Polydopamine mediated self-cleaning of high-flux pH-responsive isoporous membranes for filtration applications

A major challenge in membrane filtration is fouling which reduces the membrane performance. The fouling is mainly due to the adhesion of foulants on the membrane surfaces. In this work, we studied the fouling behavior of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) isoporous membrane and the mussel inspired polydopamine/L-Cysteine isoporous zwitterionic membrane. The polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) isoporous membrane was fabricated via self-assembly and non-solvent induced phase separation.1 Subsequently, the isoporous membrane was modified through a mild mussel-inspired polydopamine (PDA) coating by retaining the isoporous morphology and water flux.2 Furthermore, zwitterionic L-Cysteine was anchored on the PDA layer coated membranes via Michael addition reaction at neutral pH and 50oC. The membranes were thoroughly characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and zeta potential measurements. The contact angle and dynamic scanning calorimetry (DSC) measurements were carried out to examine their hydrophilicity. The pH-responsive behaviour of the modified membrane remains unchanged and the antifouling ability after PDA/L-Cysteine functionalization was improved. The modified and unmodified isoporous membranes were tested using humic acid and natural organic matter contaminated solutions at 0.5 bar feed pressure. References Peinemann, K.-V.; Abetz, V.; Simon, P. F. W. Asymmetric Superstructure Formed in a Block Copolymer via Phase Separation. Nat. Mater. 2007, 6, 992–996. Lee, H.; Dellatore, S. M.; Miller, W. M.; Messersmith, P. B. Mussel-Inspired Surface Chemistry for Multifunctional Coatings. Science. 2007, 318, 426–430

Seroprevalence of Rubella IgG in Women of Reproductive Age Group in a Tertiary Care Teaching Hospital

Rubella is a highly contagious infection caused by the rubella virus. Mothers who develop rubella early in pregnancy have a 90% chance of transmitting the infection to their unborn babies. Adverse effects on the fetus include stillbirth and congenital rubella syndrome. Pregnant women are not regularly screened for rubella antibodies in government hospitals in Kerala. Therefore, to raise awareness of healthcare providers, it is necessary to collect epidemiological data on the seroprevalence of rubella in this vulnerable group. Several sociodemographic variables as potential predictors of immunity to rubella were also analyzed. A cross-sectional descriptive study was conducted at Govt TD Medical College in Alappuzha, Kerala, of 604 women of childbearing potential who attended the Out patient department of the Obstetrics and gynecology division for the year from June 2016 to June 2017. Rubella-specific IgG (Quantitative) ELISA was done on patients after obtaining informed consent and filling out a questionnaire through direct interview. The test sera were considered seropositive (>15 IU/ml), seronegative (<13 IU/ml), or intermediate (13 -15 IU/ml) as per the manufacturer’s instructions. Rubella seroprevalence in the study group was found to be 73.3%. Around 26.65% were nonimmune to rubella infection. About 27.4% of antenatal cases in the present study were susceptible to rubella. The primigravidae had lower seroprevalence(28.5%) than multigravidae. The percentage of seropositivity was found to increase with age. Our observations show that women of childbearing age are highly susceptible to rubella. High seroprevalence without regular childhood vaccination indicates continued infection transmission of the rubella virus in the community. Hence there is a need for proper sero surveillance in this group who has not been vaccinated, before conception to eradicate CRS and Rubella

CO2-Philic Thin Film Composite Membranes: Synthesis and Characterization of PAN-r-PEGMA Copolymer

In this work, we report the successful fabrication of CO2-philic polymer composite membranes using a polyacrylonitrile-r-poly(ethylene glycol) methyl ether methacrylate (PAN-r-PEGMA) copolymer. The series of PAN-r-PEGMA copolymers with various amounts of PEG content was synthesized by free radical polymerization in presence of AIBN initiator and the obtained copolymers were used for the fabrication of composite membranes. The synthesized copolymers show high molecular weights in the range of 44–56 kDa. We were able to fabricate thin film composite (TFC) membranes by dip coating procedure using PAN-r-PEGMA copolymers and the porous PAN support membrane. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied to analyze the surface morphology of the composite membranes. The microscopy analysis reveals the formation of the defect free skin selective layer of PAN-r-PEGMA copolymer over the porous PAN support membrane. Selective layer thickness of the composite membranes was in the range of 1.32–1.42 μm. The resulting composite membrane has CO2 a permeance of 1.37 × 10−1 m3/m2·h·bar and an ideal CO2/N2, selectivity of 65. The TFC membranes showed increasing ideal gas pair selectivities in the order CO2/N2 &gt; CO2/CH4 &gt; CO2/H2. In addition, the fabricated composite membranes were tested for long-term single gas permeation measurement and these membranes have remarkable stability, proving that they are good candidates for CO2 separation

Complexation-Induced Phase Separation: Preparation of Composite Membranes with a Nanometer-Thin Dense Skin Loaded with Metal Ions

