Synthesis and Characterization of Covalent Triazine Framework CTF-1@Polysulfone Mixed Matrix Membranes and Their Gas Separation Studies

Covalent triazine framework CTF-1 and polysulfone (PSF) are used to form mixed-matrix membranes (MMMs) with 8, 16, and 24 wt% of the porous filler material CTF-1. Studies on permeability and selectivity are carried out concerning the gases O2, N2, CO2, and CH4. CO2 permeability of the synthesized MMMs increases by 5.4 Barrer in comparison to the pure PSF membrane. The selectivity remains unchanged for O2/N2 and CO2/CH4 but was found to be increased for CO2/N2. Further, comparisons to theoretical models for permeability prediction yield a permeability for CTF-1 which is about six times higher than the permeability of PSF. The inverse of the sum of the free fractional volumes (FFV) of the polymer and the filler correlate linearly to the logarithm of the permeabilities of the gases which conversely indicates that the porosity of the filler contributes to the gas transport through the membrane

Photocatalytic CO₂ Reduction Based on a Re(I)-Integrated Conjugated Microporous Polymer: Role of a Sacrificial Electron Donor in Product Selectivity and Efficiency

One of the major challenges in photocatalytic CO2 reduction is achieving control over the selective formation of a single product while maintaining a high conversion efficiency. Here, we report the synthesis and characterization of a conjugated microporous polymer (TEB-BPY) formed by C–C coupling between 1,3,5-triethynylbenzene and 5,5′-dibromo-2,2′-bipyridine. Further, [Re(CO)5Cl] covalently integrated with the polymer, and the resulting metalated Re@TEB-BPY polymer was used as a catalyst for the visible-light-driven CO2 reduction. Re@TEB-BPY displays photoconversion of CO2 to CO with a production rate of 91.7 μmol g–1 h–1 and a selectivity of ∼68% in the presence of triethylamine (TEA) as the sole sacrificial electron donor. Interestingly, CH4 is produced as a major product instead of CO when CO2 reduction was performed using 1-benzyl-1,4-dihydronicotinamide (BNAH) as a sacrificial electron donor in the presence of TEA as a base. In this reaction, Re@TEB-BPY produces CH4 as the major product with a rate of 2.05 mmol g–1 h–1 (selectivity of ∼96% and apparent quantum efficiency of 0.22%). From an in situ diffuse reflectance FTIR spectroscopy (DRIFTS) study together with DFT calculations, a possible catalytic cycle for CO2 reduction to CO or CH4 is constructed. Theoretical calculations along with control experiments further reveal that TEA acts mainly as a base in the presence of BNAH to suppress the back electron transfer process, resulting in enhanced photocatalytic activity

Covalent Triazine Frameworks Based on the First Pseudo-Octahedral Hexanitrile Monomer via Nitrile Trimerization: Synthesis, Porosity, and CO2 Gas Sorption Properties

Herein, we report the first synthesis of covalent triazine-based frameworks (CTFs) based on a hexanitrile monomer, namely the novel pseudo-octahedral hexanitrile 1,4-bis(tris(4′-cyano-phenyl)methyl)benzene 1 using both ionothermal reaction conditions with ZnCl2 at 400 °C and the milder reaction conditions with the strong Brønsted acid trifluoromethanesulfonic acid (TFMS) at room temperature. Additionally, the hexanitrile was combined with different di-, tri-, and tetranitriles as a second linker based on recent work of mixed-linker CTFs, which showed enhanced carbon dioxide captures. The obtained framework structures were characterized via infrared (IR) spectroscopy, elemental analysis, scanning electron microscopy (SEM), and gas sorption measurements. Nitrogen adsorption measurements were performed at 77 K to determine the Brunauer-Emmett-Teller (BET) surface areas range from 493 m2/g to 1728 m2/g (p/p0 = 0.01–0.05). As expected, the framework CTF-hex6 synthesized from 1 with ZnCl2 possesses the highest surface area for nitrogen adsorption. On the other hand, the mixed framework structure CTF-hex4 formed from the hexanitrile 1 and 1,3,5 tricyanobenzene (4) shows the highest uptake of carbon dioxide and methane of 76.4 cm3/g and 26.6 cm3/g, respectively, at 273 K

A homochiral vanadium-salen based cadmium bpdc MOF with permanent porosity as an asymmetric catalyst in solvent-free cyanosilylation

A homochiral vanadium-salen based MOF with the pcu topology is constructed via in situ synthesis under solvothermal conditions. The synthesized MOF exhibits BET surface areas of 574 m(2) g(-1), showing the highest H-2 adsorption capacity (1.05 wt% at 77 K, 1 bar) and the highest CO2 uptake (51 cm(3) g(-1) at 273 K, 1 bar) for currently known salen-based MOFs. This framework shows excellent performance as an asymmetric catalyst in solvent-free cyanosilylation

A photoluminescent covalent triazine framework: CO2 adsorption, light-driven hydrogen evolution and sensing of nitroaromatics

