Poly(methyl methacrylate)/clay nanocomposites by photoinitiated free radical polymerization using intercalated monomer

A series of poly(methyl methacrylate)/montmorillonite (PMMA/MMT) nanocomposite were prepared by Successfully dispersing the inorganic nanolayers of MMT clay in an organic PMMA matrix via in situ photoinitiated free radical polymerization. Methyl methacrylate monomer was first intercalated into the interlayer regions of organophilic clay hosts by click chemistry followed by a typical photoinitiated free radical polymerization. The intercalated monomer was characterized by FT-IR spectroscopy, elemental analysis and thermogravimetric analysis methods. The intercalation ability of the modified monomer and exfoliated nanocomposite structure were confirmed by X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Thermal stability of PMMA/MMT nanocomposites was also studied by both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). (c) 2009 Elsevier Ltd. All rights reserved

Volume CXIV, Number 4, November 7, 1996

Objective: Turner syndrome (TS) is a chromosomal disorder caused by complete or partial X chromosome monosomy that manifests various clinical features depending on the karyotype and on the genetic background of affected girls. This study aimed to systematically investigate the key clinical features of TS in relationship to karyotype in a large pediatric Turkish patient population.Methods: Our retrospective study included 842 karyotype-proven TS patients aged 0-18 years who were evaluated in 35 different centers in Turkey in the years 2013-2014.Results: The most common karyotype was 45,X (50.7%), followed by 45,X/46,XX (10.8%), 46,X,i(Xq) (10.1%) and 45,X/46,X,i(Xq) (9.5%). Mean age at diagnosis was 10.2±4.4 years. The most common presenting complaints were short stature and delayed puberty. Among patients diagnosed before age one year, the ratio of karyotype 45,X was significantly higher than that of other karyotype groups. Cardiac defects (bicuspid aortic valve, coarctation of the aorta and aortic stenosis) were the most common congenital anomalies, occurring in 25% of the TS cases. This was followed by urinary system anomalies (horseshoe kidney, double collector duct system and renal rotation) detected in 16.3%. Hashimoto's thyroiditis was found in 11.1% of patients, gastrointestinal abnormalities in 8.9%, ear nose and throat problems in 22.6%, dermatologic problems in 21.8% and osteoporosis in 15.3%. Learning difficulties and/or psychosocial problems were encountered in 39.1%. Insulin resistance and impaired fasting glucose were detected in 3.4% and 2.2%, respectively. Dyslipidemia prevalence was 11.4%.Conclusion: This comprehensive study systematically evaluated the largest group of karyotype-proven TS girls to date. The karyotype distribution, congenital anomaly and comorbidity profile closely parallel that from other countries and support the need for close medical surveillance of these complex patients throughout their lifespa

The SIB Swiss Institute of Bioinformatics' resources: focus on curated databases

The SIB Swiss Institute of Bioinformatics (www.isb-sib.ch) provides world-class bioinformatics databases, software tools, services and training to the international life science community in academia and industry. These solutions allow life scientists to turn the exponentially growing amount of data into knowledge. Here, we provide an overview of SIB's resources and competence areas, with a strong focus on curated databases and SIB's most popular and widely used resources. In particular, SIB's Bioinformatics resource portal ExPASy features over 150 resources, including UniProtKB/Swiss-Prot, ENZYME, PROSITE, neXtProt, STRING, UniCarbKB, SugarBindDB, SwissRegulon, EPD, arrayMap, Bgee, SWISS-MODEL Repository, OMA, OrthoDB and other databases, which are briefly described in this article

Nanoparticle and gelation stabilized functional composites of an ionic salt in a hydrophobic polymer matrix

