Design and Computational Validation of γ-Ray Shielding Effectiveness in Heavy Metal/Rare Earth Oxide-Natural Rubber Composites.

This study involved the preparation of natural rubber-based composites incorporating varying proportions of heavy metals and rare earth oxides (Sm2O3, Ta2O5, and Bi2O3). The investigation analyzed several parameters of the samples, including mass attenuation coefficients (general, photoelectric absorption, and scattering), linear attenuation coefficients (µ), half-value layers (HVLs), tenth-value layers (TVLs), mean free paths (MFPs), and radiation protection efficiencies (RPEs), utilizing the Monte Carlo simulation software Geant4 and the WinXCom database across a gamma-ray energy spectrum of 40-150 keV. The study also compared the computational discrepancies among these measurements. Compared to rubber composites doped with single-component fillers, multi-component mixed shielding materials significantly mitigate the shielding deficiencies observed with single-component materials, thereby broadening the γ-ray energy spectrum for which the composites provide effective shielding. Subsequently, the simulation outcomes were juxtaposed with experimental data derived from a 133Ba (80 keV) γ-source. The findings reveal that the simulated results align closely with the experimental observations. When compared to the WinXCom database, the Geant4 software demonstrates superior accuracy in deriving radiation shielding parameters and notably enhances experimental efficiency.

An oxygen vacancy-rich BiO2-x/COF heterojunction for photocatalytic degradation of diclofenac.

A BiO2-x/COF composite was successfully synthesized by simple mechanical ball milling. Compared to pure BiO2-x and COFs, the BiO2-x/COF composite (1 : 9) showed superior photocatalytic capability. Under visible light irradiation for 90 min, the photocatalytic degradation rate of DCF reached 97%. In addition, the characterization results showed that the formation of heterojunctions and the increase in oxygen vacancy concentration were the reasons for the enhancement of the photocatalytic activity. It is confirmed by free radical capture experiments that ˙O2- and h+ are the main reactive substances in the photocatalytic process. The photocatalytic degradation mechanism of the composite and the photocatalytic degradation pathway of diclofenac were deduced.

WO3/MIL-125 (Ti) composite material for enhancing the reduction of Cr(vi) under visible light.

In wastewater containing heavy metals, Cr(vi) is a potentially toxic metal, mainly derived from production and processing processes such as textile printing, dyeing, ore mining, battery applications, metal cleaning and electroplating. WO3 is widely used in photocatalytic degradation and reduction, and its utilization rate of visible light is high. However, the rapid recombination of photogenerated electron-hole pairs of WO3 limits its use. In this work, the composite material (WxMy) of WO3 and MIL-125 (Ti) was prepared by the ball milling method, and the catalyst was used to photocatalytically reduce Cr(vi). After using W90M10 as a photocatalyst for 50 min, the reduction rate of Cr(vi) can reach 99.2%, and the reduction rate is 2.3 times that of WO3. After 5 cycles of use, the reduction rate can still reach 91.3%. It is mainly due to the formation of a II-type heterojunction between WO3 and MIL-125 (Ti), which promotes the separation of photogenerated electron-hole pairs, thus improving the efficiency of photocatalytic reduction of Cr(vi).

Ligand-Induced Synthesis of Highly Stable NM88(DB)@COF-JLU19 Composite: Accelerating Electron Flow for Visible-Light-Efficient Degradation of Tetracycline Hydrochloride.

In recent years, the response of new porous materials to visible light and their potential applications in wastewater treatment has received extensive attention from the scientific community. Metal Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs) have been the focus of attention due to their strong visible light absorption, high specific surface area, well-regulated pore structures, and diverse topologies. In this study, a novel MOF@COF composite with a high surface area, high crystallinity, and structural stability was obtained using the covalent bond formation strategy from COF-JLU19 and NH2-MIL-88B(Fe). Under visible light irradiation, the degradation of tetracycline hydrochloride by this material reached more than 90% within 10 min and was completely degraded within 30 min, which exceeded the degradation rate of individual materials. Remarkably, the catalytic activity decreased by less than 5% even after five degradation cycles, indicating good structural stability. The excellent photocatalytic performance of the NM88(DB)@COF-JLU19 hybrids was attributed to the formation of covalent bonds, which formed a non-homogeneous interface that facilitated effective charge separation and promoted the generation of hydroxyl radicals.

Simultaneous measurement of 19 steroid hormones in dried blood spots using ultra-performance liquid chromatography-tandem mass spectrometry.

