Release Of Debris Research Articles

Experimental Analysis of In Situ Fenestration of Endovascular Stent-Grafts: Comparison between Needle and Laser Puncture

To evaluate the quality of in vitro fenestrations during in situ fenestration (ISF) and investigate the differences between needle and laser puncture in current stent-grafts. An in vitro study evaluated the damage created by needle ISF on stent-graft fabrics versus laser ISF. Fenestrations were made in 5 different commercially available stent-grafts, including polyester stent-grafts (Relay, Valiant and Hercules) and expanded polytetrafluoroethylene (ePTFE) stent-grafts (TAG and Ankura). Each stent-graft received fenestration by needle and laser separately, followed by gradual dilation (4 mm, 6 mm, 8 mm, and 10 mm sequentially) of noncompliant balloons. Quantitative and qualitative evaluations including fenestration diameter, area, shape and margins were conducted using light microscopy and scanning electron microscope. The primary fenestrations created by needle were slit-like with visible cut-off fibers in polyester stent-grafts and were almost circular with clear margins in ePTFE stent-grafts; those created by laser were squared or elliptical with ragged edges and burned fibers in all the stent-grafts. Fabric debris and toxic particles due to burning of the material were generated during laser-assisted fenestration. The Primary holes in polyester stent-grafts (Relay, Valiant and Hercules) by needle showed smaller area (0.05 mm2 vs. 0.22 mm2, 0.52 mm2 vs. 0.70 mm2 and 0.28 mm2 vs. 0.46 mm2; P < 0.01) and worse shape (0.93 vs. 2.46, 1.17 vs. 2.33 and 0.93 vs. 2.47; P < 0.01) than those by laser, while larger area (0.67 vs.0.43, 0.59 vs.0.45; P < 0.05), better shape (3.93 vs. 2.53, 3.90 vs. 2.93; P < 0.05) and better margin (3.83 vs. 2.47, 3.83 vs. 2.53; P < 0.05) in ePTFE stent-grafts (TAG and Ankrura). After gradual balloon dilation, the final holes showed no evident difference in maximal length, fenestration area, scores of shape and margin between the 2 ways of fenestration (P > 0.05). Ankura stent-graft showed the largest holes with best quality than the others. The primary fenestrations were different between needle and laser puncture, laser induced fabric debris and toxic particles release should be cautiously considered. The final fenestrations were similar after gradual balloon dilation.

Strategies for Response and Mitigation of Marine Environmental Damage Caused by Plastic Debris

Environmental damage caused by marine plastic debris occurs and has become a major contributor to marine pollution. This study analyzed the current state of marine plastic debris pollution and proposed essential strategies to reduce damage. To assess the current state of pollution arising from marine plastic debris, this study investigated the properties of plastic debris, reviewed case studies of ecological impacts, and examined the inflow and distribution of marine plastic debris. The results of this study indicate that the major deleterious effects of marine plastics are entanglement and ingestion. In addition, the amount of plastic waste entering the sea was estimated to be 230 Mt in 2015 and may increase to 554 Mt in 2050. In this study, three key strategies were proposed to reduce damage and preserve the ecosystem, including: 1) removing plastic debris in the marine environment, 2) limiting the release of plastic debris to the marine environment, and 3) preventing damage to humans and marine life from plastic debris. To minimize the environmental damage caused by marine plastic debris, the proposed response strategies should be implemented in parallel.

A Preliminary Analysis of the Wear Pathways of Sliding Contacts on Temporomandibular Joint Total Joint Replacement Prostheses

