Scaling-up of the adsorption process of ammonia nitrogen onto expanded vermiculite using fixed-bed columns.

Expanded vermiculite was used as an adsorbent to remove ammonia nitrogen from landfill leachate. Bench and pilot-scale adsorption experiments were performed with leachate collected from a closed sanitary landfill located in Curitiba, southern Brazil. At the bench-scale, two different heights of vermiculite and three different flow rates were tested using a fixed-bed column. These tests produced an average uptake capacity of 33.4 mg g-1 for the ammonia nitrogen concentration of 2,560 mg L-1. The Yan model was used to determine the breakthrough and the exhaustion times due to the best fit of the data to this model. At the pilot-scale, the flow rate was determined from the shortest length of the mass transfer zone obtained from bench-scale experiments. Tests were performed using one stainless-steel column filled with 26.2 kg of expanded vermiculite, which resulted in a bed height of 1.6 m. A leachate flow rate of approximately 350 L d-1 was applied to achieve the required contact time of 8.3 h. At this scale, an average uptake capacity of 18.1 mg g-1 was obtained for the ammonia nitrogen concentration of 1,193 mg L-1. It is worth mentioning that the flow rate and the concentration of the adsorbate in the feeding solution are fundamental to improve the operational time of the fixed-bed column. The main goal of this research was the determination of operating conditions to scale-up the adsorption process of ammonia nitrogen onto expanded vermiculite. The contact time was a key parameter to reach this goal.

Response to correction of refractive errors and hypoaccommodation in children with congenital Zika syndrome.

PURPOSE: To describe the immediate response to correction of refractive errors and hypoaccommodation in children with congenital Zika syndrome (CZS). METHODS: Children born between May and December 2015 with a confirmed diagnosis of CZS and enrolled in a multidisciplinary early intervention program were included in this study. All children received a comprehensive ophthalmic examination, including dynamic retinoscopy and cycloplegic refraction. Children were prescribed their full correction if they met the criteria for refractive error, and additional plus 3.00 overcorrection for strabismus, accommodative dysfunction, and/or low vision. Monocular and binocular visual responses to Lea Grating Test at 30 cm, with and without eyeglasses, were measured on day 1 of glasses wear. RESULTS: A total of 60 children were evaluated (mean age at evaluation, 11.5 ± 1.1 months; range, 9.0-16.0 months). Lea Grating Test responses were abnormal in all children prior to spectacle correction. Hypoaccommodation was present in 17 of 21 children (81%). Overcorrection was prescribed for all children. Visual responses were subnormal even with glasses use; however, immediate improvement in binocular vision was found in 37 children (62%) and in 74 of 119 eyes (62.2%). For the monocular visual improvement, 27 of 115 eyes (23.5%) had structural abnormalities, and 44 of 115 eyes (38.3%) were structurally normal. There was a statistical difference between the cycloplegic refraction of the children in August and in November, including emmetropia (P = 0.001), hyperopia (P = 0.000), myopia (P = 0.007), and astigmatism (P = 0.004). CONCLUSIONS: Eyeglasses can improve visual acuity in children with CZS. Significant changes in their refractive status over time requires periodic updates.

Visual impairment in children with congenital Zika syndrome.

PURPOSE: To describe the visual impairment associated with ocular and neurological abnormalities in a cohort of children with congenital Zika syndrome (CZS). METHODS: This cross-sectional study included infants with microcephaly born in Pernambuco, Brazil, from May to December 2015. Immunoglobulin M antibody capture enzyme-linked immunosorbent assay for the Zika virus on the cerebrospinal fluid samples was positive for all infants. Clinical evaluation consisted of comprehensive ophthalmologic examination including visual acuity, visual function assessment, visual developmental milestone, neurologic examination, and neuroimaging. RESULTS: A total of 32 infants (18 males [56%]) were included. Mean age at examination was 5.7 ± 0.9 months (range, 4-7 months). Visual function and visual developmental milestone could not be tested in 1 child (3%). Visual impairment was detected in 32 infants (100%). Retinal and/or optic nerve findings were observed in 14 patients (44%). There was no statistical difference between the patients with ocular findings and those without (P = 0.180). All patients (100%) demonstrated neurological and neuroimaging abnormalities; 3 (9%) presented with late-onset of microcephaly. CONCLUSIONS: Children with CZS demonstrated visual impairment regardless of retina and/or optic nerve abnormalities. This finding suggests that cortical/cerebral visual impairment may be the most common cause of blindness identified in children with CZS.