Stimuli-responsive Hydrogele und Poren-gefüllte Hydrogel Kompositmembranen

Classical bulk temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels were prepared via free radical polymerization in the presence of N,N’-methylenebisacrylamide (MBAAm) as a crosslinker. Two different initiation methods were studied: redox and photoinitiation. It was demonstrated that the desired final properties of resulting hydrogels, i.e., high monomer conversion and adjustable swelling were only achieved by selecting best suited initiation conditions. For redox polymerization, this was done by tuning the ratio of accelerator N,N,N',N'-tetramethylenediamine to initiator ammonium persulfate. The key parameters for achieving optimum photopolymerization conditions were photoinitiator concentration and UV irradiation time. With the help of in situ rheological measurements, optimum conditions could be further verified and quantified by monitoring the liquid-to-gel transition. Overall, photoinitiated crosslinking copolymerization was postulated to offer better options for in situ preparation of tailored functional hydrogels. Therefore the classical photopolymerized bulk PNIPAAm hydrogels were characterized in more details (swelling and mesh size, swelling recovery, volume expansion factor relative to synthesis state, morphology and partitioning of test solutes) as compared to redox hydrogels (swelling and mesh size). Rheology was also used to investigate the hydrogel after ex situ preparation, revealing “perfect” soft-rubbery behaviour. A good correlation between the mesh sizes determined from swelling and rheology was also found. Rheology has been found to be a powerful tool because it provides valuable data on polymerization and gelation kinetics as well as information about the hydrogels microstructure based on their viscoelastic character. The resulting optimum conditions from this part were utilized towards preparation and characterization of smart hydrogels that can respond to multiple stimuli and also functional pore-filling composite membranes. Temperature-responsive PNIPAAm hydrogels were imprinted with lysozyme via in situ photoinitiated crosslinking copolymerization. The three-dimensional network of the hydrogels was tailored by tuning the ionic content through methacrylic acid (MAA) as template-binding comonomer while keeping the ratio between crosslinker (MBAAm) and N-isopropylacrylamide (NIPAAm) fixed. The rheological data demonstrated that the onset of gelation was delayed with increasing MAA content. Moderate salt concentrations (0.3 M NaCl) were found to be suited for template removal without phase separation of the hydrogel. Swelling and protein (lysozyme and cytochrome C) binding were investigated for molecularly imprinted (MIP) and non-imprinted polymers (NIP) gels at temperatures below and above the lower critical solution temperature of PNIPAAm (32 °C). MIP gels showed a much higher affinity, selectivity and binding capacity for lysozyme compared to the NIP reference materials. Protein binding capacity was strongly reduced above 32 °C, to zero for NIP and to small values for imprinted gels. Most important, specific lysozyme binding to the MIP gels caused a large concentration dependent deswelling. This effect was much smaller for NIP gels, and the response could be modulated by the content of the comonomer methacrylic acid. It is envisioned that the alteration of swollen state of stimuli-responsive MIP hydrogels as functions of specific protein or temperature may govern the recognition-ability and binding-specificity towards establishment of novel biomimetic materials. A copolymer of PNIPAAm and 4-vinylbenzo-18-crown-6 (vCE) was synthesized via redox-initiation polymerization. The influence of vCE content on the copolymerization efficiency and also on the ion-recognition properties was investigated. The copolymerization was relatively efficient in a more loosely crosslinked network (rheology and Fourier transform infrared analyses). The swelling of PNIPAAm-co-vCE at 37 °C was higher in the presence of cations; i.e. Ba2+ > K+ than in pure water. The hydrogel copolymers were more sensitive at the higher ion concentration (0.02 M). The cation recognition and selectivity were further enhanced by the increase of vCE content in the hydrogel copolymers. Overall, this approach is interesting for the development of novel sensors or materials for controlled release applications. Hydrogel pore-filled composite membranes (HPFCM) based on polyethylene terephthalate (PET) track-etched membranes with pore diameters between 200 and 5000 nm and temperature-responsive PNIPAAm hydrogels were successfully prepared. A prefunctionalization of the pore walls by grafted linear PNIPAAm lead to stable anchoring of crosslinked PNIPAAm prepared in a subsequent step. Proper tuning of photopolymerization conditions resulted in desired microstructure of the hydrogels and thus tailored barrier properties of the composite membranes. The very interesting separation performance of HPFCM was due to diversification of the hydrogel network as function of its composition that caused adjustable sieving properties via synthesis conditions and also largely switchable barrier properties in response to the temperature. The interplay between the immobilized hydrogel and various pore sizes of the membrane support was also investigated. The base membrane provides mechanical support and confines the hydrogel within its pores, and it thus allows using the hydrogel mesh size for size-selective solute transport. Completely stable and selective HPFCM were only obtained with base pore sizes of about 2 µm or smaller. The size-selectivity (molecular weight cut-off) of the same HPFCM was higher under diffusive than under convective flow conditions; this is presumably mainly caused by elastic deformation of the hydrogel network. The cut-off from diffusion experiments was well correlated to mesh-size of the hydrogel determined from the Darcy model applied to permeability data obtained under convective flow conditions. Upon temperature increase beyond 32 °C, flux increased and rejection decreased very strongly; this remarkable change between macromolecule-size selective ultrafiltration and microfiltration/filtration behaviour was fully reversible. The smart performance of HPFCM could be interesting for the separation of multi-component mixtures or for controlled release due to the tunability of the sieving coefficient by changing the temperature

