Tungsten-based nanocatalysts with different structures for visible light responsive photocatalytic degradation of bisphenol A

Environmental pollution, such as water contamination, is a critical issue that must be absolutely addressed. Here, three different morphologies of tungsten-based photocatalysts (WO3 nanorods, WO3/WS2 nanobricks, WO3/WS2 nanorods) are made using a simple hydrothermal method by changing the solvents (H2O, DMF, aqueous HCl solution). The as-prepared nanocatalysts have excellent thermal stability, large porosity, and high hydrophilicity. The results show all materials have good photocatalytic activity in aqueous media, with WO3/WS2 nanorods (NRs) having the best activity in the photodegradation of bisphenol A (BPA) under visible-light irradiation. This may originate from increased migration of charge carriers and effective prevention of electron‒hole recombination in WO3/WS2 NRs, whereby this photocatalyst is able to generate more reactive •OH and •O2- species, leading to greater photocatalytic activity. About 99.6% of BPA is photodegraded within 60 min when using 1.5 g/L WO3/WS2 NRs and 5.0 mg/L BPA at pH 7.0. Additionally, the optimal conditions (pH, catalyst dosage, initial BPA concentration) for WO3/WS2 NRs are also elaborately investigated. These rod-like heterostructures are expressed as potential catalysts with excellent photostability, efficient reusability, and highly active effectivity in different types of water. In particular, the removal efficiency of BPA by WO3/WS2 NRs reduces by only 1.5% after five recycling runs and even reaches 89.1% in contaminated lake water. This study provides promising insights for the nearly complete removal of BPA from wastewater or different water resources, which is advantageous to various applications in environmental remediation.

Mapping potential conflicts between global agriculture and terrestrial conservation

Demand for food products, often from international trade, has brought agricultural land use into direct competition with biodiversity. Where these potential conflicts occur and which consumers are responsible is poorly understood. By combining conservation priority (CP) maps with agricultural trade data, we estimate current potential conservation risk hotspots driven by 197 countries across 48 agricultural products. Globally, a third of agricultural production occurs in sites of high CP (CP > 0.75, max = 1.0). While cattle, maize, rice, and soybean pose the greatest threat to very high-CP sites, other low-conservation risk products (e.g., sugar beet, pearl millet, and sunflower) currently are less likely to be grown in sites of agriculture-conservation conflict. Our analysis suggests that a commodity can cause dissimilar conservation threats in different production regions. Accordingly, some of the conservation risks posed by different countries depend on their demand and sourcing patterns of agricultural commodities. Our spatial analyses identify potential hotspots of competition between agriculture and high-conservation value sites (i.e., 0.5° resolution, or ~367 to 3,077km², grid cells containing both agriculture and high-biodiversity priority habitat), thereby providing additional information that could help prioritize conservation activities and safeguard biodiversity in individual countries and globally. A web-based GIS tool at https://agriculture.spatialfootprint.com/biodiversity/ systematically visualizes the results of our analyses.

Kinetic study on methylene blue removal from aqueous solution using UV/chlorine process and its combination with other advanced oxidation processes

This study investigated the kinetic degradation of methylene blue (MB) by a UV/chlorine process and its combination with other advanced oxidation processes. The ∙OH and reactive chlorine species (RCS: Cl∙, ClO∙, etc.) were the primary reactive species, which accounted for 56.7% and 37.6% of MB degradation at pH 7, respectively. The second-order rate constant of Cl∙ towards MB was calculated to be 2.8 × 10⁹ M^-1 s^-1. When the pH increased from 3 to 7, k_MB by ∙OH increased from 0.15 to 0.21 min^-1 before being reduced to 0.11 min^-1 at pH 11. k_MB by RCS continuously reduced from 0.16 to 0.13 min^-1 when the pH was increased to 11. Humic acid (HA), Br^-, and Cl^- inhibited the degradation with k_MB in the order: k_MB (in HA) < k_MB (in Br^-) < k_MB (in Cl^-). HCO₃^- increased k_MB from 0.37 to 0.48 min^-1. The experimental and modeling methods fit well, indicating the effectiveness of using Kintecus® in predicting concentrations of free radicals in complex water matrices. TOC removal was achieved at 60% after 30 min in a control process and it was strongly inhibited by the presence of HA, with 22% removal achieved at 5 mg_c L^-1 HA. UV/chlorine/electrochemical oxidation (UV/chlorine/EO) significantly improves k_MB from 0.37 to 0.94 min^-1 at a high current (240 mA), while UV/chlorine/H₂O₂ decreased k_MB at a low concentration of 0.01 mM H₂O₂ (k_MB decreased by 6.1%). The results indicate that the energy cost for UV irradiation was the main cost in MB treatment in both UV/chlorine and UV/persulfate (UV/PS) processes, accounting for 91% and 84%, respectively.

