Modulation of Interfacial Characteristics of Copper Electrode by Electrodeposited Cu@Ti for High-Performance Anode-Free Zinc Ion Batteries.

Preparation of the NC-Cu@Ti electrode involved electrochemical deposition of nanocrystalline copper on the surface of titanium foil using a constant potential method, intended for high stability anode-free zinc ion battery (ZIB) anode material applications. This paper examines the effect of Cu2+ concentration in the electrodeposition solution on the structure and morphology of copper crystals on the NC-Cu@Ti electrode surface. The study also assesses how the interfacial properties of the NC-Cu@Ti electrode affect the process of anodic zinc deposition without anodic ZIBs. Our data suggest that with a voltage setting of -0.95 V and a copper ion concentration of 0.5 M in the solution, the deposition rate of copper crystals on the NC-Cu@Ti-0.5 electrode remains consistent. The resultant crystal phase surface appears smooth with a fine grain size. The NC-Cu@Ti-0.5 electrodes have increased hydrogen potentials and superior corrosion resistance; noting zinc nucleation sites at a mere 21.4 mV, it can provide stable electrochemical conditions for the zinc deposition interface of ZIBs and accelerate the process of zinc desolvation and nucleation. The constructed Zn//NC-Cu@Ti-0.5 asymmetric cell displays swift zinc deposition/stripping kinetics, elevated Coulombic efficiency, and prolonged stability (maintaining nearly 99% after 200 cycles). This performance significantly extends the service life relative to the Zn//Zn symmetric cell, which operates stably for 400 h at 1 mA/cm2. Moreover, the NC-Cu@Ti-0.5//MnO2 ZIBs offer enhanced conductivity and magnification performance to the pure zinc anode ZIBs. This study presents a novel approach for the low-cost and rapid preparation of anode materials for high-performance free-anode ZIBs.

The role of an amphiphilic helix and transmembrane region in the efficient acylation of the M2 protein from influenza virus.

Protein palmitoylation, a cellular process occurring at the membrane-cytosol interface, is orchestrated by members of the DHHC enzyme family and plays a pivotal role in regulating various cellular functions. The M2 protein of the influenza virus, which is acylated at a membrane-near amphiphilic helix serves as a model for studying the intricate signals governing acylation and its interaction with the cognate enzyme, DHHC20. We investigate it here using both experimental and computational assays. We report that altering the biophysical properties of the amphiphilic helix, particularly by shortening or disrupting it, results in a substantial reduction in M2 palmitoylation, but does not entirely abolish the process. Intriguingly, DHHC20 exhibits an augmented affinity for some M2 mutants compared to the wildtype M2. Molecular dynamics simulations unveil interactions between amino acids of the helix and the catalytically significant DHHC and TTXE motifs of DHHC20. Our findings suggest that the binding of M2 to DHHC20, while not highly specific, is mediated by requisite contacts, possibly instigating the transfer of fatty acids. A comprehensive comprehension of protein palmitoylation mechanisms is imperative for the development of DHHC-specific inhibitors, holding promise for the treatment of diverse human diseases.

Palmitoylation of the hemagglutinin of influenza B virus by ER-localized DHHC enzymes 1, 2, 4, and 6 is required for efficient virus replication.

IMPORTANCE: Influenza viruses are a public health concern since they cause seasonal outbreaks and occasionally pandemics. Our study investigates the importance of a protein modification called "palmitoylation" in the replication of influenza B virus. Palmitoylation involves attaching fatty acids to the viral protein hemagglutinin and has previously been studied for influenza A virus. We found that this modification is important for the influenza B virus to replicate, as mutating the sites where palmitate is attached prevented the virus from generating viable particles. Our experiments also showed that this modification occurs in the endoplasmic reticulum. We identified the specific enzymes responsible for this modification, which are different from those involved in palmitoylation of HA of influenza A virus. Overall, our research illuminates the similarities and differences in fatty acid attachment to HA of influenza A and B viruses and identifies the responsible enzymes, which might be promising targets for anti-viral therapy.

