Capping Mechanism Research Articles

A Multi-objective Robust Scenario-based Stochastic Chance Constrained Programming Model for Sustainable Closed-loop Agri-food Supply Chain

The agri-food supply chain management plays a crucial role in ensuring the interests of supply chain components and food security in society. Additionally, due to the nature of agri-food products, sustainability dimensions have always been of concern to organizations engaged in this field. The importance of the timely and quality provision of agri-food products has doubled after the global crisis. Therefore, this study focuses on optimizing and analyzing the sustainable multi-objective closed-loop supply chain network for agri-food products, with a case study on the canned food under uncertainty. Strategic and operational decisions and other features are considered to achieve more accurate results. To address the various dimensions of sustainability, the problem is considered as a four-objective one, aiming to maximize the use of available production throughput for factories, maximize job opportunities created, minimize supply chain costs, and ultimately minimize unmet demands. The carbon cap and trade mechanism is used to control greenhouse gas emissions in the supply chain network. A robust scenario-based stochastic chance constrained programming approach is employed to deal with the uncertainty, and also validation is performed using various criteria. Moreover, an augmented ε-constraint optimization approach is used to solve the multi-objective problem and achieve Pareto optimal solutions. Finally, sensitivity analysis is employed to prepare for potential changes in some problem parameters.

Mechanism of actin filament severing and capping by gelsolin.

Gelsolin is the prototypical member of a family of Ca2+-activated F-actin severing and capping proteins. Here we report structures of Ca2+-bound human gelsolin at the barbed end of F-actin. One structure reveals gelsolin's six domains (G1G6) and interdomain linkers wrapping around F-actin, while another shows domains G1G3-a fragment observed during apoptosis-binding on both sides of F-actin. Conformational changes that trigger severing occur on one side of F-actin with G1G6 and on both sides with G1G3. Gelsolin remains bound after severing, blocking subunit exchange.

The relevance of dark trading for information acquisition in the German stock market

The implementation of the European double volume cap (DVC) mechanism acts as an exogenous shock to help understand how restrictions on dark trading affect the price discovery process for German stocks. Using the price jump ratio as a measure of information acquisition prior to earnings announcements, we show that dark pool trading aids information acquisition. This relationship is stronger for negative earnings news, for stocks that are hard to value, and when there is uncertainty around earnings. The introduction of the DVC mechanism weakens the relationship between dark trading and pre-announcement information acquisition.

Mechanism of Actin Filament Severing and Capping by Gelsolin.

Gelsolin is the prototypical member of a family of Ca 2+ -dependent F-actin severing and capping proteins. A structure of Ca 2+ -bound full-length gelsolin at the barbed end shows domains G1G6 and the inter-domain linkers wrapping around F-actin. Another structure shows domains G1G3, a fragment produced during apoptosis, on both sides of F-actin. Conformational changes that trigger severing occur on one side of F-actin with G1G6 and on both sides with G1G3. Gelsolin remains bound after severing, blocking subunit exchange.

Interpretation of Fairness Concept and Economic Impact Analysis of Carbon Quota Allocation between Industries in Indonesia

Abstract Quota allocation is critical in implementing supporting policies for carbon reduction efforts, such as the carbon cap and trade mechanism. Depending on the allocation rules, certain company types may benefit more economically. Inequality conditions can happen and reduce the willingness to participate in sustainability efforts. This study aims to propose fairness interpretations in the context of company-level carbon quota allocation. Four industries in Indonesia with inherently different emission and financial profiles were selected as case studies: energy, oil palm, basic materials, and finance. Fairness principles were analyzed to represent the interests of companies based on their financial and environmental performance. Indicators were selected to quantify the equality principles and aggregated into a Comprehensive Index (CI) for quota allocation, where the companies’ quota surplus/deficit is quantified into monetary value to estimate the economic impact with varying reduction targets. According to our analysis, the sectoral advantages/disadvantages would depend on the viewpoint of fairness principles, and the oil palm and financial sectors be less impacted than the basic materials and energy sectors with increased emission reduction targets. The sensitivity analysis suggests that the vertical, horizontal, polluter pays, and historical responsibility principles are more sensitive to weighting than the merit and basic needs principles.

