Initial Activity Research Articles

Customized self-assembled bimetallic hybrid nanoflowers promoting the robustness of D-allulose 3-epimerase

Enzyme-based hybrid nanoflowers, a green biocatalyst technology employing metal ions as the main driving force of enzyme immobilization without participating in the catalytic reaction, have been extensively explored to increase enzyme robustness. Here, a customized self-assembled protein-bimetallic hybrid nanoflower system (HNF) was designed to immobilize D-allulose 3-epimerase (DAEase) with a hierarchical flower-like architecture. The tailored DAEase-HNFs were extremely stable in acidic conditions, retaining more than 70 % of their initial activity after incubation in aqueous solution at pH 3.0–6.0 for 4 h. They were also durable, retaining 92.4 % relative activity after 8 consecutive cycles, and maintaining 82.3 % relative activity after storage for 30 days at 4 °C. Molecular dynamics (MD) simulations were performed to probe the self-assembly processes related to the increased robustness of the encapsulated DAEase by investigating the conformational changes in the gating switch helix of the substrate entrance, hydrogen bond networks, and the catalytic cavity. Our data indicate that HNFs are a promising immobilization strategy to improve the robustness and durability of DAEase.

Cellulose-based magnetic nanomaterials immobilized esterases as a reusable and effective detoxification agent for patulin in apple juice

Patulin, an important contaminant in apple juice processing, exhibits various toxicities to humans. In existing patulin detoxification methods, enzymes are desirable biological detoxification agents. Here, magnetic nanocrystalline cellulose (MNCC) was prepared and employed as support for the immobilization of porcine liver esterase (PLE) to synthesize a novel cellulose-based magnetic patulin detoxification agent (PLE@MNCC). The detoxification rate of patulin by PLE@MNCC exceeded 80%. PLE@MNCC also enabled rapid separation and recovery after application while exhibiting superior storage stability, reusability and biocompatibility. After 8 repetitive cycles of usage, PLE@MNCC retained approximately 50% of its initial activity. Moreover, the cytotoxicity evaluation demonstrated a significant decrease in patulin toxicity after the detoxification. Crucially, there were no significant adverse changes in the quality of apple juice after detoxification. PLE@MNCC as an effective, reusable, environmentally friendly and safe enzyme agent provided an efficient strategy for the detoxification of patulin in fruit juices.

Enhanced High-Fructose Corn Syrup Production: Immobilizing Serratia marcescens Glucose Isomerase on MOF (Co)-525 Reduces Co2+ Dependency in Glucose Isomerization to Fructose.

The escalating demand for processed foods has led to the widespread industrial use of glucose isomerase (GI) for high-fructose corn syrup (HFCS) production. This reliance on GIs necessitates continual Co2+ supplementation to sustain high catalytic activity across multiple reaction cycles. In this study, Serratia marcescens GI (SmGI) was immobilized onto surfaces of the metal-organic framework (MOF) material MOF (Co)-525 to generate MOF (Co)-525-GI for use in catalyzing glucose isomerization to generate fructose. Examination of MOF (Co)-525-GI structural features using scanning electron microscopy-energy dispersive spectroscopy, Fourier-transform infrared spectroscopy, and ultraviolet spectroscopy revealed no structural changes after SmGI immobilization and the addition of Co2+. Notably, MOF (Co)-525-GI exhibited optimal catalytic activity at pH 7.5 and 70 °C, with a maximum reaction rate (Vmax) of 37.24 ± 1.91 μM/min and Km value of 46.25 ± 3.03 mM observed. Remarkably, immobilized SmGI exhibited sustained high catalytic activity over multiple cycles without continuous Co2+ infusion, retaining its molecular structure and 96.38% of its initial activity after six reaction cycles. These results underscore the potential of MOF (Co)-525-GI to serve as a safer and more efficient immobilized enzyme technology compared to traditional GI-based food-processing technologies.

