Latest ArticlesIn this work, a modification method of H3PO4 plus H2O2 (PHP) was introduced to targetedly form abundant oxygenated functional groups (OFGs) on biochar, and methylene blue (MB) was employed as a model pollutant for adsorption to reflect the modification performance. Results indicated that parent biochars, especially derived from lower temperatures, substantially underwent oxidative modification by PHP, and OFGs were targetedly produced. Correspondingly, approximately 21.5-fold MB adsorption capacity was achieved by PHP-modified biochar comparing with its parent biochar. To evaluate the compatibility of PHP-modification, coefficient of variation (CV) based on MB adsorption capacity by the biochar from various precursors was calculated, in which the CV of PHP-modified biochars was 0.0038 comparing to 0.64 of the corresponding parent biochars. These results suggested that the PHP method displayed the excellent feedstock compatibility on biochar modification. The maximum MB adsorption capacity was 454.1 mg/g when the H3PO4 and H2O2 fraction in PHP were 65.2% and 7.0%; the modification was further intensified by promoting temperature and duration. Besides, average 94.5% H3PO4 was recovered after 10-batch modification, implying 1.0 kg H3PO4 (85%) in PHP can maximally modify 2.37 kg biochar. Overall, this work offered a novel method to tailor biochar towards OFGs-rich surface for efficient adsorption.
Nicotine ingested from smoking exerts neuroprotection and developmental neurotoxicity in central nervous system. It can produce several changes of cognitive behaviors through regulating the release of different neurotransmitters in the brain. However, the effects of nicotine exposure or withdrawal on neurotransmitter metabolism of hippocampus are still unclear. In this study, we real-time evaluated the dynamic alterations in neurotransmitter metabolism of hippocampal neuronal (HT22) cells induced by nicotine exposure and withdrawal at relevant exposure levels of smoking and secondhand smoke by using a microfluidic chip-coupled with liquid chromatography-mass spectrometry (MC-LC-MS) system. We found HT22 cells mainly released related neurotransmitters of tryptophan and choline metabolism, both nicotine exposure and withdraw altered its neurotransmitters and their metabolites release. Exposure to nicotine mainly altered the secretion of serotonin, kynurenic acid, choline and acetylcholine of HT22 cells to improve hippocampal dependent cognition, and the change are closely related to the dose and duration of exposure. Moreover, the altered metabolites could rapidly recover after nicotine withdrawal, but picolinic acid was elevated. MC-LC-MS system used in present study showed a greater advantage to detect unstable metabolites than conventional method by using in vitro model, and the results of dynamic alterations of neurotransmitter metabolism induced by nicotine might provide a potential targets for drug development of neuroprotection or cognitive improvement.
Considering that cathode of microbial electrochemical system (MES) is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms, and that Fe(0) is also a confirmed electron donor for some electroactive microorganisms through metal-microbe direct electron transfer (DET), Fe(0)-cathode was equipped into an MES digester to enhance cathodic methane production. The results of this study indicated that the potential DET participator, Clostridium possibly obtained electrons directly from Fe(0)-cathode via metal-microbe electrons transfer, then transferred electrons directly to the definite DET participators, Methanosarcina/Methanothrix via microbe-microbe electrons transfer for CH4 production. In addition, Methanobacterium is another specially enriched methanogen on Fe(0)-cathode, which might obtain electrons directly from Fe(0)-cathode to produce CH4 via metal/electrode-microbe DET. The increment of conductivity of cathodic sludge in Fe(0)-cathode MES digester (R1) further confirmed the enrichment of electroactive microorganisms participating in DET process. As a consequence, a higher CH4 production (1205–1508 mL/d) and chemical oxygen demand (COD) removal (79.0%-93.8%) were achieved in R1 compared with graphite-cathode MES digester (R2, 720–1090 mL/d and 63.6%-85.6%) and the conventional anaerobic digester (R3, 384–428 mL/d and 35.2%-41.0%). In addition, energy efficiency calculated indicated that the output energy of CH4 production was 8.16 folds of electricity input in Fe(0)-cathode MES digester.