Predictive Model Control and Intelligent Agent are Used To Optimize The Precision Control of an Electro-Pneumatic Actuator-Based Robotic Bottle Capper

The inferior corking performance observed in bottled drinks from breweries is attributed to poor precision. To address this issue, an enhanced precision control system for an electro-pneumatic actuator-based bottle capper is introduced, utilizing model predictive control and intelligent agent technologies. This involves characterizing the electro-pneumatic actuator system, developing a conventional model for the robotic bottle capper, and designing a rule base to improve precision in the capping mechanism, thereby boosting production capacity per unit time. To achieve this, AI is trained to design a rule-based model ensuring optimal efficacy of the capping mechanism, thus enhancing the brewery industry's production capacity and revenue generation. A SIMULINK model is developed to demonstrate the improved precision control of the electro-pneumatic actuator robotic bottle capper using model predictive control and intelligent agent. Results show a significant increase in corking precision from 94.4% with conventional methods to 99.9% when intelligent agents are incorporated into the system. This translates to a 5.5% improvement in corking precision, with production capacity increasing from 27,000 crates using conventional methods to 28,570 with model predictive control. Moreover, with the integration of intelligence, the production capacity further rises to 342,500 bottles.

Activity of pure flavonoid-based green silver nano particles against breast cancer: A combined experimental and computational investigation

Because of the wide range of applications in various industries, the development of novel nanomaterials is receiving more and more attention nowadays. A green route to synthesize one such versatile nanomaterial, silver nanoparticles (AgNPs) with a pure flavonoid, quercetin has been explored in this study. The reducing and capping mechanism of quercetin was examined using density functional theory (DFT). Dynamic light scattering (DLS), UV–vis spectra (UV–Vis), and Transmission Electron Microscopy (TEM) studies confirmed that the synthesized AgNPs are stable, monodispersed, spherical shaped with an average size of 16 nm. A molecular docking study has identified the epidermal growth factor receptor (EGFR) protein as a potential target for quercetin-capped AgNPs to fight against breast cancer. Molecular dynamics (MD) simulation has quantified the efficiency of quercetin-capped AgNPs over quercetin only in targeting breast cancer. These findings will be helpful in using quercetin-based AgNPs for drug discovery against breast cancer.

Implementation of the mechanism of systemic risk internalisation in the deposit market (pigou tax principle)

The deposit guarantee fund’s rate cap mechanism was supplemented by a systemic risk fee based on the Pigou tax principle. The additional systemic risk fee was introduced to curb overly aggressive price competition in the deposit market by creating additional explicit financial costs that can offset the gains to individual banks from increasing their deposit market share. However, the existing inelasticity of the implemented mechanism, manifested by the lack of stable pressure across the entire range of rates, necessitates its reform. In this article the authors reveal the details of the implemented mechanism of internalisation of systemic risk in the deposit market, the reasons that prompted its implementation, assessment of its success and ways of further reform.

Probing capping mechanisms and polymer matrix loading of biogenic vaterite CaCO3-Ag hybrid through X-ray photoelectron spectroscopy (XPS).

Despite extensive research in the literature, the synthesis of silver nanoparticles (AgNPs) via capping mechanisms remains incompletely understood. This study employs a mechanistic approach to unravel the underlying molecular interactions driving the capping process of biogenic vaterite CaCO3-Ag and explores their interactions with different polymer matrices. X-ray photoelectron spectroscopy (XPS) was used to reveal the capping mechanisms, surface composition alterations, and vaterite polymorph transitions. The oxidation states of AgNPs exhibited distinct changes under different capping agents. The Ag3d spin-orbit splitting profiles revealed the coexistence of Ag+ and Ag0 within CaCO3-Ag, with a significant presence of Ag0 when poly(sodium 4-styrene sulfonate) was employed as the capping agent. Conversely, the use of carboxy methyl cellulose as the capping agent resulted in Ag+ dominance. XPS analysis illuminated the transformation of CaCO3 polymorphs from calcite to vaterite structure, which remained stable following embedding within polymer matrices. Integrating CaCO3-Ag microspheres into polymer matrices and investigating their surface characteristics represents a strategic step toward tailoring material properties for potential applications in active packaging and biomedicine.

