Direct observation of endoglucanase fibrillation and rapid thickness identification of cellulose nanoplatelets using constructive interference.

Better understanding through direct observation of the mechanisms involved in chemical and enzymatic hydrolysis of biomass is of great importance, to implement a substitute for the common cellulose standards. We report the hydrolysis of biomass, using exclusively the parenchyma, to isolate cellulose nanoplatelets using a less harsh pretreatment. Then, we show direct evidence of the effect of endoglucanase on the structure of cellulose nanoplatelets, finding that amorphous cellulose is exclusively digested, loosening the cellulose nanofibrils in the process. The analysis of micrographs demonstrates that when cellulose nanoplatelets are deposited on a silicon wafer, its thickness can be qualitatively measured by the interference color detected using an optical microscope. This finding facilitates further studies of mechanisms involved in lignin removal and cellulose nanofibrils production by specific enzymatic digestion.

Eco-friendly isolation of cellulose nanoplatelets through oxidation under mild conditions.

Agave is recognized as a low recalcitrant material, which makes it a potential source to obtain nanocellulose. Aqueous dispersions (in water, H2O2, H2O2/H2SO4) of agave powder were heated at 120°C under vapor pressure (1kg/cm2). The resultant materials were observed with an optical microscope (OM), a laser scanning microscope (LSM) to obtain the thickness measurement and a scanning electron microscope (SEM) to observe morphology. Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to obtain the chemical structure. Cellulose nanoplatelets (CNPs) from Agave salmiana were successfully isolated under mild conditions. Physicochemical analysis indicates that lignin was removed in a single step oxidation with hydrogen peroxide in presence of sulfuric acid at low concentration (0.17M). The CNPs images revealed the presence of entangled cellulose nanofibrils (Ø≈14nm) along the nanoplatelets (thickness ≈80nm).

[Proposed normal values for alpha fetoprotein in maternal serum for the detection of neural tube closure defects and Down syndrome. Preliminary study]. / Propuesta de valores normales de alfa fetoproteína (AFP) en suero materno para la detección de defectos en el cierre del tubo neural (DCTN) y síndrome de Down (SD). Estudio preliminar.

To establish a normal range of alpha fetoprotein in maternal serum (AFP sm) in the population at the "20 de Noviembre" Hospital in Mexico City, there were studied 46 patients with a normal pregnancy confirmed with ultrasonography between 16 to 18 week of gestation. The 97 determinations of AFPsm were made by radioimmunoanalysis. The multiples of the median (MoM) were 2.16 al 16th weeks, 2.33 a 17th week 2.43 al 18th week of pregnancy. Now the methods to determine abnormalities in the product and the genetics studies are proposed only to the patients considered high risk (older than 35 years old, previous malformed son or family history of those abnormalities). AFPsm and the establishment of normal range allow us to amplify the study to every pregnant woman and to determine those malformations in the pregnant women of low risk which represents about 90-95% of DCTN and about 80% of SD.

[Morbidity and mortality in pregnant patients with lupus erythematosus]. / Morbimortalidad en la paciente lúpica embarazada.

The clinical records of 14 patients with proved diagnosis of sistemic lupus erythematosus (SLE) associated to pregnancy, seen between november 1986, and july 1988 at the "20 de Novembre" Hospital in Mexico City, were studied. The following variables were evaluated: maternal age, of beginning of SLE, lupus criteria present at the moment of the acute phase of the disease, obstetric history, prenatal care, age of pregnancy, laboratory studies, therapy before, during and after delivery, children's findings, and maternal complications, 50% of the patients had history of previous abortions; there was a high incidence of preterm deliveries (42.86%); 71.42% of the patients suffered hypertension; 64.31% had anemia. Therapy was based on corticosteroids and antihypertensive drugs. There was a significant relationship between low hemolitic complement levels and product's weight.