Photoelectrocatalytic modification of nanofiltration membranes with SrF2/Ti3C2Tx to simultaneously enhance heavy metal ions rejection and permeability.

Heavy metal pollution can significantly harm water systems and human health. Combining photoelectrocatalytic (PEC) and nanofiltration (NF) membrane separation technologies can effectively remove heavy metal ions from wastewater. In this study, a water bath method was used to form SrF2/Ti3C2Tx (ST) nanoparticles on the surface of polyvinylidene fluoride (PVDF) membranes and an additional polyamide (PA) functional layer was formed at the interface by crosslinking. ST@PA composite NF membranes (STPP) with good photocatalytic performance were obtained. The separation and catalytic properties of the STPP membranes were controlled by the ST content, which modifies the surface structure and properties of the membranes. The membrane with optimal ST crosslinking exhibited a water contact angle of 50.8°, pure water flux of 24.6 L·m-2·h-1·bar-1, and rejection rates of Mn2+, Ni2+, Cu2+, and Zn2+ of 98.8%, 95.3%, 95.7%, and 97.3%, respectively, under PEC-assisted separation with visible light illumination from a Xe lamp (300 W) and an applied voltage (2 V). The STPP membranes showed improved rejection rates of heavy metal ions under PEC-assisted operation. The mechanism for the improved membrane performance under PEC conditions was preliminarily clarified considering the relationship between the photocatalytic and filtration properties of STPP membranes along with the influence of light irradiation and an external voltage on the heavy metal ions. The generation of electrons, holes, superoxide radicals, and hydroxyl radicals during membrane operation enhances the rejection rates of heavy metal ions. Based on these results, STPP membranes are considered a promising technology for industrial applications in heavy metal removal.

Difference in oral microbiota composition between patients with stage 5 chronic kidney disease on hemodialysis and healthy controls.

Owing to the symbiotic relationship between the microbiota and the human body, the microbiome is considered a "second human genome". Microorganisms are inextricably associated with human diseases and can affect the host phenotype. In the present study, 25 female patients with stage 5 chronic kidney disease (CKD5) undergoing hemodialysis in our hospital and 25 healthy subjects were recruited. The structure of the oral microbiota of the study participants was analyzed using the MiSeq PE300 sequencing platform and high-throughput 16S rDNA sequencing. The microbiota was compared between the groups using QIIME and the stats package in R. In total, 1,336 operational taxonomic units (OTUs) were obtained, and the relative frequencies of 450 OTUs differed significantly between the two groups (P < 0.05), indicating that the samples were rich in OTUs. A comparison of ß-diversity indicated a significant difference in the microbial community structure between the two groups (P < 0.05). These results indicated that the biological diversity of the oral microbiota was highly correlated with CKD5. In this experiment, 189 genera, with significant differences in abundance between the groups (P < 0.05), were found. Furthermore, differences in the structure of the oral microbiota were observed between the groups at the phylum, class, order, family, and genus levels. Collectively, an imbalance in the oral microbiota may accelerate the progression of CKD and cause additional complications.

Regulated synthesis of Zr-metal-organic frameworks with variable hole size and its influence on the performance of novel MOF-based heterogeneous amino acid-thiourea catalysts.

