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Two-dimensional (2D) covalent organic frameworks (COFs) are composed of structurally precise, permanently porous, layered macromolecular sheets, which are traditionally synthesized as polycrystalline solids with crystalline domain lengths smaller than 100 nm. Here, we polymerize imine-linked 2D COFs as suspensions of faceted single crystals in as little as 5 min at moderate temperature and ambient pressure. Single crystals of two imine-linked 2D COFs were prepared, consisting of a rhombic 2D COF (

Herein, the aggregation manner of the mixture of polyvinyl alcohol (PVA) and tetradecyltrimethylammonium bromide (TTAB) was performed in polyols (glucose, maltose and galactose) media over 300.55–320.55 K temperatures range with 5 K interval through conductivity measurement method. The micelle formation of TTAB + PVA mixture was identified by the assessment of critical micelle concentration (CMC) from the plots of specific conductivity (κ) versus TTAB concentration. The degree of micelle ionization (α), the extent of bound counter ions (β) as well as thermodynamic properties ( Δ G m 0 ${\Delta}{G}_{m}^{0}$ , Δ H m 0 ${\Delta}{H}_{m}^{0}$ and Δ S m 0 ${\Delta}{S}_{m}^{0}$ ) of TTAB + PVA systems have been estimated. The CMC values reveal that the micelle formation of TTAB + PVA mixture experience an enhancement in the manifestation of polyols. The values of free energy of micellization ( Δ G m 0 ${\Delta}{G}_{m}^{0}$ ) are negative for the TTAB + PVA system in aqueous polyols media, suggesting a spontaneous aggregation phenomenon. The Δ H m 0 ${\Delta}{H}_{m}^{0}$ and Δ S m 0 ${\Delta}{S}_{m}^{0}$ values of TTAB + PVA systems direct that the PVA molecule interacts with TTAB through the exothermic, ion-dipole, and hydrophobic interactions. The thermodynamic properties of transfer were also determined for the move of TTAB + PVA mixture from H2O to water + polyols mixed solvents. The values of compensation temperature (T c) and intrinsic enthalpy gain ( Δ H m 0 , ∗ ${\Delta}{H}_{m}^{0,\ast }$ ) were evaluated and discussed for the studied system.

WHO is searching most active antibiotics due to the bacterial resistance problem. The activities of the racemic antibiotics may be augment by preparing optically active antibiotics by the chiral separation. Chiral separation of potential antibiotics such as cefotaxime and ofloxacin was studied using amylose-based packing chiral stationary phases (CSPs) such as Chiralpak IA and Chiralpak IG. Supercritical fluid chromatography (SFC) was employed to carry out this study. Both immobilized CSPs such as Chiralpak IA and IG have sown remarkable selectivity for the reported drugs by using SFC. The values of retention factor (k) for ofloxacin enantiomers were 9.63 and 11.81, followed by 2.94 and 5.96 for cefotaxime enantiomers. The values of separation factor (α) for both the reported drugs were 1.22 and 2.03, respectively Similarly, the values of resolution factor (Rs) for both the enantio-selective drugs were 1.49 and 2.06, separately and respectively. The chiral recognition mechanism was developed and it was observed that the π-π interactions are playing a major role. The developed method is effective, reproducible, eco-friendly, and may be used to discriminate the enantiomers of the reported drugs in any sample.

Chiral separation of β-blockers is performed by utilizing the supercritical fluid chromatographic method. The chiral columns utilized were Chiralpak IG and Chiralpak IBN-5. The finest mobile phase was CO2 −0.2% TEA in methanol (60:40). The values atenolol enantiomers retention factors were 6.39 and 8.98. These values for propranolol enantiomers were 3.39 and 4.06. These values for betaxolol enantiomers were 4.08 and 4.68. The separation and resolution factor values for atenolol, propranolol, and betaxolol were 1.41 and 3.33, 1.19 and 2.23, and 1.15 and 1.87, separately and respectively. By comparison, it was observed that Chiralpak IG column is better than Chiralpak IBN-5 column. Supercritical fluid chromatography has been found as the best analytical technique due to its high speed, being eco-friendly, and being economic. The various most probable interactions responsible for the chiral resolution are hydrogen bonding, dipole–dipole interactions, steric effect, and π–π interactions. The reported methods are effective, efficient, and reproducible and may be used to separate and identify atenolol, propranolol, and betaxolol in any unknown samples.

