Photoferroelectric oxides

Giant photovoltaic effect due to bulk photovoltaic effect observed in multiferroic BiFeO3 thin films has triggered a renewed interest on photoferroelectric materials for photovoltaic applications. Tremendous advance has been done to improve power conversion efficiency (up to up to 8.1%) in photoferroelectrics via absorption increase using narrow bandgap ferroelectrics. Other strategies, as it is the more efficient use of ferroelectric internal electric field, are ongoing. Moreover, as a by-product, several progress have been also achieved on photostriction that is the photo-induced deformation phenomenon. Here, we review ongoing and promising routes to improve ferroelectrics photoresponse

Effect of morphology and defectiveness of graphene-related materials on the electrical and thermal conductivity of their polymer nanocomposites

In this work, electrically and thermally conductive poly (butylene terephthalate) nanocomposites were prepared by in-situ ring-opening polymerization of cyclic butylene terephthalate (CBT) in presence of a tin-based catalyst. One type of graphite nanoplatelets (GNP) and two different grades of reduced graphene oxide (rGO) were used. Furthermore, high temperature annealing treatment under vacuum at 1700{\deg}C was carried out on both RGO to reduce their defectiveness and study the correlation between the electrical/thermal properties of the nanocomposites and the nanoflakes structure/defectiveness. The morphology and quality of the nanomaterials were investigated by means of electron microscopy, x-ray photoelectron spectroscopy, thermogravimetry and Raman spectroscopy. Thermal, mechanical and electrical properties of the nanocomposites were investigated by means of rheology, dynamic mechanical thermal analysis, volumetric resistivity and thermal conductivity measurements. Physical properties of nanocomposites were correlated with the structure and defectiveness of nanoflakes, evidencing a strong dependence of properties on nanoflakes structure and defectiveness. In particular, a significant enhancement of both thermal and electrical conductivities was demonstrated upon the reduction of nanoflakes defectiveness

Effect of processing conditions on the thermal and electrical conductivity of poly (butylene terephthalate) nanocomposites prepared via ring-opening polymerization

Successful preparation of polymer nanocomposites, exploiting graphene-related materials, via melt mixing technology requires precise design, optimization and control of processing. In the present work, the effect of different processing parameters during the preparation of poly (butylene terephthalate) nanocomposites, through ring-opening polymerization of cyclic butylene terephthalate in presence of graphite nanoplatelets (GNP), was thoroughly addressed. Processing temperature (240{\deg}C or 260{\deg}C), extrusion time (5 or 10 minutes) and shear rate (50 or 100 rpm) were varied by means of a full factorial design of experiment approach, leading to the preparation of polybutylene terephthalate/GNP nanocomposite in 8 different processing conditions. Morphology and quality of GNP were investigated by means of electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry and Raman spectroscopy. Molecular weight of the polymer matrix in nanocomposites and nanoflake dispersion were experimentally determined as a function of the different processing conditions. The effect of transformation parameters on electrical and thermal properties was studied by means of electrical and thermal conductivity measurement. Heat and charge transport performance evidenced a clear correlation with the dispersion and fragmentation of the GNP nanoflakes; in particular, gentle processing conditions (low shear rate, short mixing time) turned out to be the most favourable condition to obtain high conductivity values

Penerapan Algoritma K-Means Clustering untuk Pengelompokkan Penyebaran Diare di Kabupaten Langkat

Diare merupakan penyakit yang bertanggung jawab untuk sekitar seperempat dari 130.000 kematian tahunan diantara anak Balita, terutama pada musim pancaroba seperti yang terjadi dihampir seluruh kawasan Indonesia tidak terlebih di kabupaten langkat Sumatera Utara. Untuk melihat kawasan penyebarannya perlu dibuat sebuah pengelompokan kawasan penyebaran diare, agar diperoleh daerah penyebaran diare dan pusat penyebarannya. Algoritma K-Means Clustering merupakan salah satu algoritma yang mengelompokkan data yang sama pada kelompok tertentu dan data yang berbeda pada kelompok yang lain. Hasil dari pengelompokkan daerah penyebaran diperoleh Kecamatan Batang Serangan, Brandan Barat dan Permata Jaya sebagai pusat penyebaran diare pada Cluster pertama dan Kecamatan Hinai dan Sei Bingai menjadi pusat cluster kedua

Durable graphite oxide nanocoating for high performing flame retarded foams

Recent developments in the design of water-based coatings encompassing platelet-like nanoparticles have clearly demonstrated the flame retardant potential of this approach for open cell flexible foams. However, the relatively high number of deposition steps required and the limited reports on the durability of the deposited coatings to multiple compression cycles currently represent the main constraints to this approach. This paper addresses these limitations by exploiting a few steps deposition procedure to produce coatings with durable flame retardant properties. Graphite oxide, sodium alginate and sodium hexametaphosphate were combined in a continuous protective coating that extends to the complex three-dimensional structure of the foam. The flame retardant properties of the coatings were evaluated before and after 1000 compression cycles. Even after such multiple deformations, the coated foams showed no melt dripping and self-extinguishment during flammability tests, as well as a highly reduced heat release rates (-70%) and total smoke release (-70%) during cone calorimetry tests. Furthermore, the ability to withstand the penetration of an impinging flame focused on one side of the coated foam for more than 5 min was also maintained. These results clearly demonstrate the durability of the coated foams, opening to real life application fields such as transports seats where high levels of flame retardancy must be maintained for long time under frequent mechanical stress

Kelimpahan Dan Kekayaan Artropoda Predator Pada Tanaman Padi Yang Diaplikasi Bioinsektisida Bacillus Thuringiensis

Abundance and species richness of the predatory arthropods on paddy treated with Bacillus thuringiensis bioinsecticide. Application of bioinsecticide from bacterial entomopathogen has not been reported yet that can decrease abundance and species richness of predatory arthropods, such as spiders and predatory insects. This research was aimed to analyze the abundance and species richness of predatory arthropods paddy fields applied by B. thuringiensis bioinsecticide on paddy in fresh swamp area. Areas observed were 2 ha paddy field's at Situ Bagendit variety. Predatory arthropods inhabiting canopy were sampled using sweep but soil dwelling arthropods were trapped using pitfall traps. The result showed that abundance of spiders inhabiting canopy decreased significantly after B. thuringiensis bioinsecticide application on paddy compared to control without bioinsecticide but the abundance of predatory insects were not significantly affected by the bioinsecticide. Application of the bioinsecticide did not significantly affect the abundance and species richness of soil dwelling predatory arthropods, such as spiders and predatory insects

Internal Genital Organ-preserving Radical Cystectomy: a Case Report

Adenocarcinoma of the bladder is usually managed by radical cystectomy. However, recent literature shows that internal genital organ-preserving radical cystectomy is feasible in selected cases in order to get a better impact on patient's psychology, sexuality and potential fertility. Here, we report a 32-year-old woman with adenocarcinoma of the bladder who was managed with internal genital organ-preserving radical cystectomy. The patient was never had any child and the radiologic examination (MRI) showed no involvement of internal genitalia organ. This procedure aims to maintain fertility potential of the patient. Intraoperatively, no adhesion was found between the tumor and internal genitalia organ. The internal genitalia organ was successfully preserved during the radical cystectomy