Insights into the enhanced hydrogen adsorption on M/La2O3 (M = Ni, Co, Fe).

Lanthanum oxide (La2O3) possesses superior reactivity during catalytic hydrogenation, but the intrinsic activity of La2O3 toward H2 adsorption and activation remains unclear. In the present work, we fundamentally investigated hydrogen interaction with Ni-modified La2O3. Hydrogen temperature programmed desorption (H2-TPD) on Ni/La2O3 shows enhanced hydrogen adsorption with a new hydrogen desorption peak at a higher temperature position compared to that on the metallic Ni surfaces. By systematically exploring the desorption experiments, the enhanced H2 adsorption on Ni/La2O3 is due to the oxygen vacancies formed at the metal-oxide interfaces. Hydrogen atoms transfer from Ni surfaces to the oxygen vacancies to form lanthanum oxyhydride species (H-La-O) at the metal-oxide interfaces. The adsorbed hydrogen at the metal-oxide interfaces of Ni/La2O3 results in improved catalytic reactivity in CO2 methanation. Furthermore, the enhanced hydrogen adsorption on the interfacial oxygen vacancies is ubiquitous for La2O3-supported Fe, Co, and Ni nanoparticles. Benefiting from the modification effect of the supported transition metal nanoparticles, the surface oxyhydride species can be formed on La2O3 surfaces, which resembles the recently reported oxyhydride observed on the reducible CeO2 surfaces with abundant surface oxygen vacancies. These findings strengthen our understanding of the surface chemistry of La2O3 and shed new light on the design of highly efficient La2O3-based catalysts with metal-oxide interfaces.

The complete chloroplast genome of two Firmiana species and comparative analysis with other related species.

Firmiana is a small genus within the subfamily Sterculioideae of the Malvaceae. There are nine Firmiana species distributed in South and South-west China, most of which are endangered. Due to the shortage of plastid genomes data, the phylogenetic relationships and the evolutionary history of this genus remain unclear. Therefore, the complete chloroplast genomes of F. calcarean and F. hainanensis were sequenced using high-throughput sequencing and then compared with the chloroplast genomes of other reported Firmiana species. The genome size of F. calcarean and F. hainanensis is 161,263 and 160,031 bp long, respectively, containing a total of 131 genes (including 85 protein coding genes, 37 tRNAs, 8 rRNAs, and one pseudogene). Comparative analysis revealed that the genome structure, GC content, gene content and order, as well as the RNA editing sites within the chloroplast genomes of F. calcarean and F. hainanensis were similar to previously reported Firmiana species. ML phylogenetic analysis revealed that F. danxiaensis, F. hainanensis, F. calcarean, F. simplex, and F. major form a sister group to F. colorata, F. pulcherrima, and F. kwangsiensis. The SSRs, long repeats, and 21 highly divergent regions (Pi > 0.01) identified in this study might provide potential DNA markers for further population genetics and phylogenetic studies of Firmiana. Our findings can help design new species-specific molecular markers and the general framework to further explore the evolutionary history of Firmiana and to address their conservation challenges.

Monitoring and Modulating mtDNA G-Quadruplex Dynamics Reveal Its Close Relationship to Cell Glycolysis.

The mitochondrial DNA G-quadruplex (mtDNA G4) is a potential regulatory element for the regulation of mitochondrial functions; however, its relevance and specific roles in diseases remain largely unknown. Here, we engineered a set of chemical probes, including MitoISCH, an mtDNA G4-specific fluorescent probe, together with MitoPDS, a mitochondria-targeted G4-stabilizing agent, to thoroughly investigate mtDNA G4s. Using MitoISCH to monitor previously intractable dynamics of mtDNA G4s, we surprisingly found that their formation was prevalent only in endothelial and cancer cells that rely on glycolysis for energy production. Consistent with this, promotion of mtDNA G4 folding by MitoPDS in turn caused glycolysis-related gene activation and glycolysis enhancement. Remarkably, this close relationship among mtDNA G4s, glycolysis, and cancer cells further allowed MitoISCH to accumulate in tumors and label them in vivo. Our work reveals an unprecedented link between mtDNA G4s and cell glycolysis, suggesting that mtDNA G4s may be a novel cancer biomarker and therapeutic target deserving further exploration.

