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In this study, we developed an efficient fluorous tagging strategy for site-selective enzymatic fucosylation/sialylation in which appending a readily removable auxiliary tag (SF17) to the reducing ...

The hydrodynamic response of liquid-filled storage tanks subjected to translational earthquake shaking has been the focus of studies for more than 75 years. In service, tanks experience six components of seismic input, with rocking due to support flexibility and/or rotational components of ground motion. Published theory for predicting hydrodynamic responses in rigid cylindrical tanks due to rotational seismic input is examined. Analytical solutions for pressure in the fluid and on the tank wall, and base moment are modified to account for the effects of angular displacements at the base. A finite element model of a water-filled cylindrical tank using the Arbitrary Lagrangian and Eulerian (ALE) solver in LS-DYNA is used to demonstrate the efficacy of the proposed expressions for three base rocking motions. Results from the modified analytical solutions and the finite element model are in excellent agreement.

Bacteroides fragilis α1,3/4-fucosyltransferase (Bf13FT) was expressed in Escherichia coli and characterized as an α1,3/4-fucosyltransferase that can be used as a versatile catalyst for the synthesi...

In this study, we focused on the synthetic application of α1,3/4-fucosyltransferase obtained from Helicobacter pylori DSM 6709 (FucTIII) on l-fucose-containing glycans. By combining FucTIII with the sequential one-pot enzymatic system of human milk oligosaccharide (HMO) production, various fucosylated HMOs, such as lacto-N-fucopentose V (LNFP V), LNFP VI, lacto-N-difucohexaose II (LNDFH II), and lacto-N-neodifucohexaose II (LNnDFH II), were synthesized. Moreover, l-fucose-containing glycan synthesis of Lewis antigens, such as Lewis x, Lewis y, Lewis a, Lewis b, sialyl Lewis x, sialyl Lewis a, and their derivatives, was achieved. Enzyme kinetics proved that the catalytic efficiency (kcat/Km) of FucTIII on type-2 N-acetyl lactosamine (LacNAc) was 39 times higher than that on type-1 LacNAc. Furthermore, enzyme kinetics revealed that additional GlcNAc on the nonreducing end of the acceptors can enhance the catalytic efficiency of FucTIII on the glycan acceptors. Investigations of bacterial FucTs on substrate ...

In cancers, increased fucosylation (attachment of fucose sugar residues) on cell-surface glycans, resulting from the abnormal upregulation of the expression of specific fucosyltransferase enzymes (FUTs), is one of the most important types of glycan modifications associated with malignancy. Fucosylated glycans on cell surfaces are involved in a multitude of cellular interactions and signal regulation in normal biological processes, as well as in disease. For example, sialyl LewisX is a fucosylated cell-surface glycan that is abnormally abundant in some cancers where it has been implicated in facilitating metastasis, allowing circulating tumor cells to bind to the epithelial tissue within blood vessels and invade into secondary sites by taking advantage of glycan-mediated interactions. To identify inhibitors of FUT enzymes as potential cancer therapeutics, we have developed a novel high-throughput assay that makes use of a fluorogenically labeled oligosaccharide as a probe of fucosylation. This probe, which consists of a 4-methylumbelliferyl glycoside, is recognized and hydrolyzed by specific glycoside hydrolase enzymes to release fluorescent 4-methylumbelliferone, yet when the probe is fucosylated prior to treatment with the glycoside hydrolases, hydrolysis does not occur and no fluorescent signal is produced. We have demonstrated that this assay can be used to measure the inhibition of FUT enzymes by small molecules, because blocking fucosylation will allow glycosidase-catalyzed hydrolysis of the labeled oligosaccharide to produce a fluorescent signal. Employing this assay, we have screened a focused library of small molecules for inhibitors of a human FUT enzyme involved in the synthesis of sialyl LewisX and demonstrated that our approach can be used to identify potent FUT inhibitors from compound libraries in microtiter plate format.

Fluid-structure interaction (FSI) of earthquake shaking is a design consideration in the civil, nuclear, chemical, and mechanical industries. Preliminary sizing of structures and components...

