Bio-enrichment of heavy metals U(VI) in wastewater by protein DSR A.

Uptaking U(VI) from the environment by biological method is an environmental friendly and efficient way. In this work, we have acquired and isolated the protein DSR A by genetic engineering, then assessed its capacity and mechanisms to absorb U(VI) from wastewater. As results, we proved that protein DSR A can precisely recognize, enrich and remove uranyl ions in simulated wastewater solution. Its great removal potential was demonstrated in the adsorption experiments, the adsorption capacity of protein DSR A can reach 182.3 mg/g in the condition at 10 mg/L U(VI) and pH = 6. The Langmuir isotherm model and the pseudo-first-order kinetic equation were used to better describe the absorption process. We can confirm that Na+, Sr2+ and K+, these three metal ions have less effect on the enrichment of U(VI) by protein DSR A compared with other common cations. Besides, we can educe some mechanisms for the removal of U (VI) by protein DSR A from the results of FTIR, SEM-EDS, XPS (binding energy = 2.0 ~ 4.0ke V), MAP and XRD analysis before and after adsorption. This work has demonstrated the great potential of genetic engineering and biological methods in dealing with environmental heavy ion pollution.

Preparation of ZnNiAl-LDHs microspheres and their adsorption behavior and mechanism on U(VI).

Ternary zinc-nickel-aluminum hydrotalcites (ZnNiAl-LDHs) were prepared by hydrothermal synthesis. The structure and morphology of the materials were characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), nitrogen adsorption-desorption (BET) and other test techniques. ZnNiAl-LDHs was applied in the treatment of uranium-containing wastewater, the effects of initial pH of the solution, adsorption temperature and contact time on its adsorption performance were systematically investigated, and the adsorption performance of ZnNiAl-LDHs and ZnAl-LDHs on uranyl ions were compared. The result showed that ZnNiAl-LDHs were 3D microspheres self-assembled from flakes, with a specific surface area of 102.02 m2/g, which was much larger than that of flake ZnAl-LDHs (18.49 m2/g), and the saturation adsorption capacity of ZnNiAl-LDHs for uranyl ions (278.26 mg/g) was much higher than that of ZnAl-LDHs for uranyl ions (189.16 mg/g), so the ternary ZnNiAl-LDHs had a more excellent adsorption capacity. In addition, kinetic and thermodynamic studies showed that the adsorption process of ZnNiAl-LDHs on uranyl ions conformed to the pseudo-second-order kinetic model and Langmuir isotherm model. The positive value of ΔH and the negative value of ΔG indicated that the adsorption process was endothermic and spontaneous. The adsorption mechanism was analyzed by X-ray energy spectroscopy (EDS), fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results showed that the adsorption of uranyl ions by ZnNiAl-LDHs mainly consisted of complexation and ion substitution. The research results prove that ZnNiAl-LDHs is an adsorbent with low cost and excellent performance, and it has a good application prospect in the field of uranium-containing wastewater treatment.

Mechanism of recombinant bacteria adsorb UO22+ under culture condition.

Research on the ability and mechanism of genetically recombinant E. coli DH5α containing DSR A gene to enrich uranium under culture conditions provides a theoretical basis for the application of the bacteria in the treatment of uranium pollution. By exploring the influence of factors such as the initial concentration of uranium, culture time, and inoculation amount on the characteristics of uranium enrichment in genetically recombinant E. coli, using FTIR, SEM-EDS, XPS and XRD explore the mechanism of uranium-enriched bacteria. The results showed that when initial UO22+ concentration reach 600 mg/L, E. Coli D1 could not survived, indicated that the maximum tolerance concentration is lower than 600 mg/L. While concentration between 0∼500 mg/L, strains D1 can grow normally and has the ability to enrich uranium. In the prime stage, strains D1 resist toxics through release inorganic phosphates to precipitate UO22+ on cell wall, after 96 h, most UO22+ were transferred into cytoplasm and metabolized into U(IV) which is less toxic. In the metabolize process, all groups involved in metabolizing UO22+, especially protein contain groups like hydroxyl, amine and carboxyl paly a huge role. It shows that within a certain concentration rage, strains D1 has a good enrichment effect on uranium under culture conditions.

