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An Experimental and Modeling Study of CaCO3 Nucleation and Inhibition Under a Dynamic Oversaturation Regime with Implications for Energy Production from Subsurface Reservoirs
No full textEnergy production from subsurface reservoirs perturbs the equilibrium between fluids and the surrounding rocks. As the saturation increases, nucleation begins, forming a scale that is detrimental to production. Inhibitor addition for scale prevention is a common practice with significant economic and environmental costs. Traditional experiments to determine induction times (tind) and evaluate inhibitor efficiency are performed under constant oversaturation. Similarly, constant oversaturation is used in both the empirical and the classical nucleation theory modeling schemes used for scale prediction. Subsequently, experiments and models do not address the dynamic nature of oversaturation increase during energy production. We developed an experimental system for quantitative investigation of nucleation kinetics under a regime of dynamic oversaturation and a simple algorithm for determining tind from laser measurements. Using our system, we studied the precipitation kinetics of CaCO3 minerals at a pH of ~6.76, ionic strength of I = 1m, temperature range of 50-90 oC, and varying rates of oversaturation increase. We quantified the effect of a potent inhibitor (Polyamino Polyether Methylene Phosphonate; PAPEMP) on the tind and the forming solid phase. Finally, we developed a numerical model that explicitly accounts for the dynamic nature of oversaturation. Here, we present our experimental system, results, and modeling scheme. We show that for a given set of conditions, calcite induction occurs at a similar oversaturation, regardless of the rate at which oversaturation increases. Moreover, we show that PAPEMP retards CaCO3 nucleation at below ppm levels and that it has a temperature-dependent effect on polymorphism. Lastly, we suggest that expanding existing models such that: t_ind=f(∆SI)*f(static) Where f(ΔSI) is a function of oversaturation with time and f(static) are existing modeling schemes, adequately describe the dynamic nature of oversaturation and show a form of f(ΔSI) that provides an excellent fit with measured tind
Sustainable Development in the Plastic Industry: A Promising Future or Just a Hoax? Past, Present, and Future Perspectives from a Global Viewpoint
No full textThe issue of fossil-based plastics presents a paradox, with conflicting solutions proposed. While an idealistic vision promotes biodegradable plastics as the ultimate solution, the reality is that fossil-based plastics dominate production, constituting approximately 99%. Despite the conceptual appeal of biodegradable plastics, their practical implementation remains limited with minimal production. Consequently, the current plastic waste management system faces challenges, with only 25% of total plastic waste being recycled. A significant portion, around 31.2%, is incinerated, and 43.8% ends up in landfills or is improperly disposed of, reflecting a non-sustainable approach. Projections suggest a potential increase in recycling rates to nearly 44% by 2050, but incineration remains alarmingly high at close to 50%. To achieve sustainable growth and create a carbon and toxic-free environment, there is a need for a renewed commitment to accelerate the reuse and recycling of plastic waste. Failure to do so risks perpetuating the condemnation of fossil-based plastics, despite their significant historical contributions to society and the environment
Light-triggered stapling of biologically relevant DNA tetraplexes results in increased topological, thermodynamic, and metabolic stability.
No full textG-quadruplexes (G4s) and intercalated-motifs (IMs) are secondary, tetraplexed DNA structures abundant in non-coding regions of the genome, and recognised as potential therapeutic targets. Given their affinity for human proteins, G4 structures are investigated as potential decoys and aptamers. However, G4s tend to adopt different conformations depending on the exact environmental conditions, and often only one displays the specifically desired biological activity. The less intensively studied I-motifs are typically unstable at neutral pH, rendering their potential application in biological context challenging. We herein report on a photochemical method for “stapling” relevant tetraplexed-structures, to increase their stability, lock their topology and enhance their enzymatic resistance, while maintaining biological activity. The chemical structure and topology of the stapled Thrombin Binding Aptamer (TBA) model system was spectroscopically characterised and rationalised in silico. The method was expanded to other G4- and IM-prone sequences, hinting towards potential application of such stapled structures in a therapeutic context
Polarizability relaxation in protic ionic liquids: a comprehensive approach
