Search results for "Polyvinyl"
showing 10 items of 126 documents
Synergetic effect of gold in Au/Pd catalysts during hydrodesulfurization reactions of model compounds
2003
Abstract The simultaneous formation of colloidal dispersions of Pd and Au metal particles protected by the organic polymer polyvinylpyrrolidone (PVP) in reducing alcohol solution was used for the synthesis of new silica-supported monometallic and bimetallic Au x Pd y catalysts with different x / y ratios. The samples, with a 2 wt% total metal loading, after air calcinations at 673 K to remove the PVP, were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and FTIR spectra of chemisorbed CO. Formation of alloyed Au x Pd y particles of different metal composition with consequent modification of their electronic and geometric properties was ascertained. The catalytic activi…
Study and optimization of freeze-drying cycles of a model probiotic strain
2018
This work is based on the experimental study of the freeze-drying process to understand the impact of numerous factors on the survival rates of a model probiotic strain of Lactobacillus casei type. With the aim to find out if cell density in the matrix and survival rates are linked, we have studied the location of the cells after freeze drying inside a porous matrix composed of a lactose basis with a polymer, the polyvinylpyrrolidone (PVP) in various amounts. The best survival rate were obtained at slow freezing rate for a formulation containing 5% (m/V) of lactose and 5% (m/V) of PVP. Keywords: Freeze-Drying; Freezing; Probiotics; L. Casei ATCC 393
Structural Organization of Poly(vinyl alcohol) Hydrogels Obtained by Freezing and Thawing Techniques: A SANS Study
2005
The structural organization of matter in poly(vinyl alcohol) (PVA) hydrogels obtained by repeatedly freezing and thawing dilute solutions of PVA in D2O is investigated by use of small-angle neutron scattering measurements (SANS). This study is the first systematic and quantitative investigation in the medium range of length scales on PVA hydrogels obtained by freezing and thawing techniques. The studied gels have a complex hierarchical structure, extending over a wide range of length scales. The structural organization on the micron length scale originates from the presence of two separated phases constituted by polymer-rich and polymer-poor regions. The network structure may be interpreted…
Luminescent YPO4:Eu@PVA dispersions for anti-counterfeiting ink applications
2023
A method was developed to obtain YPO4:Eu dispersions of PVA as a luminescent inks. YPO4:Eu nanoparticles were prepared by precipitation followed by hydrothermal treatment. The dispersion preparation included systematic studies to prepare a stable colloidal system and to investigate the role of parameters affecting its stability and UV-excited YPO4:Eu emission intensity. The effect of PVA concentration was studied in detail for two different PVAs to determine the optimal parameters for its use as ink with specific luminescent properties. The type of interactions responsible for the dispersion stability was also investigated.
Machine learning approach for predicting Fusarium culmorum and F. proliferatum growth and mycotoxin production in treatments with ethylene-vinyl alco…
2020
Fusarium culmorum and F. proliferatum can grow and produce, respectively, zearalenone (ZEA) and fumonisins (FUM) in different points of the food chain. Application of antifungal chemicals to control these fungi and mycotoxins increases the risk of toxic residues in foods and feeds, and induces fungal resistances. In this study, a new and multidisciplinary approach based on the use of bioactive ethylene-vinyl alcohol copolymer (EVOH) films containing pure components of essential oils (EOCs) and machine learning (ML) methods is evaluated. Bioactive EVOH-EOC films were made incorporating cinnamaldehyde (CINHO), citral (CIT), isoeugenol (IEG) or linalool (LIN). Several ML methods (neural networ…
Influence of polymer molecular weight on in vitro dissolution behavior and in vivo performance of celecoxib:PVP amorphous solid dispersions
2016
In this study, the influence of the molecular weight of polyvinylpyrrolidone (PVP) on the non-sink in vitro dissolution and in vivo performance of celecoxib (CCX):PVP amorphous solid dispersions were investigated. The dissolution rate of CCX from the amorphous solid dispersions increased with decreasing PVP molecular weight and crystallization inhibition was increased with increasing molecular weight of PVP, but reached a maximum for PVP K30. This suggested that the crystallization inhibition was not proportional with molecular weight of the polymer, but rather there was an optimal molecular weight where the crystallization inhibition was strongest. Consistent with the findings from the non…
Effect of polymer type and drug dose on the in vitro and in vivo behavior of amorphous solid dispersions.
2016
This study investigated the non-sink in vitro dissolution behavior and in vivo performance in rats of celecoxib (CCX) amorphous solid dispersions with polyvinyl acetate (PVA), polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose (HPMC) at different drug doses. Both in vitro and in vivo, the amorphous solid dispersions with the hydrophilic polymers PVP and HPMC led to higher areas under both, the in vitro dissolution and the plasma concentration-time curves (AUC) compared to crystalline and amorphous CCX for all doses. In contrast, the amorphous solid dispersion with the hydrophobic polymer PVA showed a lower AUC both in vitro and in vivo than crystalline CCX. For crystalline CCX and…
Testing physiologic monitor alarm customization software to reduce alarm rates and improve nurses’ experience of alarms in a medical intensive care u…
2018
BACKGROUND:Clinicians in intensive care units experience alarm fatigue related to frequent false and non-actionable alarms produced by physiologic monitors. To reduce non-actionable alarms, alarm settings may need to be customized for individual patients; however, nurses may not customize alarms because of competing demands and alarm fatigue. OBJECTIVE:To examine the effectiveness and acceptance of physiologic monitor software to support customization of alarms. METHODS:This pre/post intervention study was conducted in a 56-bed medical intensive care unit. IntelliVue® Alarm Advisor customization support software for alarm limit violations was installed on all monitors and education on its u…
Management of nasal septal abscess in childhood: our experience.
2004
Summary A nasal septal abscess is usually the result of an infected hematoma of the septum. A secondary septal abscess may be the result of infections extending from any of the neighbouring tissues. The necrosis of septal cartilage may lead to nasal deformities and severe impairment of nasal patency and growth. Objectives: Assess if the drainage of the abscess and the immediate reconstruction of the destroyed nasal septum in the acute phase is the best treatment to prevent short- and long-term effect on nasal and midface growth. Methods: Three pediatric patients treated with drainage and immediate implantation of homologous bank cartilage prior to 1990 and four treated with mosaic plastic u…
Delayed and incomplete treatment may result in dural fistula development in children with Vein of Galen malformation
2017
The association of dural arteriovenous fistulas (DAVF) in children with Vein of Galen malformation (VGM) has recently been reported for the first time. In a larger series of cases treated with transarterial NBCA embolization, 30% had DAVF. We wanted to analyze the development of DAVF in our cohort of children with VGM and to evaluate whether their occurrence depends on different treatment timing and embolic materials. We analyzed 43 VGM cases treated with a combined transarterial and transvenous approach between 2003 and 2016. In our early series until 2011, we used coils solely in 21 children. Since 2012, 22 children were treated with the combination of coils and Onyx. In the early series…