Effectiveness and Safety of an Inactivated Enterovirus 71 Vaccine in Children Aged 6-71 Months in a Phase IV Study.

BACKGROUND: Evaluation of a licensed inactivated enterovirus type 71 (EV71) vaccine is needed in a phase IV study with a large population to identify its effectiveness and safety for further application. METHODS: An open-label, controlled trial involving a large population of 155 995 children aged 6-71 months was performed; 40 724 were enrolled in the vaccine group and received 2 doses of inactivated EV71 vaccine at an interval of 1 month, and the remaining children were used as the control group. The EV71-infected cases with hand, foot, and mouth disease were monitored in the vaccine and control groups during a follow-up period of 14 months since the 28th day postinoculation through the local database of the Notifiable Infectious Diseases Network. The effectiveness of the vaccine was estimated by comparing the incidence density in the vaccine group versus that in the control group based upon EV71-infected patients identified via laboratory testing. In parallel, the active and passive surveillance for safety of the vaccine was conducted by home or telephone visits and by using the Adverse Event Following Immunization (AEFI) system, respectively. RESULTS: An overall level of 89.7% (95% confidence interval, 24.0-98.6%) vaccine effectiveness against EV71 infection and a 4.58% rate of reported adverse events were observed. Passive surveillance demonstrated a 0.31% rate of reported common minor reactions. CONCLUSIONS: The clinical protection and safety of the EV71 vaccine were demonstrated in the immunization of a large population. CLINICAL TRIALS REGISTRATION: NCT03001986.

Flower-like Hollow MoSe2 Nanospheres as Efficient Earth-Abundant Electrocatalysts for Nitrogen Reduction Reaction under Ambient Conditions.

Electrocatalytic nitrogen reduction reaction (NRR) is a green and sustainable strategy for artificial nitrogen fixation but remains a significant challenge because of the lack of high-performance electrocatalysts. In this study, flower-like hollow MoSe2 nanospheres as efficient earth-abundant NRR electrocatalysts with a high faradaic efficiency of 14.2% and an ammonia yield of 11.2 µg h-1 mgcat.-1 at ambient conditions were prepared. Such excellent NRR activity can be attributed to the higher specific surface area, more active sites, and longer N2 retention time within the shells because of the design of the hollow structure. Density functional theory calculations were performed to further understand the catalytic mechanism involved. This work demonstrates the feasibility of transition-metal selenides as NRR electrocatalysts and suggests an electrocatalyst materials structure design for efficient electrochemical nitrogen fixation.

Development of a Smart Fluorescent Sensor That Specifically Recognizes the c-MYC G-Quadruplex.

The specific sensing of an exact G-quadruplex structure by small molecules has never been reported. A fluorescent sensor based on the photoinduced electron transfer (PeT) mechanism provides possibilities for such specific, one-to-one recognition, indicated by fluorescence. We have rationally developed a PeT fluorescent sensor IZFL-2 by linking triarylimidazole and fluorescein moieties. IZFL-2 is a distinctive, smart sensor whose fluorescence is tunable by its molecular conformations. We then applied IZFL-2 to sensing G-quadruplexes and found that it could exactly distinguish the wild-type c-MYC G-quadruplex from other types of G-quadruplexes, as shown by the activation of its fluorescence. To understand this behavior, we performed various experiments, including fluorescence assays, absorption assays, and multiscale molecular dynamics simulations, to thoroughly investigate the optimal binding mode of IZFL-2 in the c-MYC G-quadruplex. Then, the corresponding HOMO-LUMO of IZFL-2 was analyzed, and the results demonstrated that the PeT process of IZFL-2 is suppressed only in the wild-type c-MYC G-quadruplex via specific loop interactions, which restores its fluorescence. To our knowledge, this smart molecule provides the first example of and new insights into the development of sensors specific for a particular G-quadruplex structure by utilizing intramolecular PeT-controlled fluorescence switching.

Identification of G-Quadruplex-Binding Protein from the Exploration of RGG Motif/G-Quadruplex Interactions.