New-onset autoimmune disease after COVID-19.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) may trigger autoimmune disease (AD) through initial innate immune activation with subsequent aberrations in adaptive immune cells leading to AD. While there are multiple reports of incident AD diagnosed after COVID-19, the risk in the context of key circulating strains is unknown. TriNetX, a global, federated, health research network providing access to electronic medical records across 74 healthcare organizations, was utilized to define an adult cohort between January 1, 2020, and March 3, 2023. Exposure was defined as COVID-19 diagnosis (ICD-10 code or positive laboratory test). Age- and sex-propensity score-matched controls never had COVID-19 diagnosed. Outcomes were assessed 1 month to 1 year after the index date. Patients with AD prior to or within 1 month after the index date were excluded from the primary analysis. Incidence and risk ratios of each AD were assessed. A total of 3,908,592 patients were included. Of 24 AD patients assessed, adjusted risk ratios for eight AD patients who had COVID-19 were higher compared to those who had no COVID-19. Cutaneous vasculitis (adjusted hazard ratio (aHR): 1.82; 95% CI 1.55-2.13), polyarteritis nodosa (aHR: 1.76; 95% CI 1.15-2.70), and hypersensitivity angiitis (aHR: 1.64; 95% CI 1.12-2.38) had the highest risk ratios. Overall, psoriasis (0.15%), rheumatoid arthritis (0.14%), and type 1 diabetes (0.13%) had the highest incidence during the study period, and of these, psoriasis and diabetes were more likely after COVID-19. The risk of any AD was lower if COVID-19 was diagnosed when Omicron variants were the predominant circulating strains. A positive antinuclear antibody was more likely and predictive of AD after COVID-19. SARS-CoV-2 may be a potential trigger for some AD, but the risk for AD may decrease with time given the apparent lower risk after infection with Omicron variants.

Sex related differences in neuromuscular fatiguability between prepubertal children and young adults

Introduction
 Prepubertal children compared to adults manifest neuromuscular differences in a lower voluntary activation and fatigability, as well as a potentially lesser use of larger motor units innervating fast-twitch-fibers (Dotan et al., 2012). While children tend to fatigue more on a central than peripheral level, these trends vary based on exercise modality and muscle group (Ratel et al., 2015; Souron et al., 2022). Furthermore, females incline to fatigue less than males, but research on sex differences in children remains limited (Hunter, 2014). Therefore, the aim of this study was to investigate neuromuscular age and sex differences in a sustained isometric contraction until failure.
 Methods
 16 prepubertal children (9.2 ± 0.9y) and 16 adults (23.4 ± 2.4y; m = f) performed a maximal voluntary isometric contraction (MVCpre), a failure-task at 60%MVCpre, followed by another MVCpost of knee extensors. Surface electromyography for rectus femoris (RF), vastus medialis (VM), and vastus lateralis muscles (VL) was analysed at 0, 25, 50, 75, and 100% of the individual time to failure (TTF). Linear models and Cohen’s d effect sizes were used to quantify age and sex differences of TTF, MVCpre-post, as well as root mean square (RMS) and median frequency (MDF) of each muscle throughout the fatiguing trial.
 Results
 Trivial differences were observed in TTF across age, sex, and age*sex-interaction (d ≤ 0.78). Children displayed a larger decline in MVCpre-post (d = 1.24), whereas sex and age*sex interactions were minimal (d ≤ 0.63).
 Initially (0% TTF), children had a lower activation in RF, VL and VL (d > 1.32), whereas age-differences across the failure-task were found for RMS VL, MDF RF, VL and VM (d ≥ 0.15), with no prominent sex-differences (d ≤ 0.14). Sex*age-interaction yielded detectable results only in RMS VM (d = -0.36).
 Conclusion
 The lower ability to generate an MVCpost combined with a smaller change in EMG parameters in children could be due to more central rather than peripheral fatigue. This is also supported by the lower initial activation in adults, suggesting that larger, more fatigable motor units are initially preserved, which may not be available in children.
 The small to large effects in neuromuscular fatigability between age and sex groups indicate the need for more in-depth research (tracking of motor units, change of voluntary activation and twitch properties) particularly with regard to sex-related disparities.
 References
 Dotan, R., Mitchell, C., Cohen, R., Klentrou, P., Gabriel, D., & Falk, B. (2012). Child-adult differences in muscle activation—A review. Pediatric Exercise Science, 24(1), 2–21. https://doi.org/10.1123/pes.24.1.2
 Hunter, S. K. (2014). Sex differences in human fatigability: Mechanisms and insight to physiological responses. Acta Physiologica, 210(4), 768–789. https://doi.org/10.1111/apha.12234
 Ratel, S., Kluka, V., Vicencio, S. G., Jegu, A.-G., Cardenoux, C., Morio, C., Coudeyre, E., & Martin, V. (2015). Insights into the mechanisms of neuromuscular fatigue in boys and men. Medicine & Science in Sports & Exercise, 47(11), 2319–2328. https://doi.org/10.1249/MSS.0000000000000697
 Souron, R., Carayol, M., Martin, V., Enzo, P., Duché, P., & Gruet, M. (2022). Differences in time to task failure and fatigability between children and young adults: A systematic review and meta-analysis. Frontiers in Physiology, 13, Article 1026012. https://doi.org/10.3389/fphys.2022.1026012

