Physicochemical Approach Research Articles

PACT - Prediction of amyloid cross-interaction by threading

Amyloid proteins are often associated with the onset of diseases, including Alzheimer’s, Parkinson’s and many others. However, there is a wide class of functional amyloids that are involved in physiological functions, e.g., formation of microbial biofilms or storage of hormones. Recent studies showed that an amyloid fibril could affect the aggregation of another protein, even from a different species. This may result in amplification or attenuation of the aggregation process. Insight into amyloid cross-interactions may be crucial for better understanding of amyloid diseases and the potential influence of microbial amyloids on human proteins. However, due to the demanding nature of the needed experiments, knowledge of such interactions is still limited. Here, we present PACT (Prediction of Amyloid Cross-interaction by Threading) - the computational method for the prediction of amyloid cross-interactions. The method is based on modeling of a heterogeneous fibril formed by two amyloidogenic peptides. The resulting structure is assessed by the structural statistical potential that approximates its plausibility and energetic stability. PACT was developed and first evaluated mostly on data collected in the AmyloGraph database of interacting amyloids and achieved high values of Area Under ROC (AUC=0.88) and F1 (0.82). Then, we applied our method to study the interactions of CsgA - a bacterial biofilm protein that was not used in our in-reference datasets, which is expressed in several bacterial species that inhabit the human intestines - with two human proteins. The study included alpha-synuclein, a human protein that is involved in Parkinson’s disease, and human islet amyloid polypeptide (hIAPP), which is involved in type 2 diabetes. In both cases, PACT predicted the appearance of cross-interactions. Importantly, the method indicated specific regions of the proteins, which were shown to play a central role in both interactions. We experimentally confirmed the novel results of the indicated CsgA fragments interacting with hIAPP based on the kinetic characteristics obtained with the ThT assay. PACT opens the possibility of high-throughput studies of amyloid interactions. Importantly, it can work with fairly long protein fragments, and as a purely physicochemical approach, it relies very little on scarce training data. The tool is available as a web server at https://pact.e-science.pl/pact/. The local version can be downloaded from https://github.com/KubaWojciechowski/PACT.

Exploration of interactions between L-aspartic acid and saccharides in aqueous medium at T = (293.15–313.15) K: Physicochemical and spectroscopic approach

In this study, we report the density, viscosity, taste behavior and UV– Vis spectrophotometry results of L-Aspartic acid (Asp) in aqueous solutions of L-arabinose and D-xylose over an integral composition regime (2.0 wt%, 2.5 wt%, and 3.0 wt%) at atmospheric pressure (P = 101 kPa) and at temperature ranges of (293.15, 298.15, 303.15, 308.15, and 313.15) K. The various densimetric and rheological parameters such as apparent molar volume (Vϕ), apparent molar volume at infinite dilution (Vϕ0), apparent molar isobaric expansion at infinite dilution (Eϕ0), Hepler’s constant (∂2VΦ0/∂T2)P, relative viscosity (ηr), viscosity coefficients (BJandAF), Gibbs free energy of activation of viscous flow of solvent and solute (Δμ1#,0andΔμ2#,0respectively), and corresponding change in enthalpy ΔH2#,0, entropy ΔS2#,0, apparent molar volume of transfer at infinite dilution (Vɸ,tr0) viscosity B-coefficients of transfer (BJ,tr), interaction coefficients (using the McMillan-Mayer theory), dB/dT and solvation number (Sn) have been calculated using the experimentally collected physical characteristic data (density and viscosity). Variation of these parameters with concentration and temperature were analyzed in the light of ion-ion, ion–dipole and ion-hydrophilic interactions between solute (L-Aspartic acid)-cosolute (L-arabinose and D-xylose) in aqueous medium. An effort has also been made to compare the taste behaviours of the amino acid in water and in an aqueous solution of saccharides, as the taste behaviour is separated into four basic taste qualities in distinct ranges. To access different common intermolecular interactions in the systems under consideration, the cosphere overlap model has also been used. A detailed evaluation of the results from the thermodynamic and physicochemical parameters shows that Asp acts as a structure builder when L-arabinose/D-xylose is present. The preservation of effective ionic interactions in the studied systems was further confirmed by UV spectral analysis.