The arginine/glycine-rich region termed the RGG domain is usually found in G-quadruplex (G4)-binding proteins and is important in G4-protein interactions. Studies on the binding mechanism of RGG domains found that small segments (RGG motif) inside the domain contribute greatly to the G4 binding affinity. However, unlike the entire RGG domains that have been broadly explored, the role of the RGG motif remains obscure, with very limited study. Herein, to clarify the role of the RGG motif in G4-protein interactions, we systematically investigated the binding affinity and mode between RGG-motif peptides and G4s. The internal arrangement of RGG repeats and gap amino acids played a more crucial role in the G4-binding mechanism than a critical number of RGG repeats. Arginines and phenylalanines at the exact position of the RGG motif might enable additional hydrogen bonding and π-stacking interaction with nucleobases and strengthen the binding of G4. Impressively, proceeding from a G4-binding RGG peptide, 12, discovered above, we identified the cold-inducible RNA-binding protein (CIRBP) as a new G4 DNA-binding protein both in vitro and in cells. In addition, we found that the key amino acids for G4 binding in peptide 12 and CIRBP were highly similar, and peptide 12 clearly played a key role in the G4 binding of CIRBP. This report is the first in which a G4-binding protein was identified from exploration of the G4-binding RGG motif. Our findings suggest a novel strategy for discovering new G4-binding proteins by exploring key peptide segments.

[Research on the Efficacy of Fulfillment of Medical Device Adverse Event Monitoring Entities and Safeguard Mechanism].

OBJECTIVES: To solve the problem that medical device adverse event monitoring entities perform their duties inadequately, to provide reference for perfecting the post-market surveillance system. METHODS: Through theoretical and empirical research, the paper explored the ways to improve the performance of monitoring the adverse events of medical devices. RESULTS: The survey found that the number of adverse event monitoring reports was few and the quality of report was poor. The root causes included lack of motivation of monitoring entities, the imperfect monitoring system, and the monitoring capability failure, etc. CONCLUSIONS: The methods such as strengthening the main body responsibility consciousness, establishing evaluation system and accountability system, building social work network, are beneficial to the adverse events monitoring.

Structural analysis of a glycoside hydrolase family 11 xylanase from Neocallimastix patriciarum: insights into the molecular basis of a thermophilic enzyme.

The catalytic domain of XynCDBFV, a glycoside hydrolase family 11 (GH11) xylanase from ruminal fungus Neocallimastix patriciarum previously engineered to exhibit higher specific activity and broader pH adaptability, holds great potential in commercial applications. Here, the crystal structures of XynCDBFV and its complex with substrate were determined to 1.27-1.43 Å resolution. These structures revealed a typical GH11 ß-jelly-roll fold and detailed interaction networks between the enzyme and ligands. Notably, an extended N-terminal region (NTR) consisting of 11 amino acids was identified in the XynCDBFV structure, which is found unique among GH11 xylanases. The NTR is attached to the catalytic core by hydrogen bonds and stacking forces along with a disulfide bond between Cys-4 and Cys-172. Interestingly, the NTR deletion mutant retained 61.5% and 19.5% enzymatic activity at 55 °C and 75 °C, respectively, compared with the wild-type enzyme, whereas the C4A/C172A mutant showed 86.8% and 23.3% activity. These results suggest that NTR plays a role in XynCDBFV thermostability, and the Cys-4/Cys-172 disulfide bond is critical to the NTR-mediated interactions. Furthermore, we also demonstrated that Pichia pastoris produces XynCDBFV with higher catalytic activity at higher temperature than Escherichia coli, in which incorrect NTR folding and inefficient disulfide bond formation might have occurred. In conclusion, these structural and functional analyses of the industrially favored XynCDBFV provide a molecular basis of NTR contribution to its thermostability.

Characterization of gut bacteria at different developmental stages of Asian honey bees, Apis cerana.

Previous surveys have shown that adult workers of the Asian honey bee Apis cerana harbor four major gut microbes (Bifidobacterium, Snodgrassella alvi, Gilliamella apicola, and Lactobacillus). Using quantitative PCR we characterized gut bacterial communities across the life cycle of A. cerana from larvae to workers. Our results indicate that the presence and quantity of these four bacteria were low on day 1, increased rapidly after day 5, and then peaked during days 10-20. They stabilized from days 20-25 or days 25-30, then dropped to a low level at day 30. In addition, the larvae infected by Sacbrood virus or European foulbrood had significantly lower copies of 16S rRNA genes than healthy individuals.

