Absorption Changes Research Articles

Full Conjugation in a Polymer with Non‐conjugated Piperazine‐2,5‐dione Units via Energy‐minimized Lactam‐to‐Lactim Tautomerization Enables Water‐gated Transistor Fluoride Sensors

AbstractPiperazine‐2,5‐dione (glycine anhydride, GA) has recently emerged as a valuable precursor for high‐performance π‐conjugated polymer semiconductors in organic electronics. We utilized GA to design a novel bisindolin‐dihydropiperazine (IDHP)‐based conjugated polymer, PIDHPTT, for aqueous chemical sensing. In the isatin‐flanked monomer, GA exists as a non‐conjugated lactam (DHP‐NH) but converts to a conjugated lactim (DHP‐OH) form within the polymer. Density functional theory (DFT) calculations show that this conversion is driven by energy minimization via extended π‐conjugation. Neighboring DHP units in the lactim form facilitate this process through π‐bridges, demonstrating a vinylogous effect, which has previously only been observed in small molecules. This is the first study to report such a long‐range vinylogous effect in a polymer due to the collective synergy of numerous functional groups. The OH groups in the lactim DHP interact more strongly with fluoride ions than other halides. PIDHPTT exhibits significant changes in optical absorption, electrochemical impedance, and charge transport in response to fluoride ions, which differ from responses to other halides. A water‐gated organic field‐effect transistor based on PIDHPTT shows excellent sensitivity and selectivity for fluoride ions, demonstrating the potential of this polymer design for chemical sensing applications.

Compact Time-Domain Diffuse Optics System Based on CMOS Technologies for Fast Acquisitions of Heartbeat-Induced Absorption Changes

Compact Time-Domain Diffuse Optics System Based on CMOS Technologies for Fast Acquisitions of Heartbeat-Induced Absorption Changes

Covalent organic framework-assisted solar energy storage in long-lived organic radicals for enzyme-free colorimetric detection of xanthine

Xanthine monitoring is meaningful for both human health and food industrial, but rapid, cost-saving and natural enzyme-free detection of xanthine is still a big challenge. Herein, a new covalent organic framework (FPPy-TSC COF) with unique photoelectric properties is developed for rapid, enzyme-free and sensitive colorimetric detection of xanthine in complex real samples. In the presence of xanthine, FPPy-TSC COF interacts with xanthine through hydrogen bonds, and the electrons generated by FPPy-TSC COF under light irradiation can be transferred to xanthine with the result of storing solar energy in the form of long-lived organic radicals. Then the electrons stored in xanthine gradually reduce dissolved oxygen to oxygen radicals under dark conditions, which subsequently catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxidized products (oxTMB). Based on the characteristic absorption and color changes, xanthine can be detected under dark condition by naked eyes, spectrometry and smartphone with the detection limit low to 3.23μM (3σ/K). Moreover, xanthine contents in serum and pork samples can be accurately detected with the recoveries ranging from 95.28 to 107.34%. This work not only proposes a novel enzyme-free detection system for xanthine, but also broadens the sensing application of COF nanozymes under dark condition.

Full Conjugation in a Polymer with Non-conjugated Piperazine-2,5-dione Units via Energy-minimized Lactam-to-Lactim Tautomerization Enables Water-gated Transistor Fluoride Sensors.