Control of morphology in the synthesis of Rh nanocrystals can be used to precisely tailor the electronic surface structure; this in turn directly influences their performance in catalysis applications. Many works bring attention to the development of Rh nanostructures with low-index surfaces, but limited effort has been placed on the study of high-index and surface-defect-enriched nanocrystals as they are not favored by thermodynamics due to the involvement of high-energy surfaces and increased surface-to-volume ratios. In this work, we demonstrate an aqueous synthesis of concave Rh nanotetrahedra (CTDs) serving as efficient catalysts for energy conversion reactions. CTDs are surface-defect-rich structures that form through a slow growth rate and follow the four-step model of metallic nanoparticle growth. By tuning the surfactant concentration, the morphology of Rh CTDs evolved into highly excavated nanotetrahedra (HETDs) and twinned nanoparticles (TWs). Unlike the CTD surfaces with abundant adatoms and v...

Herein, we report a bifunctional sulfo-fluorous affinity (SOFA) tag-assisted enzymatic synthesis and purification strategy for the facile preparation of bioactive glycans using fluorous solid-phase extraction (FSPE). The incorporation of a sulfonate moiety onto the heavy fluorous tag significantly increases its water solubility, which allows the broad use of the inherently hydrophobic fluorous tag in aqueous buffers. In addition, the SOFA tag contains a photocleavable linker, enabling the easy release of amino-functionalized oligosaccharides by UV irradiation. The SOFA tag was used in the synthesis of both negatively charged and neutral glycans to demonstrate its broad utility as an acceptor toward six different glycosyltransferases, significantly improving the feasibility of the preparation of complex glycans using FSPE. All the reactions were performed in an aqueous buffer, a minimum amount of methanol was used to purify the products, and the SOFA tag was easily recovered after photo-irradiation. Thus, the entire synthetic process is environmentally benign.

The implementation of seismic base isolation can substantially reduce horizontal seismic demands on structures, systems, and components (SSCs) in a nuclear facility, potentially providing significant benefits in terms of increased safety (smaller seismic risk) and reduced capital construction cost. Although increased safety of SSCs has been demonstrated previously, the possible reduction in their capital cost has not been explored. To quantify the reduction in risk enabled by isolation, nonlinear response-history analysis of a conventionally founded and a base-isolated model of a generic nuclear facility (GNF) is performed at the sites of the Idaho National Laboratory and the Los Alamos National Laboratory: sites of moderate and high seismic hazard, respectively. Seismic probabilistic risk assessment is performed to compute the mean annual frequency of unacceptable performance. The seismic risk is reduced by 7 to 8 orders of magnitude by the implementation of isolation. The costs of addressing seismic loadings are estimated for the GNF in both the conventionally founded and base-isolated GNF. The possible reductions in the required seismic ruggedness and in the cost of SSCs in the isolated GNF are quantified at both sites. A reduction in cost enabled by isolation is possible at nearly all sites of nuclear facilities in the United States, with the greatest benefit at sites of high seismic hazard, such as LANL. Two risk-calculation procedures are used in the assessment: a simplified method based on Boolean mathematics and a rigorous method based on Monte Carlo analysis. The simplified procedure, which is suitable for implementation with preliminary design calculations, produces accurate estimates of risk unless the mean annual frequencies of unacceptable performance are very small, measured here as smaller than 10 −10 . The sensitivity of the calculated risk in the conventionally founded GNF, to the choice of anchor period for the seismic hazard curve, is investigated and found to be insignificant over the range considered: 0 to 0.10 s.

Seismic design, qualification, and risk assessment of nuclear safety-related vessels filled with liquid will have to consider the interaction between the vessel (tank), the contained liquid, and submerged components, if any. Seismic fluid-structure-interaction (FSI) analysis of nuclear vessels will rely on numerical models, which are required to be verified and validated. This study validates previously-verified numerical models using test data generated from earthquake-simulator experiments involving a cylindrical tank. Two solvers in LS-DYNA for FSI simulations are used for the numerical analysis: Arbitrary-Lagrangian-Eulerian (ALE) and Incompressible Computational Fluid Dynamics (ICFD). Numerical and test results are compared for responses critical to seismic design of advanced reactor vessels: hydrodynamic pressures on the tank wall, reactions at the support, and wave heights of the contained liquid. Analysis is performed for one-, two-, and three-directional seismic inputs with a range of intensity, and rocking motions. The accuracy of the numerical results and different methods for outputting wave heights are discussed. Recommendations for validation of seismic FSI numerical models of advanced reactors are provided. The validation exercise presented in this study is broadly applicable to cylindrical tanks, regardless of industry sector.

