Search Results (16)

Cryptic sites, which are transient binding sites that emerge through protein conformational changes upon ligand binding, are valuable targets for drug discovery, particularly for allosteric modulators. However, identifying these sites remains challenging because they are often discovered serendipitously when both ligand-binding (holo) and ligand-free (apo) states are experimentally determined. Here, we introduce CrypTothML, a novel framework that integrates mixed-solvent molecular dynamics (MSMD) simulations and machine learning to predict cryptic sites accurately. CrypTothML first identifies hotspots through MSMD simulations using six chemically diverse probes (benzene, dimethyl-ether, phenol, methyl-imidazole, acetonitrile, and ethylene glycol). A machine learning model then ranks these hotspots based on their likelihood of being cryptic sites, incorporating both hotspot-derived and protein-specific features. Evaluation on a curated dataset demonstrated that CrypTothML outperforms recent machine learning-based methods, achieving an AUC-ROC of 0.88 and successfully identifying cryptic sites missed by other methods. Additionally, CrypTothML ranked cryptic sites as the top prediction more frequently than existing methods. This approach provides a powerful strategy for accelerating drug discovery and designing allosteric drugs. Full article

New quaternary ammonium derivatives (quats) based on apple pectin (PA) were synthesized by the chemical modification of native polysaccharides with various quaternization mixtures containing epichlorohydrin (ECH) and a tertiary amine. Pectin derivatives (QPAs) were studied by elemental analysis, conductometric titration, Fourier-transform infrared spectroscopy (FTIR), and ¹³C nuclear magnetic resonance (¹³C NMR). Viscosity measurements enabled the evaluation of the viscosity average molar mass (M_v) for the unmodified polysaccharide, as well as its intrinsic viscosity ([η]) value. Dynamic light scattering (DLS) analysis revealed that the PA and its quats formed aggregates in an aqueous solution with either a unimodal (PA) or bimodal (QPAs) distribution. Scanning transmission electron microscopy analysis (STEM) of the PA and its derivatives demonstrated the presence of individual polymeric chains and aggregates in aqueous solution, with the smallest sizes being specific to amphiphilic polymers. Thermal stability, as well as wide-angle X-ray diffraction (WAXD) studies, generally indicated a lower thermal stability and crystallinity of the QPAs compared with those of the PA. Antipathogenic activity demonstrated that the PA and its derivatives exhibited effectiveness against S. aureus ATCC 25923 bacterium and C. albicans ATCC 10231 pathogenic yeast. Full article

This scoping review addresses bacterial contamination of antiseptics, low-level disinfectants, and hand hygiene products in healthcare settings in high-income countries. Over 70 years, 114 articles were found: 68 outbreaks, 13 pseudo-outbreaks and 33 cross-sectional surveys. Outbreaks affected median 29 (1–151) patients, extended for 26 (1–156) weeks and had a case fatality of 0.0% (0.0–60.0%). Most (72.8%) (pseudo-)outbreaks were caused by water-based chlorhexidine (CHG), quaternary ammonium compounds (QUAT) and the combination CHG–QUAT. Contaminating bacteria were nonfermentative Gram-negative rods (87.6% (pseudo-)outbreaks), mainly Burkholderia cepacia, Pseudomonas aeruginosa and Achromobacter spp.) and Enterobacterales (29.6%, 24/81), mostly Serratia spp.). Risk factors were at the level of the bacteria (natural resistance to CHG and QUAT), containers (design and functioning, presence of cork and cotton, biofilm formation), preparation (nonsterile water, overdilution) and practices (too long expiry dates, inappropriate container reprocessing, topping up of containers and deviation from procedures). Transmission occurred through direct contact (antiseptics), contact with semicritical items (disinfectants) and were handborne (soaps). During recent decades, reports of soap contaminated with Enterobacterales emerged and nationwide outbreaks of intrinsically contaminated CHG occurred. Outstanding issues comprise intrinsic contamination, implementation of antiseptic stewardship, the role of unit doses and sterile products, transmission studies, biofilm control and understanding healthcare providers’ perceptions. Full article