Piperazine-2,5-dione (glycine anhydride, GA) has recently emerged as a valuable precursor for high-performance π-conjugated polymer semiconductors in organic electronics. We utilized GA to design a novel bisindolin-dihydropiperazine (IDHP)-based conjugated polymer, PIDHPTT, for aqueous chemical sensing. In the isatin-flanked monomer, GA exists as a non-conjugated lactam (DHP-NH) but converts to a conjugated lactim (DHP-OH) form within the polymer. Density functional theory (DFT) calculations show that this conversion is driven by energy minimization via extended π-conjugation. Neighboring DHP units in the lactim form facilitate this process through π-bridges, demonstrating a vinylogous effect, which has previously only been observed in small molecules. This is the first study to report such a long-range vinylogous effect in a polymer due to the collective synergy of numerous functional groups. The OH groups in the lactim DHP interact more strongly with fluoride ions than other halides. PIDHPTT exhibits significant changes in optical absorption, electrochemical impedance, and charge transport in response to fluoride ions, which differ from responses to other halides. A water-gated organic field-effect transistor based on PIDHPTT shows excellent sensitivity and selectivity for fluoride ions, demonstrating the potential of this polymer design for chemical sensing applications.

PBPK modelling for the evaluation of drug-drug interaction between meropenem and valproic acid.

The present study aimed to quantitatively investigate the potential drug-drug interaction (DDI) mechanism between meropenem (MEPM) and valproic acid (VPA). In the present study, we firstly developed a physiologically based pharmacokinetic (PBPK) model of MEPM and VPA. The verified PBPK model was then used to quantitatively investigate the potential DDI between MEPM and VPA. The effect of genetic polymorphisms of acylpeptide hydrolase (APEH) on DDI was also evaluated. In our simulation, the plasma concentration of hydrolysate of VPAG decreased to 63% when combined with MEPM. Total plasma concentration of VPA before carbapenem use was 53.61 mg/L, whereas it was 45.42 mg/L during carbapenem use. The inhibition of hydrolysis of VPAG by MEPM alone could not result in a rapid and substantial decrease in the plasma concentration of VPA. Parameter sensitivity analysis showed that the changes of absorption played an important role in the maximum plasma concentration (Cmax) of VPA, whereas area under the plasma concentration-time profile (AUC) was more susceptible to elimination changes. In addition, a decrease in APEH activity had little impact on the plasma pharmacokinetics of VPA. The DDI between MEPM and VPA might be a comprehensive result of multiple factors. On the basis of our simulation, interval medication of MEPM injection and VPA immediate release tablet at 4-6h timed interval was recommended, or intravenous administration of VPA solution was preferred when combination regimen was necessary in a clinical setting.

A C3‐Symmetric Structurally Twisted Molecular Architecture: Mechano‐/Fluorochromic Behavior and Selective Multiphase Detection of Pd(II)

AbstractTriaminoguanidinium (TG)‐based C3‐symmetric‐like molecular architectures with diverse donors and acceptors are well established as organic molecular materials for promising stimuli‐responsive and metal sensing‐based applications. However, the mechanofluorochromic (MFC) response was unremarkable upon applying external mechanical stress. Even though some show MFC features, there was no optical shift under ambient light. In this paper, we developed a novel C3‐symmetric molecule, TAC3, containing the TG core linked with conformationally twisted thiophene‐linked anthracenyl terminals. Three conformationally deformed hands in TAC3 respond against external mechanical stimuli with a redshifted absorption and emission, easily detectable through the naked eye. Although MFC features were reported before for such C3‐symmetric molecules, the change in absorbance was not identified. In addition, TAC3 could selectively detect Pd2+ through extreme emission quenching (green to black). The mechanochromism and sensing outcomes are elucidated by the experimental and theoretical support. Compared to the previous reports, the notable 2 : 3 (metal: ligand) binding due to geometric restriction creating a specific pocket size for Pd+2 is unusual for this system. The onsite application on Pd2+ detection and measurable MFC features are demonstrated to validate the potential of this C3‐symmetric molecule in advanced optoelectronic applications such as security writing and Pd2+ ion detection.

