourism, and atmospheric transport. In contrast, MP transport during farming activities mainly contributed to MPs in the agricultural soil in the lower reaches.

Life starts with plastic: High occurrence of plastic pieces in fledglings of northern fulmars

Plastic pollution threatens many organisms around the world. In particular, the northern fulmar, Fulmarus glacialis, is known to ingest high quantities of plastics. Since data are sparse in the Eurasian Arctic, we investigated plastic burdens in the stomachs of fulmar fledglings from Kongsfjorden, Svalbard. Fifteen birds were collected and only particles larger than 1 mm were extracted, characterised and analysed with Fourier Transform InfraRed spectroscopy. All birds ingested plastic. In total, 683 plastic particles were found, with an average of 46 ± 40 SD items per bird. The most common shape, colour and polymer were hard fragment, white, and polyethylene, respectively. Microplastics (< 5 mm) were slightly more represented than mesoplastics (> 5 mm). This study confirms high numbers of ingested plastics in fulmar fledglings from Svalbard and suggests that fulmar fledglings may be suitable for temporal monitoring of plastic pollution, avoiding potential biases caused by age composition or breeding state.

Technical note: Testing the connection between hillslope-scale runoff fluctuations and streamflow hydrographs at the outlet of large river basins

Abstract. A series of numerical experiments were conducted to test the connection between streamflow hydrographs at the outlet of large watersheds and the time series of hillslope-scale runoff yield. We used a distributed hydrological routing model that discretizes a large watershed (∼ 17 000 km2) into small hillslope units (∼ 0.1 km2) and applied distinct surface runoff time series to each unit that deliver the same volume of water into the river network. The numerical simulations show that distinct runoff delivery time series at the hillslope scale result in indistinguishable streamflow hydrographs at large scales. This limitation is imposed by space-time averaging of input flows into the river network that are draining the landscape. The results of the simulations presented in this paper show that, under very general conditions of streamflow routing (i.e., nonlinear variable velocities in space and time), the streamflow hydrographs at the outlet of basins with Horton–Strahler (H–S) order 5 or above (larger than 100 km2 in our setup) contain very little information about the temporal variability of runoff production at the hillslope scale and therefore the processes from which they originate. In addition, our results indicate that the rate of convergence to a common hydrograph shape at larger scales (above H–S order 5) is directly proportional to how different the input signals are to each other at the hillslope scale. We conclude that the ability of a hydrological model to replicate outlet hydrographs does not imply that a correct and meaningful description of small-scale rainfall–runoff processes has been provided. Furthermore, our results provide context for other studies that demonstrate how the physics of runoff generation cannot be inferred from output signals in commonly used hydrological models.

Online as-Built Building Information Model Update for Robotic Monitoring in Construction Sites

Today, automated techniques for the update of as-built Building Information Models (BIM) make use of offline algorithms restricting the update frequency to an extent where continuous monitoring becomes nearly impossible. To address this problem, we propose a new method for robotic monitoring that updates an as-built BIM in real-time by solving a Simultaneous Localization and Mapping (SLAM) problem where the map is represented as a collection of elements from the as-planned BIM. The suggested approach is based on the Rao-Blackwellized Particle Filter (RBPF) which enables explicit injection of prior knowledge from the building’s construction schedule, i.e., from a 4D BIM, or its elements’ spatial relations. In the methods section we describe the benefits of using an exact inverse sensor model that provides a measure for the existence probability of elements while considering the entire probabilistic existence belief map. We continue by outlining robustification techniques that include both geometrical and temporal dimensions and present how we account for common pose and shape mistakes in constructed elements. Additionally, we show that our method reduces to the standard Monte Carlo Localization (MCL) in known areas. We conclude by presenting simulation results of the proposed method and comparing it to adjacent alternatives.

Morphology of the Physiological Foramen: II. Maxillary and Mandibular Premolars

IntroductionInformation concerning the anatomy of the physiological foramen is still limited. The aim of this study was to investigate the distance between the physiological and anatomic apex, the shape and diameter of the physiological foramen in maxillary (Mx) and mandibular premolars (Mn). MethodsThe anatomy of the apex of 229 maxillary (first: MxP1; second: MxP2) and 221 mandibular premolars (first: MnP1; second: MnP2) from a mixed Swiss-German population was investigated by means of microcomputed tomography and 3-dimensional software imaging. ResultsThe following results were obtained in the presence of a main physiological foramen. 1. The distance between the physiological and anatomic foramen was 0.29-0.99 mm (MxP1), 0.21-1.03 mm (MxP2), 0.13-0.8 (MnP1), and 0.15-1.41 (MnP2). 2. The mean narrow and wide diameters of the physiological foramen were 0.19-0.33 mm (MxP1), 0.25-0.42 mm (MxP2), 0.28-0.37 (MnP1), and 0.28-0.40 (MnP2). 3. The most common physiological foramen shape was oval (66.7% MxP1, 89.7% MxP2, 91.8% MnP1, 64.4% MnP2). ConclusionConsidering the recommended preparation sizes based on a size corresponding to the friction, that is at the narrowest point in the area of the apical constriction (physiological foramen), and within the limitations of this ex vivo microcomputed tomography study, a final preparation size could be chosen when considering the pertaining morphologic considerations; yet, to a minimum ISO 30 size.

Estimation of Reliability under Conditional Stress - Strength Setup based on Weibull Distribution

The Weibull distribution has been extensively studied and applied across various fields due to its versatility in modeling a wide range of phenomena, especially in reliability engineering, survival analysis, and lifetime modeling. The concept of Rl a,b , which represents a system's reliability in a conditional stress-strength setup, was proposed by Sabre and Khorshidian (2021). In this research, the problem of estimating reliability of the component is considered when strength variable X and stress variable Y follow independent Weibull distributions with common shapes and different scale parameters under conditional stress-strength setup. The maximum likelihood estimator, asymptotic confidence interval, Bootstrap estimators, Boot-p estimators, and Bayes estimator under-squared error loss function with associated highest posterior density interval are constructed for conditional stress-strength reliability. Simulation study is conducted to estimate mean square error (MSE) of estimator of conditional stress-strength reliability. The real data analysis is also carried out.