Site-specific N-glycan changes during semen liquefaction.

Normal liquefaction of semen is one of the key steps to ensure the smooth progress of fertilization, and glycosylation has been reported to be involved in the whole process of fertilization. Till now, it is still unclear whether and how glycosylation changes during the liquefaction process of semen. In this study, by performing a glycoproteomic analysis of human semen with the liquefaction process (liquefaction time of semen: 0 min vs 30 min) using our recently developed StrucGP software combined with the Tandem Mass Tags (TMT) based quantification, we identified 25 intact glycopeptides (IGPs) from 10 glycoproteins in semen that were significantly changed during liquefaction, including 23 up-regulated and two down-regulated. Among the 23 up-regulated glycopeptides, half were modified with sialylated glycans, suggesting that sialylated glycans may play a key role in the semen liquefaction process. The data provide an invaluable resource for further studies on the role of glycosylation during semen liquefaction.

Maximal performance of intact N-glycopeptide enrichment using sequential HILIC and MAX columns.

Low abundance and heterogeneity of N-glycosylation at the peptide level poses a great challenge to the structural and functional analysis of glycosylation in the field of glycobiology. Solving this conundrum requires a sufficient and specific method for intact N-glycopeptide enrichment. Using the C18 or HLB desalting column followed by the mixed-mode strong anion exchange (MAX) or hydrophilic interaction chromatography (HILIC) glycopeptide enrichment column are commonly applied approaches for sample preparation of intact N-glycopeptides from complex samples. Herein, we compared the effects of different combinations of two desalting columns and two enrichment columns using equal amounts of mouse brain tissues from the same source. The results revealed the C18 column was a bit superior to the HLB column, and the MAX and HILIC columns were complementary on intact N-glycopeptides enrichment. Additionally, the results also demonstrated that enriching glycopeptides using a HILIC column followed by a MAX column from the flow-through solution got a better enrichment performance than the reversed order. Based on these results, the sequential enrichment of glycopeptides using HILIC and then MAX columns could maximize the enrichment performance of intact N-glycopeptides, and therefore is an option for in-depth analysis of site-specific glycoproteome.

Locality in amino-acid based imidazolium ionic liquids.

Several amino-acid based imidazolium ILs are investigated through the use of ab initio molecular dynamics (AIMD), which includes full polarization. The electric dipole moment distribution and polarization is used as a means of characterizing and understanding these complex systems. Various charge scheme methods were analyzed (Wannier function, Blöchl, Löwdin and Mulliken charge schemes and Voronoi tessellation) to determine their ability to predict dipole moments. These results and the following comparison of methods further deepen the knowledge of polarization by highlighting the importance of the anion and cation separately on polarizability contribution and the need to select a suitable method to predict these. The angular probability distribution is utilized to measure the degree of locality in monopole-dipole electrostatic interactions, which showed no preferential alignment over 700 pm. In addition, the IR and Raman spectra from Voronoi tessellation of [C2C1Im][ala] were analyzed. In these, the strongest signalling peaks showed consistency with experiment and the ability to differentiate between anion and cation components of the IL.

Intermediate Formation of Macrocycles for Efficient Crystallization of 2D Covalent Organic Frameworks with Enhanced Photocatalytic Hydrogen Evolution.

Covalent organic frameworks (COFs) have gained significant attention as key photocatalysts for efficient solar light conversion into hydrogen production. Unfortunately, the harsh synthetic conditions and intricate growth process required to obtain highly crystalline COFs greatly hinder their practical application. Herein, we report a simple strategy for the efficient crystallization of 2D COFs based on the intermediate formation of hexagonal macrocycles. Mechanistic investigation suggests that the use of 2,4,6-triformyl resorcinol (TFR) as the asymmetrical aldehyde build block allows the equilibration between irreversible enol-to-keto tautomerization and dynamic imine bonds to produce the hexagonal ß-ketoenamine-linked macrocycles, the formation of which could provide COFs with high crystallinity in half hour. We show that COF-935 with 3 wt % Pt as cocatalyst exhibit a high hydrogen evolution rate of 67.55 mmol g-1 h-1 for water splitting when exposed to visible light. More importantly, COF-935 exhibits an average hydrogen evolution rate of 19.80 mmol g-1 h-1 even at a low loading of only 0.1 wt % Pt, which is a significant breakthrough in this field. This strategy would provide valuable insights into the design of highly crystalline COFs as efficient organic semiconductor photocatalysts.