In the last years, several materials and design have been assessed in an attempt to improve the mechanical performance of temporomandibular joint total joint replacement (TMJ TJR) prostheses. However, the wear of the TMJ TJR condyle to the polymer-based fossa component during loading and sliding movements. That promotes the release of debris and risks of toxicity to the surrounding tissues. The purpose of this study was to perform a narrative literature review on the wear of TMJ TJR sliding contacts and potential toxicity of metallic debris to the patients. Previous studies reported a significant deterioration of the sliding contact surfaces of TMJ TJR prostheses. Material loss as a result of wear can cause a TMJ TJR condyle/fossa mismatch and the modification of the contact pressure and chewing loading. As a further consequence of wear, metal particles are released to the surrounding tissues with a high risk of local tissue and systemic toxicity through the bloodstream. The presence of particles induces the stimulation of inflammatory reactions depending on the concentration and size of debris. Thus, CoCr-based condyle release metallic ions and sub-micron particles that can be engulfed by macrophages or internalized by other tissue cells. The wear and material loss of TMJ TJR could be decreased by design optimization and novel materials with low friction and contact pressure. That consequently decrease the amount of metallic ions and particles to the surrounding tissues, preventing peri-prosthetic inflammatory reactions.

Comparison and appraisal of techniques for the determination of material loss from tapered orthopaedic surfaces

This review examines the challenges associated with quantifying material loss at modular junctions. Determination of material loss from retrieved orthopaedic surfaces is regarded as a prerequisite for the evaluation of long-term implant performance. Methods previously adopted to overcome the challenges associated with determining material loss from non-articular surfaces will be presented and discussed in this paper.Total Hip Replacement (THR) is regarded as one of the most successful and cost-effective surgical interventions for the treatment of advanced osteoarthritis. The use of modular components offers surgeons an array of possible implant combinations to intraoperatively optimise range of motion and soft tissue tension. However, the taper interface used to connect modular components has been suggested to contribute to premature implant failure through the release of metal debris and corrosion products. Geometrical and topographical measurement of explanted modular interfaces has been used to correlate multifarious variables with an absolute volumetric value for material loss. To improve modular implant performance, medical device manufacturers have adopted numerous design philosophies, each presenting a unique set of challenges for the measurement of material loss. This review summarises the approaches used in previous studies to overcome these challenges and identifies future work required in this area. This field of research is currently the subject of discussion within standards bodies to create recommended best practices for centres to follow.

Simultaneous application of diamond-like carbon coating and surface amination on polyether ether ketone: Towards superior mechanical performance and osseointegration

Poor osseointegration ability and the release of worn debris after implantation are the main issues impeding the clinic application of polyether ether ketone (PEEK) as orthopedics. To address these problems, we expect that the initial deposition of diamond-like carbon (DLC) coating on PEEK substrate and the subsequent introduction of amino groups onto sample surface using plasma immersion ion implantation (PIII) have the potential to simultaneously improve the mechanical performance and osseointegration. On one hand, the surface hardness is raised from 0.38 ​GPa to 2.99 ​GPa and the elastic modulus reaches 35 ​GPa after DLC deposition, while no failure is observed in the scratch tests even the loading force is up to 100 ​N. On the other hand, the introduced amino groups facilitate the adhesion, proliferation, and osteogenic differentiation of the osteoblasts in vitro, and further enhanced the peri-implant bone regeneration in vivo. With the merits of low cost, clean approach, and ease of operation, the approach described here holds great potential for biomedical applications.

Marine plastic debris in Indonesia: Baseline estimates (2010-2019) and monitoring strategies (2021-2025)

Indonesia set the mission to reduce marine plastic debris by 70% between 2018-2025 with a global significance to support the UN Sustainable Development Goal 14.1. This short communication assesses marine debris baseline estimates in Indonesia before 2020 from available contributions and provides recommendations for monitoring marine debris mitigation between 2021-2025. Widely ranging model estimates of plastic debris released into seas highlight the roles of data source, the spatial resolution of models, and in situ data to provide representative baseline values. Recognizing the strengths and uncertainties of available contributions, model outputs converge on a baseline value of 0.52 ± 0.36 million tons (Mt) per year prior to 2020 in Indonesia, therefore setting a targeted reduced number of 0.16 Mt of marine debris releases in 2025. The Indonesian Institute of Sciences showed a preliminary value of plastic debris accumulation in beaches at 113.58 ± 83.88 g/m2 monthly or equivalent to 0.40 Mt/year by assuming plastic debris is most pervasive within 3 meters from Indonesia’s 99,093 km-long coastlines. It is important to distinguish that while river monitoring data informs land-based plastic debris releases, stranded beach debris represents a fraction of debris that is not present in the water column and bottom sediments. Moving forward, monitoring initiatives to mitigate marine debris should leverage on nationwide municipality-level model estimates (e.g., the source to leakage route framework of the National Plastic Action Partnership) as well as in situ river and coastal particularly but not limited to sites co-identified in previous monitoring studies (i.e., Medan, Batam-Bintan, Padang, Jakarta-Seribu Islands, Semarang, Pontianak, Bali, Lombok, Makassar, Manado, Bitung). The latter should be conducted at least seasonally, considering evidence of monsoonal variations of marine debris release and accumulation in Indonesia. Indonesia's vastness and regional diversity require coordination among stakeholders (government agencies, research institutions, universities, NGOs, citizen scientists) to monitor progress in the environments.