Background: This work reports a green analytical method for the determination of organic environmental pollutants using nano-liquid chromatography with a self-made column for rapid, sensitive, inexpensive and efficient analysis of BTX pollutants in water. The applications of monolithic nanoscale columns for quantitative analysis of environmental real samples are very limited in the literature. Methods: A capillary column containing a composite of multi-walled carbon nanotubes incorporated into a lauryl methacrylate-co-ethylene dimethacrylate porous monolithic polymer was fabricated for the determination of BTX pollutants in real water samples. Results: Baseline separation was accomplished at 0.4 µL/min flow rate with UV-detection set at 208 nm. Under the optimum conditions, the calibration curves were validated over the range of 1.0-500 µg/L with R2 more than 0.9992. The detection limits of benzene, toluene, o-xylene and m/p-xylene were 0.25, 0.05, 0.075 and 0.05 µg/L, respectively. After a simple extraction process with a theoretical preconcentration factor equal to 200, the recovery values in Milli-Q, tap and sea water samples were found to be ranged from 84.85 to 97.84% with %RSD less than 7.5. Furthermore, we reported a comparison between our prepared composite column with a commercial C18 silica based column which is the most used in such analytical field. Each column demonstrated its advantages from different analytical aspects. Conclusion: The application of monolithic columns and nano-scale LC for routine analysis of environmental samples is very promising as the use of monolithic capillary columns offers several advantages over conventional scale particulate packed columns.

Additional file 1: Table S1. Multivariable log-binomial regression of the association between sexual behaviour and female circumcision among ever married women aged 15–49 years.

Additional file 2: Table S2. Multivariable log-binomial regression of the association between sexual behaviour and female circumcision among never married women aged 15–49 years.

Additional file 2. Distribution and Prevalence of at least 4 ANC visits by women empowerment components in Nigeria, Mali, Guinea and Zambia DHS 2018.

Additional file 1. Variables extracted for the composition of women empowerment Indicators.

Additional file 5. Unadjusted and Adjusted ordinal logistic regression of the association between background characteristics and early timing of ANC visits (≤ 3 months gestation) in Nigeria, Mali, Guinea and Zambia DHS 2018.

Additional file 4. Unadjusted and Adjusted ordinal logistic regression of the association between background characteristics and ≥ 4 ANC visits in Nigeria, Mali, Guinea and Zambia DHS 2018.

Additional file 3. Unadjusted and Adjusted ordinal logistic regression of the association between background characteristics and ≥ 8 ANC visits in Nigeria, Mali, Guinea and Zambia DHS 2018.

Analogous novel zwitterionic dimeric surfactants in the sequence of 2-dodecylphosphate,1-(N,N-dimethyl,N-dodecylammonium)ethane abbreviated as C12(-)–2–C12(+); 2-dodecylphosphate,1-(N,N-dimethyl,N-tetradecylammonium)ethane abbreviated as C12(-)–2–C14(+); and 2-dodecylphosphate,1-(N,N-dimethyl,N-hexadecylammonium)ethane abbreviated as C12(-)–2–C16(+); with phosphodiester anion and quaternary ammonium salt as hydrophilic and the methylene chains as hydrophobic groups, two methylene groups separate the two headgroups, were prepared, and the effect of aromatic hydrotropes aniline hydrochloride (AHC) and sodium salicylate (NaSal) on the mode of micellization at four unlike temperatures with a difference of 5 K in aqueous medium by the method of conductivity were studied. The decrease in cmc of zwitterionic surfactants with the addition/increase in bulk mole fraction of NaSal and AHC is almost linear. But anionic NaSal is more productive as compared to the cationic hydrotrope AHC in reducing the critical micelle concentration (cmc). Negative values of interaction parameter (βm) were found to decline with extension in one of the hydrophobic chain lengths keeping the other hydrophobic chain length identical. Symmetrical zwitterionic surfactants interact more strongly via headgroups and hydrocarbon tails with aromatic hydrotropes and decrease the cmc effectively by concealing of headgroups and hydrophobic forces operating mutually thus promotes micellar shape transition by alteration of micelle surface curvature. The enthalpy of micellization Δ mic H ° suggest an endothermic process and the negative value of free energy of micellization Δ mic G ° due to encouraging augmentation in entropy of micellization Δ mic S ° . The doping of surfactants with organic salts or hydrotropes amplifies the solubilizing power, viscosity and subdue the cmc value. Such systems promise to improve the performance used in separation methods, drug permeation, and delivery as these surfactants are less toxic and less sensitive to changes in pH and ionic strength.

