Stability Limit Research Articles

A polyethylene glycol derivatized laccase with improved thermal resistance

Laccases are versatile and relatively accessible catalysts with practical/industrial applications. Their protein structure entails limited stability under non-native conditions, especially such as those that would be required for industrial applications. Here, the derivatization of a laccase from Sclerotinia sclerotiorum is reported, using a (methyl-PEG12)3-PEG4)-N-succinimide ester – known as trimethyl-PEG-NHS or shortly TMS(PEG)12 – to improve the thermostability of the enzyme. PEGylated versions of the laccase are characterized by gel electrophoresis, size-exclusion chromatography, catalytic parameters, and thermal stability. A protocol for PEGylation is identified, that allows for a 50% increase in residual activity for the PEGylated laccase compared to the native enzyme, when the activity is tested after incubation at 50 °C for up to two hours.

Impact of cognitive fatigue on balance in individuals with multiple sclerosis without cognitive impairment

ABSTRACT Purpose This study aims to examine the impact of cognitive fatigue on balance among individuals with multiple sclerosis (MS) without cognitive impairment. Method A total 50 individuals with MS aged 20–50 years, without cognitive impairment and with an Expanded Disability Status Scale (EDSS) score of 0–4, participated in the study. Participants were randomly assigned to either a control group (CG) or a study group (SG). The CG rested for 30 minutes, while the SG engaged in cognitive activities lasting 30–45 minutes to induce cognitive fatigue. Cognitive fatigue was assessed using the Visual Analog Scale (VAS) before and after the tasks. Balance was evaluated using clinical tests: the Functional Reach Test (FRT) and the Single Leg Stance Test (SLST), as well as laboratory assessments including the Modified Clinical Test of Sensory Integration and Balance (mCTSIB) and Limits of Stability (LOS) with static posturography. Results Within-group analyses showed a significant increase in cognitive fatigue on the VAS in the SG (p < 0.001). In the mCTSIB, the SG showed significant changes in firm/eyes open, foam/eyes open, and composite scores, while between-group differences were observed only in firm/eyes open and foam/eyes open conditions (p < 0.005). No significant differences were found between groups in LOS, FRT, or SLST outcomes (p > 0.05). Conclusion In individuals with MS, the impact observed only in the eyes-open static balance condition suggests that dynamic balance and eyes-closed static balance parameters rely more on automatic mechanisms compared to the eyes-open condition and are not influenced by cognitive fatigue.

Enzymatic Synthesis of Bioactive Structured DHA Phospholipids via Stable Immobilized Phospholipase-Catalyzed Esterification in a Solvent-Free Medium

The enzymatic esterification of docosahexaenoic acid (DHA) with glycerophosphocholine (GPC) was investigated to produce bioactive structured DHA phospholipids with DHA esterified at the sn-2 position, which may contribute to the prevention of neurodegenerative diseases such as Alzheimer’s. This reaction is complex due to the low solubility of GPC in anhydrous organic media and the limited stability of enzymes under such conditions. The immobilized phospholipase Quara® LowP (QlowP-C18) proved to be the most effective catalyst, achieving a 58% yield of di-substituted DHA phospholipids (Di-DHA-PC) in just 48 h under optimal conditions (solvent-free media at 60 °C) with 95% purity. Advanced immobilization and post-immobilization techniques significantly improved the stability of QlowP-C18, increasing its longevity threefold and enabling reuse for up to five reaction cycles at 40 °C. The total production reached 120.4 mg of highly pure DHA-di-substituted phospholipid. These findings highlight the effectiveness of stable immobilized enzymes in solvent-free systems and underscore their potential for the efficient and sustainable production of highly pure Di-DHA-PC, which could be used as a functional or nutraceutical ingredient for the prevention of neurodegenerative diseases.

Orbits of Six Triple Systems

Abstract Joint analysis of position measurements and radial velocities of six triple stellar systems is conducted to determine their inner and/or outer orbits. Accumulation of such data is needed to study the architecture of stellar hierarchies and its relation to the formation mechanisms. The inner periods in the six systems (HIP 11783, 64836, 72423, 84720, 89234, and 105404) range from 0.5 days to 44 yr. The shortest outer period of 3.34 yr is found in the compact triple HIP 105404 (BS Ind). The resolved triple system HIP 64836 has comparable inner and outer periods (5 and 30 yr), placing it near the limit of dynamical stability, while its quasi-circular and coplanar orbits suggest a 1:6 mean motion resonance. The periods in HIP 89234 (44 and ~450 yr) are also comparable, but the mutual orbit inclination is large, 54°. Masses of the components are estimated and each system is discussed individually.

