Reduction and oxidation kinetics of NiWO4 as an oxygen carrier for hydrogen storage by a chemical looping process.

NiWO4 with a volumetric storage density (VSD) of 496 g L-1 was studied to evaluate its H2 storage potential as an oxygen carrier under a chemical looping (CL) process scheme. The material was synthesized by precipitation and calcined at 950 °C for 5 hours in air. Characterization consisted in XRD, BET surface area, SEM and EDS analysis. NiWO4 hydrogen storage reduction-oxidation evaluation was performed by TGA using 5% v H2/Ar and 2.2% v H2O/Ar at 800 °C. Global kinetics for the reduction step was studied from 730 to 870 °C using 2 to 5% v of H2/Ar. While oxidation kinetics was examined from 730 to 870 °C using 0.8 to 2.2% v H2O/Ar. A hydrogen storage multicycle stability test was performed by exposing NiWO4 to 17 consecutive redox cycles. XRD results of the synthesized material indicate NiWO4 as the only crystalline phase. Fully reduced material found only W and Ni species, while reoxidation led back to NiWO4. BET surface area of synthesized material was 4.25 m2 g-1. SEM results showed fresh NiWO4 composed of non-porous large particles (1-5 µm). After reduction, the material shown a porous coral-like morphology with particles between 50 to 100 nm. EDS analysis results confirmed the compositions of the reduced (Ni + W) and fully oxidized NiWO4 species, respectively. Oxygen carrier reaction conversions for both reduction and regeneration steps were 100%. Global kinetic studies indicate a first order reaction for the two reduction steps and during oxidation, with activation energies of 22.1, 48.4 and 53.4 kJ mol-1 for the two reduction and oxidation steps, respectively. NiWO4 multicycle stability test shown no loss of VSD and fast reduction and oxidation kinetics under the studied conditions after seventeen consecutive redox cycles, which confirms the potential of this material with respect to current oxygen carriers reported in the literature for hydrogen storage applications.

Rectum leiomyoma in a 10-month-old female.

An unexpected case of leiomyoma (LM) of the rectum in a 10-month-old female patient. The patient presented with a palpable mass and symptoms of intestinal obstruction, constipation and rectal discomfort. Rectal examination revealed a clearly visible mass. The treatment consisted of a surgical resection with wide margins. Pathology reported a leiomyoma. The patient was submitted to a careful clinical evaluation and a continuous follow up.

[Percutaneous endoscopic gastrotomy (GEP): designed reusable (NAGEP) for one time endoscopic technique. Experimental study in dogs]. / Gastrostomía endoscópica percutánea (GEP): dispositivo diseñado reutilizable (NAGEP) en técnica endoscópica de un tiempo. Estudio experimental en perros.

INTRODUCTION: This aim of our experimental study was to demonstrate the versatility of our designed reusable device for PEG and its future application in humans. MATERIALS AND METHODS: 20 mongrel dogs received enteral nutrition by a Foley tube placed by a single endoscopic technique using a reusable stainless steel designed device, three reusable stainless steel designed device, three reusable stainless steel dilators, an Olympus XQ20 video gastrointestinal endoscope, basic surgical equipment and surgical material. RESULTS: The procedure was successfully performed in all dogs under general anaesthesia. The duration of the whole procedure ranged from 10 to 18 min. The complications regardless by the PEG procedure were minimal. The Foley tube was retained by 15 days. CONCLUSIONS: The application of the stainless steel reusable designed device for the PEG is safe, and presents several advantages. This technique for PEG placement could be used in the future due the characteristics of the designed device: durable and reusable for unlimited number of procedures.

Gastrostomía endoscópica percutánea (GEP): dispositivo diseñado reutilizable (NAGEP) en técnica endoscópica de un tiempo. Estudio experimental en perros. / [Percutaneous endoscopic gastrotomy (GEP): designed reusable (NAGEP) for one time endoscopic technique. Experimental study in dogs]

INTRODUCTION: This aim of our experimental study was to demonstrate the versatility of our designed reusable device for PEG and its future application in humans. MATERIALS AND METHODS: 20 mongrel dogs received enteral nutrition by a Foley tube placed by a single endoscopic technique using a reusable stainless steel designed device, three reusable stainless steel designed device, three reusable stainless steel dilators, an Olympus XQ20 video gastrointestinal endoscope, basic surgical equipment and surgical material. RESULTS: The procedure was successfully performed in all dogs under general anaesthesia. The duration of the whole procedure ranged from 10 to 18 min. The complications regardless by the PEG procedure were minimal. The Foley tube was retained by 15 days. CONCLUSIONS: The application of the stainless steel reusable designed device for the PEG is safe, and presents several advantages. This technique for PEG placement could be used in the future due the characteristics of the designed device: durable and reusable for unlimited number of procedures.

[Prevalence of deficiency of thyroxine-binding globulin (TBG)]. / Prevalencia de la deficiencia de globulina ligada a la tiroxina (TBG).

During 3 years 1632 newborns from Gorgas Army hospital had their cord blood screened for congenital hypothyroidism by determining serum thyroxine levels (T4). Fifty-five had serum levels below 7 mcg/dl and 80% of them went into a confirmatory evaluation for hypothyroidism. Three of those (1.8/1000 live birth) had a familiar deficiency of thyroid binding globulin (TBG). All of them were male newborns born at 38 weeks of gestation. The average T4 from the umbilical cord was 2.4 +/- 1.3 mcg/dl. This value was significantly lower than the values from those with an initial T4 below 7 mcg/dl who did not have TBG deficiency. The prevalence of TBG deficiency in this study was about 10 times higher than the prevalence reported by other authors for both the general population and the male population.

[Intravenous gamma globulin in newborns]. / Gamaglobulina intravenosa en neonatos.

Eight newborns with a mean gestational age of 36.1 weeks and a mean weight of 2863 grams were treated intravenously with 3% gammaglobulin (Sandoglobulina). We used two different infusion rates: one, of 0.5-1.5 mg/kg/min., and a second one, of 7-9 mg/kg/min. Close cardiopulmonary monitoring was carried out by bioelectronic means. The changes of heart rate, mean blood pressure and respiratory rate before and during the gammaglobulin infusion were recorded. We did not find any significant variation between the values recorded before and during the infusion. These values were all within tolerable physiological ranges except for those for respiratory rate, where 7 out of 8 patients had mild tachypnea. Stable sick newborn because of bacterial infections tolerated well the infusion of intravenous gammaglobulin at rates of 0.5-9.0 mg/kg/min., when the doses used were between 0.25 mg/kg/day and 1.0 gm/kg/day, for 4-6 days.

[Bacteremia and neonatal sepsis]. / Bacteremia y sepsis neonatal.

A prospective evaluation of bacterial growth in blood of neonates at risk for early neonatal sepsis was carried on between January 1 st., 1989 and December 31, 1989. From all admissions to Gorgas Military Hospital Neonatal Unit in Ancon, Panama, 11.1% had perinatal risk factors for early sepsis. Fourteen percent (14.1%) had radiologic findings consisting with intrauterine pneumonia, and 1.6% had urinary tract infection. None of them grew any bacteria from blood cultures. Only 1 out of 64 newborns had a positive blood culture with the clinical picture of sepsis. This patient's blood culture grew Group B beta hemolytic Streptococcus. Confirmed sepsis incidence was 1.7/1000 live births while suspected sepsis incidence for this population and during this study period was 65 times higher.