CFD simulations of RTD of a strawberry pulp in a continuous ohmic heater

A pilot ohmic heater is to be tested for the continuous aseptic processing of strawberry pulps and jams. The hydrodynamics and the fluid residence time distribution (RTD) have been experimentally investigated for Newtonian and non-Newtonian fluids (water and an industrial strawberry pulp, respectively), for several inlet flow rates. The results were obtained using Computational Fluid Dynamics (CFD) with a user-defined function (UDF) description of the fluid phase (pulp). For all of the conditions tested the fluid phase is described using the laminar flow model. The results show that the RTD is affected by the inlet flow rate but not so significantly by the process temperature. Some shortcuts and dead zones were detected in the ohmic heater specially for Newtonian fluids. The heater behaves like a piston flow with longitudinal mixing

Aseptic processing of a strawberry pulp in a continuous ohmic heater: numerical simulations and model validation

Continuous food-sterilization processes often involve the flow of liquids or solid-liquid mixtures, frequently highly viscous and with non-Newtonian behaviour, in pipes and reactors. Heat treatment of such flows is complex and it is necessary to guarantee that each part of the material is adequately processed, preventing overcooking as much as possible. The use of ohmic heating technology as an alternative heating method has regained interest for complex fluids or multiphase foods

Numerical simulations of the hydrodynamic behaviour of a continuous ohmic heater operating with Newtonian and Non-Newtonian fluids

A pilot ohmic heater was tested for the continuous aseptic processing of strawberry pulp. The fluid mechanics and the fluid residence time distribution (RTD), in the whole volume of the vessel and exclusively in the heating zone (between the electrodes), have been numerically simulated using Computational Fluid Dynamics (Fluent™) for a Newtonian (water) and a non-Newtonian fluid (strawberry pulp). These simulations were performed at different mass flow rates (from 0.5 to 2 kg/min.) and different inlet temperatures (from 40 to 90 ºC). RTDs were determined defining a unit scalar at the inlet and monitoring its value at the outlet. These results allowed the construction of F-diagrams and the calculation of the hold back (H) and segregation (S). The simulations showed that for 0.5 kg/min water induces the formation of more shortcuts (10 % higher H) then pulp. However, for 2 kg/min both fluids display a similar behaviour (less than 3 % difference between H values). Furthermore, RTD is affected by the inlet mass flow rate but not so significantly by process temperature. The values of S calculated for water show that the reactor approaches plug flow behaviour. The RTD determinations in the heating zone allowed the establishment of an equation for the prediction of the outlet temperature of the fluid, allowing setting criteria for the aseptic processing of fluids thus guaranteeing the microbiological safety of the products

Simulações numéricas do processamento asséptico de polpas de morango num aquecedor óhmico contínuo

Neste trabalho efectuaram-se simulações numéricas dos padrões de fluxo num aquecedor óhmico contínuo, em estado estacionário, com recurso ao programa Fluent™. Para tal, criou-se uma grelha hexagonal (não estruturada) com base na geometria do aquecedor óhmico. A precisão dos resultados simulados foi optimisada através da diminuição do espaçamento entre as células junto às paredes. O número total de células na grelha foi minimizado por aplicação de uma condição de simetria axial (378 348 células). Para um fluido newtoniano (água) e um outro não newtoniano (polpa de morango) simularam-se diversas condições de escoamento, correspondendo a valores do número de Reynolds (Re) inferiores a 2000 (regime de escoamento laminar). Para a simulação com polpa de morango foi necessário determinar experimentalmente a dependência da viscosidade com a temperatura, cujo efeito foi expresso num modelo reológico do tipo “plástico de Bingham”. Após obter os padrões de fluxo no interior do aquecedor, calculou-se a distribuição dos tempos de residência (DTR) do fluido em todo o seu volume. Recorrendo à DTR exclusivamente na zona de aquecimento (entre os eléctrodos) foi possível prever o perfil térmico do fluido tratado no final da etapa de aquecimento. Consequentemente, obteve-se uma equação de projecto que relaciona a temperatura final com as variáveis operacionais (caudal de fluido, voltagem aplicada e tipo de fluido), conseguindo-se optimizar as condições de operação do aquecedor óhmicode acordo com a segurança microbiológica dos produtos processados e na minimização dos gastos energéticos. No final do estudo concluiu-se que a aplicação deste aquecedor às polpas de morango está limitada a caudais máximos de 2 kg/min e voltagens mínimas de 100 V

