Boosting sodium-ion battery performance with binary metal-doped Na3V2(PO4)2F3 cathodes

Na3V2(PO4)2F3 (NVPF), recognized for its Na superionic conductor architecture, emerges as a promising candidate among polyanion-type cathodes for sodium ion batteries (SIBs). However, its adoption in practical applications faces obstacles due to its inherently low electronic conductivity. To address this challenge, we employ a binary co-doped strategy to design Na3.3K0.2V1.5Mg0.5(PO4)2F3 cathode with nitrogen-doped carbon (NC) coating layer. This configuration enhances electronic conductivity and reduces diffusion barriers for sodium ion (Na+). The strategy of incorporating nitrogen-doped carbon coating not only facilitates the formation of a porous structure but also introduces additional defects and active sites. Such modifications accelerate the reaction kinetics and augment electrolyte interaction through an expanded specific surface area, thus streamlining the electrochemical process. Concurrently, strategic heteroatom substitution leads to a more efficient engagement of Na+ in the electrochemical activities, thereby bolstering the cathode's structural integrity. The vanadium fluorophosphate Na3.3K0.2V1.5Mg0.5(PO4)2F3@NC exhibits an electrochemical performance, including a high discharge specific capacity of 124.3 mA h g-1 at 0.1C, a long lifespan of 1000 cycles with a capacity retention of 93.1 % at 10C, and a rate property of 73.2 mA h g-1 at 20C. This research provides a method for preparing binary doped NVPF for energy storage electrochemistry.

Optimizing Mn in Prussian blue analogs with double redox active sites to induce boosted Zn2+ storage

Prussian Blue analogs (PBAs) are a suitable aqueous zinc-ion batteries (AZIBs) cathode material, but they face issues related to low specific capacity and cycling lifespan due to insufficient active sites and poor ion de-intercalation structural stability. In this study, Mn-Prussian Blue Analog (Mn-PBA) is fabricated using a simple co-precipitation method and the morphology of Mn-PBA is further optimized through artificially manipulating concentration gradients strategy, effectively enhancing the structural stability of Zn2+ de-intercalation. Furthermore, the introduction of Mn established dual Zn2+ active centers in Mn-PBA (Mn-O and Fe(CN)6]4-/[Fe(CN)6]3-), leading to an increased specific capacity. As a proof of concept for AZIBs, the optimized Mn-PBA-3 cathode exhibits a high reversible specific capacity of 143.5 mAh/g and maintains a capacity retention of 88.5 % after 250 cycles at 1 A/g, surpassing commercial MnO2 (30.5 mAh/g after 100 cycles). Mn-PBA-3 also delivers a high capacity of 79.0 mA h g-1 after 2000 cycles of 10 A/g. The mechanism of the Zn2+ double redox reaction of Mn-PBA-3 has been revealed in detail by in situ Raman and a series of ex situ techniques. Under a high operating voltage window of 0-1.9 V, Zn//Mn-PBA-3 demonstrates a capacity of 99.3 mAh/g after 800 cycles (5 A/g) by assembling zinc ion button battery. This work has reference significance for structurally modulated PBAs used in high performance AZIBs.

Stabilizing Ni-rich Single-crystalline LiNi0.83 Co0.07 Mn0.10 O2 Cathodes using Ce/Gd Co-doped High-entropy Composite Surfaces

Ni-rich layered oxides are promising lithium-ion batteries (LIBs) cathode materials for their high reversible capacity, but they suffer from fast structural degradation during cycling. Here, we report the Ce/Gd incorporated single-crystalline LiNi0.83 Co0.07 Mn0.10 O2 (SC-NCM) cathode materials with significantly enhanced cycling stability. The Gd ions are adequately incorporated in SC-NCM while Ce ions are prone to aggregate in the outer surface, resulting in the formation of a high-entropy zone in the near-surface of SC-NCM, including a Gd doped LiCeO2 (LCGO) shell and Ce/Gd dopant-concentrated layer. The high-entropy zone can effectively inhibit the oxygen evolution and prevent the formation of oxygen vacancies. Meanwhile, it leads to a greatly improved H2-H3 phase transformation reversibility and mitigated stress/strain caused by Li-ion extraction/insertion during (de)lithiation process. The synergetic effects of reduced oxygen vacancies concentration and mitigated stress/strain can effectively prevent the in-plane migration of TM ions, lattice planar gliding as well as the formation of intragranular nanocracks. Consequently, Ce/Gd incorporated SC-NCM (SC-NCM@CG2) delivers a high initial discharge specific capacity of 219.7 mAh g-1 at 0.1 C and an excellent cycling stability with a capacity retention of 90.2 % after 100 cycles at 1.0 C.

Cataract-related variant R114C increases βA3-crystallin susceptibility to environmental stresses by disrupting the protein senior structure

Congenital cataract is a major cause of childhood blindness worldwide, with crystallin mutations accounting for over 40 % of gene-mutation-related cases. Our research focused on a novel R114C mutation in a Chinese family, resulting in bilateral coronary cataract with blue punctate opacity. Spectroscopic experiments revealed that βA3-R114C significantly altered the senior structure, exhibiting aggregation, and reduced solubility at physiological temperature. The mutant also displayed decreased resistance and stability under environmental stresses such as UV irradiation, oxidative stress, and heat. Further, cellular models confirmed its heightened sensitivity to environmental stresses. These data suggest that the R114C mutation impairs the hydrogen bond network and structural stability of βA3-crystallin, particularly at the boundary of the second Greek-key motif. This study revealed the pathological mechanism of βA3-R114C and may help in the development of potential treatment strategies for related cataracts.

Synthesis of multi-cavity mesoporous carbon nanospheres through solvent-induced self-assembly: Anode material for sodium-ion batteries with long-term cycle stability

Mesoporous carbon nanospheres (MCSs) are extensively employed in energy storage applications due to their ordered pore size, large specific surface area (SSA), and abundant active sites, resulting in excellent electrochemical performance for sodium storage. However, challenges persist in achieving precise structural control and stable synthesis reactions for these MCSs. Additionally, employing MCSs with a larger SSA in sodium storage applications can lead to increased side reactions and potential structural instability. To address these issues, we propose a solvent-induced self-assembly method for obtaining high nitrogen-containing multi-cavity MCSs with reduced SSA. The morphology and SSA of the nanospheres can be precisely adjusted by regulating the reaction time. Introducing an amine-phenol bridging structure into the polymer system significantly bolsters the structural and morphological stability of the mesoporous materials. The performance of these novel nanospheres in sodium-ion batteries (SIBs) is remarkable, exhibiting excellent sodium storage capability and exceptional ultra-long cycle stability. At a rate of 0.1 A g-1, the nanospheres achieved a high reversible capacity of 252 mAh g-1, and even after 20,000 cycles at 5 A g-1, a specific capacity of 136 mAh g-1 was retained. In summary, our study presents a novel approach for synthesizing mesoporous carbon materials and offers valuable insights for sodium storage research, opening new possibilities for enhancing energy storage applications.

Structural analysis of polyglycerol fatty acid ester-coenzyme Q10 aggregates in solution

Polyglycerol fatty acid esters (PGFEs) are common food additives. PGFE-based formulations exhibit high structural stability, however, the stability mechanism of the micellar structures has not been yet elucidated. In this study, nanostructural analysis was performed using small-angle neutron and X-ray scattering (SANS and SAXS) measurements to reveal the mechanism of the structural stability of PGFE-coenzyme Q10 (CoQ10) mixtures as a CoQ10 formulation. Pure PGFE formed multilamellar vesicles, whereas PGFE-CoQ10 formed spherical micelles. Furthermore, when the amount of added water increased, the PGFE-CoQ10 micellar size and the amount of water in the micelles remained unchanged. A model-fitting analysis of the SANS results suggested that the CoQ10 molecules were introduced between the surfactants, forming a palisade-type structure. The high structural stability of the PGFE-CoQ10 micelles was attributed to two factors: proper spreading of the hydrophilic head chains and inhibition of the change of the amount of water inside the micelles by the PGFE heads and quinone ring of CoQ10. This indicates that PGFE-CoQ10 can function in water while maintaining the micellar structure formed in the storage solution. The findings of this study are important for the safety and nano-hazard aspects of PGFE-CoQ10 formulations.