Isomeric Oligo(Phenylenevinylene)-Based Covalent Organic Frameworks with Different Orientation of Imine Bonds and Distinct Photocatalytic Activities.

Imine-linked covalent organic frameworks (COFs) have been extensively studied in photocatalysis because of their easy synthesis and excellent crystallinity. The effect of imine-bond orientation on the photocatalytic properties of COFs, however, is still rarely studied. Herein, we report two novel COFs with different orientations of imine bonds using oligo(phenylenevinylene) moieties. The COFs showed similar structures but great differences in their photoelectric properties. COF-932 demonstrated a superior hydrogen evolution performance compared to COF-923 when triethanolamine was used as the sacrificial agent. Interestingly, the use of ascorbic acid led to the protonation of the COFs, further altering the direction of electron transfer. The photocatalytic performances were increased to 23.4 and 0.73 mmol g-1 h-1 for protonated COF-923 and COF-932, respectively. This study provides a clear strategy for the design of imine-linked COF-based photocatalysts and advances the development of COFs.

Recognition of Core-Fucosylated Glycopeptides Based on the Y1+Fuc/Y1 Ratio in Low-Energy HCD Spectra.

Accurate identification of core fucosylation on N-glycopeptides remains challenging due to fucose migration during mass spectrometry analysis. Here, we introduce a simple and straightforward method for core-fucosylated glycopeptide recognition based on the relative intensities of Y1+Fuc ions compared with their corresponding Y1 ions (labeled as Y1+Fuc/Y1 or simply Y1F/Y1 ratio > 0.1) in low-energy HCD-based spectra. The method was first developed by systematically evaluating the influence of fucose migration on the Y1F ion from antenna fucoses based on the distribution of the Y1F/Y1 ratios in the MS/MS spectra of antenna-fucosylated glycopeptides from Fut8-/- mouse brain. The feasibility of the method was then confirmed by using two standard glycoproteins, comparison with glycopeptides in Fut8+/+ mouse brain with/without in silico core-fucosylation removal, and Y1F/Y1 ratio alterations under a lower HCD energy. This method will be applicable to the manual interpretation and software-based high-throughput analysis of core-fucosylated glycopeptides.

Advanced Luminescence Anticounterfeiting Based on Dynamic Photoluminescence and Non-Pre-Irradiation Mechanoluminescence.

Luminescence anticounterfeiting is one of the most significant technologies to protect information security. However, the luminescence of the present anticounterfeiting logo is static, which is easily counterfeited by substitutes, and it always requires an ultraviolet lamp in use, which is inconvenient in application. In this work, according to the present deficiencies of luminescence anticounterfeiting, an interesting phosphor CaZnGe2O6/Mn2+ with unique features of dynamic photoluminescence and non-pre-irradiation mechanoluminescence is developed for the first time. The photoluminescence color of the phosphor can dynamically change from green to red during irradiation, and the non-pre-irradiation mechanoluminescence of the phosphor-based elastomer can be easily stimulated by mechanics such as stretching, bending, or scratching with a finger. By combining the two features of the CaZnGe2O6/Mn2+ phosphor, an advanced dual-mode luminescence anticounterfeiting is designed, and a luminescence logo is fabricated for the anticounterfeiting test. The result demonstrates that this advanced luminescence anticounterfeiting based on the phosphor is not only safer but also more convenient in application.

The Role of Non-Catalytic Domains of Hrp3 in Nucleosome Remodeling.