Label-free and rapid detection of pathogenic microorganisms carry an utmost importance for human health as well as environmental monitoring and diagnostics purposes. However, concurrent bacterial detection techniques are either time consuming or associated with expensive reagents and sophisticated equipments. Herein, surface engineered nanoparticles and solid-liquid contact electrification are applied to study the carbohydrate-protein interactions and to develop a self-powered and label-free nanosensor for the detection of Escherichia coli (E. coli) for the first time. D -Mannose functionalized gold nanoparticles (m-Au NPs) and PBS (Phosphate buffer saline) buffer are utilized as the solid triboelectric sensing layer and contact liquid, respectively. The transferred charges generated from the contact electrification of m-Au NPs and PBS result in self-powered electric outputs as signals to investigate the interaction between D -mannose and concanavalin A (Con A). In addition, m-Au NPs also show its ability to specifically recognize the FimH of type 1 pili in E. coli and enable the triboelectric nanosensor (TENS) with selective and sensitive detection towards E. coli. The sensing mechanism has been fully studied and supported in light of surface modification mediated change in interfacial charge transfer phenomena. Attachment of Con A or E. coli decreases the work function of the solid triboelectric sensing layer leading to the enhancement of output voltage and thereby provides the necessary sensing platform. Moreover, the developed TENS shows the reusable potential and can detect E. coli in a wide range from 2 × 104 to 2 × 107 CFU/ml with a limit of detection (LOD) of 4 × 103 CFU/ml. The current work highlights the bright prospect of TENS as a new prototype of sensing technology for label-free and rapid analysis of carbohydrate-protein interactions as well as other pathogenic microorganisms.

Analytical solutions for seismic fluid-structure interaction (FSI) of tanks are used by analysts and engineers for a number of purposes, including preliminary sizing, risk assessment, and verification of numerical models. Analytical solutions for seismic FSI of tanks were first developed in the 1930s and have been extended and/or modified in the following nine decades to accommodate different seismic inputs and boundary conditions. This paper reviews published analytical solutions for rigid and flexible, base-supported, cylindrical tanks subjected to unidirectional horizontal motion of a small amplitude. The studies parsed the fluid-structure (FSI) response into an impulsive and a convective component, and addressed frequencies of lateral motions of the tank (i.e., impulsive frequencies), hydrodynamic pressures, frequencies of waves (i.e., convective frequencies), wave heights, and reactions at the base. The solutions were categorized into exact and approximate solutions based on the methodologies used. Herein, FSI responses are calculated and compared for a range of tank dimensions using the analytical solutions from the different studies. The responses presented here are normalized to be unitless, and can be used for tanks with different dimensions and mechanical properties, and subjected to different input motions. A sample steel water tank is analyzed using the normalized solutions for two earthquake ground motions with different frequency contents. Ignoring tank flexibility may significantly underestimate seismic responses of the tank and its contained fluid. The approximate solutions, which have been widely used for decades, may not be sufficiently accurate in the modern era. Calculation errors in the reviewed studies are identified and corrected, and differences are quantified for the sample tank.

Sialyltransferases of the mammalian ST8Sia family catalyze oligo- and polysialylation of surface-localized glycoproteins and glycolipids through transfer of sialic acids from CMP-sialic acid to the nonreducing ends of sialic acid acceptors. The crystal structure of human ST8SiaIII at 1.85-Å resolution presented here is, to our knowledge, the first solved structure of a polysialyltransferase from any species, and it reveals a cluster of polysialyltransferase-specific structural motifs that collectively provide an extended electropositive surface groove for binding of oligo-polysialic acid chain products. The ternary complex of ST8SiaIII with a donor sugar analog and a sulfated glycan acceptor identified with a sialyltransferase glycan array provides insight into the residues involved in substrate binding, specificity and sialyl transfer.

