The origin of high electrocatalytic activity of hydrogen peroxide reduction reaction by a g-C3N4/HOPG sensor.

Graphitic carbon nitride (g-C3N4) was synthesized from a low-cost precursor by means of a thermal process. The product was characterized by several spectroscopic techniques and the crystallinity was analyzed by X-ray diffraction. In the manufacture of the sensor, g-C3N4 was chemically exfoliated and a film was placed on the surface of a Highly Oriented Pyrolytic Graphite (HOPG). We compared the electrocatalytic activities of g-C3N4/HOPG and pristine HOPG surfaces as sensors for H2O2 quantification in buffer solution at pH 7. The results indicate that the surface of g-C3N4/HOPG exhibits striking analytical stability as well as reproducibility, enabling a reliable and sensitive determination within the 0.12-120 µM interval with a detection limit of 0.12 µM. These results suggest that this g-C3N4 film is a really particularly good nano-structured material to be applied as a biosensor. Chemical and physical factors are responsible for the outstanding electrocatalytic activity observed. The N in the g-C3N4 allows huge uptake of H2O2 through the hydrogen-bonding interaction and the change in the electronic structure since the HOPG/g-C3N4 heterojunction favors the charge transfer process through the interface.

Morphological Evolution of Noble Metal Nanoparticles in Chloroform: Mechanism of Switching on/off by Protic Species.

The morphological stability/morphological reshaping of noble metal nanoparticles are studied experimentally in order to unravel the chemical mechanisms lying beneath. Gold and silver nanoparticles (AuNPs and AgNPs, respectively) formed in chloroformic environment are used, as model synthetic systems, to study phenomena of morphological change. The morphological evolution of NPs that follows their formation, is characterized by spectroscopy (UV-Visible, Raman and FTIR) and TEM (Transmission Electron Microscopy). The change of NP morphology involves the increase of the average NP size and the broadening of size distribution, in a close resemblance with the effect characteristically obtained from the Ostwald ripening. The effect of the poor solvating properties of chloroform in stabilizing small charged species (H+, Ag+, Au+) as well as the principle of electroneutrality of matter are analyzed in order to formulate a feasible reaction scheme consisting of a three-step processes: the generation of soluble intermediary species by corrosion of nanoparticles, the diffusion of intermediary species from one nanoparticle to another, and the re-deposition process involving the reduction of intermediary species. This basic reaction scheme is used as hypothesis to plan and perform experiments, which reveal that molecular oxygen dissolved in the dispersive medium can drive NP corrosion, however, protic species are also required as co-reactant. The polarity of the hydrogen bond and the ligand properties of the anions produced by deprotonation are feature of the protic species that enable/disable the corrosion and, in turn, the NP morphological evolution.

Reversible stress softening of collagen based networks from the jumbo squid mantle (Dosidicus gigas).

Dosidicus gigas is the largest and one of the most abundant jumbo squids in the eastern Pacific Ocean. In this paper we have studied the muscle of the mantle of D. gigas (DGM). Morphological, thermal and rheological properties were assessed by means of atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential scanning calorimetry, thermogravimetry and oscillatory rheometry. This study allowed us to assess the morphological and rheological properties of a collagen based network occurring in nature. The results showed that the DGM network displays a nonlinear effect called reversible stress softening (RSS) that has been previously described for other types of biological structures such as naturally occurring cellulose networks and actin networks. We propose that the RSS could play a key role on the way jumbo squids withstand hydrostatic pressure. The results presented here confirm that this phenomenon occurs in a wider number of materials than previously thought, all of them exhibiting different size scales as well as physical conformation.

A novel mutation in limb girdle muscular dystrophy

We describe a patient with limb girdle muscular dystrophy with evidence of a D596N novel mutation of the LMNA gene. He presented with a dilated cardiomyopathy and heart failure. He successfully underwent a cardiac rehabilitation program without cardiovascular complications. Clinicians should suspect a variety of a wide array of diseases including laminopathy, dystrophinopathy, sarcoglynopathy and LGMD 2I. Further studies should focus on determining the specific mode of inheritance and genetic testing should be considered in these patients.

Influence of the polymeric morphology of sorbents on their properties in affinity chromatography.

The influence of the polymeric morphology of different types of Fe(3+)-containing sorbents and their properties in retention of phosphoamino acids is presented in this paper. Poly(hydroxylated polybutadienic-hydroxyethyl methacrylate) [poly(PB-HEMA)] and poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) [poly(EGDMA-HEMA)] base supports were submitted to chemical modifications to attain metal ion-containing sorbents. Properties such as specific surface area, pore volume, equilibrium volume swelling ratios, extent of conversion rate of functional groups, amount of chelated metal ion, ligand occupation, as well as quantity of phosphoamino acid retained, were used as comparative parameters for those different base matrices. Results suggest that Fe(3+) immobilized on poly(EGDMA-HEMA) base support are more efficient as a group-specific sorbent to retain phosphoamino acids than those obtained using poly(PB-HEMA) base support.