Degradation of dyes by UV/Persulfate and comparison with other UV-based advanced oxidation processes: Kinetics and role of radicals

This study investigated the degradation of methylene blue (MeB), methyl orange (MeO), and rhodamin B (RhB) by the UV/Persulfate (UV/PS) process. The dye degradation in the investigated UV-based Advanced Oxidation Processes (UV/AOPs) followed the first-order kinetic model. The second-order rate constant of the dyes with •OH, SO₄^•-, and CO₃^•- were calculated and found to be: k_•OH,MeB = 5.6 × 10⁹ M^-1 s^-1, [Formula: see text]  = 3.3 × 10⁹ M^-1 s^-1, [Formula: see text]  = 6.9 × 10⁷ M^-1 s^-1; k_•OH,MeO = 3.2 × 10⁹ M^-1 s^-1, [Formula: see text]  = 13 × 10⁹ M^-1 s^-1, [Formula: see text]  = 4.4 × 10⁶ M^-1 s^-1; k_•OH,RhB = 14.8 × 10⁹ M^-1 s^-1, [Formula: see text]  = 5 × 10⁹ M^-1 s^-1, [Formula: see text]  = 1 × 10⁷ M^-1 s^-1. The steady-state concentrations of •OH and SO₄^•- (including other reactive species) were determined using both chemical probes and modeling methods (Kintecus® V6.8). In the UV/PS, the dye degradation depends on the pH of the solution with the order: k_dye (at pH of 7) > k_dye (in acidic conditions) > k_dye (in alkaline conditions). The presence of water matrices had different impacts on dye degradation: 1) The HCO₃^- and Cl^- promoted the degradation efficiency of one dye, but also inhibited the degradation of other dyes; 2) Humic acid (HA) inhibited dye degradation as it scavenged both •OH and SO₄^•-. The degradation of the dyes by UV/PS was also compared with the UV/Chlorine (UV/HOCl) and UV/H₂O₂ and it was established that: 1) In UV/PS and UV/HOCl, SO₄^•- and RCS contributed to dye degradation more than •OH, while •OH played a major role in dye degradation by UV/H₂O₂; 2) The calculated toxicity in UV/PS was the lowest probably due to the low toxicity of by-products; 3) For MeO and RhB, the UV/PS process is more beneficial for the total organic carbon (TOC) removal compared to that of the UV/HOCl and UV/H₂O₂ processes; 4) The UV/PS showed lower cost than the UV/HOCl and UV/H₂O₂ systems for MeO, and RhB degradation but higher cost for MeB removal.

Electrochemical preparation of monodisperse Pt nanoparticles on a grafted 4-aminothiophenol supporting layer for improving the MOR reaction

The methanol oxidation reaction (MOR) has recently gained a lot of attention due to its application in fuel cells and electrochemical sensors. To enhance the MOR, noble metal nanoparticles should be homogeneously dispersed on the electrode surface with the aid of one suitable support. In this work, 4-aminothiophenol (4-ATP) molecules which contain simultaneously amine and thiol groups were electro-grafted onto the electrode surface to provide anchoring sites, limit aggregation and ensure good dispersion of metal nanoparticles. The results showed a high density of platinum nanoparticles (PtNPs) with an average size of 25 nm on the glassy electrode modified with a 4-ATP supporting layer. Consequently, the MOR was improved by 2.1 times with the aid of the grafted 4-ATP layer. The electrochemical sensor based on PtNPs/4-ATP/GCE is able to detect MeOH in a linear range from 1.26 to 21.42 mM with a detection limit of 1.21 mM.

Well-dispersed Pt nanoparticles for MOR reaction.

An Electrochemical Sensor Based on Gold Nanodendrite/Surfactant Modified Electrode for Bisphenol A Detection

In the present work, we reported the simple way to fabricate an electrochemical sensing platform to detect Bisphenol A (BPA) using galvanostatic deposition of Au on a glassy carbon electrode covered by cetyltrimethylammonium bromide (CTAB). This material (CTAB) enhances the sensitivity of electrochemical sensors with respect to the detection of BPA. The electrochemical response of the modified GCE to BPA was investigated by cyclic voltammetry and differential pulse voltammetry. The results displayed a low detection limit (22 nm) and a linear range from 0.025 to 10 µm along side with high reproducibility (RSD = 4.9% for seven independent sensors). Importantly, the prepared sensors were selective enough against interferences with other pollutants in the same electrochemical window. Notably, the presented sensors have already proven their ability in detecting BPA in real plastic water drinking bottle samples with high accuracy (recovery range = 96.60%-102.82%) and it is in good agreement with fluorescence measurements.

