Electron-Beam-Induced Grafting Of Chitosan Onto HDPE/ATZ Composites for Biomedical Applications

HDPE and HDPE/ATZ surfaces were functionalised with chitosan Via electron-beam irradiation technique in order to prepare materials suitable for biomedical purposes. ATR–FTIR and wettability measurements were employed for monitoring the surface changes after both irradiation and chitosan grafting reaction. The presence of ATZ influenced both the EB irradiation process and the surface functionalisation. Mechanical properties of irradiated materials were not remarkably affected by irradiation processing. Biological assays indicated that electrostatic interactions between the negative charges of the surface of cell membranes and the –NH3+ sites on chitosan chains promoted cell adhesion, while some oxidized species produced during the irradiation process were thought to cause a detrimental effect on the cell Viability

Sulfate geoengineering impact on methane transport and lifetime: results from the Geoengineering Model Intercomparison Project (GeoMIP)

Abstract. Sulfate geoengineering (SG), made by sustained injection of SO2 in the tropical lower stratosphere, may impact the CH4 abundance through several photochemical mechanisms affecting tropospheric OH and hence the methane lifetime. (a) The reflection of incoming solar radiation increases the planetary albedo and cools the surface, with a tropospheric H2O decrease. (b) The tropospheric UV budget is upset by the additional aerosol scattering and stratospheric ozone changes: the net effect is meridionally not uniform, with a net decrease in the tropics, thus producing less tropospheric O(1D). (c) The extratropical downwelling motion from the lower stratosphere tends to increase the sulfate aerosol surface area density available for heterogeneous chemical reactions in the mid-to-upper troposphere, thus reducing the amount of NOx and O3 production. (d) The tropical lower stratosphere is warmed by solar and planetary radiation absorption by the aerosols. The heating rate perturbation is highly latitude dependent, producing a stronger meridional component of the Brewer–Dobson circulation. The net effect on tropospheric OH due to the enhanced stratosphere–troposphere exchange may be positive or negative depending on the net result of different superimposed species perturbations (CH4, NOy, O3, SO4) in the extratropical upper troposphere and lower stratosphere (UTLS). In addition, the atmospheric stabilization resulting from the tropospheric cooling and lower stratospheric warming favors an additional decrease of the UTLS extratropical CH4 by lowering the horizontal eddy mixing. Two climate–chemistry coupled models are used to explore the above radiative, chemical and dynamical mechanisms affecting CH4 transport and lifetime (ULAQ-CCM and GEOSCCM). The CH4 lifetime may become significantly longer (by approximately 16 %) with a sustained injection of 8 Tg-SO2 yr−1 starting in the year 2020, which implies an increase of tropospheric CH4 (200 ppbv) and a positive indirect radiative forcing of sulfate geoengineering due to CH4 changes (+0.10 W m−2 in the 2040–2049 decade and +0.15 W m−2 in the 2060–2069 decade)

Radiative forcing from aircraft emissions of NOx: model calculations with CH4 surface flux boundary condition

