Biogas and calcite handling in calcium fluoride precipitation from aqueous solution guided by thermodynamic simulation with PHREEQC.

In this innovative study, biogas has been associated with calcium carbonate [CaCO3] to promote the precipitation of fluorite, aiming at the treatment of wastewater with high content of fluoride. The work associates distinct sources of calcium and CO2 for the precipitation of fluorite according to previous simulation with the free software PHREEQC. Considering the reaction at equilibrium, the minimal predicted Ca dosage was 215 mg/L, lower than the 430 mg/L that was experimentally determined, independent of Ca source. The simultaneous use of CaCO3 and CO2 from distinct gas sources (pure CO2, 1:1 CO2:N2, and biogas) exhibited high performance permitting the reduction of fluoride content from 134 to 10 mg/L, with low gas consumption. The biogas consumption of 66.0 mmol/L, equivalent to 33.4 mmol/L of CO2 (1.47 kgCO2/m3treated wastewater) was predicted, indicating that the biogas storage bag of 700 L would be able to treat 469 L of wastewater. Furthermore, the inert fraction of biogas (CH4) did not impact the reaction and it may be used after the reaction as an alternative source of power, equivalent to 8.25 kWh/m3treated wastewater. Final solids were composed by fluorite and non-dissolved calcite, confirming the predictions obtained by PHREEQC.

Cow bones char as a green sorbent for fluorides removal from aqueous solutions: batch and fixed-bed studies.

Cow bone char was investigated as sorbent for the defluoridation of aqueous solutions. The cow bone char was characterized in terms of its morphology, chemical composition, and functional groups present on the bone char surface using different analytical techniques: SEM, EDS, N2-BET method, and FTIR. Batch equilibrium studies were performed for the bone chars prepared using different procedures. The highest sorption capacities for fluoride were obtained for the acid washed (q = 6.2 ± 0.5 mg/g) and Al-doped (q = 6.4 ± 0.3 mg/g) bone chars. Langmuir and Freundlich models fitted well the equilibrium sorption data. Fluoride removal rate in batch system is fast in the first 5 h, decreasing after this time until achieving equilibrium due to pore diffusion. The presence of carbonate and bicarbonate ions in the aqueous solution contributes to a decrease of the fluoride sorption capacity of the bone char by 79 and 31 %, respectively. Regeneration of the F-loaded bone char using 0.5 M NaOH solution leads to a sorption capacity for fluoride of 3.1 mg/g in the second loading cycle. Fluoride breakthrough curve obtained in a fixed-bed column presents an asymmetrical S-shaped form, with a slow approach of C/C 0 â†’ 1.0 due to pore diffusion phenomena. Considering the guideline value for drinking water of 1.5 mg F-/L, as recommended by World Health Organization, the service cycle for fluoride removal was of 71.0 h ([F-]feed âˆ¼ 9 mg/L; flow rate = 1 mL/min; m sorbent = 12.6 g). A mass transfer model considering the pore diffusion was able to satisfactorily describe the experimental data obtained in batch and continuous systems.

Patterns of sound change in children with phonological disorders.

This paper presents longitudinal data that provide insight into the phonological learning of five children. These children were superficially similar in that all presented with errors affecting production of [s]; however, it will be argued that each child possessed a phonological system that was unique in certain ways. Production of [s]was established with each participant using a motoric training approach, and generalization was assessed over a 3-4-month period using a 50-item probe. Once treatment was initiated, changes in the production of [s]and in other properties of the phonological systems were observed. Some of these changes illustrated apparent learning strategies that were child-specific, whereas other changes were common to all of these children and may, in fact, be universal in nature.

Facilitating [s] production in young children: an experimental evaluation of motoric and conceptual treatment approaches.

Eighteen phonologically disordered children were assigned to one of two experimental treatment programmes. Half of the children received a motoric treatment, which focused on establishing sound production in isolation, words, and phrases. The remaining children received a conceptual treatment, which sought to establish the phonemic nature of /s/ without providing motor practice. Treatment efficacy was evaluated by analysing [s] production during administration of a generalization probe. The motoric treatment was more effective overall; although some subjects, whose phonetic inventory included [s] prior to treatment, generalized correct production following the introduction of the conceptual treatment.

Enhancing stimulability: a treatment program.

Recent research on stimulability and generalization suggests that treatment of nonstimulable sounds results in maximum treatment gains (Powell, Elbert, & Dinnsen, 1991). It has also been suggested, however, that nonstimulable sounds are more difficult to teach, especially to young children with very small phonetic inventories. In this article, we describe a treatment program designed to increase the size of the phonetic inventory by "teaching" stimulability. Application of the treatment approach is demonstrated in a case study.

