Plastic Mass Research Articles

Theoretical Study and Experiment Validation on Drilling Cutting Weight during the Whole Process of Drilling

In mining engineering, coal and gas outburst is extremely dangerous dynamic disaster, which will cause serious casualties and property losses. As a method to predict coal burst, the drilling cutting method has been widely used in coal mines. The drilling cutting weight is an important index of the drilling cutting method. In theoretical calculation, scholars usually assume that the coal is isotropic and homogeneous before drilling to deduce the formula of drilling cutting weight. However, in actual mining engineering, drilling cutting is usually carried out in the plastic coal body in front of the working face. Therefore, in the present study, the theoretical formula of the drilling cutting weight in the plastic coal mass is deduced, as well as in the elastic coal mass. The results show that the drilling cutting weight calculated based on the deduced formula increases with the increase of drilling depth in the plastic coal mass, which is consistent with the field measurement results. The fragmentation degrees of coal around the drilling hole are also considered by introducing cohesion, which changes linearly along the radial direction of the drilling hole. The results show that the smaller the cohesion, the greater the drilling cutting weight. The calculation formula for drilling cutting in elastic coal mass is also given. The dilatancy effect of coal around the drilling hole is also considered by introducing expansion coefficient n, which changes linearly along the radial direction of the drilling hole. There is a good match between the theoretical calculation results and the laboratory test results. The obtained results are helpful for the prediction and prevention of coal burst.

Tradition and innovation in polymer chemistry and technology

The main directions of scientific research on the chemistry and technology of plastic masses performed at the St.Petersburg State Institute of Technology (Technical University) are defined. The article is dedicated to the 100th anniversary of the birth of Professor Anatoly Fedorovich Nikolaev.

Application of hard coal combustion residuals in the production of ceramic building materials

The combustion of solid fuels results in solid by-products, i.e. slags and ashes. This waste is a potential source of many valuable mineral materials that should be used to the maximum extent. The amount of solid waste generated in combustion processes depends on the quality of coal and its natural ash content. In addition, the amount of waste is increased by a portion of unburnt coal depending on the furnace efficiency. The paper presents the results of research on the application of combustion waste as an additive to the ceramic mass used in the production of ceramic clinker products. Two furnace slags differing in origin were used in the investigations. Their physicochemical characteristics and the effect of this waste on the properties of clinker ceramics were determined. The required test specimens were formed from plastic ceramic masses containing wt. 30% of the waste. After firing at temperatures ranging from 1100 to 1200 °C, the linear shrinkage, water absorption, open porosity, apparent density and compressive strength of the obtained materials were determined. The results of the conducted research indicate that combustion waste can be considered as a valuable secondary raw material for the production of ceramic clinker products, because it intensifies the sintering process of clinker ceramics.

Investigation of the method of dehydration of organomineral fertilizer based on liquid waste of pig farms

The article deals with the research of possible methods of dehydration of organomineral fertilizers based on liquid waste of pig farms. Technologies and various methods of sludge dewatering after reagent treatment of liquid waste from pig farms and related processes are analyzed. Based on the results of the analysis, a comprehensive scheme is proposed that can meet the needs of processing waste from large pig farms and provide farmers with a sufficient amount of available fertilizers. The dependences of the dynamics of moisture removal and dewatering on the devices used are obtained. It is established that the productivity of aggregate operations for the removal of excess liquid at the first stage and dehydration of organomineral fertilizers can be expressed in qualitative indicators — different structure of the final product-organomineral fertilizer in the form of powder, granules or plastic mass. The interaction between individual operations in the technological chain is considered, the technical indicators of various scenarios of dehydration of organomineral fertilizers are analyzed.

