Plastic Volume Research Articles

Decision-science navigates trade-offs between environmental and socio-economic objectives for marine debris mitigation

Context Marine litter is a growing global problem that impacts biodiversity and human societies alike. South-east Asia suffers significant impacts due to high biodiversity, dense human populations, and large volumes of plastics entering the marine environment, primarily through rivers. Aims Drawing on decision-theory principles, Structured Decision Making (SDM) can improve site selection for marine debris management by identifying the best options to reduce plastic exposure to species, ecosystems, and human populations in the marine and coastal environment, as well as an overall reduction of drifting plastic debris in the open ocean. Methods We combine an SDM framework with a plastic transport model and quantify benefits for environmental and social objectives across 542 locations covering 683 rivers along the coasts of south-east Asia in the biodiversity hotspot of the Coral Triangle. We modelled and quantified metrics for the reduction in volume and flow of plastics to all downstream coral reefs, key biodiversity areas, marine protected areas, and coastal communities. Key results No location is the best option across all objectives, but the multiple metrics help to navigate trade-offs across specific objectives. Despite 95% of all plastic debris remaining in circulation in the seascape after 2 months, several rivers contribute not only large volumes of plastic debris to the overall marine pollution but also large volumes of pollution downstream. Conclusions The increasing pollution of the marine environment with plastic debris can only be stopped by regulating and reducing the production of plastic products. However, as long as plastic debris is still circulating in the environment, the identification of these locations where the removal of plastic pollution will deliver the best outcomes for a set of important objectives will remain an important mitigation measure. The proposed framework effectively facilitates understanding existing trade-offs and can easily be adapted to include additional metrics or objectives. Using this framework enables decision-makers to develop a tailor-made prioritisation process for clean-up interventions in their unique socio-ecological contexts. Implications This new decision-science approach for identifying efficient spatial management strategies for plastic clean-up is transferable to any geography and has the capacity to enhance local-to-global plastic management.

Defining a Danger Zone for Iatrogenic Long Thoracic Nerve Injury in Gender-Affirming Mastectomy

The long thoracic nerve's (LTN) superficial location on the chest wall renders it vulnerable to iatrogenic injury. Plastic surgeons' gender-affirming mastectomy volumes are rapidly increasing. This operation involves lateral chest contouring placing the distal LTN at risk of injury along the chest wall. Although proximal LTN injury can cause debilitating shoulder dysfunction, more distal injury can cause chronic postoperative shoulder pain and dysfunction without frank scapular winging, making diagnosis and treatment difficult. Therefore, injury is best avoided. In this study, the course of the LTN relative to the lateral border of the pectoralis major muscle was mapped to delineate and define a danger zone for LTN injury in gender-affirming mastectomy. The course of the LTN along the lateral chest wall relative to the pectoralis major lateral border was prospectively mapped using intraoperative nerve stimulation. Twelve individuals were enrolled. The LTN was mapped bilaterally and was most reliably located directly lateral to the intersection of the 4th rib and the lateral border of the pectoralis major muscle. The LTN was found a median of 4.3cm (interquartile range [IQR] = 0.9cm) lateral to the pectoralis major at the 3rd rib level, 5.0cm (IQR = 0.5cm) lateral to the pectoralis border at the 4th rib level, and 7.0cm (IQR = 0.5cm) lateral to the pectoralis border at the 5th rib level. In conclusion, this study defines a danger zone for LTN injury in gender-affirming mastectomy. With recent increases in the number of plastic surgeons performing gender-affirming mastectomies, awareness of this LTN danger zone is important to avoid iatrogenic injuries.

Does simplification of plastic waste separation promote plastic recycling?

This study explores the effects of a policy intervention designed to simplify the standards for plastic waste separation on collection volume and the quality of recyclables. We employ a causal impact analysis based on a Bayesian structural time-series approach to estimate the effects of simplifying the municipal solid waste-separation process for plastic waste in Japan. We find that simplifying plastic waste-separation standards increases plastic packaging waste-collection volume. This effect seems to be largely driven by behavioral changes such as decreased time spent on waste separation. We also find that simplifying home separation increases the percentage of contaminated plastic packaging waste collected for recycling and other materials not subject to collection in the post-collection period. Several robustness and falsification tests corroborated these results. Our results highlight the importance of considering the trade-off between the quantity and quality of recyclables when designing plastic waste recycling policies.

