Search

To improve the salt tolerance/sensitivity of cellulose nanofibrils (CNFs), zwitterionic cellulose nanofibrils (ZCNFs) were prepared from softwood bleached kraft pulp fibers via a sequential process of anionic modification with 2,2,6,6-tetramethylepiperidin-1-oxyl (TEMPO)-mediated oxidation, cationic modification with (2,3-epoxypropyl) trimethylammonium chloride (EPTMAC), and high-pressure homogenization. To produce ZCNFs with different contents of cation group, EPTMAC loadings of 0.15 to 1.15 g/g fiber were explored during cationization. The obtained ZCNFs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectra (XPS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and rheological measurements. The salt tolerance of the ZCNFs was investigated by adding mixed salts into the ZCNF dispersions. The results demonstrated that the ZCNFs with both anionic and cationic charges were produced. Compared with the TEMPO-mediated oxidized cellulose nanofibrils (TOCNFs), the ZCNFs exhibited an excellent "salt-thickening" behavior under the studied salt concentrations (2-24% w/w). Moreover, increasing the content of the cation group increased the salt tolerance/sensitivity of ZCNFs. This work demonstrated that introducing cationic charges to the anionic charged TOCNFs imparts the produced ZCNFs with excellent salt sensitivity and tolerance, which could expand the application of nanocellulose in oil recovery or wastewater treatment.

The 2017 ACC/AHA blood pressure (BP) guidelines generated controversies due to the new proposed BP cut-off values defining hypertension. We aimed to assess aortic stiffness of subjects who are reclassified as stage 1 hypertensive according to the new guidelines and compare them with the subjects of "elevated BP" category. Background: The 2017 ACC/AHA blood pressure (BP) guidelines generated controversies due to the new proposed BP cut-off values defining hypertension. We aimed to assess aortic stiffness of subjects who are reclassified as stage 1 hypertensive according to the new guidelines and compare them with the subjects of "elevated BP" category. Patients and methods. Data from the "Corinthia" study, an observational, cross-sectional survey of 2,043 participants were analyzed. Subjects were classified into 4 groups: group A: systolic pressure (SBP) 120-129 and diastolic pressure (DBP) < 80 mmHg, group B: SBP 130-139 or DBP 80-89 mmHg, group B1: SBP 130-139 and DBP < 80 mmHg and group B2: SBP 130-139 and DBP 80-89 mmHg. Aortic stiffness was assessed by carotid-to-femoral pulse wave velocity (PWV). A value of PWV > 10m/s was consider indicative of asymptomatic organ damage while values of PWV exceeded the 90 % percentile for each age group were consider as abnormal. Results: Groups B, B1 and B2 have significantly increased PWV compared to group A, independently from age and other risk factors (PWV: 9.2 ± 2.8 vs 9.4 ± 2.7 vs 8.6 ± 2.5 vs 8.1 ± 2.3 m/s, p < 0.01, respectively). The prevalence of PWV > 10 m/s and abnormal PWV values in group A was significantly lower than the corresponding prevalence in randomly selected, age-matched subjects from group B (13.5 % vs 24.4 %, p = 0.027 and 5.6 % vs 14.2 %, p = 0.022, respectively). Conclusions: The reclassified subjects as stage 1 hypertensive by the new guidelines have a significantly increased aortic stiffness and greater prevalence in asymptomatic aortic damage compared to subjects with elevated BP. This finding may indirectly explain the increased cardiovascular risk of this group.