A rapid and accurate ultra-performance liquid chromatography-tandem-mass spectrometry (UPLC-MS/MS) method was developed for the measurement of 19 steroid hormones in dried blood spots and to achieve the highly traceable analysis of steroid hormones in dried blood samples. In this method, a BEH C8 column and UPLC-MS/MS were used for the separation of the steroid hormones. The extraction process was simple and accurate. The distribution ranges of 19 steroid hormones in four healthy individuals (2 males and 2 females) were determined simultaneously by positive ionization mode (ESI+) and negative ionization mode (ESI-) analysis, which were recorded by multiple reaction monitoring (MRM) modes. The linearity of the standard curves of 19 steroid hormones in dried blood spots was good, and the linear correlation coefficients R2 were all ≥0.997. Meanwhile, the matrix effect of the method ranged from 87.1% to 131.3%. Across the analytical range, the inter-assay coefficient of variation (CV) was <12.07% and the intra-assay CV was <18.16%. The spiked recovery was >67.33%. The distribution ranges of 19 steroid hormones in four healthy individuals were in agreement with those in previous reports. A UPLC-MS/MS method for the simultaneous measurement of 19 steroid hormones in dried blood spots was developed to achieve traceable analysis of steroid hormones in dried blood samples.

Enhanced photocatalytic activity of TiO2/UiO-67 under visible-light for aflatoxin B1 degradation.

TiO2 has great potential in photocatalytic degradation of organic pollutants, but poor visible light response and low separation efficiency of photogenerated electron-hole pairs limit its wide applications. In this study, we have successfully prepared TiO2/UiO-67 photocatalyst through an in situ solvothermal method. The degradation rate of aflatoxin B1 (AFB1) is 98.9% in only 80 min, which is superior to the commercial P25, commercial TiO2 and most of reported photocatalysts under visible light irradiation. In addition, the TiO2/UiO-67 photocatalyst showed excellent recyclability. We demonstrated that the enhanced photocatalytic mechanism was owing to the heterojunction between TiO2 and UiO-67, which enhanced effectively the separation photogenerated charge carriers and visible light response. The free radical trapping tests demonstrated that superoxide radicals (˙O2 -), holes (h+) and hydroxyl radicals (˙OH) were the main active species and then oxidized AFB1 to some small molecules.

Nickel Coated Polyester Sponge for Delaying the Specific Aggregation of Fine Particles Induced by Negative Air Ions.

Negative air ions (NAIs) produced by corona discharge is often used for indoor air purification; however, the specific aggregation of suspended particles caused by NAIs, especially fine particles (FPs), needs to be considered. Here, a nickel coated conductive sponge (NCCS) was used as the main adsorption interface for delaying the obstinate aggregation caused by NAIs on another surface. The specific aggregation of FPs is caused by the directional transfer of electric charge, and the oxidation characteristic of NAIs results in the surface reaction of FPs simultaneously. The conductivity and roughness of the adsorption interface determine the migration direction and enrichment number of FPs, respectively. Nickel coated conductive sponge with high conductivity and high specific surface area can effectively adsorb the FPs affected by NAIs and can effectively delay the specific aggregation on the surface of indoor objects.

In Vivo Kinetics and Biotransformation of Aflatoxin B1 in Dairy Cows Based on the Establishment of a Reliable UHPLC-MS/MS Method.

The in vivo kinetics of aflatoxin B1 (AFB1) and its carry-over as aflatoxin M1 (AFM1) in milk as well as the toxin loads in the tissue of dairy cows were assessed through a repetitive feeding trial of an AFB1-contaminated diet of 4 µg kg-1 body weight (b.w.) for 13 days. This was followed by a clearance period that ended with a single dose trial of an AFB1-contaminated diet of 40 µg kg-1 b.w. An ultra-high performance liquid chromatography tandem mass spectrometry method was developed and successfully validated by the determination of linearity (R 2 ≥ 0.990), sensitivity (lower limit of quantification, 0.1-0.2 ng ml-1), recovery (79.5-111.2%), and precision relative standard deviation (RSD) ≤14.7%) in plasma, milk, and various tissues. The repetitive ingestion of AFB1 indicated that the biotransformation of AFB1 to AFM1 occurred within 48 h, and the clearance period of AFM1 in milk was not more than 2 days. The carry-over rate of AFM1 in milk during the continuous ingestion experiment was in the range of 1.15-2.30% at a steady state. The in vivo kinetic results indicated that AFB1 reached a maximum concentration of 3.8 ± 0.9 ng ml-1 within 35.0 ± 10.2 min and was slowly eliminated from the plasma, with a half-life time (T1/2) of 931.1 ± 30.8 min. Meanwhile, AFM1 reached a plateau in plasma (0.5 ± 0.1 ng ml-1) at 4 h after the ingestion. AFB1 was found in the heart, spleen, lungs, and kidneys at concentrations of 1.6 ± 0.3, 4.1 ± 1.2, 3.3 ± 0.9 and 5.6 ± 1.4 µg kg-1, respectively. AFM1 was observed in the spleen and kidneys at concentrations of only 0.7 ± 0.2 and 0.8 ± 0.1 µg kg-1, respectively. In conclusion, the in vivo kinetics and biotransformation of AFB1 in dairy cows were determined using the developed UHPLC-MS/MS method, and the present findings could be helpful in assessing the health risks to consumers.