No full textA molecular dynamic simulation has been performed to investigate the anisotropic polarizability relaxation for a series of alkylammonium nitrate protic ionic liquids. The main structural features along these systems were reviewed and compared with available data in literature. A new CPE parameter set for a series of alkylammonium ions has been proposed to calculate the atomic partial charges as well as the polarizability tensor in condensed phases. Polarizability relaxation takes place in the ~ 10 ps range due to the expected slow structural/reorientational relaxation in ionic liquids. From the set of polarizability TCFs we observe: i - a gradual depletion of reorientational motions of the ammonium cations with the increase cations size, ii – the total polarizability relaxation is dominated by the slow reorientational motions of the "N" "O" _"3" ^"-" . In frequency domain, there is a noticeable presence of a progression of librational bands in the light MeN denoting that in this system we find a dynamic characterized by fast and strong short-range pulses between H-bonded ionic species. The increase of the cations causes the depletion of the librational dynamics, and the H-bonding stretching mode emerges as a clear band composed by the reorientational motions of the cations and the interaction induced- mechanism in qualitative agreement with the corresponding experimental data. Beyond the traditional assignment of the bands arising from the cation-anion interaction we observe a compelling theoretical suggestion of pronounced librational dynamic in the low-frequency Raman spectra of the monomethylammonium nitrate
Enhancing Seafood Freshness Monitoring: Integrating Color Change of a Food-Safe On-Package Colorimetric Sensor with Mathematical Models, Microbiological, and Chemical Analyses
No full textA food-safe on-package label has been developed as a real-time spoilage indicator for fish fillets. This colorimetric sensor is sensitive to Total Volatile Base Nitrogen (TVB-N) levels, providing an accurate indication of fish freshness and spoilage. This study evaluates and predicts the shelf-life and effectiveness of an on-package colorimetric indicator. The sensor, using black rice (BR) dye with polyvinyl alcohol (PVOH), polyethylene glycol (PEG), and citric acid (CA) as binders and crosslinking agents, is applied to PET films. The food-safe pH indicator, prepared via lab-scale flexography printing, is durable in humid environments, making it suitable for practical packaging scenarios. The sensor visibly monitored fish spoilage at 4 ºC for 9 days. Quality assessment included tracking ΔRGB (total color difference), chemical (TVB-N, pH), and microbiological analyses. Results indicate that the fish samples are fresh up to 4 days of storage at 4ºC; the total viable count (TVC), Pseudomonas growth, TVB-N contents and pH reached: 5.2 (log CFU/ml), 4.31(log CFU/ml), 26.22 (mg N/100 gr sample) and 7.48, respectively. Integrating colorimetric sensor data with mathematical modeling can predict spoilage trends over time. Integrated system offers a smart approach to accurately predicting shelf-life, aiding in optimizing storage conditions, minimizing food waste, and delivering fresh, high-quality fish products to consumers
Identification of PLK1 as the Target of Tubocapsenolide A for the Activation of Colorectal Cancer Ferroptosis by PROTAC Technology
No full textDrug resistance seriously affects the treatment effect and survival rate of colorectal cancer (CRC) patients. The discovery of novel drugs and mechanisms is an important way to overcome drug resistance. Here, Tubocapsenolide A (TA), a major withanolide isolated from Tubocapsicum anomalum, significantly inhibited the growth of patient-derived organoids with oxaliplatin or 5-fluorouracil resistance and HCT116-/DLD-1-derived xenografts. Leveraging Proteolysis Targeting Chimera (PROTAC)-based target identification approach, PLK1 was identified as a direct target of TA. Mechanistically, PLK1 was first determined as a p53 cytoplasmic anchoring factor to prevent p53 from inducing ferroptosis in CRC. TA competitively inhibits the formation of PLK1-p53 heterodimers, promotes the nuclear translocation of p53, and then activates ferroptosis. Collectively, our study clarified the key role of PLK1 in p53-mediated ferroptosis for the first time and elucidated a novel mechanism of TA as a natural ferroptosis inducer in CRC treatment. The activation of the PLK1-p53-ferroptosis signaling axis may provide a brand-new strategy for the treatment of CRC
Novel Analytical Toolkit Concept for the Characterization and Development of Halogen Free Flame Retardants (HFFR): A case study with P and P-N based Flame Retardants.
No full textThis study presents a novel toolkit concept for the characterization and development of halogen-free flame-retardant (HFFR) specially based on P and P-N flame retardant systems, aimed at understanding and predicting the influence of flame-retardant additives in polymers especially polyolefins. The development of this toolkit concept is based on the existing research on flame-retardant mechanisms. From a comprehensive literature survey, we identified several key parameters that control the flammability of materials. This toolkit concept includes several analytical techniques to quantitatively measure these parameters.
The primary parameters influencing the flammability of polymer materials are found to be the surface ignition temperature, thermal degradation kinetics, total amount of volatiles produced during combustion, chemical composition of the volatiles, and the presence of flame retardants, particularly phosphorus and phosphorus-nitrogen-based derivatives (PFR), in the gas phase, condensed phase, or in both.