In the present study, we have fabricate lithium magnesium borate glasses doped with different Cu2+ contents using the melt quench technique. The fabricated nanocomposites were characterized via FTIR, XRD, Raman and DRS analysis. The XRD pattern of all the nanocomposite definite the amorphous nature and the IR spectra revealed the presence of BO3 and BO4 units in the nanocomposites. The fabricated nanocomposites were used for solid state thermoluminescence dosimetry under the gamma radiation (cobalt, Co-60 source). The optimum annealing temperature was found to be 300 °C within 60 min. The results revealed that an enhancement in the TL intensity with the increment a certain amount of Cu2+ into the Lithium magnesium borate (LMB) samples. The fabricated nanocomposites show excellent TL intensity, reproducibility and a good linearity with linear regression coefficient of 0.9980 and 0.9949 with the dose range of 1–10 Gy and 10–100 Gy, respectively. These attractive outcomes exhibit that our fabricated nanocomposites can be used in personal, environmental and medical radiation therapy applications in future.

Sporopollenin microparticles have been prepared form Lycopodium clavatum spores, defatted and incorporated into a porous methacrylate polymer monolith to enhance liquid chromatographic performance of different sets of small neutral molecules. A stable suspension between sporopollenin microparticles and porogenic solvents composed of 1-propanol and 1,4-butandiol has proved before preparation, and seven compositions with increasing sporopollenin microparticles were prepared inside fused silica tubing. After optimizing of the preparation conditions, the structure of the stationary phase was characterized by scanning electron microscopy, surface area analysis, thermodynamic study, short- and long-term precision, and hydrodynamic properties including mechanical stability, porosity, and permeability. The columns were successfully applied to improve the separation efficiency of different mixtures using capillary liquid chromatography. Addition of very small amount of sporopollenin microparticles to the m...

Additional file 2. Determinant of fertility by regions based on the adjudged best model.

A monolithic capillary column containing a composite of metal–organic framework MIL-53(Al) incorporated into hexyl methacrylate-co-ethylene dimethacrylate was prepared to enhance the separation of mixtures of small aromatic compounds by using capillary liquid chromatography. The addition of 10 mg/mL MIL-53(Al) microparticles increased the micropore content in the monolithic matrix and increased the Brunauer–Emmett–Teller surface area from 26.92 to 85.12 m2/g. The presence of 1,4-benzenedicarboxylate moieties within the structure of MIL-53(Al) as an organic linker greatly influenced the separation of aromatic mixtures through π–π interactions. High-resolution separation was obtained for a series of alkylbenzenes (with resolution factors in the range 0.96–1.75) in less than 8 min, with 14 710 plates/m efficiency for propylbenzene, using a binary polar mobile phase of water/acetonitrile in isocratic mode. A reversed-phase separation mechanism was indicated by the increased retention factor and resolution as the water percentage in the mobile phase increased. A stability study on the composite column showed excellent mechanical stability under various conditions. The higher resolution and faster separation observed at increased temperature indicated an exothermic separation, whereas the negative values for the free energy change of transfer indicated a spontaneous process.