Herein, we report the first characteriza- tion of a novel galactokinase from Meiothermus tai- wanensis sp. nov. WR-220 (MtGalK), which is over- expressed in E. coli and exhibits a kcat/Km value of 168.47 mM � 1 s � 1 toward Gal at 758C. The thermo- philic MtGalK shows specific substrate recognition toward the Gal configuration with limited tolerance for modifications at the C-2 position to form prod- ucts such as GalN-1-P, GalN3-1-P, and GalNAc-1-P. Due to its unique thermostability toward elevated reaction temperatures, MtGalK served as an ideal biocatalyst in the synthesis of useful sugar-1-phos- phates and was further combined with glucose-1- phosphate thymidylyltransferase (RmlA) and a-1,4- galactosyltransferase (LgtC) to achieve the efficient preparative-scale synthesis of globotriose analogs (Gb3) using a one-pot three-enzyme system. In combination with a chemical synthetic strategy, a carbohydrate antigen from breast cancer stem cells, stage specific embryonic antigen-3 (SSEA-3) pentasaccharide, was synthesized from Gb3 in ten steps with a 23% overall yield. This flexible chemo- enzymatic strategy for the synthesis of SSEA-3 also allowed us to further expand the inventory of valua- ble natural and non-natural glycans.

Magnetic nanoparticles (MNPs) are attractive materials that serve as a support for enzyme immobilization and facilitate separations by applying an external magnetic field; this could facilitate the recycling of enzymes and broaden their applications in organic synthesis. Herein, we report the methods for the immobilization of water-soluble and membrane-bound enzymes, and the activity difference between free and immobilized enzymes is discussed. Sialyltransferase (PmST1, from Pasteurella multocida ) and cytidine monophosphate (CMP)-sialic acid synthetase (CSS, from Neisseria meningitides ) were chosen as water-soluble enzymes and expressed using an intein expression system. The enzymes were site-specifically and covalently immobilized on PEGylated-N-terminal cysteine MNPs through native chemical ligation (NCL). Increasing the length of the PEG linker between the enzyme and the MNP surface increased the activity of the immobilized enzymes relative to the free parent enzymes. In addition, the use of a fluorescent acceptor tag for PmST1 affected enzyme kinetics. In contrast, sialyltransferase from Neisseria gonorrheae (NgST, a membrane-bound enzyme) was modified with a biotin-labeled cysteine at the C-terminus using NCL, and the enzyme was then assembled on streptavidin-functionalized MNPs. Using a streptavidin-biotin interaction, it was possible to immobilize NgST on a solid support under mild ligation conditions, which prevented the enzyme from high-temperature decomposition and provided an approximately 2-fold increase in activity compared to other immobilization methods on MNPs. Finally, the ganglioside GM3-derivative (sialyl-lactose derivative) was synthesized in a one-pot system by combining the use of immobilized PmST1 and CSS. The enzymes retained 50% activity after being reused ten times. Furthermore, the results obtained using the one-pot two-immobilized-enzyme system demonstrated that it can be applied to large-scale reactions with acceptable yields and purity. These features make enzyme-immobilized MNPs applicable to organic synthesis.

In this study, we describe the direct synthe- sis of uridine 5'-diphosphate galactose (UDP-Gal) by a wild-type bacterial thymidylyltransferase (RmlA), which is used to synthesize thymidine 5'-diphosphate glucose (TDP-glucose) in nature. By using magnesi- um (Mg 2+ ) as a cofactor and a reaction temperature of 558C, a one hundred milligram-scale synthesis of UDP-Gal was achieved by RmlA. In addition, RmlA was site-specifically and covalently immobilized on magnetic nanoparticles (MNPa) The resulting RmlA-MNP complex retained almost 95% of its ac- tivity after reuse in ten consecutive enzyme assays. Furthermore, b-1,4-galactosyltransferase (GalT) from Neisseria meningitides was successfully overex- pressed and purified by using an intein-mediated protein expression system. GalT was relatively stable at 258C, and its activity was enhanced in the pres- ence of DTT and BSA. Thus, it was feasible to syn- thesize N-acetyllactosamine (LacNAc) using RmlA and GalT in a sequential addition of enzyme and ad- justment of thereaction temperature. These results demonstrate the potential applications of bacterial RmlA in carbohydrate synthesis.

The Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ and Li + -doped Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ phosphors were prepared by solid-state reaction process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) as well as lifetimes, was utilized to characterize the resulting phosphors. Under the excitation of ultraviolet light, the Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ and Li + -doped Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ show the characteristic emissions of Eu 3+ ( 5 D 0 – 7 F 1,2,3 transitions dominated by 5 D 0 – 7 F 1 at 593 nm) and Dy 3+ ( 4 F 9/2 – 6 H 15/2 , 13/2 transitions dominated by 4 F 9/2 – 6 H 15/2 at 494 nm), respectively. The incorporation of Li + ions into the Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ phosphors has enhanced the PL intensities depending on the doping concentration of Li + , and the highest emission was obtained in Ba 2 Gd 0.9 NbO 6 : 0.10Eu 3+ , 0.01Li + and Ba 2 Gd 0.95 NbO 6 : 0.05Dy 3+ , 0.07Li + , respectively. An energy level diagram was proposed to explain the luminescence process in the phosphors.