The Helicase-related protein 3 (Hrp3), an ATP-dependent chromatin remodeling enzyme from the CHD family, is crucial for maintaining global nucleosome occupancy in Schizosaccharomyces pombe (S. pombe). Although the ATPase domain of Hrp3 is essential for chromatin remodeling, the contribution of non-ATPase domains of Hrp3 is still unclear. Here, we investigated the role of non-ATPase domains using in vitro methods. In our study, we expressed and purified recombinant S. pombe histone proteins, reconstituted them into histone octamers, and assembled nucleosome core particles. Using reconstituted nucleosomes and affinity-purified wild type and mutant Hrp3 from S. pombe we created a homogeneous in vitro system to evaluate the ATP hydrolyzing capacity of truncated Hrp3 proteins. We found that all non-ATPase domain deletions (∆chromo, ∆SANT, ∆SLIDE, and ∆coupling region) lead to reduced ATP hydrolyzing activities in vitro with DNA or nucleosome substrates. Only the coupling region deletion showed moderate stimulation of ATPase activity with the nucleosome. Interestingly, affinity-purified Hrp3 showed co-purification with all core histones suggesting a strong association with the nucleosomes in vivo. However, affinity-purified Hrp3 mutant with SANT and coupling regions deletion showed complete loss of interactions with the nucleosomes, while SLIDE and chromodomain deletions reduced Hrp3 interactions with the nucleosomes. Taken together, nucleosome association and ATPase stimulation by DNA or nucleosomes substrate suggest that the enzymatic activity of Hrp3 is fine-tuned by unique contributions of all four non-catalytic domains.

Complexation of Fe(III)/Catechols in atmospheric aqueous phase and the consequent cytotoxicity assessment in human bronchial epithelial cells (BEAS-2B).

Recent research has shown that the complexation of metals-organics plays an important role in atmospheric particulate matter, whose health effects should be taken into account. This work investigates the interactions between catechols (CAs), i.e., 4-nitrocatechol (4NC) and 4-methylcatechol (4MC), and transition metals (i.e., Fe) in the aqueous phase dark reaction. The formation of Fe/CAs complexes and secondary organics products are analyzed by UV-Vis spectroscopy, stopped-flow spectroscopy, high-resolution mass spectrometry and Raman spectroscopy, while the insoluble particulate matter formed from the CAs/Fe mixtures are characterized by the FTIR, X-ray photoelectron spectroscopy (XPS) and thermogravimetric-quadrupole-mass spectrometry (TG-Q-MS). On the basis of the density functional theory (DFT) calculation and experimental results, the possible formation pathways for the complexes of Fe(III) with 4NC (a proxy for organics) are proposed. The Fe/CAs complexes and organics products perhaps have significant sources of light absorption which play an important role in influencing the intensity of atmospheric radiation and particulate phase photochemistry. Besides, the cytotoxicity is tested as a function of concentrations for CAs/Fe mixtures in BEAS-2B cells. Our results show that CAs/Fe mixtures have strong association with cytotoxicity, indicating the mixtures have potential influence to human health.

Enhanced Light-Driven Hydrogen-Production Activity Induced by Accelerated Interfacial Charge Transfer in Donor-Acceptor Conjugated Polymers/TiO2 Hybrid.

Donor-acceptor (D-A) conjugated polymers have proved to be desired candidates to couple with inorganic semiconductors for enhanced photocatalytic activity. Herein, the matched energy levels between polymer BFB and TiO2 make them form BFB-TiO2 composites with moderate photocatalytic H2 evolution rate (HER). To further enhance the interfacial interaction, BFB was modified with a carboxylic acid end group, which reacted with surface OH of TiO2 to form an ester bond. As a result, the functionalized BFBA-TiO2 composites exhibited superior photocatalytic activity. Especially, HER of 4 % BFBA-TiO2 can reach up to 228.2 µmol h-1 under visible light irradiation (λ>420 nm), which is about 2.02 times higher than that of BFB-TiO2 . The enhanced photocatalytic activity originated from the formed ester bond between polymer and TiO2 , and photogenerated electrons injection from lowest unoccupied molecular orbital (LUMO) of the exited polymer to conduction band of TiO2 were accelerated. Therefore, based on an intermolecular interaction mechanism, more suitable D-A conjugated polymers with anchoring groups could be designed to couple with other semiconductors for enhancing photocatalytic activity.

Comparison of σ-/π-Hole Tetrel Bonds between TH3 F/F2 TO and H2 CX (X=O, S, Se).