A new high-valence cation pillar within the Li layer of compositionally optimized Ni-rich LiNi0.9Co0.1O2 with improved structural stability for Li-ion battery

Elevating the nickel (Ni) content within layered cathodes constitutes a straightforward and effective approach to enhance the energy density of lithium-ion batteries (LIBs). However, the phase transition from H2 to H3 introduces substantial alterations in lattice volume, leading to structural degradation and diminished electrochemical performance. This study employs density functional theory (DFT) calculations to determine that the formation energy for Nb5+ occupied at Li 3b sites is lower compared to that of Ni 3a and Co 3a sites, yet higher than that of Mn 3a sites. This suggests a preference for Nb5+ doping within the Li layer of Mn-free cathodes. Motivated by these DFT results, we show the viability of high-valence Nb5+ as a stable pillar in the compositionally optimized binary oxide LiNi0.9Co0.1O2. The inclusion of this Nb5+ pillar in the Li layer of Ni/Co-based oxide significantly enhances the reversibility of the H2-H3 redox couple and mitigates microcrack formation in polycrystalline cathodes. As a result, the Nb-doped Ni/Co-based cathode exhibits an extended cycling lifespan, elevated rate capability, and increased thermal stability compared to the undoped. This investigation achieves precise control over doping sites by optimizing the chemical composition of Ni-rich cathodes and provides novel insights into advancing their electrochemical performance for high-energy LIBs.

Effect of ferrous ions combined with zeolite on humification degree during food waste composting

The research aims to clarify role of ferrous sulfate (FeSO4) combined with zeolite (Z) on humification degree based on investigation of concentration and structural stability of humic acid (HA) during food waste composting. Four treatments were set up, namely CK (control), Fe (5 %), Z (5 %) and Fe + Z (2.5 %+2.5 %). Results demonstrated that concentration and polymerization degree of HA were 53.4 % and 97.3 % higher in composting amended with Fe + Z than in the control, respectively. Meanwhile, formation of aromatic functional groups and recalcitrant fluorescent components (HAC3) was significantly promoted, indicating that Fe + Z treatment enhanced HA structure stability. The bacterial networks became tighter, and the proportion of core bacteria in dominant modules increased at Fe + Z treatment. Additionally, key factors affecting HAC3 and product quality were identified by structural equation models, which verified potential mechanism of humification enhancement. Overall, this study provided theoretical support for improving humification degree and product quality.

Cu/Ti co-doping boosting P2-type Fe/Mn-based layered oxide cathodes for high-performance sodium storage

Environmentally friendly P2-type layered iron manganese oxides appear to be one of the most potential cathode materials for sodium-ion batteries (SIBs). However, their practical application is hindered by the unfavorable phase transitions, dissolution of transition metals, and poor air stability. One effective strategy by either single-cation doping or high-cost Li involved co-doping is used to alleviate the problems. Here, low-cost Cu/Ti co-doping is introduced to boost P2-Na0.7Cu0.2Fe0.2Mn0.5Ti0.1O2 as an air and electrochemical stable cathode material for SIBs. The resulting electrode delivers an initial capacity of 130 mAh g-1 at 0.1C within 2.0-4.2 V, a reversible discharge capacity of 61.0 mAh g-1 at a high rate of 5C and a capacity retention ratio exceeding 71.1% after 300 cycles. In particular, the co-doped crystal structure is well-maintained after 1 month of exposure to air, and even 3 days of soaking in water. Furthermore, the enhancement is elucidated by the effectively mitigated P2-Z and the completely suppressed P2-P'2 phase transitions, the decreased volume variation proved by in-situ X-ray diffraction (XRD), as well as the lowered transition-metal dissolution evidenced by inductively coupled plasma optical emission spectrometer (ICP-OES) and X-ray photoelectron spectroscopy (XPS). The low-lost Cu/Ti doping strategy could thus be effective for designing and preparing environmentally friendly and high-performance cathode materials for SIBs.

A thermodynamically stable O2-type cathode with reversible O2-P2 phase transition for advanced sodium-ion batteries

Low-cost sodium-ion batteries (SIBs) have shown very promise in the applications of renewable energy and low-speed electric vehicles. The development of a new O2-type cathode in SIBs is very challenging in that this compound is only stable as an intermediate product of P2-type oxides during redox reactions. Here, we report a thermodynamically stable O2-type cathode obtained by Na/Li ion exchange from P2-type oxide in a binary molten salt system. It is demonstrated that the as-prepared O2-type cathode exhibits a highly reversible O2-P2 phase transition during Na+ de-intercalation. The unusual O2-P2 transition has a low volume change of ∼11%, much lower than that of 23.2% for P2-O2 transformation in the P2-type cathode. The lowered lattice volume change of this O2-type cathode gives rise to superior structural stability upon cycling. Therefore, the O2-type cathode possesses a reversible capacity of about 100 mAh/g with a good capacity retention of 87.3% even after 300 cycles at 1C, indicating outstanding long-term cycling stability. These achievements will promote the development new class of cathode materials with high capacity and structural stability for advanced SIBs.

Current insights of factors interfering the stability of lytic polysaccharide monooxygenases

Cellulose and chitin are two of the most abundant biopolymers in nature, but they cannot be effectively utilized in industry due to their recalcitrance. This limitation was overcome by the advent of lytic polysaccharide monooxygenases (LPMOs), which promote the disruption of biopolymers through oxidative mechanism and provide a breakthrough in the action of hydrolytic enzymes. In the application of LPMOs to biomass degradation, the key to consistent and effective functioning lies in their stability. The efficient transformation of biomass resources using LPMOs depends on factors that interfere with their stability. This review discussed three aspects that affect LPMO stability: general external factors, structural factors, and factors in the enzyme-substrate reaction. It explains how these factors impact LPMO stability, discusses the resulting effects, and finally presents relevant measures and considerations, including potential resolutions. The review also provides suggestions for the application of LPMOs in polysaccharide degradation.

The structural stability, electronic properties regulation and feasibility of controllable preparation of a C0.5/(BN)0.5 heterojunction single-walled nanotube

Our work investigates the structural stability of a C 0.5 / ( BN ) 0.5 heterojunction single-walled nanotube by comparing the binding energy. The energy band structure, electronic density of states and regulation relation between band gap and indirect-direct properties and tube diameter and type are systematically studied. Based on existing experimental and theoretical results, dynamic simulated calculating of the stitching process is carried out to explore the feasibility of controllable preparation.

FRET-based analysis on the structural stability of polymeric micelles: Another key attribute beyond PEG coverage and particle size affecting the blood clearance

Various attributes of micelles, such as PEG density and particle size, are considered to be related to blood clearance. The structural stability of micelles is another key attribute that will affect the in vivo fate. This study employed fluorescence resonance energy transfer (FRET) analysis to guide the preparation of polymeric micelles with different structural stability. Micelles prepared using copolymers with longer hydrophobic blocks showed higher structural stability; emulsification was a better method than nanoprecipitation to prepare stable micelles. The fast chain exchange kinetics and the high-water content of micellar cores explained the low structural stability of those micelles. Moreover, this study highlighted the importance of structural stability that affected blood clearance in concert with PEG length and particle size. One-third of the small and stable micelles were detected in the blood 24 h after injection. While unstable micelles would be cleared from the circulation within 4 h. Notably, there would be a threshold of structural stability. Micelles with structural stability below this threshold were quickly cleared even if they possessed a longer PEG length and a smaller size. In contrast, higher structural stability allowed polymeric micelles to maintain higher integrity in vivo and enhance tumor accumulation and anti-tumor efficacy. In conclusion, this study systematically analyzed the importance of the structural stability of micelles on the in vivo fate.

