Metal recovery from electronic waste: Biological versus chemical leaching for copper and gold recovery

Waste electrical and electronic equipment (WEEE) generation is a global problem. Despite the growing awareness and deterring legislation, most of the WEEE is disposed improperly, i.e. landfilled or otherwise shipped overseas, and treated in sub-standard conditions. Informal recycling of WEEE has catastrophic effects on humans and the environment. WEEE contains considerable quantities of valuable metals such as base metals, precious metals and rare earth elements (REE). Metal recovery from WEEE is conventionally carried out by pyrometallurgical and hydrometallurgical methods. In this PhD research, novel metal recovery technologies from WEEE are investigated. Using acidophilic and cyanide-generating bacteria, copper and gold were removed from crushed electronic waste with removal efficiencies of 98.4 and 44.0%, respectively. The leached metals in solution were recovered using sulfidic precipitation and electrowinning separation techniques. Finally, a techno-economic assessment of the technology was studied. This research addresses the knowledge gap on two metal extraction approaches, namely chemical and biological, from a secondary source of metals. The essential parameters of the selective metal recovery processes, scale-up potential, techno-economic and sustainability assessment have been studied

The Sustainable strategy for small and medium sized enterprises: The relationship between mission statements and performance

The study aims to contribute to the literature by empirically examining the relationship between small and medium sized enterprises’ (SMEs) mission statements and their performance in sustainable strategy formulation. Although it seems that there is a relatively vast amount of research with regard to mission statements of companies, very few studies have focused on the relationship between mission statements and performance. When these few studies are taken into consideration, it is difficult to reach any overall conclusion since their findings are mixed and inconclusive. To achieve this aim, 3034 SMEs operating in organized industrial zones in Turkey were examined via a survey approach. In order to investigate the relationships among the variables, nine categories of mission statements as independent variables and four performance indicators (financial, market, production, and overall) as dependent variables were analyzed through logistic regression. This study identified three mission components, (1) survival, growth, and profit; (2) philosophy and values; and (3) public image, as the common independent variables in explaining the performance of SMEs. Survival, growth, and profit is the most frequently observed mission component regardless of the subsector differentiation in the entire sample, which reflects the significance of business sustainability for SMEs in the Turkish manufacturing context. Besides, among all performance indicators, SMEs’ market performance was found to be the lowest when compared to other performance indicators (financial, production, overall). Although the firms were placed in different manufacturing subsectors, similar mission statements were highlighted so that the discourse similarity might be considered as evidence of isomorphism characteristics for SMEs

The Prevalence and Comorbidity Rates of ADHD Among School-Age Children in Turkey

Objective: The aim of the present study was to explore the prevalence and comorbidity rates of ADHD in a community sample of school-age children. Method: Participants were 1,508 children aged 6 to 14 years. Parents and teachers of each child completed the Turgay Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) Disruptive Behavior Disorders Rating Scale (T-DSM-IV-S). Screen-positive cases were interviewed using the Schedule for Affective Disorders and Schizophrenia for School-Age Children–Present and Lifetime Version (K-SADS-PL). Diagnoses were based on DSM-IV criteria. Results: The prevalence rate of ADHD was 8%. Children from extended families had extremely high rates (46.4%) of ADHD. Sixty percent of children with ADHD had one or more comorbid diagnoses. The most common comorbidities were learning disorders (35.7%) and oppositional defiant disorder (22.6%). Conclusion: The prevalence and comorbidity rates of ADHD in school-age children in Turkey are similar to those found in previous studies in other countries. © 2015 SAGE Publications

in Turkey

Objective: The aim of the present study was to explore the prevalence and comorbidity rates of ADHD in a community sample of school-age children. Method: Participants were 1,508 children aged 6 to 14 years. Parents and teachers of each child completed the Turgay Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) Disruptive Behavior Disorders Rating Scale (T-DSM-IV-S). Screen-positive cases were interviewed using the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version (K-SADS-PL). Diagnoses were based on DSM-IV criteria. Results: The prevalence rate of ADHD was 8%. Children from extended families had extremely high rates (46.4%) of ADHD. Sixty percent of children with ADHD had one or more comorbid diagnoses. The most common comorbidities were learning disorders (35.7%) and oppositional defiant disorder (22.6%). Conclusion: The prevalence and comorbidity rates of ADHD in school-age children in Turkey are similar to those found in previous studies in other countries.C1 [Zorlu, Adil] Izmir Tepecik Training & Res Hosp, Izmir, Turkey.[Unlu, Gulsen; Cakaloz, Burcu; Buber, Ahmet] Pamukkale Univ, Fac Med, Dept Child & Adolescent Psychiat, TR-20070 Denizli, Turkey.[Zencir, Mehmet] Pamukkale Univ, Fac Med, Dept Publ Hlth, Denizli, Turkey.[Isildar, Yetis] Sami Ulus Training & Res Hosp, Ankara, Turkey

