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Selected AbstractsPrimary Cutis Verticis Gyrata and Scalp Reduction in One Stage with Multiple Pinwheel Flaps (Revisited)DERMATOLOGIC SURGERY, Issue 7 2008AYKUT MISIRLIOGLU MD First page of article [source] Curettage prior to Mohs' Micrographic Surgery for Previously Biopsied Nonmelanoma Skin Cancers: What Are We Curetting?DERMATOLOGIC SURGERY, Issue 1 2005Comparative Study, Prospective, Retrospective Background Curettage prior to excision and Mohs' micrographic surgery for nonmelanoma skin cancer is performed based on the assumption that the curette will remove softer, more friable tumor-infiltrated dermis and leave structurally intact normal skin. This assumption, however, has not been objectively examined in the dermatologic surgery literature. Objective We performed a study to examine the ability of curettage to selectively remove and delineate nonmelanoma skin cancer prior to Mohs' micrographic surgery. Methods The study included 150 previously biopsied basal cell and squamous cell carcinomas less than 1.5 cm in size. We conducted (1) a retrospective study of 50 tumors curetted prior to Mohs' surgery by a surgeon who routinely curettes preoperatively; (2) a prospective study in which a surgeon who routinely does not curette preoperatively curetted 50 tumors prior to Mohs' surgery; and (3) a comparative historical group of 50 noncuretted tumors treated with Mohs' surgery by the latter surgeon. All curetted tissue was evaluated histologically. Results Only 50% of the curetted tissue demonstrated the presence of tumor in the curettings, but in 76% of these, the curette left residual tumor at the surgical margins. Of the other 50% in which the curette removed only non,cancer-containing skin, 34% had tumor present at the surgical margin. Overall, the curette removed tumor, leaving no residual tumor at the surgical margins in only 12% of lesions. Comparison with historical noncuretted tumors operated on by the same surgeon showed that curettage did not affect the mean number of stages or the proportion of tumors requiring more than one stage for histologic clearance. Conclusion Although curettage may be helpful in debulking friable skin prior to Mohs' micrographic surgery, it does not reliably delineate the extent of a tumor. MING H. JIH, MD, PHD, PAUL M. FRIEDMAN, MD, LEONARD H. GOLDBERG, MD, AND ARASH KIMYAI-ASADI, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source] Reconstruction of the columella using the prefabricated reverse flow submental flap: A case reportHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 7 2006Onder Tan MD Abstract Background. The reconstruction of columellar defects is still a challenging procedure because of limited local and regional flap options and the characteristics of the anatomy of this site. Although a number of methods are available to repair nasal columella defects, no treatment of choice ensuring an excellent texture- and color-matched tissue in one stage has been determined to date. Method. In this case, we used a reverse-flow submental island flap prefabricated with the costal cartilage for the reconstruction of a complex columellar defect. Result. The flap survived completely with reversible venous congestion. The cosmetic result and nasal respiratory function were acceptable during the follow-up time of 6 months. Conclusion. We propose that the prefabricated reverse submental flap may be an alternative among the surgical options for columellar defects. This flap may also be considered in the reconstructive repertoire of other composite defects of the head and neck region. © 2006 Wiley Periodicals, Inc. Head Neck, 2006 [source] Functional reconstruction of the lateral face after ablative tumor resection: Use of free muscle and musculocutaneous flapsHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 10 2001Tugrul Maral MD Abstract Background Wide resection of tumors of the middle third of the face often results in complex three-dimensional defects and facial paralysis either due to removal of the facial nerve within the tumoral tissue or to extensive resection of the facial muscles. Methods We report the cases of three patients who underwent wide excision of tumors of the cheek region, operations that resulted in tissue defects and facial palsy. Defect reconstruction and facial reanimation was accomplished in one stage through functional muscle transplantation. Results Follow-up of more than 1 year showed good symmetry at rest and reanimation of the corner of the mouth in all cases, but one patient, in which the ipsilateral facial main trunk was used as motor nerve supply to the transplanted muscle, developed significant muscle contracture and binding of the cheek skin. Conclusions Every effort should be made to optimize the functional and cosmetic outcomes of neurovascular muscle transfers through precise planning and careful execution of the intricate details of the surgical technique for muscle transplantation. © 2001 John Wiley & Sons, Inc. Head Neck 23: 836,843, 2001. [source] A seven-gene signature (cirrhosis risk score) predicts liver fibrosis progression in patients with initially mild