Precise segmentation of the bulbar conjunctiva for hyperaemia images

Hyperaemia is an excess of blood in a tissue that causes the appearance of an unusual red hue in the affected area. It is a common occurrence in the bulbar conjunctiva, where it can be related to multiple pathologies, such as conjunctivitis or dry eye syndrome. Specialists grade hyperaemia by means of a tedious, subjective, non-repeatable and time-consuming process. These drawbacks can be solved with the automatisation of the process by means of image processing techniques. The automatic segmentation of the conjunctiva is an important part of the process, as it ensures the absence of noise in posterior stages of the methodology. However, there are several issues of illumination and focus in the input videos that difficult the process. In this work, several segmentation algorithms are proposed and compared in order to obtain an accurate location of the bulbar conjunctiva.     

Speckle size of light scattered from slightly rough cylindrical surfaces

This research is an extension of the optical method of quality control presented in a previous paper [Appl. Opt. 39, 5811 (2000)] to the case of slightly rough cylindrical surfaces. Applying the Kirchhoff scalar diffraction theory yields an analytical expression of the autocorrelation function of the intensity scattered from slightly rough cylindrical surfaces. This function, which is related to speckle size and shape, is shown to depend on the surface correlation length, unlike for plane surfaces for which the speckle depends on the illuminated area only. The theoretical expression is compared with that for the speckle produced by the light scattered from a cylindrical bearing and from various high-quality wires, showing that the method allows the correlation lengths of high-quality cylindrical surfaces to be determined.     

The flow of non-Newtonian slurries through fixed and fluidised beds

Measurements have been taken of the flow rate, pressure drop and bed height characteristics when non-Newtonian slurries flow through fixed and fluidised beds of uniformly sized spherical particles.In the case of fixed beds, the pressure drop-flow rate data has been interpreted using the capillary model of a porous medium together with rheological data for the slurries obtained from a tubular viscometer. The resulting friction factor-Reynolds number relationship is

This correlation was used to satisfactorily predict the minimum fluidisation velocity for a given solid/liquid system by equating the pressure drop to the net weight per unit area of particles in the bed. However, the correlation was not adequate for the prediction of bed expansion in the fluidised state. For systems which have a Reynolds number at minimum fluidisation, Re′_mf′ less than 40 an effect of particle diameter to bed diameter was observed. For systems having Re′_mf >40 the velocity, υ, and voidage, ?, were related to their values at minimum fluidisation by

It is therefore clear that, in the fluidised state, the capillary model does not present an adequate basis for the prediction of bed expansion.     

Changes in the permeability to gas of calcareous stone core samples exposed to salt spray

This paper describes a method of measuring the permeability of stone samples to nitrogen, applicable for studying the internal micro-structural transformations that occur in building stones when exposed to salt spray. In this method the gas enters through a previously drilled hole along the axis of a cylindrical stone sample and crosses the lateral surface by radial flux. For artificial weathering tests that affect the sample surface, this method is more suitable than the Cembureau method and gives similar permeability values. Furthermore, by changing the diameter of the hole drilled, it is possible to analyse the variations of the transfer property from the interior to the exposed surface and to study the localised effects of marine salts. The method was used during salt spray accelerated deterioration tests to asses the degree of saturation of the pores in calcareous stones traditionally used in construction in France.

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Résumé Nous décrivons dans cet article une méthode de mesure de perméabilité à l'azote mise au point pour étudier les modifications micro-structurales internes qui se manifestent dans des pierres de construction sous l'effet d'une exposition au brouillard salin. Le gaz est introduit par un trou préalablement usiné dans l'axe d'un échantillon cylindrique de pierre et traverse la surface latérale suivant un flux radial. Pour des tests de vieillissement affectant les surfaces, cet essai est plus adapté que la méthode Cembureau et fournit une mesure de la perméabilité tout à fait comparable. De plus, en jouant sur le diamètre de la perforation, on peut analyser l'évolution de la perméabilité du matériau en profondeur et au voisinage de la surface exposée et étudier les effets localisés des sels marins. La méthode de mesure a été utilisée au cours de simulations accélérées d'altération par brouillard salin, afin d'évaleur le degré de saturation de pores dans le cas de pierres calcaires traditionnellement utilisées dans la construction en France.

