Estudio de tubos de transferencia de calor

Optimizar el modelado matemático de un sistema de tubos de transferencia de calor, para simular y verificar los resultados a obtener con diferentes materiales, fluidos y condiciones de temperatura, a fin de ser aplicados los mismos a la construcción futura de equipamientos de calefacción para invernáculos en la zona de influencia de la Unidad Académica donde se desarrolla el presente trabajo. - Primera parte -Tema: Modelización y Simulación.Asociación Argentina de Energía Sola

Estudio de tubos de transferencia de calor

Optimizar el modelado matemático de un sistema de tubos de transferencia de calor, para simular y verificar los resultados a obtener con diferentes materiales, fluidos y condiciones de temperatura, a fin de ser aplicados los mismos a la construcción futura de equipamientos de calefacción para invernáculos en la zona de influencia de la Unidad Académica donde se desarrolla el presente trabajo. - Primera parte -Tema: Modelización y Simulación.Asociación Argentina de Energía Sola

Estudio de tubos de transferencia de calor

Optimizar el modelado matemático de un sistema de tubos de transferencia de calor, para simular y verificar los resultados a obtener con diferentes materiales, fluidos y condiciones de temperatura, a fin de ser aplicados los mismos a la construcción futura de equipamientos de calefacción para invernáculos en la zona de influencia de la Unidad Académica donde se desarrolla el presente trabajo. - Primera parte -Tema: Modelización y Simulación.Asociación Argentina de Energía Sola

The TexiSense « Smart Sock » - a device for a daily prevention of pressure ulcers in the diabetic foot

International audienceGoals.– The term « diabetic foot » refers to a set of foot pathologies essentially stemming from the neuropathy and arteriopathy of the lower limb associated with diabetes mellitus. Chronic ischemia weakens the healing potential and favors the development of wounds on a more vulnerable foot. Friction or repeated micro-traumas can lead to an ulceration (which in turn can end up in an amputation) that will remain unnoticed because of the somato-sensory deficiency. The current prevention techniques largely relying on visual inspection of the foot and enhancement of the foot/insole interface are not fully satisfying as the prevalence of plantar ulcers remains very high.Patients and methods.– A device for the prevention of plantar ulcers–called “Smart Sock” is described. It consists of:– a sock made of a 100% textile pressure sensing fabric developed by the TexiSense company;– a microcontroller running a biomechanical model of the soft tissues of the foot of the diabetic person;– a vibrating watch (and eventually a smartphone) used to warn the bearer if a pressure pattern threatens the soft tissues integrity.Results.– Internal overpressures within the soft tissues, especially nearby bony prominences are likely to develop into deep foot ulcerations. The biomechanical model gives an estimation of their magnitude based on the external pressures measured by the sock/sensor. This modeling relies on a faithful representation of the morphology of the diabetic subject. The device sends a vibro-tactile alert in case of occasional overpressure or excessive stress dose accumulated during daytime activities.Discussion.– The continuous use of the device, compatible with daytime activities of the diabetic person, helps compensate for the lack of attention in the prevention of pressure ulcer formation. The TexiSense “Smart Sock” can be designed so that when worn, pressure sensors fall onto sensitive anatomical areas such as the dorsal side of the toes or the posterior side of the heel, which makes it also possible to monitor regions located outside the sole of the foot

Body numerical phantoms for estimating soft tissue pains or injuries when interacting with shoes, seats and mattresses

International audienc

Influence of the calcaneus shape on the risk of posterior heel ulcer using 3D patient-specific biomechanical modeling.

International audienceMost posterior heel ulcers are the consequence of inactivity and prolonged time lying down on the back. They appear when pressures applied on the heel create high internal strains and the soft tissues are compressed by the calcaneus. It is therefore important to monitor those strains to prevent heel pressure ulcers. Using a biomechanical lower leg model, we propose to estimate the influence of the patient-specific calcaneus shape on the strains within the foot and to determine if the risk of pressure ulceration is related to the variability of this shape. The biomechanical model is discretized using a 3D Finite Element mesh representing the soft tissues, separated into four domains implementing Neo Hookean materials with different elasticities: skin, fat, Achilles' tendon, and muscles. Bones are modelled as rigid bodies attached to the tissues. Simulations show that the shape of the calcaneus has an influence on the formation of pressure ulcers with a mean variation of the maximum strain over 6.0 percentage points over 18 distinct morphologies. Furthermore, the models confirm the influence of the cushion on which the leg is resting: a softer cushion leading to lower strains, it has less chances of creating a pressure ulcer. The methodology used for patient-specific strain estimation could be used for the prevention of heel ulcer when coupled with a pressure sensor

Pressure ulcer prevention in spinal cord injury subjects using the TexiSense pressure sensing textile