Ordered Ti-doped FeVO4 nanoblock photoanode with improved charge properties for efficient solar water splitting.

Highly photoactive FeVO4 photoanodes with ordered nanoblock morphology and uniform Ti-doping were prepared by drop-casting mixed Ti and V precursors onto FeOOH nanorod films and following an annealing process. The results indicate that Ti4+ is uniformly doped into the FeVO4 lattice by substituting V5+ and provides an increased number of O2- vacancies. The optimized film thickness and doping level are 620 nm and 0.3%, respectively. Compared to the undoped sample, the Ti-doped photoanode showed ~ 219% enhancement in photocurrent at 1.0 V vs Ag/AgCl under back illumination of AM 1.5, reaching a state-of-the-art value of ~ 1.47 mA cm-2, and also achieved stable and efficient overall water splitting activity with evolution rates of 28.3 and 14.1 µmol cm-2h-1 for H2 and O2, respectively. The excellent PEC performance could be attributed to the remarkably enhanced charge carrier concentration and conductivity, and the facilitated charge transfer kinetics across the semiconductor/electrolyte interface, as a result of Ti-doping.

A Porous Aromatic Framework Functionalized with Luminescent Iridium(III) Organometallic Complexes for Turn-On Sensing of 99TcO4.

Contamination of 99TcO4-, a problematic radioactive anion in the nuclear fuel cycle, in groundwater has been observed in a series of legacy nuclear sites, representing a notable radiation hazard and environmental concern. The development of convenient, rapid, and sensitive detection methods is therefore critical for radioactivity control and remediation tasks. Traditional detection methods suffer from clear demerits of either the presence of large interference from coexisting radioactive species (e.g., radioactivity counting methods) or the requirement of extensive instrumentation and analysis procedure (e.g., mass spectrometry). Here, we constructed a luminescent iridium(III) organometallic complex (Ir(ppy)2(bpy)+; ppy = 2-phenylpyridine, bpy = 2,2'-bipyridine)-grafted porous aromatic framework (Ir-PAF) for the first time, which can be utilized for efficient, facile, and selective detection of trace ReO4-/TcO4- in aqueous solutions. Importantly, the luminescence intensity of Ir-PAF is greatly enhanced in the presence of ReO4-/TcO4-, giving rise to a distinct turn-on sensor with the detection limit of 556.9 µg/L. Such a superior detection capability originates from the highly selective and strong interaction between ReO4-/TcO4- and Ir(ppy)2(bpy)+, leading to an efficient pre-enrichment of ReO4-/TcO4- during analysis and subsequently a much weaker nonradiative decay of the luminescence of Ir(ppy)2(bpy)+, as illustrated by density functional theory (DFT) calculation as well as quantum yield and fluorescence lifetime measurements. Successful quantification of trace ReO4- in simulated Hanford low-activity waste (LAW) solution containing large excess of Cl-, NO3-, and NO2- was demonstrated, highlighting the bright future of luminescent PAFs in the area of chemical sensing.

Prognosis in triple-negative apocrine carcinomas of the breast: A population-based study.