Detection of Eclipses in the Cataclysmic Variable LAMOST J035913.61 + 405035.0

ABSTRACTI conducted photometric observations of the cataclysmic variable LAMOST J035913.61 + 405035.0 and detected eclipses. During these observations, I recorded 14 eclipses over two groups of nights separated by 13 months. I accurately determined the orbital period of the system to be days. For the eclipses, I derived an ephemeris which is valid for a long time and suitable for studying changes in the orbital period. The out‐of‐eclipse magnitude of the star varied between 15.32 ± 0.02 and 17.25 ± 0.08 mag. As the brightness decreased, the eclipses became deeper and narrower. The average depth of eclipses was 1.35 ± 0.10 mag, and the average width at half‐depth was 16.9 ± 0.7 min. I estimated the range of possible orbital inclinations to be between 72.8° and 76.0°, and the range of average absolute V‐band magnitudes of the disc to be between 5.16 ± 0.15 and 5.44 ± 0.15 mag. Although based on the light curve from the ZTF survey, LAMOST J035913.61 + 405035.0 showed only small outbursts with amplitudes below 1.5 mag, it should be classified as a dwarf nova because the average disc brightness and mass transfer rate were below the limit of thermal instability.

Graphene-based materials and electrochemical biosensors: An overview.

Graphene, an exceptional two-dimensional material, has attracted significant attention from the scientific community. Its unique physiochemical properties make it a suitable candidate for many applications in the field of biotechnology and medical sciences. High specific surface area, exceptionally high electrical conductivity, and good biocompatibility of graphene give it a large scope in disease diagnosis and biosensing applications. This review aims at presenting the advances in the journey of graphene-based materials and their successful implication as electrochemical nanobiosensors. The first part of the review summarizes the history, structure, and recent developments in the large-scale production of graphene. It further includes the sensing mechanism, the recent trends in biosensing, and improvements in graphene-based biosensors. The comparative analysis shows graphene-based electrochemical biosensors to have high sensitivity, long-term stability, and low detection limits compared to the various other biosensors.&#xD.

From Salt in Water, Water in Salt to Beyond.

Traditional aqueous electrolytes have a limited electrochemical stability window due to the decomposition voltage of water (≈1.23V). "Water-in-Salt" (WIS) electrolytes are developed, which expand the stability window of aqueous electrolytes from 1.23 to 3V and sparked a global surge of research in aqueous batteries. This breakthrough revealed novel aspects of solvation structure, ion transport mechanisms, and interfacial properties in WIS electrolytes, marking the start of a new era in solution chemistry that extends beyond traditional dilute electrolytes and has implications across electrolyte research. In this review, the current mechanistic understanding of WIS electrolytes and their derivative designs, focusing on the construction of solvation structures is presented. The insights gained and limitations encountered in bulk solvation structure engineering is further discussed. Finally, future directions beyond WIS for advancing aqueous electrolyte design is proposed.

Unveiling the Potential of a Cobalt‐Based Metal‐Organic Framework in Carbodiimide Synthesis

The synthesis of carbodiimides via nitrene transfer to isocyanides has garnered significant attention in recent years. However, this reaction predominantly relies on homogeneous catalytic systems with high catalyst loadings. In this study, we employed ZIF‐67 MOF as a heterogeneous catalyst for carbodiimide synthesis and conducted an in‐depth analysis of its stability. Our findings reveal the non‐innocent role of catalyst leaching, demonstrating that even as little as 0.04 mol% of leached cobalt species is sufficient to catalyze this reaction. This result is in contrast with previous reports, where 5–10 mol% of cobalt‐loading is required. Furthermore, this study highlights that lower catalyst loadings are more efficient, particularly in cases where isocyanides exhibit limited stability.

Whole-Body Vibration Without Visual Feedback on Postural Steadiness in Unilateral Trans-Femoral Traumatic Amputees: A Randomized Controlled Trial.