We present an efficient and easy synthesis method for incorporating organocatalytic moieties into Zr-metal organic frameworks (Zr-MOFs). The catalytic activity and selectivity of the new chiral catalysts were improved by adjusting the aperture of the MOF cavities. The hole size of the Zr-MOF was modulated by adding acid and replacing bridge ligands during synthesis. The difunctional chiral units of amino acid-thiourea are anchored onto the Zr-MOF by a mild synthesis method from an isothiocyanate intermediate which could effectively avoid the racemization of chiral moieties in the synthesis process. By means of specific surface area measurement (BET), scanning electron microscopy (SEM) and powder X-ray Diffraction (PXRD), it was confirmed that Zr-MOFs with different pore sizes were synthesized without breaking the basic octahedral structure of the MOF. Finally, good yields (up to 83%) and ee values (up to 73%) were achieved with the new heterogeneous catalysts in 48 hours for the aldol reaction of 4-nitrobenzaldehyde with acetone. By contrast, using the catalyst support without modulating the synthesis, the yield (30%) and the ee-value (26%) were both low. Experiments have confirmed the important influence on the reaction selectivity of providing a suitable reaction environment by controlling the aperture of MOF cavities.

Emerging viruses: Cross-species transmission of coronaviruses, filoviruses, henipaviruses, and rotaviruses from bats.

Emerging infectious diseases, especially if caused by bat-borne viruses, significantly affect public health and the global economy. There is an urgent need to understand the mechanism of interspecies transmission, particularly to humans. Viral genetics; host factors, including polymorphisms in the receptors; and ecological, environmental, and population dynamics are major parameters to consider. Here, we describe the taxonomy, geographic distribution, and unique traits of bats associated with their importance as virus reservoirs. Then, we summarize the origin, intermediate hosts, and the current understanding of interspecies transmission of Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), SARS-CoV-2, Nipah, Hendra, Ebola, Marburg virus, and rotaviruses. Finally, the molecular interactions of viral surface proteins with host cell receptors are examined, and a comparison of these interactions in humans, intermediate hosts, and bats is conducted. This uncovers adaptive mutations in virus spike protein that facilitate cross-species transmission and risk factors associated with the emergence of novel viruses from bats.

Analysis of a Family with Brugada Syndrome and Sudden Cardiac Death Caused by a Novel Mutation of SCN5A.

Background: Brugada syndrome is a hereditary cardiac disease associated with mutations in ion channel genes. The clinical features include ventricular fibrillation, syncope, and sudden cardiac death. A family with Brugada syndrome with sudden cardiac death was analyzed to locate the associated mutation in the SCN5A gene. Methods and Results: Three generations of a Han Chinese family with Brugada syndrome were recruited in the study; their clinical phenotype data were collected and DNA samples extracted from the peripheral blood. Next-generation sequencing was carried out in the proband, and candidate genes and mutations were screened using the full exon capture technique. The family members who participated in the survey were tested for possible mutations using Sanger sequencing. Six family members were diagnosed with Brugada syndrome, including four asymptomatic patients. A newly discovered heterozygous mutation in the proband was located in exon 25 of SCN5A (NM_000335.5) at c.4313dup(p.Trp1439ValfsTer32). Among the surviving family members, only those with a Brugada wave on their electrocardiogram carried the c.4313dup(p.Trp1439ValfsTer32) variant. Bioinformatics prediction revealed that the frameshift of the c.4313dup (p.Trp1439ValfsTer32) mutant led to a coding change of 32 amino acids, followed by a stop codon, resulting in a truncated protein product. Conclusion: The newly discovered mutation site c.4313dup(p.Trp1439ValfsTer32) in exon 25 of SCN5A may be the molecular genetic basis of the family with Brugada syndrome.

Rare Cases of Bronchial Aneurysm and Comparison of Interventional Embolization in the Treatment of True Bronchial Aneurysm and Pseudobronchial Aneurysm.

