A Theoretical Study of Arterial Disease by Transfer Function Analysis

A general method is proposed for a theoretical evaluation of the hemodynamic effects of stenosis on the arterial subsystem affected by it. In particular, it is applied to a lower limb stenosis, so as to compare the results of the theoretical analysis to those that other authors have obtained experimentally by processing Doppler ultrasound blood flow velocity measurements proximal and distal to a stenosis in the superficial femoral artery (SFA).     

A Simulation Study of Physiological Mechanisms Controlling Cerebral Blood Flow in Venous Hypertension

The paper presents a model for the cerebral circulation which emphasizes the interaction among the different control mechanisms in response to the perturbation produced by ligature of both jugular veins in the rat. The model's structure is determined on the basis of present knowledge of cerebrovascular control mechanisms and on the basis of hypotheses which find aposteriori confirmation in the fitting of the model to experimental responses. After stating the hypotheses and describing the general structure of the model, the corresponding equations are illustrated in detail and justified. The results obtained through numerical simulation mimic the great diversity of experimental responses and indicate the cause to be the range of gains characterizing the regulatory processes.     

Influence of water activity and molecular mobility on peroxidase activity in salt and sorbitol-maltodextrin systems

Solvent composition, system mobility and viscosity play a central role in the regulation of enzymatic activity.The aim of this study was to investigate the individual and combined effect of water activity (a_w), bulk viscosity and glass transition temperature () on the activity of horseradish peroxidase (HRP) in buffered solutions. For this purpose, the water activity of the solutions was modulated using both a ionic (sodium chloride) and a non-ionic (sorbitol) ligand and viscosity changed upon the addition of maltodextrin.In viscous solutions characterized by different compositions, the effectiveness of a solute in the inhibition of the HRP activity was dependent both on the chemical properties of the solution, as described by a_w, and on the mobility of the system, as described by the inverse of viscosity and T − . Viscosity was the most important factor in the inhibition of HRP activity in solutions characterized by the same value, but when was changed, due to changes in the solutes composition, the latter became a key factor in the regulation of the enzyme activity.In salt-maltodextrin systems the water activity reduction limited HRP activity with higher efficiency at low viscosities whilst in sorbitol-maltodextrin systems, characterised by different values, the a_w lowering by sorbitol addition resulted in the increase of HRP activity depending on its effect on .     

Effect of stepover and torch tilting angle on a repair process using WAAM

To sustain the transition to a greener economy and greener manufacturing, it is necessary to develop new approaches and technologies to repair metal components; this will result in a drastic reduction in energy and material usage. In this study, wire arc additive manufacturing (WAAM) was used to deposit a layer of new material on an existing surface, with the objective of finding the optimal configuration that maximized the layer quality and material efficiency. The parameters considered are the stepover among the deposited beads and the inclination of the torch with respect to the repaired surfaces. The inclination angle is crucial when repairing complex surfaces, like those of a mold, owing to accessibility issues, the torch cannot be maintained orthogonal to the surfaces along the entire toolpath. Different configurations were tested in order to assess the quality of the materials in terms of the presence of material voids, depth of penetration, and the heat affected zone (HAZ) and to understand the effects of these variables on the material efficiency and thickness of the repairing layer. It should be noted that by adopting deposition parameters set to have a low heat input, the use of a tilting angle has beneficial effects on the quality of the deposited layer and the process efficiency. Metallurgical and geometrical measurements were carried out to assess the effect of these two variables depositing a layer of plain carbon steel.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00393-2     

Engineered Ferritin Nanoparticles for the Bioluminescence Tracking of Nanodrug Delivery in Cancer

The identification of a highly sensitive method to check the delivery of administered nanodrugs into the tumor cells is a crucial step of preclinical studies aimed to develop new nanoformulated cures, since it allows the real therapeutic potential of these devices to be forecast. In the present work, the ability of an H‐ferritin (HFn) nanocage, already investigated as a powerful tool for cancer therapy thanks to its ability to actively interact with the transferrin receptor 1, to act as an efficient probe for the monitoring of nanodrug delivery to tumors is demonstrated. The final formulation is a bioluminescent nanoparticle, where the luciferin probe is conjugated on nanoparticle surface by means of a disulfide containing linker (Luc‐linker@HFn) which is subjected to glutathione‐induced cyclization in tumor cell cytoplasm. The prolonged imaging of luciferase+ tumor models, demonstrated by an in vitro and an in vivo approach, associated with the prolonged release of luciferin into cancer cells by disulfide bridge reduction, clearly indicates the high efficiency of Luc‐linker@HFn for drug delivery to the tumor tissues.     

n-alkane profiles of engine lubricating oil and particulate matter by molecular sieve extraction