Antioxidants Recognition Colorimetric Sensor Array Based on Multicolor System

ABSTRACTA colorimetric sensor array with three identification signals has been developed to visually recognize five antioxidants based on CuFe Prussian blue analogs nanocubes (CuFe PBA NCs) and 3,3′,5,5′‐tetramethylbenzidine (TMB). The CuFe PBA NCs can oxidize TMB to produce three ultraviolet–visible (UV–Vis) absorption peaks at different wavelengths (370, 450, and 650 nm). Depending on the different reduction capacity of dopamine, cysteine, ascorbic acid, glutathione, and melatonin, the redox process can be inhibited to varying degrees, resulting in different changes in the signal generation of three identification elements. And in the presence of different antioxidants, the color of the solution also changes in different degrees. Five antioxidants (20 μM) can be identified by this colorimetric sensor array, and the identification accuracy was 100% for 40 unknown antioxidants. In addition, these antioxidants can also be quantified based on the regression equation between the concentration of the antioxidants and the absorbance change. The correlation coefficient is greater than 0.990, and the detection limit is less than 3.5 μM.

High-temperature solar energy absorption enhancement of mixed-phase core–shell spherical Al-based composite particles

This study focuses on the development of heat transfer/thermal energy storage particles for direct irradiation solid particle solar receivers to improve the efficiency by enhancing solar absorption, thermal stability, thermal storage property, and mechanical strength. A novel dry-mix extrusion technique was adopted to synthesize Al-based core–shell composite particles. The research shows that particles coated with 5.5 wt% mixed-phase metallic compounds maintain over 90 % solar absorptivity after 300 h at 1200°C, 600-1200°C thermal cycling, and wear tests, with an absorptivity change negligible (±2.20 %) and a mass loss of less than 0.053 g. The cost of the particles is below 1.5€/kg with good flowability, compressive strength up to 398.6 MPa, and an energy density as high as 2675.3 kJ/(m3·K). Monte-Carlo finite element numerical results found that the absorption efficiency of a composite particle curtain with a thickness of 0.02 m and a volume fraction of 0.05 increased by 169.6 % over the original ones. The particles can operate for extended periods at higher temperatures or harsh conditions to improve energy conversion efficiency, extend service life, and reduce maintenance requirements. It demonstrates the potential application value in the field of thermal energy absorption and storage, providing highly promising candidates for future high-temperature solar thermal applications.

In vivo detection of spectral reflectance changes associated with regulated heat dissipation mechanisms complements fluorescence quantum efficiency in early stress diagnosis.

Early stress detection of crops requires a thorough understanding of the signals showing the very first symptoms of the alterations in the photosynthetic light reactions. Detection of the activation of the regulated heat dissipation mechanism is crucial to complement passively induced fluorescence to resolve ambuiguities in energy partitioning. Using leaf spectroscopy, we evaluated the capability of pigment spectral unmixing to calculate the fluorescence quantum efficiency (FQE) and simultaneously retrieve fast absorption changes in a drought and nitrogen deficiency experiment with tomato. In addition, active fluorescence measurements and pigment analyses of xanthophylls, carotenes and chlorophylls were conducted. We observed notable responses in noninvasive proximal sensing-retrieved FQE values under stress, but as expected, these alone were not enough to identify the constraints in photosynthetic efficiency. Reflectance-based detection of the 535-nm peak absorption change was able to complement FQE and indicate the activation of regulated heat dissipation for both stress treatments under growing light conditions. However, further complexity in the light harvesting energy regulation needs to be accounted for when considering additional light stress. Our results underscore the potential of complementary in vivo quantitative spectroscopy-based products in the early and nondestructive stress diagnosis of plants, marking the path for further applications.