Overexpression of platelet-derived growth factor receptor α in breast cancer is associated with tumour progression

INTRODUCTION: Receptor tyrosine kinases have been extensively studied owing to their frequently abnormal activation in the development and progression of human cancers. Platelet-derived growth factor receptors (PDGFRs) are receptors with intrinsic tyrosine kinase activity that regulate several functions in normal cells and are widely expressed in a variety of malignancies. After the demonstration that gastrointestinal stromal tumours without c-Kit mutations harbour PDGFR-α-activating mutations and that PDGFR-α is also a therapeutic target for imatinib mesylate, the interest for this receptor has increased considerably. Because breast cancer is one of the most frequent neoplasias in women worldwide, and only one study has reported PDGFR-α expression in breast carcinomas, the aim of this work was to investigate the potential significance of PDGFR-α expression in invasive mammary carcinomas. METHODS: We used immunohistochemistry to detect PDGFR-α overexpression on a series of 181 formalin-fixed paraffin-embedded invasive ductal breast carcinomas and in two breast cancer cell lines: MCF-7 and HS578T. We associated its expression with known prognostic factors and we also performed polymerase chain reaction–single-stranded conformational polymorphism and direct sequencing to screen for PDGFR-α mutations. RESULTS: PDGFR-α expression was observed in 39.2% of the breast carcinomas and showed an association with lymph node metastasis (P = 0.0079), HER-2 expression (P = 0.0265) and Bcl2 expression (P = 0.0121). A correlation was also found with the expression of platelet-derived growth factor A (PDGF-A; P = 0.0194). The two cell lines tested did not express PDGFR-α. Screening for mutations revealed alterations in the PDGFR-α gene at the following locations: 2500A→G, 2529T→A and 2472C→T in exon 18 and 1701G→A in exon 12. We also found an intronic insertion IVS17-50insA at exon 18 in all sequenced cases. None of these genetic alterations was correlated with PDGFR-α expression. The cell lines did not reveal any alterations in the PDGFR-α gene sequence. CONCLUSION: PDGFR-α is expressed in invasive breast carcinomas and is associated with biological aggressiveness. The genetic alterations described were not correlated with protein expression, but other mechanisms such as gene amplification or constitutive activation of a signalling pathway inducing this receptor could still sustain PDGFR-α as a potential therapeutic target

Benign follicular tumors

Benign follicular tumors comprise a large and heterogeneous group of neoplasms that share a common histogenesis and display morphological features resembling one or several portions of the normal hair follicle, or recapitulate part of its embryological development. Most cases present it as clinically nondescript single lesions and essentially of dermatological relevance. Occasionally, however, these lesions be multiple and represent a cutaneous marker of complex syndromes associated with an increased risk of visceral neoplasms. In this article, the authors present the microscopic structure of the normal hair follicle as a basis to understand the type and level of differentiation of the various follicular tumors. The main clinicopathological features and differential diagnosis of benign follicular tumors are then discussed, including dilated pore of Winer, pilar sheath acanthoma, trichoadenoma, trichilemmoma, infundibuloma, proliferating trichilemmal cyst/tumor, trichoblastoma and its variants, pilomatricoma, trichodiscoma/fibrofolliculoma, neurofollicular hamartoma and trichofolliculoma. In addition, the main syndromes presenting with multiple follicular tumors are also discussed, namely Cowden, Birt-Hogg-Dubé, Rombo and Bazex-Dupré-Christol syndromes, as well as multiple tumors of follicular infundibulum (infundibulomatosis) and multiple trichoepitheliomas. Although the diagnosis of follicular tumors relies on histological examination, we highlight the importance of their knowledge for the clinician, especially when in presence of patients with multiple lesions that may be the cutaneous marker of a cancer-prone syndrome. The dermatologist is therefore in a privileged position to recognize these lesions, which is extremely important to provide further propedeutic, appropriate referral and genetic counseling for these patients.info:eu-repo/semantics/publishedVersio