Polymer composites consisted of small hydrophilic pockets homogeneously dispersed in a hydrophobic polymer matrix are important in many applications where controlled release of the functional agent from the hydrophilic phase is needed. As an example, a release of biomolecules or drugs from therapeutic formulations or release of salt in anti-icing application can be mentioned. Here, we report a method for preparation of such a composite material consisted of small KCOOH salt pockets distributed in the styrene-butadiene-styrene (SBS) polymer matrix and demonstrate its effectiveness in anti-icing coatings. The mixtures of the aqueous KCOOH and SBS-cyclohexane solutions were firstly stabilized by adding silica nanoparticles to the emulsions and, even more, by gelation of the aqueous phase by agarose. The emulsions were observed in optical microscope to check its stability in time and characterized by rheological measurements. The dry composite materials were obtained via casting the emulsions onto the glass substrates and evaporations of the organic solvent. Composite polymer films were characterized by water contact angle (WCA) measurements. The release of KCOOH salt into water and the freezing delay experiments of water droplets on dry composite films demonstrated their anti-icing properties. It has been concluded that hydrophobic and thermoplastic SBS polymer allows incorporation of the hydrophilic pockets/phases through our technique that opens the possibility for controlled delivering of anti-icing agents from the composite

Relaxations in molecularly thin simple liquid films:linear viscoelasticity and non-linear response to shear

To understand the relaxations of molecules under confinement, the linear and nonlinear response of molecularly thin simple liquid films confined between two solid surfaces were studied. The method was to measure the resistance to applied oscillatory shear deformation as a function of frequency and amplitude of deformation, film thickness and normal pressure using the modified surface forces apparatus technique. The investigation of the frequency spectra of linear viscoelastic response as a function of the film thickness with octamethylcyclotetrasiloxane (OMCTS) films confined between mica surfaces showed more than two orders of magnitude increase in the relaxation times from 7 to 1 molecular layers. The frequency spectra taken at different film thicknesses were found to superpose onto a master curve when shifted horizontally and vertically. The successful superposition of the frequency spectra of both predominantly viscous and elastic response was concluded to show that a discontinuous phase transition was not involved in the transition to the confinement induced elastic state, also ruling out the possibility of a phase transition from linear to non-linear response. The transition from linear to non-linear response of elastic squalane films was associated with the yield of structure in the thin film. The transition as a function of applied force was reversible and repeatable, but with a significant hysteresis. Within the hysteresis loop, the time evolution of the viscoelastic parameters showed significant fluctuations in the form of triangular spikes on a constant baseline. The durations of the spikes were much larger than the oscillation period indicating a correlation of these changes over many periods. The dependence of the fluctuation amplitudes on the applied shear force was concluded to show the competition between the intermolecular forces and the externally applied shear.U of I OnlyThesi

TÜRKİYE’DE HANEHALKLARININ BALIK TÜKETİM HARCAMALARI: LOGIT VE MULTINOMIAL LOGIT YAKLAŞIMLARI

Çalışmada insan sağlığı üzerinde kanıtlanmış olumlu etkileri olan balık tüketiminin Türkiye hanehalkları için belirleyicileri analiz edilmiştir. Bu amaçla Türkiye İstatistik Kurumu'nun 2018 yılı Hanehalkı Bütçe Araştırması Mikro Veri Setinde yer alan 11.818 hanehalkına ait veriler Logit ve Multinomial Logit (MNL) modelleri ile tahminlenmiştir. Logit modeli ile hanehalklarının balık tüketip tüketmeme kararlarında etkili olan faktörler belirlenmiştir. Model tahmin sonuçlarına göre hanehalkı tipi, gelir düzeyi, hanehalkı büyüklüğü, hanehalkı ortalama yaşı, hanehalkı reisinin eğitim düzeyi ile medeni durum değişkenlerinin balık tüketme kararında etkili oldukları tespit edilmiştir. MNL modeli ile ise balık tüketen hanehalkları içinde balık tüketim harcamasını etkileyen faktörler analiz edilmiştir. Model tahmin sonuçlarına göre modele dahil edilen değişkenlerin tamamının, hanehalklarının balık harcamalarının 60 TL ve üzerinde olma olasılığını pozitif yönde etkilerken, 20 TL’nin altında olma ihtimalini de negatif etkilediği tespit edilmiştir

Determination of Some Physico-Mechanical Properties of Pellet Feed Used in Animal Nutrition

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