Mixtures of tertiary amine functionalized azo-containing mesogens with acid-functionalized polymers

A tertiary amine functionalized 4-nitro-4′-alkoxy azobenzene mesogen with a 10 or 12 carbon spacer (azo-nN) was synthesized and complexed in equimolar proportions with poly(acrylic acid) (PA-H) and poly(sulfonic acid) (PSS-H), and investigated by thermogravimetric analysis, differential scanning calorimetry, polarizing optical microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The neat azo-nN is characterized by a partial bilayer S_A mesophase at higher temperatures, and a highly ordered phase, in which the molecules are stacked orthogonally in bilayers, at lower temperatures. As supported by infrared analysis, for the azo-nN/PA-H mixture, the complexation is partial while for the same azo-nN/PSS-H mixture, complete proton transfer occurs. When the azo-nN is blended with the PA-H, regarded as a weak acid, a biphasic system is generated and the thermotropic behavior of neat mesogen is not significantly affected. In contrast, by mixing the same mesogen with a PSS-H (regarded as a strong acid), the thermotropic behavior is significantly influenced: the complexation generated a partial or interdigitated smectic A or tilted smectic C lamellar phase.     

Bio‐oil from whole‐tree feedstock in resol‐type phenolic resins

Renewable chemicals are of growing importance in terms of opportunities for environmental concerns over fossil‐based chemicals. Lignocellulosic biomass can be converted into energy and chemicals via thermal and biological processes. Among all the transformation processes available, fast pyrolysis is the only one to produce a high yield of a liquid‐phase product called bio‐oil or pyrolysis oil. Bio‐oil is considered to be a promising substitute for phenol in phenol formaldehyde (PF) resin synthesis. In this work, bio‐based phenolic resins have been formulated, partially substituting phenol by bio‐oils from two Canadian whole‐tree species. The new resins are produced by replacing 25, 50, and 75% of phenol with bio‐oil for each species (three bioresins per species). The aim of this study is to synthesize renewable resins with competitive price and satisfactory quality. The results obtained have shown that substitution degree up to 50% provided reactivity and performance equal or superior to the pure PF resin. They also present a good storage stability, improved shear strength, and thermal stability comparable to the pure PF. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40014.     

Testing degenerate polynomials

Two methods to test whether a given polynomial has two distinct roots whose quotient is a root of unity are discussed.     

Malaria in the southern sanitary district of Dakar (Senegal). 2. Entomologic data]

This study aimed to investigate the cause of persistently increased serum gastrin concentration seen in some Graves' disease patients even when euthyroid during antithyroid drug treatment. The subjects studied consisted of three groups: 33 patients with a common-type of Graves' disease, 14 with triiodothyronine (T3)-predominant Graves' disease (characterized from previous studies as having potent immunologic abnormalities including greater concentrations of thyroid-stimulating antibodies together with larger goiter size), and a group of 20 normal subjects. Fasting serum gastrin concentrations in common Graves' disease patients were significantly higher than those of normal subjects (58.4 +/- 38.9 pmol/L vs. 37.8 +/- 18.9 pmol/L [mean +/- SD], p < 0.05). The serum gastrin concentrations were even greater in T3-predominant Graves' disease patients than common Graves' disease patients (162.9 +/- 224.0 pmol/L vs. 58.4 +/- 38.9 pmol/L, p < .05). Serum pepsinogen I (PGI) concentrations were significantly lower in the T3-predominant patient group than the common Graves' group (24.0 +/- 12.9 ng/mL vs. 39.7 +/- 19.6 ng/mL, p < .05). Serum ratios of PG I to PG II were significantly lower in the T3-predominant Graves' disease patients than normal subjects (3.59 +/- 2.66 vs. 5.97 +/- 1.56, p < .01). The ratios also had a significant (p < .05) inverse correlation with serum gastrin concentrations in T3-predominant Graves' disease patients. The results suggest that autoimmune gastritis is associated with Graves' disease, particularly in patients with potent thyroid-autoimmunity.     