Temporal trends and interannual variation in plastic ingestion by Flesh-footed Shearwaters (Ardenna carneipes) using different sampling strategies

The world's oceans are under increasing pressure from anthropogenic activities, including significant and rapidly increasing inputs of plastic pollution. Seabirds have long been considered sentinels of ocean health, providing data on physical and chemical pollutants in their marine habitats. However, long-term data that can elucidate important patterns and changes in seabird exposure to marine pollutants are relatively limited but are urgently needed to identify and support effective policy measures to reduce plastic waste. Using up to 12 years of data, we examined the benefits and challenges of different approaches to monitoring plastic in seabirds, and the relationship between plastic and body size parameters. We found the mass and number of ingested plastics per bird varied by sample type, with lavage and road-kill birds containing less plastic (9.17–9.33 pieces/bird) than beach-washed or otherwise dead birds (27.62–32.22 pieces/bird). Beached birds therefore provide data for only a particular subset of the population, mostly individuals in poorer body condition, including those severely impacted by plastics. In addition, the mass and number of plastics in beached birds were more variable, therefore the sample sizes required to detect a change in plastic over time were significantly larger than for lavaged birds. The use of lavaged birds is rare in studies of plastic ingestion due to ethical and methodological implications, and we recommend future work on ingested plastics should focus on sampling this group to ensure data are more representative of a population's overall exposure to plastics.

Plastic transport in a complex confluence of the Mekong River in Cambodia

Field data on plastic pollution is extremely limited in Southeast Asian rivers. Here we present the first field measurements of plastic transport in the Mekong, based on a comprehensive monitoring campaign during the monsoon season in the confluence of the Mekong, Tonle Sap, and Bassac rivers around Cambodia’s capital (Phnom Penh). For improved accuracy in the estimation of plastic loads and distribution, we combined Neuston net multipoint cross-sectional water sampling with acoustic Doppler current profiler high resolution measurements. During the wet season, around 2.03 × 105 kg d−1 of plastic were released from Phnom Penh into the Mekong, equivalent to 89 g d−1 capita−1, or 42% of all plastic waste generated in the city. Most plastic mass moved downstream at the surface. A smaller portion of plastics is mixed deep into the water column, potentially retained in the rivers, breaking down and resuspending over time. Overall, plastic waste from Phnom Penh and transported by the Mekong is a significant contribution to Southeast Asia’s plastic release into the ocean. This pollution represents a crucial risk to people in the region, as their livelihoods depend on fisheries from these water bodies.

Characterization of Ferromagnetic Composite Implants for Tumor Bed Hyperthermia

Hyperthermia therapy (HT) is becoming a well-recognized method for the treatment of cancer when combined with radiation or chemotherapy. There are many ways to heat a tumor and the optimum approach depends on the treatment site. This study investigates a composite ferromagnetic surgical implant inserted in a tumor bed for the delivery of local HT. Heating of the implant is achieved by inductively coupling energy from an external magnetic field of sub-megahertz frequency. Implants are formed by mechanically filling a resected tumor bed with self-polymerizing plastic mass mixed with small ferromagnetic thermoseeds. Model implants were manufactured and then heated in a 35 cm diameter induction coil of our own design. Experimental results showed that implants were easily heated to temperatures that allow either traditional HT (39-45°C) or thermal ablation therapy (>50°C) in an external magnetic field with a frequency of 90 kHz and amplitude not exceeding 4 kA/m. These results agreed well with a numerical solution of combined electromagnetic and heat transfer equations solved using the finite element method.

Ocean Plastic Assimilator v0.2: assimilation of plastic concentration data into Lagrangian dispersion models

Abstract. A numerical scheme to perform data assimilation of concentration measurements in Lagrangian models is presented, along with its first implementation called Ocean Plastic Assimilator, which aims to improve predictions of the distributions of plastics over the oceans. This scheme uses an ensemble method over a set of particle dispersion simulations. At each step, concentration observations are assimilated across the ensemble members by switching back and forth between Eulerian and Lagrangian representations. We design two experiments to assess the scheme efficacy and efficiency when assimilating simulated data in a simple double-gyre model. Analysis convergence is observed with higher accuracy when lowering observation variance or using a circulation model closer to the real circulation. Results show that the distribution of the mass of plastics in an area can effectively be improved with this simple assimilation scheme. Direct application to a real ocean dispersion model of the Great Pacific Garbage Patch is presented with simulated observations, which gives similarly encouraging results. Thus, this method is considered a suitable candidate for creating a tool to assimilate plastic concentration observations in real-world applications to estimate and forecast plastic distributions in the oceans. Finally, several improvements that could further enhance the method efficiency are identified.