Nano-tribological behavior of graphene nanoplatelet–reinforced magnesium matrix nanocomposites

Abstract The corrosion resistance and wear resistance of metallic biomaterials are critically important for orthopedic hard-tissue replacement applications because the lack of such properties not only adversely affects their mechanical integrity but also allows the release of wear debris into the human body. In this study, the potential of zirconium (Zr) as an alloying element and graphene nanoplatelets (GNPs) as a nano-reinforcement material were investigated in relation to improving the tribological performance of pure magnesium (Mg). The GNPs–reinforced Mg matrix nanocomposites (MNCs) were fabricated using powder metallurgy. Results indicate that additions of 0.5 wt.% Zr and 0.1 wt.% GNPs to Mg matrices significantly improved the wear resistance by 89% and 92% at 200 µN load, 60% and 80% at 100 µN load, and 94% and 93% at 50 µN load, respectively, as compared to the wear resistance of pure Mg. The wear depth and coefficient of friction of the MNC containing 0.5 wt.% Zr and 0.1 wt.% GNPs (Mg0.5Zr0.1GNPs MNC) were considerably reduced as compared to pure Mg and Mg0.5Zr. Our results demonstrate that the Mg0.5Zr0.1GNPs MNC is promising for orthopedic applications in relation to its excellent tribological performance.

Tribocorrosion Susceptibility and Osseointegration Studies of Silicon–Carbon–Titanium Oxide Coatings Produced on SS316L by Laser Cladding

Metallic implants are frequently exposed simultaneously to cyclic micromovements and a corrosive medium at the interface between implant and bone, constituting a tribocorrosive environment. Ions from natural body fluids can increase the release of debris in the wear zone. This debris can penetrate soft or hard tissue, leading to implant failure and metallic contamination of the tissues around the prosthesis. Surface modification of implants has been studied to improve the lifespan of metallic implants in the body. In this work, a CO2 laser was used to irradiate silicon carbide with and without anatase titanium oxide (TiO2), in order to produce protective coatings for improving the tribocorrosion and osseointegration performance of stainless steel (SS316L). Tribocorrosion resistance and osseointegration tests were performed using simulated body fluid (SBF), in order to understand the behavior in this environment. Chemical composition and hardness analyses showed that the coatings were effective in improving passivation of the surface, when compared to bare SS316L. Osteoblasts were well dispersed on these surfaces, displaying improved proliferation and viability, compared to the SS316L sample. A statistically significant increase of cell viability was observed when the surface was covered with a low silicon content coating.

Tribological Characterization of AlCrN, AlTiN, AlTiON, and AlCrON Coatings on CoCrMo Alloy

CoCrMo alloys are commonly used in artificial joints. However, tribocorrosion phenomena have led to the search for improvements to diminish wear debris and ion release. Engineering of surfaces is an alternative to achieve this purpose. In the present study the tribological effect of AlCrN, AlTiN, AlTiON, and AlCrON coatings deposited on cast CoCr alloy was investigated. The coatings were deposited by the physical vapor deposition (PVD) sputtering technique. Adhesion of the coatings was determined with a scratch tester by identifying critical loads at different failure levels. A ball-on-disc tribometer was used to assess the wear behavior using Ringer’s solution as the lubricant. Samples were characterized with metallographic techniques, scanning electronic microscopy (SEM), profilometry to measure roughness (Ra ) and wear, and microhardness tests. In the AlTiON and AlCrON coatings the porosity was diminished and the hardness increased due to the presence of oxygen. However, the tribological performance was poor. The AlTiN coating exhibited high adherence and wear resistance even though it also presented the lowest hardness.