Background: Bronchial artery aneurysm (BAA) is a rare disease. Rupture of BAA can lead to life-threatening hemoptysis, and once diagnosed, treatment is needed regardless of symptoms. Transcatheter artery embolization is the first choice of treatment because it is minimally invasive and effective. This study aimed to retrospectively compare the embolization treatment of a case of true BAA and that of a pseudobranchial aneurysm and explore the choice of embolization method for BAA with short neck or no neck. Materials and Methods: Embolization treatment and imaging characteristics of one case of true BAA and one case of pseudobronchial aneurysm admitted to our hospital were analyzed retrospectively. Embolization methods and therapeutic effects of two cases of BAAs were compared. Results: Case 1 was that of an intact true BAA inside the mediastinum located at the opening of the bronchial artery. The distal end of the aneurysm was embolized, and tumor cavity was occluded. No recurrence of BAA was found after the operation. Case 2 was that of a ruptured and hemorrhagic pseudobronchial aneurysm of the mediastinum. Coil embolization combined with covered stent graft exclusion of the thoracic aorta were performed, and the left bronchial artery and BAA were almost occluded. Nine months postoperatively, the mediastinal hematoma was almost completely absorbed. Conclusion: Endovascular embolization has become the most commonly used for the treatment of BAA. Different methods should be selected according to the location and nature of the aneurysm.

Core-shell Fe3O4@SnO2 nanochains toward the application of radar-infrared-visible compatible stealth.

Multiband-compatible stealth materials play an increasingly crucial role in the field of modern military defence because they can enable the targeted objects to dodge advance detection technologies. In this study, chain-like Fe3O4@poly(ethyleneglycol dimethacrylate-co-methacrylic acid) nanocomposites were constructed as precursors through the magnetic field-induced distillation precipitation polymerisation. Then, the liquid-phase seed-mediated growth method, together with subsequent calcination, was applied to introduce SnO2 shells and remove poly(ethyleneglycol dimethacrylate-co-methacrylic acid) shells, which led to the successful preparation of innovative core-shell Fe3O4@SnO2 nanochains. The unique microstructure and appropriate components endowed nanochains with multiple functional applications. The minimum reflection loss value was approximately -39.4 dB (5.67 GHz), exhibiting excellent microwave absorption performance. The possible microwave absorption mechanisms involve interfacial polarisation, space charge polarisation, natural resonance, and multiple reflections and scatterings. The optimal infrared reflectivity reached 0.64, 0.51, and 0.37 in three atmospheric windows, indicating outstanding infrared stealth performance, which was attributed to the intense infrared reflection of SnO2 shells. Furthermore, three nanochains showed different colours (dark green, brick red, and bright orange), revealing selection absorption for visible light. This can be attributed to the combined effect of visible responses of SnO2 shells along with Bragg diffraction from the periodic arrangement of Fe3O4 particles in a single nanochain. Thus, core-shell Fe3O4@SnO2 nanochains can be considered as promising radar-infrared-visible compatible stealth materials. This discovery opens a new means to exploit multiband-compatible stealth materials.

S-Acylation of Proteins of Coronavirus and Influenza Virus: Conservation of Acylation Sites in Animal Viruses and DHHC Acyltransferases in Their Animal Reservoirs.

Recent pandemics of zoonotic origin were caused by members of coronavirus (CoV) and influenza A (Flu A) viruses. Their glycoproteins (S in CoV, HA in Flu A) and ion channels (E in CoV, M2 in Flu A) are S-acylated. We show that viruses of all genera and from all hosts contain clusters of acylated cysteines in HA, S and E, consistent with the essential function of the modification. In contrast, some Flu viruses lost the acylated cysteine in M2 during evolution, suggesting that it does not affect viral fitness. Members of the DHHC family catalyze palmitoylation. Twenty-three DHHCs exist in humans, but the number varies between vertebrates. SARS-CoV-2 and Flu A proteins are acylated by an overlapping set of DHHCs in human cells. We show that these DHHC genes also exist in other virus hosts. Localization of amino acid substitutions in the 3D structure of DHHCs provided no evidence that their activity or substrate specificity is disturbed. We speculate that newly emerged CoVs or Flu viruses also depend on S-acylation for replication and will use the human DHHCs for that purpose. This feature makes these DHHCs attractive targets for pan-antiviral drugs.

