Search

Semiconducting single-walled carbon nanotubes (s-SWNTs) show great promises in advanced electronics. However, contact resistance between the nanotubes and metal electrode has long been a bottleneck to the development of s-SWNTs in high-performance electronic devices. Here we demonstrate a simple and controllable strategy for enhancing the electrode contact and therefore the performance of s-SWNT thin film transistors by plasma etching treatment, which effectively removes the polymer residues, including the photoresist and the conjugated molecules, adsorbed on the surface of s-SWNTs. As a result, the contact resistance is reduced by 3 times and the carrier mobility rises by up to 70%. Our method is compatible with current silicon semiconductor processing technology, making it a viable effective approach to large-scale application of s-SWNTs in the electronics industry.

The sorption of pharmaceuticals and personal care products (PPCPs) on soil and soil components makes an important contribution to the fate, migration and bioavailability of PPCPs. Previous reviews have mostly focused on the sorption of PPCPs on single soil components (e.g., minerals and soil organic matter). However, the sorption of PPCPs within the whole soil system has not been systematically analyzed. This paper reviews the recent progress on PPCP sorption on soil and soil components. We have evaluated the sorption of a wide range of PPCPs in research fields that are usually considered in isolation (e.g., humic acids (HAs), montmorillonite, kaolinite, and goethite), and established a bridge between PPCPs and sorbent. The sorption mechanisms of PPCPs, e.g., cation exchange, surface complexation, electrostatic interaction and hydrogen bonding, are discussed and critically evaluated. We also assessed the influence of environmental factors (pH, ionic strength, organic matter and temperature) on sorption. This review summarizes the knowledge of PPCPs sorption on soil gained in recent years, which can provide new strategies for solving the problem of antibiotic pollution.

Chemical investigation of secondary metabolites from the endophytic fungus Pseudopestalotiopsis theae led to the isolation of eighteen new polyketide derivatives, pestalotheols I&ndash, Q (1&ndash, 9) and cytosporins O&ndash, W (15&ndash, 23), together with eight known analogs (10&ndash, 14 and 24&ndash, 26). The structures of the new compounds were elucidated by HRMS and 1D and 2D NMR data, as well as by comparison with literature data. Modified Mosher&rsquo, s method was applied to determine the absolute configuration of some compounds. Compound 23 showed significant cytotoxicity against the mouse lymphoma cell line L5178Y with an IC50 value of 3.0 &mu, M. Furthermore, compounds 22 and 23 showed moderate antibacterial activity against drug-resistant Acinetobacter baumannii (ATCC BAA-1605) in combination with sublethal colistin concentrations.

Anaerobic digestion (AD) is an effective way to improve the utilization of food waste (FW). Activated persulfate is a powerful oxidant. This research investigated the effect of activated persulfate on gas production from FW AD. Three activation methods including heating, lighting, and ultrasonication were used. The results showed that the addition of activated persulfate promoted gas production from FW AD. And the main biogas composition were CH4, CO2, and N2. The difference in SO42− concentration further verified the effect of activated methods on producing sulfate free radicals by heating, lighting and ultrasonication from persulfate. The activated persulfate enhanced gas production by improving the organic hydrolysis. Relatively, lighting and ultrasonication were better than heating in persulfate activation. At the same time, the accumulated gas volumes from ultrasonication (587 mL) and lighting (574 mL) were significantly higher than that in heating (478 mL). The environmental impact assessment and economic assessment suggests that the addition of activated persulfate in FW AD is beneficial because of the lower secondary pollution, lower cost and higher additional value.

Plastics pollution in global soil systems is becoming a severely global issue and potential threat to terrestrial ecosystem serves and human health. Herein, in order to determine the degradability and ecological effects of polyethylene (PE) films, we measured the weight loss and characterization of PE films and analyzed variation in microbial community. The results of weight loss, SEM and FTIR spectra exhibited that PE films had unique degradation performance under different conditions. Simultaneously, we investigated the effects of PE films on the microbial community, and the microbiota colonizing on plastics. PE films may change the soil microbial community composition in soil, and hold the post of unique matrix for microbial colonization. These results indicate that the degradation of PE films and microbial community composition in soil can be affected by different conditions (soil layer, time and plants). By assessing the alteration of microbial community composition and PE films in soil, this work will contribute to enhance our understanding on the potential risks of plastics on soil ecosystems and provide a scientific basis for understanding the ecological effect of plastics on soil functions.