Isotope engineering achieved by local coordination design in Ti-Pd co-doped ZrCo-based alloys.

Deuterium/Tritium (D/T) handling in defined proportions are pivotal to maintain steady-state operation for fusion reactors. However, the hydrogen isotope effect in metal-hydrogen systems always disturbs precise D/T ratio control. Here, we reveal the dominance of kinetic isotope effect during desorption. To reconcile the thermodynamic stability and isotope effect, we demonstrate a quantitative indicator of Tgap and further a local coordination design strategy that comprises thermodynamic destabilization with vibration enhancement of interstitial isotopes for isotope engineering. Based on theoretical screening analysis, an optimized Ti-Pd co-doped Zr0.8Ti0.2Co0.8Pd0.2 alloy is designed and prepared. Compared to ZrCo alloy, the optimal alloy enables consistent isotope delivery together with a three-fold lower Tgap, a five-fold lower energy barrier difference, a one-third lower isotopic composition deviation during desorption and an over two-fold higher cycling capacity. This work provides insights into the interaction between alloy and hydrogen isotopes, thus opening up feasible approaches to support high-performance fusion reactors.

Structural and functional analyses of catalytic domain of GH10 xylanase from Thermoanaerobacterium saccharolyticum JW/SL-YS485.

Xylanases are capable of decomposing xylans, the major components in plant cell wall, and releasing the constituent sugars for further applications. Because xylanase is widely used in various manufacturing processes, high specific activity, and thermostability are desirable. Here, the wild-type and mutant (E146A and E251A) catalytic domain of xylanase from Thermoanaerobacterium saccharolyticum JW/SL-YS485 (TsXylA) were expressed in Escherichia coli and purified subsequently. The recombinant protein showed optimal temperature and pH of 75°C and 6.5, respectively, and it remained fully active even after heat treatment at 75°C for 1 h. Furthermore, the crystal structures of apo-form wild-type TsXylA and the xylobiose-, xylotriose-, and xylotetraose-bound E146A and E251A mutants were solved by X-ray diffraction to high resolution (1.32-1.66 Å). The protein forms a classic (ß/α)8 folding of typical GH10 xylanases. The ligands in substrate-binding groove as well as the interactions between sugars and active-site residues were clearly elucidated by analyzing the complex structures. According to the structural analyses, TsXylA utilizes a double displacement catalytic machinery to carry out the enzymatic reactions. In conclusion, TsXylA is effective under industrially favored conditions, and our findings provide fundamental knowledge which may contribute to further enhancement of the enzyme performance through molecular engineering.

Preliminary X-ray diffraction analysis of thermostable ß-1,4-mannanase from Aspergillus niger BK01.

ß-1,4-Mannanase (ß-mannanase) is a key enzyme in decomposing mannans, which are abundant components of hemicelluloses in the plant cell wall. Therefore, mannan hydrolysis is highly valuable in a wide array of industrial applications. ß-Mannanase isolated from Aspergillus niger BK01 (ManBK) was classified into glycoside hydrolase family GH5. ManBK holds great potential in biotechnological applications owing to its high thermostability. Here, ManBK was expressed and purified in Pichia pastoris and the recombinant protein was crystallized. Crystals belonging to the orthorhombic space group C2221, with unit-cell parameters a=93.58, b=97.05, c=147.84 Å, were obtained by the sitting-drop vapour-diffusion method and diffracted to 1.57 Šresolution. Structure determination using molecular-replacement methods is in progress.

Comparative Ergonomic Study Examining the Work-Related Musculoskeletal Disorder Symptoms of Taiwanese and Thai Workers in a Tape Manufacturing Factory.