Isotope ratio mass spectrometry and spectroscopic techniques for microplastics characterization

Micro- and nano-scale plastic particles in the environment result from their direct release and degradation of larger plastic debris. Relative to macro-sized plastics, these small particles are of special concern due to their potential impact on marine, freshwater, and terrestrial systems. While microplastic (MP) pollution has been widely studied in geographic regions globally, many questions remain about its origins. It is assumed that urban environments are the main contributors but systematic studies are lacking. The absence of standard methods to characterize and quantify MPs and smaller particles in environmental and biological matrices has hindered progress in understanding their geographic origins and sources, distribution, and impact. Hence, the development and standardization of methods is needed to establish the potential environmental and human health risks. In this study, we investigated stable carbon isotope ratio mass spectrometry (IRMS), attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy, and micro-Raman spectroscopy (μ-Raman) as complementary techniques for characterization of common plastics. Plastic items selected for comparative analysis included food packaging, containers, straws, and polymer pellets. The ability of IRMS to distinguish weathered samples was also investigated using the simulated weathering conditions of ultraviolet (UV) light and heat. Our IRMS results show a difference between the δ13C values for plant-derived and petroleum-based polymers. We also found differences between plastic items composed of the same polymer but from different countries, and between some recycled and nonrecycled plastics. Furthermore, increasing δ13C values were observed after exposure to UV light. The results of the three techniques, and their advantages and limitations, are discussed.

Emerging Roles of Perivascular Mesenchymal Stem Cells in Synovial Joint Inflammation.

In contrast to the significant advances in our understanding of the mesenchymal stem cell (MSC) populations in bone marrow (BM), little is known about the MSCs that are resident in the synovial joint and their possible roles in the tissue homeostasis, chronic inflammation as well as in repair. Neural crest is a transient embryonic structure, generating multipotential MSC capable of migrating along peripheral nerves and blood vessels to colonize most tissue types. In adult, these MSC can provide functional stromal support as a stem cell niche for lymphocyte progenitors for instance in the BM and the thymus. Critically, MSC have major immunoregulatory activities to control adverse inflammation and infection. These MSC will remain associated to vessels (perivascular (p) MSC) and their unique expression of markers such as myelin P0 and transcription factors (e.g. Gli1 and FoxD1) has been instrumental to develop transgenic mice to trace the fate of these cells in health and disease conditions. Intriguingly, recent investigations of chronic inflammatory diseases argue for an emerging role of pMSC in several pathological processes. In response to tissue injuries and with the release of host cell debris (e.g. alarmins), pMSC can detach from vessels and proliferate to give rise to either lipofibroblasts, osteoblasts involved in the ossification of arteries and myofibroblasts contributing to fibrosis. This review will discuss currently available data that suggest a role of pMSC in tissue homeostasis and pathogenesis of the synovial tissue and joints. Graphical abstract.

3D thixo-printing: A novel approach for additive manufacturing of biodegradable Mg-Zn alloys

A simple and widely used additive manufacturing technique for polymeric materials is fused filament fabrication (FFF). In the semi-solid state, metallic materials may show rheological features comparable to those of polymers. Thus, they can be processed accordingly. The use of biodegradable Mg-based materials is an interesting approach to avoid removal surgeries and release of toxic corrosion products and wear debris. Therefore, in this study, the FFF technique was applied using a biodegradable Mg-Zn alloy in the semi-solid state. Some preliminary compositions were investigated through thermodynamic simulations to verify their compatibility with the process. Among them, Mg-38Zn was selected to be experimentally evaluated. Metallic filaments were produced via hot extrusion, which also aided in obtaining a globular microstructure in the semi-solid state. FFF was performed at 420 °C without any obstruction at the nozzle channel, which allowed the production of sound parts with acceptable welding between the deposited layers. This indicated that this technique (termed as “3D thixo-printing”) provides a promising additive manufacturing route to produce biodegradable Mg-based implants.