Ten new germacrane-type sesquiterpenoids (1–10) were isolated from a whole plant extract of Eupatorium chinense. The structures were elucidated by analysis of their NMR and MS data as well as by comparison with literature values. The absolute configuration of eupachinsin A (1) was determined by single-crystal X-ray diffraction analysis. Compounds 3 and 4 exhibited cytotoxicity against a human breast cancer cell line (MDA-MB-231), with IC50 values of 0.8 and 3.4 μM, respectively. In addition, compounds 3–5 showed cytotoxicity against the human hepatocellular carcinoma cell line (HepG2), with IC50 values ranging from 3.6 to 7.6 μM.

Three new terpenoids compounds ( 1–3 ) were obtained from ethyl acetate fraction, which was yielded from Eupatorium chinense ’ s ethanol extract . Their structures were determined on the basis of 1D and 2D NMR spectroscopy, including 1 H- 1 H COSY, HMBC, HSQC and NOESY experiments. All of the isolated compounds were tested in vitro for their cytotoxic activities against the HepG 2 , HGC-27 and MDA-MB-231 cancer cell lines.

High-purity semiconducting single-walled carbon nanotubes (s-SWNTs) can be obtained by conjugated polymer wrapping. However, further purification of sorted s-SWNTs and high costs of raw materials are still challenges to practical applications. It is inevitable that a lot of polymers still cover the surface of s-SWNTs after separation, and the cost of the polymer is relatively higher than that of SWNTs. Here, we demonstrated a facile isolated process to improve the quality of s-SWNT solutions and films significantly. Compared with the untreated s-SWNTs, the contact resistance between the s-SWNT and the electrode is reduced by 20 times, and the thin-film transistors show 300% enhancement of current density. In this process, most of the polymers can be recycled and reused directly without any purification, which can greatly decrease the cost for s-SWNT separation. The results presented herein demonstrate a new scalable and low-cost approach for large-scale application of s-SWNTs in the electronics industry.

In this study, tofu and egg white, representing typical protein-rich substrates in food waste based on vegetable and animal protein, respectively, were investigated for producing volatile fatty acids (VFAs) by acidogenic fermentation. VFA production, composition, conversion pathways and microbial communities in acidogenesis from tofu and egg white with and without hydrothermal (HT) pretreatment were compared. The results showed HT pretreatment could improve the VFA production of tofu but not for egg white. The optimum VFA yields were 0.46g/gVS (tofu with HT) and 0.26g/gVS (egg white without HT), respectively. Tofu could directly produce VFAs through the Stickland reaction, while egg white was converted to lactate and VFAs simultaneously. About 30-40% of total protein remained in all groups after fermentation. Up to 50% of the unconverted soluble protein in the HT groups was protease. More lactate-producing bacteria, mainly Leuconostoc and Lactobacillus, were present during egg white fermentation.

Microplastics are formed by the degradation of plastic wastes under the action of physicochemical mechanisms in environment, and they are becoming a new type of pollutant that is attractings global attention. However, research on the aging characteristics and mechanism of microplastics is limited. The aging mechanism of Polystyrene (PS) with UV irradiation under different conditions (air, pure water and seawater) and the effect of aging on heavy metal adsorption were studied. The results show that PS have different characteristics with UV irradiation under different conditions, and the aging of PS is the most obvious in air. Based on the 2D-COS analysis, different aging mechanisms were identified under different aging conditions, aging sequence of aged PS functional groups in air and water were clearly definited. An isothermal adsorption model shows that aging can significantly increase the adsorption of heavy metals by PS. The adsorption of heavy metals is also affected by different aging methods. Over all, a 2D-COS analysis was an effective method for understanding the aging process of PS. These results further clarify the aging mechanism of PS, and provides a theoretical basis for the assessment of environmental behavior and ecological risk when microplastics and heavy metals coexist.

Ten new ambuic acid derivatives, pestallic acids H–Q including one new iodinated natural product along with two known compounds, ambuic acid and ambuic acid 18-acetate, were obtained through fermentation of the endophytic fungus Pestalotiopsis lespedezae on solid rice medium with 3.5% NaI. Pestallic acids H–Q were undetectable in cultures of the fungus grown on solid rice medium lacking NaI or in those where NaI had been replaced by NaCl or NaBr. The structures of the new metabolites were established on basis of 1D/2D NMR and HRESIMS data. Their absolute configurations were determined by Mosher’s method and TDDFT-ECD calculations. The compounds failed to show antibacterial activity against S. aureus (ATCC29213), drug-resistant Acinetobacter baumannii (BAA1605) or Mycobacterium tuberculosis, as well as cytotoxicity against the mouse lymphoma cell line L5178Y.

