Search Results (15,125)

In this study, we synthesized a fluorescent material by modifying the C-2 amino group of carboxymethyl chitosan with a rhodamine B derivative, which was proposed and demonstrated using ¹H NMR and FT-IR measurements. A series of experiments including selectivity, sensitivity, reversibility, pH, and water content were conducted to investigate the fluorometric and colorimetric properties of the grafted polymer. Utilizing a Fe³⁺-induced ring-opening mechanism of the rhodamine B spirolactam, we found that the grafted polymer exhibited a highly selective fluorescence response to Fe³⁺, with enhanced fluorescence at 583 nm compared to other tested metal ions and anions, accompanied by the characteristic absorption peak of rhodamine B that appeared at 561 nm with a noticeable color change from colorless to pink, facilitating visual observation. Additionally, the modified probe, composed of carboxymethyl chitosan, was easily regenerated through treatment with EDTA. Full article

This paper studies the computational complexity of subclasses of semiperfect rings from the perspective of computability theory. A ring is semiperfect if the identity can be expressed as a sum of mutually orthogonal local idempotents. Semisimple rings and local rings are typical subclasses of semiperfect rings that play important roles in noncommutative algebra. First, we define a ring to be semisimple if the left regular module can be decomposed as a finite direct sum of simple submodules and prove that the index set of computable semisimple rings is Σ20-hard within the index set of computable rings. Second, we define local rings by using equivalent properties of non-left invertible elements of rings and show that the index set of computable local rings is Π20-hard within the index set of computable rings. Finally, based on the Π20 definition of local rings, computable semiperfect rings can be described by Σ30 formulas. As a corollary, we find that the index set of computable semiperfect rings can be both Σ20-hard and Π20-hard within the index set of computable rings. Full article

Background: Men’s Olympic boxing follows a regulatory temporal structure, but previous studies have shown that this structure varies during competitions. However, these investigations have not thoroughly analyzed the differences in bout development according to weight category. Additionally, most studies have focused on a limited number of categories, leaving gaps in the temporal analysis of various categories. Aim: To determine the temporal structure in the featherweight, lightweight, welterweight, light heavyweight, and heavyweight categories of men’s Olympic boxing, in order to establish models that can help adjust training to meet competitive demands. Methods: An observational approach was used, analyzing 73 bouts involving 80 boxers who competed in the 2020 Tokyo Olympic Games. Results: Most bouts ended after the completion of the full regulation time across all categories. The most common actions were short punching sequences (two to five punches), occurring mainly in the center of the ring. Differences between weight categories were minimal, with the welterweight category showing the most variability. Conclusion: This study presents temporal models that will help coaches and boxers adjust their training with greater precision, improving the efficiency of training sessions according to competitive objectives. Full article

The present study investigated the changes in the organoleptic characteristics, nutraceuticals, and antioxidant activity of tomato fruits subjected to different thermal processes: tomato sauce (80 °C for 30 min), blanching treatment (100 °C for 10 s), and the superheated steam method (SHS; 100 °C for 7 min) compared with fresh tomato fruit. Even though SHS negatively modified the color of the product (L* −7% than fresh tomatoes), it was the only technology able to increase the antioxidant activity compared with fresh tomatoes (e.g., +40.3% in ABTS assay), whilst lycopene and ascorbic acid contents reported similar values to fresh tomatoes. Regarding lycopene, only 5Z-lycopene (with a higher bioavailability than (all-E)-isomers) was found in all samples, and SHS maintained the same level observed in fresh tomato fruit. Furthermore, SHS technology preserved the antioxidant effects of fresh tomato extract even in human endothelial cells. This result confirmed those obtained in previous “cell-free” assays and demonstrated that SHS treatment significantly maintains the biological properties of tomato fruit in preventing oxidative stress. However, heat-treated tomato extracts did not show the same effects as fresh tomato extract against noradrenaline-induced vasoconstriction in isolated rat aortic rings. This study demonstrates that the use of SHS technology can be considered an innovative and sustainable thermal process (in terms of maintaining the nutraceutical quality) for tomato fruits, thus paving the way for future investigations on the effects of fresh and heat-treated tomatoes after intestinal absorption in vitro and in vivo. Full article