An analytical model to estimate the time delay to reach spontaneous ignition considering heat loss in oil reservoirs

During air injection into an oil reservoir, an oxidation reaction generates some heat to raise the reservoir temperature. When the reservoir temperature reaches an ignition temperature, spontaneous ignition occurs. There is a time delay from the injection to ignition. There are mixed results regarding the feasibility of spontaneous ignition in real-field projects and in laboratory experiments. No analytical model is available in the literature to estimate the oxidation time required to reach spontaneous ignition with heat loss.This paper discusses the feasibility of spontaneous ignition from theoretical points and experimental and field project observations. An analytical model considering heat loss is proposed. Analytical models with and without heat loss investigate the factors that affect spontaneous ignition. Based on the discussion and investigations, we find that it is more difficult for spontaneous ignition to occur in laboratory experiments than in oil reservoirs; spontaneous ignition is strongly affected by the initial reservoir temperature, oil activity, and heat loss; spontaneous ignition is only possible when the initial reservoir temperature is high, the oil oxidation rate is high, and the heat loss is low.

Support Materials of Organic and Inorganic Origin as Platforms for Horseradish Peroxidase Immobilization: Comparison Study for High Stability and Activity Recovery.

In the presented study, a variety of hybrid and single nanomaterials of various origins were tested as novel platforms for horseradish peroxidase immobilization. A thorough characterization was performed to establish the suitability of the support materials for immobilization, as well as the activity and stability retention of the biocatalysts, which were analyzed and discussed. The physicochemical characterization of the obtained systems proved successful enzyme deposition on all the presented materials. The immobilization of horseradish peroxidase on all the tested supports occurred with an efficiency above 70%. However, for multi-walled carbon nanotubes and hybrids made of chitosan, magnetic nanoparticles, and selenium ions, it reached up to 90%. For these materials, the immobilization yield exceeded 80%, resulting in high amounts of immobilized enzymes. The produced system showed the same optimal pH and temperature conditions as free enzymes; however, over a wider range of conditions, the immobilized enzymes showed activity of over 50%. Finally, a reusability study and storage stability tests showed that horseradish peroxidase immobilized on a hybrid made of chitosan, magnetic nanoparticles, and selenium ions retained around 80% of its initial activity after 10 repeated catalytic cycles and after 20 days of storage. Of all the tested materials, the most favorable for immobilization was the above-mentioned chitosan-based hybrid material. The selenium additive present in the discussed material gives it supplementary properties that increase the immobilization yield of the enzyme and improve enzyme stability. The obtained results confirm the applicability of these nanomaterials as useful platforms for enzyme immobilization in the contemplation of the structural stability of an enzyme and the high catalytic activity of fabricated biocatalysts.