Electro-membrane extraction of cadmium(II) by bis(2-ethylhexyl) phosphate/kerosene/polyvinyl chloride polymer inclusion membrane.

The development of the electroplating and battery industries has increased the environmental problems and the needs for resource recovery of Cd(II). In this study, the Electro-membrane extraction (EME) behaviour of Cd(II) was investigated by using polymer inclusion membrane with bis(2-ethylhexyl) phosphate as carrier and polyvinyl chloride as base polymer(PD-PIM) at 0-80 V. Results showed that the EME of Cd(II) by PD-PIM can be obtained in the feed phase with pH 3-8 and stripping phase of dilute acid. Voltage is the main factor to increase the mass transfer rate of Cd(II). The applied electric field reduced the mass transfer activation energy of Cd(II) by PD-PIM and weakened the mass transfer interference of Cd(II) on the background material of the feed phase. After using kerosene-stabilised PD-PIM for operation at pH5, 60 V for 120 h, Cd(II) in the 1 L solution reduced from 15 mg/L to 0.08 mg/L, and the enrichment factor was 9.79.

Study on stable mass transfer and enrichment of phenol by 1-octanol/kerosene/polyvinyl chloride polymer inclusion membrane.

A polymer inclusion membrane (PIM) that contains a polyvinyl chloride (PVC) polymer matrix and 1-octanol (OCT) as specific carrier (PO-PIM) was prepared to investigate the mass transfer behaviour of phenol in aqueous solutions. Results showed that the mass transfer behaviour of the PO-PIM for phenol conformed to the first-order kinetics. In addition, the mass transfer efficiency for phenol reached the maximum when the OCT content was 82.8 wt%. The mass transfer activation energy (Ea) was 14.46 kJ mol-1, which indicated that intramembranous diffusion was the main controlling factor in the mass transfer process. The introduction of hydrophobic additives, such as kerosene, liquid paraffin and vegetable oil, into the PO-PIM could remarkably improve its stability. In an aqueous solutions of phenol ranging from 0 mg L-1 to 9000 mg L-1, the initial flux (J0) of kerosene/PVC/OCT-PIM (KPO-PIM) was positively correlated with the initial concentration of phenol. For a stripping solution with a feed solution pH of 2.0 and a sodium hydroxide concentration of 0.1 mol L-1, the maximum permeability coefficient during stable mass transfer reached 12.55 µm s-1. At a mass transfer area of 3.14 cm2, an enrichment factor (EF) of 3.5 for 200 mg L-1 of phenolic aqueous solution was achieved within 48 h through KPO-PIM.

[Quantitative Analysis of Dominant Pollutants in Secondary Effluent via Dye Probe Technology].

The linear relationship between the concentration of either bovine serum albumin (BSA) or sodium alginate (SA) and the intensity of a resonance light scattering (RLS) spectrum was established by using Congo red and neutral red as the dye probes, respectively. Moreover, the linear relationship between the concentration of humic acids (HA) and UV absorbance was determined by using toluidine blue (TB) as the dye probe. The detection of concentration range and the pH value of three kinds of standard substances were optimized. The recovery rate of bi-and tri-element samples of the standard objects was investigated by means of the dye probe analysis method. The results show that, in the appropriate concentration range, the linear correlation coefficients between the concentration of BSA, HA, or SA and the intensity of its corresponding dye probe spectrum were all high, at 0.98. The recovery rates of the three kinds of standard objects in mixed samples were all greater than 95%, and the standard errors were all less than 0.11%. Based on qualitative analysis of the proteins, polysaccharides, and humic acids in the secondary water discharge samples of urban sewage obtained via UV and RLS spectra, the dominant pollutants were confirmed in the four kinds of secondary effluent. The relative deviations of the concentration of polysaccharides and proteins measured using the dye probe technique and the national standard method ranged were from 1.2% to 0.04%.

Analysis of mutations of two Gitelman syndrome family SLC12A3 genes and proposed treatments using Chinese medicine.