Structural and Biophysical properties of therapeutically important proteins Rv1509 and Rv2231A of Mycobacterium tuberculosis

Through comparative analyses using BLASTp and BLASTn of the 25 target sequences, our research identified two unique post-transcriptional modifiers, Rv1509 and Rv2231A, which serve as distinctive and characteristic proteins of M.tb - the Signature Proteins. Here, we have characterized these two signature proteins associated with pathophysiology of M.tb which may prove to be therapeutically important targets. Dynamic Light Scattering and Analytical Gel Filtration Chromatography exhibited that Rv1509 exists as a monomer while Rv2231A as a dimer in solution. Secondary structures were determined using Circular Dichroism and further validated through Fourier Transform Infrared spectroscopy. Both the proteins are capable of withstanding a wide range of temperature and pH variations. Fluorescence spectroscopy based binding affinity experiments showed that Rv1509 binds to iron and may promote organism growth by chelating iron. In the case of Rv2231A, a high affinity for its substrate RNA was observed, which is facilitated in presence of Mg2+ suggesting it might have RNAse activity, supporting the prediction through in-silico studies. This is the first study on biophysical characterization of these two therapeutically important proteins, Rv1509 and Rv2231A, providing important insights into their structure -function correlations which are crucial for development of new drugs/ early diagnostics tools targeting these proteins.

First-principles investigation of stable lead-free halide perovskite materials CsSnClxBryI3-x-yfor solar cell applications

Perovskite solar cells based on hybrid organic-inorganic lead halide materials have attracted immense interest in recent years due to their enhanced power conversion efficiency. However, the toxic lead element and unstable property of the material limit their applications. With first-principles calculations based on density functional theory, we studied a series of ten lead-free perovskite materials made of cesium, tin, and halogen elements, chlorine (Cl), bromine (Br), and iodine (I). We found that the relative concentrations of the halogen atoms determine the crystal structures and the relative stability of the halide perovskites. Chlorine tends to increase the structural stability, while iodine plays the role of reducing the band gaps of the mixed halide perovskites. Considering the stability and the requirement of suitable band gaps, we identify that, among the ten lead-free halide perovskites, CsSnCl₂I, CsSnBr₂I, CsSnClBrI, CsSnClI₂, CsSnBrI₂, and CsSnI₃are the appropriate choices for solar cell applications.&#xD.

Granule formation mechanism, key influencing factors, and resource recycling in aerobic granular sludge (AGS) wastewater treatment: A review

The high-efficiency and additionally economic benefits generated from aerobic granular sludge (AGS) wastewater treatment have led to its increasing popularity among academics and industrial players. The AGS process can recycle high value-added biomaterials including extracellular polymeric substances (EPS), sodium alginate-like external polymer (ALE), polyhydroxyfatty acid (PHA), and phosphorus (P), etc., which can serve various fields including agriculture, construction, and chemical while removing pollutants from wastewaters. The effects of various key operation parameters on formation and structural stability of AGS are comprehensively summarized. The degradable metabolism of typical pollutants and corresponding microbial diversity and succession in the AGS wastewater treatment system are also discussed, especially with a focus on emerging contaminants removal. In addition, recent attempts for potentially effective production of high value-added biomaterials from AGS are proposed, particularly concerning improving the yield, quality, and application of these biomaterials. This review aims to provide a reference for in-depth research on the AGS process, suggesting a new alternative for wastewater treatment recycling.

Extreme thermal stability of the antiGFP nanobody - GFP complex

OBJECTIVE

The green fluorescent protein (GFP) and its derivatives are widely used in biomedical research. The manipulation of GFP-tagged proteins by GFP-specific binders, e.g. single-domain antibodies (nanobodies), is of increasing significance. It is therefore important to better understand the properties of antiGFP-GFP interaction in order to establish methodological applications. In this work the interaction of superfolder GFP (sfGFP) and its enhancer nanobody (aGFP_enh) was characterized further.

RESULTS

Previous calorimetric experiments demonstrated that the aGFP_enh nanobody binds strongly to sfGFP with a nanomolar affinity. Here we show that this interaction results in a substantial structural stabilization of aGFP_enh reflected in a significant increase of its melting temperature by almost 30 °C. The thermal stability of the sfGFP-aGFP_enh complex is close to 85 °C in the pH range 7.0-8.5. For therapeutic applications thermoresistance is often an essential factor. Our results suggest that methodologies based on GFP-aGFP interaction can be applied under a wide range of physicochemical conditions. The aGFP_enh nanobody seems to be suitable for manipulating sfGFP-labeled targets even in extreme thermophilic organisms.

Preparation of long-term cycling stable ni-rich concentration-gradient NCMA cathode materials for li-ion batteries

Nickel-rich (Ni > 90 %) cathodes are regarded as one of the most attractive because of their high energy density, despite their poor stability and cycle life. To improve their performance, in this study we synthesized a double concentration-gradient layered Li[Ni_0.90Co_0.04Mn_0.03Al_0.03]O₂ oxide (CG-NCMA) using a continuous co-precipitation Taylor-Couette cylindrical reactor (TCCR) with a Ni-rich-core, an Mn-rich surface, and Al on top. The concentration-gradient morphology was confirmed through cross-sectional EDX line scanning. The as-synthesized sample exhibited excellent electrochemical performance at high rates (5C/10C), as well as cyclability (91.5 % after 100 cycles and 70.3 % after 500 cycles at 1C), superior to that (83.4 % and 47.6 %) of its non-concentration-gradient counterpart (UC-NCMA). The Mn-rich surface and presence of Al helped the material stay structurally robust, even after 500 cycles, while also suppressing side reactions between the electrode and electrolyte, resulting in better overall electrochemical performance. These enhancements in performance were studied using TEM, SEM, in-situ-XRD, XPS, CV, EIS and post-mortem analyses. This synthetic method enables the highly scalable production of CG-NCMA samples with two concentration-gradient structures for practical applications in Li-ion batteries.

Highly compressible and hydrophobic nanofibrillated cellulose aerogels for cyclic oil/water separation

Nanofibrillated cellulose (NFC)-based aerogels are ideal oil-sorbent materials, but the poor structural stability and hydrophilicity restrain their practical applications in the fields of oil/water separation. In the present work, we report a facile strategy for constructing a hydrophobic nanofibrillated cellulose aerogel for cyclic oil/water separation. Briefly, an aerogel matrix of C-g-PEI with multiple cross-linked network structures was constructed via the combined use of oxidized-NFC (ONC), polyethyleneimine (PEI), and ethylene glycol diglycidyl ether (EGDE), followed by rapid in situ deposition of poly(methyl trichlorosilane) (PMTS) through a low-temperature gas-solid reaction. The resulting ONC-based aerogel (C-g-PEI-PMTS) exhibits the advantages of ultralight (53.80 mg/cm³), high porosity (95.73 %), hydrophobicity (contact angle of 130.0°) and remarkable elasticity (95.86 %). Meanwhile, the composite aerogel of C-g-PEI-PMTS is extremely suitable for oil sorption-desorption by a simple mechanical squeezing method. After 10 cycles of sorption-desorption, the sorption capacity of the aerogel towards various oils reached almost the same level as in the first cycle. The filtration separation efficiency for the trichloromethane-water mixtures remained at 99 % after 50 cycles, demonstrating encouraging reusability. In summary, an efficient strategy to prepare NFC-based aerogel with highly compressible and hydrophobic properties is developed, which expands the applications of NFC in the fields of oil/water separation.