Culture on the move

Nowadays, transformations of cultures and languages are increasingly noticeable due to heightened international mobility and intensified global communication and information flows. How such transformations play out and are met in Swedish education is a pressing topic to address to ensure relevant and inclusive quality education for all. The theme of this special issue, Culture on the Move, foregrounds language and literature both as pedagogical tools and disciplinary fields necessary for learning to live and work in a culturally diverse world. The contributions stem from the initial activities within the graduate school “Culturally Empowering Education through Language and Literature” (CuEEd-LL). Centre-staging teaching and learning in Swedish education, the articles in this issue present a range of inroads into how language and literature can be used to support cultural diversity among pupils, students and teachers since cultural diversity is steadily gaining attention both as a resource and a challenge in education and society.

Combining Intraoperative Electrocochleography with Robotics-Assisted Electrode Array Insertion.

To describe the use of robotics-assisted electrode array (EA) insertion combined with intraoperative electrocochleography (ECochG) in hearing preservation cochlear implant surgery. Prospective, single-arm, open-label study. All procedures and data collection were performed at a single tertiary referral center. Twenty-one postlingually deaf adult subjects meeting Food and Drug Administration indication criteria for cochlear implantation with residual acoustic hearing defined as thresholds no worse than 65 dB at 125, 250, and 500 Hz. All patients underwent standard-of-care unilateral cochlear implant surgery using a single-use robotics-assisted EA insertion device and concurrent intraoperative ECochG. Postoperative pure-tone average over 125, 250, and 500 Hz measured at initial activation and subsequent intervals up to 1 year afterward. Twenty-two EAs were implanted with a single-use robotics-assisted insertion device and simultaneous intraoperative ECochG. Fine control over robotic insertion kinetics could be applied in response to changes in ECochG signal. Patients had stable pure-tone averages after activation with normal impedance and neural telemetry responses. Combining robotics-assisted EA insertion with intraoperative ECochG is a feasible technique when performing hearing preservation implant surgery. This combined approach may provide the surgeon a means to overcome the limitations of manual insertion and respond to cochlear feedback in real-time.

Evaluation of Tungsten Catalysis among Early Transition Metals for N-Aryl-2,3,4,5-tetraarylpyrrole Synthesis: Modular Access to N-Doped π-Conjugated Material Precursors.

Low-valent tungsten species generated from WCl6 and N,N'-bis(trimethylsilyl)-2,5-dimethyldihydropyrazine (Si-Me2-DHP) promotes the catalytic formation of N-phenyl-2,3,4,5-tetraarylpyrroles 3aa-ka from diarylacetylenes 1a-k and azobenzene (2a). An initial catalyst activation process is a three-electron reduction of WCl6 with Si-Me2-DHP to afford transient 'WCl3' species. Catalytically active bis(imido)tungsten(VI) species via successive one-electron reduction and N═N bond cleavage of 2a was revealed by isolating W(═NPh)2Cl2(PMe2Ph)2 from imidotungsten(V) trichloride and 2a in the presence of PMe2Ph. The superior catalytic activity of the tungsten catalyst was clarified by a density functional theory study: activation energies for the key three steps, [2 + 2]-cycloaddition of W═NPh and diarylacetylene to form (iminoalkylidene)tungsten species, enyne metathesis with second diarylacetylene, and C-N bond formation, are reasonable values for the catalytic reaction at 180 °C. In addition, this tungsten catalyst overcame two distinct deactivation processes: α-enediamido formation and aggregation of the low-valent species, both of which were observed for previously developed vanadium and titanium catalysts. We also demonstrated the synthetic utility of pentaarylpyrroles 3aa and 3ba as well as N-(2-bromophenyl)-2,3,4,5-tetraarylpyrrole 3ab by derivatizing their π-conjugated compounds 9aa, 10ba, and 11ab.

Implementing adaptive e-learning for newborn care in Tanzania: an observational study of provider engagement and knowledge gains

IntroductionTo improve healthcare provider knowledge of Tanzanian newborn care guidelines, we developed adaptive Essential and Sick Newborn Care (aESNC), an adaptive e-learning environment. The objectives of this study were to...

