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In this study, single jersey knitted fabrics were produced from 100 % Ne 12/1 cotton, 100 % Ne 30/1 cotton, Ne 12/1 70% cotton + 30% hemp, Ne 30/1 50% modal + 50 % cotton, Ne 30/1 100 % viscose, and Ne 30/1 50 % viscose + 50 % cotton. The raw materials were bleached and singed, after which reactive pretreatment paste recipes were padded onto the fabrics, and then colored with digital printing. Fastness analyses and spectrophotometric color measurements were applied to the samples. When the results were determined, it was obviously seen that the washing, ironing, and rubbing fastness are of very high degrees because reactive dyestuffs make covalent bonds with the fibers. Thus, the increase in the amount of thickener also increased the bonding and provided better adhesion of the color. [ABSTRACT FROM AUTHOR]

The Mg 17 Al 12 -phase, which is common and important in Mg-Al alloy, has long been regarded as a brittle phase in experiments but theoretical calculations report controversial results. To unravel why theoretical calculations report controversial results and determine whether Mg 17 Al 12 is brittle or ductile, density functional theory calculations on atomic level are performed to investigate mechanic properties of Mg 17 Al 12 without containing alloying elements and without taking the size effect. The results showed that the parameter k -point played critical role in the DFT-based elastic calculations. The convergent G/B ratio of Mg 17 Al 12 was about 0.52, suggesting that the Mg 17 Al 12 -phase was theoretically ductile although its ductility was poor. The chemical bonding in Mg 17 Al 12 was the mixture of metallic Mg-Mg bond and covalent Al-Al bond. The advantage of metallic bonding over covalent bonding provided a possible explanation for the ductility of Mg 17 Al 12. Possible reasons for the brittleness of Mg 17 Al 12 in experiments are also discussed. [ABSTRACT FROM AUTHOR]

• 8-AN, 8-MQ, and 8-QSA chimisorbed on Mg(0001) surface via covalent bonds formation. • Upon the formation of coordination complexes between 8-AN and Mg2+, energy gap underwent change about ∆ E = 5.7 eV. • 8-AN, 8-MQ, and 8-QSA in their parallel configurations are found to interact strongly with the Mg atoms. • Electron donor effect of 8-AN compound strongly increases its coordination to Mg(0001) surface. • Interaction energies of all geometries follow the electrochemical performance trends. Heterocyclic compounds are the promising biological compounds as nature-friendly for the corrosion protection of metallic surface. In this work, three heterocyclic compounds such as 1-azanaphthalene-8-ol (8-AN), 2-methylquinoline-8-ol (8-MQ), and 8-quinolinol-5-sulfonic acid (8-QSA) were used as green compounds, and their anti-corrosion performance for AZ31 Mg in saline water was discussed on the basis of impedance interpretation and surface analysis. Findings found that the electrochemical performance was improved in the order of 8-AN > 8-MQ > 8-QSA, demonstrating the electron donor effect of N-heterocycles to form coordination complexes on the magnesium surface. From the electrochemical performance, the protective layer constructed at the optimal concentration reinforces the barrier against aggressive environments, with potential inhibition efficiency of 87.4%, 99.0%, and 99.9% for 8-QSA, 8-MQ, and 8-AN, respectively. Quantum chemical parameters and electron density distribution for free organic species in the absence and presence of Mg2+ cation were evaluated using density functional theory (DFT). Upon the formation of coordination complexes between organic compound and Mg2+, energy gap underwent change about ∆ E = 5.7 eV in the 8-AN/Mg2+ system. Furthermore, the adsorption of heterocyclic compounds on Mg surface reveals the formation of strong covalent bonds with Mg atoms, which further confirmed by the electron density difference and projected density of states analyses. Based on theoretical calculations, three inhibitors can adsorb on the metal surface in both parallel and perpendicular orientations via C, O and N atoms. In the parallel configuration, the C-Mg, N-Mg and O-Mg bond distances are between 2.11 and 2.25 Å, whereas the distances in the case of perpendicular adsorption are between 2.20 and 2.40 Å (covalent bonds via O and N atoms). The results indicated that parallel configurations are energetically more stable, in which the adsorption energies are -4.48 eV (8-AN), -4.28 eV (8-MQ) and -3.82 eV (8-QSA) compared to that of perpendicular adsorption (-3.65, -3.40, and -2.63 eV). As a result, experimental and theoretical studies were in well agreement and confirm that the nitrogen and oxygen atoms will be the main adsorption sites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Yttria: metal oxide useful in technological applications. • 3-Aminopropyltriethoxy silane (APTES) is a suitable molecular system used as substrate for binding monoclonal antibodies to the surface of yttria nanoparticles. • Use of MD and DFT calculations to explain the interactions between yttria and APTES. • Chemisorption and physisorption of APTES on yttria surface. • Dative bond between nitrogen and yttrium atoms. In this paper, the development of Dreiding force field parameters to describe the structural features of yttria, has been done through a test and trial procedure. The parameters are used to study the interactions occurring between yttria's surface with 3-aminopropyltriethoxy silane (APTES) molecular system, which has been used as a substrate to bind a monoclonal antibody (anti-CYFRA-21-1) to an adequately prepared surface of yttria nanoparticles. The work reveals that, on an eventual hydroxyl free metal-oxide surfaces the APTES molecules would adsorb on it with two layers. The first is a chemisorbed layer that covers the entire surface (surface-density of 2.10 × 10−6 mol/m 2) with a direct partially covalent dative bond between the nitrogen of the amine group of APTES and the yttrium atoms on the surface. The second is a physisorbed layer over the first, with a half the surface-density (c.a. 1.05 × 10−6 mol/m 2), where the APTES molecules amine groups are pointing outwards with respect to the surface. This makes possible the direct covalent bonding between the amine groups, of the outer adsorbed layer of APTES molecules, with the carboxylic group of the monoclonal anti-CYFRA-21-1 antibody. Quantum mechanical calculations confirmed the outcome of the force field study. [ABSTRACT FROM AUTHOR]