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Bactericidal activities of the cationic steroid CSA-13 and the cathelicidin peptide LL-37 against Helicobacter pylori in simulated gastric juice

BACKGROUND: The worldwide appearance of drug-resistant strains of H. pylori motivates a search for new agents with therapeutic potential against this family of bacteria that colonizes the stomach, and is associated with adenocarcinoma development. This study was designed to assess in vitro the anti-H. pylori potential of cathelicidin LL-37 peptide, which is naturally present in gastric juice, its optimized synthetic analog WLBU2, and the non-peptide antibacterial agent ceragenin CSA-13. RESULTS: In agreement with previous studies, increased expression of hCAP-18/LL-37 was observed in gastric mucosa obtained from H. pylori infected subjects. MBC (minimum bactericidal concentration) values determined in nutrient-containing media range from 100-800 μg/ml for LL-37, 17.8-142 μg/ml for WLBU2 and 0.275-8.9 μg/ml for ceragenin CSA-13. These data indicate substantial, but widely differing antibacterial activities against clinical isolates of H. pylori. After incubation in simulated gastric juice (low pH with presence of pepsin) CSA-13, but not LL-37 or WLBU2, retained antibacterial activity. Compared to LL-37 and WLBU2 peptides, CSA-13 activity was also more resistant to inhibition by isolated host gastric mucins. CONCLUSION: These data indicate that cholic acid-based antimicrobial agents such as CSA-13 resist proteolytic degradation and inhibition by mucin and have potential for treatment of H. pylori infections, including those caused by the clarithromycin and/or metronidazole-resistant strains

Plasma Gelsolin Depletion and Circulating Actin in Sepsis—A Pilot Study

Background: Depletion of the circulating actin-binding protein, plasma gelsolin (pGSN) has been described in septic patients and animals. We hypothesized that the extent of pGSN reduction correlates with outcomes of septic patients and that circulating actin is a manifestation of sepsis. Methodology/Principal Findings: We assayed pGSN in plasma samples from non-surgical septic patients identified from a pre-existing database which prospectively enrolled patients admitted to adult intensive care units at an academic hospital. We identified 21 non-surgical septic patients for the study. Actinemia was detected in 17 of the 21 patients, suggesting actin released into circulation from injured tissues is a manifestation of sepsis. Furthermore, we documented the depletion of pGSN in human clinical sepsis, and that the survivors had significantly higher pGSN levels than the non-survivors (163647 mg/L vs. 89648 mg/L, p = 0.01). pGSN levels were more strongly predictive of 28-day mortality than APACHE III scores. For every quartile reduction in pGSN, the odds of death increased 3.4-fold. Conclusion: We conclude that circulating actin and pGSN deficiency are associated with early sepsis. The degree of pGS

Activity and Interactions of Liposomal Antibiotics in Presence of Polyanions and Sputum of Patients with Cystic Fibrosis

BACKGROUND:To compare the effectiveness of liposomal tobramycin or polymyxin B against Pseudomonas aeruginosa in the Cystic Fibrosis (CF) sputum and its inhibition by common polyanionic components such as DNA, F-actin, lipopolysaccharides (LPS), and lipoteichoic acid (LTA). METHODOLOGY:Liposomal formulations were prepared from a mixture of 1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine (DMPC) or 1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine (DPPC) and Cholesterol (Chol), respectively. Stability of the formulations in different biological milieus and antibacterial activities compared to conventional forms in the presence of the aforementioned inhibitory factors or CF sputum were evaluated. RESULTS:The formulations were stable in all conditions tested with no significant differences compared to the controls. Inhibition of antibiotic formulations by DNA/F-actin and LPS/LTA was concentration dependent. DNA/F-actin (125 to 1000 mg/L) and LPS/LTA (1 to 1000 mg/L) inhibited conventional tobramycin bioactivity, whereas, liposome-entrapped tobramycin was inhibited at higher concentrations--DNA/F-actin (500 to 1000 mg/L) and LPS/LTA (100 to 1000 mg/L). Neither polymyxin B formulation was inactivated by DNA/F-actin, but LPS/LTA (1 to 1000 mg/L) inhibited the drug in conventional form completely and higher concentrations of the inhibitors (100 to 1000 mg/L) was required to inhibit the liposome-entrapped polymyxin B. Co-incubation with inhibitory factors (1000 mg/L) increased conventional (16-fold) and liposomal (4-fold) tobramycin minimum bactericidal concentrations (MBCs), while both polymyxin B formulations were inhibited 64-fold. CONCLUSIONS:Liposome-entrapment reduced antibiotic inhibition up to 100-fold and the CFU of endogenous P. aeruginosa in sputum by 4-fold compared to the conventional antibiotic, suggesting their potential applications in CF lung infections