Construction of a Cu@hollow TS‐1 nanoreactor based on a hierarchical full‐spectrum solar light utilization strategy for photothermal synergistic artificial photosynthesis

AbstractThe artificial photosynthesis technology has been recognized as a promising solution for CO2 utilization. Photothermal catalysis has been proposed as a novel strategy to promote the efficiency of artificial photosynthesis by coupling both photochemistry and thermochemistry. However, strategies for maximizing the use of solar spectra with different frequencies in photothermal catalysis are urgently needed. Here, a hierarchical full‐spectrum solar light utilization strategy is proposed. Based on this strategy, a Cu@hollow titanium silicalite‐1 zeolite (TS‐1) nanoreactor with spatially separated photo/thermal catalytic sites is designed to realize high‐efficiency photothermal catalytic artificial photosynthesis. The space–time yield of alcohol products over the optimal catalyst reached 64.4 μmol g−1 h−1, with the selectivity of CH3CH2OH of 69.5%. This rationally designed hierarchical utilization strategy for solar light can be summarized as follows: (1) high‐energy ultraviolet light is utilized to drive the initial and difficult CO2 activation step on the TS‐1 shell; (2) visible light can induce the localized surface plasmon resonance effect on plasmonic Cu to generate hot electrons for H2O dissociation and subsequent reaction steps; and (3) low‐energy near‐infrared light is converted into heat by the simulated greenhouse effect by cavities to accelerate the carrier dynamics. This work provides some scientific and experimental bases for research on novel, highly efficient photothermal catalysts for artificial photosynthesis.

New insights on the application of half‐sandwich complexes with metal–iodide bonds for agricultural fungicides

Cyclopentadienyl half‐sandwich complexes of cobalt and iron with metal–iodide bonds were reported to efficiently inhibit the growth of phytopathogenic fungi. With the aim of investigating the structure/activity relationships, further in vitro experiments were carried out. Cyclic voltammetric characterization, chemical stability, and antiradical activity were performed in two solvents: dimethyl sulfoxide and acetone. The iodide ion removal from the complex appears to be the key point of antifungal activity. Moreover, a preliminary cell viability test on human keratinocytes was also assessed in order to verify the nontoxic effect of tested compounds. The cytotoxicity for all the complexes was comparable with that shown by povidone iodide, a common antifungal agent recognized as safe (IC50 > 300 mM). Furthermore, the work proposes an additional roadmap (sequence of experiments) at the initial antifungal activity tests, which improves insight into their mechanism of action.

Anatomically Based Ablation of Left Ventricular Summit Premature Ventricular Complexes Guided by Intracardiac Echocardiography.

Catheter ablation of premature ventricular contractions (PVCs) arising from the left ventricular summit (LVS) presents technical challenges due to the regional anatomy and frequent intramural site of origin (SOO). Intracardiac echocardiography (ICE) and the CARTOSOUND® (Biosense Webster, Diamond Bar, CA, USA) module allow the operator to directly reconstruct and visualize the dimensions and orientation of the LVS live and present it in relation to neighboring structures. We retrospectively reviewed consecutive cases between January 2021 and December 2022 of patients undergoing PVC ablation for a presumed LVS origin. The LVS was reconstructed by creating a three-dimensional representation of the left ventricular septum, using two-dimensional ICE sections. The earliest site in each chamber was tagged on the reconstructed LVS, and the presumed SOO was localized using a geometrical center point from all sites. Ablation was first delivered to the earliest site, except when the presence of coronary branches precluded radiofrequency delivery within the great cardiac vein. Of 20 patients (8 women, 62.4 ± 7.1 years old) with a presumed LVS origin, 12 had PVC recurrence within the monitoring period after the initial ablation for 192.5 ± 37.2 s at the earliest site. Among them, earliest activation was seen at the sinus of Valsalva (SoV), coronary venous system (CVS), and left ventricular endocardium (LVE) in four, six, and two patients, respectively. Using the reconstructed LVS, the anatomically closest site to the SOO was identified in the SoV, CVS, and LVE in four, two, and six cases, respectively. Throughout the study period (14.5 months; range, 9.3-19.7 months), 17 patients (85%) had complete elimination of PVCs as evaluated by 24-h event monitors at the 12-month visit. In 50% of cases, among patients in whom ablation at the earliest signal was unsuccessful, the site of successful ablation did not correlate with the second earliest signal or had no identifiable signal during initial activation mapping. The reconstructed LVS not only guided activation mapping but also identified sites proximal to the center point that had either a late activation signal, a low-amplitude signal, or no signal at all.

