New perspectives for neutron imaging through advanced event-mode data acquisition.

Imaging using scintillators is a widespread and cost-effective approach in radiography. While different types of scintillator and sensor configurations exist, it can be stated that the detection efficiency and resolution of a scintillator-based system strongly depend on the scintillator material and its thickness. Recently developed event-driven detectors are capable of registering spots of light emitted by the scintillator after a particle interaction, allowing to reconstruct the Center-of-Mass of the interaction within the scintillator. This results in a more precise location of the event and therefore provides a pathway to overcome the scintillator thickness limitation and increase the effective spatial resolution of the system. Utilizing this principle, we present a detector capable of Time-of-Flight imaging with an adjustable field-of-view, ad-hoc binning and re-binning of data based on the requirements of the experiment including the possibility of particle discrimination via the analysis of the event shape in space and time. It is considered that this novel concept might replace regular cameras in neutron imaging detectors as it provides superior detection capabilities with the most recent results providing an increase by a factor 3 in image resolution and an increase by up to a factor of 7.5 in signal-to-noise for thermal neutron imaging.

Chasing quantitative biases in neutron imaging with scintillator-camera detectors: a practical method with black body grids.

We propose a method for improving the quantification of neutron imaging measurements with scintillator-camera based detectors by correcting for systematic biases introduced by scattered neutrons and other sources such as light reflections in the detector system. This method is fully experimental, using reference measurements with a grid of small black bodies (BB) to measure the bias contributions directly. Using two test samples, one made of lead alloy and having a moderate (20%) neutron transmission and one made of stainless-steel and having a very low (1%) transmission, we evaluated the improvement brought by this method in reducing both the average quantification bias and the uncertainty around this average bias after tomographic reconstruction. The results show that a reduction of the quantification bias of up to one order of magnitude can be obtained. For moderately transparent samples, little sensitivity is observed to the parameters used for the correction. For the more challenging sample with very low transmission, a correct placement of the BB grid is of utmost importance for a successful correction.

A Monte Carlo approach for scattering correction towards quantitative neutron imaging of polycrystals.

The development of neutron imaging from a qualitative inspection tool towards a quantitative technique in materials science has increased the requirements for accuracy significantly. Quantifying the thickness or the density of polycrystalline samples with high accuracy using neutron imaging has two main problems: (i) the scattering from the sample creates artefacts on the image and (ii) there is a lack of specific reference attenuation coefficients. This work presents experimental and simulation results to explain and approach these problems. Firstly, a series of neutron radiography and tomography experiments of iron, copper and vanadium are performed and serve as a reference. These materials were selected because they attenuate neutrons mainly through coherent (Fe and Cu) and incoherent (V) scattering. Secondly, an ad hoc Monte Carlo model was developed, based on beamline, sample and detector parameters, in order to simulate experiments, understand the physics involved and interpret the experimental data. The model, developed in the McStas framework, uses a priori information about the sample geometry and crystalline structure, as well as beamline settings, such as spectrum, geometry and detector type. The validity of the simulations is then verified with experimental results for the two problems that motivated this work: (i) the scattering distribution in transmission imaging and (ii) the calculated attenuation coefficients.

Unlocking high spatial resolution in neutron imaging through an add-on fibre optics taper.

The demand for high resolution neutron imaging has been steadily increasing over the past years. The number of facilities offering cutting edge resolution is however limited, due to (i) the design complexity of an optimized device able to reach a resolution in the order of ≈ 10 µm and (ii) limitations in available neutron flux. Here we propose a simple addition, based on a Fibre Optics Taper (FOT), that can be easily attached to an already existing scintillator-camera imaging detector in order to efficiently increase its spatial resolution and hence boost the capability of an instrument into high resolution applications.

Statistical uncertainty in the dark-field and transmission signal of grating interferometry.

We present a framework to estimate the fundamental statistical uncertainty of grating interferometer experiments based on a Monte-Carlo method. Using the framework, we are able to determine the uncertainty of individual measurements as well as suggesting experimental protocols that minimise the statistical uncertainty for given overall exposure times. The method presented here is valid for both X-rays and neutrons and can be generalised for any modulation measurement.

Mineral inadequacy of oral diets offered to patients in a Brazilian hospital.

INTRODUCTION: While enteral diets for hospitalized patients normally follow nutrient composition guidelines, more than 90% of hospitalized patients receive oral diets with unknown mineral composition. OBJECTIVE: To evaluate the mineral contents and adequacy of three types of oral diets (regular, blend and soft) and complementary snacks offered to patients of a Brazilian hospital. METHODS: The amount of minerals was determined in two non-consecutive days in duplicate samples of breakfast, collation, lunch, snack, dinner, supper and a complementary snack meal. Dietary Reference Intakes (DRIs) were used to determine the adequacy of the daily amounts served to patients. RESULTS AND DISCUSSION: The regular diet met the RDA (Recommended Dietary Allowances) requirements only for Mn, P and Se, while the blend diet was deficient in Ca, K and Mg, and the soft diet met RDA requirements only for P and Zn. Iron was below the RDA requirement in all diets for women in fertile age, and Na was above the safe limit of intake (UL) in all the diets. The use of complementary snack was effective in meeting RDA requirements for Cu in the regular diet, and Mn and Se in the soft diet, but promoted overconsumption of Na. CONCLUSIONS: Evident nutritional imbalances have been detected at a key interphase between nutrition and public health services, but a solution does not appear to be insurmountable. A permanent nutritional evaluation of hospital oral diets should be an integral part of routine health care in order to speed the recovery of the hospitalized patient and dispel eventual risks due to critical mineral imbalances.

Physico-chemical and sensory properties of reduced-fat mortadella prepared with blends of calcium, magnesium and potassium chloride as partial substitutes for sodium chloride.