Identification and quantification of epigoitrin (EP) in some herbs and traditional Chinese medicine (TCM) preparations are critical to pharmacokinetic study and pharmaceutical quality control due to its distinct antiviral activity. So, developing highly sensitive and selective method for detection of EP is essential for clinical treatment and drug development. In this study, a novel molecularly imprinted electrochemical sensor for detection of EP was firstly constructed. With acrylamide imprinting systems, surface imprinting on the polyaniline functionalized graphene oxide was employed to prepare molecularly imprinted polymer by electropolymerization, which follow-up constructed afford specific binding cavities, endowing the exclusive recognition ability. Furthermore, the polyacrylamide chain is anchored to the polyaniline chain by covalent bonds, which is beneficial for raising electrochemistry signal. Under the optimized condition, the sensor demonstrates a linear wide range of 4.6 × 10−7 mol l−1 ∼ 4.6 × 10−5 mol l−1 with a correlation coefficient of 0.9953 and a low LOD of 8.21 × 10−8 mol l−1 (S/N = 3). Additionally, the sensor showed good stability, repeatability (RSD 1.52%) and selectivity. The method was applied to analyze EP in the extraction from Isatidis Radix with a recovery higher than 97.8% and RSD less than 1.81%. This work provided a novel strategy for on-site, realtime and rapid detection of indicator components from TCM. [ABSTRACT FROM AUTHOR]

The research aimed to evaluate the mechanical behaviour, hybridisation and osteoblast activities of novel baghdadite/PCL-graphene nanocomposite scaffold. The mechanical behaviour was examined via measuring the compressive strength and Young's module, the hybridisation was evaluated by Fourier transform infrared spectroscopy, Raman spectroscopy, and Brunauer Emmet Teller, and the osteoblast activities were assessed via MG-63 osteoblast cells. The results rendered PCL as a significant factor to enhance the mechanical strength of ceramic scaffolds. Due to the existence of σ and π covalent bonds in its structure, hydrophilicity and biocompatibility, graphene could be applied in scaffolds' chemical compound to greatly enhance their mechanical and biological behaviours. This scaffold indicated compressive strength and Young's module higher than 2 MPa and 0.05 GPa. Regarding cell behaviours, MG-63 osteoblast cells spread and attached well on the scaffolds confirming the viability, cytotoxicity, excellent cell attachment and proliferation. The results indicated that this scaffold possesses outstanding potential as a temporary substrate for bone tissue engineering. [ABSTRACT FROM AUTHOR]

In this study, in order to obtain selenium complex with high antioxidant activity and low release rate, selenium nanoparticles (SeNPs) were decorated by chemical reduction with Cyperus esculentus polysaccharides (CEP) as stabilizers (CEP-SeNPs). The characterization, construction mechanism, stability, and effects on properties in vitro digestion of CEP-SeNPs were investigated. CEP-SeNPs were orange-red in color and uniformly distributed in a spherical shape with an average diameter of 138.33 ± 0.57 nm, exhibiting good stability which could be stored at 4 °C. The selenium element in CEP-SeNPs was selenium in a zero-valent amorphous state. The O-H and C=O bonds in CEP were bound to selenium by an inductive effect to construct CEP-SeNPs for infrared analysis, and no new covalent bonds were formed in this process. CEP as stabilizer on selenium nanoparticles were physical combination. At the same time, the synergistic effects at antioxidant activity of polysaccharides and selenium was found which made CEP-SeNPs had a higher antioxidant activity than CEP. Above all, CEP-SeNPs showed better pH and enzyme stability in simulated digestion. The selenium release rate of CEP-SeNPs were only 18.52 % ± 0.17 % after intestinal digestion. The antioxidant activity of CEP-SeNPs were higher than that of CEP in the simulated digestion. It provides a theoretical basis for the development and utilization of rich selenium products. [Display omitted] • Synergistic effects at antioxidant activity of CEP and SeNPs was found. • With the combination of CEP, SeNPs had better pH and enzyme stability. • CEP-SeNPs showed lower selenium release rate in the simulated digestion. • CEP-SeNPs showed higher antioxidant activity than CEP in vitro digestion. [ABSTRACT FROM AUTHOR]

A mixed drug self-delivery system (DSDS) with high drug content (>50%) was developed to regulate pH-triggered drug release, based on two doxorubicin (DOX)-DOX dimmers: D-DOX ADH and D-DOX car conjugated with acid-labile dynamic covalent bonds (hydrazone and carbamate, respectively) and stabilized with PEGylated D-DOX ADH (D-DOX ADH -PEG). Owing to the different stability of the dynamic covalent bonds in the two dimers and the noncovalent interaction between them, pH-triggered drug release could be easily regulated by adjusting the feeding ratios of the two DOX-DOX dimers in the mixed DSDS. Similar in vitro cellular toxicity was achieved with the mixed DSDS nanoparticles prepared with different feeding ratios. The mixed DSDS nanoparticles had a similar DOX content and diameter but different drug releasing rates. The MTT assays revealed that a high anti-tumor efficacy could be achieved with the slow-release mixed DSDS nanoparticles. [Display omitted] • Mixed DSDS with high drug content was designed using two D-DOX dimers. • pH-Triggered release could be easily regulated by adjusting dimer feeding ratios. • Slow-release mixed DSDS nanoparticles showed high anti-tumor efficacy. [ABSTRACT FROM AUTHOR]

