Enhanced permeate flux by air micro-nano bubbles via reducing apparent viscosity during ultrafiltration process

Micro-nano bubbles (MNBs) play important roles in the reduction of membrane fouling during membrane separation; however, such improvements are always attributed to the reduced concentration polarization on the surface of membranes and little attention has been paid on the variations of physicochemical properties of the feed caused by MNBs. In this study, the separation efficiencies of the feed containing humic acid (HA), bovine serum albumin (BSA), sodium alginate (SA) or dyes can be improved by MNBs during ultrafiltration, and the normalized fluxes can be maximally increased to 139% and 127% in the dead-end and cross-flow modes, respectively in the treatment of HA solution. We further reveal that the decreased apparent viscosity of the feed in the presence of MNBs is the key factor that enhances the normalized flux during ultrafiltration. This study gives new insight on the importance of MNBs in membrane separation and provides valuable clues for other chemical processes.

Mediation of water-soluble oligoaniline by phenol in the aniline-persulfate system under alkaline conditions

Although synthesis of oligoaniline (OANI) by persulfate and aniline has been investigated in the recent years, the impact of phenol on the synthesized soluble OANI is still not clear. In this study, our results indicate that phenol and pH mediate the production of the blue water-soluble OANI (OANI_blue) in the reaction between sodium persulfate (SPS) and aniline under alkaline conditions, and the yields of OANI_blue increase with increasing concentrations of phenol and pH values. Quenching experiments rule out the contributions of SO₄˙^- and ˙OH to aniline oxidation and imply that the non-radical activation of SPS is an important pathway in the formation of OANI_blue. MALDI-TOF-MS analysis indicates that phenol apparently inhibits the polymerization degree of aniline in that the molecular weights of OANI_blue gradually decrease from 1586.4 to 684.6 when phenol is increased from 0 to 2.0 mM. FTIR and Raman analyses confirm the structure of aniline oligomers in OANI_blue and indicate that phenol inhibits the phenazine-like structure in OANI_blue and facilitates the transformation of benzenoid rings to quinoid rings in the oxidation products. However, simultaneous activation of SPS by phenol and aniline is likely to occur in the reaction system with the formation of PhNH˙, as indicated by DFT calculations. The high scavenging reactivity of phenol towards both PhNH₂˙⁺ and PhNH˙ implies that PhNH₂˙⁺ and PhNH˙ are not the intermediates in the formation of OANI_blue. DFT calculations also reveal that apart from the one-electron transfer pathway between aniline and SPS, the two-electron transfer pathway is also likely to occur in the presence of phenol, resulting in the formation of PhNH⁺/PhN˙˙ without producing PhNH₂˙⁺ and PhNH˙. The produced PhNH⁺/PhN˙˙ intermediates then couple with aniline, PhNH⁺, aminophenyl sulfate and its hydrolysate to form dimers, trimers, oligomers, and eventually OANI_blue. This study not only describes a novel method to prepare water-soluble OANI, but also gives new insight on the importance of phenol in the production of OANI_blue.

[Progress in diagnosis and treatment of gangrenous cholecystitis]

Gangrenous cholecystitis is a kind of acute cholecystitis, whose course of disease progresses rapidly, early diagnosis is difficult and mortality is high, and clinicians are prone to misdiagnosis and missed diagnosis in clinical work.However, gangrenous cholecystitis has been ignored in various guidelines.This paper systematically summarized the pathogenesis, pathological manifestations, epidemiology, clinical diagnosis and treatment of gangrenous cholecystitis, hoping to provide a complete and clear diagnosis and treatment process for clinicians.