Unilateral traumatic trans-femoral amputees exhibit a higher incidence of falling and become physically asymmetrical because the side that was amputated has different feelings and less muscle. To explore the impact of Whole-body vibration Without Visual Feedback (VFDWBV) on postural steadiness in unilateral traumatic trans- femoral amputees. A double-blinded randomized controlled study of technology and information was conducted at a modern university. A total of 108 individuals, 40-55years who had experienced a traumatic amputation of one leg above the knee were divided into three groups: group A received whole body vibration (WBV) with their eyes opened, group B received (VFDWBV), and group C received conservative treatment only. The stability of the prosthetic leg, stability limit, and sway index (m-CTSIB) were assessed at the beginning and after 12weeks. Sessions occurred three times each week. Significant statistical differences were seen in the stability of prosthetic legs, the limit of stability, and (m-CTSIB) between groups A and B, considering the treatment interaction (F=24.8, p=0.001). Additionally, the group receiving VFDWBV showed a more significant improvement in postural steadiness than those receiving WBV and the control group. Utilizing VFDWBV at a frequency of 30 HZ can significantly enhance the stability of posture in individuals with unilateral traumatic trans-femoral amputations. The study was registered with the Clinical Trials.gov (NCT06284733).

Exploring Latest Expansions in Solid Lipid-based Nanoparticle Technology for Treatment of Cancer.

The field of cancer therapy has witnessed significant strides with the emergence of innovative drug delivery systems and one such promising avenue is solid lipid-based nanoparticle (SLN) technology. This abstract provides a complete overview of current advances in developing SLNs for effective cancer treatment solid lipid nanoparticles (NPs) represent a novel drug delivery platform characterized by their unique composition which includes biocompatible lipids as the main carrier material. This technology addresses challenges related to standard chemotherapy such as low bioavailability limited medicine stability and non-specific targeting. The incorporation of lipids in SLNs ensures enhanced drug encapsulation, protection of therapeutic agents from degradation-controlled release profiles. Recent breakthroughs in SLN technology have focused on optimizing formulation parameters to achieve superior drug loading capacities stability and sustained release kinetics. Advanced fabrication techniques including high-pressure homogenization and microemulsion methods have been pivotal in tailoring SLN properties for specific cancer types and therapeutic agents. Furthermore, SLNs' capacity to passively build up in tumor tissues using increased penetration and retention effects has been harnessed for targeted drug transport. Surface modifications using ligands or antibodies to facilitate active targeting, enhancing medication delivery's selectivity to tumor cells decreasing unwanted effects on normal tissues. This abstract highlights recent preclinical and clinical studies demonstrating the efficacy of SLN-based formulations in enhancing the therapeutic outcomes of various anticancer agents. The versatile nature of SLN technology makes it a viable option for the advancement of personalized and precision cancer therapies, marking a significant stride toward overcoming the limitations of conventional cancer treatments. As research in this domain progresses, the integration of SLNs holds immense potential for revolutionizing tumor treatment strategies.

The Role of Bioactive Glasses in Modern Dentistry: From Remineralization to Regeneration

Aim: This review explores the potential of bioactive glasses in dentistry, focusing on their applications in dental restorations, implants, and tissue regeneration. The aim is to assess the challenges and opportunities in their use, as well as the future directions for enhancing their performance. Materials and Methods: A comprehensive review of recent literature was conducted to analyze the properties, applications, and limitations of bioactive glasses in dental materials. Studies on the composition, mechanical properties, biocompatibility, and long-term in vivo performance were included. Methods to enhance the mechanical strength of bioactive glasses, such as the formation of composites and advanced nano structuring, were also explored. Results: Bioactive glasses have shown great promise in promoting remineralization, supporting tissue regeneration, and bonding with hard tissues. However, challenges such as mechanical brittleness, high costs, and limited long-term stability have been identified. Research on enhancing mechanical strength through composites, as well as developing more cost-effective production methods, is ongoing. Conclusion: Bioactive glasses offer significant potential for improving dental treatments and advancing regenerative medicine. Future research should focus on enhancing their mechanical properties, developing personalized bioactive materials, and exploring their integration with stem cell therapies and growth factors. With continued development, bioactive glasses could revolutionize dental restorations, implants, and oral tissue regeneration, providing innovative solutions for oral healthcare.

Rigid Polyurethane Foam Derived from Renewable Sources: Research Progress, Property Enhancement, and Future Prospects

Rigid polyurethane foam (RPUF) is a widely utilized thermosetting polymer across various industrial applications, valued for its exceptional properties. However, the demand for sustainable alternatives to petroleum-based polymers has grown increasingly urgent due to rising environmental concerns. Despite its widespread use, RPUF faces challenges such as inadequate mechanical strength, limited thermal stability, and high flammability, all of which are crucial considerations in commercial and household applications. Globally, ongoing efforts are focused on developing innovative technologies that convert renewable sources into new monomers and polymers, some of which could serve as alternatives to traditional RPUFs. Several approaches have been explored to improve the thermal stability, mechanical strength, and flame retardancy of RPUFs, including the modification of bio-based polyols and the incorporation of performance-enhancing fillers. This review emphasizes recent advances in RPUFs derived from natural resources, focusing on their preparation, characterization, and properties, and strategies to enhance the mechanical strength and flame safety of bio-based RPUFs. Additionally, it explores the applications of RPUF materials across various fields, addressing the challenges and potential developments in packaging, household items, construction, and automotive applications.