Evaluation of the Acid-Base Status in Patients Admitted to the ICU Due to Severe COVID-19: Physicochemical versus Traditional Approaches.

Stewart's approach is known to have better diagnostic accuracy for the identification of metabolic acid-base disturbances compared to traditional methods based either on plasma bicarbonate concentration ([HCO3-]) and anion gap (AG) or on base excess/deficit (BE). This study aimed to identify metabolic acid-base disorders using either Stewart's or traditional approaches in critically ill COVID-19 patients admitted to the ICU, to recognize potential hidden acid-base metabolic abnormalities and to assess the prognostic value of these abnormalities for patient outcome. This was a single-center retrospective study, in which we collected data from patients with severe COVID-19 admitted to the ICU. Electronical files were used to retrieve data for arterial blood gases, serum electrolytes, and proteins and to derive [HCO3-], BE, anion gap (AG), AG adjusted for albumin (AGadj), strong ion difference, strong ion gap (SIG), and SIG corrected for water excess/deficit (SIGcorr). The acid-base status was evaluated in each patient using the BE, [HCO3-], and physicochemical approaches. We included 185 patients. The physicochemical approach detected more individuals with metabolic acid-base abnormalities than the BE and [HCO3-] approaches (p < 0.001), and at least one acid-base disorder was recognized in most patients. According to the physicochemical method, 170/185 patients (91.4%) had at least one disorder, as opposed to the number of patients identified using the BE 90/186 (48%) and HCO3 62/186 (33%) methods. Regarding the derived acid-base status variables, non-survivors had greater AGadj, (p = 0.013) and SIGcorr (p = 0.035) compared to survivors. The identification of hidden acid-base disturbances may provide a detailed understanding of the underlying conditions in patients and of the possible pathophysiological mechanisms implicated. The association of these acid-base abnormalities with mortality provides the opportunity to recognize patients at increased risk of death and support them accordingly.

Plasmonic metasurfaces of cellulose nanocrystal matrices with quadrants of aligned gold nanorods for photothermal anti-icing

Cellulose nanocrystals (CNCs) are intriguing as a matrix for plasmonic metasurfaces made of gold nanorods (GNRs) because of their distinctive properties, including renewability, biodegradability, non-toxicity, and low cost. Nevertheless, it is very difficult to precisely regulate the positioning and orientation of CNCs on the substrate in a consistent pattern. In this study, CNCs and GNRs, which exhibit tunable optical and anti-icing capabilities, are employed to manufacture a uniform plasmonic metasurface using a drop-casting technique. Two physical phenomena—(i) spontaneous and rapid self-dewetting and (ii) evaporation-induced self-assembly—are used to accomplish this. Additionally, we improve the CNC-GNR ink composition and determine the crucial coating parameters necessary to balance the two physical mechanisms in order to produce thin films without coffee rings. The final homogeneous CNC-GNR film has consistent annular ring patterns with plasmonic quadrant hues that are properly aligned, which enhances plasmonic photothermal effects. The CNC-GNR multi-array platform offers above-zero temperatures on a substrate that is subcooled below the freezing point. The current study presents a physicochemical approach for functional nanomaterial-based CNC control.

A Biomimetic Multiparametric Assay to Characterise Anti-Amyloid Drugs

Alzheimer’s disease (AD) is the most widespread form of senile dementia worldwide and represents a leading socioeconomic problem in healthcare. Although it is widely debated, the aggregation of the amyloid β peptide (Aβ) is linked to the onset and progression of this neurodegenerative disease. Molecules capable of interfering with specific steps in the fibrillation process remain of pharmacological interest. To identify such compounds, we have set up a small molecule screening process combining multiple experimental methods (UV and florescence spectrometry, ITC, and ATR-FTIR) to identify and characterise potential modulators of Aβ1-42 fibrillation through the description of the biochemical interactions (molecule–membrane Aβ peptide). Three known modulators, namely bexarotene, Chicago sky blue and indomethacin, have been evaluated through this process, and their modulation mechanism in the presence of a biomembrane has been described. Such a well-adapted physico-chemical approach to drug discovery proves to be an undeniable asset for the rapid characterisation of compounds of therapeutic interest for Alzheimer’s disease. This strategy could be adapted and transposed to search for modulators of other amyloids such as tau protein.