chronic hepatitis C,HEPATOLOGY, Issue 4 2009Moira Marcolongo Fibrosis progression is the main determinant of liver disease outcome in chronic hepatitis C, being influenced by environmental and host factors. Recently, a cirrhosis risk score (CRS) based on seven single-nucleotide polymorphisms was proposed as genetic predictor of cirrhosis in hepatitis C. To assess the role of CRS in predicting fibrosis progression in patients with initially no or minimal to moderate fibrosis, we investigated 271 untreated patients with chronic hepatitis C having initial liver biopsy showing METAVIR stage F0 (n = 104), F1 (n = 101), or F2 (n = 59) who had been followed up without antiviral therapies for at least 60 months (mean 108.5 ± 71.5 months) and had a liver biopsy at the end of this observation period. Of these, 24.4% showed no histologic progression, 75.6% progressed by at least one stage, 45.0% progressed by at least two stages, and 10.3% progressed by more than two stages. The mean CRS was significantly higher (P = 0.005) in patients with fibrosis progression compared with those without progression, and this difference was particularly evident (P = 0.002) with F0 on initial biopsy. Mean CRS scores were not associated with degree of fibrosis progression. The relative risk of fibrosis progression increased with increasing CRS values. This association was significant in males but not in females and was most evident in males with F0 at initial biopsy (odds ratio 16.5, 95% confidence interval 1.6,166; P= 0.02) in the presence of high CRS. Multivariate analysis confirmed the significant association of CRS score with fibrosis progression. The predictive value of CRS was confirmed in hepatitis C virus patients admitting significant alcohol intake. Conclusion: Host genetics defined by CRS predict fibrosis progression in males with initially mild chronic hepatitis C and may become a useful parameter for prognostic evaluation and treatment decision. (HEPATOLOGY 2009.) [source] Risk factors for fibrosis progression in HIV/HCV coinfected patients from a retrospective analysis of liver biopsies in 1985,2002HIV MEDICINE, Issue 5 2006M Schiavini Objectives To identify predictive factors for moderate/severe liver fibrosis and to analyse fibrosis progression in paired liver biopsies from HIV-positive patients with chronic hepatitis C virus (HCV) infection. Methods HIV/HCV coinfected patients followed at the 2nd Department of Infectious Diseases of L. Sacco Hospital in Milan, Italy, with at least one liver biopsy specimen were retrospectively evaluated. Results A total of 110 patients were enrolled in the study. In a univariate analysis, predictive factors of Ishak,Knodell stage ,3 were a history of alcohol abuse [odds ratio (OR) 3.6, P=0.004], alanine aminotransferase level >100 IU/L at biopsy (OR 2.4, P=0.05), necro-inflammatory grade ,9 (OR 37.14, P<0.0001) and CD4 count <350 cells/,L at nadir (OR 5.3, P=0.05). In a multivariate analysis, age >35 years (OR 3.19, P=0.04) and alcohol abuse (OR 4.36, P=0.002) remained independently associated with Ishak,Knodell stage. Paired liver biopsies were available in 36 patients; 18 showed an increase of at least one stage in the subsequent liver biopsy. Either in a univariate or in a multivariate analysis, a decrease of CD4 cell count of more than 10% between two biopsies (OR 6.85, P=0.002) was significantly associated with liver fibrosis progression. Conclusion Our findings highlight the relevance of encouraging a withdrawal of alcohol consumption in people with chronic HCV infection and of carrying out close follow-up of patients, especially if they are more than 35 years old. It is therefore mandatory to evaluate HIV/HCV coinfected patients for anti-HCV treatment and to increase CD4 cell count through antiretroviral therapy in order to reduce the risk of fibrosis progression and to slow the evolution of liver disease. [source] Screening for depression and anxiety: correlates of non-response and cohort attrition in the Netherlands Study of Depression and Anxiety (NESDA)INTERNATIONAL JOURNAL OF METHODS IN PSYCHIATRIC RESEARCH, Issue 4 2009Willem Jan Van Der Veen Abstract A major problem in the analysis of attrition of cohorts in studies on mental health problems is that data on those who do not participate at the outset of a study are largely unavailable. It is not known how underlying psychopathology affects the first stages of screening where non-response and selectivity are usually highest. This article presents results of one of the centres of the Netherlands Study of Depression and Anxiety (NESDA), a longitudinal study aimed at describing the long-term course and consequences of depression and anxiety disorders. The aim is to describe the different ways of attrition during the first NESDA-wave in a cohort of patients aged 18,65 years of the Registration Network Groningen and to analyse whether attrition is related to gender, age and psychopathology as recorded in general practice. The attrition of the study cohort (n = 8475) was highest during the first stages, eventually leading to a population of 169 patients only who participated in the full NESDA-programme. Probabilities of transition