Thimerosal has been widely used as a preservative in drug and vaccine products for decades. Due to the strong propensity to modify thiols in proteins, conformational changes could occur due to covalent bond formation between ethylmercury (a degradant of thimerosal) and thiols. Such a conformational change could lead to partial or even complete loss of desirable protein function. This study aims to investigate the effects of thimerosal on the capsid stability and antigenicity of recombinant human papillomavirus (HPV) 18 virus-like particles (VLPs). Dramatic destabilization of the recombinant viral capsid upon thimerosal treatment was observed. Such a negative effect on the thermal stability of VLPs preserved with thimerosal was shown to be dependent on the thimerosal concentration. Two highly neutralizing antibodies, 13H12 and 3C3, were found to be the most sensitive to thimerosal treatment. The kinetics of antigenicity loss, when monitored with 13H12 or 3C3 as probes, yielded two distinctly different sets of kinetic parameters, while the data from both monoclonal antibodies (mAbs) followed a biphasic exponential decay model. The potential effect of thimerosal on protein function, particularly for thiol-containing proteinaceous active components, needs to be comprehensively characterized during formulation development when a preservative is necessary. [Display omitted] • Altered antigenicity of thimerosal-treated HPV VLPs was observed with antibodies. • Antigenicity reduction and capsid destabilization were concentration dependent. • The kinetics of epitope-specific antigenicity loss were monitored in real time. • The reduced antigenicity of adjuvant-adsorbed antigens was visualized. [ABSTRACT FROM AUTHOR]

Reactive dyes are the main dyes in printing and dyeing of cellulosic fibers. Reactive dyes fixation rate is a vital indicator to measure the degree of the covalent bond between cellulose and reactive dyes. However, the determination of the fixation rate is tedious and time-consumptive. Based on the theory of reactive dyes dyeing and application of modern computer color matching technology, the relationship between K/S value and the fixation rate with the reactive dyes on cotton fabric was studied. The feasibility of K/S value instead of the traditional washing method for the determination of reactive dyes fixation rate was proved. In this study, the K/S value of the fabric has an excellent linear relationship to the reactive dyes fixation rate obtained by the washing method. The reactive dyes fixation rate can be obtained through the K/S correction value. [ABSTRACT FROM AUTHOR]

Nanocomposite (NC) hydrogels are promising biomaterials that possess versatile properties and functions for biomedical applications such as drug delivery, biosensor development, imaging and tissue engineering. Different strategies and chemistries have been utilized to define the structure and properties of NC hydrogels. In this review, we discuss NC hydrogels synthesized using dynamic bonds, including dynamic covalent bonds (e.g., Schiff base and boronate ester bond) and non-covalent bonds (e.g., hydrogen bonds and metal-ligand coordination). Dynamic bonds can reversibly break and reform to provide self-healing properties to NC hydrogels as well as be influenced by external factors to allow NC hydrogels with stimulus-responsiveness. The presence of dynamic bonds in NC hydrogels can occur at the polymer-polymer or polymer-particle interfaces, which also determines whether the particles act as fillers or crosslinkers in hydrogels. Several representative examples of NC hydrogels fabricated using dynamic bonds are discussed here, focusing on their design, preparation, properties, applications and future prospects. This review provides an overview of the current progress in NC hydrogel development using dynamic bonds, summarizing the material design, fabrication approaches, unique performance and promising biomedical applications. The presence of both nanoparticles and dynamic bonds in hydrogels shows a combined or synergistic effect to provide hydrogels with dynamic features, definable properties, multi-functionality and stimulus-responsiveness for advanced applications. We believe that this review will be of interest to the hydrogel community and inspire researchers to develop next-generation hydrogels. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphene material has a large theoretical specific surface area, excellent theoretical conductivity and mechanical flexibility, and is a promising electrode material for supercapacitors. However, two-dimensional graphene sheets are easy to stack, which affects its electrical properties. Specifically, a sponge-like composite hydrogel for high-performance supercapacitors was prepared by onestep hydrothermal method from activated carbon and graphene oxide. Benefiting from the introduced nitrogen-containing groups and the greatly increased specific surface area, the GAC-2 nitrogen-doped activated carbon/graphene hydrogel electrode showed high specific capacitance of 505.6 F g-1. In addition, the composite hydrogel presented an excellent 3D network structure with abundant internal structural pores, in which graphene and activated carbon were cross-linked by strong covalent bonds. This unique structure greatly improves the mechanical flexibility of the composite electrode (the capacitance retention rate is approximately 87.7% after 500 bending tests). And the self-assembled flexible supercapacitor shows an energy density of 26.9 Wh kg-1 at 242 W kg-1 and outstanding capacitance retention rate of about 92.1% after 5000 charge-discharge cycles, confirming its potential application in supercapacitors. [ABSTRACT FROM AUTHOR]

The cyclo-N6 anion is a total nitrogen unit with higher nitrogen content than cydo-N-5. However, the low decomposition barrier of cyclo-N6 anions hinders its application as a high energy density material (HEDM). Using first-principles calculations, we reveal that the covalent components that enhance the interaction between the cyclo-N6 anion and the cation can effectively improve the stability of cyclo-Né anions. The actinide metals (Th, Pa, U) are selected as suitable cations. Further electronic structure analysis showed that the charge transfer from the actinide metal to cyclo-N6 anions resulted in a strong covalent bond, which promoted the stability of the cyclo-N6 anion in the Th(N6), Pa(N6), and U(N6) structure. This discovery is helpful for the rational design and synthesis of new HEDMs. [ABSTRACT FROM AUTHOR]

Highly concentrated electrolytes (HCEs) are attracting interest as safer and more stable alternatives to current lithium-ion battery electrolytes, but their structure, solvation dynamics and ion transport mechanisms are arguably more complex. We here present a novel general method for analyzing both the structure and the dynamics, and ultimately the ion transport mechanism(s), of electrolytes including HCEs. This is based on automated detection of bonds, both covalent and coordination bonds, including how they dynamically change, in molecular dynamics (MD) simulation trajectories. We thereafter classify distinct local structures by their bond topology and characterize their physicochemical properties by statistical mechanics, giving both a qualitative and quantitative description of the structure, solvation and coordination dynamics, and ion transport mechanism(s). We demonstrate the method by in detail analyzing an ab initio MD simulation trajectory of an HCE consisting of the LiTFSI salt dissolved in acetonitrile at a 1:2 molar ratio. We find this electrolyte to form a flexible percolating network which limits vehicular ion transport but enables the Li+ ions to move between different TFSI coordination sites along with their first solvation shells. In contrast, the TFSI anions are immobilized in the network, but often free to rotate which further facilitates the Li+ hopping mechanism. [ABSTRACT FROM AUTHOR]