Degradation of Decabromodiphenyl Ether Dispersed in Poly (Acrylo-Butadiene-Styrene) Using a Rotatory Laboratory Pilot Under UV-Visible Irradiation.

The growing volume of plastics derived from electronic waste (e-waste) underscores the imperative for environmentally sustainable strategies for the management of this waste. In light of the paramount importance of this issue, a pilot demonstrator for the decontamination of polymers containing Brominated Flame Retardants (BFRs) has been developed. The objective is to investigate the potential for decontaminating BFR-containing polymers from e-waste via UV-visible irradiation using a rotatory laboratory pilot operating under primary vacuum conditions. This report focuses on binary model blends composed of 90 weight% (wt%) poly(Acrylo-Butadiene-Styrene) (ABS) pellets and 10 wt% Deca-Bromo-Diphenyl Ether (DBDE), which is one of the most toxic BFRs. The efficiency of the irradiation process was evaluated as a function of pellet diameter and irradiation time using Fourier Transform InfraRed spectroscopy (FTIR) and High-Resolution Laser Desorption/Ionization Mass Spectroscopy (HR-LDI-MS). As a consequence, ABS + DBDE achieved a decontamination efficiency of 97% when irradiated with pellets of less than 1 mm in diameter for a period of 4 h. Additionally, the thermal behavior of the irradiated samples was investigated through thermogravimetric analysis and differential scanning calorimetry. It was thus established that the application of UV-visible irradiation had no significant impact on the overall thermal properties of ABS.

Impact of Public Health and Social Measures on Cosmetic Treatments in the COVID-19 Pandemic: A Retrospective Multi-Center Study Combined With a Questionnaire-Based Cross-Sectional Study.

Public health and social measures (PHSMs) are considered the most effective approaches for controlling epidemic diseases. This study aimed to explore variations in the time-dependent characteristics of and public preferences for cosmetic treatments during and after the implementation of PHSMs during the COVID-19 pandemic. Medical records from six medical institutions were extracted retrospectively. Time-series analyses were conducted to reveal the variations in characteristics in volume and proportion of cosmetic treatments according to PHSMs. A cross-sectional study was conducted with online questionnaire designed for the general population during and after the implementation of PHSMs. A total of 141 033 records were included in this retrospective study. The implementation of PHSMs led to extremely low treatment volumes; compared with the increases in private hospitals, the treatment volumes in public hospitals exhibited earlier and more significant increases, even higher than pre-PHSM levels (p < 0.05), which mainly contributed to the increase in plastic surgery volumes during and after the implementation of PHSMs. The differences in the anxiety state, self-perceived appearance, and cosmetic treatment intentions of the participants were illustrated during and after PHSMs. We further demonstrated the participants' decisions on cosmetic treatments after the implementation of PHSMs during the COVID-19 pandemic. The immediate effects and aftereffects of PHSMs on cosmetic treatments were different in public and private hospitals. Furthermore, as PHSMs guided the adjustment of cosmetic treatments in the post-COVID-19 era, the intention to undergo cosmetic treatment during PHSMs was associated with the anxiety states and preferences of the population.

Influence of Geographic Separation Between Urban Centers and Microplastic Burden on Bees (Apis mellifera)