Diastereoselective synthesis of cis‐1,2‐limonene oxide using dimeric Salen‐Mn (III) complexes as reusable catalysts

Diastereoselective epoxidation of R‐(+)‐limonene using achiral and racemic dimeric Salen‐Mn (III) complexes as catalysts ((1a) and (1b)) and in situ generated dimethyldioxirane (DMDO) as an oxidizing agent was explored. The best reaction parameters were: (i) KHSO5/R‐(+)‐limonene molar ratio = 0.25; (ii) R‐(+)‐limonene, catalyst molar ratio = 20, (iii) absence of nitrogenous bases (axial ligands), (iv) ambient temperature (20°C), (v) racemic dimeric catalyst, and (vi) low amount of acetone (4 mL). Under these reaction conditions isolated yield to 1,2‐(+)‐limonene oxide and diastereomeric excess (d.e), and diastereomeric yield excess (d.y.e) to major diastereomer (cis‐epoxide) was 96%, 77%, and 72%, respectively. Moreover, the catalyst was segregated into a solid phase, while products remained in the liquid phase, allowing the easy separation of the catalyst and reaction products. Consequently, the catalyst could be recycled up to three times without appreciable loss of its initial catalytic activity.

Deciphering orbital hybridization in heterogeneous catalysis

AbstractThe catalytic coordinate is essentially the evolving frontier orbital interaction while feeding with catalytic materials and adsorbates under proper reaction conditions. The heterogeneous catalytic reaction mechanism involves the initial adsorption and activation of reactants, subsequent intermediate transformation, final target product desorption, and regeneration of catalytic materials. In these catalytic processes, interaction modulations in terms of orbital hybridization/coupling allow an intrinsic control on both thermodynamics and kinetics. Concerned charge transfer and redistribution, orbital splitting and rearrangement with specific orientation, and spin change and crossover pose a formidable challenge on mechanism elucidation; it is hard to precisely correlate the apparent activity and selectivity, let alone rational modulations on it. Therefore, deciphering the orbital couplings inside a catalytic round is highly desirable and the dependent descriptor further provides in‐depth insights into catalyst design at the molecule orbital level. This review hopes to provide a comprehensive understanding on orbital hybridizations, modulations, and correlated descriptors in heterogeneous catalysis.

Combined cross-linking of Rhizomucor miehei lipase and Candida antarctica lipase B for the effective enrichment of omega-3 fatty acids in fish oil

The incorporation of a non-specific lipase and a sn-1,3 specific one in a single immobilized system can be a promising approach for the exploitation of both lipases. A one-step immobilization platform mediated by an isocyanide-based multi-component reaction was applied to create co-cross-linked enzymes (co-CLEs) of lipases from Rhizomucor miehei (sn-1,3 specific) and Candida antarctica (non-specific). Glutaraldehyde was found to be effective cross-linker by producing specific activity of 16.9 U/mg and immobilization yield of 99 %. High activity recovery of up to 404 % was obtained for immobilized derivatives. Leaking experiment showed covalent nature of the cross-linking processes. BSA had considerable effect on the immobilization process, providing 87–100 % immobilization yields and up to 10 times improvement in the specific activity of the immobilized derivatives. Scanning electron microscopy images showed flower-like and rod-like structures for the CLEs prepared by glutaraldehyde and undecanedicarboxylic acid, respectively. The prepared co-CLEs were examined in non-selective enrichment of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil, showing capability of releasing up to 100 % of both omega-3 fatty acids within 8 h of the reaction. The reusability of co-CLEs in five successive cycles presented retaining 63–72 % of their initial activities after the fifth reuse cycle in the hydrolysis reaction.