Knowledge Graph Embedding (KGE) is a powerful way to express Knowledge Graphs (KGs), which can help machines learn patterns hidden in the KGs. Relation patterns are useful hidden patterns, and they usually assist machines to predict unseen facts. Many existing KGE approaches can model some common relation patterns like symmetry/antisymmetry, inversion, and commutative composition patterns. However, most of them are weak in modeling noncommutative composition patterns. It means these approaches can not distinguish a lot of composite relations like “father’s mother” and “mother’s father”. In this work, we propose a new KGE method called QuatRotatScalE (QRSE) to overcome this weakness, since it utilizes rotation and scaling transformations of quaternions to design the relation embedding. Specifically, we embed the relations and entities into a quaternion vector space under the difference norm KGE framework. Since the multiplication of quaternions does not satisfy the commutative law, QRSE can model noncommutative composition patterns naturally. The experimental results on the synthetic dataset also support that QRSE has this ability. In addition, the experimental results on real-world datasets show that QRSE reaches state-of-the-art in link prediction problem. Full article

Biodegradation is among the most common issues affecting Cultural Heritage stone materials in outdoor environments. In recent years, the application of chemical agents with biocidal activity has been the most usual practice when dealing with biofilm removal. In outdoor environments, the use of these biocides is not effective enough, since the materials are constantly exposed to environmental agents and atmospheric pollutants. Thus, it becomes necessary to protect the surface of Cultural Heritage works with antimicrobial coatings to either prevent or at least limit future colonization. In this study, innovative biocides—both natural and synthetic—were applied on a Roman mosaic located in the Archaeological Park of Ostia Antica to compare their effectiveness in removing the biological degradation affecting it. In addition, an antimicrobial coating called “SI-QUAT” was applied and analyzed in situ. SI-QUAT has recently entered the market for its prevention activity against biocolonization. The biocidal activity of these products was tested and monitored using different analytical portable instruments, such as the multispectral system, the spectrocolorimeter, and the bioluminometer. The analyses showed that promising results can be obtained using the combination of the biocide and the protective effect of Preventol^® RI50 and SI-QUAT. Full article

Robust quantization watermarking with perceptual JND model has made a great success for image copyright protection. Generally, either restores each color channel separately or processes the vector representation from three color channels with the traditional monochromatic model. And it cannot make full use of the high correlation among RGB channels. In this paper, we proposed a robust quaternion JND Model for color image watermarking (QuatJND). In contrast to the existing perceptual JND models, the advantage of QuatJND is that it can integrate quaternion representation domain and colorfulness simultaneously, and QuatJND incorporates the pattern guided contrast masking effect in quaternion domain. On the other hand, in order to efficiently utilize the color information, we further develop a robust quantization watermarking framework using the color properties of the quaternion DCT coefficients in QuatJND. And the quantization steps of each quaternion DCT block in the scheme are optimal. Experimental results show that our method has a good performance in term of robustness with better visual quality. Full article

Medical textiles are one of the most rapidly growing parts of the technical textiles sector in the textile industry. This work aims to investigate the medical applications of a curcumin/TiO₂ nanocomposite fabricated on the surface of cotton fabric. The cotton fabric was pretreated with three crosslinking agents, namely citric acid, 3-Chloro-2-hydroxypropyl trimethyl ammonium chloride (Quat 188) and 3-glycidyloxypropyltrimethoxysilane (GPTMS), by applying the nanocomposite to the modified cotton fabric using the pad-dry-cure method. The chemistry and morphology of the modified fabrics were examined by Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. In addition, the chemical mechanism for the nanocomposite-modified fabric was reported. UV protection (UPF) and antibacterial properties against Gram-positive S. aureus and Gram-negative E. coli bacterial strains were investigated. The durability of the fabrics to 20 washing cycles was also examined. Results demonstrated that the nanocomposite-modified cotton fabric exhibited superior antibacterial activity against Gram-negative bacteria than Gram-positive bacteria and excellent UV protection properties. Moreover, a good durability was obtained, which was possibly due to the effect of the crosslinker used. Among the three pre-modifications of the cotton fabric, Quat 188 modified fabric revealed the highest antibacterial activity compared with citric acid or GPTMS modified fabrics. This outcome suggested that the curcumin/TiO₂ nanocomposite Quat 188-modified cotton fabric could be used as a biomedical textile due to its antibacterial properties. Full article