Plastic, a product of industrialization, has become an integral part of human life since its inception. Its extensive usage has led to a drastic increase in production, resulting in the widespread accumulation of plastic waste at various levels. Improper disposal practices have compounded this issue, transforming plastic waste into a significant environmental concern. Factors such as the sheer volume of plastic generated, inadequate management, persistent accumulation, and fragmentation exacerbate this problem. Of particular concern is the prevalence of microplastics, tiny particles measuring less than 5mm, which have permeated various natural ecosystems and have been detected within living organisms. For example, bees, due to their foraging activities, inadvertently carry microplastics and associated contaminants on their bodies. This study aims to investigate the presence of microplastics in bees (Apis mellifera), utilizing them as indicators of microplastic pollution. Additionally, it seeks to determine whether there is a correlation between proximity to urban centers and the abundance of microplastics in bees sampled from selected apiaries. Employing fluorescence microscopy and FTIR Spectroscopy, the study analyzed a total of 54 samples collected from 9 participating apiaries within the designated area. Statistical analyses revealed that Gualaceo is not immune to microplastic contamination, with fibers and synthetic fragments detected in bee specimens. Furthermore, the study found an inverse relationship between distance from urban centers and the concentration of microplastics within beehives. To advance knowledge in this field, future research could explore the extent to which microplastics are integrated into bee products and their potential impact on living organisms. These findings underscore the urgent need for a shift in attitudes and actions at both individual and institutional levels, emphasizing the importance of proactive engagement in formulating and implementing effective environmental policies and engineering solutions.

Plastic damage fracture characteristics and constitutive modeling of rocks under uniaxial compression considering crack geometry

AbstractThe study of damage and failure in fractured rock masses is crucial. This study employs the representative volume element (RVE) method to develop a microscale rock model. The model simulates the propagation and rupture of fractures by integrating factors including actual mineralogical composition, the Weibull distribution function, the Mohr–Coulomb damage criterion, and strain softening. Results indicate that fractures reduce the uniaxial compressive strength of the rock and that peak strength is significantly correlated with crack geometries. Plastic damage in rocks was categorized into three stages: elastic, rapid growth, and postpeak softening. A logistic growth model describes the plastic volume change curves for rocks with various fracture geometries, establishing the relationship between plastic damage volume and damage variables. Constitutive models for rocks with varying fracture geometries under uniaxial compression were formulated. The accuracy and applicability of these models were validated, providing a theoretical basis for rock engineering applications.

Elastoplastic finite element simulation of domino fault formation associated with tilting of highly structured ground

Ground deformation on the Earth’s surface layer is strongly affected by the nonlinearity of geomaterials. However, the formation process of such deformation has yet to be described in a unified manner based on mechanics. The present study focuses on the normal faults in a submarine ground with highly developed soil skeleton structures and attempts to reproduce the process of normal fault formation associated with the tilting of a horizontally deposited submarine ground using an elastoplastic finite element simulation. The simulation was conducted using the soil–water coupled finite deformation analysis code GEOASIA, which incorporates an elastoplastic constitutive equation of the soil skeleton based on the modified Cam-clay model and the soil skeleton structure concept. The key findings are as follows:1) Normal faults are formed from the ground surface to depth as shear bands, where shear strain is localized while exhibiting softening behavior with plastic volume compression.2) Multiple normal faults are almost equally spaced and parallel to each other, with the inter-fault blocks rotating backward. The morphology of normal faults formed by the tilting of the ground shows domino-style characteristics.3) The degree of the soil skeleton structure influences the formation of normal faults.This study demonstrates that elastoplastic geomechanics can explain the formation process of ground deformation, which has usually been interpreted from the perspectives of geomorphology and geology.

New insights into the deformation mechanism of orientation-dependent nanoindentation behaviours

Nanoindentation has been widely used to access the micro-/nanomechanical properties of materials. However, the contribution of micro-texture evolution to the anisotropic surface topography, the correlation of dislocation density characteristics with the orientation-dependent plastic volume, and the specifics of inherent slip activities, are still not fully elucidated up to now.Herein, nanoindentation simulations were performed on (001)-, (101)- and (111)-oriented single-crystal aluminium. Dominant slip systems are exactly determined for each surface pile-up for the first time. Moreover, lattice rotation facilitates the formation of pile-ups. The anisotropic plastic volume is controlled by the preference of intrinsic dislocation movement. In (001) sample, dislocations prefer to propagate along the free surface instead of into the depth of the sample, causing its most obvious pile-ups.