BACKGROUND: Triple-negative apocrine carcinoma (TNAC) of the breast is a very rare type of breast cancer. Furthermore, the clinicopathological features, prognosis, and potential impact of treatment strategies in TNAC remain unclear. METHODS: Data from the Surveillance, Epidemiology, and End Results (SEER) program were used to identify breast cancer patients diagnosed between 2010 and 2016 with TNAC and triple-negative breast cancer (TNBC, IDC [invasive ductal carcinoma], NOS [not otherwise specified]). Chi-squared tests were used to examine the categorical variables between the two groups. Overall survival (OS) of TNAC and TNBC was assessed by Kaplan-Meier analyses and Cox regression. Breast cancer-specific survival (BCSS) was evaluated by Nelson-Aalen analyses and competing risk regression. RESULTS: We identified 31 362 patients from the SEER database, including 366 patients with TNAC and 30 996 patients with TNBC. TNAC was correlated with older age, lower T stage and lower tumor grade. Patients with TNAC had better OS compared with TNBC patients; the 5-year OS rates were 82.2% vs 73.5% (P < .001). The breast cancer-related death rate was significantly lower in patients with TNAC than in patients with TNBC, with a 5-year cumulative incidence of 9.1% vs 22.9% (P < .001). Chemotherapy was significantly associated with improved OS in TNAC patients, but radiotherapy was not associated with OS in TNAC patients. In the multivariable Cox regression, TNAC was still associated with improved OS (HR [hazard ratio], 0.61; 95% CI [confidence interval] 0.45-0.83; P = .002). In the multivariable competing risk regression, the significantly higher BCSS in patients with TNAC compared patients with TNBC remained (subdistribution HR [SHR], 0.42; 95% CI, 0.27-0.64; P < .001). CONCLUSION: Patients with TNAC had a better prognosis than patients with TNBC, and chemotherapy was associated with survival advantages in TNAC patients.

Predicting Thermodynamic Properties of PBXTHs with New Quantum Topological Indexes.

Novel group quantitative structure-property relationship (QSPR) models on the thermodynamic properties of PBXTHs were presented, by the multiple linear regression (MLR) analysis method. Four thermodynamic properties were studied: the entropy (Sθ), the standard enthalpy of formation (ΔfHθ), the standard Gibbs energy of formation (ΔfGθ), and the relative standard Gibbs energy of formation (ΔRGθ). The results by the formula indicate that the calculated and predicted data in this study are in good agreement with those in literature and the deviation is within the experimental errors. To validate the estimation reliability for internal samples and the predictive ability for other samples, leave-one-out (LOO) cross validation (CV) and external validation were performed, and the results show that the models are satisfactory.

Direct Visualization of Catalytically Active Sites at the FeO-Pt(111) Interface.

Within the area of surface science, one of the "holy grails" is to directly visualize a chemical reaction at the atomic scale. Whereas this goal has been reached by high-resolution scanning tunneling microscopy (STM) in a number of cases for reactions occurring at flat surfaces, such a direct view is often inhibited for reaction occurring at steps and interfaces. Here we have studied the CO oxidation reaction at the interface between ultrathin FeO islands and a Pt(111) support by in situ STM and density functional theory (DFT) calculations. Time-lapsed STM imaging on this inverse model catalyst in O2 and CO environments revealed catalytic activity occurring at the FeO-Pt(111) interface and directly showed that the Fe-edges host the catalytically most active sites for the CO oxidation reaction. This is an important result since previous evidence for the catalytic activity of the FeO-Pt(111) interface is essentially based on averaging techniques in conjunction with DFT calculations. The presented STM results are in accord with DFT+U calculations, in which we compare possible CO oxidation pathways on oxidized Fe-edges and O-edges. We found that the CO oxidation reaction is more favorable on the oxidized Fe-edges, both thermodynamically and kinetically.

Adsorbate diffusion on transition metal nanoparticles.

Diffusion of adsorbates on transition metal nanoparticles is a precursor process for heterogeneously catalyzed reactions, and as a result, an atomistic understanding of the diffusion mechanism is very important. We systematically studied adsorption and diffusion of atomic and diatomic species (H, C, N, O, CO, and NO) on nanometer-sized Pt and Cu nanoparticles with different sizes and shapes using density functional theory calculations. We show that nanoparticles bind adsorbates more strongly than the corresponding extended single crystal metal surfaces. We find that there is a Brønsted-Evans-Polanyi-type linear correlation between the transition state energy and the initial state energy for adsorbate diffusion across the edges of Pt and Cu nanoparticles. We further show that the barrier for adsorbate diffusion across the nanoparticles edges can be estimated by the binding energy of the adsorbate on the nanoparticles. These results provide useful insights for understanding diffusion-mediated chemical reactions catalyzed by transition metal nanoparticles, which are widely used in heterogeneous catalysis.