Self-healing hydrogels can heal themselves on the damaged sites, which opens up a fascinating way for enhancing lifetimes of materials. Polypeptide/poly(amino acid) is a class of polymers in which natural amino acid monomers or derivatives are linked by amide bonds with a stable and similar secondary structure as natural proteins (α-helix or β-fold). They have the advantages of nontoxicity, biodegradability, and low immunogenicity as well as easy modification. All these properties make polypeptides extremely suitable for the preparation of self-healing hydrogels for biomedical applications. In this review, we mainly focus on the progress in the fabrication strategies of polypeptide-based self-healing hydrogels and their biomedical applications in the recent 5 years. Various crosslinking methods for the preparation of polypeptide-based self-healing hydrogels are first introduced, including host-guest interactions, hydrogen bonding, electrostatic interactions, supramolecular self-assembly of β-sheets, and reversible covalent bonds of imine and hydrazone as well as molecular multi-interactions. Some representative biomedical applications of these self-healing hydrogels such as delivery system, tissue engineering, 3D-bioprinting, antibacterial and wound healing as well as bioadhesion and hemostasis are also summarized. Current challenges and perspectives in future for these "smart" hydrogels are proposed at the end. Polypeptides with the advantages of nontoxicity, biodegradability, hydrophilicity and low immunogenicity, are extremely suitable for the preparation of self-healing hydrogels in biomedical applications. Recently, the researches of polypeptide-based self-healing hydrogel have drawn the great attentions for scientists and engineers. A review to summarize the recent progress in design and biomedical applications of these polypeptide-based self-healing hydrogels is highly needed. In this review, we mainly focus on the progress in fabrication strategies of polypeptide-based self-healing hydrogels and biomedical applications in recent five years and aim to draw the increased attention to the importance of these "smart" hydrogels, facilitating the advances in biomedical applications. We believe this work would draw interest from readers of Acta Biomaterialia. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Tissue adhesion is a severe postoperative complication. Various strategies have been developed to minimize postoperative adhesion, but the clinical efficacy is still far from satisfactory. Herein, we present a dual dynamically crosslinked hydrogel to serve as a physical postoperative anti-adhesion barrier. The hydrogel was generated by dynamic chemical oxime bonding from alkoxyamine-terminated Pluronic F127 (AOP127) and oxidized hyaluronic acid (OHA), as well as hydrophobic association of AOP127. Rheological analysis demonstrated that the hydrogel exhibits temperature sensitivity. At 37 °C, it shows much higher modulus and higher stability than the Pluronic F127 hydrogel. Hemolytic assays suggested that the hydrogel undergoes low hemolysis. In addition, it exhibited anti-adhesion to blood cells in blood cell adhesion tests. It also showed an anti-attachment effect to fibroblasts and biocompatibility in vitro cell studies. Macroscopic evaluation and lap-shear tests revealed that the hydrogel has a moderate adhesive capacity to tissue, which is important for self-fixation. A rat model of sidewall defect-bowel abrasion was established to evaluate the anti-adhesion effect in vivo. The gross observation and pathological analysis revealed a significant reduction in postoperative peritoneal adhesion in the AOP127/OHA hydrogel-treated group than those treated with normal saline or Pluronic F127 hydrogel. Hence, the dual dynamically crosslinked hydrogel with self-fixable capacity may be suitable as a physical barrier for postoperative adhesion prevention. Despite the development of numerous postoperative anti-adhesion barriers, their anti-adhesion efficacy is still limited in clinical trials due to poor tissue adhesion and rapid clearance from injured areas. Herein, we have developed a dual dynamic crosslinked hydrogel, generated by dynamic oxime bonds and hydrophobic interactions. The hydrogel is temperature-sensitive and demonstrates moderate tissue adhesion capacity, which allows for self-fixation when applied to defects. The introduction of dynamic covalent bonds improves the stability of the hydrogel. Moreover, the hydrogel not only displays appropriate hemocompatibility, cytocompatibility and anti-adhesion of blood cells and fibroblasts, but it also effectively contributes to preventing postoperative peritoneal adhesions in vivo. Hence, this dual dynamic crosslinked hydrogel may have potential applications as a physical barrier in clinical practice. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The aim of this research was to identify the color fastness properties of the natural dyes on cotton fabrics using different types of dyes like mehedy/henna, turmeric, tea leaf and pomegranate, which were cheap, easily obtainable and ecofriendly. The findings established that, mehedy/henna dye reacted with cellulose of cotton in alkaline condition to form a permanent covalent bond between the dye and the cellulose, which would not be removed by frequent washing treatment with steaming water in neutral conditions and exposed excellent color fastness properties. Mehedy dye had a reactive group that acted as an integral part of fiber and this covalent bond was formed between the dye molecules and the terminal reactive group. With necessary treatments these dyes were collected from nature in powder form and liquefied them for dyeing on 100% cotton mercerized fabrics with necessary chemicals and auxiliaries as natural dyes had affinity towards cellulosic fibers. Continuous dyeing process was carried out with the facilities of "Pad Dye Pad Steam" machine in open width form and then steamed wash to fix the colors with natural dyestuffs. Dyeing process and color fastness tests were carried out in accordance with the test method provided by AATCC and ISO standards. Dye absorption and color strength tests were conducted with the facilities of lab spectrophotometer "Data Color Spectra Flash SF600" in agreement with Kubelka Monk equation through the spectral reflectance, absorption and scattering characteristics of the samples. "Nicolet IS 50 FTIR" instrument was applied to attain the color intensity properties through the passage of Infrared Radiation (IR) within the spectrum. This research was practice based and the findings were advantageous to the personnel involved in textile industries who were responsible for dyeing the fabrics with natural dyes and to controlling of their color fastness properties. [ABSTRACT FROM AUTHOR]