Inhibition Effect of Negative Air Ions on Adsorption between Volatile Organic Compounds and Environmental Particulate Matter.

This work focused on the chemisorption of volatile organic compounds (VOCs) on particulate matter of less than 2.5 µm (PM2.5). The detection results illustrated that VOCs on PM2.5 containing hydroxyl, carbonyl, and ester groups and CxHy on PM2.5 were sequentially decreased as 70.02, 21.35, 6.42, and 2.21%, respectively. The chemisorption mechanism showed that the stronger the electronegativity of oxygen-containing functional groups of VOCs, the easier it is to adsorb them on the silicate PM2.5 due to hydrogen bond formation. Strong electronegative oxygen-containing functional groups readily interacted through hydrogen bonds with silanol groups, which was the main component of PM2.5, resulting in VOC adsorption on PM2.5. Negative air ions (NAIs) can weaken the offset ability of the lone pair of electrons in oxygen-containing functional groups in VOCs, which could significantly weaken the possibility of forming hydrogen bonds with silanol groups. Therefore, NAIs can effectively inhibit the adsorption between VOCs and PM2.5, leading to a significant reduction in VOCs on the surface of PM2.5.

Controllable Synthesis of Multicompartmental Particles Using 3D Microfluidics.

A microfluidic assembly method based on a microfluidic chip and capillary device was developed to create multicompartmental particles. The microfluidic chip design endows the particles with regulable internal structure. By adjusting the microstructure of the chip, the diameter of the capillary, the gap length between the two microfluidic components, and the flow rates, the size of the particles and the number or the ratio of different regions within the particle could be widely varied. As a proof of concept, we have produced some complicated particles that even contain 20 compartments. Furthermore, the potential applications of the anisotropic particles are explored by encapsulating magnetic beads, fluorescent nanoparticles, and the cells into different compartments of the microparticles. We believe that this method will open new avenues for the design and application of multicompartmental particles.

Highly efficient hamburger-like nanostructure of a triadic Ag/Co3O4/BiVO4 photoanode for enhanced photoelectrochemical water oxidation.

The combination of a semiconductor heterojunction and oxygen evolution cocatalyst (OEC) is an important strategy to improve photoelectrochemical (PEC) water oxidation. Herein, a novel hamburger-like nanostructure of a triadic photoanode composed of BiVO4 nanobulks, Co3O4 nanosheets and Ag nanoparticles (NPs), that is, Ag/Co3O4/BiVO4, was designed. In our study, an interlaced 2D ultrathin p-type Co3O4 OEC layer was introduced onto n-type BiVO4 to form a p-n Co3O4/BiVO4 heterojunction with an internal electric field (IEF) in order to facilitate charge transport. Then the modification with Ag NPs can significantly facilitate the separation and transport of photogenerated carriers through the surface plasma resonance (SPR) effect, inhibiting the electron-hole recombination. The resulting Ag/Co3O4/BiVO4 photoanodes exhibit largely enhanced PEC water oxidation performance: the photocurrent density of the ternary photoanode reaches up to 1.84 mA cm-2 at 1.23 V vs. RHE, which is 4.60 times higher than that of the pristine BiVO4 photoanode. The IPCE value is 2.83 times higher than that of the pristine BiVO4 at 400 nm and the onset potential has a significant cathodic shift of 550 mV for the ternary well-constructed photoanode.

Enhanced active oxidative species generation over Fe-doped defective TiO2 nanosheets for boosted photodegradation.