Taking a mass-balance approach to assess marine plastics in the South China Sea

The South China Sea (SCS) is recognised as a global hotspot for plastic pollution. We review available field studies and identify a significant lack of data needed to construct a simple mass balance box model for plastic pollution in the SCS. Fundamental information on plastic mass input, transfer and sink terms are simply not available. Also unknown are the rates of accumulation in different environments, the dispersal pathways of plastic particles of different density, the residence times of plastic in the water column and the rate at which macroplastics are transformed into microplastics in different environments. Filling these information gaps is critical for states to determine adequate response measures, including developing and tracking impact of policies to deal with the problem of plastic pollution in the SCS.

Demographic Differences in the Quantity, Mass, and Anatomical Location of Ingested Plastic in Northern Fulmars (Fulmarus glacialis): A Review and Reconsideration of NE Pacific Ocean Samples

On the Washington and Oregon coast of the NE Pacific Ocean from 2008-2015, we found that juveniles represented 83% of Northern Fulmars that were beached. In comparison to older birds, juveniles averaged more mass and pieces of plastic in stomachs. This reflected relatively larger plastic loads in the cranial stomach section, the proventriculus, which we found was associated with relatively large accumulations in the caudal stomach section, the ventriculus. We estimate that the proventriculus could retain almost 10 times as much plastic as the ventriculus and that retention of proventricular plastic largely accounted for the difference in juveniles versus older birds. Our findings contrast with published Atlantic Ocean reports where the proportion of immatures was lower and plastic was retained mostly in ventriculi. The differences in demography and gastric distribution between NE Pacific and Atlantic fulmars may reflect the different sizes of plastic particles that were available. The preponderance of juveniles in NE Pacific Ocean samples and associated relatively large plastic loads overestimate the load for the species. Without accounting for age and gastric distribution, comparison to other regions is ill-advised. An unrecognized complication in stomach-based sampling is that differences in size of plastic at spatiotemporal scales could affect the utility of stomach samples as bioindicators of oceanic plastic pollution.

The missing ocean plastic sink: Gone with the rivers.

Plastic floating at the ocean surface, estimated at tens to hundreds of thousands of metric tons, represents only a small fraction of the estimated several million metric tons annually discharged by rivers. Such an imbalance promoted the search for a missing plastic sink that could explain the rapid removal of river-sourced plastics from the ocean surface. On the basis of an in-depth statistical reanalysis of updated data on microplastics-a size fraction for which both ocean and river sampling rely on equal techniques-we demonstrate that current river flux assessments are overestimated by two to three orders of magnitude. Accordingly, the average residence time of microplastics at the ocean surface rises from a few days to several years, strongly reducing the theoretical need for a missing sink.

No missing sink

Plastic Pollution Estimates of the flux of microplastics from rivers, in the context of the mass of plastic that has been observed in the ocean, have made it appear that a large, unidentified sink of plastics must exist there. Weiss et al. show that there may not be a missing sink after all. By reformulating how mass fluxes are calculated from observations of particle numbers, they demonstrate that those mass fluxes were overestimated by two to three orders of magnitude. This explains why the residence time of plastics in the ocean seemed so puzzlingly short and implies that ocean plastics may persist and degrade over longer periods than previously thought. Science , abe0290, this issue p. [107][1] [1]: /lookup/doi/10.1126/science.abe0290

Innovative solutions to increase productivity, safety and reliability of agricultural products processing equipment

It is noted that the agro-industrial complex is a stable supplier of food for the population and raw materials for various types of economic activities. In addition, works related to sawing of various solid materials (wood, plastic masses, frozen meat and fish products, bones and others are characteristic. The equipment used in this case is characterized by metal capacity, insufficient productivity and low reliability, increased injury hazard. In addition, wood sawing equipment is expensive and high-energy. In connection with the present, based on the study and analysis of the situation, the authors proposed an author's solution that allows reducing the shortcomings of existing equipment by half, providing an increase in productivity, reliability and safety in operation. This is facilitated by innovative design solutions, providing, in particular, sawing of materials when the saw block moves not only downwards, but also upwards according to the principle of a crank mechanism. The following material is devoted to the presentation of the design and principle of the proposed innovative solution.

