Psychometric properties of the Problematic Internet Use Questionnaire Short-Form (PIUQ-SF-6) in a nationally representative sample of adolescents

Despite the large number of measurement tools developed to assess problematic Internet use, numerous studies use measures with only modest investigation into their psychometric properties. The goal of the present study was to validate the short (6-item) version of the Problematic Internet Use Questionnaire (PIUQ) on a nationally representative adolescent sample (n = 5,005; mean age 16.4 years, SD = 0.87) and to determine a statistically established cut-off value. Data were collected within the framework of the European School Survey Project on Alcohol and Other Drugs project. Results showed an acceptable fit of the original three-factor structure to the data. In addition, a MIMIC model was carried out to justify the need for three distinct factors. The sample was divided into users at-risk of problematic Internet use and those with no-risk using a latent profile analysis. Two latent classes were obtained with 14.4% of adolescents belonging to the at-risk group. Concurrent and convergent validity were tested by comparing the two groups across a number of variables (i.e., time spent online, academic achievement, self-esteem, depressive symptoms, and preferred online activities). Using the at-risk latent profile analysis class as the gold standard, a cut-off value of 15 (out of 30) was suggested based on sensitivity and specificity analyses. In conclusion, the brief version of the (6-item) PIUQ also appears to be an appropriate measure to differentiate between Internet users at risk of developing problematic Internet use and those not at risk. Furthermore, due to its brevity, the shortened PIUQ is advantageous to utilize within large-scale surveys assessing many different behaviors and/or constructs by reducing the overall number of survey questions, and as a consequence, likely increasing completion rates

Use of eggshell membrane as an immobilization platform in microbial sensing

A new microbial biosensor was developed by immobilizing Pseudomonas fluorescens cells on eggshell membrane via physical adsorbtion. Bacteria-modified eggshell membrane was fixed tightly onto the surface of a carbon paste electrode (CPE) with a silicone rubber o-ring to construct a microbial biosensor. The measurements were based on the respiratory activity of the cells caused by oxygen consumption during bacterial metabolism. A mediated biosensor was also developed by ferrocene. As well as the response characteristics, stabilities and substrate specificities were investigated. Data were given as the comparison of mediated and unmediated systems. Copyright © Taylor & Francis Group, LLC

Immobilized Jerusalem artichoke (Helianthus tuberosus) tissue electrode for phenol detection

WOS: 000222338200010PubMed ID: 15274436A tissue based biosensor for the determination of phenol was developed by using Jerusalem artichoke (Helianthus tuberosus) in combination with a dissolved oxygen (DO) probe. The tissue electrode response depends linearly on phenol concentration between 0.002 and 0.010 muM in 10 min response time. Maximum electrode response was found in phosphate buffer at pH 8.0 and 35 degreesC. The reproducibility of the enzyme electrode was also tested by using standard phenol solutions (0.005 muM). The standard deviation (SD) and variation coefficient (cv) were calculated as +/-1.4 x 10(-4) muM and 3.1%, respectively

Bienzymatic fluorescence detection based on paraoxonase and laccase on anthracene-sequestered polyamic acid films: A novel approach for inhibition-based sensors

A fluorescence assay based on paraoxonase (PO) and laccase (Lac) immobilized on anthracene-sequestered polyamic acid films is now being reported for the first time for ciprofloxacin (CFx) detection. In enzymatic reaction, PO converts phenyl acetate (PA) to acetic acid and phenol. The formed phenol is further oxidized by laccase using oxygen as a co-substrate. For indirectly fluorescence measurements of PA hydrolysis, increased fluorescence intensity was measured after oxygen consumption by laccase. This is because oxygen is quencher of anthracene (Ant) incorporated in the sequestered poly(amic) acid (PAA) film. The detection mechanism was based on inhibition of PO activity by CFx. Using PAA provided the advantage of controlling the film thickness. Firstly, morphology of PAA-Ant polymeric film was characterized by scanning electron microcopy (SEM) and the success of PO-Lac immobilization on PAA-Ant was proven by SEM plus Energy-dispersive X-ray spectroscopy (SEM-EDX) and fluorescence measurements. Then Ant-PAA/PO/Lac is calibrated for PA and CFx without any interfering of some potential interferences. All results make it a promising tool for monitoring CFx at minute levels in samples. © 2020 Elsevier Ltd2017FEN012Authors thank to Ege University Research Foundation (Project no: 2017FEN012) for support