453 research outputs found

    Space-time clustering analyses of childhood acute lymphoblastic leukaemia by immunophenotype

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    Space-time clustering analyses of acute lymphoblastic leukaemia in children, by immunophenotype, were carried out using a population-based registry. Significant evidence was found of space-time clustering for cases of the precursor B-cell sub-type, in the childhood peak, based on time and location at birth

    Non-melt selective enhancement of crystalline structure in molybdenum thin films using femtosecond laser pulses

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    It is challenging to crystalize a thin film of higher melting temperature when deposited on a substrate with comparatively lower melting point. Trading such disparities in thermal properties between a thin film and its substrate can significantly impede material processing. We report a novel solid-state crystallization process for annealing of high melting point molybdenum thin films. A systematic investigation of laser induced annealing from single pulse to high pulse overlapping is reported upon scanning at fluences lower than the threshold required for the damage/ablation of molybdenum thin films. The approach allows better control of the grain size by changing the applied laser fluence. Atomic force microscopy surface morphology and x-ray diffraction (XRD) analysis reveal significant improvements in the average polycrystalline grain size after laser annealing; the sheet resistance was reduced by 19% of the initial value measured by a Four-point probe system. XRD confirms the enlargement of the single crystal grain size. No melting was evident, although a change in the close packing, shape and size of nanoscale polycrystalline grains is observed. Ultrashort laser induced crystallinity greatly enhances the electrical properties; Hall measurements reinforced that the overall carrier concentration increases after scanning at different laser fluences. The proposed method, based on the aggregation and subsequent growth of polycrystalline and single crystal-grains, leading to enhanced crystallization, has potential to be applicable in thin film processing industry for their wide applications

    Characteristics of starch-based films plasticised by glycerol and by the ionic liquid 1-ethyl-3-methylimidazolium acetate: A comparative study

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    This paper reports the plasticisation effect of the ionic liquid, 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]), as compared with the traditionally used plasticiser, glycerol, on the characteristics of starch-based films. For minimising the additional effect of processing, a simple compression moulding process (which involves minimal shear) was used for preparation of starch-based films. The results show that [Emim][OAc] was favourable for plasticisation, i.e., disruption of starch granules (by scanning electron microscopy), and could result in a more amorphous structure in the starch-based materials (by X-ray diffraction and dynamic mechanical analysis). 13C CP/MAS and SPE/MAS NMR spectroscopy revealed that not only was the crystallinity reduced by [Emim][OAc], but also the amorphous starch present was plasticised to a more mobile form as indicated by the appearance of amorphous starch in the SPE/MAS spectrum. Mechanical results illustrate that, when either glycerol or [Emim][OAc] was used, a higher plasticiser content could contribute to higher flexibility. In spite of the accelerated thermal degradation of starch by [Emim][OAc] as shown by thermogravimetric analysis, the biodegradation study revealed the antimicrobial effect of [Emim][OAc] on the starch-based materials. Considering the high-amylose starch used here which is typically difficult to gelatinise in a traditional plasticiser (water and/or glycerol), [Emim][OAc] is demonstrated to be a promising plasticiser for starch to develop “green” flexible antimicrobial materials for novel applications

    Optimization of Suture-Free Laser-Assisted Vessel Repair by Solder-Doped Electrospun Poly(ε-caprolactone) Scaffold

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    Poor welding strength constitutes an obstacle in the clinical employment of laser-assisted vascular repair (LAVR) and anastomosis. We therefore investigated the feasibility of using electrospun poly(ε-caprolactone) (PCL) scaffold as reinforcement material in LAVR of medium-sized vessels. In vitro solder-doped scaffold LAVR (ssLAVR) was performed on porcine carotid arteries or abdominal aortas using a 670-nm diode laser, a solder composed of 50% bovine serum albumin and 0.5% methylene blue, and electrospun PCL scaffolds. The correlation between leaking point pressures (LPPs) and arterial diameter, the extent of thermal damage, structural and mechanical alterations of the scaffold following ssLAVR, and the weak point were investigated. A strong negative correlation existed between LPP and vessel diameter, albeit LPP (484 ± 111 mmHg) remained well above pathophysiological pressures. Histological analysis revealed that thermal damage extended into the medial layer with a well-preserved internal elastic lamina and endothelial cells. Laser irradiation of PCL fibers and coagulation of solder material resulted in a strong and stiff scaffold. The weak point of the ssLAVR modality was predominantly characterized by cohesive failure. In conclusion, ssLAVR produced supraphysiological LPPs and limited tissue damage. Despite heat-induced structural/mechanical alterations of the scaffold, PCL is a suitable polymer for weld reinforcement in medium-sized vessel ssLAVR

    Spatial quantitation of drugs in tissues using liquid extraction surface analysis mass spectrometry imaging

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    Liquid extraction surface analysis mass spectrometry imaging (LESA-MSI) has been shown to be an effective tissue profiling and imaging technique, producing robust and reliable qualitative distribution images of an analyte or analytes in tissue sections. Here, we expand the use of LESA-MSI beyond qualitative analysis to a quantitative analytical technique by employing a mimetic tissue model previously shown to be applicable for MALDI-MSI quantitation. Liver homogenate was used to generate a viable and molecularly relevant control matrix for spiked drug standards which can be frozen, sectioned and subsequently analyzed for the generation of calibration curves to quantify unknown tissue section samples. The effects of extraction solvent composition, tissue thickness and solvent/tissue contact time were explored prior to any quantitative studies in order to optimize the LESA-MSI method across several different chemical entities. The use of a internal standard to normalize regional differences in ionization response across tissue sections was also investigated. Data are presented comparing quantitative results generated by LESA-MSI to LC-MS/MS. Subsequent analysis of adjacent tissue sections using DESI-MSI is also reported

    Evaluating a selective prevention programme for binge drinking among young adolescents: study protocol of a randomized controlled trial

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    Contains fulltext : 99319.pdf (publisher's version ) (Open Access)Background In comparison to other Europe countries, Dutch adolescents are at the top in drinking frequency and binge drinking. A total of 75% of the Dutch 12 to 16 year olds who drink alcohol also engage in binge drinking. A prevention programme called Preventure was developed in Canada to prevent adolescents from binge drinking. This article describes a study that aims to assess the effects of this selective school-based prevention programme in the Netherlands. Methods A randomized controlled trial is being conducted among 13 to 15-year-old adolescents in secondary schools. Schools were randomly assigned to the intervention and control conditions. The intervention condition consisted of two 90 minute group sessions, carried out at the participants' schools and provided by a qualified counsellor and a co-facilitator. The intervention targeted young adolescents who demonstrated personality risk for alcohol abuse. The group sessions were adapted to four personality profiles. The control condition received no further intervention above the standard substance use education sessions provided in the Dutch national curriculum. The primary outcomes will be the percentage reduction in binge drinking, weekly drinking and drinking-related problems after three specified time periods. A screening survey collected data by means of an Internet questionnaire. Students have completed, or will complete, a post-treatment survey after 2, 6, and 12 months, also by means of an online questionnaire. Discussion This study protocol presents the design and current implementation of a randomized controlled trial to evaluate the effectiveness of a selective alcohol prevention programme. We expect that a significantly lower number of adolescents will binge drink, drink weekly, and have drinking-related problems in the intervention condition compared to the control condition, as a result of this intervention.9 p
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