Reaching the initial coulombic efficiency and structural stability limit of P2/O3 biphasic layered cathode for sodium-ion batteries

The P2/O3 biphasic layered oxide (Na_xMn_1-yM_yO₂, M: doping elements) is a cathode family with great promise for sodium-ion batteries (SIBs) because of their tunable electrochemical performance and low cost. However, the ultrahigh initial coulombic efficiency (ICE) and inferior cycling performance of P2/O3-Na_xMn_1-yM_yO₂ need to be improved for practical application. Herein, Ni/Cu co-doped P2/O3-Na_0.75Mn_1-yNi_y-zCu_zO₂ materials are well-designed. The ultrahigh ICE can be restrained by altering the ratio of P2/O3 via adjusting Ni content, and the structural stability can be improved by Cu doping via enlarging parameter c of O3 phase and suppressing irreversible P2-O2 phase transformation. The optimal P2/O3-Na_0.75Mn_0.6Ni_0.3Cu_0.1O₂ delivers a capacity of 142.4 with ICE of 107.8%, superior capacity retention in the temperature range of -40 ∼ 30 °C, and rate performance of 95.9 mAh g^-1 at 1.2 A g^-1. The overall storage mechanism of P2/O3-Na_0.75Mn_0.6Ni_0.3Cu_0.1O₂ is revealed by the combination of electrochemical profiles, in situ X-ray diffraction, and first-principles calculations. The Na-ion full battery based on P2/O3-Na_0.75Mn_0.6Ni_0.3Cu_0.1O₂ cathode can achieve a remarkable energy density of 306.9 Wh kg^-1 with a power density of 695.5 W kg^-1 at 200 mA g^-1. This work may shed light on the rational design of high-performance P2/O3 biphasic layered cathode for SIBs.

Cataract-causing variant Q70P damages structural stability of βB1-crystallin and increases its tendency to form insoluble aggregates

Congenital cataract is the primary cause of childhood blindness worldwide. As the predominant structural protein, βB1-crystallin plays an important role in maintaining lens transparency and cellular homeostasis. Numerous cataract-causing mutations of βB1-crystallin have been identified with unclear pathogenic mechanism. We previously identified the mutation Q70P (Q to P at residue position 70) of βB1-crystallin linked to congenital cataract in a Chinese family. In this work, we investigated the potential molecular mechanism of βB1-Q70P in the congenital cataract at the molecular, protein, and cellular levels. We purified recombinant βB1 wild-type (WT) and Q70P proteins and compared their structural characteristics and biophysical properties by spectroscopic experiments under physiological temperature and environmental stresses (ultraviolet irradiation, heat stress, oxidative stress). Notably, βB1-Q70P significantly changed the structures of βB1-crystallin and exhibited lower solubility at physiological temperature. Meanwhile, βB1-Q70P was prone to aggregation in eukaryotic and prokaryotic cells, and was more sensitive to environmental stresses, along with impaired cellular viability. Furthermore, the molecular dynamics simulation indicated that the mutation Q70P damaged secondary structures and hydrogen bond network of βB1-crystallin, which were essential for the first Greek-key motif. This study delineated the pathological mechanism of βB1-Q70P and provided novel insights into treatment and prevention strategies for cataract-associated βB1 mutations.

Computational insight into in silico analysis and molecular dynamics simulation of the dimer interface residues of ALS-linked hSOD1 forms in apo/holo states: a combined experimental and bioinformatic perspective

The aggregation of misfolded SOD1 proteins in neurodegenerative illnesses is a key pathological hallmark in amyotrophic lateral sclerosis (ALS). SOD1 is stabilized and enzymatically activated after binding to Cu/Zn and forming intramolecular disulfide. SOD1 aggregation/oligomerization is triggered by the dissociation of Cu and/or Zn ions. Therefore, we compared the possible effects of ALS-associated point mutations of the holo/apo forms of WT/I149T/V148G SOD1 variants located at the dimer interface to determine structural characterization using spectroscopic methods, computational approaches as well as molecular dynamics (MD) simulations. Predictive results of computational analysis of single-nucleotide polymorphisms (SNPs) suggested that mutant SOD1 has a deleterious effect on activity and structure destabilization. MD data analysis indicated that changes in flexibility, stability, hydrophobicity of the protein as well as increased intramolecular interactions of apo-SOD1 were more than holo-SOD1. Furthermore, a decrease in enzymatic activity in apo-SOD1 was observed compared to holo-SOD1. Comparative intrinsic and ANS fluorescence results of holo/apo-WT-hSOD1 and mutants indicated structural alterations in the local environment of tryptophan residue and hydrophobic patches, respectively. Experimental and MD data supported that substitution effect and metal deficiency of mutants (apo forms) in the dimer interface may promote the tendency to protein mis-folding and aggregation, consequently disrupting the dimer-monomer equilibrium and increased propensity to dissociation dimer into SOD-monomer ultimately leading to loss of stability and function. Overall, data analysis of apo/holo SOD1 forms on protein structure and function using computational and experimental studies will contribute to a better understanding of ALS pathogenicity.

Structural and functional characterization of colonization factors AIBI-CS6 and AIIBII-CS6 of enterotoxigenic Escherichia coli

Over time, the structure and function of the broadly dispersed colonization factor (CF) CS6 of enterotoxigenic Escherichia coli (ETEC) have become more significant. CS6 is composed of tightly-associated subunits, CssA and CssB which due to presence of natural point mutation gave rise to CS6 subtypes. In contrast to the other ETEC CFs, CS6 is an afimbrial, spherical-shaped oligomers of (CssA-CssB)_n complex where 'n' is concentration dependent. In this study, we have compared AIBI-CS6 and AIIBII-CS6 structurally and functionally. The M_w of CssAI was 18.5 kDa but M_w of CssAII was 15.1 kDa. Both CssBI and CssBII had M_w of 15.9 kDa. The substitution of Gly³⁹ with Ala³⁹ in CssAI leads to reduction in Mw from 18.5 to 15.1 kDa. Due to higher M_w of CssAI, the size of AIBI concentration-dependent oligomers should be higher. However, the M_w of AIIBII oligomers were higher and AIIBII also showed higher oligomeric forms compared to AIBI both in native PAGE and electron microscopy. The oligomers of both subtypes could withstand greater temperatures and denaturant concentrations. In terms of cellular response, the levels of inflammatory cytokines were significantly higher in case of AIBI-CS6 expressing ETEC as compared to AIIBII-CS6 expressing ETEC both in vitro and in vivo. When inflammatory cytokines were evaluated after infecting suckling mice with these ETEC strains, the results were consistent. In conclusion, even though there was subtle structural difference between AIBI-CS6 and AIIBII-CS6 due to natural point mutations but ETEC strains expressing these subtypes displayed great variability in pathogenicity.