The genus Ephedra Tourn. ex L. (Ephedraceae) is an important source with pharmacological and environmental potential. Conversely, Ephedra spp. still exhibit taxonomic complexity, especially for the specimens lacking reproductive cones. This complexity is attributed to its xeromorphic features, notably the reduced leaves and analogous assimilating branches, which make the species identification a real challenge. The current study provides a pioneering approach to distinguish fragments of Ephedra species at the gender level. This study was based on the stem anatomy and stem epidermal features using a light microscope for five species (E. alata Decne., E. aphylla Forssk., E. ciliata Fisch. & C.A.Mey., E. foeminea Forssk. and E. Ephedra pachyclada Boiss.) represented by ten genders collected from S. Sinai, Egypt. Anomocytic and brachyparacytic stomata, tanniniferous idioblasts, annual rings, a terete and furrowed outline, the number and width of tracheids, patches of cortical fibers, unicellular trichomes, druses, solitary crystals, and the activity of interfascicular cambium were among the distinguishing features that were found. Different statistical analyses were applied to explore the diversity at interspecific and intra-generic levels. This study revealed that the stem anatomy was not only an efficient tool for identifying the investigated five Ephedra species at the species level but also presented a differential key to distinguish between genders and species. In addition, our results indicated that the epidermal features played a critical role in differentiating the studied Ephedra species at the gender level. This study confirms the efficacy of stem anatomy as an identification approach for the Ephedra species at the gender level and recommends this approach to identify the fragmented Ephedra for taxonomical, pharmaceutical, and medical applications. Full article

Scorpion stings are a significant public health concern globally, particularly in tropical and subtropical regions. Scorpion venoms contain a diverse array of bioactive peptides, and different scorpion species around the world typically exhibit varying venom profiles, resulting in a wide range of envenomation symptoms. Despite their harmful effects, scorpion venom peptides hold immense potential for drug development due to their unique characteristics. Therefore, the establishment of a comprehensive database that catalogs scorpions along with their known venom peptides and proteins is imperative in furthering research efforts in this research area. We hereby present ScorpDb, a novel database that offers convenient access to data related to different scorpion species, the peptides and proteins found in their venoms, and the symptoms they can cause. To this end, the ScorpDb database has been primarily advanced to accommodate data on the Iranian scorpion fauna. From there, we propose future community efforts to include a larger diversity of scorpions and scorpion venom components. ScorpDb holds the promise to become a valuable resource for different professionals from a variety of research fields, like toxinologists, arachnologists, and pharmacologists. The database is available at https://www.scorpdb.com/. Full article

The selection of the optimal 35 kV network structure is crucial for modern distribution networks. To address the problem of balancing investment costs and reliability benefits, as well as to establish the target network structure, firstly, the investment cost of the distribution network is calculated based on the determined number of network structure units. Secondly, reliability benefits are measured by combining the comprehensive function of user outage losses with the System Average Interruption Duration Index (SAIDI). Then, a multi-objective planning model of the network structure is established, and the weighted coefficient transformation method is used to convert reliability benefits and investment costs into the total cost of power supply per unit load. Finally, by using the influencing factors of the network structure as the initial population and setting the minimum total cost of the unit load as the fitness function, the DE algorithm is employed to obtain the optimal grid structure under continuous load density intervals. Case studies demonstrate that different load densities correspond to different optimal network structures. For load densities ranging from 0 to 30, the selected optimal network structures from low to high are as follows: overhead single radial, overhead three-section with two ties, cable single ring network, and cable dual ring network. Full article

High-capacity communication networks are built to provide high throughput and low latency to accommodate the growing demand for bandwidth. However, the provision of these features is subject to a robust underlying network, which can provide high capacity with maximum reliability in terms of the system’s connection availability. This work optimizes an existing 2D spectral–spatial optical code division multiple access (OCDMA) passive optical network (PON) to maximize connection availability while maintaining desirable communication capacity and capital expenditure. Optimization is performed by employing ring topology at the feeder level, which is used to provide a redundant path in case of connection failures. Furthermore, high transmission capacity is ensured by utilizing a pseudo-3D double-weight zero cross-correlation (DW-ZCC) code. The analysis is performed with Optisystem simulations to observe the performance of the system in terms of bit error rate (BER), received power, and eye openings. It is observed that the introduction of ring topology at the feeder level of the PON does not impact the overall transmission capacity of the system. The system can still support maximum transmission capacity at receiver sensitivities of up to −19 dB. Reliability analysis also shows that the optimized ring-based architecture can provide desirable connection availability compared to the existing system. Full article