A Numerical Study of Reinforcement Structure in Shaft Construction Using Vertical Shaft Sinking Machine (VSM)

Using the Vertical Shaft Sinking Machine (VSM) for shaft construction is an emerging modern technology, which is also currently one of the most advanced techniques in the field of shaft sinking. Current research on VSM technology primarily focuses on mechanical and technical issues, neglecting the impact of the construction on the surrounding soil and the structure itself. This oversight leaves structural design lacking a reliable foundation. Additionally, there is insufficient information on the role of reinforcement design during construction in soft soils. These engineering challenges have hindered the widespread implementation of this new technology. Therefore, a series of numerical models were used to analyse the mechanical behaviour of shaft and soil during or after the sinking process, with the aim of addressing these gaps by investigating the influence of shafts constructed using VSM technology, and providing a scientific basis for reinforcement design in soft soil. The case study shows that increasing the soil-cement strength does not have a significant effect on the overall deformation of the soil surrounding the shaft, but leads to a notable reduction in the plastic zone volume, subsequently enhancing the overall stability of the neighbouring soil. The ring bottom beam design effectively reduces convergence deformation by about 50%, while also improving the horizontal internal force distribution near the cutting edge. However, this approach significantly escalates local vertical bending moments, necessitating thorough consideration in the design stage.

Integrating Plastic Waste into Concrete: Sustainable Solutions for the Environment.

Plastic waste management has received significant attention in recent decades due to the urgent global environmental crisis caused by plastic pollution. The versatile and durable nature of plastic has led to its widespread usage across various sectors. However, its nonbiodegradable nature contributes to unsustainable production practices, leading to extensive landfill usage and posing threats to marine ecosystems and the food chain. To address these environmental concerns, numerous challenges have been recently addressed through investigating alternative approaches for disposing of plastic waste, with the construction sector emerging as a promising option. Incorporating plastic waste materials into concrete not only offers economic benefits but also provides a valid alternative to conventional disposal methods. This paper presents the results of different experimental studies, some of them available in the literature and others new, discussing the feasibility of integrating plastic waste into concrete and its impact on mechanical properties. The influence of different sizes, natures, treatments, and percentages of plastic waste in the concrete mixtures is dealt with in order to provide further data for helping to understand the nonunivocal results in the literature, under the conviction that only further observations can help to understand the mechanics of concrete with plastic aggregates. The experimental investigation highlighted that one parameter that is better than others and can be considered to compare different experimental investigations is the variation in weight (due to the effective volume of plastics in the mix), determining a sort of increasing of porosity that degrades the mechanical characteristics. However, this seems inconsistent in some cases. Therefore, the need for further research is highlighted to refine production methods and optimize mix designs.

Thermal-mechanical modelling on cumulative freeze-thaw deformation of porous rock in elastoplastic state based on Drucker-Prager criterion considering dilatancy

The comprehensive understanding of freeze-thaw (F-T) deterioration and deformation properties of rock is a critical basis for frost damage prevention on cold regional rock engineering. In freezing process, plastic strain generates in rock when the stress induced by pore ice pressure (PIP) becomes higher than yield strength, and unrecoverable deformation accumulates in rock under multiple F-T cycles. Therefore, this study presents a thermal-mechanical modelling on cumulative F-T deformation of rock under cyclic F-T action. In the modelling of mechanical action, the microporomechanics theory is applied with a spherical element model in the derivation of equilibrium equations of rock, and the Drucker-Prager criterion is utilized with dilatancy effect of rock considered to describe unrecoverable plastic deformation cumulated in rock under multiple F-T cycles. The thermal process is modelled with unfrozen water content and latent heat accounted. The proposed thermal-mechanical modelling method is validated based on experiments and numerical simulations of F-T deformation of sandstone, and it is able to simulate the temperature and F-T deformation of rock in acceptable precision. The numerical distributions of temperature, PIP, maximum principal strain and displacement are exhibited and show that the plastic region begins to develop in rock matrix with PIP exceeding the elastoplastic critical pressure when temperature drops to about −2 °C and grows rapidly when temperature drops from −2 to −6 °C. Several F-T cycles later, large unrecoverable plastic strain remains in sandstone though PIP dissipates after thawing. The cumulative F-T deformation, porosity increment and maximum of plastic volume ratio are much greater under condition with freezing temperature of −20 °C, compared with condition −10 °C. Besides, as cycle number increases, the plastic volume ratio becomes smaller and its decrease rate attenuates.