Several σ-hole and π-hole tetrel-bonded complexes with a base H2 CX (X=O, S, Se) have been studied, in which TH3 F (T=C-Pb) and F2 TO (T=C and Si) act as the σ-hole and π-hole donors, respectively. Generally, these complexes are combined with a primary tetrel bond and a weak H-bond. Only one minimum tetrel-bonded structure is found for TH3 F, whereas two minima tetrel-bonded complexes for some F2 TO. H2 CX is favorable to engage in the π-hole complex with F2 TO relative to TH3 F in most cases, and this preference further expands for the Si complex. Particularly, the double π-hole complex between F2 SiO and H2 CX (X=S and Se) has an interaction energy exceeding 500 kJ/mol, corresponding to a covalent-bonded complex with the huge orbital interaction and polarization energy. Both the σ-hole interaction and the π-hole interaction are weaker for the heavier chalcogen atom, while the π-hole interaction involving F2 TO (T=Ge, Sn, and Pb) has an opposite change. Both types of interactions are electrostatic in nature although comparable contributions from dispersion and polarization are respectively important for the weaker and stronger interactions.

Hydrophilicity-Controlled Conjugated Microporous Polymers for Enhanced Visible-Light-Driven Photocatalytic H2 Evolution.

To take advantage of high surface area of network conjugated microporous polymers, four linear or network conjugated polymers L-PDBT, L-PDBT-O, N-PDBT, and N-PDBT-O are designed in terms of water-compatibility, and it turned out that microporous network N-PDBT-O exhibited the highest hydrogen evolution rate (HER) at 366 µmol h-1 under visible light irradiation (λ > 420 nm, one of best reported pristine polymer-based photocatalysts), which is three times higher than the corresponding linear L-PDBT-O. Water contact angle measurements revealed that benzothiophene-sulfone-based conjugated polymers display better water compatibility and adsorption, and the synergic effect of better hydrophilic surface and higher surface area of N-PDBT-O might eventually lead to more exposed active sites in comparison to linear L-PDBT-O in the H2 evolution suspension system. The hydrophilicity-controlled strategy could be applied to design of other network conjugated microporous polymer photocatalysts in an attempt to improve the activity.

UV/Nitrilotriacetic Acid Process as a Novel Strategy for Efficient Photoreductive Degradation of Perfluorooctanesulfonate.

Perfluorooctanesulfonate (PFOS) is a toxic, bioaccumulative, and highly persistent anthropogenic chemical. Hydrated electrons ( eaq-) are potent nucleophiles that can effectively decompose PFOS. In previous studies, eaq- are mainly produced by photoionization of aqueous anions or aromatic compounds. In this study, we proposed a new photolytic strategy to generate eaq- and in turn decompose PFOS, which utilizes nitrilotriacetic acid (NTA) as a photosensitizer to induce water photodissociation and photoionization, and subsequently as a scavenger of hydroxyl radical (•OH) to minimize the geminate recombination between •OH and eaq-. The net effect is to increase the amount of eaq- available for PFOS degradation. The UV/NTA process achieved a high PFOS degradation ratio of 85.4% and a defluorination ratio of 46.8% within 10 h. A pseudo-first-order rate constant ( k) of 0.27 h-1 was obtained. The laser flash photolysis study indicates that eaq- is the dominant reactive species responsible for PFOS decomposition. The generation of eaq- is greatly enhanced and its half-life is significantly prolonged in the presence of NTA. The electron spin resonance (ESR) measurement verified the photodissociation of water by detecting •OH. The model compound study indicates that the acetate and amine groups are the primary reactive sites.

Comparative Strengths of Tetrel, Pnicogen, Chalcogen, and Halogen Bonds and Contributing Factors.

Ab initio calculations are employed to assess the relative strengths of various noncovalent bonds. Tetrel, pnicogen, chalcogen, and halogen atoms are represented by third-row atoms Ge, As, Se, and Br, respectively. Each atom was placed in a series of molecular bonding situations, beginning with all H atoms, then progressing to methyl substitutions, and F substituents placed in various locations around the central atom. Each Lewis acid was allowed to engage in a complex with NH3 as a common nucleophile, and the strength and other aspects of the dimer were assessed. In the context of fully hydrogenated acids, the strengths of the various bonds varied in the pattern of chalcogen > halogen > pnicogen ≈ tetrel. Methyl substitution weakened all bonds, but not in a uniform manner, resulting in a greatly weakened halogen bond. Fluorosubstitution strengthened the interactions, increasing its effect as the number of F atoms rises. The effect was strongest when the F atom lay directly opposite the base, resulting in a halogen > chalcogen > pnicogen > tetrel order of bond strength. Replacing third-row atoms by their second-row counterparts weakened the bonds, but not uniformly. Tetrel bonds were weakest for the fully hydrogenated acids and surpassed pnicogen bonds when F had been added to the acid.