Temperature dependent micellar study of streptomycin sulfate in aqueous amino acid solutions: physicochemical approach

Temperature dependent micellar study of streptomycin sulfate in aqueous amino acid solutions: physicochemical approach

Correlation analysis of reactive oxygen and nitrogen species (RONS) components in plasma activated water (PAW) and its inactivation of Bacillus cereus endospore

Plasma activated water (PAW), a physicochemical approach that can efficiently enable the inactivation effect of Bacillus cereus endospores, is receiving numerous attentions in food and other areas. However, the potential RONS featuring PAW that inactivates bacteria is an open issue. Here, we for the first time thoroughly clarified the functioning chemicals on antimicrobial ability in PAW by adding each corresponding scavenger at an optimized dose, including superoxide anion (O2−), singlet oxygen (1O2), hydroxyl radical (OH), hydrogen peroxide (H2O2), nitrite ions (NO2−), nitric oxide (NO) and peroxynitrite (ONOOH). An overall reduction of 1.74 log CFU/mL is determined by the sporicidal effects of PAW; however, when adding their corresponding scavengers, the effect was attenuated to different extents. The internal correlations are constructed using Spearman analysis based on the inactivation of endospores for determining their specific contributions in such a complex PAW system and corresponding effective factors are calculated. The Spearman coefficients of NO2−, O2−, H2O2, and NO were 0.476, 0.405, 0.168, and 0.143, revealing that the log CFU/mL reduction of B. cereus endospore was positively proportional to the contents of NO2−, O2−, H2O2, and NO. This study addresses the fundamental issues related to the chemicals in PAW and may initiate wide interest in PAW in physiochemistry and biology.

Physicochemical Mechanics and Nonequilibrium Chemical Thermodynamics.

Equilibrium thermodynamics answers the question, "by how much?" Nonequilibrium thermodynamics answers the question "how fast?" The physicochemical mechanics approach presented in this article answers both of these questions. It also gives equilibrium laws and expressions for all major transport coefficients and their relations, which was previously impossible. For example, Onsager's reciprocal relations only tell us that symmetric transport coefficients are equal, and even for these, the value is often not known. Our new approach, applicable to non-isolated systems, leads to a new formulation of the second law of thermodynamics and agrees with entropy increase in spontaneous processes for isolated systems. Instead of entropy, it is based on a modified Lagrangian formulation which always increases during system evolution, even in the presence of external fields. This article will present numerous examples of physicochemical mechanics can be applied to various transport processes and their equilibriums, including thermodiffusion and different surface processes. It has been proven that the efficiency of a transport process with an actual steady-state flux (as opposed to a reversible process near equilibrium) is 50%. Finally, an analogy between physicochemical mechanics and some social processes is mentioned.

Simulation of Hybrid All-Solid-State Battery Performance Under Consideration of Ceramic-Polymer Phase Boundaries Using a Physicochemical Modelling Approach