Dynamic response and seismic vulnerability assessment of the near-fault steep slope

Existing field data demonstrates that structures situated near faults, such as slopes, dams, and bridges, are particularly vulnerable to damage. Near-fault ground motions exhibit marked disparities from their far-field counterparts, necessitating thorough investigation. This study conducts a comprehensive analysis of ground motion characteristics utilizing response spectra, Hilbert-Huang Transform (HHT), and marginal spectra to discern near-fault pulse-like ground motions (PLGMs), near-fault non-pulse-like ground motions (NPGMs), and far-fault ground motions (FFGMs). PLGMs distinguished by their heightened energy content, typically induce more pronounced amplification effects compared to NPGMs and FFGMs. Employing an efficacy criterion, optimal intensity measures (IMs) are identified and linked to dynamic response, referred to as engineering demand parameters (EDPs). Velocity-based IMs demonstrate substantial correlations across diverse ground motion types for both plastic volume ratio (PVR) and crest displacement (Dc). Lastly, probabilistic seismic demand models are leveraged to establish seismic vulnerability curves for steep slopes exposed to PLGMs and NPGMs. Notably, with Dc as the EDP, the exceedance probabilities associated with the three IMs under PLGMs generally surpass those under NPGMs. This underscores the propensity of PLGMs to trigger larger displacements in slopes, rendering them more prone to failure.

A New CRITIC-GRA Model for Stope Dimension Optimization Considering Open Stoping Stability, Mining Capacity and Costs

In the long-hole stage open stoping with subsequent backfill mining of underground metal mines, the selection or optimization of stope dimension parameters is significant for safe and economic mining operations. To analyze the optimal stope sizes, the Mathews empirical graph method and FLAC3D numerical method can be used, but the analyzed safety results of the two methods are generally independent from each other. More importantly, economic indicators including production capacity and mining costs should be considered simultaneously to optimize the stope dimension which was mostly ignored in previous reports. In this paper, a new CRITIC-GRA model was proposed for the first time to build up a multi-factor quantitative optimization for stope dimension, which allows for a comprehensive analysis with preset influential safety and economic indicators. The indicators considered include the safety indicators such as stability probability for the side walls and roof of the open stope via the updated Mathews graph method, maximum displacement, plastic zones volume and maximum principal stress via FLAC3D simulations, as well as economic indicators such as mining costs and stope production capacity in mine operations. The model was then illustrated in an underground iron mine. With the given rockmass quality in the mine, the overall stability of the open stope can be improved instead of reduced to enlarge the single stage stope height (60 m) to a double stage height (120 m) by reducing the stope width from 20 m to 15 m, thereby significantly increasing the mineable ore amount and improving the stope safety. An integrated evaluation of open stope stability, mining capacity and costs objectively determined that scheme No. 10, with a slope length of 50 m, a width of 15 m and a height of 120 m, was the optimum out of the 20 preset schemes. The new CRITIC-GRA model offers a dependable reference tool for determining the optimal stope dimensions in similar underground mines.

Solid Waste Generation and Management Practices at Sherubtse College

The enduring challenge of waste management poses a significant and ongoing global concern, demanding urgent and concerted efforts for sustainable solutions. Waste-related issues, ranging from inadequate disposal to the overwhelming volume of single use plastics, have consistently plagued communities worldwide. In light of these challenges, this study seeks to contribute valuable insights toward the development of effective strategies on both local and global fronts. The study sampled student hostels and staff quarters to understand the waste generation and management practices at Sherubtse College. Dry wastes were collected over a period of 9 weeks. Through the segregation and quantification carried out weekly, it is known that, about 0.07 kilogram(kg) of dry waste was generated by each student and 0.34 kg per staff household in a day. Among the dry waste collected, papers weighed the most. A survey was also conducted on wet waste generated on campus. It was found that per day about 0.64 kg of wet waste was generated by each staff household and 1.41 kg per hostel. In our quest to minimize waste, the analysis of quantified waste serves as a foundational starting point, providing a crucial understanding of production patterns and guiding targeted efforts toward effective waste reduction.