Spectral analysis of target-appropriate /t/ and /k/ produced by phonologically disordered and normally articulating children.

Previous research (Forrest, Weismer, Hodge, Dinnsen and Elbert, 1990) has shown that some phonologically disordered children differentially mark seemingly homophonous phonemes; however, the resulting contrast may be spectrally distinct from that produced by normally articulating children of the same age. In the present investigation possible sources for these differences between normally articulating and phonologically disordered children's productions of target-appropriate phonemes were pursued. Spectral characteristics of seemingly correct productions of /t/ and /k/ in word-initial position were analysed for four normally articulating and seven phonologically disordered children to assess the effect of recency of acquisition, depth of knowledge of the contrast and/or the effect of a phonological disorder on accuracy and variability of production. Results revealed that children who had acquired the velar-alveolar contrast more recently, and who had incomplete knowledge of that contrast, produced target-appropriate /t/ and /k/ differently from their normally articulating peers and other phonologically disordered children with greater knowledge of the contrast. Further, the phonologically disordered children with incomplete knowledge of the velar-alveolar contrast were less variable than the other phonologically disordered or normally articulating children in the spectral characteristics across repeated productions. Analysis of the spectral characteristics of word-initial /t/ and /k/ at a later point in time indicated similarities between all speaker groups in the spectral parameters that distinguished the velar from the alveolar stop. However, the stability of these parameters across repeated productions decreased for the phonologically disordered children with greater knowledge of the contrast. These effects are related to motor skill development and found to be consistent with previously demonstrated patterns of skill acquisition.

Stimulability as a factor in the phonological generalization of misarticulating preschool children.

The relationship among six functionally misarticulating preschool children's phoneme-specific stimulability skills, the choice of treatment targets (i.e., stimulable or nonstimulable sounds), and generalization of correct sound production was explored in this prospective study. Each subject [age range of 4:11 (years:months) to 5:6] was taught to produce [r] and one other sound that was absent from his or her phonetic inventory using a contrasting-minimal-pairs production approach. A multiple baseline across behaviors single-subject research design provided experimental control. For 86% of the 28 monitored sounds, generalization was consistent with pretreatment stimulability skills; production of stimulable sounds tended to improve regardless of treatment target. These results suggest that nonstimulable sounds are likely to require direct treatment; thus, generalization probe responses may be maximized by treating nonstimulable sounds rather than stimulable sounds.

Toward a technology of generalization: how many exemplars are sufficient?

This descriptive study examined the number of minimal-word-pair exemplars necessary for 19 phonologically impaired children to meet a generalization criterion. For 59% of the test cases, three exemplars were sufficient for generalization to occur. Five exemplars were sufficient in 21% of the test cases, and it was necessary to teach 10 different exemplars in 14% of the test cases. In 7% of the test cases, generalization did not occur despite treatment on 10 exemplars. Although generalization usually occurred following treatment using a small number of exemplars, there was substantial variability across individual subjects. There was no apparent relationship between specific sounds and the likelihood of generalization; however, the data from some children suggested that treatment on one sound enhances learning of subsequent sounds. The theoretical and clinical implications of these findings are discussed.

Generalization to conversational speech.

Although changes in children's phonological systems due to treatment have been documented in single-word testing, changes in conversational speech are less well known. Single-word and conversation samples were analyzed for 10 phonologically disordered children, before and after treatment and 3 months later. Results suggest that for most of the children, there were system changes in both single words and in conversational speech. It appears that many phonologically disordered children are able to extend their correct production to conversation without direct treatment on spontaneous speech.

Listeners' familiarity and perception of an idiosyncratic phonologic pattern.

Idiosyncratic production of [l] for target /j/ (for example, production of the word "less" for "yes") was observed in a phonologically impaired preschooler. Recordings of his apparently homonymous productions of minimal pairs contrasting /j/ and /l/ were presented in random order to the child's mother and to five adult listeners who were unfamiliar with the child. No difference was seen across the listeners in their ability to identify target /l/ words. The child's mother, however, correctly identified /j/ targets more frequently than did unfamiliar listeners suggesting that familiarity enhances one's ability to decode idiosyncratic phonologic error patterns.

Some constraints on functionally disordered phonologies: phonetic inventories and phonotactics.

The phonological systems of 40 functional misarticulators, ages 40 to 80 months were examined in terms of the nature and variation of phonetic inventories and phonotactic constraints. It was found that these properties of disordered systems were governed by severe constraints that yielded a typological characterization of such systems along with associated implicational laws. The principles governing disordered systems were also found to parallel closely the principles governing normal first language acquisition. The evidence suggests that at least these properties of disordered systems represent delays in the normal acquisition process and are not otherwise deviant. The assessment and treatment of functional disorders along with the projection of learning patterns can thus appeal to principles governing such phonological systems.