OBJECTIVE: To determine the gene location of two Gitelman syndrome (GS) family SLC12A3 genes and explore treatments using Chinese medicine (CM) prescriptions. METHODS: In order to locate the two GS mutations, samples were collected from 11 people from two different pedigrees for direct genetic sequencing and comparison of the 26 exons of SLC12A3. Furthermore, the change of serum potassium was monitored throughout the therapy and those two probands undertook a sequential superposition of Western medicine (including potassium, Panangin and potassium-sparing diuretics) with CM prescription based on Buyang Huanwu Decoction () and Sijunzi Decoction (). The treatment included three stages, oral potassium chloride for the first 2 weeks (stage 1), potassium-sparing diuretic and Panangin with potassium chloride for the next 2 weeks (stage 2), CM along with the medicine in stage 2 for the final 2 weeks (stage 3). RESULTS: The three mutations occurring in proband 1 from pedigree I were Thr60Met, 965-1_976del13ins12 (small indels mutation) and Ala122Ala (homozygous silent mutation). Likewise, three mutations, Asn359Lys, Thr382Met and Arg913Gln, appeared in the proband 2 from pedigree II. The serum potassium levels increasing from baseline to sequential stages were 1.63 mmol/L (baseline), 2.5 mmol/L (stage 1), 3.1 mmol/L (stage 2) and 3.9 mmol/L (stage 3) in the proband 1, and 2.8 mmol/L (baseline), 3.1 mmol/L (stage 1), 3.5 mmol/L (stage 2) and 4.3 mmol/L (stage 3) in the proband 2, respectively. The symptoms (numbness of limbs, weakness, palpitations, etc.) of both probands were all alleviated. CONCLUSIONS: The mutations of both GS pedigrees can be defined as compound heterozygous mutations, most of which are known as missense mutations. Applying CM could be an appropriate choice for future intervention of GS.

The Construction of Unsmooth Pulse Images in Traditional Chinese Medicine Based on Wave Intensity Technology.

Unsmooth pulse is one of the most important pulses in TCM diagnostics. We constructed the wave intensity (WI) images of unsmooth pulse based on the pressure wave (P), flow velocity wave (U), and WI [(dP/dt)(dU/dt)] by ALOKA Prosound α 10 Color Doppler. The characteristic of Cunkou normal pulse could be summarized as follows: compared to Renying pulse, its W1 amplitude is smaller and NA wave is more obvious, while the W2 wave is indistinct or even invisible, and the R-1st is longer than that of Renying pulse. The principal U wave of Renying pulse looks like "Λ" shape, while it looks like an arched blunt "∩" shape in Cunkou pulse, and the amplitude of U wave in Cunkou pulse is smaller. The direction of the principal U wave in Cunkou unsmooth pulse is up, which shows hoof boots "h" shape with high amplitude and a significant notch on declined branch; the amplitude of predicrotic wave in unsmooth pulse P wave is significantly higher, which could be even higher than that of h1, resulting in early appearance of h3 or integrating with h1, which forms a wide and blunt peak. Unsmooth pulse shows poorer vascular elasticity and greater vascular stiffness.

Enhanced gypsum scaling by organic fouling layer on nanofiltration membrane: Characteristics and mechanisms.

To investigate how the characteristics of pregenerated organic fouling layers on nanofiltration (NF) membranes influence the subsequent gypsum scaling behavior, filtration experiments with gypsum were carried out with organic-fouled poly(piperazineamide) NF membranes. Organic fouling layer on membrane was induced by bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA), respectively. The morphology and components of the scalants, the role of Ca(2+) adsorption on the organic fouling layer during gypsum crystallization, and the interaction forces of gypsum on the membrane surface were investigated. The results indicated that SA- and HA-fouled membranes had higher surface crystallization tendency along with more severe flux decline during gypsum scaling than BSA-fouled and virgin membranes because HA and SA macromolecules acted as nuclei for crystallization. Based on the analyses of Ca(2+) adsorption onto organic adlayers and adhesion forces, it was found that the flux decline rate and extent in the gypsum scaling experiment was positively related to the Ca(2+)-binding capacity of the organic matter. Although the dominant gypsum scaling mechanism was affected by coupling physicochemical effects, the controlling factors varied among foulants. Nevertheless, the carboxyl density of organic matter played an important role in determining surface crystallization on organic-fouled membrane.