© 2017 The authors. Two independent chemistry-transport models with troposphere-stratosphere coupling are used to quantify the different components of the radiative forcing (RF) from aircraft emissions of NO x , i.e., the University of L'Aquila climate-chemistry model (ULAQ-CCM) and the University of Oslo chemistry-transport model (Oslo-CTM3). The tropospheric NO x enhancement due to aircraft emissions produces a short-term O 3 increase with a positive RF (+17.3mW/m 2 ) (as an average value of the two models). This is partly compensated by the CH 4 decrease due to the OH enhancement (-9.4mW/m 2 ). The latter is a long-term response calculated using a surface CH 4 flux boundary condition (FBC), with at least 50 years needed for the atmospheric CH 4 to reach steady state. The radiative balance is also affected by the decreasing amount of CO 2 produced at the end of the CH 4 oxidation chain: an average CO 2 accumulation change of -2.2 ppbv/yr is calculated on a 50 year time horizon (-1.6mW/m 2 ). The aviation perturbed amount of CH 4 induces a long-term response of tropospheric O 3 mostly due to less HO 2 and CH 3 O 2 being available for O 3 production, compared with the reference case where a constant CH 4 surface mixing ratio boundary condition is used (MBC) (-3.9mW/m 2 ). The CH 4 decrease induces a long-term response of stratospheric H2O (-1.4mW/m 2 ). The latter finally perturbs HO x and NO x in the stratosphere, with a more efficient NO x cycle for mid-stratospheric O 3 depletion and a decreased O 3 production from HO 2 +NO in the lower stratosphere. This produces a long-term stratospheric O 3 loss, with a negative RF (-1.2mW/m 2 ), compared with the CH 4 MBC case. Other contributions to the net NO x RF are those due to NO 2 absorption of UV-A and aerosol perturbations (the latter calculated only in the ULAQ-CCM). These comprise: increasing sulfate due to more efficient oxidation of SO 2 , increasing inorganic and organic nitrates and the net aerosols indirect effect on warm clouds. According to these model calculations, aviation NO x emissions for 2006 produced globally a net cooling effect of -5.7mW/m 2 (-6.2 and -5.1mW/m 2 , from ULAQ and Oslo models, respectively). When the effects of aviation sulfur emissions are taken into account in the atmospheric NO x balance (via heterogeneous chemistry), the model-average net cooling effects of aviation NO x increases to -6.2mW/m 2 . Our study applies to a sustained and constant aviation NO x emission and for the given background NOy conditions. The perturbation picture, however, may look different if an increasing trend in aviation NO x emissions would be allowed

Influence of chitosan on the mechanical and biological properties of HDPE for biomedical applications

High density polyethylene (HDPE) is widely used in biomedical field, except when strong cell-material interactions and high mechanical properties are required. To address this pitfall, two kinds of chitosan in different amounts were used as filler in the present research. Composites were prepared by melt extrusion process and their microstructural, thermal and mechanical properties were widely investigated. Also roughness and wettability were studied, as features of paramount importance in dictating cell response. Both types of chitosan endowed HDPE with higher Young modulus and lower elongation at break. Interestingly, fibroblast adhesion and viability were enhanced when a low amount of filler was used. The interaction of HDPE/chitosan composites with biological environment was investigated for the first time in order to assess the feasibility of these composites as materials for biomedical application

Case Report: Atypical psychotic onset of type I Arnold-Chiari malformation

Introduction: We report a case of type I Arnold-Chiari malformation that is very peculiar because of its particular onset especially characterized by psychiatric symptoms. These symptoms were so prevailing that, for fifteen years, they masked the neurological aspects and the patient was treated with high doses of psychotropic drugs without any benefit. If the Arnold-Chiari malformation had been diagnosed before the development of severe hydro-syringomyelia, the patient could have underwent decompressive neurosurgery which may have improved her quality of life. It is worthwhile to highlight that psychotic symptoms may be caused by this congenital malformation, that typically has an aspecific onset. Therefore it\u2019s important to consider an eventual organic etiology while challenging a resistant clinical picture with unusual presentation. Case description: A 51-year-old woman reported neurological symptoms consisting of headaches, blurred vision, diplopia, tinnitus, vertigo and psychiatric symptoms including obsessive ideas about the fear of killing her son, auditory and visual pseudo-hallucinations. The symptoms had developed suddenly at the age of 35 years and persisted thereafter. She underwent multiple hospitalizations in psychiatric units and was treated with a variety of psychopharmacological approaches without substantial improvement. We performed a brain MRI that identified a type I Arnold-Chiari malformation. We assessed psychiatric symptoms using the Structured Clinical Interview for DSM IV Axis I Disorders, the Brief Psychiatric Rating Scale, and the Yale-Brown Obsessive-Compulsive Scale. A tailored psychopharmacological therapy led to a partial improvement in mood and anxiety but not in hallucinations. Discussion: We want to highlight how important is, in everyday psychiatric clinical practice, not to focus only on psychiatric aspects but consider the patient globally, because in this case psychiatric problems were the onset presentation of a rare neurological syndrome