KOMUNIKASI PERSUASIF ERAT (ELDERLY RIGHT ADVOCACY TREATMENT) INDONESIA DALAM MEMBENTUK RASA KEPEDULIAN MASYARAKAT TERHADAP LANSIA DI KOTA YOGYAKARTA

Provinsi D.I Yogyakarta merupakan provinsi dengan angka lansia paling tinggi di Indonesia pada tahun 2022 menurut data dari Dukcapil D.I Yogyakarta. Tingginya angka lansia di Yogyakarta membuat munculnya banyak isu sosial terkait lansia. Untuk mengatasi isu sosial tersebut, muncul beberapa lembaga yang bergerak dalam mengatasi isu lansia, salah satunya ERAT Indonesia. Sebagai upaya mengatasi isu sosial tersebut, ERAT Indonesia menggunakan komunikasi persuasif untuk mencapai tujuannya. Komunikasi persuasif yang dilakukan ditujukan kepada anak muda yang turut mengikuti kegiatan-kegiatan lembaganya terkait lansia. Untuk mengetahui komunikasi persuasif yang dilakukan ERAT Indonesia serta bagaimana pandangan anak muda, digunakan teori Kemungkinan Elaborasi. Untuk mendapatkan data yang tepat, dilakukan wawancara dengan beberapa anggota ERAT Indonesia serta beberapa anak muda yang terlibat dalam kegiatan ERAT Indonesia. Penelitian ini juga diperkaya dengan hasil observasi pada media sosial dan dokumentasi milik ERAT Indonesia. Pada penelitian ini ditemukan bahwa pihak ERAT Indonesia melakukan riset sebelum memaparkan materi terkait lansia pada kegiatannya. ERAT Indonesia juga melakukan pendekatan non formal dengan anak muda untuk mengetahui pandangannya terhadap lansia. Komunikasi persuasif yang dilakukan ERAT Indonesia kepada anak muda juga dilakukan secara tersirat pada kegiatan pelatihan gratis yang diadakan oleh pihaknya serta memanfaatkan media sosialnya. Ditemukan hambatan komunikasi persuasif yang dilakukan, diantaranya kurangnya SDM milik ERAT Indonesia serta pandemi yang berlangsung

Insect succession and decomposition patterns of carcasses in Sarawak, Malaysian Borneo