The fast redox cycle of Cu(II)-Cu(I)-Cu(II) in the reduction of Cr(VI) by the Cu(II)-thiosulfate system

Thiosulfate (S₂O₃^2-) is an important ligand to complex metal cations, however, the reactivity of metal-thiosulfate complexes has barely been mentioned. In this study, the reactivity of the Cu(II)-S₂O₃^2- system in the reduction of Cr(VI) was investigated. Kinetic results show that the reduction rates of Cr(VI) decrease with increasing pH values from 3.0 to 5.0, and 94.3% and 97.5% of 10 mg L^-1 Cr(VI) was rapidly reduced within 1 min at pH 3.0 and within 30 min at pH 5.0, respectively at the molar ratio of Cu(II):S₂O₃^2- of 0.05. We rule out the contributions of S species of tetrathionate (S₄O₆^2-) and sulfite (SO₃^2-) to Cr(VI) reduction and point out that the produced Cu(I) in the Cu(II)-S₂O₃^2- system is the key reductant that mediates the reduction of Cr(VI). We suggest that complexation between Cu(II) and S₂O₃^2- with the formation of Cu^II(S₂O₃)₂^2- is the pre-requisite for the formation of Cu^I(S₂O₃)_n^1-2n, which plays an important role in Cr(VI) reduction, accompanied by the re-oxidation of Cu(I) to Cu(II) by Cr(VI), achieving the rapid redox cycling of Cu(II)-Cu(I)-Cu(II). Such a redox cycle also mediates the denitrification process of NO₂^- to NH₃/NH₄⁺ under weakly acidic conditions. This study enriches our understanding on the reducing reactivity of the Cu(II)-S₂O₃^2- system and the importance of the Cu(II)-Cu(I)-Cu(II) redox cycle towards environmental oxidizing contaminants.

Selective oxidation of aniline contaminants via a hydrogen-abstraction pathway by Bi2·15WO6 under visible light and alkaline conditions

Conversion of aniline wastes to value-added products is always a promising method to treat aniline wastewater. In this study, a selective oxidation of aniline contaminants by Bi_2·15WO₆ was carried out under visible light and alkaline conditions. Kinetic results show that the oxidation rates of aniline increase with increasing pH values under visible light. UV-vis absorption spectra and GC-MS analysis confirm that azobenzene is the primary oxidation product with aminophenol and N,N'-diphenylhydrazine as the secondary products. The analyses from Mott-Schottky, electrochemical impedance spectroscopy (EIS), transient photocurrent and photoluminescence (PL) further indicate that OH^- promotes the separation and transfer of photogenerated electron-hole pairs on the surface of Bi_2·15WO₆, thus facilitating oxidation of aniline. Quenching experiments and electron spin resonance (ESR) analysis confirm that h⁺ is the predominant specie in the Bi_2·15WO₆ system and aniline radical cation (PhNH₂^•+) is an important intermediate. The Hammett and ΔBDE_N-H plots further reveal that e^- abstraction from aniline with the formation of PhNH₂^•+, followed by H⁺ abstraction from PhNH₂^•+ with the formation of anilino radicals (PhNH^•), is the prerequisite for the formation of N,N'-diphenylhydrazine, which is then oxidized to azobenzene via the hydrogen-abstraction pathway. This work provides a cost-effective method to selectively oxidize aniline to azobenzene.

Formation of hydroperoxo (-OOH) species on the surface of self-doped Bi2.15WO6: reactivity towards As(iii) oxidation

Bi2+xWO6 is a cost-effective and environmentally friendly photocatalyst that shows high reactivity in the oxidation of various contaminants under visible light. However, under alkaline conditions, the reactive oxidative species in the Bi2+xWO6 system are still not clear yet. In this study, it is observed that the oxidation rates of As(iii) increase with increasing pH values in the Bi2.15WO6 system. Photoluminescence and the Mott-Schottky analyses confirm that OH- promotes the separation and transfer of photogenerated electron-hole pairs over Bi2.15WO6, thus facilitating the oxidation of As(iii). Electron spin resonance spectra analysis and quenching experiments rule out contributions of •OH, O2˙-, 1O2 and superoxo species to As(iii) oxidation and indicate that surface -OOH and/or H2O2 are indeed the predominant species under alkaline conditions. The improved production of H2O2 by H-donors such as glucose and phenol, as well as the UV-vis diffuse reflectance and Raman analyses, further confirms the formation of surface -OOH on Bi2.15WO6 under alkaline conditions. In the dark, the significant higher oxidation rate of As(iii) by H2O2-Bi2.15WO6 than that by H2O2 alone reveals that surface -OOH, instead of H2O2, plays an important role in As(iii) oxidation. This study enriches our understanding of the diversity of reactive oxygen species (ROS) in the Bi2.15WO6 system and gives new insight into the mechanism involved in the oxidation of As(iii) under alkaline conditions.