from one stage of the screening process to the next were regressed on selected background variables using binary logistic regression. Correlates of participation were being female and being older (>40). Psychopathology was an important variable in the formation of the initial sample cohort, but only had a weak influence on patient response to the screening questionnaire. Study design factors had a stronger impact on the changing composition of the cohort at each screening stage compared to patient factors. Copyright © 2009 John Wiley & Sons, Ltd. [source] The European Policy for the Development of an Information Society: the Right Path?,JCMS: JOURNAL OF COMMON MARKET STUDIES, Issue 4 2008JOSÉ LUIS GÓMEZ-BARROSO The end of 2005 marked the closure of one stage in the European strategy for the promotion of the information society (the eEurope programme) and the start of the next one (i2010). This seems to be a good time for assessing the results achieved to date by the community policy in this area and analysing whether the correct approach has been adopted. Despite the satisfaction shown in certain official appraisals, the picture resulting from consulting different classifications globally measuring the adaptation of countries to the information society is not that optimistic. Only the European Union leaders in this field (the Nordic countries) have improved their positions, broadening the gap with the rest: western European countries have lost ground (or at least have not improved) in the rankings, the southern countries do not seem to have corrected their deficiencies and the indices for the new Member States have not evolved as expected or have even deteriorated in some cases. Even though becoming one of the most competitive and dynamic knowledge-based economies in the world was the first Leitmotiv of the Lisbon strategy, the interpretation of the documents connected to the definition of the new stage in the strategy led to doubts over whether the European Union has a clear notion on the course of action to take in order to make progress on the information society a matter of priority. [source] Patterns of mortality for each life-history stage in a population of the endangered New Zealand stitchbirdJOURNAL OF ANIMAL ECOLOGY, Issue 4 2009Matthew Low Summary 1Using data from 396 breeding attempts over an 8-year period, we investigated age- and stage-specific survival rates and their modifying factors in a closed island population of the New Zealand stitchbird (or hihi, Notiomystis cincta Du Bus). 2Survival probability generally increased over time; however, at each life-history transition, survival in the new stage started lower than at the end of the previous stage, creating a ,saw-tooth' function of age-related survival. 3The probability of an egg hatching was low (0·73 ± 0·01): most likely a consequence of genetic bottlenecks previously endured by this population. There was strong support for a positive relationship between hatching rate and the subsequent survival of the female parent, and hatching success declining for females > 4 years old. 4Nestling survival probability increased as a function of brood size and days since hatching, and decreased relative to daily maximum ambient temperature and hatching date. Support for models including ambient temperature was greater than for other covariates, with the majority of this temperature-mediated survival effect being restricted to the early nestling stage. 5Fledglings had low survival rates in the first two weeks after leaving the nest, with post-fledging survival related to the fledgling's mass. Two months after fledging, juvenile survival probability plateaued and remained relatively constant for the following autumn, winter and spring/summer breeding season. There was no effect of sex or season on adult survival probability. However, there was strong support for age-specific variation in adult survival, with survival likelihood increasing during the first four years before showing evidence of a senescence decline. 6Within-stage survival increases were likely related to stage-specific selection pressures initially weeding out individuals of poorer phenotypes for the environment specific to each life-history stage. Such a mechanism explains the initial high mortality at life-history transitions; a well-adapted phenotype for one stage may not necessarily be so well adapted for subsequent stages. These patterns are not only valuable for examining life-history theory, but also for understanding the regulation of vital rates in an endangered species and providing a basis from which better population management models and harvesting regimes can be derived. [source] Thermal decomposition kinetics of poly(nButMA- b -St) diblock copolymer synthesized by ATRPJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2009Adnan KurtArticle first published online: 8 JUN 200 Abstract The reaction mechanism of decomposition process and the kinetic parameters of the poly(n -butyl methacrylate-b-styrene), poly(nButMA-b-St), diblock copolymer synthesized by atom transfer radical polymerization (ATRP) were investigated by thermogravimetric analysis (TGA) at different heating rates. TGA curves showed that the thermal decomposition occurred in one stage. The apparent activation energies of thermal decomposition for copolymer, as determined by the Kissinger's, Flynn,Wall,Ozawa and Tang methods, which does not require knowledge of the reaction mechanism (RM), were 112.52, 116.54, and 113.41 kJ/mol, respectively. The experimental results were compared with master plots, in the range of the Doyle approximation. Analysis of experimental results suggests that in the conversion range studied, 3,18%, the actual RM is an A2 sigmoidal type. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] The intra-oral translocation of periodontopathogens jeopardises the outcome of periodontal therapyJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 6 2001A review of the literature Abstract Background: Although periodontitis has a multi-factorial aetiology, the success of its therapy mainly focuses on the eradication/reduction of the exogenous/endogenous periodontopathogens. Most of the species colonise several niches within the oral cavity (e.g. the mucosae, the tongue, the saliva, the periodontal pockets and all intra-oral hard surfaces) and even in the oro-pharyngeal area (e.g., the sinus and the tonsils). Methods: This review article discusses the intra-oral transmission of periodontopathogens between these niches and analyses clinical studies that support the idea and importance of such an intra-oral translocation. Results and conclusions: Based on the literature, the oro-pharyngeal area should indeed be considered as a microbiological entity. Because untreated pockets jeopardise the healing of recently instrumented sites, the treatment of periodontitis should involve "a one stage approach" of all pathologic pockets (1-stage full-mouth disinfection) or should at least consider the use of antiseptics during the intervals between consecutive instrumentations, in order to prevent a microbial translocation of periodontopathogens during the healing period. For the same reason, regeneration procedures or the local application of antibiotics should be postponed until a maximal improvement has been obtained in the remaining dentition. This more global approach offers significant additional clinical and microbiological benefits. Zusammenfassung Grundlagen: Obwohl die Parodontitis eine multifaktorielle Ätiologie hat, konzentriert sich der Erfolg ihrer Therapie hauptsächlich auf die Eliminierung/Reduktion der exogenen/endogenen Parodontalpathogene. Die meisten dieser Spezies kolonisieren verschiedene Nischen innerhalb der Mundhöhle (z.B. die Schleimhäute, die Zunge, den Speichel, die parodontalen Taschen und alle intraoralen Hartgewebe) und sogar den oro-pharyngealen Bereich (z.B. die Nebenhöhlen und die Tonsillen). Methoden: Dieser Übersichtartikel diskutiert die intraorale Übertragung von Parodontalpathogenen zwischen diesen Nischen und analysiert klinische Studien, die die Idee und Wichtigkeit dieser intraoralen Übertragung unterstützen. Ergebnisse und Schlussfolgerung: Auf der Grundlage der Literatur sollte der oro-pharyngeale Bereich in der Tat als eine mikrobiologische Einheit angesehen werden. Weil unbehandelte Taschen die Heilung von kürzlich instrumentierten Stellen gefährden, sollte die Behandlung der Parodontitis ein einzeitiges Vorgehen bei allen pathogenen Taschen beinhalten (einzeitige vollständige Mundhöhlen-Desinfektion). Oder es sollten wenigsten die Verwendung von antiseptischen Mitteln während der Intervalle zwischen aufeinanderfolgenden Instrumentierungen erwogen werden, um die mikrobielle Übertragung von Parodontalpathogenen während der Heilungsphase zu verhindern. Aus dem gleichen Grunde sollten regenerative Maßnahmen oder die lokale Applikation von Antibiotika so lange verschoben werden, bis eine maximale Verbesserung im restlichen Gebiss erzielt wurde. Dieser globalere Ansatz liefert zusätzliche signifikante klinische und mikrobiologische Vorteile. Résumé Origine: Bien que la parodontite ait une étiologie multifactorielle, le succès de son traitement repose principalement sur l'éradication/réduction des bactéries parodontopathogènes exogènes/endogènes. La plupart des espèces colonisent plusieurs niches au sein de la cavité buccale (par exemple, les muqueuses, la langue la salive, les poches parodontales et toutes les surfaces dures intraorales), et même dans la zone oro-pharyngée (par example, les sinus et les amygdales). Méthodes: Cette revue critique discute la transmission intra-buccale des pathogènes parodontaux entre ces niches et analyse les études clinique qui soutiennent l'idée et l'importance d'une telle translocation intra-buccale. Résultats et conclusions: D'après la littérature, la zone oro-pharyngée peut vraiment être considérée comme une entité microbiologique. Puisque les poches non traitées compromettent la cicatrisation des sites récemment instrumentés, le traitement de la parodontite devrait impliquer une approche en une étape de toutes les poches pathologiques (désinfection de toute la bouche en une étape) ou devrait au moins considérer l'utilisation d'antiseptiques pendant les intervals entre deux instrumentations successives, de façon à prévenir une