Positive sliding mode control for blood glucose regulation

Biological systems involving positive variables as concentrations are some examples of so-called positive systems. This is the case of the glycemia–insulinemia system considered in this paper. To cope with these physical constraints, it is shown that a positive sliding mode control (SMC) can be designed for glycemia regulation. The largest positive invariant set (PIS) is obtained for the insulinemia subsystem in open and closed loop. The existence of a positive SMC for glycemia regulation is shown here for the first time. Necessary conditions to design the sliding surface and the discontinuity gain are derived to guarantee a positive SMC for the insulin dynamics. SMC is designed to be positive everywhere in the largest closed-loop PIS of plasma insulin system. Two-stage SMC is employed; the last stage SMC2 block uses the glycemia error to design the desired insulin trajectory. Then the plasma insulin state is forced to track the reference via SMC1. The resulting desired insulin trajectory is the required virtual control input of the glycemia system to eliminate blood glucose (BG) error. The positive control is tested in silico on type-1 diabetic patients model derived from real-life clinical data.     

Evaluation of the determinants of flow-mediated radial artery vasodilatation in humans

The relative importance of the early peak response during hyperaemia and of the duration of the hyperaemic phase (t1/2: blood flow velocity half time and AUCt1/2: area under the curve of flow velocity at t1/2) in the magnitude of the flow-dependent vasodilatation of the radial artery was determined in humans. Radial artery diameter was measured continuously in 18 healthy volunteers using an echo-tracking system coupled to a Doppler device for the measurement of the radial blood flow. In 9 subjects, arterial parameters were measured at baseline and during 3 hyperaemic tests performed after 2, 5 or 10 minutes of ischaemia. Reproducibility of the measured parameters was studied in 9 other subjects. Radial artery diameter, AUCt1/2 and t1/2 increased proportionally with the duration of ischaemia. In contrast, the peak flow response was already maximal after 5 minutes of ischaemia. The regression analysis showed that the best fit model after stepwise analysis only included t1/2 (r = 0.85, p < 0.001). There was no correlation between the peak flow values and the duration of hyperaemia (r = 0.29, p = 0.14). These results demonstrate that conduit arteries postischaemic flow-dependent vasodilatation in humans is both determined by the peak value and by the duration of the hyperaemic phase and suggest that these two components must be considered when comparing this index of NO release between different groups of subjects.     

Temperature-insensitive polarimetric vibration sensor based on HiBi microstructured optical fiber

A new type of highly birefringent microstructured optical fiber has been tested for vibration measurements using a polarimetric technique. This technique takes advantage of the stress-induced phase shift between the two orthogonally polarized fiber eigenmodes. Comparison of three different fiber types shows that standard single-mode fibers do not provide stable measurements and that conventional polarization-maintaining fibers lead to a significant cross-sensitivity to temperature. However, for highly birefringent microstructured fibers specifically designed to provide a temperature-independent birefringence, our experiments show repeatable vibration measurements over a frequency range extending from 50?Hz to 1?kHz that are unaffected by temperature variations (up to 120?°C).     

Therapeutic Effects of Saponins for the Prevention and Treatment of Cancer by Ameliorating Inflammation and Angiogenesis and Inducing Antioxidant and Apoptotic Effects in Human Cells

Saponins are natural compounds found in plants and have a diverse range of applications. However, the therapeutic potential of saponins in regulating cytotoxicity, angiogenesis, and inflammation in mammalian cells is yet to be explored. Here, we investigated the therapeutic effects of saponins from green tea by exploring the cytotoxic effects of saponins by inducing apoptosis in the human cancer cell lines hepatocellular carcinoma (HEPG2) and colorectal adenocarcinoma (HT29). The anti-angiogenesis effect of saponins was also investigated in human umbilical vein endothelial cells (HUVEC). We explored the ability of saponins to attenuate inflammation in a dose-dependent manner in normal human cells. It was found that saponins exhibit cytotoxic effects in cancer cells and not in normal cells at the same concentration. Cytotoxicity was measured by inducing apoptosis by enhancing caspase-3 (cas-3) activation and B-cell lymphoma-2 (Bcl-2)-associated X protein (BAX) gene expression and suppressing the antiapoptotic protein, Bcl-2. The inhibition of HUVEC proliferation was due to the suppression of the phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), vascular endothelial growth factor receptor-2 (VEGFR-2), and nuclear factor kappa B (NF-κB). We also observed the antioxidant potential of green tea-derived saponins against free radicals in reactive oxygen species (ROS)-induced cells. Here we observed that the saponins exhibited free radical scavenging activities and activated nuclear factorerythroid 2-related factor 2 (NRF-2) leading to the upregulation of antioxidant-related genes in human embryonic kidney 293 (HEK293) cells. Furthermore, we demonstrated that the anti-inflammatory effects were due to the suppression of pro-inflammatory cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor-alpha (TNF-α), and inducible nitric oxide synthase (iNOS) in HEK293 cells. The significance of the work is we are the first to report on the anti-cancer effects of saponins based on the anti-inflammatory, antioxidant, anti-angiogenesis, and apoptosis induction properties. In conclusion, green tea-derived saponins could be effective therapeutics for the treatment of cancer.     