Baosteel emission control significantly benefited air quality in Shanghai.

As the largest iron and steel producer in China, a part of Baosteel moved out of Shanghai deserves close attention due to its environmental impact. To understand the effect of Baosteel emission control on air quality in Shanghai, daily PM10, PM2.5, SO2, NO2 and CO were measured from 2010 to 2016. Concentrations of pollutants in Baoshan District presented a decreased trend during 2010-2016, with a reduction rate of 28.6% for PM10, 67.3% for SO2, 8.6% for NO2 and 42.0% for CO. However, fine particle pollution in Baoshan District during 2012-2016 seems to become more prominent, with PM2.5 concentration of 47±28, 45±33, 38±24, 54±41 and 51±34µg/m3, respectively, indicating a slight increase of 8.5% in PM2.5. Concentrations of PM10 and CO decreased by 12.5% and 33.8% in the second half year in 2016 (compared with that in 2015) probably due to closure of blast furnace of Baosteel. Baosteel was identified as the largest pollution source in Baoshan District. Emission from Baosteel accounted for 58.0% of SO2, 43.6% of NO2 and 79.3% of dust in total emission from Baoshan District during 2010-2015. Meanwhile, pollutant emission and coal consumption from Baosteel decreased by 52.0% for SO2, 40.1% for NO2, 15.7% for dust and 22% for coal consumption. Energy consumption in Baoshan District reduced by 31% from 2011 to 2015. Air quality improvement in Shanghai was attributed to local emission reduction, together with regional air quality improvement.

Reaction Mechanism of 4-Chlorobiphenyl and the NO3 Radical: An Experimental and Theoretical Study.

Experiment and theoretical chemistry calculations were conducted to elucidate the mechanism of the reaction between 4-chlorobiphenyl (4-CB) and the NO3 radical. The degradation of PCBs was investigated mechanistically through transient absorption spectroscopy technology and high-accuracy theoretical calculation by using 4-CB as the model. Laser flash photolysis (LFP) experiments were performed at 355 nm. The main intermediate was analyzed through transient absorption spectroscopy and identified to be a charge transfer complex (CTC). The final products were identified through GC-MS analysis. The ground states and excited states of the reactants were calculated through density functional theory (DFT) method. The absorption bands at 400 and 700 nm show good agreement with the experimental results. The ratio of absorbance at 400 and 700 nm is 1.6, and the experimental value is 1.8. Analysis of the charge population indicated that one unit charge transfer from 4-CB to NO3. The entire reaction process was divided into two phases. In the first phase, the CTC intermediate was formed by electrostatic attraction between 4-CB and the NO3 radical. In the second phase, the most important channel of subsequent reactions is the σ-complex as an intermediate formed by N-C coupling. The final product 4-chloro,2-nitrobiphenyl was generated with the breakage of BC-H and BN-O, and benzene derivatives were formed by other channels.

Construction of a Fluorescent H2O2 Biosensor with Chitosan 6-OH Immobilized ß-Cyclodextrin Derivatives.

In the present work, a fluorescent H2O2 biosensor was constructed by encapsulating fluorescent probe Rhodamine B (RhmB) in the hydrophobic cavity of the cyclodextrin (ß-CD) and immobilizing catalase (CAT) on the 2-NH2 of chitosan (CTS) in a chitosan 6-OH immobilized ß-cyclodextrin derivative (CTS-6-CD). The inclusion complex of CTS-6-CD to RhmB (CTS-6-CD-RhmB) was prepared by a solution method. Its structure and inclusion efficiency were determined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and fluorescence spectroscopy (FL). CAT was immobilized on CTS-6-CD-RhmB to eventually form the functional membrane, CTS-6-CD-RhmB-CAT, via glutaraldehyde crosslinking, which was further characterized by FTIR and FL, and used as a H2O2 biosensor. The functional membrane was used to simultaneously oxidize and detect H2O2. The detection condition was optimized as pH 8, a reaction temperature of 25 °C, and an immobilized enzyme concentration of 2 × 10-4 mol/L. The fluorescence response of the biosensor exhibited a good linear relationship with the concentration of H2O2 in the range of 20 mΜ-300 µM and the detection limit of 10-8 mol/L.

