Although most children with Hirschsprung disease ultimately do well, many experience a variety of ongoing problems after pull-through surgery. The most common include obstructive symptoms, soiling, ...enterocolitis and failure to thrive. The purpose of this guideline is to present a rational approach to the management of postoperative obstructive symptoms in children with Hirschsprung disease. The American Pediatric Surgical Association Board of Governors established a Hirschsprung Disease Interest Group. Group discussions, literature review and expert consensus were then used to summarize the current state of knowledge regarding causes, methods of diagnosis, and treatment approaches to children with obstructive symptoms following pull-through for Hirschsprung disease. Causes of obstructive symptoms post-pull-through include mechanical obstruction; persistent or acquired aganglionosis, hypoganglionosis, or transition zone pull-through; internal sphincter achalasia; disordered motility in the proximal intestine that contains ganglion cells; or functional megacolon caused by stool-holding behavior. An algorithm for the diagnosis and management of obstructive symptoms after a pull-through for Hirschsprung disease is presented. A stepwise, logical approach to the diagnosis and management of patients experiencing obstructive symptoms following pull-through for Hirschsprung disease can facilitate treatment.
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► PLA nanocomposites reinforced with cellulose were developed for packaging applications. ► The effect of cellulose modification and percentage in PLA nanocomposites was investigated. ► ...Surfactant-modified nanocrystals favour the cellulose dispersion in the PLA. ► Reductions of water permeability and good oxygen barrier properties were obtained. ► The overall migration level of PLA nanocomposites was below the normative limits.
The aim of this paper is to report the impact of the addition of cellulose nanocrystals on the barrier properties and on the migration behaviour of poly(lactic acid), PLA, based nano-biocomposites prepared by the solvent casting method. Their microstructure, crystallinity, barrier and overall migration properties were investigated. Pristine (CNC) and surfactant-modified cellulose nanocrystals (s-CNC) were used, and the effect of the cellulose modification and content in the nano-biocomposites was investigated.
The presence of surfactant on the nanocrystal surface favours the dispersion of CNC in the PLA matrix. Electron microscopy analysis shows the good dispersion of s-CNC in the nanoscale with well-defined single crystals indicating that the surfactant allowed a better interaction between the cellulose structures and the PLA matrix. Reductions of 34% in water permeability were obtained for the cast films containing 1wt.% of s-CNC while good oxygen barrier properties were detected for nano-biocomposites with both 1wt.% and 5wt.% of modified and un-modified cellulose nanocrystals, underlining the improvement provided by cellulose on the PLA films. Moreover, the migration level of the studied nano-biocomposites was below the overall migration limits required by the current normative for food packaging materials in both non-polar and polar simulants.
•PVA/Ch hydrogels with 1 and 3wt% of LNPs were prepared by freezing-thawing.•LNPs at 1wt% was beneficial in terms of thermal and mechanical performances.•LNPs promoted the crosslinking and limited ...the deswelling of PVA into the water.•LNPs was efficient in terms of antioxidative response, in synergism with chitosan.•Chitosan and LNPs were effective against E.coli and S.aureus bacteria strain.
Polyvinyl alcohol/chitosan (PVA/Ch) hydrogels containing 1 and 3wt% of lignin nanoparticles (LNPs) were prepared through a freezing-thaw procedure. Results from microstructural, thermal and mechanical characterization of LNPs based PVA/Ch demonstrated that the lowest amount of LNPs (1wt%) was beneficial, whereas the presence of agglomerates at higher LNP content limited the effect. Moreover, a different swelling behaviour was observed for hydrogels containing LNPs with respect of PVA/Ch, due to the formation of a porous honeycomb-like structure. A synergic effect of Ch and LNPs was revealed in terms of antioxidative response by DPPH (1,1-Diphenyl-2-picryl-hydrazyl) activity of migrated substances, whereas results from antimicrobial tests confirmed LNPs as effective against Gram negative bacteria (E. coli) when compared to Gram positive (S.aureus and S. epidermidis) strains. The obtained results suggested the possible use of produced PVA/Ch hydrogels incorporating LNPs in many different sectors, such as drug delivery, food packaging, wound dressing.