Cooperative effects of field traffic and organic matter treatments on some compaction-related soil properties

Soil compaction is a common problem of mineral soils under conventional tillage practices. Organic matter addition is an efficient way of reducing the effects of field traffic in soil compaction. The aim of this study was to investigate the effects of number of tractor passes (one, three, and five) on depth-dependent (0–10 and 10–20 cm) penetration resistance, bulk density, and porosity of clay-textured soil (Typic Xerofluvent) under organic vegetable cultivation practices in the 2010–2013 growing seasons. Fields were treated with farmyard manure (FYM, 35 t ha−1), green manure (GM; common vetch, Vicia sativa L.), and conventional tillage (CT). The number of tractor passes resulted in increases in bulk density and penetration resistance (CT > GM > FYM), whereas the volume of total and macropores decreased. The maximum penetration resistance (3.60 MPa) was recorded in the CT treatment with five passes at 0–10 cm depth, whereas the minimum (1.64 MPa) was observed for the FYM treatment with one pass at 10–20 cm depth. The highest bulk density was determined as 1.61 g cm−3 for the CT treatment with five passes at 10–20 cm depth; the smallest value was 1.25 g cm−3 in the FYM treatment with only one pass at 0–10 cm depth. The highest total and macropore volumes were determined as 0.53 and 0.16 cm3 cm−3 respectively at 0–10 cm depth for the FYM treatment with one pass. The volume of micropores (0.38 cm3 cm−3) was higher at 0–10 cm depth for the FYM treatment with three passes. It can be concluded that organic pre-composted organic amendment rather than green manure is likely to be more efficient in mitigating compaction problems in soil

DNA damage in intact cells induced by bacterial metabolites of chloramphenicol

Four chloramphenicol (CAP) metabolites known to be produced by intestinal bacteria were examined with respect to their capacity to induce DNA damage in intact cells. The induction of DNA single‐strand breaks in Raji cells, activated human lymphocytes, and human marrow cells was assayed by the alkaline elution technique. One of the four compounds tested, dehydro‐CAP, was capable of inducing DNA single‐strand breaks in all three cell systems at concentrations of 10−4 M. This effect is comparable to that observed previously with nitroso‐CAP, the nitroreduction intermediate of CAP. The nitroreduction of dehydro‐CAP by human bone marrow cell homogenate was detected by the production of the corresponding amino derivative amounting to 5.6 × 10−5M from 2 × 10−3M substrate under aerobic conditions. In sharp contrast, nitroreduction of CAP by bone marrow could not be demonstrated. The genotoxicity of dehydro‐CAP, its relative stability compared to the nitroso‐CAP, and its nitroreducibility by bone marrow suggest that this bacterial metabolite of CAP may play a key role as a mediator of aplastic anemia in the predisposed host

Chloramphenicol-induced bone marrow injury: possible role of bacterial metabolites of chloramphenicol

To explore the potential role of some bacterial metabolites of chloramphenicol (CAP) in CAP-induced hematotoxicity, we examined their cytotoxic effects on bone marrow cells in vitro using a number of cytotoxicity parameters. Among the metabolites tested, dehydro-CAP (DHCAP) and p-nitrophenyl-2-amino-3 hydroxypropanone-HCI (NPAP) were more toxic than CAP. DHCAP was at least as toxic as nitroso-CAP. At concentrations of less than or equal to 10(-4) mol/L, DHCAP caused total irreversible inhibition of myeloid colony (CFU-GM) growth and 80% inhibition of DNA synthesis in human bone marrow. Incubation of human bone marrow cells with 10(-4) mol/L nitroso-CAP or DHCAP for 24 hours resulted in 75% and 65% cell death respectively. Although DHCAP was 10- to 20-fold more cytotoxic than CAP, it was only one third as effective in inhibiting mitochondrial protein synthesis, indicating that DHCAP exerts its toxic effect by alternate mechanisms. The cytotoxicity of DHCAP and its relative stability, compared to the unstable nitroso CAP, suggest that this bacterial metabolite of CAP, and possibly others, may play a significant role in CAP-induced hematotoxicity