Synthesis and characterization of novel polyhydrazides containing pendant amide-imide-pyridine moiety

Eight novel polyhydrazides (PH _a4?Ch3 ) were prepared from the reaction of two novel diacids, 5-(2-(6-methyl pyridine-2-yl)-1,3-dioxo isoindoline-6-carboxamido) isophthalic acid (3) and 5-(2-(4-methyl pyridine-2-yl)-1,3-dioxo isoindoline-6-carboxamido) isophthalic acid (4), with four dihydrazides by interfacial polycondensation. These polymers have moderate inherent viscosities (0.12?C0.17?dL/g) and are readily soluble in polar aprotic solvents. They start to decompose (T _10%) above 187?°C and display glass transition temperatures in the range of 130.3?C156.3?°C. All polymers could be thermally converted into the corresponding polyoxadiazole approximately in the region of 250?°C, as evidenced by the DSC thermograms. All of the above polymers were fully characterized by FT-IR and ¹HNMR spectroscopy, TGA, DSC, and inherent viscosity measurement.     

Crystallisation regime of w/o emulsion [e.g. multipurpose margarine] models during storage

Multipurpose margarine (MPM) or water-in-oil (w/o) emulsion systems were prepared using palm oil (PO)/palm stearin (PS) blends as continuous phases and stabilized by monoacylglycerol (90% monoester) as emulsifier. Experimental analyses of three out of six models of MPM showed that MPM1, MPM2 and MPM3 had low workability force and weaker network structure. As results the solid fat content (SFC) at 28 °C, consistency, storage modulus (G′) and softness were 25%, 15.5 × 10² kPa, 2.62 × 10² kPa and 30 mm ease of cone penetration, respectively. Furthermore, examination microscopy of the images concerning MPM1, MPM2 and MPM3 revealed the presence of symmetrical crystals after 60 days of storage, whereas the MPM4, MPM5 and MPM6 models exhibited asymmetrical crystals during same incubation time. These results indicated that the diminution of PS versus PO contents induced the retardation of phase transition from less stable beta-prime (β′) crystals to the more stable beta (β) crystals during storage.     

A Comparative Study of Various Methods of Gear Faults Diagnosis

Investigating gear damages using vibration signal is a subject of a high interest, because gears vibration signals are complex and difficult to understand. A failure diagnosis of gearbox based on Fourier analysis of the vibration produced by speed reducers has shown its limits in terms of spectral resolution. In the present paper, a comparative study of the performances of various different methods of fault diagnosis of helicopter gearbox gear is carried out. The results are highlighted on the basis of real data recorded during a helicopter flight and have showed that cepstral analysis is most effective technique in detecting gearbox gear faults.     

The Endothelial Glycocalyx and Neonatal Sepsis

Sepsis carries a substantial risk of morbidity and mortality in newborns, especially preterm-born neonates. Endothelial glycocalyx (eGC) is a carbohydrate-rich layer lining the vascular endothelium, with important vascular barrier function and cell adhesion properties, serving also as a mechano-sensor for blood flow. eGC shedding is recognized as a fundamental pathophysiological process generating microvascular dysfunction, which in turn contributes to multiple organ failure and death in sepsis. Although the disruption of eGC and its consequences have been investigated intensively in the adult population, its composition, development, and potential mechanisms of action are still poorly studied during the neonatal period, and more specifically, in neonatal sepsis. Further knowledge on this topic may provide a better understanding of the molecular mechanisms that guide the sepsis pathology during the neonatal period, and would increase the usefulness of endothelial glycocalyx dysfunction as a diagnostic and prognostic biomarker. We reviewed several components of the eGC that help to deeply understand the mechanisms involved in the eGC disruption during the neonatal period. In addition, we evaluated the potential of eGC components as biomarkers and future targets to develop therapeutic strategies for neonatal sepsis.     

Developmental and environmental factors that enhance binding of Bordetella pertussis to human epithelial cells in relation to sudden infant death syndrome (SIDS)

The pharmacokinetic properties of glucagon-like peptide-1(7-36)amide (GLP-1(7-37) were compared. Four beagle dogs received on 4 separate occasions s.c. bolus doses of 50 micrograms/kg, and 2 min i.v. infusions of 50 micrograms/kg of each peptide. The plasma immunoreactivity of GLP-1 (P-GLP-1-IR) was measured by a sandwich enzyme-linked immunosorbent assay (ELISA). After i.v. infusion, the plasma half-life in the first-phase was 2.1 +/- 0.1 and 2.4 +/- 0.3 min, in the final-phase 68 +/- 6 and 81 +/- 3 min, the total plasma clearance 25 +/- 3 and 22 +/- 4 ml/kg.min, the volume of distribution at steady state 0.16 +/- 0.02 and 0.84 +/- 0.24 l/kg, and the mean residence time 6.2 +/- 0.3 and 36 +/- 5 min for GLP-1(7-36)amide and GLP-1(7-37), respectively. After s.c. administration, the maximum plasma concentration was reached after 15 +/- 5 and 19 +/- 4 min and the absolute bioavailability was 48 +/- 7 and 49 +/- 13% for GLP-1(7-36)amide and GLP-1(7-37), respectively. P-GLP-1-IR, measured by a radioimmunoassay (RIA), was considerably higher than when measured by ELISA. This discrepancy was due to cross-reactivity with metabolites of the parent peptide. The plasma degradation was studied in vitro in dog plasma at 37 degrees C, and the half-lives were found to be 61 +/- 9 and 132 +/- 16 min for GLP-1(7-36)amide and GLP-1(7-37), respectively (n = 6). Bacitracin inhibited the degradation of both peptides.     

Study of the effect of fumed silica on rigid PVC properties

This study seeks to substitute fumed silica for chlorinated polyethylene (CPE) within a rigid PVC formulation intended for profile extrusion such as doors and window frames. The effect of fumed silica on both mechanical (tensile and impact) and thermal (Vicat point, HDT, and linear thermal expansion coefficient) properties were investigated. Five rigid PVC formulations were prepared, including a reference one (F₁), then F₁ with CPE, F₁ with untreated silica, F₁ with heat treated silica, and finally F₁ with dried silica and a coupling agent. The effect of CPE on mechanical properties was very modest. On the other hand, CPE showed its inefficiency, in that HDT and Vicat point were decreased. Heat treated silica showed the greatest improvement in both mechanical and thermal properties. Untreated silica showed a small effect on both properties. Finally, the incorporation of coupling agent gave considerable improvement in both mechanical and thermal properties.