Pillar strategy enhanced ion transport and structural stability toward ultra-stable KVPO4F cathode for practical potassium-ion batteries

KVPO₄F (KVPF) is a promising cathode material for potassium-ion batteries (PIBs) because of its high operating voltage, high energy density, and excellent thermal stability. Nevertheless, the low kinetics and large volume change have been the major hurdles causing irreversible structural damage, high inner resistance, and poor cycle stability. Herein, a pillar strategy of Cs⁺ doping in KVPO₄F is introduced to reduce the energy barrier for ion diffusion and volume change during potassiation/depotassiation, which significantly enhances the K⁺ diffusion coefficient and stabilizes the crystal structure of the material. Consequently, the K_0.95Cs_0.05VPO₄F (Cs-5-KVPF) cathode exhibits an excellent discharge capacity of 104.5 mAh g^-1 at 20 mA g^-1 and a capacity retention rate of 87.9% after 800 cycles at 500 mA g^-1. Importantly, Cs-5-KVPF//graphite full cells attain an energy density of 220 Wh kg^-1 (based on the cathode and anode weight) with a high operating voltage of 3.93 V and 79.1% capacity retention after 2000 cycles at 300 mA g^-1. The Cs-doped KVPO₄F cathode successfully innovates the ultra-durable and high-performance cathode materials for PIBs, demonstrating its considerable potential for practical applications.

Analysis of inhibition of guava (Psidium guajava l.) leaf polyphenol on the protein oxidative aggregation of frozen chicken meatballs based on structural changes

This study compared the effects of guava leaf polyphenol (GLP) on the aggregation and structural changes of myofibrillar proteins (MPs) from chicken meatballs, frozen for 6 months, with that of tea polyphenol (TP). The high antioxidation ability of 450 mg/L GLP was manifested by changes in 1, 1-diphenyl-2-picrylhydrazyl (DDPH), 2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, and the ferric reducing antioxidant power (FRAP) in vitro. Compared with the control, the carbonyl, disulfide bond content, particle size, zeta potential and turbidity of sample with GLP decreased by 25.9 %, 17.7 %, 18.2 %, 11.4 % and 11.7 %, respectively, while the solubility of the sample, after freezing it for 6 months, increased by 14.8 %. Meanwhile, in sustaining the structural stability of MPs, the GLP-treated group exhibited better microstructure (scanning electron microscopy, SEM), lower free amino and sulfhydryl loss, higher α-helix structure and fluorescence intensity than the control. Our results showed that GLP significantly inhibited MP aggregation, and was superior to TP in terms of its particle size, solubility, and turbidity, sulfhydryl content (P < 0.05). Overall, it was demonstrated that GLP has the potential to inhibit protein aggregation and enhance structural stability during frozen storage.

Substitution of carbonate by non-physiological synergistic anion modulates the stability and iron release kinetics of serum transferrin

Serum transferrin (sTf) is a bi-lobal protein. Each lobe of sTf binds one Fe³⁺ ion in the presence of a synergistic anion. Physiologically, carbonate is the main synergistic anion but other anions such as oxalate, malonate, glycolate, maleate, glycine, etc. can substitute for carbonate in vitro. The present work provides the possible pathways by which the substitution of carbonate with oxalate affects the structural, kinetic, thermodynamic, and functional properties of blood plasma sTf. Analysis of equilibrium experiments measuring iron release and structural unfolding of carbonate and oxalate bound diferric-sTf (Fe₂sTf) as a function of pH, urea concentration, and temperature reveal that the structural and iron-centers stability of Fe₂sTf increase by substitution of carbonate with oxalate. Analysis of isothermal titration calorimetry (ITC) scans showed that the affinity of Fe³⁺ with apo-sTf is enhanced by substituting carbonate with oxalate. Analysis of kinetic and thermodynamic parameters measured for the iron release from the carbonate and oxalate bound monoferric-N-lobe of sTf (Fe_NsTf) and Fe₂sTf at pH 7.4 and pH 5.6 reveals that the substitution of carbonate with oxalate inhibits/retards the iron release via increasing the enthalpic barriers.

Unveiling significance of Ca2+ ion for start-up of aerobic granular sludge reactor by distinguishing its effects on physicochemical property and bioactivity of sludge

Almost all of the aerobic granular sludge (AGS) reactors were fed on certain amounts of Ca²⁺ ion, but whether and why it was necessary for reactor start-up remain unknown. Herein, this study conducted a set of comparative experiments in three AGS reactors, which were operated in parallel with Ca²⁺ addition in R3, hydroxyapatite (HAP) addition in R1, and without any forms of Ca addition in R2. Results showed that R3 not only achieved the complete granulation of sludge, but exhibited superior performance of COD and nutrient removal. In contrast, R1 had a slightly quicker granulation rate than R3 (R1: 0.07 day^-1; R3: 0.06 day^-1), but the formed granules could not efficiently degrade pollutants. In R2, both sludge granulation and pollutants removal did not proceed normally. Further investigations found that the Ca²⁺ ion acted in three ways: (1) it increased inorganic composition of sludge to promote granulation; (2) the transformed HAP strengthened stability of granular structure; (3) it ensured bioactivity of granules by driving enrichment of functional microbes and synthesis of metabolism enzymes. Overall, this study systemically proved significance of Ca²⁺ ion for the start-up of AGS reactors and its influencing mechanisms on different properties of granules.

Boosting performance of Co-free Li-rich cathode material through regulating the anionic activity by means of the strong TaO bonding

Benefiting from the extra contribution of O redox, Co-free Li-rich layered oxides (LRNMO) can satisfy the requirement of high specific capacities. However, during the high-voltage charging process, lattice oxygen being oxidized to O^- or O₂ leads to a gradual transition of the structure from layered to spinel phase, capacity and voltage decline, hindering the practical application of LRNMO in the lithium-ion battery. Here, a surface modification strategy of Li_1.2Ni_0.32Mn_0.48O_2-δ doped with Ta⁵⁺ ions is proposed, in which the Ta⁵⁺ ions occupy the lithium sites of the lattice structure on the surface layer of LRNMO and form a Ta₂O₅ coating layer. The modified electrode exhibits excellent rate performance and cycling stability, with 94.9% and 85.5% capacity retention rate and voltage retention rate, respectively, after 200 cycles at 1C. Moreover, the initial coulomb efficiency and ionic conductivity of the modified electrode are also apparently enhanced. Simultaneously, the decreased Li/Ni mixing degree of the modified electrode reflects the improvement of the structural stability. Therefore, the modification strategy through strong metal-oxygen bonding to integrate the surface structure to regulate the oxygen activity provides a new direction for the design of high energy density Co-free Li-rich cathode materials.

Investigation of W6+-doped in high-nickel LiNi0.83Co0.11Mn0.06O2 cathode materials for high-performance lithium-ion batteries

WO₃ as tungsten dopant is introduced into lithium nickel cobalt manganese (LiNi_0.83Co_0.11Mn_0.06O₂, NCM) layered oxide powders to synthesize W⁶⁺-doped NCM cathode materials during the lithiation process of the hydroxide precursor. Introducing W⁶⁺ into the lattice can lead to the diversities of the crystal structure, surface morphology, and electrochemical performance. The crystal structure confirmed by X-ray diffraction indicates that the W⁶⁺-doped oxide powders present a typical R-3m layered structure with larger interplanar distance and cell volume. Also, scanning electron microscope images reveal that the primary particles shrink forming a tighter surface under the effect of W⁶⁺, while the specific changes gradually aggravate with increase in the content of W⁶⁺ added. The excellent electrochemical stability of W⁶⁺-doped samples is observed, as the stable host structure is reinforced by the strong W-O bond. The stable structure does not only inhibit the anisotropic volume change caused by repetitive H2 ⇔ H3 phase transitions, but also sustains the integrated structure to impede the formation of microcracks and the appearance of more side reactions. This research provides an effective route on investigating the potential association between electrochemical performance and structure change for W⁶⁺-doped strategy.