Prevalencia de displasia en casos de metaplasia gástrica. Estudio retrospectivo de 89 casos / Gastric dysplasia in gastric intestinal metaplasia

La tinción histológica de rutina: la hematoxilina eosina, continúa siendo la herramienta básica que evalúa los precursores de cáncer gástrico. Se le considera el estándar de oro vs. cualquier otro marcador debe compararse. En nuestro hospital recibimos anualmente 54 casos nuevos de cáncer gástrico, todos ellos en etapa avanzada al momento del diagnóstico y sólo con esperanza de paliación de la enfermedad. En un intento por reconocer marcadores preneoplásicos separamos los casos de metaplasia intestinal de cualquier índole en búsqueda de displasia. Entre 2160 biopsias gástricas de adultos recuperamos las preparaciones histológicas de 89 en quienes se hizo originalmente el diagnóstico de metaplasia. Se revisaron los casos por dos patólogos individualmente y se tabularon los diagnósticos. Encontramos 30 casos con evidencia de algún grado de displasia según los criterios de Morson. 14 correspondieron a displasia leve, 12 a moderada y cuatro a intensa. Los promedios de edad fueron de 59, 64 y 72 años respectivamente. En 21 casos el diagnóstico de ambos patólogos fue semejante. En los nueve restantes el diagnóstico difirió más de un grado, por lo que se decidió realizar la revisión simultánea de las preparaciones histológicas y el diagnóstico fue de común acuerdo. Concluimos que: 1) la aplicación simultánea de los criterios de Morson son evidentemente reproducibles y obligan al patólogo a asignar un grado de confianza, 2) Uno de cada tres casos de metaplasia en nuestro material cursa con displasia de algún grado, 3) De entre los casos de displasia más de la mitad (16/30) ameritarían seguimiento cuidadoso en búsqueda de neoplasia sincrónica o metacrónica

Validity of a standard information protocol provided to end-stage renal disease patients and its effect on treatment selection.

OBJECTIVE: To evaluate the validity of a standard information package, comprising written and audiovisual aids, for end-stage renal disease (ESRD) patients in a predialysis program. STUDY DESIGN: A multicenter study comprising patients entering a predialysis program. Three questionnaires were developed to gather data in this study: (1) a pre-information package questionnaire that evaluates the patient's initial knowledge of ESRD and the treatment options available (pre-informed patients); (2) a post-information package questionnaire that evaluates the patient's knowledge of ESRD and treatment options after being informed according to the protocol (post-informed patients); (3) a "start of the treatment" questionnaire that deals with the patient's choice of treatment at the time of starting dialysis, as well as the reasons leading to that choice. In all three questionnaires the patient's age, gender, level of creatinine clearance (Ccr), and hematocrit were recorded. INCLUSION CRITERIA: Any patient who was on a predialysis program in the participating centers. RESULTS: Three hundred and four patients were evaluated across 14 participating centers. Initial knowledge was assessed in 216 pre-informed patients (questionnaire 1). Patients were then guided through the information package. One hundred and fifty-eight patients answered the post-information package (questionnaire 2). During the course of the study, 174 patients (of the initial 304) started renal replacement therapy. Of these, 49.4% (86 patients) had received predialysis information according to our study protocol. All the patients who received the information throughout the trial improved their knowledge of ESRD and treatment options; this improvement was statistically significant. CONCLUSIONS: The treatment options least well known at the start of the study were the peritoneal dialysis techniques. After receiving the information package, patients had an equal knowledge of all the different treatments, although hemodialysis was still the most familiar. This improvement in knowledge enabled patients who started a dialysis treatment to choose a therapy according to their own preferences. Their selections were as follows: 44% of the patients chose hemodialysis, 40% chose continuous ambulatory peritoneal dialysis, and 16% chose automated peritoneal dialysis. The standard information package, used as a patient education program, effectively resulted in patients having a significantly improved level of knowledge and understanding of ESRD and the different treatment options available.

[A test to measure the degree of knowledge on food and nutrition at the onset of elementary school]. / Un test para medir el nivel de conocimientos alimentarios y nutricionales al inicio de la educación básica.

The objective of this work was to design a test to measure the degree of knowledge on food and nutrition in school-age children from elementary first and second grades. A graphic instrument was designed according to the psychological child development and was based on the specific objectives pursued by the curriculum programs of the Ministry of Education. The test was developed around the following topics through 15 items: Area 1: Basic Concepts on Food and Nutrition (9 items) and Area 2: Food, Personal and Environmental Hygiene (9 items). The test was pilot tested on 103 school-age children of both grades (1:1), of both sexes (1:1), belonging to Peñalolén and Las Condes counties from Chile's Metropolitan Region and from high and low socioeconomic status (SES) (1:1), measured through the Graffar's Modified Method. The final version of the test was applied in a representative sample of 1.482 school-age children from Chile's Metropolitan Region from elementary first and second grades during 1986-1987. Content validity was assured by a team of judges and by the curriculum programs. Reliability was assessed by the Spearman correlation with the Spearman-Brown correction. Item-test consistency was determined by the Pearson correlation coefficient. Data were processed by the statistical analysis system (SAS) package. Results showed that reliability coefficient was 0.84 and item-test consistency was equal or above 0.25 in all items. It can be concluded that this test can be useful to determine the degree of knowledge on food and nutrition at the onset of elementary school, both in Chile and in other countries.