With the growing interest in all-solid-state battery (ASSB) technology for high-energy and high-power applications, the electrochemical performance of cell components and production-related characteristics must be improved to achieve reliable and cost-effective scale-up of laboratory cell concepts [1]. Combining inorganic ceramic and polymer solid electrolytes (SEs) serves to tune the ionic transport and the mechanical properties of composite cathodes [2, 3]. A polymer electrolyte share in the composite cathode is expected to improve the mechanical contact between the cathode active material (CAM) and the SE, resulting in facilitated charge transfer and improved cell performance. Furthermore, polymer SEs serve to overcome the challenges of co-sintering dense composites of CAM and inorganic SE [4, 5].In hybrid cell concepts with polymer- and inorganic ceramic SE, the ionic transport path crosses a ceramic-polymer phase boundary, which leads to additional polarization through charge transfer and ohmic resistance. State-of-the-art literature discusses the influence of ceramic particles in polymer electrolytes, but falls short on the impact of ceramic-polymer phase boundaries on the total cell performance of ASSBs [6, 7, 8].To allow for the simulation of hybrid full cells, a pseudo-two-dimensional (p2D) physicochemical model is introduced within this work. The model is based on the Newman approach, modified with a description for the ceramic-polymer phase boundary [9]. In equilibrium state, the potential drop across the ceramic-polymer boundary was modeled with the Donnan-potential condition as recently proposed by Kim et al. [10]. Under current flow, additional polarization occurs at the interface due to electrochemical charge transfer, which was modeled by the Butler-Volmer equation, and ohmic contact resistance. The conservation of mass and charge over the phase boundary was secured with a current, flux, and a potential boundary condition. A model cell was defined (see figure 1) and parametrized using material-specific values for the ionic and electronic transport characteristics as well as the interface and charge transfer properties. Since the focus of this study was on the ceramic-polymer phase boundary, ideal plating and stripping behavior at the Li-metal anode were assumed neglecting irregular lithium deposition, e.g., lithium dendrite formation. As separator material, the well-known ceramic LLZO SE was modeled. A composite cathode with NMC-622 as CAM and PEO/LiTFSI as polymer electrolyte was assumed. The lower part of figure 1 shows the reduced 1D-model geometry and the ion transport mechanisms in each model domain.The established physicochemical model was applied to identify performance-limiting effects in hybrid ASSBs to conclude on cell designs achieving high energy and power densities.To quantify and localize the polarization contributions in each domain, arising from SE ionic conductivity, diffusion or charge-transfer processes, as well as phase boundaries, the method proposed by Nyman et al. was used [11]. Figure 2 a) shows the results of polarization analysis when simulating a 0.1C charge, while figure 2 b) depicts the results for a 1C charge. Diffusion limitation in the polymer electrolyte led to high concentration gradients in the polymer-phase of the composite cathode, resulting in high diffusion polarization at elevated charging rates as shown in figure 2 b). This determined a critical current density at cell level, which was caused by large Li-ion concentration gradients and a possible depletion of Li-ions near the ceramic separator.The overall cell polarization was further enhanced by the ceramic-polymer phase boundary. For the contact case of LLZO versus PEO/LiTFSI considered here, the equilibrium potential between the phases was calculated according to the theory of Donnan to 31 mV.Since a wide range of values for the contact resistance at the ceramic-polymer interface is reported in the literature [6, 7], ohmic polarization could be important and was therefore evaluated as a function of different contact resistances. A critical contact resistance was determined to achieve the requirements for future battery technologies regarding energy and power density. Figure 1

Modeling ultra-high dose rate electron and proton FLASH effect with the physicochemical approach

Objective. A physicochemical model built on the radiochemical kinetic theory was recently proposed in (Labarbe et al ) to explain the FLASH effect. We performed extensive simulations to scrutinize its applicability for oxygen depletion studies and FLASH-related experiments involving both proton and electron beams. Approach. Using the dose and beam delivery parameters for each FLASH experiment, we numerically solved the radiochemical rate equations comprised of a set of coupled nonlinear ordinary differential equations to obtain the area under the curve (AUC) of radical concentrations. Main results. The modeled differences in AUC induced by ultra-high dose rates appeared to correlate well with the FLASH effect. (i) For the whole brain irradiation of mice performed in (Montay-Gruel et al ), the threshold dose rate values for memory preservation coincided with those at which AUC started to decrease much less rapidly. (ii) For the proton pencil beam scanning FLASH of (Cunningham et al ), we found linear correlations between radicals’ AUC and the biological endpoints: TGF-β1, leg contracture and plasma level of cytokine IL-6. (iii) Compatible with the findings of the proton FLASH experiment in (Kim et al ), we found that radicals’ AUC at the entrance and mid-Spread-Out Bragg peak regions were highly similar. In addition, our model also predicted ratios of oxygen depletion G-values between normal and UHDR irradiation similar to those observed in (Cao et al ) and (El Khatib et al ). Significance. Collectively, our results suggest that the normal tissue sparing conferred by UHDR irradiation may be due to the lower degree of exposure to peroxyl and superoxide radicals. We also found that the differential effect of dose rate on the radicals’ AUC was less pronounced at lower initial oxygen levels, a trait that appears to align with the FLASH differential effect on normal versus tumor tissues.