Microplastics are widespread in the environment and might transport readily by ocean currents, wind and atmospheric deposition. Simultaneously, antibiotics and heavy metals could often be detected in the environment. They are both positively charged, it is necessary to clarify the interactions of these pollutants with microplastics when they were coexist. In this study, the most commonly used polystyrene (PS) was selected as a representative microplastic. This study investigated the effect of Cd(II) on the sorption of TYL by PS in different coexistence systems. The results showed that: in the composite system, when TYL and Cd(II) coexist, the presence of Cd(II) could inhibit the sorption of TYL by PS, and the inhibitory effect increases with the increase of the concentration of Cd(II), indicating that competitive sorption dominates the sorption. When PS adsorbed Cd(II) first and then adsorbed TYL, the presence of Cd(II) was conducive to the sorption of TYL, and the sorption strengthened with the increase of Cd(II) concentration, indicating that the complexation between TYL and Cd(II) enhanced the sorption of TYL. In addition, initial pH values and ionic strength were essential in the sorption process. Therefore, this study could provide an important basis for evaluating the environmental behavior and ecological risk of microplastics in the process of compound pollution.

Food waste is ideal for producing energy and value-added chemicals (e.g., biohydrogen and volatile fatty acids (VFAs)) in biorefineries. The main food waste components are carbohydrates, proteins, and lipids. Three substrates (glucose, peptone, and glycerol, representing carbohydrates, proteins, and lipids, respectively) were acidogenically fermented in this study. For each substrate, we investigated fermentation type and VFAs produced. We used a stoichiometric approach to identify the metabolic pathways through which the substrates were converted. The maximum VFA concentrations for glucose, peptone, glycerol, and a mixture were 38.2, 32.2, 31.1, and 38.5 gCOD/L, respectively. Mixing the substrates increased VFA production, indicating that synergistic effects between microorganisms improved acidogenic fermentation. Different fermentation types occurred for different substrates. Butyric, acetic, and propionic acids were the main products for glucose, peptone, and glycerol, respectively. Glucose was metabolized through three pathways. The metabolism of glycerol was similar to glucose through the “glycerol-pyruvate-VFA” pathway.

To remove dispersant molecules on the surface of single-walled carbon nanotubes (SWCNTs) is one of main challenges for its practical application in electronics. In this paper, we demonstrated a photodegradable process as a promising method to remove off the dispersants from the surface of semiconducting SWCNTs (s-SWCNTs). A N-heterocyclic aromatic compound, 1,2,5,6-Tetra(5-octylthiophene-2-yl)-Hexaazapentacene (noted as 4HP-C8), was synthesized and used to enrich s-SWCNTs with high yield and purity. Importantly, 4HP-C8 was found to be sensitive to UV irradiation and therefore could be photodegraded into fragments, which provided a facile approach to harvest “dispersant-free” s-SWCNTs. The degradation process and reaction kinetics of 4HP-C8 were also carefully investigated.

Microplastics released into the environment undergo a variety of aging processes, however, information about the influence of aging on the adsorption behavior of microplastics is limited. In order to better understand the effect of aging polystyrene (PS) on the ability to adsorb heavy metal, H2O2 and Fenton reagent were used to investigate the aging properties of PS. Aging PS with these two different aging agents at pH = 4 and room temperature for the same time. Physical and chemical characterization indicated that aging caused oxidation of the surface of PS and the formation of surface micro-cracks. Based on the 2D-COS analysis, the aging process of PS functional groups could occur in the following sequence: 1375 (C-OH) > 1739 (C=O) > 1182 cm−1 (C−O−C) > 1716 (O−C=O). The adsorption experiments for Cd2+ with two different concentrations were carried out by PS with different aging time at room temperature. The adsorption data showed that the adsorption capacity of Cd2+ was significantly enhanced after aging compared with pristine PS, and the adsorption capacity of PS after Fenton aging treatment is much stronger than that after H2O2 aging treatment. The kinetic analysis of the adsorption data indicates that the adsorption process is more consistent with the second-order kinetics than the first-order kinetics, and it is further concluded that the adsorption of Cd2+ by PS is a relatively complicated process. According to the fitting results of adsorption isotherms, the adsorption process of pristine PS mainly occurs on the surface, but with the continuous aging, more adsorption sites may be exposed on the surface of PS, so it can be concluded that the adsorption mechanism of Cd2+ by PS is the coexistence of physics and chemistry. This study indicates aging microplastics may have a significant impact on the destination and migration of metal contaminants, which deserves to be further concerned.