translocation bactérienne des pathogènes parodontaux pendant la période de cicatrisation. Pour la même raison, les procédures de régénération ou les applications locales d'antibiotiques devraient être remises jusqu'à ce qu'une amélioration maximale ait été obtenue sur le reste de la denture. Cette approche plus globale donne des bénéfices cliniques et microbiologiques supplémentaires significatifs. [source] Adoption of agricultural innovations as a two-stage partial observability processAGRICULTURAL ECONOMICS, Issue 3 2003Efthalia Dimara Innovation adoption; Organic agriculture; Partial observability Abstract In this paper, we reconsider the appropriateness of certain statistical analyses in innovation adoption studies and suggest that partial observability models may sometimes be more useful. The proposed models allow for a flexible specification of the process of adoption from one stage to two stages, facilitate the modelling of non-adopters and remedy the violation of the assumption of full information. An application to the adoption of organic cultivation in Greece demonstrates the relative merits of the proposed analysis. [source] Lower genital tract lesions requiring surgical intervention in girls: Perspective from a developing countryJOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 10 2009Sebastian O Ekenze Aim: To determine the spectrum, outcome of treatment and the challenges of managing surgical lesions of lower genital tract in girls in a low-resource setting. Method: Retrospective study of 87 girls aged 13-years and younger, with lower genital tract lesions managed between February 2002 and January 2007 at the University of Nigeria Teaching Hospital, Enugu, southeastern Nigeria. Clinical charts were reviewed to determine the types, management, outcome of treatment and management difficulties. Results: The median age at presentation was 1 year (range 2 days,13 years). Congenital lesions comprised 67.8% and acquired lesions 32.2%. The lesions included: masculinised external genitalia (24), vestibular fistula from anorectal malformation (23), post-circumcision labial fusion (12), post-circumcision vulval cyst (6), low vaginal malformations (6), labial adhesion (5), cloacal malformation (3), bifid clitoris (3) urethral prolapse (3), and acquired rectovaginal fistula (2). Seventy-eight (89.7%) had operative treatment. Procedure related complications occurred in 19 cases (24.4%) and consisted of surgical wound infection (13 cases), labial adhesion (4 cases) and urinary retention (2 cases). There was no mortality. Overall, 14 (16.1%) abandoned treatment at one stage or another. Challenges encountered in management were inadequate diagnostic facilities, poor multidisciplinary collaboration and poor patient follow up. Conclusion: There is a wide spectrum of lower genital lesion among girls in our setting. Treatment of these lesions may be challenging, but the outcome in most cases is good. High incidence of post-circumcision complications and poor treatment compliance may require more efforts at public enlightenment. [source] Surgical Appreciation of Robert boyle in the 21st CenturyANZ JOURNAL OF SURGERY, Issue 12 2000D. L. Murphy Robert Boyle was known as the Father of Chemistry. He lived at a time when science and religion were closely linked. It was a pious and puritanical time, but also a time of great enlightenment. His original and paramount thesis, that air has weight, has given us Boyle's gas law. Another of his writings in the Cowlishaw Collection is on religion. It is stated that, at one stage, he was deliberating whether to be a scientist or a priest. Surgical appreciation of Boyle's law has poignant application in scientific methods and research in the 21st century. The development of advanced laparoscopic surgery represents a challenging new era in surgery that was not envisaged by our surgical predecessors. Basic surgical research into the effects of gas pressure on renal function and bowel response will be presented. [source] From Washington Consensus to BeST Consensus for world developmentASIAN-PACIFIC ECONOMIC LITERATURE, Issue 1 2010Keun Lee While the set of liberalising and fiscally conservative development precepts dubbed the ,Washington Consensus' are now discredited as a tool for development, there is as yet no widely adopted or accepted alternative other than references to the ,East Asian model'. In this paper, we distil the essence of the experience of East Asia,of Japan initially, then of Korea and Taiwan, and now of China,in a set of flexible precepts that we suggest underpin the policies and strategies pursued with success by these East Asian economies. In the spirit of proposing an alternative to the Washington Consensus, we suggest that these precepts,pragmatic and known to work,be dubbed the Beijing,Seoul,Tokyo Consensus (or BeST Consensus for development). The essence of this consensus is its focus on capability building, on dynamic transitions from one stage to the next, and on building an institutional platform to capture latecomer effects. We outline what this BeST Consensus might be and discuss why it is that its elements appear to work so well; and whether they can