Risk assessment in the supply chain of hazardous materials with carbon cap and trade mechanism: multi-objective red deer algorithm

Risk assessment in the supply chain of hazardous materials with carbon cap and trade mechanism: multi-objective red deer algorithm

Piezoeletric cold atmospheric plasma induces apoptosis and autophagy in human hepatocellular carcinoma cells through blocking glycolysis and AKT/mTOR/HIF-1α pathway

Hepatocellular carcinoma (HCC) is the sixth most prevalent cancer and the fourth leading cause of cancer-related death worldwide. Advanced or metastatic HCC is currently managed using systemic drug therapy with unsatisfactory patient survival. Cold atmospheric plasma has emerged as a promising, physicochemical, and broad-spectrum oncotherapy. In this preclinical study, we investigated the anti-neoplastic functions and mechanism of piezoelectric direct discharge technology-based CAP, Piezo-CAP, on HCC in vitro and in vivo. Various HCC cells lines, such as SMMC7721, HepG2 and LM3, were used as in vitro cancer model for the phenotypic and mechanistic studies. Specifically, the cell counting Kit-8 and colony formation assay, flow cytometry, Transwell assay, Western blot, reactive oxygen species (ROS) assay, and glutathione to oxidized glutathione ratio (GSH/GSSG) assay were used to demonstrate plasma-induced changes in HCC cell proliferation, cell cycle progression, migration and invasion, epithelial-to-mesenchymal transition, intracellular ROS, and antioxidant capacity, respectively. In addition, the Acridine orange and ethidium bromide (AO/EB) staining and transmission electron microscopy were performed for cellular and subcellular assessment of HCC cell apoptosis. The Ad-mCherry-RFP-LC3B fluorescent double-labeled lentiviral system was used to detect autophagic flux. On the other hand, RNA-sequencing, quantitative real-time PCR, and Western blot were used to demonstrate plasma-induced metabolic and molecular disruption of tumor glycolysis and oncogenic proliferation, respectively. In vivo experiments using a human cell-line-derived xenograft model and immunohistochemistry (IHC) were utilized to investigate the mechanism. Piezo-CAP exerted anti-neoplastic functions through inhibiting cell proliferation, migration and invasion, and promote cell apoptosis and autophagy. Treatment of Piezo-CAP could suppress proliferation and induce autophagy of HCC cells through simultaneously disrupts cancer survival pathways of redox deregulation, glycolytic pathway, and PI3K/AKT/mTOR/HIF1α pathway signaling. Moreover, upon translation of these in vitro results into the tissue level, Piezo-CAP significantly suppressed in situ tumor growth. These findings collectively suggest that Piezo-CAP-induced apoptosis and autophagy of HCC cells though a multitargeted blockade of major cancer survival pathways of deregulated redox balance, glycolysis, and PI3K/AKT/mTOR/HIF-1α signaling.

Pricing decisions of risk averse logistic companies with carbon cap and trade under Stackelberg game.

With the implementation of the double carbon plan, this paper considers the delivery fees of two risk averse logistics companies under carbon cap and trade mechanism. We establish logistics company Stackelberg (MS) model and retailer Stackelberg (RS) model under mean variance (MV) framework, respectively. We obtain the optimal delivery fees and retail prices. We find out that the higher degree of risk aversion can lead to a lower delivery fee. We also show that a higher carbon trading price or a higher cross price sensitivity will increase delivery fees. Moreover, we indicate that the performances of logistics companies under MS scenario are higher than that RS scenario. In addition, we suggest that under the carbon cap and trade rules, in order to obtain higher profits, logistics companies should use fuel vehicle for transportation under certain conditions, and use electric vehicle in other cases.