Based on our previous study, the low volatile fatty acid (VFA) production from egg white in food waste was mainly attributed to more acidogenic substrates (proteins and amino acids) consumed in the Maillard reaction and more organics converted into lactic acid. In this study, two methods were employed to improve VFA production: (1) reducing Maillard reaction with a drop in pH during hydrothermal (HT) pretreatment, and (2) inhibiting the conversion from protein to lactic acid. HT pretreatment under weakly acidic condition significantly promoted the hydrolysis and degradation of protein and the hydrolytic enzyme (protease) activity, thus increasing VFA yield by 45.8% from 0.24 to 0.35 g/g protein for HT pretreated egg white. Addition of sodium oxamate increased the maximal VFA yield from 0.24 to 0.29 g/g protein for HT pretreated egg white and from 0.32 to 0.67 g/g protein for egg white with no pretreatment in which there was more protein converted through the lactic acid metabolism pathway. Sodium oxamate improved the acidification step by inhibiting the reaction from pyruvates to lactic acid, and thereby accelerating the process of conversion from pyruvates to VFA.

Electrical hysteresis in carbon nanotube thin-film transistor (CNTTFT) due to surface adsorption of H2O/O2 is a severe obstacle for practical applications. The conventional encapsulation methods based on vacuum-deposited inorganic materials or wet-coated organic materials have some limitations. In this work, we develop a general and highly efficient dry-laminating encapsulation method to reduce the hysteresis of CNTTFTs, which may simultaneously realize the construction and encapsulation of CNTTFT. Furthermore, by virtue of dry procedure and wide compatibility of PMMA, this method is suitable for the construction of CNTTFT on diverse surface including both inorganic and organic dielectric materials. Significantly, the dry-encapsulated CNTTFT exhibits very low or even negligible hysteresis with good repeatability and air stability, which is greatly superior to the nonencapsulated and wet-encapsulated CNTTFT with spin-coated PMMA. The dry-laminating encapsulation strategy, a kind of technological innovation...

The Ascomycete fungus Aphanoascus fulvescens isolated from goose dung was investigated for its secondary metabolites, yielding five new indole alkaloids okaramines V–Z (1–5) and eleven known derivatives (6–16). Their structures were determined by 1D, 2D NMR spectra and HRMS data. Compounds 6, 8, 11 and 12 showed significant to moderate cytotoxicity against the mouse lymphoma cell line L5178Y with IC50 values ranging from 4.0 to 14.7 μM. Preliminary structure-activity relationships are discussed.

The aim of this study was to explore the effects of redox potential (ORP) and inoculum on volatile fatty acids (VFAs) production from food waste by acidogenic fermentation. Four experimental conditions with two ORP levels were tested: limited aeration conditions with ORP level of -100 to -200mV inoculating anaerobic sludge (LA+AnS) or aerobic sludge (LA+AeS), and anaerobic conditions with ORP level of -200 to -300mV inoculating anaerobic sludge with 2-bromoethanosulfophate (AN+BES) and without BES (AN). The maximal VFA yield (0.79g COD/g VS) was attained in LA+AnS reactor due to enhanced hydrolysis of substrates, especially proteins (degradation efficiency 78.3%). A higher frequency of phylum Firmicutes under limited aeration conditions (42.2-48.2%) was observed than that under anaerobic conditions (21.1%). The microbial community was more diverse in LA+AnS reactors than LA+AeS. We conclude that appropriate ORP level (from -100 to -200mV) and inoculum play essential roles in VFA production.

For the large-area fabrication of thin-film transistors (TFTs), a new conjugated polymer poly[9-(1-octylonoyl)-9H-carbazole-2,7-diyl] is developed to harvest ultrahigh-purity semiconducting single-walled carbon nanotubes. Combined with spectral and nanodevice characterization, the purity is estimated up to 99.9%. High density and uniform network formed by dip-coating process is liable to fabricate high-performance TFTs on a wafer-scale and the as-fabricated TFTs exhibit a high degree of uniformity.