Effects of nutrient supply and nutrient ratio on diversity-productivity relationships of phytoplankton in the Cau Hai lagoon, Vietnam

Diversity and productivity of primary producers are known to be influenced simultaneously by resource availability and resource ratio, but the relative importance of these two factors differed among studies and so far only entire phytoplankton communities were investigated which might ignore specific nutrient requirements and stoichiometric plasticity of different functional groups. We measured nutrient availability (DIN, total N [TN], total P [TP]), nutrient imbalance (TN:TP, DIN:TP, N:Pseston), species richness, and abundance of the whole phytoplankton community, as well as those specific for cyanobacteria, diatoms, and dinoflagellates in Cau Hai lagoon in Vietnam. We determined the correlation among these variables, using structural equation modeling. The models applied to the whole phytoplankton community indicated that the nutrient availability (particularly TP and DIN) drove variation in phytoplankton abundance and richness, and that abundance also depended on species richness. The models applied to different functional groups differed considerably from the entire community and among each other, and only a part of the models was significant. The relationship between nutrient availability (mainly TP) and abundance was driven by cyanobacteria, and the relationship between nutrient imbalance (only with N:Pseston) and species richness was driven by diatoms. Remarkably, the positive relationship between species richness and abundance, as consistently observed for the whole phytoplankton community, was only observed for one of the three functional groups (diatoms), indicating that resource complementarity occurs particularly among species of different functional groups. Our results emphasized that nutrient availability (TP and to a lesser extent DIN) as well as nutrient imbalance (albeit only with N:Pseston as proxy) were driving factors for the phytoplankton community in the Cau Hai lagoon and hence alterations in both of these factors leading to a shift in phytoplankton species composition and productivity.

Hand Replantations Following Complete Amputations at the Wrist Joint: First Experiences in Hanoi, Vietnam

Five completely amputated hands at the level of the wrist joint were replanted. The five patients were all men, ranging from 19 to 31 years and the amputations were all the result of knife injuries. All the revascularizations were successful. Secondary tenolysis was required in one case. Postoperative functional results compared to the uninjured hand were evaluated according to five main criteria: (1) the patient’s overall satisfaction with the hand; (2) recovery of flexor and extensor function of the thumb and fingers; (3) recovery of thumb opposition; (4) recovery of sensitivity in the median and ulnar nerve distributions; (5) ability of the surviving hand to perform daily tasks. The results showed that, although the replanted hands were never functionally as good as the contralateral hand, the patients were able to use them satisfactorily for activities of daily living. Our results demonstrate that replantation following complete amputation at the wrist joint level as a result of a sharp injury is extremely worthwhile and has excellent potential for functional recovery.

[Microsurgical thumb replantation following traumatic amputation: preliminary results in Hanoi, Vietnam]

INTRODUCTION

Replantation using microsurgical techniques is a fairly new procedure in Vietnam. We reviewed and evaluated our 7-year results of thumb replantation in Vietnamese patients following traumatic thumb amputation.

MATERIAL AND METHODS

Traumatic thumb amputations between September 1999 and July 2006 were reexamined and evaluated. Postoperative functional results were evaluated based on four main criteria: 1) the patient's subjective attitude regarding the replanted thumb, 2) the degree of mobility of the replanted thumb compared with its counterpart, 3) the level of sensitivity of the replanted thumb, and 4) the objective ability to perform daily tasks.

RESULTS

A total of 26 patients were documented. The duration of follow-up averaged 22 months (range 6-72 months). The success rate of replantation was 81%. A rating of either "good" or "very good" was obtained for 81% of the replanted thumbs.

DISCUSSION

Vascular thrombosis was the cause of all failures. Proper debridement, standardized microvascular techniques, timely detection of thrombosis formation, and reoperation using vein grafts play a decisive role in the final success.

Comparison of experimental microvascular end-to-end anastomosis via VCS-Clips versus conventional suture technique in an animal model

In this experimental study on 96 CD rats, microvascular end-to-end anastomoses created via suture or alternatively by means of a VCS-Clip-Application-System, were compared. The aorta abdominalis of the animals, with a diameter of 1.5 +/- 0.2 mm, was experimentally dissected, and the free ends of the vessel then anastomosed. The results were evaluated using sonography, microangiography, histologic examination, and vascular imprints. Postoperative examination was carried out after 1, 3, 7, 14, or 30 days. Major advantages of the VCS-Clip technique over suturing were that it was easy to learn, significantly faster to perform (execution of anastomosis 10.9 +/- 2.6 min versus 19.4 +/- 5.0 min), and produced significantly more favorable histologic results in terms of less inflammatory response, foreign body reaction, necrosis of the tunica media, hyperplasia of the intima, and thrombosis of the vessel lumen. The main disadvantage of the clip technique was a significantly higher rate of stenoses (15.8 +/- 6.0 versus 4.1 +/- 6.6 percent).