Physicochemical Approach to Pour Point Depressant Treatment of Waxy Crudes

A physicochemical approach was taken to show wax-based and crude oil-based differences between three waxy crudes (Amenam, Norne, and Varandey), that had similar amounts of wax according to DSC crystallizable areas, that were responsible for very different responses to pour point depressant additive treatments. Varandey crude oil was the most difficult to treat, and the effectiveness of the additives decreased with time when the oil had been aged for 2 years prior to treating with the additives. Detailed compositional analysis of these three crude oils, and their waxes, showed that Varandey contains the highest concentration of longer n-paraffins, significantly more total n-paraffins, a higher wax appearance temperature, the highest amount of wax that can be centrifuged at ambient temperature, a bimodal distribution of crystallizable waxes by DSC, more saturates in the heavy ends by the Saturates, Aromatics, Resins-Asphaltene Determinator, a very high amount of Waxphaltene Determinator Waxy B (–24 °C methyl ethyl ketone precipitated waxes that do not dissolve in heptane at that temperature but melt at 60 °C in heptane) and very little asphaltenes that do not flocculate. These additional characterization methods, including the wax appearance temperature, show that the amount of wax by DSC is not discriminating for some crude oils. Microscopy of Varandey showed large fractal crystalline domains that were different from Amenam, which showed classic large macrocrystalline needle-like crystals, or Norne that had a gelled network with much smaller needle-like crystals. Norne is less responsive to additive treatment than Amenam despite having significantly less n-paraffins, Waxphaltene Determinator Waxy B waxes, and asphaltenes. Simulated distillation shows that Norne is the heaviest oil and has the highest amount of isomeric material in the C24–C34 range and a higher temperature wax appearance temperature. Furthermore, its asphaltenes flocculated with the addition of isooctane at 60 °C, whereas the asphaltenes did not flocculate in Amenam. The higher amount of isomeric material by GCMS and the much smaller needle-like crystallites suggest that Norne wax is more microcrystalline in nature. Centrifuging Varandey waxes and doping them into Amenam and Norne resulted in the doped crude oils having a bimodal DSC profile with a higher wax appearance temperature. The presence of Varandey wax caused the oils to be significantly less responsive to pour point additive treatments. Overall, for these relatively similar crude oils, it is shown that the nature of the highest carbon number waxes, the wax appearance temperature, and the amount of the least soluble waxes are significantly more important than the crude oil composition when treating with additives since they will dictate the temperature at which n-paraffins first self-associate leading to crystal nucleation.

Influence of dispersant and surfactant added graphene oxide nanoparticles on Mahua biodiesel blend: stability and physicochemical properties approach

Influence of dispersant and surfactant added graphene oxide nanoparticles on Mahua biodiesel blend: stability and physicochemical properties approach

Exploring Inclusion Complex of an Antithyroid Drug (PTU) with α-Cyclodextrin for Innovative Applications by Physicochemical Approach Optimized by Molecular Docking

Herein, we aim to form the inclusion complex (IC) of an antithyroid drug 6-propyl-2-thiouracil (PTU) with α-cyclodextrin (α-CD) and to analyse its aqueous solubility, photostability, binding with Calf thymus DNA (CT-DNA), antibacterial and cytotoxic activities. The PTU-α-CD complex was synthesized by following the co-precipitation method with a molar ratio of 1:1. The formed complex was characterized by employing several spectroscopic techniques such as nuclear magnetic resonance (1H NMR), fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA), powder XRD and scanning electron microscopy (SEM) indicated the successful encapsulation of drug PTU into the nano cage of α-CD. The enhancement of thermal stability of PTU after complexation was shown by TGA and DSC analysis. Job’s plot confirmed the 1:1 M ratio of guest (PTU) and host (α-CD) during the formation of IC and the molecular association constant as predicted between PTU and α-CD using UV–vis titration method was found to be 3297.57 ± 0.15 M−1. The most desired orientation of the PTU molecule within the non-polar binding pocket of α-CD cavity was speculated by molecular modelling study. The PTU-α-CD complex showed better in vitro antimicrobial activity results as compared to pure drug PTU. The aqueous solubility and photostability of PTU were greatly improved owing to the formation of the PTU-α-CD complex as shown using UV–vis spectroscopy. The PTU-α-CD complex (IC50 = 2.12 µM) also displayed noteworthy in vitro cytotoxic activity than pure PTU (IC50 = 6.44 µM) towards human kidney cancer cell line (ACHN) whereas (IC50 = 3.63 µM) and (IC50 = 2.09 µM) for PTU-α-CD and drug respectively in a normal kidney cell line (HEK-293). This research also predicts the release of PTU in presence of CT-DNA without any chemical alteration. Finally, these outcomes disclose that the complexation of PTU with α-CD could enhance the stability of PTU and display various applications associated with it.