As part of the Canadian Atmospheric Fine Particle Research Program to obtain reliable primary source emission profiles, a molecular sieve method was developed to reliably determine n-alkanes in lubricating oils, vehicle emissions, and mobile source dominated ambient particulate matter (PM). This work was also initiated to better calculate carbon preference index values (CPI: the ratio of the sums of odd over even n-alkanes), a parameter for estimating anthropogenic versus biogenic contributions in PM. n-Alkanes in lubricating oil and mobile source dominated PM are difficult to identify and quantify by gas chromatography due to the presence of similar components that cannot be fully resolved. This results in a hump, the unresolved complex mixture (UCM) that leads to incorrect n-alkane concentrations and CPI values. The sieve method yielded better chromatography, unambiguous identification of n-alkanes and allowed examination of differences between n-alkane profiles in light (LDV) and heavy duty vehicle (HDV) lubricating oils that would have been otherwise difficult. These profile differences made it possible to relate the LDV profile to that of the PM samples collected during a tunnel study in August 2001 near Vancouver (British Columbia, Canada). The n-alkane PM data revealed that longer sampling times result in a negative artifact, i.e., the desorption of the more volatile n-alkanes from the filters. Furthermore, the sieve procedure yielded n-alkane data that allowed calculation of accurate CPI values for lubricating oils and PM samples. Finally, this method may prove helpful in estimating the respective diesel and gasoline contributions to ambient PM.     

LTI models for 3-iodothyronamine time dynamics: a multiscale view

3-Iodothyronamine (T(1)AM) is a novel relative of thyroid hormone that plays a role in critical body regulatory processes such as glucose metabolism, thermal regulation, and heart beating. This paper was aimed at characterizing time dynamics of T(1)AM and its catabolite 3-iodothyroacetic acid (TA(1)) in different biological scales with linear time-invariant models. Culture medium samples coming from culture of H9c2 murine cells and perfusion liquid samples from perfused rat heart were collected after the injection of a T(1)AM bolus. T(1)AM and TA(1) concentrations in the samples were assayed with high-performance liquid chromatography coupled to tandem mass spectrometry. Kinetic constants relative to T(1)AM transport and conversion were estimated with weighted least-squares method. We found that these constants can be related with an allometric power law depending on mass, with a negative exponent of -0.27 ± 0.19, implying that the velocity of conversion and internalization of T(1)AM decreases with increasing of system mass.     

Effects of densitometry,material mapping and load estimation uncertainties on the accuracy of patient-specific finite-element models of the scapula

Patient-specific biomechanical models including patient-specific finite-element (FE) models are considered potentially important tools for providing personalized healthcare to patients with musculoskeletal diseases. A multi-step procedure is often needed to generate a patient-specific FE model. As all involved steps are associated with certain levels of uncertainty, it is important to study how the uncertainties of individual components propagate to final simulation results. In this study, we considered a specific case of this problem where the uncertainties of the involved steps were known and the aim was to determine the uncertainty of the predicted strain distribution. The effects of uncertainties of three important components of patient-specific models, including bone density, musculoskeletal loads and the parameters of the material mapping relationship on the predicted strain distributions, were studied. It was found that the number of uncertain components and the level of their uncertainty determine the uncertainty of simulation results. The ‘average’ uncertainty values were found to be relatively small even for high levels of uncertainty in the components of the model. The ‘maximum’ uncertainty values were, however, quite high and occurred in the areas of the scapula that are of the greatest clinical relevance. In addition, the uncertainty of the simulation result was found to be dependent on the type of movement analysed, with abduction movements presenting consistently lower uncertainty values than flexion movements.     

Rapid Quantification of Soyasaponins I and βg in Italian Lentils by High-Performance Liquid Chromatography (HPLC)–Tandem Mass Spectrometry (MS/MS)

In this work, an innovative and fast analytical method for the quantification of soyasaponins I and βg in lentils has been developed. Samples were extracted using 70 % aqueous ethanol at room temperature and then injected into a high-performance liquid chromatography–tandem mass spectrometry system. The correlation coefficients of calibration curves of the analyzed compounds were ≥0.9997. The recoveries obtained by spiking the lentil samples with a standard mixture of soyasaponins I and βg at 50 and 100 mg l^?1 were in the range of 96–101 and 98–103 %, respectively. The validated method was applied to the analysis of 30 lentil samples from central Italy. Soyasaponins I and βg were present in these lentils in concentrations that ranged from 54 to 226 mg kg^?1 and from 436 to 1,272 mg kg^?1, respectively. Our data indicated that lentils cultivated in fields at intermediate altitudes (1,142–1,387 m) showed the highest levels of soyasaponins, a finding confirmed by principal component analysis.