Water clustering on nanostructured iron oxide films.

The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule-molecule and molecule-surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moiré-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moiré structure.

Significant quantum effects in hydrogen activation.

Dissociation of molecular hydrogen is an important step in a wide variety of chemical, biological, and physical processes. Due to the light mass of hydrogen, it is recognized that quantum effects are often important to its reactivity. However, understanding how quantum effects impact the reactivity of hydrogen is still in its infancy. Here, we examine this issue using a well-defined Pd/Cu(111) alloy that allows the activation of hydrogen and deuterium molecules to be examined at individual Pd atom surface sites over a wide range of temperatures. Experiments comparing the uptake of hydrogen and deuterium as a function of temperature reveal completely different behavior of the two species. The rate of hydrogen activation increases at lower sample temperature, whereas deuterium activation slows as the temperature is lowered. Density functional theory simulations in which quantum nuclear effects are accounted for reveal that tunneling through the dissociation barrier is prevalent for H2 up to ∼190 K and for D2 up to ∼140 K. Kinetic Monte Carlo simulations indicate that the effective barrier to H2 dissociation is so low that hydrogen uptake on the surface is limited merely by thermodynamics, whereas the D2 dissociation process is controlled by kinetics. These data illustrate the complexity and inherent quantum nature of this ubiquitous and seemingly simple chemical process. Examining these effects in other systems with a similar range of approaches may uncover temperature regimes where quantum effects can be harnessed, yielding greater control of bond-breaking processes at surfaces and uncovering useful chemistries such as selective bond activation or isotope separation.

Quantum tunneling enabled self-assembly of hydrogen atoms on Cu(111).

Atomic and molecular self-assembly are key phenomena that underpin many important technologies. Typically, thermally enabled diffusion allows a system to sample many areas of configurational space, and ordered assemblies evolve that optimize interactions between species. Herein we describe a system in which the diffusion is quantum tunneling in nature and report the self-assembly of H atoms on a Cu(111) surface into complex arrays based on local clustering followed by larger scale islanding of these clusters. By scanning tunneling microscope tip-induced scrambling of H atom assemblies, we are able to watch the atomic scale details of H atom self-assembly in real time. The ordered arrangements we observe are complex and very different from those formed by H on other metals that occur in much simpler geometries. We contrast the diffusion and assembly of H with D, which has a much slower tunneling rate and is not able to form the large islands observed with H over equivalent time scales. Using density functional theory, we examine the interaction of H atoms on Cu(111) by calculating the differential binding energy as a function of H coverage. At the temperature of the experiments (5 K), H(D) diffusion by quantum tunneling dominates. The quantum-tunneling-enabled H and D diffusion is studied using a semiclassically corrected transition state theory coupled with density functional theory. This system constitutes the first example of quantum-tunneling-enabled self-assembly, while simultaneously demonstrating the complex ordering of H on Cu(111), a catalytically relevant surface.

Impact of hepatitis B vaccination among children in Guangdong Province, China.