#3760 CYTOSKELETON-ORGANELLE INTERACTION IN LIVING CELL EXPRESSING INF2 VARIANTS CAUSING FSGS AND PERIPHERAL NEUROPATHY

Abstract Background and Aims Focal segmental glomerulosclerosis (FSGS) is a common glomerular injury and represents a leading cause of ESRD. Studies with genetic FSGS show that a majority of genes are associated with regulation of podocyte cytoskeletons. INF2 is an actin assembly factor that mediates both polymerization and depolymerization and is the most frequent cause of dominant inherited FSGS. INF2 mutations located in the proximal half of DID (residues Leu57 to Glu184) typically cause CMT with early-onset FSGS, whereas that situating in the distal half (residues Glu184 to Leu245) cause FSGS alone. Previous studies disclosed that INF2 mutations primarily disorganize actin network and alter mitochondria shapes and vesicle motility. However, it remains elusive how the cytoskeletal network is concerted with the organelle morphology and functions in the disease cells. This study aims to characterize the interaction between cytoskeleton and organelle in cells expressing INF2 FSGS or CMT/FSGS variants. Method We characterized the cytoskeletal-organelle interaction in live HeLa or COS-7 cells expressing pathogenic INF2 variants in our cohort of FSGS. We performed a triple labeling by co-transfection of GFP-INF2, cytoskeletal markers (Lifeact-mCherry or EMTB-mScarletI), and by the uptake of organelle markers (Lysotracker or Mitotracker). To clarify the detailed pattern and dynamics of cytoskeletons and organelles, we employed the Spinning Disk Confocal Microscope DragonFly, which allows real-time super-resolution imaging with 70nm resolution. Results Wild-type-INF2 (WT-INF2) cells showed an ER pattern with perinuclear, Golgi accumulation. Mild INF2 variants causing FSGS alone (T161N, N202S) preserved the subcellular distribution essential similar to WT-INF2, while showing focal irregularity of ER networks. In contrast, severe INF2 variants leading to CMT/FSGS (G73D) exhibited a diffuse coarse ER pattern with few Golgi clusters and occasional peripheral accumulation in both cell poles. In live imaging of cells coexpressing GFP-INF2 and Lifeact-mCherry, actin stress fibers were pronouncedly reduced in CMT/FSGS variant (G73D) cells, but were mildly decreased FSGS variant (T161N and N202S) cells, compared with WT-INF2 cells. The filopodia in cells expressing T161N variant were less mobile (n = 10, P< 0.01) but were longer (n = 10, P< 0.0001) than those in cells expressing WT-INF2. T161N variant reduced expression of cortactin that stabilizes actin-branching and narrowed area of cortical actin meshwork compared to the WT-INF2 (n = 11, P< 0.01), suggesting that INF2 could serve the cortical actin formation. HeLa cells coexpressing T161N variant and EMTB showed a bipolar cell elongation along the longitudinal axis (n≥30, P< 0.0001) and disarranged microtubule bundles aligned in parallel, compared with those expressing WT-INF2. A time-lapse imaging of living COS-7 cells revealed that T161N variant increases mitochondrial fragmentation as well as mitochondria-ER interfaces more prominent than WT-INF2. Moreover, T161N variant induced the mitochondria misdistribution at the cell periphery (filopodia and cell edge) in both cell poles. Such aberrant patterns frequently coexisted with disarranged microtubules. Moreover, in lysotracker-labeled living COS-7, T161N variant reduced the motility of the lysosomal vesicles in cortical actin meshwork area, compared with WT-INF2 (n = 100, P< 0.0001). These observations suggest that INF2 variants perturbate the trafficking of organelles through disorganization of actin-microtubule network. Conclusion Our results indicate that INF2 CMT/FSGS variants cause more global and severe organelle dysfunction by disrupting the organelle-cytoskeletal interaction, than INF2 FSGS variants. The microtubule disarrangement might be due to an insufficient capping mechanism by which the microtubules are stably tethered to the cortical actin meshwork. Elucidation of cell-specific factors will help better understanding why podocyte and Schwann cell are susceptible to the cytoskeletal disarrangement.

Production decisions in remanufacturing under the cap-and-trade considering consumer education and government subsidies

Remanufacturing, which is encouraged by the government but lacks consumer acceptance, can help manufacturers relieve carbon emission pressure under the carbon cap and trade mechanism (CCT-mechanism). In our research, there is an original equipment manufacturer (OEM) and an independent remanufacturer (IR) in the market. A game-theoretic model is constructed to discuss the optimal production decisions of the OEM and IR under the CCT-mechanism. Furthermore, the level of consumer education may affect the acceptance of remanufactured products and government subsidy, so an extended model is proposed. Then, the effects of the CCT-mechanism, government subsidies and consumer education on production decisions are analysed. The results show that the CCT-mechanism can prompt the OEM to enter remanufacturing and that the impact of the increasing rate is similar to the carbon price, but the latter is more effective. Government subsidies to the OEM are more efficient than those to the IR. Subsidization plays an important role in the early stage of remanufacturing, but it is not always necessary. IRs benefit from consumer education; however, OEMs cannot always benefit from consumer education.