Pyramido-lunar fusion in black Africans. Apropos of 32 cases

Lunotriquetral coalition is a congenital carpal anomaly rarely discovered in a white population. In the black population, most cases have concerned blacks in America, Australia and South Africa. In the Sub-Saharia area, in Senegal, the authors, after 8 incidental cases, report 32 lunotriquetral coalitions collected in 20 patients. This retrospective study comparatively analysed 361 X-rays of the wrist performed between February 1989 and July 1992 in the Orthopaedic and Traumatologic Center (CTO) in Dakar. The bony coalition was bilateral in 12 patients and unilateral in the other 8 cases. The complete form (type III) was the most frequent (46.8%). In the bilateral forms, 5 patients presented this complete form. Lunotriquetral coalition was associated, in absence of congenital abnormalities, with a synovial cyst of the wrist (2 cases), scaphoid fracture (1 case), non-union of a scaphoid fracture (1 case) and osteoarthritis of the wrist (2 cases). After review of the literature, the authors discuss racial factors, anatomo-radiographic forms and associated injuries.     

The effect of lignin on the structure and characteristics of composite coatings electrodeposited on titanium

Composite coatings based on lignin, obtained by electrophoretic deposition (EPD) on titanium, were investigated. The aim of this work was to produce hydroxyapatite/lignin (HAP/Lig) coatings on titanium and to investigate the effect of the lignin concentration on microstructure, morphology, phase composition, thermal behavior and cytotoxicity of the HAP/Lig coatings. An organosolv lignin was used for the production of the composite coatings studied in this research. The properties of HAP/Lig coatings were characterized using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FT-IR) and X-ray photoelectron spectroscopy (XPS), as well as the MTT test of cytotoxicity. The results showed that higher lignin concentrations protected the HAP lattice during sintering, thereby improving the stability of the HAP/Lig coatings. The cell survival of peripheral blood mononuclear cells (PBMC) after proliferation indicates that the HAP/Lig coating with 1 wt% Lig electrodeposited on titanium was non-toxic with significant promise as a potential bone-repair material.     

Capital and operating costs of full-scale fecal sludge management and wastewater treatment systems in Dakar, Senegal

A financial comparison of a parallel sewer based (SB) system with activated sludge, and a fecal sludge management (FSM) system with onsite septic tanks, collection and transport (C&T) trucks, and drying beds was conducted. The annualized capital for the SB ($42.66 capita(-1) year(-1)) was ten times higher than the FSM ($4.05 capita(-1) year(-1)), the annual operating cost for the SB ($11.98 capita(-1) year(-1)) was 1.5 times higher than the FSM ($7.58 capita(-1) year(-1)), and the combined capital and operating for the SB ($54.64 capita(-1) year(-1)) was five times higher than FSM ($11.63 capita(-1) year(-1)). In Dakar, costs for SB are almost entirely borne by the sanitation utility, with only 6% of the annualized cost borne by users of the system. In addition to costing less overall, FSM operates with a different business model, with costs spread among households, private companies, and the utility. Hence, SB was 40 times more expensive to implement for the utility than FSM. However, the majority of FSM costs are borne at the household level and are inequitable. The results of the study illustrate that in low-income countries, vast improvements in sanitation can be affordable when employing FSM, whereas SB systems are prohibitively expensive.     

Congenital cardiopathies: anatomo-clinical, prognostic, and therapeutic features apropos of 103 cases seen at the Cardiology Clinic of the Dakar University Hospital Center

It has been demonstrated that short-term disinfection can affect the surface properties of impression materials. This study evaluated advancing contact angle, receding contact angle, inhibition and mass loss of a polyether impression materials, and two different viscosities of an addition silicone impression material after long-term immersion disinfection (18 hours). The brand names of the impression materials tested were Impregum F, Extrude Extra, and Extrude Wash, and all were tested by use of the Wilhelmy technique; first, for the nondisinfected state, which served as controls, and then after 1 and 18 hours of disinfection in a full-strength solution of acid glutaraldehyde. Weight changes before and after the disinfection process were also measured to detect weight loss and mass change over time. All materials exhibited some degree of inhibition. Polyether lost 0.4% mass in air, which indicated loss of a volatile component. Polyether and addition silicone were both relatively hydrophobic and could be disinfected with acid glutaraldehyde for up to 18 hours without affecting wettability.