The adsorption and release mechanism of different aged microplastics toward Hg(II) via batch experiment and the deep learning method.

Aged microplastics are ubiquitous in the aquatic environment, which inevitably accumulate metals, and then alter their migration. Whereas, the synergistic behavior and effect of microplastics and Hg(II) were rarely reported. In this context, the adsorptive behavior of Hg(II) by pristine/aged microplastics involving polystyrene, polyethylene, polylactic acid, and tire microplastics were investigated via kinetic (pseudo-first and second-order dynamics, the internal diffusion model), Langmuir, and Freundlich isothermal models; the adsorption and desorption behavior was also explored under different conditions. Microplastics aged by ozone exhibited a rougher surface attached with abundant oxygen-containing groups to enhance hydrophilicity and negative surface charge, those promoted adsorption capacity of 4-20 times increment compared with the pristine microplastics. The process (except for aged tire microplastics) was dominated by a monolayer chemical reaction, which was significantly impacted by pH, salinity, fulvic acid, and co-existing ions. Furthermore, the adsorbed Hg(II) could be effectively eluted in 0.04% HCl, simulated gastric liquids, and seawater with a maximum desorption amount of 23.26 mg/g. An artificial neural network model was used to predict the performance of microplastics in complex media and accurately capture the main influencing factors and their contributions. This finding revealed that aged microplastics had the affinity to trap Hg(II) from freshwater, whereafter it released the Hg(II) once transported into the acidic medium, the organism's gastrointestinal system, or the estuary area. These indicated that aged microplastics could be the sink or the source of Hg(II) depending on the surrounding environment, meaning that aged microplastics could be the vital carrier to Hg(II).

Bacitracin-Engineered BSA/ICG Nanocomplex with Enhanced Photothermal and Photodynamic Antibacterial Activity.

To reduce the drug resistance of bacteria and enhance the antibacterial ability in bacterial infection therapy, we designed a new antibacterial nanoagent. In this system, a photosensitizer (indocyanine green, ICG) was loaded in bovine serum albumin (BSA) through hydrophobic-interaction-induced self-assembly to form stable BSA@ICG nanoparticles. Furthermore, a positively charged antibacterial peptide bacitracin (Bac) was physically immobilized onto the surface of BSA@ICG to generate a bacterial-targeted nanomedicine BSA@ICG@Bac through electrostatic interactions. Afterward, its photodynamic and photothermal activities were intensely evaluated. Moreover, its bactericidal efficiency was assessed via in vitro antibacterial assays and bacterial biofilm destruction tests. First, the obtained BSA@ICG@Bac showed both good singlet oxygen generation property and high photothermal conversion efficiency. In addition, it showed enhanced photodynamic and photothermal antibacterial capacities and biofilm-removing ability in vitro due to Bac modification. To sum up, our research provided an economic and less-time-consuming approach to preparing antibacterial nanomedicines with excellent antibacterial ability. Therefore, the prepared antibacterial nanomedicines have great potential to be utilized in clinical trials in the future.

Development and validation of the DGT technique using the novel cryogel for measuring dissolved Hg(II) in the estuary.

The complex seawater matrix has significantly influenced the determination of estuarine dissolved Hg(II), hindering its monitoring and risk assessment in maricultural areas. In this work, SiO2-SH-DGT assembled by the sulfhydryl-modified silica cryogel (SiO2-SH cryogel) as the novel binding phase was developed to tackle this problem. The uniform dispersion of the cryogel into binding gel was advantageous for achieving remarkable and comparable capacity, which endowed the estimated diffusion coefficient (D) to be 1.39-3.08 times of the existing research. The SiO2-SH-DGT performance was independent of pH (3-9), ionic strength (10-800 mM), fulvic acid at low content, and seawater matrix (Na+, K+, Ca2+, Cl-), but the high content of Mg2+ did interfere with the Hg(II) accumulation, which manifested as competitive adsorption and diffusion. Therefore, the calibrated model was established by calibrating accumulated mass (M') and diffusion coefficient (D') based on the Mg2+ concentration, its high accuracy was further verified in the lab. Finally, SiO2-SH-DGT was deployed in the three typical aquaculture areas in Beibu Gulf, field trials achieved the actual Hg(II) level to be 1.52-5.38 ng/L with consideration of the diffusion boundary layer. The finding could provide new thought and technical support for metal pollution monitoring in estuary maricultural areas.

Voltage-Controlled Antiferromagnetism in Magnetic Tunnel Junctions.

We demonstrate a voltage-controlled exchange bias effect in CoFeB/MgO/CoFeB magnetic tunnel junctions that is related to the interfacial Fe(Co)O_{x} formed between the CoFeB electrodes and the MgO barrier. The unique combination of interfacial antiferromagnetism, giant tunneling magnetoresistance, and sharp switching of the perpendicularly magnetized CoFeB allows sensitive detection of the exchange bias. We find that the exchange bias field can be isothermally controlled by magnetic fields at low temperatures. More importantly, the exchange bias can also be effectively manipulated by the electric field applied to the MgO barrier due to the voltage-controlled antiferromagnetic anisotropy in this system.

Electric-field-assisted switching in magnetic tunnel junctions.