OBJECTIVE: To evaluate the impact of the universal infant hepatitis B vaccination program on hepatitis B virus (HBV) infection in Guangdong Province, China. METHODS: In 2006, a serosurvey was conducted in Guangdong Province among children aged <15 years, 14 years after the introduction of universal infant hepatitis B vaccination. The participants were selected by stratified, multi-stage random sampling. Demographic characteristics and hepatitis B vaccination history were collected by a questionnaire and a review of the vaccination records, and serum specimens were tested for hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc), and antibody to hepatitis B surface antigen (anti-HBs) by ELISA. The prevalence rate of HBV serological markers and the rate of immunization coverage in this survey were compared with those of the 1992 and 2002 surveys. RESULTS: A total of 1967 children aged <15 years participated in 2006. The prevalence rate of HBsAg decreased from 19.86% in the 1992 survey to 4.91% in the 2006 survey. The rates of three-dose and timely birth dose coverage of hepatitis B vaccine were 92.40% and 70.84%, respectively, among children born during the period 2002-2005. The prevalence of HBsAg was significantly lower among fully immunized children (1.99%) than among unvaccinated children (5.56%). CONCLUSIONS: Guangdong Province has successfully integrated the hepatitis B vaccine into routine immunization programs and this has had a very significant impact on decreasing the HBsAg carrier rate among children.

Water-mediated proton hopping on an iron oxide surface.

The diffusion of hydrogen atoms across solid oxide surfaces is often assumed to be accelerated by the presence of water molecules. Here we present a high-resolution, high-speed scanning tunneling microscopy (STM) study of the diffusion of H atoms on an FeO thin film. STM movies directly reveal a water-mediated hydrogen diffusion mechanism on the oxide surface at temperatures between 100 and 300 kelvin. Density functional theory calculations and isotope-exchange experiments confirm the STM observations, and a proton-transfer mechanism that proceeds via an H(3)O(+)-like transition state is revealed. This mechanism differs from that observed previously for rutile TiO(2)(110), where water dissociation is a key step in proton diffusion.

Alkali-stabilized Pt-OHx species catalyze low-temperature water-gas shift reactions.

We report that alkali ions (sodium or potassium) added in small amounts activate platinum adsorbed on alumina or silica for the low-temperature water-gas shift (WGS) reaction (H(2)O + CO → H(2) + CO(2)) used for producing H(2). The alkali ion-associated surface OH groups are activated by CO at low temperatures (~100°C) in the presence of atomically dispersed platinum. Both experimental evidence and density functional theory calculations suggest that a partially oxidized Pt-alkali-O(x)(OH)(y) species is the active site for the low-temperature Pt-catalyzed WGS reaction. These findings are useful for the design of highly active and stable WGS catalysts that contain only trace amounts of a precious metal without the need for a reducible oxide support such as ceria.

Low-temperature CO oxidation on Ni(111) and on a Au/Ni(111) surface alloy.

From an interplay between scanning tunneling microscopy, temperature programmed desorption, X-ray photoelectron spectroscopy, and density functional theory calculations we have studied low-temperature CO oxidation on Au/Ni(111) surface alloys and on Ni(111). We show that an oxide is formed on both the Ni(111) and the Au/Ni(111) surfaces when oxygen is dosed at 100 K, and that CO can be oxidized at 100 K on both of these surfaces in the presence of weakly bound oxygen. We suggest that low-temperature CO oxidation can be rationalized by CO oxidation on O(2)-saturated NiO(111) surfaces, and show that the main effect of Au in the Au/Ni(111) surface alloy is to block the formation of carbonate and thereby increase the low-temperature CO(2) production.

Improving electrocatalysts for O(2) reduction by fine-tuning the Pt-support interaction: Pt monolayer on the surfaces of a Pd(3)Fe(111) single-crystal alloy.