New Standardized Procedure to Extract Glyphosate and Aminomethylphosphonic Acid from Different Matrices: A Kit for HPLC-UV Detection

Background: Glyphosate has been extensively used as herbicide since the early 1970s. The daily exposure limit is set at 0.3 mg/kg bw/d in Europe and 1.75 mg/kg bw/d in the USA. Among its derivatives, aminomethylphosphonic acid is the most stable and abundant. Understanding their biological effects then requires reliable methods for quantification in biological samples. Methods: We developed and validated a fast, low-cost, and reliable chromatographic method for determining glyphosate and aminomethylphosphonic acid concentrations. The validation included following parameters: specificity, selectivity, matrix effect, accuracy, precision, calibration performance, limit of quantification, recovery, and stability. Sample extraction employed an anion exchange resin with elution using hydrochloric acid 50.0 mmol/L. For HPLC analysis, analytes were derivatized, separated on a C18 column with a mobile phase of phosphate buffer (0.20 mol/L, pH 3.0) and acetonitrile (85:15), and detected at 240 nm. Results: The method demonstrated high reliability and reproducibility across various matrices. Its performance met all validation criteria, confirming its suitability for quantifying glyphosate and aminomethylphosphonic acid in different biological and experimental setups. Conclusions: This method can offer a practical resource for applications in experimental research, medical diagnostics, quality control, and food safety.

Enhancing the Performance of Nanocrystalline Nickel Cathodes via Electrodeposition for Use in Ni-Zn Batteries: Morphological and Crystallographic Structure Optimization

Rechargeable Ni-Zn batteries are gaining interest owing to their adequate performance for achieving net-zero carbon goals, low cost, and safety. However, the nickel electrodes still face significant challenges due to its limited stability and low capacity. This study investigates the development and comparison of different nickel morphologies produced by electrodeposition techniques. Ni nanocrystalline coatings with different surface morphologies were successfully electrodeposited using direct (DC), pulsed (PC), and pulsed reverse (PRC) current techniques and their physical and electrochemical properties of were investigated. Notably, the electrodeposition method significantly impacted the morphology and electrochemical performance of the prepared Ni coatings. Among the obtained structures, the PRC-deposited coating displayed a unique nano-rod like morphology, exceptional uniformity, highest surface oxygen content (61.51%), and lowest surface roughness (5.12 nm). Furthermore, electrochemical measurements revealed that this structure possesses the lowest coating resistance (459.6 Ω.cm−1), minimal corrosion potential (5 mV vs SCE), enhanced oxidation/reduction peaks, the longest charge/discharge time, and highest discharge (26.2 mF.cm−2) areal capacity. These findings suggest that the Ni nanorod structure exhibits superior surface and electrochemical properties. This work offers valuable insights into how morphology and structure affect the electrochemical performance and capacity of nickel electrodes, advancing battery technologies.

Co doped V2O5 hollow microsphere as high-performance cathode for aqueous zinc-ion battery

Co doped V2O5 hollow microsphere as high-performance cathode for aqueous zinc-ion battery

Directing mineralization of ZnO nanoparticles in cyanobacterial liquid crystalline polysaccharides for cancer therapies.

