Sustained release of calcium hydroxide from poly(dl-lactide-co-glycolide) acid microspheres for apexification

Calcium hydroxide (CH) loaded poly(dl-lactide-co-glycolide) acid (PLGA) microspheres (MS) might be used for apexification requiring a sustained release of Ca2+. The aim of this study was to formulate and characterize CH-PLGA-MS. The CH-loaded MS were prepared by either oil-in-water (O/W) or water-in-oil/in-water (W/O/W) emulsion solvent evaporation technique. MS produced by the O/W technique exhibited a larger diameter (18.63 ± 7.23 μm) than the MS produced by the W/O/W technique (15.25 ± 7.37 μm) (Mann–Whitney U test P &lt; 0.001). The CH encapsulation efficiency (Ee) and Ca2+ release were calculated from data obtained by absorption techniques. Ca2+ release profile was evaluated for 30 days. To know the Ee, the CH-loaded MS were dissolved in 1 M NaOH to release all its content and a Ca2+ colorimetric marker was added to this solution. The reagent marked the Ca2+ in blue color, which was then measured by a UV–Vis system (650 nm). The percentage of Ee was calculated on the basis of the theoretical loading. The Ee of the O/W-produced MS was higher (24 %) than the corresponding percentage of the W/O/W-produced MS (11 %). O/W- and W/O/W-produced MS released slower and lower Ca2+ than a control CH paste with polyethylene glycol 400 (Kruskal–Wallis test). O/W-produced MS released higher Ca2+ than W/O/W-produced MS (statistically significant differences; P < 0.05). In conclusion, the CH-PLGA-MS were successfully formulated; the technique of formulation influenced the size, encapsulation efficiency and release profile. The MS were better sustained release system than the CH paste

Can local policy options reverse the decline process of small and marginalized rural areas influenced by global change?

Rural depopulation generates deep territorial imbalances, threats regional food security, and causes the irreversible loss of culture and local institutions that manage natural resources and ecosystem services worldwide. While local leadership and economic diversification have been pointed as factors that could trigger rural development, what happens to remote rural areas whose continuous process of depopulation has undermined their social capital and leadership and their endogenous capacity for economic diversification? What realistic policy options could trigger an effective and endogenous rural development process in these weakened areas? Here we used a dynamic simulation model and a sensitivity analysis to explore the long-term effects of local policy options suggested by institutional, academic and local stakeholders that could act on leverage points to revert the depopulation of a marginalized rural area in Mexico, the oasis of Comondú in Baja California Sur. The identified leverage points are related to improving the production yields of irrigated agriculture and livestock farming, the main economic activities of this social-ecological system. Our results showed the positive, but limited, effects of acting on these leverage points. However, they seem plausible good places to act to start an endogenous revitalization process in this rural area. We found complementariness between the stakeholders’ management proposals, and high proximity of these proposals to the leverage points, especially the most place-based-specific proposals. This study shows the relevance of place-based research for rural development and how modeling is a valuable decision support tool to evaluate in advance the effectiveness of policy options proposed by stakeholders.Publishe

Diagnóstico de manejo de residuos sólidos urbanos en San Pedro Valencia y comunidades aledañas

El presente documento presenta los resultados de la investigación sobre la carencia de información y de prácticas socio-ambientales en San Pedro Valencia. La investigación consistió en hacer cuarteos de los residuos de la comunidad para obtener información más concreta sobre lo que se consume en las casas, en los restaurantes y en espacios públicos. Con esto, se planeó un mejor manejo de los residuos con el fin de disminuir la huella ambiental e incluso que puedan hacer negocio con ellos

Wireless multichannel optogenetic stimulators enabled by narrow bandwidth resonant tank circuits