• Chemically stable covalent organic frameworks were introduced and documented. • Research works on use of COFs as adsorbents in lab tests were reviewed. • Research and development needs for industrial application with COF were discussed. Covalent organic frameworks (COFs) is made by covalent bonding of light elements, such as carbon, oxygen, nitrogen, boron and hydrogen, which can be flexibly synthesized as a porous material with low density, high permanent porosity and controllable sizes. This mini-review outlined the current understandings of mechanisms to yield a chemically stable COF and the use of these COFs to be adsorbents for removing adsorbates from waters. The research and development need to apply the COFs as industrial adsorbetns was discussed. [ABSTRACT FROM AUTHOR]

The use of a screw for repairing defected bones is limited by the dilemma between stiffness, bioactivity and internal fixation ability in current products. For polymer bone screw, it is difficult to achieve the bone stiffness and osteo-induction. Polymer composites may enhance bioactivity and mechanical properties but sacrifice the shape memory properties enormously. Herein, we fabricated a programmable bone screw which is composed of shape memory polyurethane, hydroxyapatite and arginylglycylaspartic acid to resolve the above problem. This composite has significantly improved mechanical and shape-memory properties with a modulus of 250 MPa, a shape fixity ratio of ~90% and a shape recovery ratio of ~96%. Moreover, shape fixity and recovery ratios of the produced SMPC screw in the simulative biological condition were respectively ~80% and ~82%. The produced screw could quickly recover to its original shape in vitro within 20 s leading to easy internal fixation. Additionally, the composite could support mesenchymal stem cell survival, proliferation and osteogenic differentiation in vitro tests. It also promoted tissue growth and showed beneficial mechanical compatibility after implantation into a rabbit femoral intracondyle for 12 weeks with little inflammation. Such bone screw exhibited a fast-fixing, tightened fitting, enhanced supporting and boosted bioactivity simultaneously in the defective bone, which provides a solution to the long-standing problem for bone repairing. We envision that our composite material will provide valuable insights into the development of a new generation of bone screws with good fixation and osteogenic properties. The main obstacles to a wider use of a bone screw are unsatisfied stiffness, inflammatory response and screw loosening issues. Herein, we report a programmable screw with mechanically robust, bioactive and fast-fixing performances. The shape memory polymer composite takes advantage of the component in the natural bone and possesses a stable bush-like structure inside through the covalent bonding, and thus achieve significantly improved mechanical and memory properties. Based on its shape memory effect, the produced screw was proved to offer a recovery force to surroundings and promote the bone regeneration effectively. Therefore, the composite realizes our expectations on functions through structure design and paves a practical and effective way for the development of a new generation of bone screws. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Li+/Ni2+ disorder as an intrinsic structure defect in Ni-based layered oxides cathodes for lithium-ion batteries plays a crucial role on the overall electrochemical performances. However, the nature of Li+/Ni2+ disorder on the structure and property is still poorly understood. Herein, we design and synthesize layered LiNi1/3Co1/3Mn1/3O2 cathode materials with a different Li+/Ni2+ mixing degree, and focus on unveiling the influence mechanism of Li+/Ni2+ disorder on the surface/bulk structural evolution and the charge compensation mechanism by neutron, synchrotron radiation and electrochemical impedance techniques. High Li+/Ni2+ disorder increases the side reactions between electrolyte and electrode surface and aggravates the variation of local environment ofMn cations with (de)lithiating, which is largely responsible for the degradation of the initial capacity, rate capability and cycling performance. Interestingly, Li+/Ni2+ disorder can also relieve the electrostatic interaction between the cationic and anionic ions by enlarging the LiO6 octahedron and TMO6 octahedron, and locks the surrounding oxygen slabs by forming strong covalent bonds between antisite Ni and coordinated O ions, which alleviates the variations of the lattice parameters during charging/discharging. This study presents some new insights into designing high performance layered oxide cathodes through regulating Li+/Ni2+ disorder. [ABSTRACT FROM AUTHOR]