Insect succession and decomposition process on three types of carcasses were conducted in peat swamp forest in Kota Samarahan, Sarawak, Malaysia, from August 2007 until January 2008. Nine fresh animal carcasses were used as carcass model in forensic entomological research. Three experiments were conducted and using three species of animals, namely plantain squirrels, Callosciurus notatus, chickens, Gallus gallus, and toads, Duttaphrynus melanostictus. The objectives of this study are to determine the decomposition stages and the insect succession with decomposition of different types of carcass in a peat swamp forest. Five decomposition stages were observed during this study which were fresh, bloated, active decay, advanced decay and dry remains stages. A total of 38 species of insects (seven Orders and 14 families) were collected from the nine carcasses. The common species that visit all three types of carcasses were Chrysomya megacephala and C. rufifacies (Calliphoridae). Ambient temperatures and relative humidity showed a reciprocal relationship in all the locations where the readings were recorded from the carcasses. These data may be used as a reference for further studies in ecology and forensic entomology in Malaysia

Comparative Prevalence of Ectoparasitic Fauna on Birds from Selected Mainland and Island of Sarawak

A survey of ectoparasitic fauna on birds was conducted in October 2017 until January 2018. The aims of this study were to investigate the ectoparasitic fauna on birds and to compare its prevalence in the selected mainland and island of Sarawak. A series of sampling by using mist-net has been done in Mount Sadong and Satang Besar Island with a total of 1440 hours of sampling effort for each locality. A total of 53 individuals of birds were captured and examined for its ectoparasites. Twenty-one species of ectoparasites were recorded comprising four species of lice and 17 species of mites. Four species of lice and 11 species of mites were detected in Mount Sadong while eight species of mites and no lice were detected in Satang Besar Island. The prevalence of ectoparasites infested on birds in Mount Sadong (33.33%) was higher than Satang Besar Island (17.39%). The p-value (p= 0.474) indicated there was no significant difference between the prevalence of ectoparasites from both localities. The result is important since ectoparasites infestation could affect the survival of birds and has the potential transmission of zoonotic disease

Impact of carboxylation and hydrolysis functionalisations on the anti-oil staining behaviour of textiles grafted with poly(N-isopropylacrylamide) hydrogel

Novel hydrogel-modified textiles have been prepared through photografting poly(N-isopropylacrylamide) (PNIPAAm) onto pristine and functionalised polyethylene terephthalate (PET) surfaces. In this work, two types of functionalisation, carboxylation (CPET) and hydrolysis (HPET), were performed to scrutinise the hydrogel grafting efficiency. Basic characterisation of the pristine, functionalised and grafted textiles was carried out via fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) analyses. Then, the functional characteristics of these samples were determined based on the oil staining performance. Functionalisation of the PET textiles via hydrolysis and carboxylation gives rise to different chemical reactivity and interactions on the PET surface. Impressively, the surface formed via hydrolysis functionalisation of PET was found to be more efficient compared to that formed via carboxylation, and the untreated one. The HPET surface was remarkably more hydrophilised and rougher than both the UPET and CPET surfaces. The accessibility of the -OH groups for hydrogen abstraction from HPET has a great impact on the hydrogel grafting onto the HPET surface. All the grafted textiles (PNIPAAm-g-UPET, PNIPAAm-g-CPET and PNIPAAm-g-HPET) demonstrated anti-oil staining behaviour at 27 °C. In particular, PNIPAAm-g-HPET textiles with a high degree of grafting (DG) exhibited the fastest rate for oil to de-stain from the surface. Moreover, the reversible transition of PNIPAAm hydrogels around the lower critical solution temperature (LCST) ~ 32 °C from hydrophilic to hydrophobic generates switchable surfaces of the textiles with regard to the oil wettability. Specifically, PNIPAAm-g-HPET textiles also displayed the highest degree of wettability switching as a result of having the highest DG. Taken together, the PNIPAAm hydrogels grafted onto PET textiles were significantly enhanced though hydrolysis functionalisation and possessed excellent switchable surfaces toward oil-staining, having great potential to be used for applications in oil and water separation as well as smart textiles