Temperature dependent autocleavage and applications of recombinant L-asparaginase from Thermococcus kodakarensis for acrylamide mitigation

This manuscript describes enhancement of soluble production, auto-cleavage analysis and assessment of acrylamide mitigation potential of Tk2246, a plant-type L-asparaginase from Thermococcus kodakarensis. The gene encoding Tk2246 was cloned and expressed in Escherichia coli. Recombinant Tk2246 was produced mainly in insoluble form. Various strategies were utilized to enhance the soluble production, which significantly increased the soluble yield. Interestingly, recombinant Tk2246 was produced even without addition of the inducer, though relatively in a lower amount. To our surprise, Tk2246 was produced in partially cleaved form when the inducer was not added in the culture. When applied for acrylamide mitigation, Tk2246 reduced the acrylamide formation more than 80% in French fries, chapati and yeast-leavened bread. In addition to acrylamide mitigation, Tk2246 exhibited antistaling activity without loss of sensory properties of the food. High activity, thermostability and efficient acrylamide reduction capability make Tk2246 a potential candidate for industrial applications.

Autoproteolysis of Procerain and Procerain B mediated by structural changes

Procerain (Pc) and Procerain B (PcB) are two latex proteases from Calotropis procera having potential applications in food and other industries. However, autolytic degradation of these proteases limits their potential use in industry. Nevertheless, basic mechanism underlying the autoproteolysis has not been detailed. In order to understand the same, we subjected the enzymes to various denaturing and activating conditions. The results showed that structural changes induced by different denaturing conditions trigger their autoproteolysis. We also observed differential response of Pc, PcB and other papain-like proteases towards autocatalysis in presence of reducing agent in-spite of sharing the same structural fold, including the number of disulfide bonds. The possible reason underlying this intriguing observation is also discussed. Further, present work establishes that structural changes in the proteases lead to autoproteolysis and the enzymes are stable unless they experience structural perturbation. These findings could thus be useful for their practical applications in industries.

Investigating effect of mutation on structure and function of G6PD enzyme: a comparative molecular dynamics simulation study

Several natural mutants of the human G6PD enzyme exist and have been reported. Because the enzymatic activities of many mutants are different from that of the wildtype, the genetic polymorphism of G6PD plays an important role in the synthesis of nucleic acids via ribulose-5-phosphate and formation of reduced NADP in response to oxidative stress. G6PD mutations leading to its deficiency result in the neonatal jaundice and acute hemolytic anemia in human. Herein, we demonstrate the molecular dynamics simulations of the wildtype G6PD and its three mutants to monitor the effect of mutations on dynamics and stability of the protein. These mutants are Chatham (A335T), Nashville (R393H), Alhambra (V394L), among which R393H and V394L lie closer to binding site of structural NADP⁺. MD analysis including RMSD, RMSF and protein secondary structure revealed that decrease in the stability of mutants is key factor for loss of their activity. The results demonstrated that mutations in the G6PD sequence resulted in altered structural stability and hence functional changes in enzymes. Also, the binding site, of structural NADP⁺, which is far away from the catalytic site plays an important role in protein stability and folding. Mutation at this site causes changes in structural stability and hence functional deviations in enzyme structure reflecting the importance of structural NADP⁺ binding site. The calculation of binding free energy by post processing end state method of Molecular Mechanics Poisson Boltzmann SurfaceArea (MM-PBSA) has inferred that ligand binding in wildtype is favorable as compared to mutants which represent destabilised protein structure due to mutation that in turn may hinder the normal physiological function. Exploring individual components of free energy revealed that the van der Waals energy component representing non-polar/hydrophobic energy contribution act as a dominant factor in case of ligand binding. Our study also provides an insight in identifying the key inhibitory site in G6PD and its mutants which can be exploited to use them as a target for developing new inhibitors in rational drug design.

Graphene-based SiC Van der Waals heterostructures: nonequilibrium molecular dynamics simulation study

The structural properties and thermal conductivity of graphene-based SiC heterostructures are investigated using the reverse nonequilibrium molecular dynamics. The C/SiC/C heterostructure has the greatest value of cohesive energy due to the effect of vdW interactions between layers. The surfaces of heterostructures begin to ripple as a direct consequence of the plane fluctuations observed around T = 400 K. The thermal conductivity at room temperature is determined. The length and the armchair and zigzag orientations increase the magnitude of κ which decreases with increasing temperature. This change is attributed to the phonon Umklapp scattering and phonon cross-plane couplings. The impact of point vacancy, bi-vacancy and edge vacancy in a concentration range up to 2% is also discussed. The localization of low-frequency phonons around the vacancy induces a decaying characteristic of thermal conductivity. The effect depends on the type of vacancy and is more pronounced in heterostructures with point vacancy. The present results make pristine and defective heterostructures promising materials for various thermoelectric applications with tunable functionalities.

A descriptor for the structural stability of organic-inorganic hybrid perovskites based on binding mechanism in electronic structure

The poor stability of organic-inorganic hybrid perovskites hinders its commercial application, which motivates a need for greater theoretical insight into its binding mechanism. To date, the binding mode of organic cation and anion inside organic-inorganic hybrid perovskites is still unclear and even contradictory. Therefore, in this work based on density functional theory (DFT), the binding mechanism between organic cation and anion was systematically investigated through electronic structure analysis including an examination of the electronic localization function (ELF), electron density difference (EDD), reduced density gradient (RDG), and energy decomposition analysis (EDA). The binding strength is mainly determined by Coulomb effect and orbital polarization. Based on the above analysis, a novel 2D linear regression descriptor that E_b =  - 9.75Q²/R₀ + 0.00053 V∙E_HL - 6.11 with coefficient of determination R² = 0.88 was proposed to evaluate the binding strength (the units for Q, R₀, V, and E_HL are |e|, Å, bohr³, and eV, respectively), revealing that larger Coulomb effect (Q²/R₀), smaller volume of perovskite (V), and narrower energy difference (E_HL) between the lowest unoccupied molecular orbital (LUMO) of organic cation and the highest occupied molecular orbital (HOMO) of anion correspond to the stronger binding strength, which guides the design of highly stable organic-inorganic hybrid perovskites.

Congenital cataract-causing mutation βB1-L116P is prone to amyloid fibrils aggregation and protease degradation with low structural stability

Congenital cataract, a common disease with lens opacification, causes blindness in the newborn worldwide and is mainly caused by abnormal aggregation of crystallin. As the main structural protein in the mammalian lens, βB1-crystallin has an important role in the maintenance of lens transparency. Recently, the L116P mutation in βB1-CRY was found in a Chinese family with congenital nuclear cataracts, while its underlying pathogenic mechanism remains unclear. In the current study, the βB1 wild-type protein was purified, and the mutated form, βB1-L116P, was examined for examining the effect on structural stability and susceptibility against environmental stresses. Our results reveal low solubility and structural stability of βB1-L116P at physiological temperature, which markedly impaired the protein structure and the oligomerization of βB1-crystallin. Under guanidine hydrochloride-induced denaturing conditions, βB1-L116P mutation perturbed the protein unfolding process, making it prone to amyloid fibrils aggregation. More importantly, the L116P mutation increased susceptibility of βB1-crystallin against UV radiation. βB1-L116P overexpression led to the formation of more serious intracellular aggresomes under UV radiation or oxidative stress. Furthermore, the βB1-L116P mutation increased the sensitivity to the proteolysis process. These results indicate that the low structural stability, susceptibility to amyloid fibrils aggregation, and protease degradation of βB1-L116P may contribute to cataract development and associated symptoms.