Implicit sequence learning is preserved in dyslexic children

This study investigates the implicit sequence learning abilities of dyslexic children using an artificial grammar learning task with an extended exposure period. Twenty children with developmental dyslexia participated in the study and were matched with two control groups-one matched for age and other for reading skills. During 3 days, all participants performed an acquisition task, where they were exposed to colored geometrical forms sequences with an underlying grammatical structure. On the last day, after the acquisition task, participants were tested in a grammaticality classification task. Implicit sequence learning was present in dyslexic children, as well as in both control groups, and no differences between groups were observed. These results suggest that implicit learning deficits per se cannot explain the characteristic reading difficulties of the dyslexics.info:eu-repo/semantics/publishedVersio

Alcohol use and burden for 195 countries and territories, 1990-2016 : a systematic analysis for the Global Burden of Disease Study 2016

Background Alcohol use is a leading risk factor for death and disability, but its overall association with health remains complex given the possible protective effects of moderate alcohol consumption on some conditions. With our comprehensive approach to health accounting within the Global Burden of Diseases, Injuries, and Risk Factors Study 2016, we generated improved estimates of alcohol use and alcohol-attributable deaths and disability-adjusted life-years (DALYs) for 195 locations from 1990 to 2016, for both sexes and for 5-year age groups between the ages of 15 years and 95 years and older. Methods Using 694 data sources of individual and population-level alcohol consumption, along with 592 prospective and retrospective studies on the risk of alcohol use, we produced estimates of the prevalence of current drinking, abstention, the distribution of alcohol consumption among current drinkers in standard drinks daily (defined as 10 g of pure ethyl alcohol), and alcohol-attributable deaths and DALYs. We made several methodological improvements compared with previous estimates: first, we adjusted alcohol sales estimates to take into account tourist and unrecorded consumption; second, we did a new meta-analysis of relative risks for 23 health outcomes associated with alcohol use; and third, we developed a new method to quantify the level of alcohol consumption that minimises the overall risk to individual health. Findings Globally, alcohol use was the seventh leading risk factor for both deaths and DALYs in 2016, accounting for 2.2% (95% uncertainty interval [UI] 1.5-3.0) of age-standardised female deaths and 6.8% (5.8-8.0) of age-standardised male deaths. Among the population aged 15-49 years, alcohol use was the leading risk factor globally in 2016, with 3.8% (95% UI 3.2-4-3) of female deaths and 12.2% (10.8-13-6) of male deaths attributable to alcohol use. For the population aged 15-49 years, female attributable DALYs were 2.3% (95% UI 2.0-2.6) and male attributable DALYs were 8.9% (7.8-9.9). The three leading causes of attributable deaths in this age group were tuberculosis (1.4% [95% UI 1. 0-1. 7] of total deaths), road injuries (1.2% [0.7-1.9]), and self-harm (1.1% [0.6-1.5]). For populations aged 50 years and older, cancers accounted for a large proportion of total alcohol-attributable deaths in 2016, constituting 27.1% (95% UI 21.2-33.3) of total alcohol-attributable female deaths and 18.9% (15.3-22.6) of male deaths. The level of alcohol consumption that minimised harm across health outcomes was zero (95% UI 0.0-0.8) standard drinks per week. Interpretation Alcohol use is a leading risk factor for global disease burden and causes substantial health loss. We found that the risk of all-cause mortality, and of cancers specifically, rises with increasing levels of consumption, and the level of consumption that minimises health loss is zero. These results suggest that alcohol control policies might need to be revised worldwide, refocusing on efforts to lower overall population-level consumption.Peer reviewe