The synthesis of an amended membrane coated with graphene oxide and dopamine and guanidyl-based modifier and its antifouling properties

The membrane fouling issue has aroused great concern. To improve their antifouling properties, surface grafting with oxidative deposition were employed to amend a polyvinylidene fluoride (PVDF) membrane. The modifiers were amino-modified graphene oxide (AMGO), dopamine (DPA) and 1,3-diaminoguanidine hydrochloride (DAGH). To take bovine serum albumin (BSA, 1 g/l) as an example of organic materials, BSA interception rate and pure water flux recovery rate increased to 93.65% and 66.74%, respectively, while the corresponding values for the original membrane were much lower (72.82% and 31.72%). The optimum synthesis conditions were found to be 1.5 mg/ml of DPA, 1 wt% of DAGH, 2 mg/ml of AMGO, 4 h of DPA oxidation deposition time and 1 h of AMGO grafting time. Many functional groups like C = N, -NH₂, C = O and -OH improved the membrane surface hydrophilicity leading to a higher resistance to organic pollution. Dopamine and guanidyl facilitated the antimicrobial performance of the modified membrane, whose antimicrobial rate was up to 96%, while the raw membrane had no antimicrobial activity. The amended membrane possessed 40% higher mechanical strength than the initial one. It could withstand a high pumping suction force. The noteworthy property was that the irreversible fouling rate decreased by 55%. Therefore, the amended membrane could restore its flux much more easily.

Impact of social media usage on daytime sleepiness: A study in a sample of tertiary students in Singapore

Objective

Many tertiary students access social networking sites on a daily basis. With the increased usage of smartphones, accessing social networking sites while commuting, in schools, waiting for friends, television commercial breaks has become prevalent among tertiary students. What started as a lifestyle choice has now become a daily necessity. Such behavior among tertiary students raises an important question for educators: how does social media usage affect tertiary students’ sleep patterns and daytime sleepiness, their attention difficulties, especially in school? Thus, the aim of this study was to examine the relationships between tertiary students' self-reports of social media usage and daytime sleepiness.

Design

The design was a cross-sectional, quantitative research study.

Methods

We used a survey that contained questions concerning demographic data, daytime sleepiness, total sleep time and social media usage and a version of the Cleveland Adolescent Sleepiness Questionnaire, modified for use in tertiary students, were used for data collection (n = 969).

Results

The most preferred tool for accessing social networking sites was smartphones and WhatsApp was the most accessed site. Results indicated that nocturnal technology use has a weak, negative impact on tertiary students’ quantity of sleep that may lead to daytime sleepiness. Local Singapore students spent significantly more time on social networking sites at night compared to foreign students. As a result, local students experienced more daytime sleepiness compared to foreign students.

Conclusions

Prolonged social media usage, especially in bed, has a negative impact on tertiary students’ daytime sleepiness. Since the technology is such an integral part of most tertiary students’ lives, it is important to understand the impact it has on their sleep and daytime sleepiness.