Effective cancer therapy faces significant challenges, including non-selective toxicity, limited structural stability, inconsistent nanoparticle (NP) morphology, and instability under varying biological conditions. These issues hindering targeted delivery and therapeutic efficacy. Previous approaches using polysaccharide-based nanomaterials have shown promise; however, problems such as inconsistent NP sizes and shapes, poor mechanical stability, and limited pH resilience restrict their clinical potential. This study hypothesized that sacran, a cyanobacterial liquid crystalline (LC) polysaccharide, can stabilize ZnO NPs, allowing for controlled mineralization, enhanced stability, and selective cytotoxicity. We developed ZnO nanocomposite xerogels in an LC sacran matrix, yielding block-like ZnO NPs (25-70 nm) with high surface-area-to-volume ratios that improve cellular uptake in tumor environments. Incorporating these NPs into chemically crosslinked sacran matrices resulted in a 3-fold increase in mechanical strength and a 10-fold improvement in swelling capacity compared to physically crosslinked systems. Additionally, the sacran-ZnO nanocomposites demonstrated robust stability under various pH conditions, indicating their resilience in diverse biological environments. Cytotoxicity assays revealed that higher concentrations of ZnO NP selectively increased toxicity toward human lung cancer cells (A549), with less impact on human dermal fibroblasts (HDFa). Moreover, HDFa successfully attached to and proliferated on the smooth surfaces of the xerogels, emphasizing their compatibility with normal cells. This highlights the potential of sacran-ZnO nanocomposite xerogels as cancer-selective therapeutic materials, offering stability and effectiveness even under varying biological conditions, while addressing key challenges associated with earlier NP-based therapies.

A Comprehensive Review of Challenges in Oral Drug Delivery Systems and Recent Advancements in Innovative Design Strategies.

The oral route of drug administration is often preferred by patients and healthcare providers due to its convenience, ease of use, non-invasiveness, and patient acceptance. However, traditional oral dosage forms have several limitations, including low bioavailability, limited drug loading capacity, and stability and storage issues, particularly with solutions and suspensions. Over the years, researchers have dedicated considerable effort to developing novel oral drug delivery systems to overcome these limitations. This review discusses various challenges associated with oral drug delivery systems, including biological, pharmaceutical, and physicochemical barriers. It also explores common delivery approaches, such as gastroretentive drug delivery, small intestine drug delivery, and colon-targeting drug delivery systems. Additionally, numerous strategies aimed at improving oral drug delivery efficiency are reviewed, including solid dispersion, absorption enhancers, lipidbased formulations, nanoparticles, polymer-based nanocarriers, liposomal formulations, microencapsulation, and micellar formulations. Furthermore, innovative approaches like orally disintegrating tablets (ODT), orally disintegrating films (ODF), layered tablets, micro particulates, self-nano emulsifying formulations (SNEF), and controlled release dosage forms are explored for their potential in enhancing oral drug delivery efficiency and promoting patients' compliance. Overall, this review highlights significant progress in addressing challenges in the pharmaceutical industry and clinical settings, offering novel approaches for the development of effective oral drug delivery systems.

Polysaccharide-based biomaterials for regenerative therapy in intervertebral disc degeneration.

Intervertebral disc (IVD) degeneration represents a significant cause of chronic back pain and disability, with a substantial impact on the quality of life. Conventional therapeutic modalities frequently address the symptoms rather than the underlying etiology, underscoring the necessity for regenerative therapies that restore disc function. Polysaccharide-based materials, such as hyaluronic acid, alginate, chitosan, and chondroitin sulfate, have emerged as promising candidates for intervertebral disc degeneration (IVDD) therapy due to their biocompatibility, biodegradability, and ability to mimic the native extracellular matrix (ECM) of the nucleus pulposus (NP). These materials have demonstrated the capacity to support cell viability, facilitate matrix production, and alleviate inflammation in vitro and in vivo, thus supporting tissue regeneration and restoring disc function in comparison to conventional treatment. Furthermore, polysaccharide-based hydrogels have demonstrated the potential to deliver bioactive molecules, including growth factors, cytokines and anti-inflammatory drugs, directly to the degenerated disc environment, thereby enhancing therapeutic outcomes. Therefore, polysaccharide-based materials provide structural support and facilitate the regeneration of native tissue, representing a versatile and effective approach for the treatment of IVDD. Despite their promise, challenges such as limited long-term stability, potential immunogenicity, and the difficulty in scaling up production for clinical use remain. This review delineates the potential of various polysaccharides during the fabrication of hydrogels and scaffolds for disc regeneration, guiding and inspiring future research to focus on optimizing these materials for clinical translation for IVDD repair and regeneration.

Molybdenum disulfide nanosheets hybridized with lysine molecules for highly efficient near-infrared photothermal energy conversion

Molybdenum disulfide nanosheets hybridized with lysine molecules for highly efficient near-infrared photothermal energy conversion

Blowout and stability limits of ammonia-hydrogen-nitrogen/air flames in non-premixed coaxial swirl combustor with varying ammonia fraction

Blowout and stability limits of ammonia-hydrogen-nitrogen/air flames in non-premixed coaxial swirl combustor with varying ammonia fraction