[Progress in molecular mechanism of hepatolenticular degeneration induced by ATP7B gene mutation]

Hepatolenticular degeneration, also named Wilson disease, is an autosomal recessive genetic disease that characterized by copper metabolism disorder. WD mainly caused by the dysfunction of mutant ATP7B variants. This review summaries the mechanisms that different mutations affect the function of ATP7B, including inducing the mislocalization of mutant proteins, affecting the interactions between proteins or domains, regulating catalytic activity of ATP7B, and modifying the splicing of ATP7B gene. Further more, the genotype-phenotype correlation of a few mutations has been reviewed. Several mutations, such as p.R778L, are considered to be associated with more serious clinical symptoms, and the differences in environmental, diet, and lifestyle habits may also have effects on the susceptibility or the onset age of the patients. The research of the pathogenesis and clinical characterization of ATP7B gene mutations in the molecular level helps to deepen the understanding of WD, and suggests that personalized treatments should be used in future clinical practice.

Photoreductive dissolution of schwertmannite induced by oxalate and the mobilization of adsorbed As(V)

Schwertmannite (Sch), a poorly crystalline iron mineral, shows high sorption capacity to As(V). In this study, the effects of UV irradiation and oxalate on the dissolution of pure Sch, Sch with adsorbed As(V) [Sch*-As(V)] and subsequent mobilization of As(V) were investigated at pH 3.0. Under UV irradiation, the dissolved Fe(II) took the majority of the total dissolved Fe during the dissolution of Sch and Sch*-As(V). In the presence of oxalate, Fe(III)-oxalate complexes formed on Sch [or Sch*-As(V)] could be converted into Fe(II)-oxalate by photo-generated electrons under UV illumination, and more total dissolved Fe produced compared to that without oxalate. In the dark, total dissolved Fe reached the maximum value (42.64 mg L^-1 for Sch) rapidly and existed as Fe(III) predominately. In addition, UV irradiation has almost no effect on the mobilization of As(V) in Sch*-As(V) in the absence of oxalate. However, in the presence of oxalate, UV irradiation resulted in the mobilization of As(V) declined by 14-36.5 times compared to that in the dark. This study enhanced our understanding on the mobilization of As(V), and UV irradiation could contribute to the immobilization of As(V) on Sch in the aquatic environments containing oxalate.

[Progress in research of vaccination for patients with cancer]

Due to the tumor malignancy or immunosuppressive treatment, patients with cancer in general are more susceptible to vaccine-preventable infections. The types, timing, dose of vaccination or even the immunization program for them may differ from those for the normal persons. At present, it is recommended to use inactivated vaccines for patients with cancer rather than attenuated live vaccines, Vaccinations should be avoided during immunosuppressive therapy; patients with cancer should receive double dosage of hepatitis B vaccines and two doses of inactivated influenza vaccines yearly. This paper summarizes the progress in clinical trials of vaccination for cancer patients in foreign countries, and provide reference for the development and implementation of vaccination strategy for cancer patients in China.

As(III) removal and speciation of Fe (Oxyhydr)oxides during simultaneous oxidation of As(III) and Fe(II)

Abiotic oxidation of Fe(II) is an important pathway in the formation of Fe (oxyhydr)oxides. However, how can As(III) affect the oxidation rate of Fe(II) and the speciation of Fe (oxyhydr)oxides, and what's the extent of the newly formed Fe (oxyhydr)oxides on the removal of aqueous arsenic are still poorly understood. Oxidation of Fe(II) under neutral pH conditions was therefore investigated under different molar ratios of As:Fe. Our results suggest that co-existence of aqueous As(III) significantly slows down the oxidation rate of Fe(II). Speciation of Fe (oxyhydr)oxides is dependent on pH and As:Fe ratios. At pH 6.0, formation of lepidocrocite and goethite is apparently inhibited at low As:Fe ratios, and ferric arsenate is favored at high As:Fe ratios. At pH 7.0, lepidocrocite gradually degenerates with the increasing As:Fe ratios. At pH 8.0, arsenite significantly inhibits the development of magnetite and favors a formation of lepidocrocite. XPS analysis further reveals that more than half of As(III) is oxidized to As(V) at pH 6.0 and 7.0, whereas at pH 8.0, the rapid oxidation of Fe(II) as well as the rapid formation of Fe (oxyhydr)oxides facilitate a rapid removal of dissolved As(III) before its further oxidation to As(V).