Mechanically stirred enzymatic membrane reactor containing HRP immobilized on Tau-SiO2@Fe3O4-GO nanocomposite for removal of tetracycline in synthetically concocted wastewater.

The process of mechanically stirred membrane reactor containing the suspension of horseradish peroxidase (HRP) immobilized on synthesized nanocomposite (Tau-SiO2@Fe3O4-GO) was designed for continuous degradation of tetracycline. The immobilized HRP was characterized in terms of kinetic parameters and catalytic activities as these parameters were improved highly through immobilization. The stability indices including pH and temperature were investigated in parallel. The immobilized HRP was more tolerable to pH changes as compared to free HRP and the optimum temperature obtained at 40°C. The reusability of HRP was promoted by immobilization as far as 70% of initial activity after ten cycles. The enzymatic degradation of optimum concentration of tetracycline was carried out in batch condition and 100% of tetracycline removed after 30min. The results also showed that higher concentration of H2O2 exhibited more oxidation of tetracycline. The optimal ratio of HRP/H2O2 was also obtained at 0.005. The simultaneous process including separation and the biocatalytic degradation established in the membrane stirrer reactor concluded that no amount of tetracycline was observed in the permeate stream coming from the membrane after 30min of operation.

Interaction of designed cationic antimicrobial peptides with the outer membrane of gram-negative bacteria

The outer membrane (OM) is a hallmark feature of gram-negative bacteria that provides the species with heightened resistance against antibiotic threats while cationic antimicrobial peptides (CAPs) are natural antibiotics broadly recognized for their ability to disrupt bacterial membranes. It has been well-established that lipopolysaccharides present on the OM are among major targets of CAP activity against gram-negative species. Here we investigate how the relative distribution of charged residues along the primary peptide sequence, in conjunction with its overall hydrophobicity, affects such peptide-OM interactions in the natural CAP Ponericin W1. Using a designed peptide library derived from Ponericin W1, we determined that the consecutive placement of Lys residues at the peptide N- or C-terminus (ex. “PonN”: KKKKKKWLGSALIGALLPSVVGLFQ) enhances peptide binding affinity to OM lipopolysaccharides compared to constructs where Lys residues are interspersed throughout the primary sequence (ex. “PonAmp”: WLKKALKIGAKLLPSVVKLFKGSGQ). Antimicrobial activity against multidrug resistant strains of Pseudomonas aeruginosa was similarly found to be highest among Lys-clustered sequences. Our findings suggest that while native Ponericin W1 exerts its initial activity at the OM, Lys-clustering may be a promising means to enhance potency towards this interface, thereby augmenting peptide entry and activity at the IM, with apparent advantage against multidrug-resistant species.

Mechanism of initial activation of carbon–oxygen bonds for deoxidation of acetic acid

Producing valuable fuel-ranged hydrocarbons from cellulosic biomass is an effective approach to addressing potential energy issues. However, the cellulose-derived bio-oil may contain carboxylic acid components that contribute to the unfavorable acidic and corrosive nature, which necessitates upgrading through the hydrodeoxygenation (HDO) treatment using heterogeneous catalysis. Here, we performed reactive force-field molecular dynamics (ReaxFF-MD) to study the hydrogenolysis, dehydrogenation and decarboxylation mechanisms of the acetic acid model compound on the Ni-based catalyst. Comparative analysis of the activation of C–O and C=O bonds was presented, followed by an examination of the associative desorption of H2 and the dynamic evolution of main intermediates. Furthermore, the conversion pathways of key intermediates were determined and four main pathways for ethanol generation and the temperature-response mechanism for coking formation were proposed. This mechanism diagram explains the strong effects of a hydrogen environment in biomass-related reactions, highlighting the dynamic mechanism of selective hydrogenation and deoxygenation of carbon–oxygen bonds.