Semiconductor photocatalysis is widely proposed for decomposing multiple pollutants via photo-generated oxidative species. However, the photocatalytic degradation performance in practical settings still remains unsatisfactory due to the limited production of active oxidative species (AOS). In this work, a defect engineering strategy was developed to explore the superiority of oxygen vacancies (Vo) and their structural regulation to enhance AOS production for boosting photodegradation. Taking anatase TiO2 as a model photocatalyst, ultrathin TiO2 nanosheets containing abundant Vo and appropriate Fe doping exhibited an unprecedented 134 times higher activity in the degradation of Rhodamine B (RhB) (rate as high as 0.3073 min-1) than bulk anatase and were superior to most reported photocatalysts. The defect-rich ultrathin TiO2 nanosheets could be further applied in high-efficiency degradation of tetracycline hydrochloride (TC-HCl) with the degradation rate of 0.0423 min-1. The in situ electron paramagnetic resonance, advanced spectroscopic characterization and electrochemical measurement revealed the key role of Vo and Fe doping in facilitating the production of photo-generated holes and superoxide radicals (˙O2 -) that were identified to be effective to decompose both RhB and TC-HCl. This research provides insight into defect engineering promoting AOS generation and gives inspiration for the design of efficient photocatalysts for photooxidation applications.

Hydrated negative air ions generated by air-water collision with TiO2 photocatalytic materials.

Photocatalytic materials are often used in the field of electrolysis of water for its competitive performance and low cost. This study describes the use of TiO2 for providing free electrons to prepare hydrated negative air ions together with the Lenard effect caused by air-water collision. The lifetime of HNAIs increased by 47.62% in comparison with the traditional corona discharge method; both the stability and the actual yield of the HNAIs increased significantly. The stability of HNAIs has a correlative relationship with the molecular weight and relative humidity. Lower mobility of the HNAIs with larger molecular weight results in low probability of collision with other air particles, making it relatively stable. Water molecules could form a water shell around the cluster ions in a high relative humidity environment, which can protect the ions, avoiding physical collision to extend the lifetime.

A novel homolateral and dicationic AIEgen for the sensitive detection of casein.

The exploitation of highly soluble and responsive AIEgens is essential for further expansion of their practical applications. In this study, dipropyltrimethylammonium bromide-substituted TPE (denoted as o-TPEDTA), a homolateral and dicationic AIEgen, was synthesized and applied for the turn-on detection of casein via hydrophobic interactions. The rapid and sensitive detection of casein was achieved using the designed o-TPEDTA probe with the limit of detection of 0.05 µg mL-1. The satisfying selectivity of over 1000-fold concentration of other probably existing chemicals, including amino acids, sugars and salts, was achieved due to the strong binding affinity between o-TPEDTA and casein. The evaluation of casein in milk powder samples with small relative standard deviations was realized using the o-TPEDTA probe. The accuracy of the o-TPEDTA probe-based detection method was validated by the consistency of the casein detection results with those obtained via a national standard casein evaluation approach.

Efficient bacteria inactivation by ligand-induced continuous generation of hydroxyl radicals in Fenton-like reaction.

Fenton/Fenton-like reaction is often used as an efficient method to generate hydroxyl radicals (HO) for bacteria inactivation in aqueous solution. However, inactivation efficiency of bacteria in aqueous solution using Fenton/Fenton-like reactions needs to further improve as a result of transient generation of HO. In this paper, we found that the formation of Tris-Co(II) complexes could decrease the redox potential of Co(III)/Co(II), facilitating the transformation of Tris-Co(III) complexes into Tris-Co(II) complexes. Therefore, HO could be generated continuously in the presence of H2O2. Especially, Tris-Co(II) complexes are apt to combine with Escherichia Coli cells by electrostatic interactions, inducing a higher utilization ratio of the generated HO. Therefore, the proposed Tris-Co(II) complex-H2O2 system could be employed as a high-efficiency sterilizing reagent for inactivation of E. Coli. This work provides a promising strategy for bacterial inactivation via an economic and eco-friendly manner.

Tris-Co(II)-H2O2 System-Mediated Durative Hydroxyl Radical Generation for Efficient Anionic Azo Dye Degradation by Integrating Electrostatic Attraction.

The development of simple Fenton/Fenton-like systems with durative hydroxyl radical (•OH) generation characteristics is significant to rapid organic pollutant degradation and cost-effective water treatment. In this study, a tris(hydroxymethyl)aminomethane (Tris)-incorporated Co(II)-H2O2 Fenton-like system has been successfully constructed for efficient Sunset Yellow (SY, a typical anionic azo dye) degradation under alkaline conditions. The mechanism of the enhanced degradation consists of two parts: first, the Tris-Co(II) complex triggers the durative generation of highly oxidized hydroxyl radicals; second, electrostatic attraction between SY and the Tris-Co(II) complex shortens the radical-SY interaction time and facilitates the degradation of SY. With the introduction of Tris to this proposed system, the decolorization rate of SY can be increased from 37.0 to 98.0% after 50 min and efficient SY degradation with a high total organic carbon removal efficiency (>59.0%) is achieved under a wide initial pH from 8.7 to 12.0. Moreover, the universality of the designed system for anionic azo dye degradation is verified with reactive red and congo red.