A highly photoluminescent (PL) porous covalent triazine-based framework (PCTF-8) is synthesized from tetra(4-cyanophenyl) ethylene by using trifluoromethanesulfonic acid as the catalyst at room temperature. Due to triazine units in the framework, the PCTF-8 exhibits excellent thermal stability (>400 degrees C). The Brunauer-Emmett-Teller (BET) specific surface area of PCTF-8 is 625 m(2) g(-1) which is lower than the one obtained from the synthesis under Lewis acid conditions (ZnCl2). At 1 bar and 273 K, the PCTF-8 adsorbs a significant amount of CO2 (56 cm(3) g(-1)) and CH4 (17 cm(3) g(-1)) which is highly comparable to nanoporous 1,3,5-triazine frameworks (NOP-1-6, 29-56 cm(3) g(-1)). This nitrogen rich framework exhibits good ideal selectivity (61 : 1 (85% N-2 : 15% CO2) at 273 K, 1 bar). Thus, it can be used as a promising candidate for potential applications in post-combustion CO2 capture and sequestration technologies. In addition, photoluminescence properties as well as the sensing behaviour towards nitroaromatics have been demonstrated. The fluorescence emission intensity of PCTF-8 is quenched by ca. 71% in the presence of 2,4,6-trinitrophenol (TNP). From time-resolved studies, a static quenching behaviour was found. This high photoluminescence property is used for hydrogen evolving organic photocatalysis from water in the presence of a sacrificial electron donor and a cocatalyst

Twin outbreak of cholera in rural North Karnataka, India

Background & objectives: Successive outbreaks of acute watery diarrhoea occurred in Talikoti and Harnal, located in Bijapur District of the southern Indian s0 tate of Karnataka, in July and August 2012, respectively. These outbreaks were investigated to identify the aetiology and epidemiology. Methods: Information was collected from the local population and health centres. Stool and water samples were collected from the admitted patients and their drinking water sources. Standard microbiological and PCR techniques were employed for isolation and characterization of the pathogen. Results: While 101 people (0.38%) were affected in Talikoti, 200 (20.94%) were affected in Harnal which is a small remote village. All age groups were affected but no death occurred. While the outbreak was smaller, longer and apparently spread by person to person contact in Talikoti, it occurred as a single source flash outbreak at Harnal. A single clone of toxigenic Vibrio cholerae O1 Ogawa biotype El Tor was isolated from the two stool samples obtained from Talikoti and subsequently from three of five stool samples obtained from Harnal indicating village to village spread of the aetiological agent. Striking similarity in antibiotic resistance profiles of these isolates with a particular strain isolated from the city of Belgaum, 250 km away, in 2010, prompted tracking the lineage of the V. cholerae isolates by DNA fingerprinting. Random amplified polymorphic DNA (RAPD) fingerprinting assay helped confirm the origin of the incriminating strain to Belgaum. Interpretation & conclusions: Our study reported the first twin outbreak of cholera in two remote areas of Bijapur district, Karnataka, south India. It also indicated the need for immediate preparedness to deal with such emergencies

Linking Depressive and Anxiety Symptoms with Diet Quality of University Students: A Cross-Sectional Study during the COVID-19 Pandemic in India

Kundu S, Rejwana N, Al Banna MH, et al. Linking Depressive and Anxiety Symptoms with Diet Quality of University Students: A Cross-Sectional Study during the COVID-19 Pandemic in India. Healthcare. 2022;10(10): 1848.This study examines the association of depressive and anxiety symptoms with diet quality among university students while controlling for different demographic and other health and lifestyle factors. This cross-sectional study was carried out between April 2021 and June 2021 among a total of 440 (unweighted) university students. Diet quality was assessed using a 10-item mini-dietary assessment index tool. The depressive and anxiety symptoms of participants were measured using the validated Patient Health Questionnaire-9 (PHQ-9), and the Generalized Anxiety Disorder (GAD-7) scale, respectively. Multivariable logistic regression and mediation analyses were performed. In this study, 61.1% (95% CI: 56.6% to 65.7%) of university students’ diet quality was good during the COVID-19 pandemic. Being a post-graduate student, an urban resident, having no depressive (AOR = 2.15, 95% CI: 1.20 to 3.84) and anxiety symptoms (AOR = 1.96, 95% CI: 1.07 to 3.59), no changes or improvement in appetite, and no changes in sleep duration were significantly associated with good diet quality among our study participants. Depressive and anxiety symptoms during COVID-19 had a significant effect on the diet quality of university students. Future public health policies need to be focused on improving the mental health and well-being of students particularly during pandemic situations to enhance their diet quality

Optimization of green microwave-assisted extraction of essential oil from lemon (Citrus limon) leaves: Bioactive, antioxidant and antimicrobial potential

This research delves into the analysis of essential oil derived from Citrus limon leaves cultivated in the northern region of Bangladesh, focusing on their potential attributes. The essential oil was extracted employing a microwave-assisted gravity station without using solvent. Optimization was carried out in terms of time, temperature and power as a function of oil yield. The study revealed the highest oil yield of 2.5 % after 50 min at 110 °C, maintaining a microwave power of 300 watt. Twenty-four (24) phyto-components were identified by Gas Chromatogram- Mass Spectrometer (GC-MS) where d-Limonene (34.10660 %) was dominant compound. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to assess the antioxidant activity of essential oil. Notably, essential oil displayed superior DPPH radical scavenging activity (IC50 8.57 ppm) compared to butylated hydroxytoluene (BHT) (IC50 10.63 ppm), a common antioxidant standard. Furthermore, a variety of harmful microorganisms were used to evaluate the antimicrobial efficacy. The extracted essential oil exhibited the strongest antimicrobial effectiveness against bacteria Staphylococcus aureus (ZOI-27.50 mm, MIC-7.8 μL/mL) and the fungi Candida albicans (ZOI-32.83 mm, MIC-1.95 μL/mL). These findings demonstrate the Citrus limon leaves essential oil contains bioactive components with strong antioxidant and antimicrobial properties. The extracted essential oil holds significant potential for applications in the foods, pharmaceuticals and cosmetic industries