In this study graphene oxide (GO) based active layer was formed on microfiltration substrate to prepared thin file composite forward osmosis (TFC-FO) membrane with high rejection to pesticides. The ideal GO-based membrane should have high stability, durability, and selectivity. To improve the stability of GO based TFC membrane in aqueous solution the GO nanosheets were cross-linked with melamine monomer. An anchoring carbon-nitrogen covalent bond between the GO nanosheets and melamine molecules is thought to supplement to form the nanocomposite structure. As a result of the configuration of melamine molecules within the channel region, a nanocomposite structure has been formed which provides an optimal condition for resisting the flow of hydrated salt ions but creating a pathway for water molecules to flow. According to the FO tests with different draw solutions against DI water feed, the prepared GOM membranes (GO based active layer crosslinked with melamine) showed best performance with trisodium citrate (TSC) draw solution. In the FO model, a water flux of 18.1 LMH was obtained using TSC, which was 970% higher than the NaCl, while the reverse solute diffusion was reduced by 1100%. The effect of GO thickness on FO performance was also studied, by changing GO solution volume during active layer coating (10, 15 and 20 mL GO solution with concentration of 0.1 mg/mL). Result showed that by increasing the GO thickness the water flux increased from 13.7 LMH in GOM.10 to 18.1 in GOM.15. In addition, the nanocomposite membrane shows high rejection against of both diazinon (99.4%) and atrazine (97.3%). In relation to these results, it can be concluded that GO-based membranes can provide clean water in the FO process as an alternative to polymer-based TFC membranes. [Display omitted] • Graphene oxide based membrane fabricated and crosslinked with melamine molecules. • Melamine form covalent bonding with graphene oxide nanosheets. • Crosslinked membrane sohwed high performance and stability in forward osmosis process. • TOCs could be rejected by crosslinked GO membrane. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption of sulfur mustard on Ca 12 O 12 and Ga 12 N 12 was studied by DFT. • The sulfur mustard adsorption on Ga 12 N 12 was stronger than that on Ca 12 O 12. • Ga 12 N 12 may use as work function type sensor of sulfur mustard. This work presents a systematic DFT study of the potential of Ca 12 O 12 and Ga 12 N 12 nanocages for detecting and removing the sulfur mustard. Sulfur mustard was chemically adsorbed on the surface of Ca 12 O 12 and Ga 12 N 12 nanocages. Moreover, the Ga 12 N 12 nanocage exhibited a significantly greater capacity for removing sulfur mustard than Ca 12 O 12 because of stronger sulfur mustard adsorption. QTAIM analysis showed that partial covalent bonds are responsible for the strong sulfur mustard adsorption on Ga 12 N 12 , while sulfur mustard adsorbs on Ca 12 O 12 by strong non-covalent interactions. According to NBO, the work function of Ga 12 N 12 nanocage was considerably reduced exposure to sulfur mustard, indicating that Ga 12 N 12 may be a suitable work function type sensor for detecting sulfur mustard. Comparing the UV–visible spectra of bare nanocages with those of the nanocages adsorbing sulfur mustard revealed that the sulfur mustard adsorption didn't visibly alter the spectra of the nanocages but increased the number of absorption lines. [ABSTRACT FROM AUTHOR]

• In this paper, MnTiO3 nanoparticles doped with g-C3N4 micro-nanosheets were prepared and characterized with good performance using in situ growth method. • MnTiO3/CN can exhibit superior electrochemical hydrogen precipitation performance compared to the mono-material. • The doping of MnTiO3 leads to more nitrogen defects on the surface of g-C3N4, which results in more electrochemically active sites on the surface of the • Prepared heterojunction composite samples, enabling them to make an effective improvement in electrochemical properties. Z-scheme semiconductor heterostructure promotes the practical separation of electron-hole pairs and enhances the carrier separation efficiency, which has broad application prospects in efficient electrocatalytic hydrogen production (HER). However, it remains a significant challenge to construct high-quality directly Z-scheme heterostructure effectively. In this work, the construction of stable and controllable two-dimensional (2D) Z-scheme MnTiO 3 /C 3 N 4 (MTO/CN) heterostructure via In-situ growth strategy is obtained. This strategy relies mainly on the cooperation of ligand covalent bonds arising from the controlled growth of precursors and the tendency of metal ions to acquire stable electronic configurations. Benefiting from the unique electronic structure of heterostructure, the excellent performance of HER based on the MTO/CN heterostructure is systematically investigated. It reveals that the overpotential of the MTO/CN heterostructure is only 357 mV at 10 mA cm2, which is 2.02 times lower compared to the pure g-C 3 N 4. At the same time, the ESCA results show that the value of C dl of the heterostructure is 42.79 mF cm−2, which is 6.26 times higher compared to the pure g-C 3 N 4. Furthermore, this strategy provides new insight and theoretical guidance for the design of the Z-scheme semiconductor heterostructure. Schematic diagram of electrochemical hydrogen precipitation of MnTiO 3 /CN heterojunction composites prepared by in situ growth method. [Display omitted] [ABSTRACT FROM AUTHOR]

Eosin Y (EY) is an organic dye widely used as a photoredox catalyst in organic synthesis, but there are only few studies on its use in heterogeneous photocatalysis for the degradation of aqueous Contaminants of Emerging Concern (CECs). In this context, several synthetic strategies were used to prepare heterogeneous silica-based photocatalysts where EY is anchored to glass wool (GW) covalently or using ionic bonds for obtaining GW-C-EY and GW-I-EY, respectively. The percentage of EY linked to GW-C-EY (up to 0.0034% w/w) was always lower than the obtained in GW-I-EY (0.165% w/w). Photodegradation of CECs such as noscapine (NOS), sulfamethoxazole (SMX) and ofloxacin (OFX) was studied using the new heterogeneous photocatalysts in water under visible light irradiation and results showed that only NOS is photodegraded. It was also observed that EY photoreactivity in GW-C-EY and GW-I-EY is quite similar. Interestingly, when the photocatalysts were studied using mixtures of the three CECs, a synergistic effect that favors the photodegradation of SMX and OFX was observed. Specifically, GW-I-EY achieves 100% photodegradation for NOS and ca. 50% removal of SMX and OFX. Based on photophysical and photochemical experiments, redox processes initiated by an electron transfer from NOS to the EY triplet excited state and the subsequent reaction of the generated EY•− with SMX or OFX justify the observed synergistic photodegradation. This finding opens up the possibility of working with complex aqueous matrices and also of smart selecting the combination of different types of contaminated waters to favor the efficiency of the photocatalytic decontamination processes. [Display omitted] [ABSTRACT FROM AUTHOR]