Clinical significance of determining the level of citrulline in children who have undergone intestinal resection during the neonatal period

Citrulline is an amino acid that is not found in protein and does not enter the body through food, enteral or parenteral nutrition. It is instead synthesized exclusively by enterocytes. Therefore, citrulline concentrations in the blood can reflect the process of biosynthesis in the intestines and are directly related to changes in the function of these cells.Purpose. The aim of the study was to assess citrulline levels in children who had undergone intestinal resection during the neonatal period.Material and methods. The study included 22 children with short bowel syndrome, diagnosed by a doctor (main group; average age 3.7 months). We also included 20 children who had undergone surgery to remove less than 50% of their intestine but did not have short bowel syndrome (comparison group; average age 3 months 1 day). The control group consisted of 23 healthy children who had never had surgery on their gastrointestinal tract and did not have any congenital malformations or clinical signs of enteropathy (average age 5 months 3 days). High performance liquid chromatography-mass spectrometry (HPLC-MS) was used to measure the level of citrulline.Results. The average level of citrulline in the blood of children in the main group was 18 μmol/l (95% CI 10–22.8), in the comparison group – 17.5 μmol/l (95% CI 16–21), in the control group – 26 μmol/l (95% CI 22–3). Citrulline levels in patients who underwent surgery in the neonatal period were significantly different from those of children in the control group There were no differences in the content of citrulline between the main and comparison groups, depending on whether the colon was preserved or not and whether the ileocecal valve was present (p>0.05).Conclusion. An increase in citrulline level in the blood of children receiving therapy with a glucagon-like peptide-2 analog indicates the possibility of using this marker to monitor changes in intestinal absorption associated with physiological or pharmacological adaptation of the intestine.

Tracking a Homeopathic Complex Formulation in the Watercourses of a Fire-Damaged State Park in Brazil.

In 2020, a 26,849-ha state park in Mato Grosso do Sul state, Brazil, had 30% of its area damaged by fire. A homeopathic complex formulation was applied at strategic point locations in the park's springs or watercourses, aiming to mitigate the fire damage to the flora and fauna as quickly as possible. The duration of the homeopathic signal at each point was assessed using an established solvatochromic dye technique. To evaluate the timing and the nature of the signal at each of nine point locations. We could thus identify the presence of any signal variations due to specified environmental features within the park. Water samples were harvested from each intervention point at different times, filtered, frozen, and sent to the laboratory, where they were prepared to 1cH using filtered 30% ethanol. Methylene violet was chosen among six dyes since it was found in preliminary tests that it could trace the homeopathic complex used. In addition to simple sample testing, samples were submitted to a static and unidirectional magnetic field of 2400 Gauss (240 mT) for 15 minutes immediately before reading, which enhanced the method's sensitivity. One-way analysis of variance/Tukey test was used to identify dye absorbance changes following the analysis of water samples from the watercourse system. A correlation matrix and the Spearman r test were employed to evaluate any correlation between tracking and the pre-existing anthropic interventions at harvesting points. In all cases, α = 0.05. Four tracking patterns using the sample magnetization process were observed in relation to water samples and their effect on methylene violet solutions: no response (P2, P4), early transitory response (P5, P6, P8), late response (P1, P9), and constant response (P3, P7). P2 and P4, which could not be tracked, were correlated with permanent local anthropic disturbance. Methylene violet was the best dye to track the homeopathic complex prepared specifically for this case. Tracking was facilitated by prior magnetic treatment of samples, but anthropic disturbances to the environment seem to interfere with it.

High Temperature Effects on Global Heritage Stone Resources: A Systematic Review

Throughout history, natural stone has been a crucial building material due to its strength, durability, and aesthetic qualities. Today, it continues to be a valuable resource, representing both a cultural heritage asset and a significant economic material. However, the increasing frequency of heat waves and fires driven by climate change poses a growing threat to stone building materials. This paper reviews the scientific attention given to the effects of high temperatures on Global Heritage Stone Resources (GHSRs), an international classification designed to enhance the recognition and status of building stones. Through a systematic SCOPUS search with refined filtering criteria, the study aims to quantify the existing research on these heritage stones. The search applied the standardized lithotype terms from GHSR publications to ensure consistency, followed by the exclusion of irrelevant terms when identified. Additionally, a relevance filter was applied to restrict the number of articles per lithotype and ensure that only the most pertinent studies were considered. Key findings from the literature reveal that exposure to high temperatures (ranging from 200 °C to 900 °C) significantly affected the studied GHSRs, leading to thermal micro-fissuring, increased porosity, and changes in water absorption, which compromise the mechanical properties of the stones. Moreover, these conditions can result in irreversible chemical transformations, exacerbating the deterioration of cultural heritage assets. The study emphasizes the critical need for research to better understand how these stone materials behave when exposed to high temperatures. It also provides a relevant framework for future investigations aimed at predicting and mitigating the effects of external threats such as fires.