A complete mass balance for plastics in a wastewater treatment plant - Macroplastics contributes more than microplastics

A complete plastic particle mass balance was established at Sweden's second-largest wastewater treatment plant. It comprised material collected at its two bar screens, a 20 mm and a 2 mm one, in the influent water after the 20 mm screen, the effluent water, and the digested sludge. Macro- and microplastics above 500 µm were analysed individually applying ATR-FTIR, while microplastics of 10–500 µm were analysed by µFTIR imaging with automated particle recognition. Masses of plastics >500 µm were determined by weighting, while the mass of the smaller microplastics was estimated from the imaging. The total plastic load on the plant was 202.2 kg d−1, of which the two screens retained 73%. The remaining plastic mass was found in the sludge (13.6%) and the effluent (0.4%). The missing 12.7% could be caused by sampling and measuring uncertainties and potentially also fragmentation below the size detection limit of the analytical approach, or by degradation. The bar screens furthermore retained plastics smaller than the screen size, indicating that this material should be taken into account also when solely looking at smaller particles. The overall treatment efficiency of the plant was high: 99.6% considering both macro- and microplastics, and 98.8% considering only microplastics <500 µm.

Plastic debris increases circadian temperature extremes in beach sediments

Plastic pollution is the focus of substantial scientific and public interest, leading many to believe the issue is well documented and managed, with effective mitigation in place. However, many aspects are poorly understood, including fundamental questions relating to the scope and severity of impacts (e.g., demographic consequences at the population level). Plastics accumulate in significant quantities on beaches globally, yet the consequences for these terrestrial environments are largely unknown. Using real world, in situ measurements of circadian thermal fluctuations of beach sediment on Henderson Island and Cocos (Keeling) Islands, we demonstrate that plastics increase circadian temperature extremes. Particular plastic levels were associated with increases in daily maximum temperatures of 2.45°C and decreases of daily minimum by − 1.50°C at 5 cm depth below the accumulated plastic. Mass of surface plastic was high on both islands (Henderson: 571 ± 197 g/m2; Cocos: 3164 ± 1989 g/m2), but did not affect thermal conductivity, specific heat capacity, thermal diffusivity, or moisture content of beach sediments. Therefore, we suggest plastic effects sediment temperatures by altering thermal inputs and outputs (e.g., infrared radiation absorption). The resulting circadian temperature fluctuations have potentially significant implications for terrestrial ectotherms, many of which have narrow thermal tolerance limits and are functionally important in beach habitats.

Modelling size distributions of marine plastics under the influence of continuous cascading fragmentation

Field studies in the global ocean have shown that plastic fragments make up the majority of plastic pollution in terms of abundance. It is not well understood how quickly plastics in the marine environmental fragment, however. Here, we study the fragmentation process in the oceanic environment by considering a model which captures continuous fragmentation of particles over time in a cascading fashion. With this cascading fragmentation model we simulate particle size distributions (PSDs), specifying the abundance or mass of particles for different size classes. The fragmentation model is coupled to an environmental box model, simulating the distributions of plastic particles in the ocean, coastal waters, and on the beach. We demonstrate the capabilities of the model by calibrating it to estimated plastic transport in the Mediterranean Sea, and compare the modelled PSDs to available observations in this region. Results are used to illustrate the effect of size-selective processes such as vertical mixing in the water column and resuspension of particles from the beach into coastal waters. The model quantifies the role of fragmentation on the marine plastic mass budget: while fragmentation is a major source of secondary plastic particles in terms of abundance, it seems to have a minor effect on the total mass of particles larger than 0.1 mm. Future comparison to observed PSD data allow us to understand size-selective plastic transport in the environment, and potentially inform us on plastic longevity.