Evaluating the treatment effect of repeated probes.

This study investigated the effect of the administration of frequent and infrequent probe lists on generalization to novel stimuli. Four subjects with multiple functional articulation errors were taught to produce two different sounds, and generalization was measured on three probe lists. Two of the probe lists (one for each sound) were administered infrequently, and the third probe list (for one sound) was presented at each treatment session. The results indicated that the frequent rate of administration of probe lists did not produce any predictable effect on the extent of generalization or the occurrence of a practice effect. In general, the data continue to support the use of probe lists as an effective tool to measure generalization.

A functional analysis of phonological knowledge and generalization learning in misarticulating children.

It has been suggested that a child's productive phonological knowledge may be one factor that potentially accounts for individual differences in generalization learning observed among phonologically disordered children (Dinnsen & Elbert, 1984; Elbert, Dinnsen, & Powell, 1984). This paper evaluates the hypothesis that productive phonological knowledge influences generalization. Three related studies involving 6 functionally misarticulating children were conducted. In the first study, a description of each child's phonological system was developed using procedures of standard generative analysis. Based upon these descriptions, each child's productive phonological knowledge of his or her own sound system was determined and then ranked on a continuum ranging from "most" to "least" knowledge relative to the adult target. The second study implemented an experimental treatment program based upon each child's productive phonological knowledge, with treatment sounds selected directly from each child's continuum of knowledge. The third study reassessed each child's productive phonological knowledge following treatment. The results of these three studies indicated that a child's productive phonological knowledge of the sound system influenced the overall amount of generalization learning. However, the extent of generalization learning was associated with the point on the knowledge continuum at which treatment was initiated. These findings are discussed with reference to individual differences in generalization learning.

[Clinical aspects and observations on patients with lymphadenopathy syndrome]. / Klinik und Verlaufsbeobachtungen bei Patienten mit Lymphadenopathie-Syndrom.

Since November 1982, patients with symptoms suggesting a lymphadenopathy syndrome (LAS) or acquired immune deficiency syndrome (AIDS), as well as their contacts and persons in high risk groups were examined as out-patients. The examinations have now been concluded in 101 patients. The patients were divided into 3 groups according to clinical symptoms and the OKT4+/OKT8+ ratio: 30 patients with normal ratio (group I), 59 patients with LAS and a ratio of less than 1 (group II) and 12 patients with fully developed AIDS (group III). During a follow-up time of 18 months, 3 patients of group I developed LAS and 1 patient in group II developed toxoplasma encephalitis. In a further 2 patients with LAS, uncharacteristic symptoms such as fever, tiredness and loss of weight increased, while at the same time the number of OKT4+ cells and thus the ratio fell significantly. In 4 cases the immunological parameters and the clinical picture improved. In 52 patients the clinical picture and the laboratory findings did not change. The demonstration of retrovirus HTLV III would seem to provide the cause of LAS and AIDS. Nonetheless, follow-up observation of contacts and patients with LAS remain important.

Untrained acquisition of /s/ in a phonologically disordered child.

The untrained /s/ productions of a phonologically disordered child were followed over a period of several months as she produced /s/ in imitated words and in spontaneous connected speech. For this child, as has been reported in the literature for children acquiring phonology normally, /s/ occurred earliest in the word-final position, appearing in word-initial position only several weeks later. Two word-medial, or intervocalic, contexts were compared: (a) monomorphemic words in which /s/ is word- and morpheme-medial (e.g., lasso); and (b) bimorphemic words in which /s/ is word-medial but morpheme-final (e.g., missing). In this latter group, a grammatical inflection or morpheme was added to a morpheme that ends with /s/. Correct responses to the intervocalic position where /s/ occurred at a morpheme boundary (i.e., in inflected morphemes) occurred earlier and more frequently than responses to single-morpheme intervocalic position. The variability of the child's productions over time is examined and discussed.

On the prediction of phonologic generalization learning patterns.

The purpose of this study was to obtain information on six children's misarticulation of consonant clusters in order to illustrate how certain factors influence generalization learning patterns. While all subjects evidenced generalization, individual differences in learning patterns did emerge. These patterns were explained in terms of the following three factors: (1) information about the children's unique knowledge about the phonologic system, (2) the linguistic relationships among sounds, and (3) the interaction of these factors with the treatment target. The implications of this explanation are discussed as they relate to the selection of treatment targets that will facilitate generalization.