Forest fires are a major global environmental problem, especially for forest ecosystems and specifically in Mediterranean climate zones. These fires can seriously impact hydrologic processes and soil erosion, which can cause water pollution and flooding. The aim of this work is to assess the effect of forest fire on the hydrologic processes in the soil, depending on soil properties. For this purpose, the infiltration rate has been measured by ring infiltration tester, and the hydrophobicity has been quantified by the “water drop penetration time” method in several soils of burnt and unburnt forest areas in the Mediterranean mountains. The infiltration rates obtained are higher in burnt than in unburnt soils (1130 and 891 mm·h⁻¹, respectively), which contradicts most of the research in Mediterranean climates in southeast Spain with calcareous soils. Burnt soils show no hydrophobicity on the surface, but it is there when the soil is excavated by 1 cm. Additionally, burnt soils reveal a low frequency of hydrophobicity (in less than 30% of the samples) but more severe hydrophobicity (above 300 s); whereas, in unburnt soils, the frequency is higher (50%) but the values of hydrophobicity are lower. The results obtained clearly show the infiltration processes modified by fire, and these results may be useful for land managers, hydrologists, and those responsible for decision-making regarding the forest restoration of burnt land. Full article

The disorder and heterogeneity of low-molecular-weight amyloid-beta oligomers (AβOs) underlie their participation in multiple modes of cellular dysfunction associated with the etiology of Alzheimer’s disease (AD). The lack of specified conformational states in these species complicates efforts to select or design small molecules to targeting discrete pathogenic states. Furthermore, targeting AβOs alone may be therapeutically insufficient, as AD progresses as a multifactorial, self-amplifying cascade. To address these challenges, we have screened the activity of seven new candidates that serve as Paramagnetic Amyloid Ligand (PAL) candidates. PALs are bifunctional small molecules that both remodel the AβO structure and localize a potent antioxidant that mimics the activity of SOD within live cells. The candidates are built from either a stilbene or curcumin scaffold with nitroxyl moiety to serve as catalytic antioxidants. Measurements of PAL AβO binding and remolding along with assessments of bioactivity allow for the extraction of useful SAR information from screening data. One candidate (HO-4450; PMT-307), with a six-membered nitroxyl ring attached to a stilbene ring, displays the highest potency in protecting against cell-derived Aβ. A preliminary low-dose evaluation in AD model mice provides evidence of modest treatment effects by HO-4450. The results for the curcumin PALs demonstrate that the retention of the native curcumin phenolic groups is advantageous to the design of the hybrid PAL candidates. Finally, the PAL remodeling of AβO secondary structures shows a reasonable correlation between a candidate’s bioactivity and its ability to reduce the fraction of antiparallel β-strand. Full article

2,6-Dipicolinoylbis(N,N-dialkylthioureas) and H₂L^R2 react with uranyl salts and a supporting base (e.g., NEt₃) under formation of monomeric or oligomeric complexes of the compositions [UO₂(L^R2)(solv)] (solv = donor solvents) or [{UO₂(L^R2)(µ₂-OMe)}₂]^2–. In such complexes, the uranyl ions are commonly coordinated by the “hard” O,N,O or N,N,N donor atom sets of the central ligand unit and the lateral sulfur donor atoms remain uncoordinated. Their individual structures, however, depend on the reaction conditions, particularly on the equivalents of NEt₃ used. An unprecedented, selective hydrolysis of the uranium-coordinating bis(thioureato) ligands results in an S/O donor atom exchange at exclusively one thiourea side-arm, when an excess of NEt₃ is used. The resulting trimeric uranyl complexes are isolated in fair yields and have a composition of [(UO₂)₃(L^2Et2)₂(µ₂–OR)(µ₃-O)]^–. H₂L^2Et2 represents the newly formed 2,6-dipicolinoyl(N,N-diethylthiourea)(N,N-diethylurea) and R = H, Me, or Et. {L^2Et2}^2– binds to the uranyl units via the pyridine ring, the dialkylurea arm, and the central carbonyl groups, while the thiourea unit remains uncoordinated. The central cores of the products consist of oxido-centered triangular {(UO₂)₃O}⁴⁺ units. The observed reactivity is metal-driven and corresponds mechanistically most probably to a classical metal-catalyzed hydrodesulfurization. The hydrolytic thiourea/urea conversion is only observed in the presence of uranyl ions. The products were isolated in crystalline form and studied spectroscopically and by X-ray diffraction. The experimental findings are accompanied by DFT calculations, which help to understand the energetic implications in such systems. Full article