     

Insights into the Pharmacokinetics and In Vitro Cell-Based Studies of the Imidazoline I2 Receptor Ligand B06

The impact of neurodegenerative diseases (ND) is becoming unbearable for humankind due to their vast prevalence and the lack of efficacious treatments. In this scenario, we focused on imidazoline I₂ receptors (I₂-IR) that are widely distributed in the brain and are altered in patients with brain disorders. We took the challenge of modulating I₂-IR by developing structurally new molecules, in particular, a family of bicyclic α-iminophosphonates, endowed with high affinity and selectivity to these receptors. Treatment of two murine models, one for age-related cognitive decline and the other for Alzheimer’s disease (AD), with representative compound B06 ameliorated their cognitive impairment and improved their behavioural condition. Furthermore, B06 revealed beneficial in vitro ADME-Tox properties. The pharmacokinetics (PK) and metabolic profile are reported to de-risk B06 for progressing in the preclinical development. To further characterize the pharmacological properties of B06, we assessed its neuroprotective properties and beneficial effect in an in vitro model of Parkinson’s disease (PD). B06 rescued the human dopaminergic cell line SH-SY5Y from death after treatment with 6-hydroxydopamine (6-OHDA) and showed a crucial anti-inflammatory effect in a cellular model of neuroinflammation. This research reveals B06 as a putative candidate for advancing in the difficult path of drug discovery and supports the modulation of I₂-IR as a fresh approach for the therapy of ND.     

Determination of diffusion coefficients with a pipe wall electrode

A flow cell electrode has been designed to measure diffusion coefficients in electrochemical solutions. Potassium ferri-ferrocyanide solutions containing different amounts of sodium carboxymethylcellulose were studied. The diffusion coefficient of ferricyanide ion and the rheological properties of these solutions were measured at various temperatures.     

Current Challenges in Nucleic Acid Synthesis

Our understanding of the role of nucleic acids in regulating the process of life is growing rapidly. As researchers delve deeper into the cellular activity of molecules such as microRNA, small interfering RNA, and long non-coding RNA, the oligonucleotide chemist is confronted with the challenge of synthesizing the tools needed to continue this work. Furthermore, new applications are being developed that require increasingly complicated oligonucleotide constructs. In this review, we explore the current challenges confronting oligonucleotide synthesis, describe the chemistry and the enzymology being developed in response to those challenges, and discuss future challenges as-yet unmet.     

Cognitive Deficit in Schizophrenia: From Etiology to Novel Treatments

Schizophrenia is a major mental illness characterized by positive and negative symptoms, and by cognitive deficit. Although cognitive impairment is disabling for patients, it has been largely neglected in the treatment of schizophrenia. There are several reasons for this lack of treatments for cognitive deficit, but the complexity of its etiology—in which neuroanatomic, biochemical and genetic factors concur—has contributed to the lack of effective treatments. In the last few years, there have been several attempts to develop novel drugs for the treatment of cognitive impairment in schizophrenia. Despite these efforts, little progress has been made. The latest findings point to the importance of developing personalized treatments for schizophrenia which enhance neuroplasticity, and of combining pharmacological treatments with non-pharmacological measures.     

Ultralow power voltage reference circuit for implantable devices in standard CMOS technology

An ultralow power CMOS voltage reference for body implantable devices is presented in this paper. The circuit core consists of only regular threshold voltage PMOS transistors, thus leading to a very reduced output voltage dispersion, defined as σ/μ, and extremely low power consumption. A mathematical model of the generated reference voltage was obtained by solving circuit equations, and its numerical solution has been validated by extensive electrical simulations using a commercial circuit simulator. The proposed solution incorporates a passive RC low-pass filter, to enhance power supply rejection (PSR) over a wide frequency range, and a speed-up section, to accelerate the switching-on of the circuit. The prototype was implemented in 0.18 μm standard CMOS technology and is able to operate with supply voltages ranging from 0.7 to 1.8 V providing a measured output voltage value of 584.2 mV at the target temperature of 36° C. The measured σ/μ dispersion of the reference voltage generated is 0.65% without the need of trimming. At the minimum supply of 0.7 V, the experimental power consumption is 64.5 pW, while the measured PSR is kept below –60 dB from DC up to the MHz frequency range.