Blockade of XCL1/Lymphotactin Ameliorates Severity of Periprosthetic Osteolysis Triggered by Polyethylene-Particles

Periprosthetic osteolysis induced by orthopedic implant-wear particles continues to be the leading cause of arthroplasty failure in majority of patients. Release of the wear debris results in a chronic local inflammatory response typified by the recruitment of immune cells, including macrophages. The cellular mediators derived from activated macrophages favor the osteoclast-bone resorbing activity resulting in bone loss at the site of implant and loosening of the prosthetic components. Emerging evidence suggests that chemokines and their receptors are involved in the progression of periprosthetic osteolysis associated with aseptic implant loosening. In the current study, we investigated the potential role of chemokine C-motif-ligand-1 (XCL1) in the pathogenesis of inflammatory osteolysis induced by wear particles. Expressions of XCL1 and its receptor XCR1 were evident in synovial fluids and tissues surrounding hip-implants of patients undergoing revision total hip arthroplasty. Furthermore, murine calvarial osteolysis model induced by ultra-high molecular weight polyethylene (UHMWPE) particles was used to study the role of XCL1 in the development of inflammatory osteolysis. Mice received single injection of recombinant XCL1 onto the calvariae after implantation of particles exhibited significantly greater osteolytic lesions than the control mice. In contrast, blockade of XCL1 by neutralizing antibody significantly reduced bone erosion and the number of bone-resorbing mature osteoclasts induced by UHMWPE particles. In consistence with the results, transplantation of XCL1-soaked sponge onto calvariae caused osteolytic lesions coincident with excessive infiltration of inflammatory cells and osteoclasts. These results suggested that XCL1 might be involved in the development of periprosthetic osteolysis through promoting infiltration of inflammatory cells and bone resorbing-osteoclasts. Our further results demonstrated that supplementing recombinant XCL1 to cultured human monocytes stimulated with the receptor activator of nuclear factor kappa-B ligand (RANKL) promoted osteoclastogenesis and the osteoclast-bone resorbing activity. Moreover, recombinant XCL1 promoted the expression of inflammatory and osteoclastogenic factors, including IL-6, IL-8, and RANKL in human differentiated osteoblasts. Together, these results suggested the potential role of XCL1 in the pathogenesis of periprosthetic osteolysis and aseptic loosening. Our data broaden knowledge of the pathogenesis of aseptic prosthesis loosening and highlight a novel molecular target for therapeutic intervention.

Influence of Different Damage Patterns of the Stem Taper on Fixation and Fracture Strength of Ceramic Ball Heads for Total Hip Replacement.

Background Modularity finds frequent application in total hip replacement, allowing a preferable individual configuration and a simplified revision by retaining the femoral stem and replacing the prosthetic head. However, micromotions within the interface between the head and the stem taper can arise, resulting in the release of wear debris and corrosion products. The aim of our experimental study was to evaluate the influence of different taper damages on the fixation and fracture stability of ceramic femoral heads, after static and dynamic implant loading. Methods Ceramic ball heads (36 mm diameter) and 12/14 stem tapers made of titanium with various mild damage patterns (intact, scratched, and truncated) were tested. The heads were assembled on the taper with a quasistatic load of 2 kN and separated into a static and a dynamic group afterwards. The dynamic group (n = 18) was loaded over 1.5 million gait cycles in a hip wear simulator (ISO 14242-1). In contrast, the static group (n = 18) was not mechanically loaded after assembly. To determine the taper stability, all heads of the dynamic and static groups were either pulled off (ASTM 2009) or turned off (ISO 7206-16). A head fracture test (ISO 7206-10) was also performed. Subsequent to the fixation stability tests, the taper surface was visually evaluated in terms of any signs of wear or corrosion after the dynamic loading. Results In 10 of the 18 cases, discoloration of the taper was determined after the dynamic loading and subsequent cleaning, indicating the first signs of corrosion. Pull-off forces as well as turn-off moments were increased between 23% and 54% after the dynamic loading compared to the unloaded tapers. No significant influence of taper damage was determined in terms of taper fixation strength. However, the taper damage led to a decrease in fracture strength by approximately 20% (scratched) and 40% (truncated), respectively. Conclusion The results suggest that careful handling and accurate manufacturing of the stem taper are crucial for the ceramic head fracture strength, even though a mild damage showed no significant influence on taper stability. Moreover, our data indicate that a further seating of the prosthetic head may occur during daily activities, when the resulting hip force increases the assembly load.