Metallization-Prompted Robust Porphyrin-Based Hydrogen-Bonded Organic Frameworks for Photocatalytic CO2 Reduction

Under topological guidance, the self-assembly process based on a tetratopic porphyrin synthon results in a hydrogen-bonded organic framework (HOF) with the predicted square layers topology (sql) but unsatisfied stability. Strikingly, simply introducing a transition metal in the porphyrin center does not change the network topology but drastically causes noticeable change on noncovalent interaction, orbital overlap, and molecular geometry, therefore ultimately giving rise to a series of metalloporphyrinic HOFs with high surface area, and excellent stability (intact after being soaked in boiling water, concentrated HCl, and heated to 270 °C). On integrating both photosensitizers and catalytic sites into robust backbones, this series of HOFs can effectively catalyze the photoreduction of CO₂ to CO, and their catalytic performances greatly depend on the chelated metal species in the porphyrin centers. This work enriches the library of stable functional HOFs and expands their applications in photocatalytic CO₂ reduction.

Deep blue autofluorescence reveals the instability of human transthyretin

Wild-type human transthyretin (TTR) is a tetrameric protein that transports thyroxine and retinol in the blood and brain. However, a number of mutations or aging leads to destabilization of the quaternary structure of TTR, which results in dissociation of TTR tetramers to monomers, followed by oligomerization and subsequent amyloid formation. TTR amyloid is a pathogenic factor underlying several diseases. It has recently been documented that destabilization of the structure of TTR is driven by Ca²⁺. The present work shows that the in vitro redox conditions contribute to the destabilization and formation of the highly unstable substoichiometric population(s) of TTR molecules. Importantly, destabilized TTR forms acquire the ability to emit fluorescence in the blue range of the light spectrum. Dithiothreitol (DTT), in the presence of Ca²⁺, enhances the formation of complex autofluorophore which displays maxima at 417 nm and 438 nm in the emission spectrum of TTR.

Climate modelling and structural stability

Climate modelling plays a crucial role for understanding and addressing the climate challenge, in terms of both mitigation and adaptation. It is therefore of central importance to understand to what extent climate models are adequate for relevant purposes, such as providing certain kinds of climate change projections in view of decision-making. In this perspective, the issue of the stability of climate models under small relevant perturbations in their structure (or small relevant 'structural model errors' with respect to the target system) seems particularly important. Within this framework, a debate has emerged in the philosophy of science literature about the relevance for climate modelling of the mathematical notion of structural stability. This paper adresses several important foundational and epistemological questions that arise in this context, in particular about the the role of abstract mathematical considerations of a qualitative nature (in some precise, topological sense) for concrete modelling projects with mainly quantitative purposes.

The catalytic performance of Cu46Zr47-xAl7Yx amorphous ribbons in the degradation of AO II dye wastewater

Metallic glasses (MGs) with unique disordered atomic stacking structures exhibit excellent catalytic performance in wastewater treatment. The catalytic degradation of Orange II (AO II) aqueous solutions by four CuZr-based MG ribbons under such processing parameters as pH values, the dosage of ribbons, and temperature was investigated in this paper. The catalytic performance of the MG ribbons was characterized by using the degradation efficiency of the dye wastewater. The phase constituent, surface morphology, and chemical valence state of elements on the surface of MG ribbons before and after use were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that the Cu₄₆Zr₄₂Al₇Y₅ MG ribbon has the best catalytic performance among the Cu₄₆Zr_47-xAl₇Y_x (x = 0, 1, 3, 5) MGs in the degradation process, and the dye in the wastewater can almost be completely decolorized within 60 min under the conditions of pH = 2, the dosage of ribbons being 1.8 g/L and water bath temperature of 313 K, with the degradation efficiency and chemical oxygen demand removal being 96.05% and 51.73%, respectively. Furthermore, the Cu₄₆Zr₄₂Al₇Y₅ MG ribbon still shows superior structural stability and degradation performance after repeated use, and the corrosion pits on the MG surface promote the physicochemical reaction between the wastewater and the ribbons.

Mapping human calreticulin regions important for structural stability

Calreticulin (CALR) is a highly conserved multifunctional chaperone protein primarily present in the endoplasmic reticulum, where it regulates Ca²⁺ homeostasis. Recently, CALR has gained special interest for its diverse functions outside the endoplasmic reticulum, including the cell surface and extracellular space. Although high-resolution structures of CALR exist, it has not yet been established how different regions and individual amino acid residues contribute to structural stability of the protein. In the present study, we have identified key residues determining the structural stability of CALR. We used a Saccharomyces cerevisiae expression system to express and purify 50 human CALR mutants, which were analysed for several parameters including secretion titer, melting temperature (T_m), stability and oligomeric state. Our results revealed the importance of a previously identified small patch of conserved surface residues, amino acids 166-187 ("cluster 2") for structural stability of the human CALR protein. Two residues, Tyr172 and Asp187, were critical for maintaining the native structure of the protein. Mutant D187A revealed a severe drop in secretion titer, it was thermally unstable, prone to degradation, and oligomer formation. Tyr172 was critical for thermal stability of CALR and interacted with the third free Cys163 residue. This illustrates an unusual thermal stability of CALR dominated by Asp187, Tyr172 and Cys163, which may interact as part of a conserved structural unit. Besides structural clusters, we found a correlation of some measured parameter values in groups of CALR mutants that cause myeloproliferative neoplasms (MPN) and in mutants that may be associated with sudden unexpected death (SUD).

Impact of fungal pellets dosage on long-term stability of aerobic granular sludge

The effects of fungal pellets (FPs) dosage on both structural and functional stability of aerobic granular sludge (AGS) were investigated during 200-day operation. Results showed that the AGS induced by low (a dry mass ratio of FPs to seed sludge, 30%) and high FPs dosage (60%) exhibited good morphology integrity during the entire phase of operation, while the filamentous overgrowth and AGS breakup were observed in the control reactor (0% FPs). Moreover, the granules developed at high FPs dosage demonstrated excellent nutrients removal (COD: 93%; NH4⁺-N: 100%; TN: 77%) and stable bioactivity with a maximum specific oxygen uptake rate (SOUR) of 52.6 ± 2.6 mg O₂/(gVSS·h), a value being 12.2% and 26.7% higher than that of 30% and 0% dosage. The microbial community analysis revealed 60% FPs dosage enriched various functional bacteria involved in nutrients removal. This study suggests a sustainable strategy for improving structural and functional stability of AGS.

Comparison of functionality and structural stability of bacteriorhodopsin reconstituted in partially fluorinated dimyristoylphosphatidylcholine liposomes with different perfluoroalkyl chain lengths

Amphiphilic molecules with one or more perfluoroalkyl groups (Rf, C_nF_2n+1), which show peculiar interfacial properties, are attracting much attention in membrane protein science. We recently have developed a partially fluorinated dimyristoylphosphatidylcholine (DMPC) with a perfluorobutyl group in the hydrophobic chain terminal (F4-DMPC) and demonstrated that F4-DMPC is a promising material for incorporating membrane proteins. Moreover, we have found out that membrane properties of a series of partially fluorinated DMPCs with different Rf chain lengths (Fn-DMPCs) vary in a significant Rf chain length-dependent manner. In the present study, structural and functional properties of a membrane protein bacteriorhodopsin (bR) in the Fn-DMPC (n = 4, 6, and 8) membranes (bR/Fn-DMPC) are investigated using several physicochemical techniques. Regardless of the Rf chain lengths, bR/Fn-DMPCs retain native-like structural and functional properties at 30 °C, unlike bR molecules in DMPC vesicles. In particular, bR/F6-DMPC, which is in the fluid phase at 30 °C, shows flash-induced transient absorption changes very similar to the native purple membrane (PM) and very high thermal stability of bR trimers comparable to the PM. Structural and functional properties of bR/Fn-DMPCs are discussed compared to the PM and bR/DMPC.