•Cellulose nanocrystals (CNC) were extracted from natural Phormium tenax and Flax.•CNC were also extracted from commercial microcrystalline cellulose for comparison.•Natural fibres offered high ...levels of extraction efficiency.•Homogeneous distribution of CNC in PVA is observed and transparent films are obtained.•CNC promotes the crystallization of the PVA matrix improving its plastic response.
PVA bio-nanocomposites reinforced with cellulose nanocrystals (CNC) extracted from commercial microcrystalline cellulose (MCC) and from two types of natural fibres, Phormium tenax and Flax of the Belinka variety, were produced by solvent casting in water. Morphological, thermal, mechanical and transparency properties were studied while the respective efficiency of the extraction process of CNC from the three sources was evaluated. The effect of CNC types and content on PVA properties and water absorption capacity were also evaluated. Natural fibres offered higher levels of extraction efficiency when compared with MCC hydrolysis yield. Thermal analysis proved that CNC promotes the crystallization of the PVA matrix, while improving its plastic response. It was also clarified that all PVA/CNC systems remain transparent due to CNC dispersion at the nanoscale, while being all saturated after the first 18–24h of water absorption.
In this study nanocrystalline cellulose (CNC)/graphene oxide (GO) composite films were prepared by drop casting water dispersion of GO in the presence of CNC and their nanostructures, surface and ...electrical properties were investigated. It was found that pristine hydrophilic GO presents a good dispersion when mixed with CNC along with a decrease of the composite electrical resistivity. The surface properties of the composite film indicated a poorer wettability with respect to that measured for separated materials. By applying an electric current through the CNC/GO composite a transition from an electrically insulating material to a conductive one was observed along with an improved wettability. The obtained results open an easy route for paper electronic based on the integration of nanocrystalline cellulose onto graphene devices.
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•Integration of nanocrystalline cellulose onto graphene based electronic devices.•Change of morphology and wettablity from separated to aggregated cellulose nanocrystals.•Change of conductivity when an electric current passes through the NCC/GO composite.
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•Cellulose nanocrystals (CNC) were isolated from Posidonia oceanica waste.•The surface of nanocrystals was also modified using a commercial surfactant (s-CNC).•Poly(lactic acid) (PLA) ...nanocomposites reinforced with CNC and s-CNC were developed.•The surfactant favours the CNC dispersion in the polymer supporting their effect on PLA properties.•PLA/cellulose systems can be used as new bio-nanocomposites in industrial applications.
Poly(lactic acid) (PLA) nanocomposite films, reinforced with cellulose nanocrystals (CNC) extracted from Posidonia oceanica plant waste, were produced by solvent casting and their morphological, mechanical, thermal, optical and migration properties were studied. Cellulose nanocrystals were successfully extracted through an optimized chemical treatment, followed by sulphuric acid hydrolysis. The nanocrystals were added to the neat polymer at two different weight percentages (1 and 3%wt) using a commercial surfactant to increase the dispersion of CNC in the biodegradable matrix. All the nanocomposites kept the optical transparency of the PLA matrix, while morphological investigations underlined the rougher fracture surfaces of the CNC based systems and a more porous structure of the PLA matrix, induced by the addition of surfactant modified s-CNC. The surfactant favours the cellulose nanocrystal dispersion in the polymer matrix, remarkably enhancing the nucleation effect for matrix crystallization and producing its plasticization. The migration levels for all the studied nanocomposites were well below the legislative limits required for their use as food packaging materials. The successful production of biodegradable nanocomposites incorporating cellulosic sources from biomass waste suggests the possibility of using these new bio-nanocomposites in industrial applications.