DNA-Mediated rolling circle amplification for ultrasensitive detection of thrombin using MALDI-TOF mass spectrometry.

A DNA-mediated rolling circle amplification (RCA) strategy was established for ultrasensitive and specific detection of thrombin via matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). This platform provides a versatile assay for the detection of various biomolecules of low abundance.

Highly efficient degradation of phenol from wastewater via an electro-catalytic oxidation approach with a CeO2-CuO cathode.

The development of highly efficient cathode materials for the electro-catalytic oxidation of phenol from wastewater is of vital importance for environment protection. Herein, we develop an effective CeO2-CuO electrocatalyst for 2-electron oxygen reduction reaction (ORR) to generate H2O2, and then applied it as the cathode for the electro-catalytic oxidation of phenol. Results showed that the CeO2-CuO cathode with different contents of CuO exhibited a higher yield of H2O2 than those of CuO and CeO2, and the highest yield of H2O2 (114 mg L-1) was achieved with a CuO content of 13.4%. The resultant CeO2-CuO-13.4% cathode demonstrated a high degradation rate of 91% after 180 min, which was 1.82-fold and 1.52-fold higher than pure CuO (50%) and CeO2 (60%) electrodes, respectively. Furthermore, the degradation rate of phenol via the electro-catalytic oxidation technology by using a CeO2-CuO cathode significantly outperformed that of the chemical oxidation approach. The outstanding degradation performance of the CeO2-CuO cathode is attributed to the high yield of H2O2 and the strong interaction of CeO2 and CuO.

Microwave-assisted solvothermal synthesis of hierarchical TiO2 microspheres for efficient electro-field-assisted-photocatalytic removal of tributyltin in tannery wastewater.

Organotin compounds have been widely used in recent decades, however, the residential tributyltin (TBT) in environment has potential harmful effects on human health due to the disruption of endocrine system even at trace level. Herein, this work reports on an effective electro-field-assisted-photocatalytic technique for removal of TBT by applying an electric field to photocatalysis of as-prepared hierarchical TiO2 microspheres. The synthesis of catalytic materials is based on a self-assembly process induced by microwave-assisted solvothermal reaction. Hierarchical TiO2 microspheres consisting of nanowires can be obtained in short time with this facile method and possess high surface area and superior optical properties. As the catalyst, it was found that the reaction rate constant of electro-field-assisted-photocatalytic removal (0.0488 min-1) of TBT exhibited almost a 9 fold improvement as compared to that of photocatalysis (0.0052 min-1). The proposed mechanism of electro-field-assisted-photocatalytic removal of TBT was verified by using 117Sn-enriched TBT spike solution as an isotopic tracer. In addition, varying impacts from some key reaction conditions, such as voltage of potential, pH value and the presence of Cr and formaldehyde were also discussed. The overall satisfactory TBT removal performance of the proposed electro-field-assisted-photocatalysis procedure with hierarchical TiO2 microspheres, which was validated using actual tannery wastewater samples from three different kinds of tanning procedures. These attributes suggest that this electro-field-assisted-photocatalysis may have broad applications for the treatment of tannery wastewater.

Improved sensitivity via layered-double-hydroxide-uniformity-dependent chemiluminescence.

In the last two decades nanoparticles have been widely applied to enhance chemiluminescence (CL). The morphology of nanoparticles has an important influence on nanoparticle-amplified CL. However, studies of nanoparticle-amplified CL focus mainly on the size and shape effects, and no attempt has been made to explore the influence of uniformity in nanoparticle-amplified CL processes. In this study we have investigated nanoparticle uniformity in the luminol-H2O2 CL system using layered double hydroxides (LDHs) as a model material. The results demonstrated that the uniformity of LDHs played a key role in CL amplification. A possible mechanism is that LDHs with high uniformity possess abundant catalytic active sites, which results in high CL intensity. Meanwhile, the sensitivity for H2O2 detection was increased by one order of magnitude (1.0 nM). Moreover, the uniform-LDH-amplified luminol CL could be applied to selective detection of glucose in human plasma samples. Furthermore, such a uniformity-dependent CL enhancement effect could adapted to other redox CL systems-for example, the peroxynitrous acid (ONOOH) CL system.