This study surveyed 114 Taiwanese and 57 Thai workers in a tape manufacturing factory in Taiwan and evaluated their symptoms of work-related musculoskeletal disorder (WMSD) and associated risk factors by using the revised Nordic Musculoskeletal Questionnaire. Task-appropriate biomechanical and body load assessment tools were also employed to examine biomechanical and body load during four specified daily tasks. The results indicated that the prevalence of discomfort symptoms in any body part within one year was 81.6% for the Taiwanese workers and 72.3% for the Thai workers. The body part in which the Taiwanese workers most frequently experienced discomfort was the shoulders (57.0%), followed by the lower back (47.4%), the neck (43.9%), and the knees (36.8%); where the Thai workers most frequently experienced discomfort was the hands or wrists (42.1%), followed by the shoulders (36.8%) and the buttocks or thighs (31.6%). These locations of discomfort were associated with task characteristics. Heavy-material handling (>20 kg) more than 20 times per day was the most significant risk factor for WMSDs for both groups, and this task must thus be urgently improved. We also suggest that providing wrist braces for Thai workers may assist in alleviating their hand and wrist discomfort. The biomechanical assessment results indicated that the compression forces acting on the workers' lower backs exceeded the Action Limit standard; administrative controls must thus be instituted for two heavy-material handling tasks. In the factory, some tasks and workers' movements when completing these tasks must be assessed and improved immediately by using appropriate tools. Although the Thai workers were engaged in more physically demanding tasks, their WMSDs were milder than those of the Taiwanese workers. The results of the study can serve as references for the prevention and reduction of WMSDs in local and foreign workers in similar industries.

New insights into the process of intrinsic point defects in PuO2.

Intrinsic point defects are known to play a crucial role in determining the physical properties of solid-state materials. In this study, we systematically investigate the intrinsic point defects, including vacancies (VPu and VO), interstitials (Pui and Oi), and antisite atoms (PuO and OPu) in PuO2 using the first-principles plane wave pseudopotential method. Our calculations consider the whole charge state of these point defects, as well as the effect of oxygen partial pressure. This leads to a new perspective on the process of intrinsic point defects in PuO2. We find that the antisite atoms OPu and PuO are more likely to appear in O-rich and O-deficient environments, respectively. Interestingly, the most energetically favorable type of Schottky defect is {2VPu3-: 3VO2+} in an O-rich environment, while {4VO1+: VPu4-} is preferred in an O-deficient environment. These results differ from the commonly known {VPu4-: 2VO2+} type of Schottky defect. Moreover, under O-deficient conditions, we predict that the stable cation Frenkel defect is {VPu4+: Pui4+}, while the most stable anion Frenkel defect is {VO2+: Oi2-} under O-rich conditions. Lastly, we find that the only two types of antisite pairs that can appear are {OPu5-: PuO5+} and {OPu6-: PuO6+}, with the latter being the more stable configuration. These unconventional defect configurations provide a new viewpoint on the process of intrinsic point defects in PuO2 and lay theoretical foundations for future experiments.

Direct observation of highly effective hydrogen isotope separation at active metal sites by in situ DRIFT spectroscopy.

In situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was developed for the first time to observe the hydrogen isotope separation behavior at active CuI sites within CuI-MFU-4l, and clear evidence of the preferential adsorption of D2 over H2 was directly captured. More importantly, our results show direct spectral proof to clarify the chemical affinity quantum sieving mechanism of hydrogen isotope separation within porous adsorbents.

Enhanced activity of Thermotoga maritima cellulase 12A by mutating a unique surface loop.

Cellulase 12A from Thermotoga maritima (TmCel12A) is a hyperthermostable ß-1,4-endoglucanase. We recently determined the crystal structures of TmCel12A and its complexes with oligosaccharides. Here, by using site-directed mutagenesis, the role played by Arg60 and Tyr61 in a unique surface loop of TmCel12A was investigated. The results are consistent with the previously observed hydrogen bonding and stacking interactions between these two residues and the substrate. Interestingly, the mutant Y61G had the highest activity when compared with the wild-type enzyme and the other mutants. It also shows a wider range of working temperatures than does the wild type, along with retention of the hyperthermostability. The k (cat) and K (m) values of Y61G are both higher than those of the wild type. In conjunction with the crystal structure of Y61G-substrate complex, the kinetic data suggest that the higher endoglucanase activity is probably due to facile dissociation of the cleaved sugar moiety at the reducing end. Additional crystallographic analyses indicate that the insertion and deletion mutations at the Tyr61 site did not affect the overall protein structure, but local perturbations might diminish the substrate-binding strength. It is likely that the catalytic efficiency of TmCel12A is a subtle balance between substrate binding and product release. The activity enhancement by the single mutation of Y61G provides a good example of engineered enzyme for industrial application.

