The aim of this contribution is to provide a comprehensive comparison between chitosan and Moringa oleifera seed flour (MOSF) as coagulant-flocculants. MOSF was obtained as a byproduct in a biodiesel process. Turbidity and heavy metal ion removal, using both ecofriendly materials, was assessed. Jar tests were performed on samples taken from river water, agricultural wastewater, and mixed wastewater (contaminated with agricultural and urban residues). Bioflocculant dosages within the range of 0.005-20 mg L À1 were tested. Irrespective of the initial turbidity, the optimal dosage of chitosan and MOSF for decreasing turbidity in river water was 1 and 5 mg L À1 , respectively. Furthermore, from river water, Pb removal up to 95% was achieved irrespective of the bioflocculant; for Mn removal, MOSF performed better than chitosan, with the adsorbent trapping close to 90% of this metal. MOSF decreased turbidity levels and heavy metal content (Mn and Pb) to under the permissible limits (Mexican environmental regulation for potable water, NOM-127-SSA1-1994). Additionally, kinetic data were fitted to kinetic models of adsorption for the pollutants. For agricultural wastewater, a chitosan dosage of 10 mg L À1 reduced turbidity to 5-10 nephelometric turbidity units (NTU), and a MOSF dosage of 10 mg L À1 decreased the turbidity to values lower than 5 NTU. For the mixed wastewater, chitosan achieved a high turbidity removal, while MOSF was not suitable.

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In Mexico, use of river water for households, agriculture and industry has adversely affected aquatic environment through chemical and microbial contamination. The aim of this study was to determine pesticide residues levels in water of rivers from central Sinaloa State, Northwestern Mexico. In samples obtained from July 2008 to June 2009 pesticides residues detected were lindane, heptachlor, endosulfan, dicloro difenil tricloroetano (DDT), diazinon, chlorpyrifos, permethrin, methyl parathion, cyromazine, ethion, carbofenothion, lambda cyhalotrine, pyrimicarb, malathion and aldrin. None exceeded water quality ecological criteria or those established by US Environmental Protection Agency. Comparatively low concentrations and frequencies suggest that pesticide contamination derived from runoffs toward river from contaminated soil particles and not from use of pesticides in intensive agriculture of region.

The hymenolepiosis by Hymenolepis nana is a major public health problem in developing countries, and the commercial drugs against this parasitosis are not enough effective. The combination of antiparasitic and antioxidant agents has improved the treatment of some parasitoses. Thus, the development of new cestocidal and antioxidant agents to treat the hymenolepiosis cases is important. In the present study, four hydroxy-and four dihydroxy-chalcones were synthesized using the catalyst boron trifluoride diethyl etherate (BF 3 •OEt 2 ). The antioxidant activity and antiparasitic against H. nana of chalcones were tested, as well as the toxicity by the brine shrimp lethality bioassay and the method of Lorke. The antioxidant activity was measured by three radical scavenging assays: 2,2'-azino-bis-3-ethylbenzothiazoline-6sulphonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP). The hydroxyl substitution pattern (number and position), mainly in ring B, was responsible for the chalcone antiparasitic activity. At least one meta or para hydroxyl group in ring B was essential for activity of the synthetic chalcones against H. nana; The time taken for the parasite to die by the 3b and 3e chalcones (20 mg/mL) treatment was up to six times lower than the control drug Praziquantel. On the other hand, chalcones with catechol structure in ring B (3g and 3h) showed the highest antioxidant values. The toxicity evaluations suggests that synthetic hydroxychalcones with cestocidal (3b and 3e) and antioxidant (3g and 3h) activities are safe compounds and potential in vivo agents to treat this parasitosis.

Regenerative therapy in dentistry has gained interest given the complexity to restore dental and periodontal tissues with inert materials. The best approach for regeneration requires three elements for restoring functions of affected or diseased organ tissues: cells, bioactive molecules, and scaffolds. This triad is capable of modulating the processes to replace lost or damaged tissues and restore function, as it has an impact on diverse cellular processes, influencing cell behavior positively to induce the complete restoration of function and morphology of such complex tissues. Hydrogels (HG) have shown advantages as scaffolds as they are soft and elastic three-dimensional (3D) networks formed from hydrophilic homopolymers, copolymers, or macromers. Besides simple or hybrid, HG show chemical, mechanical and biological activities such as the incorporation of cells in their structures, the retention of high-water content which enhances the transportation of cell nutrients and waste, and elastic and flexible characteristics that emulate the native extracellular matrix (ECM). HG can induce changes in cellular processes such as chemotaxis, proliferation, angiogenesis, biomineralization, and expression of specific tissue biomarkers, enhancing the regeneration process. Besides some of them have anti-inflammatory and anti-bacterial effects. This review aims to show an extensive overview of the most used hydrogels in tissue engineering, emphasizing those that are studied for the regeneration of oral tissues, their biological effects, and their clinical implications. Even though most of the HG are still under investigation, some of them have been studied in vitro and in vivo with outstanding results that may lead to preclinical studies. Besides there are HG that have shown their efficacy in patients such as hyaluronan HG that enhances the healing of gingival tissue.

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