The design of high-affinity lectin ligands is critical for enhancing the inherently weak binding affinities of monomeric carbohydrates to their binding proteins. Glyco-gold nanoparticles (glyco-AuNPs) are promising multivalent glycan displays that can confer significantly improved functional affinity of glyco-AuNPs to proteins. Here, AuNPs are functionalized with several different carbohydrates to profile lectin affinities. We demonstrate that AuNPs functionalized with mixed thiolated ligands comprising glycan (70 mol %) and an amphiphilic linker (30 mol %) provide long-term stability in solutions containing high concentrations of salts and proteins, with no evidence of nonspecific protein adsorption. These highly stable glyco-AuNPs enable the detection of model plant lectins such as Concanavalin A, wheat germ agglutinin, and Ricinus communis Agglutinin 120, at subnanomolar and low picomolar levels through UV/Vis spectrophotometry and dynamic light scattering, respectively. Moreover, we develop in situ glyco-AuNPs-based agglutination on an oriented immobilized antibody microarray, which permits highly sensitive lectin sensing with the naked eye. In addition, this microarray is capable of detecting lectins presented individually, in other environmental settings, or in a mixture of samples. These results indicate that glyconanoparticles represent a versatile and highly sensitive method for detecting and probing the binding of glycan to proteins, with significant implications for the construction of a variety of platforms for the development of glyconanoparticle-based biosensors.

According to the seismic risk assessment results presented in the Final Safety Analysis Report (FSAR) for a nuclear power plant in Taiwan, the failure of Residual Heat Removal (RHR) piping system occurs in both of the two accident sequences with the highest contributions for core damage. The seismic performance of RHR piping system depends on the capacity of its components, such as supports, flanged joints and reducers. For the need of seismic response-history analysis of RHR piping systems, we developed detailed numerical models of flanged joint and reducer using finite element analysis software (ABAQUS and SAP2000). The proposed finite element models were verified by the experimental results. The pure bending tests with four-point cyclic loading were conducted for sample flanged joint and reducer to investigate their mechanical behaviors. The displacement and rotation responses identified from the tests are in good agreement with the results of numerical analysis. A preliminary simplified model of flanged joints was also proposed in this study to improve the efficiency of numerical analysis for RHR piping system.Copyright © 2014 by ASME

Seismic probabilistic risk assessment (SPRA) has been widely used to compute the frequencies of core damage and release of radiation of a nuclear power plant (NPP). In 2011, Huang et al. (2011a, 2011b) published a SPRA methodology with the following characteristics different from the widely used Zion method: (a) seismic fragility curves are defined as a function of structural response parameters, such as floor spectral acceleration and story drift; (b) nonlinear response-history analysis is used to estimate statistical distributions of seismic demands for structural and non-structural components of NPPs; (c) Monte Carlo simulation is used to determine damage states of structural and non-structural components. In the study presented in this paper, the seismic risk of a sample NPP was evaluated using the methodology of Huang et al. (2011a, 2011b). The seismic risk was quantified using the annual frequency of unacceptable performance defined by a sample accident sequence for a sample NPP. The values of seismic risk computed using the methodology of Huang et al. (2011a, 2011b) and Boolean Algebra were compared to evaluate the accuracy and efficiency of the methodology of Huang et al. (2011a, 2011b). The two procedures generate similar risk values and the methodology of Huang et al. (2011a, 2011b) is more efficient than the procedure using Boolean Algebra.Copyright © 2014 by ASME

Sialic acids are a diverse family of negatively charged monosaccharides with a shared nine-carbon carboxylated backbone, and they often serve as the terminal positions of cell surface glycoproteins and glycolipids. Sialic acids play essential roles in mediating or modulating numerous pathological, biological, and immunological recognition events. Advances in synthesis have provided chemically well-defined and structurally homogeneous sialic acid-containing carbohydrates that are crucial for studying glycobiology. This review highlights recent innovations in the chemical and chemoenzymatic synthesis of difficult α-sialosides, with a particular focus on methods developed for α-selective sialylation in the synthesis of O-linked and S-linked oligosialic acids.