Partial sequencing of hog cholera virus Alfort strain genome and its comparison with other pestivirus strains

After molecular RNA cloning of the Alfort strain (Alfort/LCRV) of hog cholera virus (HCV), the nucleotide sequence of about 70% of the total genome was determined. This sequence was compared with homologous parts of previously published pestivirus genomes. The average homology with another clone of the Alfort strain (Alfort/FRC) was found to be lower (86.1%) than with Brescia strain of HCV (94.3%), while, compared with NADL, Osloss and SD-1 (3 different strains of bovine viral diarrhea virus, BVDV), the average homology was 67%. Although the amino-acid sequences show a higher degree of conservation, they had a similar degree of homology (92.7, 96.7, 69, 68.2 and 69%, respectively). Partial sequence comparison also revealed that Alfort/LCRV strain was more closely related to Alfort 187 (98.6% for the nucleotides and amino acids) and Weybridge (97.3% for the nucleotides and 96.1% for the amino acids) strains of HCV than it was to Alfort/FRC. These results may indicate that the Alfort/FRC strain has undergone more genomic variations during its historical passage. Genomic relationships among the pestiviruses are discussed.     

From Paper Drawings to Computer-Aided Design

A Canadian feasibility study shows that the key to reliable and cost-effective automatic reading of drawings is detailed planning of an operator-assisted system.     

Sucrose supplementation during traditional carob syrup processing affected its chemical characteristics and biological activities

The addition of sucrose is optional during carob syrups traditional processing. In this work, the polyphenolic profiles of carob syrups supplemented (CSS) or not with sugar (CS) were analyzed using RP-HPLC–ESI-MS. Quantitative data showed that adding of sucrose significantly (p < 0.05) decreased the polyphenolic amounts of about 58.6%, from 4.5 ± 0.32 to 1.86 ± 0.26 mg/g of CS and CSS, respectively. Gallic acid was the most abundant compound in both syrups representing 60.93% (CS) and 69.26% (CSS) of the total phenolics. Moreover, the adding of sugar decreased (p < 0.05) the antiradical potentials of 28% and 74%, as determined, respectively, by the ABTS and DPPH assays. CS was found to exhibit stronger antibacterial and antifungal activities than CSS. Bacillus cereus was the most sensitive strain to the extracts with CMI ≈500 (CS) and 622 (CSS) μg/ml. Both syrup extracts were cytotoxic to human neuroblastoma (SH-SY5Y) and fibroblast (3T3) cell lines as well as to mouse embryonic stem cells (D3). Tumoral SH-SY5Y cells were the most susceptible to the extracts with IC50 = 311.7 ± 23.65 (CS) and 390.6 ± 34.97 μg/ml (CSS). This study provides, for the first time, new analytical insights into traditionally made carob syrups and highlights the negative effect of sugar supplementation during processing.     

Thermal optimization of solar dish collector for indirect vapor generation

This work presented the performance analysis of a solar parabolic concentrator prototype. The purpose of this paper is to achieve most quantity of vapor production with different water flows. The principal component of the solar concentrator is a new absorber concept that absorbs reflected solar rays and transports it to a heat exchanger in order to generate vapor. Climatic conditions, inlet/outlet oil temperatures of the tubular solar heat exchanger, water tank temperature, and inlet/outlet water temperatures of the mixed heat exchanger were recorded experimentally during three days in November 2018. The absorbed energy, losses energy, concentrated energy, and vapor heat energy of the system were determined. Results of this work, the solar system provides thermal energy efficiency varied from 60% to 70% and a concentration factor around 350 for three water mass flow rates. In this experiment, the optimum value of vapor mass is 6 kg/h with 0.016 kg/s of water flow. Consequently, to achieve the most quantity of vapor, the water flow should be decreased.