Overview of Electrospinned Chitosan Nanofiber Composites for Wound Dressings

Chitosan has a medical application because of its natural origin and properties of biodegradability, biocompatibility, nontoxicity, and antimicrobial capacity. Electrospinning produces non-woven nanofibers to wound dressing with high specific surface area and small pores. These properties are favorable for absorption of exudates and prevent the penetration of bacteria, thus promoting wound healing. For this reason, chitosan blends are used to produce nanofiber dressings, and the characterization of the structural, mechanical, and biological properties is very promising for further studies. Nowadays, the researchers are seeking for biomaterials that provide modern dressings with many qualities, which are designed to promote wound healing. In this chapter, the electrospinning parameters that affect the nanofiber properties based on chitosan to prepare wound dressings are highlighted

Analogs of the double-Reissner-Nordstrom solution in magnetostatics and dilaton gravity: mathematical description and some physical properties

In this paper we consider a magnetic analog of the double-Reissner-Nordstrom solution and construct the corresponding magnetic potential A_\varphi in the explicit form. The behavior of the resulting solution under the Harrison transformation then naturally singles out the asymmetric black diholes - configurations composed of two non-extreme black holes possessing unequal masses, and charges equal in magnitude but opposite in sign - as its most general subclass for which equilibrium of the black-hole constituents can be achieved with the aid of the external magnetic (or electric) field. We also generalize the double-Reissner-Nordstrom solution to the dilaton gravity with arbitrary dilaton coupling, yielding as the result the 4-dimensional double-Gibbons-Maeda spacetime. The study of some physical properties of the solutions obtained leads, in particular, to very simple formulas for the areas of the horizons and surface gravities.Comment: 18 pages, 1 figure; title changed, typos corrected; a considerably extended version which includes the discussion of the magnetostatic case and the explicit formula for the magnetic potentia

Management of acute diverticulitis with pericolic free gas (ADIFAS). an international multicenter observational study

Background: There are no specific recommendations regarding the optimal management of this group of patients. The World Society of Emergency Surgery suggested a nonoperative strategy with antibiotic therapy, but this was a weak recommendation. This study aims to identify the optimal management of patients with acute diverticulitis (AD) presenting with pericolic free air with or without pericolic fluid. Methods: A multicenter, prospective, international study of patients diagnosed with AD and pericolic-free air with or without pericolic free fluid at a computed tomography (CT) scan between May 2020 and June 2021 was included. Patients were excluded if they had intra-abdominal distant free air, an abscess, generalized peritonitis, or less than a 1-year follow-up. The primary outcome was the rate of failure of nonoperative management within the index admission. Secondary outcomes included the rate of failure of nonoperative management within the first year and risk factors for failure. Results: A total of 810 patients were recruited across 69 European and South American centers; 744 patients (92%) were treated nonoperatively, and 66 (8%) underwent immediate surgery. Baseline characteristics were similar between groups. Hinchey II-IV on diagnostic imaging was the only independent risk factor for surgical intervention during index admission (odds ratios: 12.5, 95% CI: 2.4-64, P =0.003). Among patients treated nonoperatively, at index admission, 697 (94%) patients were discharged without any complications, 35 (4.7%) required emergency surgery, and 12 (1.6%) percutaneous drainage. Free pericolic fluid on CT scan was associated with a higher risk of failure of nonoperative management (odds ratios: 4.9, 95% CI: 1.2-19.9, P =0.023), with 88% of success compared to 96% without free fluid ( P <0.001). The rate of treatment failure with nonoperative management during the first year of follow-up was 16.5%. Conclusion: Patients with AD presenting with pericolic free gas can be successfully managed nonoperatively in the vast majority of cases. Patients with both free pericolic gas and free pericolic fluid on a CT scan are at a higher risk of failing nonoperative management and require closer observation

Morfololgía y desarrollo de la vivienda

El objetivo del proyecto fue generar un estudio sobre la vivienda y el área de restaurantes del poblado de San Pedro Valencia. Se llevó a cabo un análisis con la metodología de levantamiento y se crearon largueros con imágenes tomadas a lo largo de la mayoría de las cuadras de las viviendas existentes en la comunidad. Esto se realizó para poder determinar el lenguaje de la zona y así armar los elementos para descifrar y generar la propuestas ideal

Functional and antibacterial characterization of electrospun nanofiber membranes made of chitosan and polyvinyl alcohol

The development of nanomaterials with improved functional characteristics is a priority because of their applicability in medicine. Therefore, in this study, chitosan nanofiber membranes were electrospun with polyvinyl alcohol supplemented with carboxymethyl cellulose and pectin. The membrane characterization included identifying the functional groups of each polymer, the surface appearance, and the absorption capacity of aqueous media, simulating the exudates of skin diseases. Membrane weight loss was close to 50 % during the first day, and they preserved their integrity throughout the study. The mechanical characteristics demonstrated that the membranes with adjuvants are flexible and tough. The rigidity of the membranes was between 10.49 MPa and 22.65 MPa, and this rigidity decreased with the addition of chitosan and pectin. With chitosan, the elongation at break (8.25 %) was higher but the elastic modulus (450.78 MPa) was lower than those recorded with the other polymers. The effect against Staphylococcus aureus occurs due to chitosan and only by contact. In particular, an inhibition zone increased with the addition of chitosan (178.21 mm2). However, carboxymethyl cellulose showed the least shrinkage (4.4 %). Therefore, it is possible to produce nanofibers to make chitosan and polyvinyl alcohol membranes with improved functional characteristics by the addition of adjuvant agents as an alternative to other skin healing materials

Quién nos hubiera dicho : Guadalajara, 22 de abril

Obra que analiza la movilización civil que se produjo en Guadalajara como consecuencia de la tragedia vivida por la ciudad con las explosiones del 22 de abril de 1992. Además de la crónica de la tragedia, los textos incluyen artículos respecto de la demora de las autoridades en dictaminar sobre los responsables del desastre. A la vez, se enfatiza el papel jugado por distintos sectores de la sociedad civil en las tareas inmediatamente posteriores a las explosiones, así como en la reconstrucción a más largo plazo