Formation of iron (hydr)oxides during the abiotic oxidation of Fe(II) in the presence of arsenate

Abiotic oxidation of Fe(II) is a common pathway in the formation of Fe (hydr)oxides under natural conditions, however, little is known regarding the presence of arsenate on this process. In hence, the effect of arsenate on the precipitation of Fe (hydr)oxides during the oxidation of Fe(II) is investigated. Formation of arsenic-containing Fe (hydr)oxides is constrained by pH and molar ratios of As:Fe during the oxidation Fe(II). At pH 6.0, arsenate inhibits the formation of lepidocrocite and goethite, while favors the formation of ferric arsenate with the increasing As:Fe ratio. At pH 7.0, arsenate promotes the formation of hollow-structured Fe (hydr)oxides containing arsenate, as the As:Fe ratio reaches 0.07. Arsenate effectively inhibits the formation of magnetite at pH 8.0 even at As:Fe ratio of 0.01, while favors the formation of lepidocrocite and green rust, which can be latterly degenerated and replaced by ferric arsenate with the increasing As:Fe ratio. This study indicates that arsenate and low pH value favor the slow growth of dense-structured Fe (hydr)oxides like spherical ferric arsenate. With the rapid oxidation rate of Fe(II) at high pH, ferric (hydr)oxides prefer to precipitate in the formation of loose-structured Fe (hydr)oxides like lepidocrocite and green rust.

Reductive dissolution of ferrihydrite with the release of As(V) in the presence of dissolved S(-II)

In this study, reductive dissolution of As(V)-ferrihydrite and the mobilization of As(V) in the presence of S(-II) were investigated under anoxic conditions. Mobilization of As(V) strongly depended on the S(-II):Fe ratio and the amount of As(V) loading on ferrihydrite. High S(-II):Fe ratio caused a more complete dissolution of ferrihydrite and a large fraction of As(V) could be released into solution. The percentages of the released As(V) were 2.5% and 7.5% at S(-II):Fe ratios of 0.240 and 24.0, respectively, at pH 6.1, while the released As(V) were 5.5%, 16.3% at pH 8.0 under similar conditions. As(V) loading showed a negative effect on the release of arsenate, with smaller fraction of arsenate released into solution when more As (V) adsorbed on ferrihydrite. After 43 h, 14.1%, 5.5%, 1.6% and 0.7% of As(V) were released as for 10, 20, 50 and 100 mg L(-1) of As(V) loading, respectively, at pH 8.0. During the dissolution, secondary minerals such as goethite, magnetite and FeS were detected and played different roles in the mobilization of As(V). The released As(V) was mainly repartitioned on the residual ferrihydrite, the newly-formed goethite and magnetite but not FeS.

Mobilization and re-adsorption of arsenate on ferrihydrite and hematite in the presence of oxalate

In this study, mobilization and re-adsorption of arsenate on 2-line ferrihydrite and hematite in the presence of oxalate was investigated. Our results showed that arsenate could be mobilized during the dissolution of ferrihydrite and hematite. After reaching the maximum values, the released arsenate could re-adsorb on the residual ferrihydrite, whereas such an observation was not significant in hematite system. More reactive sites exposed during the dissolution of ferrihydrite could contribute to the re-adsorption of the released arsenate at pH 3.0, while the insignificant re-adsorption of arsenate on hematite could be explained by the inhibitory adsorption effect of oxalate on arsenate. Although dissolution rates of iron oxides decreased with the increase of arsenate on both ferrihydrite and hematite, dissolution rate was mainly determined by the reactivity of iron oxides, and ferrihydrite showed a higher reactivity than hematite in the presence of oxalate. Mathematic model proposed in our study further indicated that arsenate loading showed a more significant effect on arsenate mobilization in hematite system, while it was more effective in arsenate re-adsorption in ferrihydrite system.