This research work aims at the compatibilization of poly(lactic acid)/poly(butylene adipate-co-terephthalate), PLA/PBAT binary blends by using cottonseed oil derivatives, i.e. epoxidized (ECSO) and ...maleinized (MCSO) cottonseed oil. The potential of these vegetable oil-based compatibilizers are compared versus the effects of a conventional styreneacrylic oligomer. The base PLA/PBAT binary blend composition was 80 wt% PLA/20 wt% PBAT and the amount of compatibilizer was set to 1 and 7.5 wt%. The effects of the different compatibilizers were evaluated on PLA/PBAT films in terms of mechanical and thermal properties as well as blend's morphology by field emission scanning electron microscopy (FESEM). Complementary, biodisintegration tests in controlled compost soil and surface properties were evaluated to assess the effects of the compatibilizers. Addition of 1 wt% ECSO and MCSO led to a remarkable increase in the elongation at break up to values over 100% with regard to neat PLA. Despite this, maximum elongation at break was obtained for the compatibilized PLA/PBAT blend with 7.5 wt% MCSO, reaching values of about 321.2% respect neat PLA keeping mechanical resistant properties, such as Young's modulus and tensile strength, at high levels. Therefore, vegetable oil-derived compatibilizers stand out as environmentally friendly additives for PLA/PBAT binary blends with improved properties.
Within the current economic situation, poverty indexes in developed countries are becoming more and more alarming. This makes the role of food banks very relevant, and in addition contributes towards ...reducing the problem of food waste. Motivated by the social importance of these non-profit organizations, this paper analyzes the impact of food banks on the supply chains to which they belong. Differences in the functioning of these supply chains are highlighted attending to the relations induced by the food banks. First, the international research background for this topic is summarized; then, the results of an empirical study in Spain are presented. Data were collected through surveys and analyzed using cluster methodology. Two different types of food bank were identified. These are described, characterized, and compared in terms of efficacy and efficiency.
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•Cellulose nanocrystals (CNC) were successfully extracted from Diss stems.•Chemical and enzymatic pretreated celluloses from Diss were acid hydrolyzed.•CNC from enzymatic treated ...fibres (E-CNC) exhibited enhanced thermal stability.•CNC from chemically treated fibres (C-CNC) have reduced size compared to E-CNC.
The aim of this research activity was based on the revalorization of Amplodesmos mauritanicus (Diss), an African grass largely presented in the Algerian territory. Diss stems were selected as native botanic material for the extraction of cellulose nanocrystals (CNC). Two different pretreatment steps were carried out to extract CNC from Amplodesmos mauritanicus stems and the following acidic hydrolysis procedure allowed to extract/obtain cellulose nanocrystals in aqueous suspension. The effect of the two different pretreatments, based essentially on chemical or enzymatic treatments, were deeply investigated and the properties compared. Field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were considered for the characterization of raw material, chemical or enzymatic treated Diss stems and CNC extracted from both chemical and enzymatic pretreated cellulose.
Evaluate the bispectral index (BIS) monitoring to detect delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH).
A single-center prospective study in patients with aSAH. BIS ...monitoring was recorded during 25–120 min in two periods, within the initial 72 h (BIS1) and between days 4 and 6 (BIS2) from admission. The median for each exported BIS parameter was analyzed. Transcranial Doppler (TCD) sonography was simultaneously performed with BIS1 (TCD1) and BIS2 (TCD2) monitoring. A multivariate logistic regression model was built to identify the variables associated with DCI.
Sixty-four patients were included and 16 (25%) developed DCI. During BIS2 monitoring, significant differences were found in BIS value (left, p = 0.01; right, p = 0.009), 95% spectral edge frequency (left and right, p = 0.04), and total power (left and right, p = 0.04). In multivariable analysis, vasospasm on TCD2 (OR 42.8 95% CI 3.1–573; p = 0.005), a median BIS2 value <85 in one or both sides (OR 6.2 95% CI 1.28–30; p = 0.023), and age (OR 1.08 95% CI 1.00–1.17; p = 0.04) were associated with the development of DCI.
BIS value is the most useful BIS parameter for detecting DCI after aSAH. Pending further validation, BIS monitoring might be even more accurate than TCD.
•BIS monitoring may help detect delayed cerebral ischemia after aneurysmal SAH.•A BIS value lesser than 85 in the right and/or left side was the best predictor.•BIS might be more accurate in the detection of clinical DCI than TCD.•Asymmetry index failed to detect delayed cerebral ischemia.
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