Table eggs are an affordable yet nutritious protein source for humans. Unfortunately, eggs are a vector for bacteria that could cause foodborne illness. This study aimed to investigate the effectiveness of a quaternary ammonium compound (quat) sanitizer against aerobic mesophilic bacteria, yeast, and mold load on the eggshell surface of free-range and commercial farms and the post-treatment effect on microbial load during storage. Total aerobic mesophilic bacteria, yeast, and molds were enumerated using plate count techniques. The efficacy of the quaternary ammonium sanitizer (quat) was tested using two levels: full factorial with two replicates for corner points, factor A (maximum: 200 ppm, minimum: 100 ppm) and factor B (maximum: 15 min, minimum: 5 min). Quat sanitizer significantly (p < 0.05) reduced approximately 4 log10 CFU/cm² of the aerobic mesophilic bacteria, 1.5 to 2.5 log10 CFU/cm² of the mold population, and 1.5 to 2 log10 CFU/cm² of the yeast population. However, there was no significant (p ≥ 0.05) response observed between individual factor levels (maximum and minimum), and two-way interaction terms were also not statistically significant (p ≥ 0.05). A low (<1 log10 CFU/cm²) aerobic mesophilic bacteria trend was observed when shell eggs were stored in a cold environment up to the production expiry date. No internal microbial load was observed; thus, it was postulated that washing with quat sanitizer discreetly (without physically damaging the eggshell) does not facilitate microbial penetration during storage at either room temperature or cold storage. Current study findings demonstrated that the quat sanitizer effectively reduced the microbial population on eggshells without promoting internal microbial growth. Full article

The objective of this work was to carry out a comprehensive evaluation of the performance of a novel cationic amino lipid surfactant, Brassicyl Valinate Esylate (BVE), in contrast to conventional alkyl quaternary ammonium surfactants (quats), through a study of the effects of process mixing speed on its overall rheological, tribological and wet lubrication performance in comparison to BTAC and CTAC, two cationic surfactants widely used in cosmetics. The major cosmetic application of cationic surfactants is in the preparation of hair conditioners. Hence, this analysis was done firstly by conducting tensile combing tests to evaluate reduction in wet lubrication which translates to conditioning performance. The combing results serve as a testing metric that adequately corresponds to consumer perception of conditioned hair. To correlate this technically, yield stress measurements were conducted to establish rheologic profiles of the conditioner formulations, and in vitro tribological testing of the emulsion systems between two steel surfaces were done to technically simulate the spreading and rubbing of conditioner on the hair. The effect of processing conditions on the formulations was then evaluated. BVE was found to be an effective conditioning surfactant suitable as an eco-friendly replacement for BTAC and CTAC in hair conditioner formulations. The results showed that higher shear mixing rates during formulation lead to poorer performance effects evident through decreased yield stress values, lower percentage reduction in combing force and a higher coefficient of friction. Full article

Dermatophytosis is a fungal infection of skin, nails and hair. Treatments can be long and infections are often recurrent, and novel treatments are desirable. Here we tested the use of polymeric films that can be sprayed on the skin for the prevention and treatment of dermatophytosis. The two polymers selected were ABIL T Quat 60 and Eudragit E100, which were tested ex vivo using a porcine skin model, and in vitro using microbiological and microscopy techniques. Acceptability of the polymeric films was tested on the skin of healthy volunteers. The results showed that ABIL and Eudragit films prevented and treated fungal skin infections. Whilst polymer films may provide a physical barrier that prevents fungal colonization, it was shown that both polymers are active antifungals ex vivo and in vitro and have intrinsic antifungal activity. For ABIL, we also established that this polymer binds essential nutrients such as metal ions and sugars, thereby restricting the growth of fungi. When applied to healthy subjects’ skin, the polymeric films neither modified the skin color nor increased trans-epidermal water loss, suggesting a low potential for skin irritation, and the approach was generally found to be acceptable for use by the volunteers. In conclusion, we developed a novel strategy for the potential prevention and treatment of dermatophytosis. Full article

The applications of knowledge graph have received much attention in the field of artificial intelligence. The quality of knowledge graphs is, however, often influenced by missing facts. To predict the missing facts, various solid transformation based models have been proposed by mapping knowledge graphs into low dimensional spaces. However, most of the existing transformation based approaches ignore that there are multiple relations between two entities, which is common in the real world. In order to address this challenge, we propose a novel approach called DualQuatE that maps entities and relations into a dual quaternion space. Specifically, entities are represented by pure quaternions and relations are modeled based on the combination of rotation and translation from head to tail entities. After that we utilize interactions of different translations and rotations to distinguish various relations between head and tail entities. Experimental results exhibit that the performance of DualQuatE is competitive compared to the existing state-of-the-art models. Full article