Adsorptive removal of dibenzothiophene from model fuels over one-pot synthesized PTA@MIL-101(Cr) hybrid material

Hybrid nanomaterials comprising phosphotungstic acid (PTA) and MIL-101(Cr) were prepared through one-pot synthesis and post-modification methods and then were used as adsorbents of dibenzothiophene (DBT) from simulated diesel fuels. Samples obtained by different ways (encapsulation and impregnation) were characterized by nitrogen adsorption, transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR) and series of adsorption experiments. The equilibrium adsorption capacities of PTA@MIL-101(Cr) illustrated that the direct introduction of PTA into MIL-101(Cr) during synthesis resulted in a 10.7% increase compared with MIL-101(Cr). However, porous hybrid adsorbent PTA/MIL-101(Cr) prepared via post-modification method exhibited lower adsorption capacity than virgin MIL-101(Cr). The theoretical maximum adsorption capacity (Q0) of PTA@MIL-101(Cr) is 136.5mg S/g adsorbent, 4.2 times of MIL-101(Cr). Even in competitive adsorption between aromatic compounds, which possess strong affinity with MOFs, and DBT, PTA@MIL-101(Cr) and MIL-101(Cr) remained their effectiveness in removal of DBT in the system. Based on these results, it can be presumed that MIL-101(Cr), modified properly, can be used as a promising adsorbent for eliminating aromatics and S-compounds in commercial fuels simultaneously.

Abiotic oxidation of Mn(II) induced oxidation and mobilization of As(III) in the presence of magnetite and hematite

Manganese (hydr)oxides are powerful oxidants mediating the transformation of As(III) to As(V) under natural conditions, however, the presence of Mn(II) on the oxidation of As(III) in the pH range of 7.0-9.0 has not been reported so far. In this study, abiotic oxidation of Mn(II) to amorphous Mn(III, IV) (hydr)oxides (MnOx) on magnetite and hematite was confirmed, and the impact of newly formed MnOx on the fate of As(III) was investigated. With the addition of Mn(II) into As(III)-preloaded systems, the dissolved and the adsorbed As(III) was oxidized to As(V) at high pH, and Mn(II) mobilized the adsorbed As(III) and As(V) in hematite system. High production of dissolved As(V) and significant mobilization of As(III) were even more significant in hematite suspension (total As was 18.96 mgL(-1) after 60 h at pH 8.62) with simultaneous addition of Mn(II) and As(III), while magnetite showed a higher capacity for the retention of As(III) and As(V). It could therefore be deduced that the newly formed MnOx on iron oxides could oxidize the dissolved and the adsorbed As(III) to As(V). In addition, the MnOx formed at high pH would take up the sorption sites previously occupied by the adsorbed As(III), and then mobilized a fraction of the adsorbed As(III) into solution. The present study reveals that MnOx formed via abiotic oxidation on iron oxides plays an important role in the oxidation and mobilization of both dissolved and adsorbed As(III) in aquatic environment.

Effects of Mn(II) on the sorption and mobilization of As(V) in the presence of hematite

In this study, the effects of Mn(II) on the sorption and mobilization of As(V) by synthetic hematite were investigated. Our results showed that As(V) removal by hematite was evidently dependent on pH, and simultaneous addition of Mn(II) and As(V) into hematite suspension resulted in more removal of As(V) via electrostatic attraction at pH 4.0, 7.0 and 8.3. However, in Mn(II) pre-loaded system, the removal percentages of As(V) at pH 8.3 decreased by 17.0%, 20.7% and 26.7% after 24h at the aging time of 2, 12 and 36 h, respectively. The concentrations of the released As(V) after the addition of 1mM Mn(II) were 23.6, 12.9 and 7.0 μM at pH 8.5 in 2, 3 and 4 g L(-1) hematite suspension, respectively. But Ca(2+) did not show such an effect under similar experimental conditions. Abiotic oxidation of Mn(II) on hematite played an important role in As(V) mobilization. The growing thin layer of Mn(III, IV) (hydr)oxides (MnO(x)) formed on hematite would take up the sorption sites pre-occupied by As(V) and resulted in the release of the adsorbed As(V) back into solution. This study enriched our understanding on As(V) fate in the coexistence of iron oxides and Mn(II).