Optogenetic neuromodulation is a powerful technique used to study cells that form part of neuronal circuits. Light stimulation of neurons has led to a deeper understanding of autism, schizophrenia and depression. However, researchers are often limited to tethered systems involving percutaneous plugs, hence, wireless power transmission to an implantable device is desirable. This work details the design, fabrication and testing of multichannel wirelessly powered optogenetic devices. By employing several carefully tuned resonant tank circuits, this work demonstrates the ability to address a scalable number of light sources on a single device. Single channel, dual channel and 16 channel devices were fabricated, achieving light output readings of up to 15mW at 473nm, suitable for activating channelrhodopsin. Wireless power transmission was characterized in air and porcine tissue for implant depths up to 30mm, making device implantation feasible. The device was successful in activating endogenous (in retinal ganglion cells) and exogenously transfected channelrhodopsin in human embryonic kidney cells, providing biological validation. The significance of this approach is the removal of power-hungry and area-consuming electronics from the implant, while the ability to address and modulate individual light sources is maintained by shifting this complexity to the external wireless power transmitter. © 2017 Elsevier B.V

Momento Económico (47)

En este número Momento político: La reforma electoral.. un fraude. El Banco Mundial y el endeudamiento apalancado. Consideraciones sobre la población y el desarrollo urbano-regional en el Plan Nacional de Desarrollo 1989-1994. México en la Cuenca del Pacífico, Arturo Ortiz Wadgymar América Latina: los caminos de la democratización y la ortodoxia. El camino hacia fuentes alternas de energía. El café mexicano y la crisis del mercado internacional. El nuevo Contrato Colectivo de Trabajo en Pemex. Temas de hoy

Production and Characterization of Biocomposite Films of Bacterial Cellulose from Kombucha and Coated with Chitosan

The purpose of this research is to produce and characterize bacterial cellulose (BC) films coated with chitosan (BC-CH). BC films were produced in a fermentation medium based on Camellia sinensis tea and dextrose (12 days at 25 °C) and subsequently treated with coating-forming solutions (CFSs) based on chitosan (BC-CH 0.5%, BC-CH 1.0%, and BC-CH 1.5%). As a result, the FTIR spectra of BC and BC-CH 1.5% showed the main characteristic bands of cellulose and chitosan. In the physicochemical characterization of the films, it was found that the incorporation of the chitosan coatings did not affect the thickness; however, it decreased the luminosity (L*) and increased redness (a*), yellowness (b*), and opacity (75.24%). Additionally, the light absorption properties in the UV-Vis range were improved. Furthermore, the application of the CFSs increased: the solubility (64.91%), the antimicrobial activity against S. aureus (6.55 mm) and E. coli (8.25 mm), as well as the antioxidant activity (57.71% and 24.57% free radical scavenging activity), and the content of total phenols (2.45 mg GAE/g). Finally, our results suggest that the BC-CH films developed in the present study show a potential application as active packaging material for food

Hybrid diamond/ carbon fiber microelectrodes enable multimodal electrical/chemical neural interfacing

Implantable medical devices are now in regular use to treat or ameliorate medical conditions, including movement disorders, chronic pain, cardiac arrhythmias, and hearing or vision loss. Aside from offering alternatives to pharmaceuticals, one major advantage of device therapy is the potential to monitor treatment efficacy, disease progression, and perhaps begin to uncover elusive mechanisms of diseases pathology. In an ideal system, neural stimulation, neural recording, and electrochemical sensing would be conducted by the same electrode in the same anatomical region. Carbon fiber (CF) microelectrodes are the appropriate size to achieve this goal and have shown excellent performance, in vivo. Their electrochemical properties, however, are not suitable for neural stimulation and electrochemical sensing. Here, we present a method to deposit high surface area conducting diamond on CF microelectrodes. This unique hybrid microelectrode is capable of recording single-neuron action potentials, delivering effective electrical stimulation pulses, and exhibits excellent electrochemical dopamine detection. Such electrodes are needed for the next generation of miniaturized, closed-loop implants that can self-tune therapies by monitoring both electrophysiological and biochemical biomarkers