Analytical modeling of contact mechanics of helical gear tooth by considering surface roughness effects

Release of metal debris from a pair of gear teeth is a consequence of their contact. Any excessive metal debris can lead to the onset of fatigue and failure. This paper aims to derive a contact mechanics-based model to obtain the energy absorption of helical gear teeth. The proposed model includes the roughness effect of teeth contact surfaces. The mean value of the asperity summit curvature, the standard deviation of the asperity height distribution and the area density of the asperity height distribution are the three statistical parameters that describe the micron-scale surface roughness. An explicit approximation is obtained to relate the contact load and the minimum surface separation and to estimate the energy loss. Then an analytical expression is derived for the plastic energy dissipation per cycle as a function of plasticity index for gear teeth. The proposed function can be applied in the design of gears by engineers and manufacturers. Additionally, a pertinent lumped mass at the area of interaction is assumed to describe the contact frequency and damping ratio using a nonlinear dynamic model.

Lifecycle of cobalt-based alloy for artificial joints: From bulk material to nanoparticles and ions due to bio-tribocorrosion

The release of debris and ions from metallic artificial joints during bio-tribocorrosion posed a severe threat to patient health. In this work, the lifecycle of a CoCrMo alloy was presented by investigating the subsurface microstructure transformation in-vitro. The results showed that the originally coarse grains changed to nano-grains (NGs) on the top region of the alloy, and nanoparticles (NPs) were torn off the surface, which were then blocked by the tribo-film. The agglomerated alloy NPs contained in the tribo-film transformed into debris after being removed from the alloy surface. The majority of the torn-off NPs were corroded and released ions into solution due to their high chemical activities.

Prosthetic Impingement in Total Hip Arthroplasty—The Trigger for Adverse Wear

Development of total hip arthroplasty (THA) now spans more than 5 decades encompassing combinations of metal-on-metal (MOM), ceramic-on-metal (COM), metal-on-plastic (MOP), ceramic-on-plastic (COM), and ceramic-on-ceramic (COC). In every arena of extensive technical development, there exists a data set that when viewed in isolation seemed of little import, but when assembled in-toto may produce a generational shift in perception. Our review focused on two such THA events. Firstly, COC retrieval studies (1999-2001) noted habitual wear patterns on heads and peripheral wear stripes, along with femoral-neck impingement, and ceramic surfaces stained gray by metal debris. These COC data indicated THA risks included, 1) cup edge-loading (E/L) on heads producing “stripe wear”, 2) component impingement releasing metal particles resulting in 3) tissues contaminated by metal debris. A corresponding MOM impingement-debris mechanism was only perceived by Howie (2005) in a McKee-Farrar retrieval study. Our anticipation at LLUMC was that MOM retrievals would provide superior wear details to those seen on COC retrievals. We noted stripe wear in the polar zone of CoCr heads and basal stripes in the non-wear areas. The basal-polar stripe combinations were found in all MOM retrievals. Basal-polar stripe combinations followed cup-rim profiles in our LLUMC simulations of prosthetic impingement. LPUH videos demonstrated the formation of stripe wear in functional-standing and functional-sitting postures for both impingement and subluxation episodes using THA and RA designs. The stripes on CoCr heads revealed the large scratches we now term “microgrooves”. Microgroove width varied from 40 - 400 um with 100 um being typical. The longitudinal striations in microgrooves, the raised jagged lips, scratches with shallow entry and exit termini, were all indicative of a classic 3rd-body wear mechanism. The THA impingement simulations denoted four sites of edge-loading, i.e. neck-E/L, inferior cup-E/L, superior cup-E/l and head-E/L, and ingress of Ti64 particles as a contaminating-roughness effect. Individual MOM cases referred to LLUMC demonstrated dramatic evidence of neck notching. At one end of the debris spectrum, a Ti64-notch model predicting a 6 mm3 annual wear-rate represented the release of 5700 particles of 126 um-size (approximating daily release of 16 particles). At the other end of the spectrum, if metal particles were crushed between MOM surfaces to the equivalent nanometer size found in tissues, our notch model represented approximately 22-trillion Ti64 particles annually deposited in tissues. The anatomical THA models represented in LPUH videos demonstrated that even 1-degree of head subluxation from a rigid cup created a cup “lift-off” scenario (CLO) that would open a gap of 250 - 400 microns between femoral head and cup. This would void all lubrication potential and focus the total hip-joint force along the beveled cup rim, i.e. stripe wear. It is therefore interesting that MOM impingement/debris predictions by Howie et al. have not been confirmed until now or discussed in contemporary literature. Therefore, this review of 50 years of THA data demonstrated that hip impingement was always the trigger for adverse wear and that metal-backed cups represent the potential for release of metal debris at extremes of functional standing and sitting postures.