Background/Objectives: Tinnitus is a debilitating auditory disorder commonly described as a ringing in the ears in the absence of an external sound source. Sound trauma is considered a primary cause. Neuronal hyperactivity is one potential mechanism for the genesis of tinnitus and has been identified in the cochlear nucleus (CN) and the auditory cortex (AC), where there may be an imbalance of excitatory and inhibitory neurotransmissions. However, no study has directly correlated tinnitus with the extracellular levels of amino acids in the CN and the AC using microdialysis, which reflects the functions of these neurochemicals. In the present study, rats were exposed to acoustic trauma and then subjected to behavioural confirmation of tinnitus after one month, followed by microdialysis. Methods: Rats were divided into sham (aged, n = 6; young, n = 6); tinnitus-positive (aged, n = 7; young, n = 7); and tinnitus-negative (aged, n = 3; young, n = 3) groups. In vivo microdialysis was utilized to collect samples from the CN and the AC, simultaneously, in the same rat. Extracellular levels of amino acids were quantified using high-performance liquid chromatography (HPLC) coupled with an electrochemical detector (ECD). The effects of sound stimulation and age on neurochemical changes associated with tinnitus were also examined. Results: There were no significant differences in either the basal levels or the sound stimulation-evoked changes of any of the amino acids examined in the CN and the AC between the sham and tinnitus animals. However, the basal levels of serine and threonine exhibited age-related alterations in the AC, and significant differences in threonine and glycine levels were observed in the responses to 4 kHz and 16 kHz stimuli in the CN. Conclusions: These results demonstrate the lack of a direct link between extracellular levels of amino acids in the CN and the AC and tinnitus perception in a rat model of tinnitus. Full article

The treatment of cancer represents one of the most significant challenges currently facing modern medicine. The search for new drugs that are effective in the treatment of patients is an ongoing endeavor. It is frequently the case that the molecular target of anticancer drugs is a DNA molecule. The therapeutic effect of a drug is achieved by influencing the structure of a macromolecule or by inhibiting its function. Among the synthetic substances with potential anticancer effects, particular attention should be paid to phthalic acid imide derivatives. Three phthalimide derivatives are employed in the treatment of multiple myeloma: thalidomide, pomalidomide, and lenalidomide. Nevertheless, the search for new derivatives with a diverse range of biological activities is ongoing. In light of the above, the subject of our investigation is four non-toxic phthalic acid imide derivatives. The objective was to analyze the interaction of these compounds with DNA. The use of spectroscopic and in silico methods has enabled us to demonstrate that all of the tested analogs can act as ligands for deoxyribonucleic acid, forming non-covalent bonds with it. All four compounds tested interact with the ctDNA molecule, binding in its minor groove. The most stable complex is formed here between deoxyribonucleic acid and the C derivative, in which the -CF₃ group is attached to the benzene ring. What is interesting and important, the described mechanism of action is analogous to that observed between ctDNA and thalidomide, pomalidomide, and lenalidomide. Full article

In this paper, an inductively coupled capacitively loaded ring resonator (IC-CLRR)-based microwave resonant sensor has been proposed for the accurate identification of any unknown liquid sample and its permittivity estimation. The key element of this work is the sensor’s wide range capability towards the non-invasive testing of liquids covering a wide dielectric range of liquid samples, i.e., ε_r = 2 to 80. The proposed microwave sensor is etched over the FR-4 substrate and is excited by the microstrip line through inductive coupling. The placement of an unknown liquid sample in close proximity to the sensor alters its natural resonant frequency due to a change in effective inductance and capacitance as per the dielectric property of the liquid sample. Further, a mathematical formulation using curve fitting has also been derived. The measurement results show a good accuracy in estimating the permittivity and, thus, the unknown liquid identification capability of the designed sensor with a very low error (nearly 5%). This sensor design is simple to fabricate, cost-friendly, and small in size. Full article

In modern infrastructure construction, the socket joint of concrete pipelines is a critical component in ensuring the overall stability and safety of the pipeline system. This study conducted monotonic and cyclic bending loading tests on DN300 concrete pipeline socket joints to thoroughly analyse their bending mechanical properties. The experimental results indicated that during monotonic loading, the relationship between the joint angle and bending moment exhibited nonlinear growth, with the stress state of the socket joint transitioning from the initial contact between the rubber ring and the socket to the eventual contact between the spigot and socket concrete. During the cyclic loading phase, the accumulated joint angle, secant stiffness, and bending stiffness of the pipeline interface significantly increased within the first 1 to 7 cycles and stabilised between the 8th and 40th cycles. After 40 cycles of loading, the bending stiffness of the joint reached 1.5 kN·m², while the stiffness of the pipeline was approximately 8500 times that of the joint. Additionally, a finite element model for the monotonic loading of the concrete pipeline socket joint was established, and the simulation results showed good agreement with the experimental data, providing a reliable basis for further simulation and analysis of the joint’s mechanical performance under higher loads. This study fills the gap in research on the mechanical properties of concrete pipeline socket joints, particularly under bending loads, and offers valuable references for related engineering applications. Full article