Synthesis and structural characterization of block and random low molecular weight copolymers composed of L-lactic acid and isosorbide succinate moieties

Isosorbide succinate moieties were incorporated into poly(L-lactide) (PLLA) backbone in order to obtain a new class of biodegradable polymer with enhanced properties. This paper describes the synthesis and characterization of four types of low molecular weight copolymers. Copolymer I was obtained from monomer mixtures of L-lactide, isosorbide, and succinic anhydride; II from oligo(L-lactide) (PLLA), isosorbide, and succinic anhydride; III from oligo(isosorbide succinate) (PIS) and L-lactide; and IV from transesterification reactions between PLLA and PIS. MALDI-TOFMS and 13C-NMR analyses gave evidence that co-oligomerization was successfully attained in all cases. The data suggested that the product I is a random co-oligomer and the products II-IV are block co-oligomers.Resíduos de succinato de isosorbídeo foram incorporados na cadeia principal de poli(L-lactídeo) (PLLA) visando a obtenção de uma nova classe de polímeros biodegradáveis com propriedades melhoradas. Este artigo descreve a síntese e caracterização de quatro tipos de copolímeros de baixa massa molar. O copolímero I foi obtido da mistura dos monômeros L-lactídeo, isosorbídeo e anidrido succínico; II do oligo(L-lactídeo) (PLLA), isosorbídeo e anidrido succínico; III do oligo(succinato de isosorbídeo) (PIS) e L-lactídeo; e IV de reações de transesterificação entre PLLA e PIS. Análises de MALDI-TOFMS e 13C-NMR apresentaram evidências de que cooligomerização foi alcançada em todos os casos. Os dados sugerem que o produto I é um cooligômero aleatório e que os produtos II-IV são cooligômeros em bloco.CNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)FAPES

The Earthlike Shoreline Morphology of Titan's Ontario Lacus

Ontario Lacus' shoreline features include Earth-like rivers, deltas and flooded topography. Ontario is a dynamic lake, similar in many ways to terrestrial lakes, with active shoreline processes

Pontine tegmental cap dysplasia: developmental and cognitive outcome in three adolescent patients

Pontine Tegmental Cap Dysplasia (PTCD) is a recently described, rare disorder characterized by a peculiar cerebellar and brainstem malformation. Nineteen patients have been reported to date, of which only one in the adolescent age, and data on the clinical, cognitive and behavioural outcome of this syndrome are scarce

Local scale seismic landslide susceptibility assessment based on historic earthquake records combined with accelerometer monitoring and ambient noise data

Uncertainty in the quantification of earthquake loading poses one of the major difficulties in local scale seismic landslide susceptibility assessments. This problem can be exacerbated for slope settings that are likely to produce considerable amplifications of seismic shaking. We address this issue by examining the case of a historic landslide triggered by the 1627 Apulian (southern Italy) earthquake (epicentral intensity X on the MCS scale) in the peri-urban area of Caramanico (central Italy), distant ~120 km from the epicenter. The failure caused a large downslope displacement and destroyed several buildings. The slope seismic response is assessed using data from long-term accelerometer monitoring of the hillslope and from recent ambient noise measurements. This provided evidence of significant directional amplifications, e.g., by a factor of approximately 4 and 20, respectively in terms of peak horizontal acceleration and Arias Intensity during the 2009 Mw 6.3 L’Aquila earthquake that occurred 60 km NW of Caramanico. Then taking into account the site amplification, permanent displacements are calculated by applying a rigorous Newmark approach. This study shows that historical information on landslides triggered at apparently anomalously large distances from an earthquake epicentre can help to identify hillslopes influenced by site effects and that reconnaissancetype measurements of ambient noise can be useful to reveal directional amplifications. The importance of accurate assessments of other relevant input parameters (e.g., material properties, slip surface geometries, groundwater conditions) used in seismic slope modeling is also recognized

Sol LeWitt, Wall Drawing 445; Wall Drawing 494. Intervista ad Andrea Marescalchi

Andrea Marescalchi è stato un artista che ha collaborato a lungo con Sol Lewitt: ha partecipato alla realizzazione di molti dei suoi Wall drawings e messo a punto, insieme agli altri assistenti, le tecniche e le procedure di esecuzione pittorica, codificate in maniera specifica a seconda dei materiali scelti e degli effetti desiderati da Lewitt stesso. L'intervista è stata un'occasione preziosa per raccogliere i dettagli tecnici dei procedimenti e dei prodotti relativi alle opere murali realizzate con inchiostri, oltre che per approfondire il rapporto fra Sol Lewitt ed i suoi assistenti