Ultra-broadband absorber and perfect thermal emitter for high-efficiency solar energy absorption and conversion

This study proposes a pyramid-shaped solar absorber designed with multi-layered Ti-SiO2 ring stacked. The structure achieves an average absorption efficiency of 98.03 % over the range of 280–4000 nm, and under AM1.5 spectral conditions, the weighted average absorption efficiency reaches 97.66 %, the bandwidth with an absorption efficiency greater than 90 % reaches 3750 nm. To explore the reason for achieving ultra-broadband absorption with this structure, the electromagnetic field distribution at three absorption peaks was calculated. The results revealed that the resonance between the polarization direction of the three-layer circular ring stacked structure and the plasmon resonance at the junction of Ti and SiO2 contribute to the model's capability for ultra-broadband high-efficiency absorption. At the same time, the thermal emissivity of the structure was calculated at high temperatures of 1000 K and 2000 K, both exceeding 97 %. Furthermore, due to the fully symmetrical design, the absorber is polarization-independent. It was found through calculations that whether in TM mode or TE mode, as the incident angle varies from 0° to 60°, the average absorption efficiency of the absorber changes only by 11.16 %, thereby verifying the structure's excellent insensitivity to incident light angles. In summary, all these characteristics indicate that the model has excellent application prospects in fields such as solar energy collection and photothermal conversion.

Bioremediation by Brevibacterium sediminis: a prospective pyrene degrading agent to eliminate environmental polycyclic aromatic hydrocarbons.

Environmental abuses and subsequent array of health hazards by petroleum products have emerged as a global concern that warrants proper remediation. Pyrene (PYR), a polycyclic aromatic hydrocarbon, is a xenobiotic by-product during crude petroleum processing. Biodegradation potential of two bacterial isolates (MK4 and MK9) of Brevibacterium sediminis from oil contaminated sites was explored. MK4 and MK9 could degrade PYR up to 23 and 59% (1000 mg.L- 1), respectively. A first-order formalism with the rate constant for MK4 and MK9 were found to be 0.022 ± 0.001 and 0.081 ± 0.005 day- 1, respectively with the corresponding half life period of 31.4 ± 1.4 and 8.6 ± 0.60days respectively. Both the isolates produce biosurfactants as established by drop collapse assay, oil spreading and emulsification activity studies. Decrease in pH, change in absorbance (bacterial growth), and catechol formation support adaptation capability of the isolates to degrade PYR by using it as a source of carbon. PYR ring cleavage was induced by the ring hydroxylating dioxogenase enzyme present in the strains, as identified by PCR assay. In silico analyses of the PYR degrading enzyme revealed its higher binding affinity (-7.6 kcal.mol- 1) and stability (Eigen value:1.655763 × 10- 04) to PYR, as further supported by other thoeroretical studies. MK9 strain was more efficient than the MK4 strain in PYR degradation. Studies gain its prominence as it reports for the first time on the aptitude of B. sediminis as novel PYR-degrading agent that can efficiently be used in the bioremediation of petroleum product pollution with a greener approach.

Synthesis and Binding Properties of High-Affinity Histidine-Bearing Polymers for Wood Lignin.