The penetration of water into rubber-like protein networks such as cross-linked resilin, which is found in insects, can lead to changes in stiffness that range over several orders of magnitude. This softening effect cannot be explained by the volumetric changes associated with pure swelling/deswelling used to describe networks with covalent bonds. Rather, this property stems from the reversible swelling-induced breaking of hydrogen cross-linking bonds that connect the chains in the network. This work presents a model for the swelling and the mechanical response of hydrogen-bond dominated biopolymer networks. It is shown that the penetration of water molecules into the network leads to the breaking of non-covalent cross-linking sites. In turn, the network experiences a reduction in the effective chain-density, an increase in entropy, and a consequent decrease in free energy, thus explaining the dramatic softening. Additionally, the breaking of hydrogen bonds alters the micro-structure and changes the quantitative elastic behavior of the network. The proposed model is found to be in excellent agreement with several experimental findings. The merit of the work is twofold in that it (1) accounts for the number and the strength of non-covalent cross-linking bonds, thus explaining the drastic reduction in stiffness upon water uptake, and (2) provides a method to characterize the micro-structural evolution of hydrogen-bond dominated networks. Consequently, the model can be used as a micro-structural design-guide to program the response of synthetic polymers. Hydrogen-bond dominated biopolymer networks are found in insects and have a unique structure that allows a dramatic reduction of several orders of magnitude in stiffness upon hydration. Understanding the micro-structure of such networks is key in the fabrication of new biomimetic polymers with tunable mechanical properties. This work introduces a microscopically motivated model that explains the dramatic reduction in stiffness and quantifies the influence of key micro-structural quantities on the overall response. The model is validated through several experimental findings. The insights from this work motivate further attempts at the fabrication of new biomimetic polymers and serve as a micro-structural design guide that enables the programming of the elastic swelling-induced response. [ABSTRACT FROM AUTHOR]

Highlights • Schiff base copper complexes immobilized on functionalized GO were successfully synthesized as an ecofriendly system. • Covalent modification of GO through silylation was successfully achieved. • High catalytic activity due to the strong cooperative interaction of GO and the complexes was achieved. • Catalysts can be easily recovered and recycled due to GO support. Abstract We report a straight forward synthesis of a heterogeneous catalyst by covalently immobilizing copper Schiff base complex on the surface of amino functionalized graphene oxide (AGO) for the Suzuki coupling of substituted aryl halides with arylboronic acids. The as-synthesized complex and subsequent catalyst were characterized for their structural features using suitable techniques. The analysis confirmed that the Cu bound to Schiff base (L) ligand via bi(N-,O-) linkage and Cu-L immobilization on AGO was due to its amino functionality. The catalyst exhibited excellent yield of 94% for Suzuki coupling reactions as analyzed by gas chromatography. The catalyst was recycled for 5 successive reactions with insignificant loss in efficiency. ICP-AES analysis showed the catalyst retained 87.5% of its active metal center after 5th iteration. High yield, environmentally benign, easy work-up procedure, easy separation of catalyst and mild reaction conditions are some of the important facets this catalyst offer. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

The purpose of this research was to understand the misconception level of 10th grade students in Yogyakarta province of Indonesia in understanding the concept of ionic and covalent bonds. The ionic and covalent bonds were chosen based on the need assessment on chemistry teachers. This study was inclueded qualitative descriptive research which described the level of students' misconceptions. The sample of this study was 56 students of 10th grade students. The sample was selected by using purposive random sampling technique. The data was collected by three-tier diagnostic test. The data was analysed to determine the percentage of misconception level. The results indicated that the 10th grade students in Yogyakarta suffered misconception with high, medium, and low categories of 19.05%, 42.86%, and 9.52%, respectively. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The seven stable isomers of (BN) 4 cluster were found by using the particle swarm optimization method. • The energy order is R1, R2, R5, R3 at temperature in the range of 0–800 K. • Topological analysis of (BN) 4 cluster indicates that the dominant interaction between B and N is covalent interaction. Abstract We used the particle swarm optimization method to search a variety of isomers of (BN) 4 clusters, and then using the density functional theory of quantum chemistry calculation method to optimize the structures of the chosen isomers at B3LYP/6-31G(d) level. The results show that there are seven configurations are stable stationary points on the potential energy surface. The geometry optimization, infrared spectrum, relative Gibbs free energy, vibrational spectroscopy and topological analysis are implemented for the seven representative clusters. Our results show the diversity of (BN) 4 clusters. The relationship between the structural stability and their symmetry are discussed. We have obtained the lowest energy structure R1 which is the most stable structure, consistent with the previous results. We have also obtained their energy order at different temperatures by calculating the Gibbs free energy. Topological analysis of (BN) 4 cluster indicates that the dominant interaction between B and N is covalent interaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The [3 + 2] cycloaddiiton (32CA) reaction of benzonitrile oxide BNO with 5-methylenehydantoin MH. • Molecular Electron Density Theory (MEDT) perspective at the DFT/B3LYP/6–31 + G(d,p) level of theory. • Topological analysis of the Electron Localization Function (ELF) predicted zwitter-ionic character of BNO and the non-polar character of this 32CA reaction. • The energetically predicted regioselectivity and atropisomerism induced facial selectivity towards anti approach. The [3 + 2] cycloaddition (32CA) reaction of benzonitrile oxide BNO with 5-methylenehydantoin (MH) has been studied with the MEDT perspective at the DFT/B3LYP/6–31 + g(d,p) level of theory. Topological analysis of the ELF shows zwitterionic character of this 32CA reaction and the non-polar character is revealed form the global electron density transfer (GEDT) calculations at the TSs, consistent with the calculated high relative free energies between 27.6 and 39.1 kcal mol−1. The energetically predicted regioselectivity and atropisomerism induced facial selectivity towards anti isomer is in complete agreement with the experimental outcome. The activation energy in this 32CA reaction is associated with the creation of non-bonding electron density at N2 nitrogen and pseudoradical center at C3 and the formation of new C C and C O covalent bonds were not observed at the TSs which was in conformity with the calculated total electron density and the positive Laplacian of electron density at the bond critical points observed at the interatomic bonding regions of the TSs. [ABSTRACT FROM AUTHOR]