DISTRIBUTION OF ARTIFICIAL RADIONUCLIDES IN AGGREGATE FRACTIONS OF SOILS IN THE VICINITY OF UNDERGROUND NUCLEAR TESTS CONDCUTED IN BOREHOLES AT “BALAPAN” SITE

The paper provides findings on distribution of artificial radionuclides in aggregate fractions of soils in radioactive fallout plumes near two Boreholes – 1301 and 1077 (the former ‘Balapan’ testing area), in which underground nuclear tests were conducted that differed in the nature of the real radiological situation. In the vicinity of Borehole 1301 in which an underground nuclear explosion was accompanied by the unforeseen release of debris into the atmosphere, the highest accumulation of 137Cs and 90Sr occurs in 250 to 1,000 µm fractions. Distribution of 241Am and 239+240Pu is characterized by two different tendencies – the predominant enrichment of 250 to 1,000 µm fractions in the near zone of the plume (up to 250 m) and predominantly enriched fractions of 5–8 µm and &lt;1 µm in the distant plume area (700 to 2,500 m). Near Borehole 1077, near which the underground explosion is assumed to have been accompanied by escaping radioactive inert gases, 137Cs and 90Sr are mainly concentrated in less than 5 µm fractions, 241Am and 239+240Pu – in fractions of 8–40 µm and &lt;1 µm.

Major sources and monthly variations in the release of land-derived marine debris from the Greater Jakarta area, Indonesia

As marine debris becomes increasingly prevalent and induces cascading impacts on marine ecosystems, monitoring of land-derived debris is key for identifying effective mitigation strategies. Indonesia plays a pivotal role in reducing land-derived debris into the oceans considering its extensive coastline, large population and high waste production. We present the first marine debris monitoring data from Indonesia’s capital, the Greater Jakarta area, by characterizing major sources and monthly variations of debris release at nine river outlets into Jakarta Bay between June 2015-June 2016. Our data show plastics as the most common debris entering Jakarta Bay representing 59% (abundance) or 37% (weight) of the total collected debris. Styrofoam was dominating among plastic debris, highlighting the urgency of reducing plastic and styrofoam uses. Higher debris releases during the rainy season (December-February) highlight the need to intensify river clean-up activities. We estimated an average daily debris release of 97,098 ± 28,932 items or 23 ± 7.10 tons into Jakarta Bay with considerably lower inputs from the capital compared to its neighboring municipalities. Within the plastics category, field monitoring data yield a daily plastic debris release of 8.32 ± 2.44 tons from the Greater Jakarta area, which is 8–16 times less than global-scale model estimates.

Fast Door-Opening Method for Quick Release of Rock Boulder or Debris in Large-Scale Physical Model

AbstractStudy on the mitigation of debris flows and rockfalls is a very challenging topic due to complex moving and impacting mechanisms. A large-scale physical model is preferred by researchers in...