The pursuit of molecules capable of binding to wood lignin is pivotal for advancing lignin degradation technology, particularly when combined with lignin degradation catalysts. In this study, synthetic polymers bearing histidine moieties, demonstrating remarkable affinity for wood lignin are reported. These polymers, featuring varying degrees of histidine substitution in the form of histidine methyl esters, are synthesized through controlled radical polymerization of an activated ester-bearing monomer, employing a fluorescein-labeled chain transfer agent and subsequent postpolymerization amidation with histidine methyl ester. The binding properties of these histidine-bearing polymers with milled wood lignin under aqueous conditions are investigated. Qualitative assessment of lignin-binding capabilities involve spectroscopic analysis of changes in absorbance of visible light and fluorescence intensity. Furthermore, quantitative evaluation is conducted through surface plasmon resonance measurements to determine the binding parameters of the polymers with wood lignin. Notably, polymers with higher histidine substitution exhibit enhanced binding affinity compared to those with lower histidine substitution levels.

Exploring the potential use of Caenorhabditis elegans as an animal model for evaluating chemical-induced intestinal dysfunction

Evaluating intestinal toxicity is crucial for identifying and preventing the harmful effects of environmental chemicals. Owing to the limitations of existing models in evaluating intestinal toxicity, the development of alternative models is urgently needed. This study explored the potential use of the nematode Caenorhabditis elegans as a model animal for assessing chemical-induced intestinal dysfunction. Changes in intestinal permeability and nutrient absorption in C. elegans individuals exposed to four intestine-disrupting chemicals (sodium dodecyl sulfate (SDS), dextran sulfate sodium (DSS), lipopolysaccharide (LPS) and ethanol) were examined using dye stain assays, an enzymatic photometric assay, and fluorescent probe uptake assays. Additionally, epigallocatechin-3-gallate (EGCG), an intestine-protecting phytochemical, was chosen to prevent ethanol-induced intestinal damage. The results indicated that SDS, DSS, LPS, and ethanol compromised the intestinal barrier in C. elegans. SDS had no effect on glucose absorption, but LPS, DSS, and ethanol inhibited or tended to inhibit glucose absorption. SDS, DSS, LPS, and ethanol reduced fatty acid absorption. LPS increased peptide absorption at a low dose but decreased it at a high dose; SDS, DSS, and ethanol attenuated peptide absorption. EGCG protected against the disruption of the intestinal barrier that was induced by ethanol treatment. These results suggest that C. elegans is a suitable surrogate model animal for evaluating chemical-induced intestinal dysfunction. These findings also provide new insights into the effects of SDS, DSS, LPS, and ethanol on intestinal function and highlight the potential of EGCG as a natural dietary intervention to protect individuals who use excess alcohol from intestinal injury.

The universality of the machine: labour process theory and the absorption of the skills and knowledge of labour into capital

This article contends that deskilling is best understood not as a distinct phenomenon, but as a component of a process Marx (1993: 694) called ‘absorption’. Absorption involves not only the extraction of capacities from labour but also their implementation in machines. The article reads Braverman’s (1998) analysis of Taylorism as a demonstration of how absorption entails a specific labour process of its own, which I call the absorption process. The nature of the absorption process is contingent on many social factors. This article focuses on a technical factor: the particular machines used to implement captured skills and knowledge, called here the infrastructure of absorption. Since technological capacities are ever-evolving under capital due to the continual revolutionizing of the means of production, infrastructures of absorption change over time and this necessitates new absorption processes. Braverman (1998: 132) pointed to a qualitative change in absorption with the digital computer, which he described in terms of a new ‘universality of the machine’. While Braverman rightly pointed out the computer as a novel infrastructure, he did not discern qualitative changes to the absorption process, seeing instead the extension of Taylorist processes of capture of knowledge and skill. I contend that a qualitative shift has become apparent since the rise of machine learning in around 2015. Machine learning enables a different absorption process of emergence which does not require the codification of captured knowledge. Much labour process theory (LPT) (and adjacent) research presumes that deskilling and automation operate in terms of a process of capture, however, I show that emergence presents qualitatively different means for both. I suggest that the infrastructure of machine learning presents the possibility of task-agnostic automation.