We present the development of a facile phase-inversion method for forming asymmetric membranes with a precise high metal ion loading capacity in only the dense layer. The approach combines the use of macromolecule-metal intermolecular complexes to form the dense layer of asymmetric membranes with nonsolvent-induced phase separation to form the porous support. This allows the independent optimization of both the dense layer and porous support while maintaining the simplicity of a phase-inversion process. Moreover, it facilitates control over (i) the thickness of the dense layer throughout several orders of magnitude from less than 15 nm to more than 6 μm, (ii) the type and amount of metal ions loaded in the dense layer, (iii) the morphology of the membrane surface, and (iv) the porosity and structure of the support. This simple and scalable process provides a new platform for building multifunctional membranes with a high loading of well-dispersed metal ions in the dense layer

Clinical Study on Dosha-Based Combinations in Essential Hypertension

Hypertension (HT) is one of the most vital modifiable risk factors for coronary heart disease, stroke, congestive heart failure, chronic kidney disease, and peripheral vascular disease. Data from HT trials indicate that most subjects need combination therapy to achieve sufficient BP control and in only 50% of trials, this goal was achieved. Addressing the contributory factors is the need of the hour rather than controlling blood pressure (BP) level only. Here the Ayurvedic drugs are having a definite scope in the management. HT may be considered as tridoshaja vyadhi with Vatha dominance with affection of the rasa and raktha dhatus. Ayurgenomics is having a crucial role in explaining how drugs can be used more effectively by targeting them on individuals of particular Prakriti.. The unique method of administering the drug based on the prakriti and dosha in any clinical condition so as to enhance the effect is termed personalized medicine and based on the judgment that the doshahara drugs when added to vyadhihara drug enhances its efficacy potential. Sarpagandha was added with brihat panchamoola, trina panchamoola and triphala in Vatha, Pitta and Kapha groups respectively. Methodology: In the multicentric study, 50 subjects each of Vatha, Pitta and Kapha prakrithi, satisfying the diagnostic criteria were administered with the drug, 6 gm twice daily after food, as per the dosha status for 45 days with BP assessments on 0th day, 15th, 30th, 45th and 60th day. Repeated Measures ANOVA was done for analysis. Result: The mean score reduced throughout the assessments and was significant at 0.01% level indicating the influence on prakriti in the outcome

Rational design of mixed-matrix metal-organic framework membranes for molecular separations

International audienceConventional separation technologies to separate valuable commodities are energy intensive, consuming 15% of the worldwide energy. Mixed-matrix membranes, combining processable polymers and selective adsorbents, offer the potential to deploy adsorbent distinct separation properties into processable matrix. We report the rational design and construction of a highly efficient, mixed-matrix metal-organic framework membrane based on three interlocked criteria: (i) a fluorinated metal-organic framework, AlFFIVE-1-Ni, as a molecular sieve adsorbent that selectively enhances hydrogen sulfide and carbon dioxide diffusion while excluding methane; (ii) tailoring crystal morphology into nanosheets with maximally exposed (001) facets; and (iii) in-plane alignment of (001) nanosheets in polymer matrix and attainment of [001]-oriented membrane. The membrane demonstrated exceptionally high hydrogen sulfide and carbon dioxide separation from natural gas under practical working conditions. This approach offers great potential to translate other key adsorbents into processable matrix

Polyanionic pH-responsive polystyrene-b-poly(4-vinyl pyridine-N-oxide) isoporous membranes

Recently isoporous block copolymer (BCP) membranes obtained by non-solvent induced phase separation gained a lot of attention due to their highly ordered surface layer, high flux and superior separation properties. These polystyrene-b-poly-4-vinylpyridine (PS-b-P4VP) based membranes showed a strong flux dependence of pH; pores closed at low pH and opened at high pH. The pH-response could now be reversed by a simple post modification; pores are now opening at low pH and closing at high pH. The original membrane was transformed into a polyanionic pH responsive membrane in a one step chemical modification without affecting the isoporous surface morphology. A polystyrene-b-poly-4-vinylpyridine-N-oxide (PS-b-P4VPN-oxide) membrane is obtained by selective oxidation of the PS-b-P4VP membrane. The in situ generated peracid obtained by reacting acetic acid and hydrogen peroxide is employed for oxidation. Surprisingly not only the asymmetric membrane structure with the isoporous skin was retained, but also the mechanical and chemical membrane stability was improved significantly. The modified membranes are insoluble in solvents like DMF, NMP and DMSO. Two kinds of PS-b-P4VP based isoporous membranes are available now with reverse flux response to pH. This opens the door to new interesting charge based fractionations. [Display omitted] •Polyanionic pH-responsive isoporous block copolymer membranes were prepared.•The membranes were synthesized by a chemical post-modification of PS-b-P4VP membranes.•The membrane pores are opening at low pH and closing at high pH.•The post-modification improved the mechanical and chemical stability of the membranes