The advent of spin transfer torque effect accommodates site-specific switching of magnetic nanostructures by current alone without magnetic field. However, the critical current density required for usual spin torque switching remains stubbornly high around 10(6)-10(7) A cm(-2). It would be fundamentally transformative if an electric field through a voltage could assist or accomplish the switching of ferromagnets. Here we report electric-field-assisted reversible switching in CoFeB/MgO/CoFeB magnetic tunnel junctions with interfacial perpendicular magnetic anisotropy, where the coercivity, the magnetic configuration and the tunnelling magnetoresistance can be manipulated by voltage pulses associated with much smaller current densities. These results represent a crucial step towards ultralow energy switching in magnetic tunnel junctions, and open a new avenue for exploring other voltage-controlled spintronic devices.

Percutaneous endoscopic gastrostomy/jejunostomy combined with percutaneous transhepatic biliary drainage in treating malignant biliary obstruction.

OBJECTIVE: To investigate the safety and efficacy of percutaneous endoscopic gastrostomy/jejunostomy (PEG/PEJ) combined with percutaneous transhepatic biliary drainage (PTCD) in treating malignant biliary obstruction. SUBJECTS AND METHODS: Nine patients (6 males and 3 females, average age 71.3 ± 5.5 years) with complete obstruction of the biliary tract were treated with PEG/PEJ after PTCD. The PEG/PEJ and PTCD tubes were linked outside of the abdominal wall to direct the externally drained bile back to the jejunum through the PEG/PEJ intestinal tube. Clinical symptoms and liver function were assessed following the treatment. RESULTS: The operations were successfully completed in the 9 patients within 40 min (average 35 ± 2.9 min). Clinical symptoms such as jaundice, abdominal distension, stomachache and diarrhea appeared but improved within 7 days of the operation. Serum levels of bilirubin, aspartate aminotransferase and alanine aminotransferase were reduced (p < 0.01) 4 weeks following the treatment. There were no procedural complications. CONCLUSIONS: Combined PEG/PEJ and PTCD appeared to be safe and effective in the management of malignant biliary obstruction. Further, larger-scale studies will be needed to verify findings of this report.

[Ultrastructural changes of duodenal mucosas and their significance in patients with liver cirrhosis].

OBJECTIVE: To investigate the ultrastructural changes of duodenal mucosas and their significance in patients with liver cirrhosis (PLC). METHODS: Endoscopic biopsy duodenal mucosa specimens of 60 PLC and 18 healthy volunteers as controls were obtained. Ultrastructural changes of them were studied with transmission electron microscopy. These PLC were divided into groups A, B and C according to the Child-Pugh classification. The ultrastructural changes in the duodenal mucosas of each group were rated and compared with those of the other groups. PLC with and without ultrastructural changes of duodenal mucosas were divided into a positive group and a negative group. Levels of plasma Alb, TBil, PT, plasma endotoxin, and blood ammonia of the PLC were detected and compared. RESULTS: There were 20 PLC each in groups A, B, and C. Ultrastructural changes of duodenal mucosas were found in 5 PLC of group A, 9 in group B and 17 in group C. Among the 60 PLC, 52% had some changes in their duodenal mucosas. The changes included decrease and rupture of the microvilli; also karyopyknosis, karyorrhexis, widening of the gaps of the tight junction and tumefactions of mitochodrion of duodenal mucosa epithelial cells. No ultrastructural changes of duodenal mucosas were found in the control group. The rate of changes in the three Child-Pugh class groups and in the control group were 25%, 45%, 85%, 0% respectively (P < 0.01). The level of Alb of the positive group was significantly lower than that of the negative group (P < 0.01). Levels of plasma TBil, PT, endotoxin and blood ammonia of the positive group were significantly higher or longer than those of the negative group (P < 0.01). Levels of plasma Alb of the positive and negative groups were significantly lower than those of the control group (P < 0.01). Levels of TBil, PT, plasma endotoxin and blood ammonia of the positive and negative groups were significantly higher or longer than those of the control group (P < 0.01). CONCLUSION: There were ultrastructural changes of duodenal mucosas in PLC, especially in end-stage PLC. Ultrastructural changes of intestinal mucosas in the PLC may have important pathophysiological and clinical significance.

Acetylcholine and choline dynamics provide early and late markers of traumatic brain injury.

We assessed acetylcholine (ACh) and choline (Ch) dynamics 2.5 h, 1, 4 and 14 days after cerebral cortex impact injury or craniotomy only in adult male Sprague-Dawley rats. Cortical endogenous ACh (D0ACh), endogenous free Ch (D0Ch), deuterium-labeled Ch (D4Ch), and ACh synthesized from D4Ch (D4ACh) were measured by gas-chromatography mass-spectrometry after intravenous injection of D4Ch followed in 1 min by microwave fixation of the brain. D0Ch increased in and around the impact up to 700% of control within 1 day after trauma. Smaller D0Ch increases were found in the cortex contralateral to the impact and in both hemispheres after craniotomy only. D4Ch contents increased to 200% in the impact and surrounding regions 4-14 days post-trauma, with lower increases 2.5 h post-trauma. D0ACh decreased at all times post-trauma in the impact center, and initially in the periphery and adjacent regions with a recovery at 14 days. Similar D0ACh decreases, although of lesser extent and magnitude were present in the craniotomy only group. D4ACh showed a peak at one day post-trauma in all regions studied in the impact and craniotomy groups. In conclusion, D0Ch tissue level was an early marker of trauma, while 14 days after trauma Ch uptake from blood was enhanced in and around the traumatized cortex. Craniotomy by itself induced a generalized increase in ACh turnover 1 day after this minimal trauma. Choline acetyltransferase activity was reduced in the impact center region but not affected in the adjacent and contralateral regions or by craniotomy.