Interactions of Surfactants with Biomimetic Membranes-2. Generation of Electric Potential with Non-Ionic Surfactants.

It is known that noncharged surfactants lead to electric effects that interact with biomimetic membranes made of nitrocellulose filters, which are impregnated with fatty acid esters. At a surfactant concentration as low as 64 micrometers in one of the solutions, they lead to the transient formation of transmembrane electric potential. Maximum changes of this potential are proportional to the log of noncharged surfactant concentrations when it changes by three orders of magnitude. We explain this new and nontrivial effect in terms of an earlier suggested physicochemical mechanics approach and noncharged surfactants transient changes induced by membrane permeability for inorganic ions. It could be used to imitate the interactions of non-ionic drugs with biological membranes. The effect may also be used in determining the concentration of these surfactants and other non-ionic chemicals of concern, such as pharmaceuticals and personal care products.

The variability influence of physicochemical parameters on macroinvertebrate assemblages in the Rhumel and Endja rivers, Algeria

Abstract. Kherief-Nacereddine S, Djeddi H, Nail-Yasmine B, Boukeria S, Benmakhlouf Z, Mehennaoui-Afri FZ. 2023. The variability influence of physicochemical parameters on macroinvertebrate assemblages in the Rhumel and Endja rivers, Algeria. Biodiversitas 24: 539-550. Water resources are the most essential resource in the development of the various sectors of a country's economy. In Algeria, a country with a semi-arid climate, the supply of drinking and industrial water is mainly provided by surface water. Currently, the water supply for industrial uses is threatened by the problems of anthropogenic pollution (e.g., urban discharges, industrial and agricultural activities, etc.). The objective of this work is to assess the variability influence of water physicochemical parameters on macroinvertebrate communities in the Rhumel and Endja rivers in Algeria which supply the Beni Haroun. In each river, two observation stations were established located upstream and downstream, totaling four stations (Rhumel: (Rh1 and Rh2) and Endja: En 1 and En 2). Physicochemical parameters of water were measured, and biological parameters of benthic macroinvertebrate assemblages were calculated. The physicochemical approach put highlights the monthly changes in water quality along the two rivers in relation to urban, agricultural, and industrial discharges and as a response to seasonal variations in water level. The difference in taxonomic richness corresponded to environmental conditions of stations appearing more or less stable and highlighting a gradient of the stress on organisms. The results showed that there were 2071 individuals of macroinvertebrates recorded, belonging to 19 families and 10 orders. The individual number of this macrofauna consisted of 75.20% insects, 12.50% worms, and 12.30% mollusks, with the most abundant families across all stations being Chironomidae and Baetidae. The spatiotemporal variability of benthic macroinvertebrate assemblages in the two rivers indicated that summer recorded the highest abundance of all samples. The highest number of macroinvertebrate individuals was recorded at Rhumel stations. The elements indicating high pollution were SO4, PO4- and NO2- with the highest values recorded during the summer season for the four stations. Higher pollution was observed at the Endja river. The findings of this study imply that the waters of two rivers are unsuitable for use even for irrigation purposes.