Substrate effect on the melting temperature of gold nanoparticles.

Previous experimental, molecular dynamics, and thermodynamic researches on the melting temperature of Au nanoparticles on tungsten substrate provide entirely different results. To account for the substrate effect upon the melting point of nanoparticles, three different substrates were tested by using a thermodynamic model: tungsten, amorphous carbon, and graphite. The results reveal that the melting point suppression of a substrate-supported Au nanoparticle is principally ruled by the free surface-to-volume ratio of the particle or the contact angle between the particle and the substrate. When the contact angle θ is less than 90°, a stronger size-dependent melting point depression compared with those for free nanoparticles is predicted; when the contact angle θ is greater than 90°, the melting temperature of the supported Au nanoparticles are somewhat higher than those for free nanoparticles.

Low Concentration of Quercetin Reduces the Lethal and Sublethal Effects of Imidacloprid on Apis cerana (Hymenoptera: Apidae).

Large-scale use of systemic pesticides has been considered a potential factor for pollinator population decline. Phytochemicals, e.g., quercetin, have been demonstrated to increase the pesticide tolerance of Apis mellifera Linnaeus (Hymenoptera: Apidae), which is helpful to develop strategies to reduce the pesticides hazards to pollinators. In this study, we hypothesized phytochemicals could reduce the detrimental effects of imidacloprid on Apis cerana Fabricius. The lethal and sublethal effects of imidacloprid on A. cerana workers were investigated. The results showed that A. cerana workers chronically exposed to 100 µg/liter imidacloprid had a significantly shorter longevity by 10.81 d compared with control. Acute exposure to imidacloprid at 100 µg/liter impaired the sucrose responsiveness and memory retention of the workers, and 20 µg/liter reduced the sucrose responsiveness. The treatment with 37.8 mg/liter quercetin for 24 h could increase the longevity of A. cerana workers when chronically exposed to 100 µg/liter imidacloprid, and 75.6 mg/liter quercetin feeding treatment alleviated the impairment of sucrose responsiveness. However, workers treated with 151.2 mg/liter and 75.6 mg/liter quercetin had a significantly shorter longevity compared to that of bees chronically exposed to 100 µg/liter imidacloprid without quercetin treatment. Our results suggested that quercetin treatment could produce a biphasic influence on the lethal effects of imidacloprid on A. cerana. Quercetin at 37.8 mg/liter and 75.6 mg/liter in the diet before pesticide exposure was able to reduce the lethal and sublethal effects of imidacloprid, respectively, providing potential strategies to reduce the pesticides hazards to native honey bees (A. cerana).

Adsorption and dissociation behavior of H2 on PuH2 (100), (110) and (111) surfaces: a density functional theory+U study.

The density functional theory (DFT) and DFT plus correction for on-site Coulomb interaction (DFT+U) method were performed to investigate the adsorption and dissociation of H2 on PuH2 (100), (110) and (111) surfaces. Overall, the H2 molecule can be adsorbed on the PuH2 surface without spontaneous dissociation. The calculated H-H bond lengths (R H-H) are all elongated to different degrees, and the R H-H at different adsorption sites is about 0.84-4.21% longer than in the gas phase. We found that the dissociation of H2 on the (110) surface is a spontaneous exothermic process, and a total energy of 0.60 eV is released in the whole process. The smaller barriers corroborate that the migration of an H atom on the PuH2 surface is possible, and even spontaneous diffusion may occur. The spontaneous migration of a hydrogen atom adsorbed on the (110) surface from the surface to the interior promotes the conversion of PuH2 to PuH3, which may be the fundamental driving force of hydrogenation corrosion. Our results provide useful information to explain the mechanism of hydrogenation corrosion on the PuH2 surface.