The nitrogen-doped carbon derived from graphitic carbon nitride (g-C3N4) has been widely deployed in activating peroxymonosulfate (PMS) to remove organic pollutants. However, the instability of g-C3N4 at high temperature brings challenges to the preparation of materials. The nitrogen-doped graphitic carbon nanosheets (N-GC750) were synthesized by magnesium thermal denitrification. Magnesium undergoes the displacement reaction with small molecules produced by the pyrolysis of g-C3N4, thereby effectively fixing carbon on the in-situ template of Mg3N2 and avoiding direct product volatilization. N-GC750 exhibited excellent performance during the PMS activation process and bisphenol A (BPA, 0.2 g/L) could be thoroughly removed in 30 min. A wide range of pH (3–11), temperature (10–40 ℃) and common anions were employed in studying the impact on system. Additionally, N-GC750 showed satisfactory reusability in cycle tests and promising applicability in real water samples. Quenching experiments and electron paramagnetic resonance (EPR) measurements indicated that singlet oxygen was the main active species coupled with partial electron transfer in N-GC750/PMS system. Furtherly, the oxidation products were identified, and their ecotoxicity was evaluated. This work is expected to provide a reference for the feasibility of preparing g-C3N4 derived carbon materials and meaningful for PMS activation.
Fabrication of selective adsorption coatings plays a crucial role in solid-phase microextraction (SPME). Herein, new strategies were developed for the in-situ fabrication of novel cobalt-based carbonaceous coatings on the nickel-titanium alloy (NiTi) fiber substrate using ZIF-67 as a precursor and template through the chemical reaction of ZIF-67 with glucose, dopamine (DA) and melamine, respectively. The adsorption performance of the resulting coatings was evaluated using representative aromatic compounds coupled to high-performance liquid chromatography (HPLC) with ultraviolet detection (HPLC-UV). The results clearly demonstrated that the adsorption selectivity was subject to the surface elemental composition of the fiber coatings. The cobalt and nitrogen co-doped carbonaceous coating showed better adsorption selectivity for ultraviolet filters. In contrast, the cobalt-doped carbonaceous coating exhibited higher adsorption selectivity for polycyclic aromatic hydrocarbons. The fabricated fibers present higher mechanical stability and higher adsorption capability for model analytes than the commercial polydimethylsiloxane and polyacrylate fibers. These new strategies will continue to expand the NiTi fibers as versatile fiber substrates for metal-organic frameworks (MOFs)-derived coating materials with controllable nanostructures and tunable properties.
High performance liquid chromatography-mass spectrometry is one of the most commonly used strategies for lipid analysis. The development of versatile chromatographic stationary phases to meet the increasing demands for separation of complex lipids is very important. Styrene-maleic acid (SMA) copolymer is an amphiphilic polymer, which has been proven to have the ability to solubilize lipid molecules of various structures. In this study, styrene-maleic anhydride copolymer coated silica was first prepared by the thiol-ene click reaction. With l-cysteine hydrochloride or dodecanol as the post-modification reagents, Sil-SMA-amino acid and Sil-SMA-dodecanol stationary phase materials were further successfully fabricated via nucleophilic ring-opening reaction. The Fourier-transform infrared, thermogravimetric analysis, and elemental analysis results confirmed the two stationary phase materials were successfully prepared. Furthermore, both the Sil-SMA-dodecanol column and the Sil-SMA-amino acid column possessed reversed-phase/hydrophilic interaction/ion exchange mixed-mode retention mechanisms. The column efficiency of the Sil-SMA-derivatives columns reached 77,300 N/m. Based on the mixed-mode retention characteristics, the Sil-SMA-derivatives columns achieved both the lipid classes and species separation via a single column. The Sil-SMA-amino acid column was further successfully used to separate lipid extract from gastric cancer cell membrane. All these results demonstrated that the SMA-based stationary phase materials have a good potential for use in lipid separation.