Collaborative Location-Based Mobile Game with Error Detection Algorithm

In the recent years, there has been an evolution in game input medium. From just using buttons, players can now interact with games through a wider spectrum of inputs which includes touch screen, camera, light sensor, accelerometer, compass and GPS. This is driven by the availability of these modules and sensors within mobile devices that are omnipresent nowadays. As a result, there has been a creative breakthrough on how games are played today where gaming experience can be made more intuitive and immersive. Localization is one of the input medium where the player’s physical location is used as part of the gameplay. This paper proposes an original gameplay schema that utilizes indoor mobile Wi-Fi localization technique as game input that does not require additional infrastructure. The game takes advantage of the weakness of Wi-Fi localization where environmental influence is significant and makes it part of the gameplay. A simple error detection algorithm is also introduced to maximize the game playability value by balancing game responsiveness and accuracy level

The Diversity, Distribution, and Habitat Preference of Rodents in Five Contrasting Habitats in the Tropical Rainforest of Malaysian Borneo

Rapid land-use changes may alter rodent assemblages in Malaysian Borneo. Understanding the diversity, distribution, and habitat preference of rodents from contrasting habitats may aid in pest control and conservation plan for rare species as well as species that important for conservation in Sarawak. In view of this, rodents were surveyed using cage and Sherman’s traps along several habitat gradients (primary forest, secondary forest, oil palm plantation, rural and urban areas) in Sarawak. This reveals that the highest species diversity was in the primary forest (H’=2.03) followed by the secondary forest (H’= 1.16), which decreased along the habitat gradient. Maxomys whiteheadi appeared as the indicator species in the primary forest (IndVal=0.894, p=0.033). Rattus tanezumi (n=155) appeared as the generalist followed by Sundamys muelleri (n=63) (PDI=0.61 and PDI=0.75, respectively). Meanwhile, three habitat specialists were detected (PDI=1.00), namely Leopoldamys sabanus, Maxomys surifer, and Niviventer rapit in the primary forest. Habitat preference analysis shows that most forest species were avoiding disturbed habitats and few species were recorded in disturbed habitats. This survey may provide information to aid various stakeholders in understanding rodent ecology for conservation purposes and pest control mitigation plans in Sarawak

Lignin-coated polystyrene/trichloromethylsilane absorbent for oil spill cleanup

The study was conducted to determine the effectiveness of lignin-polystyrene/ trichloromethylsilane (TL-PS) absorbent in removing oil spillage from wastewater. Lignin powder obtained from the delignification of oil palm empty fruit bunch (OPEFB) was coated with PS emulsion (PSE) at various concentrations (2, 4, 6, & 8 mL) in order to bind the powder into an aggregated form. Later, L-PS was exposed to trichloromethylsilane (TCMS) via chemical vapour deposition method (CVD) at fixed 7.5 min exposure time to form TL-PS absorbent. The wettability of TL-PS was determined by conducting water contact angle (WCA) measurement and oil sorption capacity. It was found that TL-PS4 sample (immersed in 8 mL PSE) had the highest WCA value (134.10°) and oil sorption capacity (52%) in comparison with L-PS4 (immersed in 8 mL PSE without TCMS) with WCA value of 99.10° and oil sorption capacity of 40%. Meanwhile, the disappearance of hydroxyl group (OH) at peak 3429 cm-1 and appearance of siloxane bonds (R-Si-O) at peak in range of 1000 - 1100 cm-1 and 3.9 - 4.0 ppm had confirmed the substitution occurred between these groups, as shown by the spectra obtained from attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and nuclear magnetic resonance (NMR). Thermal stability of TL-PS4 (onset degradation temperature at 252 °C) was higher when compared with lignin (onset degradation temperature at 40 °C), as showed by the thermogravimetric analysis (TGA). Meanwhile, the surface of absorbent had change from smooth (L-PS4) to rough (TL-PS4) corresponding to the deposition of silane particles onto the surface of L-PS after the exposure with TCMS, as shown by the scanning electron microscopy (SEM). The results suggested that TL-PS has a promising potential to be used as an absorbent for oil spill cleanup