In the present work, graphene oxide (GO) was initially prepared by the modified Hummers' method and then surface modification with 3-Methacryloxypropyltrimeth- oxysilane (MPS) was carried out. The silanized GO based polyacrylate (PA) composite emulsion was fabricated via in situ copolymerization. The covalent bonds formed between GO and PA matrix were proposed to improve the dispersion of MPS-GO in composites. FTIR spectra, Raman spectra, XPS and XRD data confirmed that oxidation and modification were occurred, and oxygen-containing functional groups and C C groups were introduced on the side of GO, respectively. Two kinds of structures were observed in composite latexes, and the average diameter of composite latexes (107 nm) was larger than that of PA latexes (87 nm). FTIR spectra also disclosed that reactive MPS-GO had already successfully copolymerized with the PA matrix. AFM images demonstrated that wrinkled GO nanosheets were homogeneously dispersed and incorporated into the PA matrix. The water contact angle (WCA) was found increasing as the addition of MPS-GO, although the composite films exhibited obvious hydrophilicity with increasing the content of MPS-GO. [ABSTRACT FROM AUTHOR]

Enzyme immobilization makes its structure more rigid and insoluble, increasing its stability. This can be done by forming a covalent bond between the enzyme and an inert, insoluble, and preferably low-cost support. Proteases are widely applied in protein hydrolysis; however, most studies focus on the use of proteases in free form. In this work, for the first time, a commercial alkaline protease from Bacillus licheniformis (Protezyn APP 3000) was immobilized by covalent bonding on chitosan modified by glutaraldehyde and ethylenediamine; the immobilized enzyme was applied in the hydrolysis of different proteins sources. The best immobilization conditions observed were as follows: 5% (m/v) chitosan support modified by 5% (v/v) glutaraldehyde diluted in water, immobilization solution with the enzyme diluted in water, and 2 h as immobilization time. Under these conditions, the amount of immobilized enzyme was 69.9%, the efficiency was 33.6% and effectiveness was 48.3%. The biochemical characterization showed that the immobilized enzyme exhibited maximum catalytic activity at the same pH and temperature as the free enzyme (pH 9 and 60 °C); however, the immobilization process extended the optimal temperature range of enzyme activity (50–70 °C). When reused, the immobilized enzyme retained 47.08% of its initial activity after three cycles. The immobilized enzyme showed promise in hydrolyzing casein, hemoglobin, and soy proteins and was more efficient on gelatin than the free enzyme. Therefore, the immobilization performed showed promise in stabilizing a commercial protease that is being studied for the first time and can be optimized to improve the process parameters. [Display omitted] • Protezyn APP 3000, a commercial alkaline protease, was immobilized for the first time. • The immobilized enzyme on chitosan-glutaraldehyde was the most efficient. • The immobilized enzyme obtained good thermal stability and proteolytic performance. • In gelatin hydrolysis, the immobilized enzyme was more efficient than the free form. • The developed immobilization process is promising and can still be optimized. [ABSTRACT FROM AUTHOR]

Non-covalent interaction is believed to play a vital role in stabilizing various complex chemical species. Herein, we have undertaken a theoretical study to understand the nature and extent of non-covalent interaction between the aromatic surfaces of benzene and its substituted derivatives with hydrogen bond donors as well as lone pair containing molecules. Molecular electrostatic potential (MESP) calculation has been used to identify the attractive zones of the aromatic surface. Symmetry adopted perturbation theory (SAPT) calculations reveal that the stability of these interactions is dominated by both electrostatic as well as dispersion interaction. Non-covalent interaction plot (NCI) analysis provided the qualitative visualization of the interaction while quantum theory of atoms in molecules (QTAIM) proved the existence of this interaction through the formation of bond and cage critical points. [ABSTRACT FROM AUTHOR]

Whey protein isolate (WPI) was employed, for the first time, to activate carrageenan (Car) beads for the covalent immobilization of the Aspergillus oryzae β-D-galactosidase (β-gal). These Car beads were subjected to a WPI treatment step followed by a glutaraldehyde (GA) treatment step in order to enable such covalent immobilization. The WPI treatment was optimized via the Box-Behnken Design (BBD). The BBD anticipated that treating the Car beads with a 2.36% WPI solution of pH 5.25 for 7.04 h would allow for the attainment of an immobilized β-gal's activity recovery percent of 34.43%. A verification experiment was accomplished while employing the abovementioned conditions and an immobilized β-gal's activity recovery percent of 34.80 ± 1.11% was attained. It was also shown that the immobilization of β-gal onto the GA-WPI treated Car beads did not alter the enzyme's optimum temperature or optimum pH. Moreover, a reusability study was conducted and 93.84 ± 0.72% of the immobilized β-gal's initial observed activity was preserved during the 13th reusability cycle. [ABSTRACT FROM AUTHOR]

Many fullerenes and carbon nanotubes have the very large electrophilic regions on their molecular surfaces. The existence of these large electrophilic regions is beyond the scope of the concept of the σ-hole and π-hole which were introduced to describe the formation of the noncovalent bonds. The inner cavities of many fullerenes and carbon nanotubes are the regions of positive electrostatic potential, and are electron-withdrawing in character. Our results clearly show that it is the electron-withdrawing cavity not the curvature of the fullerene or carbon nanotube that plays a dominant role for the formation of the large electrophilic regions on the molecular surface. The important role of the large electrophilic regions of fullerenes has been illustrated by using them to successfully explain some experimental observations in crystal engineering. [ABSTRACT FROM AUTHOR]

Supramolecular chemistry as de-ned by Lehn ‘chemistry beyond the molecule’ focuses on the development of functional complex architectures through non-covalent interactions. The year 2017, marked the fiftieth anniversary of the serendipitous discovery of crown ethers. Since then, the field is growing, and due to the efforts of various researchers now it is possible to have some control over the arrangement of things on a small scale. In this review article, the concept of supramolecular chemistry, cooperativity responsible for interactions, techniques for determination of thermodynamic parameters of cooperativity, and the contribution of supramolecular chemistry to nanotechnology is described. [ABSTRACT FROM AUTHOR]