still be applied in the world of 21st-century conditions. [source] A conceptual framework for the colonisation of urban areas: the blackbird Turdus merula as a case studyBIOLOGICAL REVIEWS, Issue 3 2010Karl L. Evans Despite increasing interest in urban ecology the factors limiting the colonisation of towns and cities by species from rural areas are poorly understood. This is largely due to the lack of a detailed conceptual framework for this urbanisation process, and of sufficient case studies. Here, we develop such a framework. This draws upon a wide range of ecological and evolutionary theory and the increasing number of studies of how the markedly divergent conditions in urban and rural areas influence the traits of urban populations and the structure of urban assemblages. We illustrate the importance of this framework by compiling a detailed case study of spatial and temporal variation in the urbanisation of the blackbird Turdus merula. Our framework identifies three separate stages in the urbanisation process: (i) arrival, (ii) adjustment, and (iii) spread. The rate of progress through each stage is influenced by environmental factors, especially human attitudes and socio-economic factors that determine the history of urban development and the quality of urban habitats, and by species' ecological and life-history traits. Some traits can positively influence progression through one stage, but delay progression through another. Rigorous assessment of the factors influencing urbanisation should thus ideally pay attention to the different stages. Urbanisation has some similarities to invasion of exotic species, but the two clearly differ. Invasion concerns geographic range expansion that is external to the species' original geographic range, whilst urbanisation typically relates to filling gaps within a species' original range. This process is exemplified by the blackbird which is now one of the commonest urban bird species throughout its Western Palearctic range. This is in stark contrast to the situation 150 years ago when the species was principally confined to forest. Blackbird urbanisation was first recorded in Germany in 1820, yet some European cities still lack urban blackbirds. This is especially so in the east, where urbanisation has spread more slowly than in the west. The timing of blackbird urbanisation exhibits a marked spatial pattern, with latitude and longitude explaining 76% of the variation. This strong spatial pattern contrasts with the weaker spatial pattern in timing of urbanisation exhibited by the woodpigeon Columba palumbus (with location explaining 39% of the variation), and with the very weak spatial pattern in timing of black-billed magpie Pica pica urbanisation (in which location explains 12% of the variation). Strong spatial patterns in timing of urbanisation are more compatible with the leap-frog urbanisation model, in which urban adapted or imprinted birds colonise other towns and cities, than with the independent urbanisation model, in which urban colonisation events occur independently of each other. Spatial patterns in isolation do not, however, confirm one particular model. Factors relating to the arrival and adjustment stages appear particularly likely to have influenced the timing of blackbird urbanisation. Spatial variation in the occurrence of urban populations and the timing of their establishment creates opportunities to assess the factors regulating urbanisation rates, and how the composition of urban assemblages develops as a result. These are major issues for urban ecology. [source] Precipitation and recovery of metal sulfides from metal containing acidic wastewater in a sulfidogenic down-flow fluidized bed reactorBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009Marisol Gallegos-Garcia Abstract This study reports the feasibility of recovering metal precipitates from a synthetic acidic wastewater containing ethanol, Fe, Zn, and Cd at an organic loading rate of 2.5 g COD/L-day and a COD to sulfate ratio of 0.8 in a sulfate reducing down-flow fluidized bed reactor. The metals were added at increasing loading rates: Fe from 104 to 320 mg/L-day, Zn from 20 to 220 mg/L-day, and Cd from 5 to 20 mg/L-day. The maximum COD and sulfate removals attained were 54% and 41%, respectively. The biofilm reactor was operated at pH as low as 5.0 with stable performance, and no adverse effect over COD consumption or sulfide production was observed. The metals precipitation efficiencies obtained for Fe, Zn, and Cd exceeded 99.7%, 99.3%, and 99.4%, respectively. The total recovered precipitate was estimated to be 90% of the theoretical mass expected as metal sulfides. The precipitate was mainly recovered from the bottom of the reactor and the equalizer. The analysis of the precipitates showed the presence of pyrite (FeS2), sphalerite (ZnS) and greenockite (CdS); no metal hydroxides or carbonates in crystalline phases were identified. This study is the first in reporting the feasibility to recover metal sulfides separated from the biomass in a sulfate reducing process in one stage. Biotechnol. Bioeng. 2009;102: 91,99. © 2008 Wiley Periodicals, Inc. [source] | ||||||||||||||||