Bioinspired 5-caffeoylquinic acid capped silver nanoparticles using Coffee arabica leaf extract for high-sensitive cysteine detection

Selection of plant extracts as bioactive phytochemical source to synthesize nanoparticles is highly demanding due to the biocompatibility, nontoxicity, and cost-effectiveness over other available physical and chemical methods. Here, for the first time, Coffee arabica leaf extracts (CAE) were used to produce highly stable silver nanoparticles (AgNPs) and the corresponding bio reduction, capping and stabilization mechanism mediated by dominant isomer 5-caffeoylquinic acid (5-CQA) is discussed. UV–Vis, FTIR, μRaman spectroscopy, TEM, DLS and Zeta potential analyzer measurements were employed to characterize these green synthesized NPs. The affinity of 5-CQA capped CAE–AgNPs to thiol moiety of amino acid is utilized for the selective as well as sensitive detection of L-cysteine (L-Cys) to a low detection limit of 0.1 nM, as obtained from its μRaman spectra. Hence, the proposed novel, simple, eco-friendly, and economically sustainable method can provide a promising nanoplatform in the field of biosensors compliant with large-scale industrial production of AgNPs without aid of further instrumentation.

A novel multi-objective robust fuzzy stochastic programming model for sustainable agri-food supply chain: case study from an emerging economy

On the one hand, supply chain management of agri-food products under uncertain conditions has a significant impact on food security and, on the other hand, increases the profits of supply chain components. Moreover, considering the sustainability concepts leads to more social and environmental benefits. The present study investigates the canned food supply chain under uncertain conditions and sustainability concepts by considering strategic and operational decisions and different characteristics. The proposed model is a multi-echelon, multi-period, multi-product, multi-objective location-inventory-routing problem (LIRP) in which the vehicle fleet is considered heterogeneously. The objectives of this model are to (1) minimize costs, (2) minimize customer dissatisfaction, (3) maximize production throughput, and (4) maximize job opportunities. In this study, carbon cap and trade mechanism are used to minimize environmental damage. Robust fuzzy stochastic programming (RFSP) is employed to cope and control uncertainties. The multi-objective optimization problem is implemented on a real case and solved using the Torabi and Hassini (TH) method. The results of this study showed that with increasing confidence levels, the severity of the problem increased and the values of the objective functions worsened. Also, using the relative value of stochastic solution (RVSS) criterion demonstrated that the effect of utilizing the RFSP approach on the first and second objective functions was higher than that the nominal approach showed itself. Finally, sensitivity analysis is performed on two parameters: the selling price of products to foreign customers and the cost of purchasing products from farms. The results of this study showed that changing these two parameters had a significant effect on the first and second objective functions.

Carica papaya male flower mediated environmentally benign synthesis of silver nanoparticles towards the sensing of tryptophan

Fulfilling “green chemistry” targets by incorporating environmentally benign synthesis methods into advancing nanotechnology is an alternative pathway for risk reduction and attaining sustainability. In this work, the synthesis and subsequent stabilization of silver nanoparticles (AgNPs) via a greener fashion using nutritious as well as biochemically rich Carica papaya (male) flower extract (CPFE) is introduced. The morphological and surface structural characteristic studies of CPFE-mediated AgNPs (CPFE-AgNPs) were carried out using different spectroscopic techniques. Kaempferol-dominated reduction and capping mechanism involved during the formation of CPFE-AgNPs has been discussed. The AgNPs synthesized in this study possess long-term stability with uniform size (12.30 ± 3.33 nm) and are spherical in shape.The sustainable and relevant application of phyto-fabricated CPFE-AgNPs in the biosensing of amino acid tryptophan (Trp) is investigated and highlighted its necessity over synthetic sensors that have higher toxicity.

Controlling internal nitrogen and phosphorus loading using Ca-poor soil capping in shallow eutrophic lakes: Long-term effects and mechanisms