Physicochemical approach for the modification of medical nanoporous carbon sorbents

Physicochemical approach for the modification of medical nanoporous carbon sorbents

An electrolyte induced thermodynamic study of quercetin and Tween 20: A physico-chemical approach for formulation development

The present study represents the thermodynamic interactions between the non-ionic surfactant Tween 20 and the well-known flavonoid quercetin. The conductivity experiments were conducted at five different temperatures (20 °C, 25 °C, 30 °C, 35 °C and 40 °C) using various quercetin concentrations (1 mM, 2 mM and 3 mM) in 70 % v/v ethanol as a solvent. To overcome the non-conducting behavior of non-ionic surfactant Tween 20, as an electrolyte, sodium chloride solution (1 % w/v) was added. The critical micelle concentration (CMC) and XCMC values were calculated as a function of temperature using the specific conductivity experiments. In addition, a number of thermodynamic parameters, including change in Gibbs free energy of micellization (ΔGom), change in enthalpy (ΔHom), and entropy (ΔSom), have been estimated. Overall, the effects of quercetin on Tween 20′s micellization behaviour have been studied.

Interaction between carbon dots from folic acid and their cellular receptor: a qualitative physicochemical approach.

According to the World Health Organization, the number of cancers (all cancers, both sexes, all ages and worldwide) in 2020 reached a total of 19 292 789 new cases leading to 9 958 133 deaths during the same period. Many cancers could be cured if detected early. Preventing cancer and detecting it early are two essential strategies for controlling this pathology. For this purpose, several strategies have been described for imaging cancer cells. One of them is based on the use of carbon nanoparticles called carbon dots, tools of physical chemistry. The literature describes that cancer cells can be imaged using carbon dots obtained from folic acid and that the in cellulo observed photoluminescence probably results from the interaction of these nanoparticles with the folic acid-receptor, a cell surface protein overexpressed in many malignant cells. However, this interaction has never been directly demonstrated yet. We investigated it, for the first time, using (i) freshly synthesized and fully characterized carbon dots, (ii) folate binding protein, a folic acid-receptor model protein and (iii) fluorescence spectroscopy and isothermal titration calorimetry, two powerful methods for detecting molecular interactions. Our results even highlight a selective interaction between these carbon made nano-objects and their biological target.

Thermal and Mechanical Characterization of Yarn Samples from Flemish Tapestry of the Sixteenth Century

We propose a physico-chemical approach for theharacterization of the conservation condition of yarns from a Flemish tapestry of the sixteenth century. The aging effect on the yarns' performance was evaluated by comparison with commercial materials. Water uptake experiments highlighted the aptitude of yarns toward water sorption and their increased hydrophilicity upon aging. Thermogravimetric analysis can be considered a fast approach for the fiber identification and assessment on the material life-time. The dynamic mechanical analysis provided direct evidence on the yarns, conservation state and their performance under different mechanical stresses. The proposed characterization path can be relevant for stating the condition of the tapestry and for designing a conservation protocol for the preservation of the artwork.

The growth mechanism of diffused multilayer between electroplated nickel coating and nickel-aluminum bronze alloy

• 1. The calculated results of Fick’s second law prove the relationship: D Ni > D Cu > D Al . • 2. The larger D Ni and D Cu than D Al cause the preferential formation of Ni-Cu layer. • 3. The physicochemical approach is used to explain the ternary interdiffusion process. • 4. The formation of Ni-Al-Cu layer is at the expense of the depletion of Ni-Cu layer. The Ni-rich surface alloying modification has been implemented to enhance the corrosion resistance of nickel-aluminum bronze (NAB) alloy used in the marine environment, while the growth behavior of the Ni-rich diffused multilayer is still unclear. Herein, the theoretical analysis and morphological observation were applied to disclose the growth mechanism of the diffused multilayer, the results manifested that the diffusion coefficients of Ni and Cu were higher than that of Al, leading to the preferential interdiffusion process of Ni and Cu to generate the Ni-Cu solid solution gradient layer at the interface of the diffusion couple. With extending the heat treatment time, the Al diffused into the Ni-Cu layer to form the Ni-Al-Cu intermetallic layer between the Ni-Cu layer and NAB matrix, and the formation of Ni-Al-Cu layer was at the expense of the depletion of Ni-Cu layer.