Block Copolymers Containing (R)-3-Hydroxybutyrate and Isosorbide Succinate or (S)-Lactic Acid Mers

A new aliphatic block copolyester was synthesized in bulk from transesterification techniques between poly((R)-3-hydroxybutyrate) (PHB) and poly(isosorbide succinate) (PIS). Additionally, other two block copolyesters were synthesized in bulk either from transesterification reactions involving PHB and poly(l-lactide) (PLLA) or from ring-opening copolymerization of l-lactide and hydroxyl-terminated PHB, as result of a previous transesterification reactions with isosorbide. Two-component blends of PHB and PIS or PLLA were also prepared as comparative systems. SEC, MALDI-TOF mass spectrometry (MALDI-TOFMS), (1)H and (13)C NMR spectroscopy, WAXD, solubility tests, and TG thermal analysis were used for characterization. The block copolymer structures of the products were evidenced by MALDI-TOFMS, (13)C NMR, and WAXD data. The block copolymers and the corresponding binary blends presented different solubility properties, as revealed by solubility tests. Although the incorporation of PIS sequences into PHB main backbone did not enhance the thermal stability of the product, it reduced its crystallinity, which could be advantageous for faster biodegradation rate. These products, composed of PHB and PIS or PLLA sequences, are an interesting alternative in biomedical applications.CapesCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CNPqConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fapes

Photocatalytic TiO 2 coatings on limestone

The application of photocatalytic coatings on stone has been investigated for providing surface protection and self-cleaning properties. Sol-Gel and hydrothermal processes were used to synthesise TiO 2 colloidal suspensions and coatings with enhanced photocatalytic activity without any thermal curing of the coated stone. The stone was a porous limestone (apulian sedimentary carbonatic, calcite stone). Films and powders prepared from TiO 2 sols were studied using X-ray diffraction to evaluate the microstructure and identify rutile and anatase phases. A morphological and physical characterisation was carried out on coated and uncoated stone to establish the changes of appearance, colour, water absorption by capillarity and water vapour permeability. The photocatalytic activity of the coated surface was evaluated under UV irradiation through NO x and organics degradation tests. The performances of the synthesised TiO 2 sols were compared with commercial TiO 2 suspension. Since the coating doesn't need temperature treatments for activating the photocatalytic properties, the nano-crystalline hydrothermal TiO 2 sols seem good candidate for coating applications on stone that cannot be annealed after the coating application. © 2011 Springer Science+Business Media, LLC

Crystalline particles from self-assembled divinyl oligomers

Ethylene glycol dimethacrylate (EGDMA) and/or triethylene glycol dimethacrylate (TEGDMA) oligomers formation was catalyzed in aqueous medium by horseradish peroxidase (HRP) in the presence of H(2)O(2) at room temperature. EGDMA and/or TEGDMA oligomers were characterized by means of gel permeation chromatography, infrared vibrational spectroscopy and (1)H NMR spectroscopy. Self-assembling of oligomers led to right-angled crystalline particles, as evidenced by scanning electron microscopy and differential scanning calorimetry. EGDMA, TEGDMA and EGDMA-co-TEGDMA oligomers synthesized in the presence of HRP-H(2)O(2) system presented pendant vinyl groups along the chains. good solubility in chloroform, and well-defined melting point. These features evidenced few cross-linking or cyclization and revealed that the catalytic properties of HRP led to oligomeric materials with new characteristics. (C) 2008 Elsevier B.V. All rights reserved.FAPESPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNP

Efficacy of vigabatrin intervention in a mild phenotypic expression of succinic semialdehyde dehydrogenase deficiency

We report a patient with succinic semialdehyde dehydrogenase deficiency who presented a mild phenotype including developmental language delay, in association with the typical elevations of 4-hydroxybutyric acid (GHB) in biological fluids and MRI alterations. Two pathogenic mutations were identified one transversion (c.278 G\u3e T) in exon 1 and another (c.1557 T\u3e G) in exon 10. Both parents are carriers of one of the mutations, confirming compound-heterozygosity in their affected child. To reduce the GHB levels in body fluids, a treatment with vigabatrin at low dose (25 mg/kg per day) was started, monitoring its efficacy by clinical and neurochemical follow-up. After 9 months of therapy with vigabatrin, a significant reduction of GHB concentrations in urine and CSF was observed; after 36 months, a significant improvement of communicative skills, not previously reported, was referred. These results support the hypothesis that the clinical improvement is correlated to the reduction in the GHB levels and the importance of considering the SSADH deficiency in the differential diagnosis of patients with mental retardation and language delay