Clean soil is a potential capping material for controlling internal nutrient loading and helping the recovery of macrophytes in eutrophic lakes, but the long-term effects and underlying mechanisms of clean soil capping under in-situ conditions remain poorly understood. In this study, a three-year field capping enclosure experiment combining intact sediment core incubation, in-situ porewater sampling, isotherm adsorption experiments and analysis of sediment nitrogen (N) and phosphorus (P) fractions was conducted to assess the long-term performance of clean soil capping on internal loading in Lake Taihu. Our results indicate that clean soil has excellent P adsorption and retention capacity as an ecologically safe capping material and can effectively mitigate NH4+-N and SRP (soluble reactive P) fluxes at the sediment-water interface (SWI) and porewater SRP concentration for one year after capping. The mean NH4+-N and SRP fluxes of capping sediment were 34.86 mg m−2 h−1 and -1.58 mg m−2 h−1, compared 82.99 mg m−2 h−1 and 6.29 mg m−2 h−1 for control sediment. Clean soil controls internal NH4+-N release through cation (mainly Al3+) exchange mechanisms, while for SRP, clean soil can not only react with SRP due to its high Al and Fe content, but also stimulate the migration of active Ca2+ to the capping layer, thus precipitating as Ca-bound P (Ca-P). Clean soil capping also contributed to the restoration of macrophytes during the growing season. However, the effect of controlling internal nutrient loading only lasted for one year under in-situ conditions, after which the sediment properties returned to pre-capping conditions. Our results highlight that clean Ca-poor soil is a promising capping material and further research is needed to extend the longevity of this geoengineering technology.

Gas-saturated carbon dioxide hydrates above sub-seabed carbon sequestration site and the formation of self-sealing cap

Storing CO2 in sub-seabed sediments is a promising CO2 sequestration method to reduce atmospheric CO2 concentrations and mitigate climate change. Leaked CO2 from the sequestration site can form CO2 hydrates in the sediment and reduce the effective permeability of the sediment layer, developing a self-sealing cap above the storage site. Previous studies usually treat the CO2 hydrate layer similarly to a methane hydrate reservoir. However, unlike methane, CO2 has a larger solubility that increases significantly with depth, leading to high gas saturation levels in the sediment. Near the base of the CO2 hydrate stability zone, CO2 free gas, CO2 hydrate and dissolved CO2 coexist, and elevated surface energies of the curved surfaces of bubbles and hydrate crystals in pores shift the phase equilibria. The bubbles entrapped in the three-phase zone help to reduce the effective permeability besides accumulate CO2 hydrates. We simulate the three-phase zone in a shallow seabed using Monte Carlo methods in packed synthetic mono-dispersed spherical sediment grains, taking into account of the surface curvatures of the gas–liquid and hydrate–liquid interfaces in irregular pore spaces constrained by the sediment grains, and estimate the permeability reduction caused by entrapped CO2 bubbles. Finer sediment grains, larger geothermal gradients and shallower seawater all tend to broaden the zone, and the effective permeability in the three-phase zone can be further reduced by up to an order of magnitude than that with hydrates only. We also analyze the sensitivity of the three-phase zone due to temperature and pressure perturbations, and the results suggest possible thickness and depth variations of the zone due to cyclic temperature and sea level changes. This work demonstrates the difference between the CO2 hydrate-bearing sediment layer and the methane hydrate reservoir, and provides insight into the formation mechanism of the self-sealing cap above the sequestration sites.

Structure, function and dynamics of alphavirus capping pores.

Positive-sense single stranded RNA viruses such as coronaviruses, flaviviruses or alphaviruses, carry out transcription and replication inside virus-induced membranous organelles within host cells. Remodelling of the host cell membranes for formation of these organelles is coupled to the membrane association of the viral replication complexes and RNA synthesis. These viral niches allow for concentration of metabolites and proteins for the synthesis of viral RNA, also preventing its detection by the cellular innate immune system. I will present the cryo-EM structural characterization of the chikungunya virus non-structural protein 1, the viral protein responsible for RNA capping and membrane binding of the viral replication machinery, and the capping mechanism. The structures show the enzyme in its active form assembled in a monotopic membrane-associated dodecameric rings. It provides the structural basis for the coupling between membrane binding and allosteric activation of the capping enzyme. We also show different stages of the reaction pathway carried out by the enzyme, showing how nsP1 pores recognize the substrates of the methyl-transfer reaction, GTP and SAM, how it reaches a metastable post-methylation state with SAH and m7GTP in the active site, the subsequent covalent transfer of m7GMP to nsP1 and post-reaction conformational changes triggering the opening of the pore. In addition, we biochemically characterize the capping reaction, demonstrating specificity for the RNA substrate and the reversibility of the cap transfer resulting in decapping activity and the release of intermediates of the reaction. Our data identify the molecular determinants allowing each transition, provide explanation for the need for the SAM methyl donor all along the pathway and new clues about the conformational rearrangements associated to the enzymatic activity of nsP1. Together our results set new ground for the structural and functional understanding of alphavirus RNA-capping and the design of antivirals.