Understanding and simulating mechanochromism in dye-dispersed polymer blends: from atomistic insights to macroscopic properties.

In this work, we propose a computational protocol enabling the simulation of mechanochromic responses in dye-dispersed polymer blends. The main objective is the modeling of the molecular-level structural changes responsible for the modulation of the photophysical properties that lead to the mechanochromic phenomenon. In this demonstrative study, we focus on predicting the changes in optical absorption displayed by a model system consisting of a dimer of a tetraphenylethylene derivative dispersed in a polyethylene matrix. The blend is subjected to an external stimulus that causes a modulation of the polymer matrix density that translates, in turn, into the emergence of specific mechanical constraints on the optically active dimers. The accurate description of this phenomenon requires the reliable sampling of the dimer configurations induced by the interaction with the matrix under stress. These molecular geometries are associated with modified electronic structures that confer novel absorption responses to the dispersed dyes. In the present contribution, the sampling of these structures is achieved through classical molecular dynamics (MD) simulations including a model element to apply an anisotropic mechanical force. This element allows the microscopic modeling of the chains' and dyes' structural rearrangements under stress. After the sampling, we compare the results of two approaches for the prediction of the optical response: (i) the calculation of a mean response from a statistical average over quantum chemical calculations on the sampled MD structures and (ii) a prediction via a more expensive hybrid scheme allowing the relaxation of the sampled molecular geometries in the presence of the matrix constraints.

Effect of Aggregated Lysozyme on Fluorescence Properties of Rose Bengal.

Protein aggregates cause abnormal states and trigger various diseases, including neurodegenerative disorders. This study examined whether the xanthene dye derivative Rose Bengal could track a series of conformational changes in protein aggregates. Using lysozyme as a model protein, aggregated proteins were prepared by heating under acidic conditions. The absorption spectra, steady-state fluorescence spectra, fluorescence quantum yield, fluorescence lifetime, and phosphorescence lifetime of a solution containing Rose Bengal in the presence of aggregated lysozyme were measured to identify their spectroscopic characteristics. The absorption spectrum of Rose Bengal changed significantly during the formation of agglomerates in heated lysozyme. Additionally, the fluorescence intensity decreased during the initial stages of the aggregation process with an increase in heating time, followed by an increase in intensity along with a red-shift of the peak wavelength. The decrease in quantum yield with a fixed fluorescence lifetime supported the formation of a nonfluorescent ground-state complex between Rose Bengal and the aggregated lysozyme. Based on the characteristic changes in absorption and fluorescence properties observed during the aggregation process, Rose Bengal is considered an excellent indicator for the sensitive discernment of aggregated proteins.

Proposal for Low-Cost Optical Sensor for Measuring Flow Velocities in Aquatic Environments.

The ocean, with its intricate processes, plays a pivotal role in shaping marine life, habitats, and the Earth's climate. This study addresses issues such as beach erosion, the survival of propagules from species like Posidonia oceanica, and nutrient distribution. To tackle these challenges, we propose an innovative sensor that quantifies hydrodynamic velocity by measuring the output voltage derived from detecting changes in light absorption and scattering using LEDs and LDRs. Our results not only demonstrate the effectiveness of the sensor but also the accuracy of the processing algorithm. Notably, the blue LED exhibited the lowest mean relative error of 7.59% in freshwater, while the yellow LED was most precise in chlorophyll-containing water, with a mean relative error of 6.80%. In a runoff simulation, we observed similar velocities with the blue, green, and white LEDs, 6.89 cm/s, 6.99 cm/s, and 7.05 cm/s, respectively, for nearly identical time intervals. It is important to highlight that our proposed sensor is not only effective but also highly cost-efficient, representing less than 0.43% of the cost of a Nortek Vector 6 MHz and 0.18% of the Teledyne Workhorse II 300 kHz Marine. This makes it a key tool for managing marine ecosystems sustainably.