Preparation, Characterization and Properties of Alginate/Poly(γ-glutamic acid) Composite Microparticles.

Alginate (Alg) is a renewable polymer with excellent hemostatic properties and biocapability and is widely used for hemostatic wound dressing. However, the swelling properties of alginate-based wound dressings need to be promoted to meet the requirements of wider application. Poly(γ-glutamic acid) (PGA) is a natural polymer with high hydrophility. In the current study, novel Alg/PGA composite microparticles with double network structure were prepared by the emulsification/internal gelation method. It was found from the structure characterization that a double network structure was formed in the composite microparticles due to the ion chelation interaction between Ca2+ and the carboxylate groups of Alg and PGA and the electrostatic interaction between the secondary amine group of PGA and the carboxylate groups of Alg and PGA. The swelling behavior of the composite microparticles was significantly improved due to the high hydrophility of PGA. Influences of the preparing conditions on the swelling behavior of the composites were investigated. The porous microparticles could be formed while compositing of PGA. Thermal stability was studied by thermogravimetric analysis method. Moreover, in vitro cytocompatibility test of microparticles exhibited good biocompatibility with L929 cells. All results indicated that such Alg/PGA composite microparticles are a promising candidate in the field of wound dressing for hemostasis or rapid removal of exudates.

Photodegradation of 4-tert-butylphenol in aqueous solution by UV-C, UV/H2O2 and UV/S2O8(2-) system.

The photolytic degradation of 4-tert-butylphenol (4-t-BP) in aqueous solution was investigated using three kinds of systems: UV-C directly photodegradation system, UV/H2O2 and UV/S2O8(2-) system. Under experimental conditions, the degradation rate of 4-t-BP was in the order: UV/S2O8(2-) > UV/H2O2 > UV-C. The reaction kinetics of UV/S2O8(2-) system were thoroughly investigated. The increase of S2O8(2-) concentration enhanced the 4-t-BP degradation rate, which was inhibited when the concentration of S2O8(2-) exceeded 4.0 mM. The highest efficacy in 4-t-BP degradation was obtained at pH 6.5. The oxidation rate of 4-t-BP could be accelerated by increasing the reaction temperature and irradiation intensity. The highest rate constant (kobs = 8.4 × 10(-2) min(-1)) was acquired when the reaction temperature was 45 °C. The irradiation intensity was measured by irradiation distance, and the optimum irradiation distance was 10 cm. Moreover, the preliminary mechanism of 4-t-BP degradation was studied. The bond scission of the 4-t-BP molecule occurred by the oxidation of SO4(•-), which dimerized and formed two main primary products. Under the conditions of room temperature (25 °C ± 1 °C) and low concentration of K2S2O8 (0.5 mM), 35.4% of total organic carbon (TOC) was removed after 8.5-h irradiation. The results showed that UV/S2O8(2-) system was effective for the degradation of 4-t-BP.

Toward a better understanding of Fe(III)-EDDS photochemistry: theoretical stability calculation and experimental investigation of 4-tert-butylphenol degradation.

The present work describes in detail the chemical structure of the complex Fe(III)­EDDS and the predominance of different species with respect to pH. These results were obtained with ab initio calculations. From the photoredox process, the formation of hydroxyl radical was confirmed, and HO(•) is the main species responsible for the degradation of the organic compound present in aqueous solution. The degradation of 4-tert-butylphenol (4-t-BP), used as a model pollutant, was investigated in different conditions. For the first time, the second-order rate constant of the reaction between HO(•) and 4-t-BP and the formation rate of HO(•) (R(HO(•))(f)) from the photochemical process were evaluated. Through the degradation of 4-t-BP, the effect of Fe(III)­EDDS concentration, oxygen, and pH was also investigated. The pH, which plays a role in the iron cycle and in the Fe(III)­EDDS speciation, was noticed as an important parameter for the efficiency of 4-t-BP degradation. Such a result could be explained by taking into account the complex speciation and presence of a predominant form (FeL­) up to pH 8. These results are very useful for the use and optimization of such iron complexes in water treatment processes.