This paper presents our findings on surface ignition temperature (Tign) and kinetic degradation parameters such as Arrhenius activation energy (Ea) and frequency factor (A) from Thermo-Gravimetric Analysis (TGA)/SDTA) measurements. Additionally, we report the Total Volatile Organic Compounds (TVOC) produced during combustion, determined using Thermal Desorption (TD)/Gas Chromatography (GC)/Mass Spectrometry (MS) techniques, and the chemical composition of the volatiles identified through MS analysis of GC chromatograms for several model HFFR polypropylene (PP) formulations containing phosphorus (P) or phosphorus-nitrogen (P-N) based derivatives (PFR). The presence of flame retardants in the gas or condensed phase, and their activity in either phase or both, was determined using Inductively Coupled Plasma (ICP) and Surface Focussed Mass Spectrometer (SFMS).
In this report, the validity of the analytical results from this toolkit concept is also presented for several model formulations by comparing the analytical results with fire retarding properties of these model formulations with standard UL-94V fire tests. Applicability of this toolkit was demonstrated by investigating the influence for a proprietary additive, Paxymer® in these HFFR systems
Titania Nanocrystal/Reduced Graphene Oxide Hybrids: Flexible Humidity Sensors Tuned via Photocatalytic Reduction
No full textThe development of advanced relative humidity (r.h.) sensors holds immense potential for wearable applications where precise monitoring of environmental or physiological conditions is crucial. In this study, we explore the tunability of graphene oxide/reduced graphene oxide/titania nanocrystal (GO/rGO/TNC) hybrid films via photocatalytic reduction for resistive humidity sensing. First, we introduce a facile layer-by-layer spin-coating (LbL-SC) technique for the efficient fabrication of thin GO/TNC films (15-150 nm) on various substrates, using titania nanorods (TNRs) or nanoplates (TNPs). Second, we study the tunability of the films\u27 electrical, optical, and structural properties set by the photocatalytic activity of the TNCs upon UV exposure (254 nm), by varying the illumination time, TNC type, and film thickness. We show that the electrical conductance of the films dramatically increases in presence of TNCs, and that the GO/rGO and (GO/rGO)/TNC ratio can be adjusted, with prolonged UV treatment resulting in the degradation of GO/rGO with rates depending on the films\u27 composition and thickness. Third, we employ this method to tune the resistive sensing behavior of (GO/rGO)/TNC films on flexible substrates towards r.h. changes (ranges 35 – 85% and 1 – 80%). TNP-based films show superior humidity sensing performance to (GO/rGO)/TNR- and pristine GO/rGO films, with a sensitivity of up to 2.2 and response times down to 1 s. Depending on the film composition and the r.h. level, positive and negative responses are obtained. Gravimetric measurements reveal a similar mass uptake of water in all tested hybrid films, indicating that distinct resistive responses arise from differences in their chemical and electrical properties. Further, we demonstrate the use of these sensors for the detection of fluctuations in body-related humidity. Our findings highlight the potential of (GO/rGO)/TNC films and combinations thereof with tailored sensing characteristics as versatile platform for the design of advanced humidity sensors
Efficient generation of open multi-stage fragmentation mass spectral libraries
No full textUntargeted analysis based on high-resolution mass spectrometry is a key tool in clinical metabolomics, natural product discovery, and exposomics, with compound identification remaining the major bottleneck. Currently, MS2 fragmentation data and spectral library matching are the standard workflow for confident compound annotation. Multi-stage fragmentation (MSn) yields more profound insights into substructures, enabling validation of fragmentation pathways; however, the community lacks open MSn data for reference compounds. Here, we describe a high-throughput method for acquiring MSn trees and an automated workflow for extracting and building open MSn libraries. By applying this pipeline to 37,829 small molecules, we obtained MSn spectra for 30,008 unique compound structures within 23 days. This resource includes 2,350,646 MSn spectra (merged and individual) and can be leveraged for compound annotation based on library matching, including substructures and training of machine learning models on substructure-fragmentation patterns. The workflow, implemented in mzmine and Python scripts, is open-source and freely available
Modular Access to Functionalized Azetidines via Electrophilic Azetidinylation
No full textGeneral methods for the rapid and direct incorporation of unconventional ring motifs into core scaffolds are highly sought-after in medicinal chemistry. However, approaches enabling the direct attachment of privileged azetidine rings to the oft-encountered biorelevent nucleophiles remain elusive. Here, we report an electrophilic azetinylation protocol based on the underexplored reagents azetidinyl trichloroacetimidates, allowing for the “any-stage” installation of azetidine rings. More than 20 classes of nucleophiles can be readily azetidinylated, providing a diverse library of functionalized azetidines. The power of this method is further demonstrated by the simplified synthesis of multiple medicinally relevant structures and the facile access to azetidine analogues for bioactive compounds