We designed a novel strategy for sensitively detecting the activity of α-2,8-polysialyltransferase (PST) by a combination of ganglioside GD3 functionalized gold nanoparticles and inactive endosialidase. We anticipate that this new method will facilitate the search for PST inhibitors as well as for improved mutant forms of PST in directed evolution experiments.

Sialic acids are a diverse family of negatively charged monosaccharides with a shared nine-carbon carboxylated backbone, and they often serve as the terminal positions of cell surface glycoproteins and glycolipids. Sialic acids play essential roles in mediating or modulating numerous pathological, biological, and immunological recognition events. Advances in synthesis have provided chemically well-defined and structurally homogeneous sialic acid-containing carbohydrates that are crucial for studying glycobiology. This review highlights recent innovations in the chemical and chemoenzymatic synthesis of difficult α-sialosides, with a particular focus on methods developed for α-selective sialylation in the synthesis of O-linked and S-linked oligosialic acids.

Polysialyltransferases (PSTs) assemble polysialic acid (PSA) and have been implicated in many biological processes. For example, certain bacteria such as neuroinvasive Neisseria meningitidis decorate themselves in a PSA capsule to evade the innate immune system. Identifying inhibitors of PSTs therefore represents an attractive therapeutic goal and herein we describe a high-throughput, robust, and sensitive microtiter-plate-based activity assay for PST from N. meningitidis. A trisialyl lactoside (GT3) serving as the acceptor substrate was immobilized on a 384-well plate by click chemistry. Incubation with PST and CMP-sialic acid for 30min resulted in polysialylation. The immobilized PSA was then directly detected using a green fluorescent protein (GFP)-fused PSA-binding protein consisting of the catalytically inactive double mutant of an endosialidase (GFP-EndoNF DM). We report very good agreement between kinetic and inhibition parameters obtained with our on-plate assay versus our in-solution validation assay. In addition we prove our assay is robust and reliable with a Z' score of 0.79. All aspects of our assay are easily scalable owing to optimization trials that allowed immobilization of acceptor substrates prepared from crude reaction mixtures and the use of cell lysates. This assay methodology enables large-scale PST inhibitor screens and can be harnessed for directed evolution screens.

A straightforward method for fabricating a stable and covalent carbohydrate microarray based on boronate formation between the hydroxyl groups of carbohydrate and boronic acid (BA) on the glass surface was used to identify carbohydrate–protein interactions.

The Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ and Li + -doped Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ phosphors were prepared by solid-state reaction process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) as well as lifetimes, was utilized to characterize the resulting phosphors. Under the excitation of ultraviolet light, the Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ and Li + -doped Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ show the characteristic emissions of Eu 3+ ( 5 D 0 – 7 F 1,2,3 transitions dominated by 5 D 0 – 7 F 1 at 593 nm) and Dy 3+ ( 4 F 9/2 – 6 H 15/2 , 13/2 transitions dominated by 4 F 9/2 – 6 H 15/2 at 494 nm), respectively. The incorporation of Li + ions into the Ba 2 GdNbO 6 : Eu 3+ /Dy 3+ phosphors has enhanced the PL intensities depending on the doping concentration of Li + , and the highest emission was obtained in Ba 2 Gd 0.9 NbO 6 : 0.10Eu 3+ , 0.01Li + and Ba 2 Gd 0.95 NbO 6 : 0.05Dy 3+ , 0.07Li + , respectively. An energy level diagram was proposed to explain the luminescence process in the phosphors.

The Cu(I)-catalyzed alkyne−azide [2 + 3] cycloaddition has been demonstrated to be an effective and orthogonal conjugation reaction to covalently immobilize biomolecules on magnetic nanoparticles (MNPs). The azido group on the MNP surface provides better conjugation efficiency with alkynated molecules. Moreover, the C-terminal alkynated protein was site-specifically immobilized on MNP. The protein binding activity presented by site-specific immobilization is higher than that by random amide bond formation.

Through the native chemical ligation, CMP-sialic acid synthetase (CSS) was site-specifically immobilized on magnetic nanoparticles and presented excellent enzymatic performance.