We improved the effectiveness of Pt monolayer electrocatalysts for the oxygen-reduction reaction (ORR) using a novel approach to fine-tuning the Pt monolayer interaction with its support, exemplified by an annealed Pd(3)Fe(111) single-crystal alloy support having a segregated Pd layer. Low-energy ion scattering and low-energy electron diffraction studies revealed that a segregated Pd layer, with the same structure as Pd (111), is formed on the surface of high-temperature-annealed Pd(3)Fe(111). This Pd layer is considerably more active than Pd(111); its ORR kinetics is comparable to that of a Pt(111) surface. The enhanced catalytic activity of the segregated Pd layer compared to that of bulk Pd apparently reflects the modification of Pd surface's electronic properties by underlying Fe. The Pd(3)Fe(111) suffers a large loss in ORR activity when the subsurface Fe is depleted by potential cycling (i.e., repeated excursions to high potentials in acid solutions). The Pd(3)Fe(111) surface is an excellent substrate for a Pt monolayer ORR catalyst, as verified by its enhanced ORR kinetics on PT(ML)/Pd/Pd(3)Fe(111). Our density functional theory studies suggest that the observed enhancement of ORR activity originates mainly from the destabilization of OH binding and the decreased Pt-OH coverage on the Pt/Pd/Pd(3)Fe(111) surface. The activity of Pt(ML)/Pd(111) and Pt(111) is limited by OH removal, whereas the activity of Pt(ML)/Pd/Pd(3)Fe(111) is limited by the O-O bond scission, which places these two surfaces on the two sides of the volcano plot.

Epidemiologic clues to SARS origin in China.

An epidemic of severe acute respiratory syndrome (SARS) began in Foshan municipality, Guangdong Province, China, in November 2002. We studied SARS case reports through April 30, 2003, including data from case investigations and a case series analysis of index cases. A total of 1,454 clinically confirmed cases (and 55 deaths) occurred; the epidemic peak was in the first week of February 2003. Healthcare workers accounted for 24% of cases. Clinical signs and symptoms differed between children (<18 years) and older persons (> or =65 years). Several observations support the hypothesis of a wild animal origin for SARS. Cases apparently occurred independently in at least five different municipalities; early case-patients were more likely than later patients to report living near a produce market (odds ratio undefined; lower 95% confidence interval 2.39) but not near a farm; and 9 (39%) of 23 early patients, including 6 who lived or worked in Foshan, were food handlers with probable animal contact.

[Effectiveness of personal protective measures in prevention of nosocomial transmission of severe acute respiratory syndrome].

OBJECTIVE: To evaluate the effectiveness of personal protective measures of health care workers (HCWs) against severe acute respiratory syndrome (SARS). METHODS: A case-control study from ten hospitals in Guangdong, with 180 non-infected and 77 infected staff members that accessed the isolation unit every day, and participated in direct first aid for severe SARS patients. All participants were surveyed about how they were using personal protective equipment (PPE), protective drugs and hygiene habits when caring for patients with SARS. Statistical analysis was done with either chi(2) or Fisher's exact test for univariate analysis, whereas we used forward stepwise selection (Waldesian) for logistic regression. RESULTS: Univariate analysis showed that mask, gown, gloves, goggles, footwear, "hand-washing and disinfecting", gargle, "membrane protection", "taking shower and changing clothing after work", "avoid from eating and drinking in ward", oseltamivir phospha tall had protective effects (P < 0.05), but stepwise logistic regression showed significant differences for mask (OR = 0.78, 95% CI: 0.60 - 0.99), goggles (OR = 0.20, 95% CI: 0.10 - 0.41) and footwear (OR = 0.58, 95% CI: 0.39 - 0.86). Analysis for linear trend in proportions showed that dose response relationship existed in mask, gown, gloves, goggles, footwear, gargle, "membrane protection" and "taking shower and changing dree after work" (P < 0.01). The attack rate of HCWs who were rescuing severe SARS patients without any PPE was 61.5% (16/26). It seemed that the more the protective measures were used, the higher the protective effect was (P < 0.001), and could reach 100% if mask, gown, gloves, goggles, footwear, "hand-washing and disinfecting" were all used at the same time. CONCLUSIONS: Nosocomial infection of SARS can be prevented effectively by precautions against droplets and personal contact. HCWs must take strict protection according to the guidance of WHO or Chinese MOH and pay attention to personal hygiene.