Mechanical properties of ester- and ether-DPhPC bilayers: A molecular dynamics study

In addition to its biological importance, DPhPC lipid bilayers are widely used in droplet bilayers, study of integral membrane proteins, drug delivery systems as well as patch-clamp electrophysiology of ion channels, yet their mechanical properties are not fully measured. Herein, we examined the effect of the ether linkage on the mechanical properties of ester- and ether-DPhPC lipid bilayers using all-atom molecular dynamics simulation. The values of area per lipid, thickness, intrinsic lateral pressure profile, order parameter, and elasticity moduli were estimated using various computational frameworks and were compared with available experimental values. Overall, a good agreement was observed between the two. The global properties of the two lipid bilayers are vastly different, with ether bilayer being stiffer, less ordered, and thicker than ester bilayer. Moreover, ether linkage decreased the area per lipid in the ether lipid bilayer. Our computational framework and output demonstrate how ether modification changes the mechano-chemical properties of DPhPC bilayers.

Experiments and simulation on ZIKV NS2B-NS3 protease reveal its complex folding

Zika virus has been identified in various body fluids such as semen, urine, saliva, cerebrospinal fluid, and vaginal secretion of an infected individual. The pH of these fluids varies from mildly acidic to mildly alkaline. So it is imperative to understand the impact of these conditions on viral protein functioning. We investigated the NS2B-NS3 protease stability and its activity in different denaturing environments. Finding indicates that NS2B-NS3 protease maintains stability at pH 4.8-8.7. Thus it suggests that the complex remains functionally active to hydrolyze the polyprotein within a diverse environmental condition such as variable pH. Despite a stable structure at a broad pH range, a change in environmental conditions dramatically influence its protease activity. Moreover, it is susceptible to structural transformation leading to increased β-strand or helix content in the presence of alcohol. This study may help further to understand the folding-function relationship of the general flaviviral protease complex.

Spontaneous Formation of Highly Stable Nanoparticle Supercrystals Driven by a Covalent Bonding Interaction

Nanoparticle supercrystals (NPSCs) are of great interest as materials with emergent properties. Different types of intermolecular forces, such as van der Waals interaction and hydrogen bonding, are present in the NPSCs fabricated to date. However, the limited structural stability of such NPSCs that results from the weakness of these intermolecular forces is a challenge. Here, we report a spontaneous formation of NPSCs driven by covalent bonding interactions, a type of intramolecular force much stronger than the above-mentioned intermolecular forces. A model solution-phase anhydride reaction is used to form covalent bonds between molecules grafted on the surface of gold nanoparticles, resulting in three-dimensional NPSCs. The NPSCs are very stable in different solvents, in dried conditions, and at temperatures as high as 160 °C. In addition to this, the large library of covalent-bond-forming reactions available and the low cost of reactants make the covalent bonding approach highly versatile and economical.

Cataract-causing mutations L45P and Y46D promote γC-crystallin aggregation by disturbing hydrogen bonds network in the second Greek key motif

Congenital cataracts caused by genetic disorders are the primary cause of child blindness across the globe. In this work, we investigated the underlying molecular mechanism of two mutations, L45P and Y46D of γC-crystallin in two Chinese families causing nuclear congenital cataracts. Spectroscopic experiments were performed to determine structural differences between the wild-type (WT) and the L45P or Y46D mutant of γC-crystallin, and the structural stabilities of the WT and mutant proteins were measured under environmental stress (ultraviolet irradiation, pH disorders, oxidative stress, or chemical denaturation). The L45P and Y46D mutants had lower protein solubility and more hydrophobic residues exposed, making them prone to aggregation under environmental stress. The dynamic molecular simulation revealed that the L45P and Y46D mutations destabilized γC-crystallin by altering the hydrogen bonds network around the Trp residues in the second Greek key motif. In summary, L45P and Y46D mutants of γC-crystallin caused more hydrophobic residues to be solvent-exposed, lowered the solubility of γC-crystallin, and increased aggregation propensity under environmental stress. These might be the pathogenesis of γC-crystallin L45P and Y46D mutants related to congenital cataract.

Structural stability of SARS-CoV-2 3CLpro and identification of quercetin as an inhibitor by experimental screening

The global health emergency generated by coronavirus disease 2019 (COVID-19) has prompted the search for preventive and therapeutic treatments for its pathogen, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There are many potential targets for drug discovery and development to tackle this disease. One of these targets is the main protease, Mpro or 3CLpro, which is highly conserved among coronaviruses. 3CLpro is an essential player in the viral replication cycle, processing the large viral polyproteins and rendering the individual proteins functional. We report a biophysical characterization of the structural stability and the catalytic activity of 3CLpro from SARS-CoV-2, from which a suitable experimental in vitro molecular screening procedure has been designed. By screening of a small chemical library consisting of about 150 compounds, the natural product quercetin was identified as reasonably potent inhibitor of SARS-CoV-2 3CLpro (Ki ~ 7 μM). Quercetin could be shown to interact with 3CLpro using biophysical techniques and bind to the active site in molecular simulations. Quercetin, with well-known pharmacokinetic and ADMET properties, can be considered as a good candidate for further optimization and development, or repositioned for COVID-19 therapeutic treatment.

Continuous electrocoagulation degradation of oily wastewater with Fe78Si9B13 amorphous ribbons

The oily wastewater was treated by electrocoagulation with Fe₇₈Si₉B₁₃ amorphous ribbons as anode and graphite plates as cathode under such processing parameters as different pH values and current density, respectively. The degradation effect on the oily wastewater was characterized by chemical demand oxygen (COD), while the ribbons before and after using were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicate that under the conditions of pH = 3 and current density being 3.125 A/cm², the optimal COD removal efficiency was obtained to be 73.22%. Compared with the ordinary crystalline iron plate, the COD removal efficiency of resultant wastewater degraded by the amorphous ribbons is more than doubled. Simultaneously, the Fe₇₈Si₉B₁₃ amorphous ribbons exhibit good structural stability even after four cycles of using.

Destabilisation of the structure of transthyretin is driven by Ca2

Tetrameric transthyretin (TTR) transports thyroid hormones and retinol in plasma and cerebrospinal fluid and performs protective functions under stress conditions. Ageing and mutations result in TTR destabilisation and the formation of the amyloid deposits that dysregulate Ca²⁺ homeostasis. Our aim was to determine whether Ca²⁺ affects the structural stability of TTR. We show, using multiple techniques, that Ca²⁺ does not induce prevalent TTR dissociation and/or oligomerisation. However, in the presence of Ca²⁺, TTR exhibits altered conformational flexibility and different interactions with the solvent molecules. These structural changes lead to the formation of the sub-populations of non-native TTR conformers and to the destabilisation of the structure of TTR. Moreover, the sub-population of TTR molecules undergoes fragmentation that is augmented by Ca²⁺. We postulate that Ca²⁺ constitutes the structural and functional switch between the native and non-native forms of TTR, and therefore tip the balance towards age-dependent pathological calcification.

Stable lead-free perovskite solar cells: A first-principles investigation

A suitable substitution of the lead element in lead-based halide perovskites is a feasible approach to explore lead-free perovskite material with excellent stability, tunable band gap, high optical absorption, and better photovoltaic performance. In this study, the toxic lead is replaced by mixing Ba/Si and Ba/Sn to develop environmentally friendly perovskite materials with excellent properties. MABa_0.125Sn_0.875I₃ has shown evidently improved properties in terms of structural stability and suitable band gap, which indicates that MABa_0.125Sn_0.875I₃ can become the most potential material for applications in single-junction solar cells. Moreover, MABa_0.50Sn_0.50I₃ and MABa_0.25Sn_0.75I₃ can be promising materials for the top cell in the tandem architecture due to their proper band gaps (1.70-1.80 eV). Moreover, the optical absorption coefficients of the proposed lead-free perovskites are stronger than that of MAPbI₃ in the range of 500-800 nm. Our work can provide new insights into exploring lead-free perovskite solar cells with excellent stability and suitable band gap.