Foodborne pathogens are known to adhere strongly to surfaces and can form biofilms in food processing facilities; therefore, their potential to contaminate manufactured foods underscores the importance of sanitation. The objectives of this study were to (1) examine the efficacy of a new-generation sanitizer (Decon7) on Staphylococcus and Pseudomonas biofilms, (2) identify biofilm bacteria from workers’ boots in relation to previous sanitizer chemistry, (3) validate the efficacy of Decon7 on biofilm from workers’ boots from an abattoir/food processing environment, and (4) compare the sensitivity of isolated boot biofilm bacteria to new- and early (Bi-Quat)-generation QAC sanitizers. Decon7 was applied at two concentrations (5%, 10%) and was shown to be effective within 1 min of exposure against enhanced biofilms of Staphylococcus spp. and Pseudomonas spp. in 96-well microplates. Decon7 was also used to treat workers’ boots that had accumulated high levels of biofilm bacteria due to ineffective sanitization. Bacteria isolated before enzyme/sanitizer treatment were identified through 16S rRNA PCR and DNA sequencing. All treatments were carried out in triplicate and analyzed by one-way RM-ANOVA or ANOVA using the Holm–Sidak test for pairwise multiple comparisons to determine significant differences (p < 0.05). The data show a significant difference between Decon7 sanitizer treatment and untreated control groups. There was a ~4–5 log reduction in Staphylococcus spp. and Pseudomonas spp. (microplate assay) within the first 1 min of treatment and also a > 3-log reduction in the bacterial population observed in the biofilms from workers’ boots. The new next-generation QAC sanitizers are more effective than prior QAC sanitizers, and enzyme pre-treatment can facilitate biofilm sanitizer penetration on food contact surfaces. The rotation of sanitizer chemistries may prevent the selective retention of chemistry-tolerant microorganisms in processing facilities. Full article

Surfaces in a hygiene critical environment can become potential reservoirs for transmission of pathogenic infections. Engineering surfaces with the tunable anti-biofouling and antibacterial properties could reduce infections particularly in hospitals and public transport hubs. In the present work, a facile two-step process has been deployed to fabricate a superhydrophobic and antibacterial aluminum surface by chemical etching, followed by passivation with low surface energy octyltriethoxysilane (OTES) molecules. The wettability and antibacterial properties of the OTES passivated aluminum was monotonically tuned by adding quaternary ammonium (QUATs) molecules. An anti-biofouling property of 99.9% against Staphylococcus aureus, 99% against Pseudomonas aeruginosa and 99% against E. coli bacteria, was achieved. Full article

Treated wood timbers employed in ground contact are often installed with a cement collar to firmly fix the structural wood post in place. Few prior studies have determined the effect of concrete on decay efficacy on treated wood, however. Treated wood nominal 4 × 4 posts were installed at four locations, with the upper ground-contact portion of each post encased in concrete, and the samples removed at various times for pH measurements. The wood alkalinity quickly increased at all four sites for the portion of the treated wood in concrete contact compared to the wood in ground contact without concrete. In laboratory decay tests employing three decay fungi, untreated wood which was first exposed or unexposed to concrete had no consistent difference in decay susceptibility. For wood treated with three different commercial copper/organic systems, cement exposure had no effect on wood treated with an amine copper azole system, while treatment with amine copper quat showed a statistically significant fungal efficacy enhancement for cement-exposed samples with both copper-tolerant fungi. Conversely, with a micronized copper azole preservative, cement exposure resulted in reduced fungal efficacy compared to treated samples which were not cement-exposed for all three decay fungi. Full article

In this study, we used anion supramolecular solvent (SUPRAS) prepared from a mixture of an anionic surfactant, sodium dodecyl sulfate (SDS), and a cationic surfactant, tetrabutylammonium bromide (TBABr), as the extraction solvent in liquid phase microextraction (LPME) of paraquat (PQ) and diquat (DQ). The enriched PQ and DQ in the SUPRAS phase were simultaneously analyzed by ion-pairing reversed-phase high performance liquid chromatography. PQ and DQ were successfully extracted by LPME via electrostatic interaction between the positive charge of the quats and the negative charge of SUPRAS. PQ, DQ, and ethyl viologen (the internal standard) were separated within 15 min on a C18 column, with the mobile phase containing 1-dodecanesulfonic acid and triethylamine, via UV detection. The optimized conditions for the extraction of 10 mL aqueous solution are 50 μL of SUPRAS prepared from a mixture of SDS and TBABr at a mole ratio of 1:0.5, vortexed for 10 s at 1800 rpm, and centrifugation for 1 min at 3500 rpm. The obtained enrichment factors were 22 and 26 with limits of detection of 1.5 and 2.8 µg L⁻¹ for DQ and PQ, respectively. The precision was good with relative standard deviations less than 3.86%. The proposed method was successfully applied for the determination of PQ and DQ in vegetable samples and recoveries were found in the range of 75.0% to 106.7%. Full article