[Interfacial Property of Amphiphilic Copolymer Blending PVDF UF Membrane and Protein Anti-fouling].

The phase transformation kinetic process of amphiphilic copolymer polyoxyethylene/polyoxypropylene/polyoxyethylene[PEO-PPO-PEO(F127)] blending polyvinylidene fluoride (PVDF) casting solution in an aqueous gel bath was investigated. The influences of F127 content on the PEO enrichment rate of PVDF membrane surface, membrane morphology and structural parameters were investigated by a total reflection fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscope (SEM), atomic force microscopy (AFM) and other analytical techniques. F127/PVDF blending membrane fouling behavior of bovine serum albumin (BSA) was evaluated by the static adsorption capacity, normalized filtration decay rate and membrane fouling resistance model. The results showed that the membrane delayed phase separation process increased, the membrane surface, internal pore size and porosity increased and the surface roughness increased with increasing F127 addition, and the increment of PEO enrichment rate on the membrane surface became stable when the F127 content reached 15%. F127 blending membranes with F127 contents ranging from 15% to 25% had a higher flux and BSA rejection, lower static adsorption capacity, slower flux decay rate, lower irreversible fouling index and smaller pore blocking resistance and cake layer resistance distribution coefficient, which showed a good anti-fouling property.

Fouling behaviour of membranes with different characteristics by urban wastewater secondary effluent.

Fouling behaviours and antifouling properties of polyvinylidene fluoride (PVDF) ultrafiltration membranes blending with polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP) and polymethyl methacrylate (PMMA) had been investigated using the secondary effluent as the filtration medium. The results demonstrated that the antifouling properties of membranes using PVA and PVP as the additives were generally stronger than those using PMMA. Additives PVA and PVP could effectively improve the structural property and hydrophilicity of the membrane and result in an outstanding antifouling property. A dense membrane surface could prevent low molecular foulants from entering into the membrane pores, depositing on the membrane with a loose spongy layer and penetrating into the internal macropore structure. The not fully generated internal macropores on the membrane surface were trend to be plugged, which resulted in serious flux decay and the membrane fouling was irreversible. Filtration cake formed on the membrane due to concentration polarization, which caused membrane flux decline and high flux recovery after cleaning.

[Adhesion Force Analysis of Protein Fouling of PVDF Ultrafiltration Membrane Using Atomic Force Microscope].

To determine the fouling behavior of bovine serum albumin (BSA) on differet hydropniic PVDF ultrafiltration membrane over a range of pH, atomic force microscopy (AFM) and self-made colloidal probes were used to detect the microscopic adhesion forces of membrane-BSA and BSA-BSA, respectively. The results showed a positive correlation between the flux decline extent and the membrane-foulant adhesion force in the initial filtration stage, whereas the foulant-foulant interaction force was closely related to the membrane fouling in the later filtration stage. Moreover, the membrane-BSA adhesion interaction was stronger than the BSA-BSA adhesion interaction, which indicated that the fouling was mainly caused by the adhesion interaction between membrane and foulant. At the same pH, the adhesion force between PA membrane-BSA was smaller than that of PP membrane-BSA, illustrating the more hydrophilic the membrane was, the better the antifouling ability it had. The adhesion force between BSA-BSA fouled PA membrane was similar to that between BSA-BSA fouled PP membrane. These results confirmed that elimination of the membrane-BSA adhesion force is important to control the protein fouling of membranes.