Impact of COVID-19 on facial plastic surgery volumes: A large database analysis of pre- and post-pandemic trends.

During the COVID-19 pandemic, elective surgeries faced cancelations due to quarantine measures. The objective of this study was to assess facial plastic and reconstructive surgery (FPRS) volume before, during, and after the height of the pandemic on a national scale. The TriNetX Research Network identified 68,101,098 individuals aged 18+ with healthcare interactions from 2017 to 2022. Rates of common FPRS surgeries and procedures were compared during March-August of each year, aligning with the pandemic lockdown. Compared to immediately before the pandemic in 2019, the 2020 pandemic peak saw an overall surgical volume reduction of -36.8%, with specific surgeries decreasing significantly: rhinoplasty (-28.6%), septoplasty (-34.0%), rhytidectomy (-54.9%), blepharoplasty (-40.7%), brow lift (-43.8%), ectropion/entropion repair (-35.6%), repair of blepharoptosis (-45.6%), correction of lagophthalmos (-29.9%), correction of lid retraction (-36.8%), and lipectomy (-41.8%) (p < .001). The procedural volume also decreased by 28.6%, encompassing reductions in various procedures: botulinum toxin A (-18.7%), facial filler (-40.7%), dermabrasion (-62.3%), chemical peel (-36.6%), and intralesional injection (-33.3%) (p < .001). In contrast to 2020, 2021 witnessed an increase of +75.0% in total surgical and +61.3% procedural volume: rhinoplasty (+81.0%), septoplasty (+74.7%), rhytidectomy (+143.4%), blepharoplasty (+81.7%), brow lift (+64.5%), ectropion/entropion repair (+55.2%), repair of blepharoptosis (+62.7%), correction of lagophthalmos (+39.0%), correction of lid retraction (+73.0%), lipectomy (+121.2%), botulinum toxin A (+52.4%), filler (+59.6%), dermabrasion (+91.8%), chemical peel (+78.8%), and intralesional injection (+67.3%) (p < .001). In 2022, rates of total surgeries (+8.5%) and procedures (+12.8%) surpassed pre-pandemic levels from 2019 (p < .001). FPRS experienced significant pandemic-induced decreases, followed by a notable recovery in subsequent years, with certain surgeries and procedures surpassing pre-pandemic levels. 4.

Extracranial-Intracranial Microsurgical Bypass Using a Y-Shaped Vein Graft From the Hand.

While extracranial-intracranial (EC-IC) bypass is commonly performed by neurosurgeons with specific expertise in cerebrovascular surgery, they can also be performed together with microvascular plastic surgeons. At our institution, some EC-IC bypass cases have evolved to be performed by neurosurgeons and plastic surgeons in a combined approach. Given the plastic surgeons' expertise and volume of experience in performing microvascular surgery, their skills are utilized in performing the donor vessel dissection as well as the bypass itself. This paper outlines a Canadian perspective on collaboration between plastic surgeons and neurosurgeons in performing EC-IC bypass along with a case report illustrating the use of a dorsal hand Y-shaped vein graft for EC-IC bypass, which has not been described in the literature to date.