Blends of calcium, magnesium and potassium chloride were used to partially replace sodium chloride (50-75%) in reduced-fat mortadella formulations. The presence of calcium chloride reduced the emulsion stability, cooking yield, elasticity and cohesiveness and increased hardness; however, it yielded the best sensory acceptance when 50% NaCl was replaced by 25% CaCl(2) and 25% KCl. There was no effect of the salt substitutes on mortadella color, appearance and aroma. All salt combinations studied showed stable lipid oxidation during its shelf life. The use of a blend with 1% NaCl, 0.5% KCl and 0.5% MgCl(2) resulted in the best emulsion stability, but the worst scores for flavor. This study suggests that it is possible to reduce the sodium chloride concentration by 50% in reduced-fat mortadella using the studied salt combinations with necessary adjustments to optimize the sensory properties (MgCl(2) 25%; KCl 25%) or emulsion stability (CaCl(2) 25%; KCl 25%).

Correlação entre a atividade sérica da ceruloplasmina e os teores sérico e hepático de cobre em novilhas Nelore / Ceruloplasmin serum activity correlation with copper serum and liver concentrations in Nelore heifers

Avaliou-se a atividade oxidativa sérica da ceruloplasmina como indicadora dos teores sérico e hepático de cobre e compararam-se dois métodos de determinação da ceruloplasmina, pelo parafenileno e pela ortodianisidina. Foram colhidas 56 amostras de soro e de fígado (biópsias hepáticas) de novilhas Nelore para determinação da atividade sérica da ceruloplasmina e da concentração de cobre. As correlações entre a concentração sérica de cobre e a atividade sérica da ceruloplasmina determinadas pelos métodos do parafemileno e da ortodianisidina foram 0,75 e 0,62, respectivamente. As correlações entre a concentração hepática de cobre e a atividade sérica da ceruloplasmina pelos métodos citados foram 0,15 e 0,12. Não foi observada correlação entre os valores séricos e hepáticos de cobre. A correlação entre determinação da atividade sérica de ceruloplasmina, que utilizou o parafenileno como substrato, e o cobre sérico foi maior do que a correlação entre esse mineral e o método que usou a ortodianisidina.

Soapstone (steatite) cookware as a source of minerals.

Steatite or soapstone, is a soft metamorphic rock composed mainly of talc, dolomite and actinolite, which is abundantly found and used for the manufacture of cookware in south-east Brazil. The study estimates its usage for cookware among dwellers of Ouro Preto, and assesses the possible toxicological or nutritional impact on food preparation. Pans made of steatite were purchased both in the crude (n = 6) and 'cured'forms (n = 6). Migration of Ca, Fe, Mg, Mn, Co, Al, Cr, Ni, Pb and Cd was determined for 20 sequential cooking trials, using 3 and 5% acetic acid as a food simulant. Analytical determinations were carried out by inductively coupled plasma atomic-emission spectrometry and the data treated by an individual model of random effects, simple linear regression and Pearson's correlation. About 81% of Ouro Preto's native population own soapstone cookware and, of these, 79% use the pans regularly. Mineral migration followed the general solubility of the crystalline components of the rock. Therefore, Ca, Mg, Fe and Mn were, in that order, the elements that exhibited highest migration, whereas the remaining were seen in negligible levels, except for Ni in the crude pans. The 5% solution favoured migration, whereas curing tended to restrict migration and extend durability of the pan. It is concluded that while cured soapstone pans do not offer mineral toxicity, they may contribute to the mineral nutrition of human beings.

Erythrocyte sodium-lithium countertransport and proliferative diabetic retinopathy.

PURPOSE: To investigate whether elevated erythrocyte Na+/Li+ countertransport (Na+/Li+ CT) activity is present in patients with proliferative diabetic retinopathy (PDR). METHODS: The rate of Na+/Li+ CT activity assayed in 21 patients with type 1 diabetes mellitus (DM) presenting PDR was compared with 10 patients with nonproliferative retinopathy (NPDR) and with 11 patients with normal fundi. Twelve normal volunteers with no family history of hypertension were used as a control group. The albumin excretion rate was determined by nephelometry, and the glomerular filtration rate was measured by the plasma clearance of eidetic acid labeled with chromium-51. RESULTS: Patients with PDR showed higher diastolic blood pressure levels (mean +/- SD) compared with those with NPDR or normal fundi (95 +/- 13 versus 90 +/- 09 and 82 +/- 19 mm Hg, P = 0.02, respectively). The albumin excretion rate was higher [geometric mean (range)], and the glomerular filtration rate was lower (mean +/- SD) in patients with PDR than in those with NPDR or normal fundi [333 (2 to 5140) versus 32 (5.9 to 2200) and 6 (1.5 to 306) microg/min, P = 0.01, and 63 +/- 33 versus 99 +/- 37 and 93 +/- 43 ml/min, P = 0.02, respectively]. The mean Na+/Li+ CT in patients with PDR was significantly higher than in patients with NPDR or normal fundi and control group (0.46 +/-0.20 versus 0.32 +/- 0.12, 0.32 +/- 11, and 0.21 +/- 0.07 mM/L red blood cells (RBC)/h, respectively, P = 0.0001). In a multiple logistic regression analysis, with PDR as the dependent variable, Na+/Li+ CT (odds ratio [OR]: 4.7, confidence interval [CI]: 1.2-17.6, P = 0.02), diastolic blood pressure (OR, 3.4; CI, 1.3 to 9.6; P = 0.018), and glomerular filtration rate (OR, 5.1; CI, 1.6-17.7; P = 0.007) were the only variables that were maintained in the equation, indicating that they were the main determinants of PDR. CONCLUSIONS: Patients with type 1 DM and proliferative retinopathy have elevated erythrocyte Na+/Li+ CT.