Plastics in regurgitated Flesh-footed Shearwater (Ardenna carneipes) boluses as a monitoring tool

Plastic production and pollution of the environment with plastic items is rising rapidly and outpacing current mitigation measures. Success of mitigation actions can only be determined if progress can be measured reliably through incorporation of specific, measurable targets. Here we evaluate temporal changes in the amount and composition of plastic in boluses from Flesh-footed Shearwaters during 2002–2020 and assess their suitability for measuring progress against national and international commitments to reduce plastic pollution. Plastic in the shearwater boluses showed a generally decreasing pattern from 2002 to 2015 and increasing again to 2020. The colour and type of plastics in boluses was comparable to items recovered from live and necropsied birds, but a much smaller sample size (~35 boluses/year) was required to detect changes in plastic number and mass over time. We therefore suggest shearwater boluses are a low-effort, high-statistical power monitoring tool for quantifying progress against environmental policies in Australia.

Study of implants for intraoperative hyperthermia

At the present time hyperthermia is recognized as one of the most promising methods in the combined treatment of malignant tumors. Nevertheless, for the most of existing methods for heating of tumor tissues it is rather difficult to realize the exact localization of heat exposure. The aim of this study is to compare two types of implants for intraoperative local tumor bed hyperthermia carried out using induction heating in an alternating magnetic field of the sub-MHz range. Composite implants of the first type are created on the base of a self-curing plastic mass mixed with electrically conductive ferromagnetic particles. The second type of implant is a hollow object with thin walls that follows the shape of the tumor. Implants of this type are filled with a liquid metal non-magnetic alloy with melting point below room temperature. The model implants were heated in a self-designed inductor with a short cylindrical coil 35 cm in diameter. Biological tissues were modeled using an ultrasound gel. Experimental results show that both types of implants were heated in an external alternating magnetic field with a frequency of 90 kHz and an amplitude not exceeding 4 kA/m up to temperatures that allow both traditional hyperthermia (tissue heating to 41-45 °C) and thermal ablation therapy (tissue heating to temperatures above 50 °C). Good agreement between the experimental data and model numerical calculations was obtained.

Assessing plastic size distribution and quantity on a remote island in the South Pacific

Plastics are an environmental threat; however, their fate once in the pelagic environment is poorly known. We compare results from assessments of floating plastics in the South Pacific Ocean with accumulated beach plastics from Henderson Island. We also compare accumulated plastic mass on Henderson during 2015 and 2019 and investigate the presence of nanoplastics. There were differences between the size classes of beach and pelagic plastics, and an increase in microplastics (0.33–5 mm) on the beach between 2015 and 2019. Micro- and nanoplastics were found at all sites (mean ± SE: 1960 ± 356 pieces/kg dw). Across the whole beach this translates to >4 billion plastic particles in the upper 5 cm. This is concerning, particularly given Henderson is uninhabited and distant from urban centres (~2350 km from Pape'ete, French Polynesia). The vast number of small particles on Henderson may make nearshore filter feeders susceptible to ingestion and subsequent detrimental impacts.

New tools to evaluate plastic ingestion by northern fulmars applied to North Sea monitoring data 2002–2018

Monitoring plastic in stomachs of beached northern fulmars for OSPAR's Ecological Quality Objectives (EcoQOs) has been incorporated into the European Marine Strategy Framework Directive (MSFD). This paper aims to provide the appropriate tools to interpret the monitoring results. MSFD requires a data-derived threshold value (Fulmar-TV) representing ‘Good Environmental Status’. Such Fulmar-TV was calculated from near-pristine Canadian Arctic data where 10.06% of fulmars exceeded the level of 0.1 g ingested plastic. This Fulmar-TV is almost identical to the earlier OSPAR EcoQO, arbitrarily set at 10%. The MSFD approach was evaluated for 2661 North Sea fulmars in 2002–2018. Between 2014 and 2018, 51% of 393 fulmars exceeded 0.1 g plastic, significantly above the proposed Fulmar-TV. Linear regression of individual ingested plastic mass over the 2009–2018 period indicates a significant decrease. Over the longer term 2002–2018, logistic regression of annual EcoQ% shows a significant decline and predicts compliance with the Fulmar-TV by 2054.