Aim of this study was to produce hydrophilic breathable polyurethane membranes providing antibacterial property permanently by incorporation of a quaternary ammonium salt diol (QAS). The study was carried out by synthesis of nine different polyurethanes by solution polymerization through variations of their QAS and isocyanate contents. Fully amorphous membranes at a thickness of~30 μm were produced from the synthesized polymers and their thermal and morphological characteristics were determined. The effect of morphological structures on the membrane water vapor transmission rates (WVTR) and antibacterial properties were correlated. The WVTR increased with the increased temperature in all membranes over 10-40 C, all produced membranes showed water resistance up to a pressure of 2100 cmH2O and WVTR values above 60 g/m 2 h at 30 C. The WVTR increased by increasing amount of QAS including cationic groups and decreased by increasing isocyanate amount reducing the molecular chain flexibility. In addition, while the unmodified membranes did not show any antibacterial activity, the QAS-added membranes provided significant inactivation against Staphylococcus aureus and Escherichia coli of about 104 CFU within 5 h of contact time.
Antibacterial PVDF flat sheet membranes are produced with the directly incorporation of novel synthesized N-halamine copolymers having high chlorine loading capacity and compatible with the base polymer. FTIR and 1 H NMR analysis are applied to the synthesized polymers and the presence of the polymers in the produce membrane structures are determined with FTIR and XPS analysis. To get information about phase separation behavior of the membrane solutions, ternary phase diagrams of the synthesized copolymers, PVDF, and their mixed solutions are prepared. The effect of synthesized polymers on membrane pore formation is revealed with ternary phase diagrams, water flux performance, BSA rejection performance, and SEM images of the produced membranes. Two different biocidal tests are applied to the membranes to determine the effectiveness of the membrane surfaces against biofilm formation, the speed of antibacterial efficiency and the duration of the biocidal activity of the membranes. The tests results show that only a small amount of copolymer incorporation into PVDF membranes solutions enables to production of antibacterial membranes with a long-term and rapid efficacy against S. aureus and E. coli bacteria.
Dijitalleşmenin gittikçe yaygınlaştığı günümüzde, bireylerin gelişiminde ve üretkenliğinde ihtiyaç duydukları becerilerin arasında dijital okuryazarlık önemli bir yer tutmaya başlamıştır. Bu beceriler, okul öncesi öğretmenlerin de sahip olması gereken beceriler arasındadır. Bu araştırma, okul öncesi öğretmenlerinin dijital okuryazarlık düzeylerinin çeşitli değişkenler doğrultusunda incelenmesi amacı ile gerçekleştirilmiştir. İlişkisel tarama yönteminin kullanıldığı araştırmanın çalışma grubunu 114 okul öncesi öğretmeni oluşturmaktadır. Araştırmada katılımcıların demografik bilgilerini (yaş, kıdem yılı, çalışılan okul türü) belirlemek için Kişisel Bilgi Formu, dijital okur yazarlık düzeylerini belirlemek için ise Öğretim Teknolojileri, Bilgi ve İletişim ile Teknik olmak üzere üç alt boyuttan oluşan Dijital Okuryazarlık Ölçeği kullanılmıştır. Araştırmanın sonuçlarına göre öğretmenlerin dijital okuryazarlık düzeyleri tüm alt boyutlar için ortalamanın üstünde olarak belirlenmiştir. Araştırma sonuçlarında, öğretmenlerin yaşlarına göre dijital okuryazarlık düzeylerinin üç alt boyutta da farklılaştığı; kıdem yıllarına göre ise bilgi ve iletişim ile teknik alt boyutlarında dijital okur-yazarlık düzeylerinde farklılaşma görülmektedir.
In this study, polyvinylidene fluoride (PVDF) polymeric membranes with addition of functionalized carbon-based material (CBM) were fabricated by using electrospinning technique for the removal of cationic dyes from wastewater. CBM was prepared through a two-step carbonization process from cotton linter as an agricultural waste biomass. The characterization of CBM was performed by using Brunauer–Emmett–Teller (BET) surface analysis, fourier transform infrared spectrometry (FTIR) and elemental analysis. The morphologies of electrospun membranes were observed by scanning electron microscope (SEM) which clearly revealed that nanofibers with a smooth surface were produced by incorporation of CBM. According to the results obtained from FTIR and differential scanning calorimetry (DSC), crystallization behavior of PVDF membranes was promoted by increasing the percentage of CBM in the membrane. PVDF membrane prepared with the addition of 3 wt % CBM exhibited the highest water flux performance with a dye rejection of 74.6 % in comparison with the pure PVDF one.
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