Preparation and evaluation of novel biodegradable Kombucha cellulose-based multi-layered composite tableware

A huge volume of single-use plastics is used for food packaging and cutlery which is associated with significant negative environmental impacts. In this study, the facile fabrication of multilayered composites using kombucha cellulose (KC) intercalated with tannery waste-gelatin as bio-adhesive using layer-by-layer assembly followed by hydraulic heat compression technique is reported. The prolonged fermentation of Kombucha tea resulted in KC pellicle with productivity of 385.5 ± 71.4 g/L and thickness of 2 ± 0.7 cm. The purification process improved the crystallinity index of the KC layer from 41.17% to 86.2%. Gelatin prepared using tannery trimming waste along with glucose at varying concentrations was used as interlayer coating between cellulose layers crosslinked by Maillard reactions resulting in the formation of biologically benevolent ‘melanoidins’. Heat crosslinked composite (S8–20 H) with 8 layers of KC held with gelatin-glucose-myrobalan tertiary complex exhibited a high tensile strength of 47.7 MPa and a flexural strength of 117.27 MPa indicating high mechanical stiffness with the least density value of 0.71 g/cm3. The hardness values of the composites were between 54 and 76.6 Shore D hardness. The moisture susceptibility and thermal stability of the composites were found to be optimum for its use as cutlery. The composites were shaped into spoon-like tableware, ergonomically designed to appease, with baked food-like color, texture, and fragrance. The aqueous tolerance and surface oil resistance exhibited by the tableware were superior to traditional wood-based cutlery. By mechanical disintegration, the tableware is fully recyclable as a value-added bio-fertilizer for effective plant growth. This work presents a sustainable waste-to-wealth approach towards the preparation of food-safe, environment–friendly and biodegradable substitutes for plastics intended for tableware applications.

Analisis Konsistensi Volume Output Pada Nozzle Barrel Mesin Mini Injeksi V-Line Menggunakan Material Plastik Polypropylene ExxonMobil AP03B

One of the processes commonly used in making plastic goods is the injection molding process. Every process in injection molding has a very important role. A less-than-perfect process will result in defects or failure in the product. To reduce product defects, one of the processes that must be researched is the barrel purging process. The purging volume on the mini injection machine using the V-line method is inconsistent, as evidenced by the fact that if the purging waste, or what is usually called an avalanche is weighed, it will produce a non-uniform mass. This research uses a mini injection machine with the V-line method which has 2 main steps to carry out the plastic injection process; dosing and injecting. Unlike injection engines in general, this engine does not have a check-ring to withstand back pressure. This machine uses a shut-off system as a replacement for the check-ring role. This machine has never been subjected to a purging volume consistency testing process. The consistency of the purging volume greatly influences the product uniformity results. The research method used in this final assignment is direct. Data collection and test specimen collection will be taken directly on the mini injection machine using the V-line method. The steps taken in this research are planning, taking data, taking test specimens, processing test specimen data, and comparing test specimen data to obtain analysis results. The research results show that the mini V-line injection machine cannot support mass production, because increasing the screw rotation speed will affect the consistency of the volume of plastic that will be produced in the barrel, causing production to not run quickly and precisely.

Conceptual framework for identifying polymers of concern

With the increasing global concern over plastics' environmental and human health impacts, the urgency for effective regulatory measures is evident. The UN Environment Assembly's initiative to establish an international, legally binding instrument via the Intergovernmental Negotiating Committee (INC) on Plastic Pollution marks a significant step toward addressing this issue. However, the vast diversity of plastic types and their myriad applications present a complex challenge in pinpointing the most critical targets for regulation. This study builds on the existing body of literature to outline potential key criteria for identifying Polymers of Concern (PoC). We recommend a dual-focused definition of PoCs considering both (1) the type of the plastics and (2) their domain of applications based on the environmental and human health impacts throughout the polymer's life cycle. Recognizing the current gaps in our understanding of the full spectrum of plastics' impacts across their life cycles, we suggest adopting a precautionary approach that factors in the volume of plastics entering natural ecosystems alongside their life cycle impacts as reported in the literature. We then bring forward existing data on the assessment of some of the main polymer types and applications. We propose that policymakers examine a wide spectrum of strategies including not only bans and phaseouts but also economic incentives, innovation, and the redesign of plastic materials and products to mitigate the adverse impacts of PoCs. We further emphasize the importance of thoroughly assessing the feasibility, costs, and environmental, social and economic implications of alternative materials to avoid “regrettable substitution.” We conclude by identifying existing knowledge gaps and emphasizing the need for further research to refine the proposed criteria for identifying PoCs.