The efficient remediation of heavy metal complexes in water has become a difficult and challenging task owing to their high stability and strong mobility. In this study, a novel strategy was employed for highly efficient removal of Cu-citrate by using intimately coupled photocatalysis and biodegradation (ICPB) system with non-woven cotton fabric as a carrier. Experimental results showed that the ICPB system caused 94% Cu removal, which was higher than those of single photocatalysis. After 5 cycles, Cu removal efficiency could still reach 78% within 5 h. The existence of 0–40 mg/L citrate had negligible influence, whereas the presence of 60–100 mg/L citrate exhibited a limited adverse effect on Cu removal (~70%). The decomplexation of Cu-citrate was realized via the function of free radicals and microorganisms. Two main processes, such as bio-adsorption of Cu2+ by microorganisms, deposition of Cu0 on the surface of material, played important role in Cu removal from aqueous solution. The dominant microorganisms in the system were Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Chlorophyta, Planctomycetes, and Verrucomicrobia. Furthermore, the performance of ICPB system was also validated through treatment of other heavy metal complexes. This study provided a feasible strategy for the decontamination of heavy metal complexes in wastewater.
Concentration gradient and fluid shear stress (FSS) for cell microenvironment were investigated through microfluidic technology. The Darcy–Weisbach equation combined with computational fluid dynamics modeling was exploited to design the microfluidic chip, and the FSS distribution on the cell model with varying micro-channels (triangular, conical, and elliptical). The diffusion with the incompressible laminar flow model by solving the time-dependent diffusion–convection equation was applied to simulate the gradient profiles of concentration in the micro-channels. For the study of single cell in-depth, the FSS was investigated by the usage of polystyrene particles and the concentration diffusion distribution was studied by the usage of different colors of dyes. A successful agreement between model simulations and experimental data was obtained. Finally, based on the established method, the communication between individual cells was envisaged and modeled. The developed method provides valuable insights and allows to continuously improve the design of microfluidic devices for the study of single cell, the occurrence and development of tumors, and therapeutic applications.
Gestational diabetes mellitus (GDM), a frequently-occurring disease during pregnancy, may cause some adverse healthy outcome of both mother and offspring. However, the knowledge about metabolite alterations during the pathogenesis and development process is limited. Here, a large longitudinal non-targeted metabolomics study of 195 pregnant women (64 women with subsequently developed GDM and 131 healthy controls) was conducted. Each participant provided urine samples at three timepoints during early, middle and late pregnancy, respectively. The metabolic profiles of 585 urine samples (195 × 3) were measured by using ultra-high performance liquid chromatography coupled with Orbitrap high-resolution mass spectrometry. Among the 56 identified metabolites, the levels of eight metabolites increased and three ones decreased in the first trimester, the concentration of one metabolite increased and those of 20 decreased in the second trimester, as well as the levels of five metabolites increased and two decreased in the third trimester. After false discovery rate correction, the levels of valine and 5-acetamidovalerate in GDM group significantly increased in the first trimester, the levels of 1-methylguanine and 1, 3-dihydro-(2H)-indol-2-one significantly decreased in the second trimester and three metabolites (threonine, OH-octanedioyl-carnitine and pimelylcarnitine) increased and N-acetyltryptophan decreased in the third trimester, respectively. Six metabolites, such as pantothenic acid and threonine, had significant interaction effects between gestational stage (different trimester) and group (GDM or control). The differential metabolites were involved in "tryptophan metabolism", "purine metabolism", "valine, leucine and isoleucine degradation" and other pathways. The findings may provide insights into further pathogenesis study of GDM.
The simplification of localized surface plasmon resonance (LSPR) detection can further promote the development of optical biosensing application in point-of-care testing. In this study, we proposed a simple light emitting diode (LED) based single-wavelength LSPR sensor modulated with bio-electron transfers for the detection of electroactive biomolecules. Indium tin oxide electrode loaded with nanocomposites of polyaniline coated gold nanorod was used as LSPR chip, and the applied electric potential was scanned at the LSPR chip for single-wavelength LSPR biosensing. Under the scanning of applied potentials, biological electron transfer of redox reaction was employed to demonstrate the bioelectronic modulation of single-wavelength LSPR for selective electroactive biomolecule detection. Without any additional recognition material, electroactive biomolecules uric acid and dopamine were detected directly with a sensitivity of 5.05 μmol/L and 7.11 μmol/L at their specific oxidation potentials, respectively. With the simplified optical configuration and selective bioelectronic modulation, the single-wavelength LSPR sensor is promising for the development of simple, low-cost, and high specificity optical biosensor for point-of-care testing of electroactive biomolecules.
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