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Resultados 3091-3100 de 5,151
Fine particulate matter (PM2.5) in a compost facility: heavy metal contaminations and health risk assessment, Tehran, Iran Texto completo
2018
Kermani, Majid | Farzadkia, Mahdi | Kalantari, RoshanakRezaei | Bahmani, Zohreh
The aim of this study was to evaluate the concentration of PM₂.₅ particles, potential sources, and determination of health risk assessment of heavy metals in various parts of composting facilities of Tehran’s Kahrizak. A total of 60 PM₂.₅ particle samples were collected every 3 days from January to March 2016. To analyze the heavy metals, inductively coupled plasma atomic emission spectroscopy (ICP-AES) was applied. SEM-EDX analysis indicated that metals of Al, Si, Mg, Na, Au, S, Ca, K, and Co were dominant in the structure of particles. The concentration of PM₂.₅ was found to be the highest in the final processing site (c), followed by primary processing site (a) and the aerated site (b). The mean concentrations of Al and Fe in all sampling sites of a, b, and c were 7.46 ± 2.73, 1.48 ± 0.59, 24.30 ± 8.23 μg/m³ and 4.97 ± 2.83, 1.33 ± 0.48, 16.48 ± 7.36, respectively. The enrichment factor order of the trace elements was as follows: Cd > As > Pb > Zn > Cu > V > Cr > Ni > Mn > Fe > Al, with the highest EF value exceeding 10,000 for Cd at the a site. For all sampling sites in composting facilities, the cancer risk was more than > 1 × 10⁻⁴ as posed by the total of five carcinogenic metals (Pb, Cr, As, Ni, and Cd), indicating that risk factors were not negligible.
Mostrar más [+] Menos [-]Lifestyle chemical carcinogens associated with mutations in cell cycle regulatory genes increases the susceptibility to gastric cancer risk Texto completo
2018
Yadav, Ravi Prakash | Ghatak, Souvik | Chakraborty, Payel | Lalrohlui, Freda | Kannan, Ravi | Kumar, Rajeev | Pautu, Jeremy L. | Zomingthanga, John | Chenkual, Saia | Muthukumaran, Rajendra | Senthil Kumar, Nachimuthu
In the present study, we correlated the various lifestyle habits and their associated mutations in cell cycle (P21 and MDM2) and DNA damage repair (MLH1) genes to investigate their role in gastric cancer (GC). Multifactor dimensionality reduction (MDR) analysis revealed the two-factor model of oral snuff and smoked meat as the significant model for GC risk. The interaction analysis between identified mutations and the significant demographic factors predicted that oral snuff is significantly associated with P21 3′UTR mutations. A total of five mutations in P21 gene, including three novel mutations in intron 2 (36651738G > A, 36651804A > T, 36651825G > T), were identified. In MLH1 gene, two variants were identified viz. one in exon 8 (37053568A > G; 219I > V) and a novel 37088831C > G in intron 16. Flow cytometric analysis predicted DNA aneuploidy in 07 (17.5%) and diploidy in 33 (82.5%) tumor samples. The G2/M phase was significantly arrested in aneuploid gastric tumor samples whereas high S-phase fraction was observed in all the gastric tumor samples. This study demonstrated that environmental chemical carcinogens along with alteration in cell cycle regulatory (P21) and mismatch repair (MLH1) genes may be stimulating the susceptibility of GC by altering the DNA content level abnormally in tumors in the Mizo ethic population.
Mostrar más [+] Menos [-]Improvement of ternary fuel combustion with various injection pressure strategies in a toroidal re-entrant combustion chamber Texto completo
2018
Venu, Harish | Dinesh Babu, M.
The present experimental work focuses on the influence injection pressure and toroidal re-entrant combustion chamber in a single cylinder diesel engine fuelled with ternary fuel (diesel-biodiesel-ethanol) blend. Ternary fuel (TF) is prepared by blending 70% diesel, 20% biodiesel, and 10% ethanol blends and its fuel properties were investigated and compared with diesel fuel. Since the physic-chemical properties of TF are well behind the diesel fuel, it is proposed to be blended with 20 ppm alumina nano additives which act as an ignition enhancer and catalytic oxidizer. The resulting fuel mixture (TF + 20 ppm alumina additive) is named as high performance fuel (HPF). Experimentations were conducted on HPF subjected to various injection pressures of 18 MPa, 20 MPa, 22 MPa, and 24 MPa respectively and are operated in toroidal re-entrant chamber geometry (TG) at an injection timing of 22 ᵒbTDC. From experimentation, it was identified that, for TG-HPF, higher injection pressure of 22 MPa ensued highest BTE (Brake Thermal Efficiency) of 35.5% and lowest BSEC (Brake Specific Fuel Consumption) of 10.13 MJ/kWh owing to the pooled effect of higher swirl formation, improved atomization enhanced evaporation rate, and better air-fuel mixing. Emission wise TG-HPF operated at 22 MPa lowered the HC (hydrocarbon), CO (carbon monoxide), and smoke emissions by 18.88%, 7.19%, and 5.02%, but with marginally improved NOx (oxides of nitrogen) and CO₂ (carbon dioxide) emissions by 3.92% and 3.89% respectively. In combustion point of view, it is observed that injection pressure increased the cylinder pressure, heat release rate (HRR), and cumulative heat release rate (CHRR) by 5.35%, 5.08%, and 3.38% respectively indicating improved combustion rate as a result of enhanced atomization, evaporation, and high turbulence inducement. Overall, it is concluded that operating the ternary fuel at 22 MPa injection pressure at toroidal re-entrant combustion chamber results in improved performance and minimized emissions.
Mostrar más [+] Menos [-]Removal of cadmium in aqueous solution using wheat straw biochar: effect of minerals and mechanism Texto completo
2018
Liu, Li | Fan, Shisuo
The biochars were produced from wheat straw (WSBC) at different pyrolytic temperatures. Biochars were characterized by multiple instrumental techniques and were applied to remove Cd from aqueous solution. The removal mechanism was explored, and the quantitative information regarding the relative contribution of related mechanisms to Cd sorption on biochars was provided. The results showed that pseudo-second-order kinetic model, TC (two-compartment) model, and Freundlich isotherm could well fit the process of Cd sorption on biochars. The sorption could be divided into fast and slow adsorption stages. The order of the Cd removal capacity by biochar was WSBC700 > WSBC500 > WSBC300. Adsorption amount of Cd by biochar reduced when the biochar was rinsed with 1.0 M HCl, which indicated that acid-soluble minerals in biochar played an important role during the Cd removal process, especially for the biochar obtained at high pyrolytic temperature. Various equipments were used to investigate the interaction mechanism between biochar and Cd. Mineral precipitation, surface complexation, and cation-π interaction were the main mechanisms of Cd sorption on the biochars. The contribution of cation-π mechanism was in the range of 25.42–48.58%, 2.18–19.30% for surface complexation and 32.12–72.41% for mineral precipitation, respectively. The pyrolytic temperature significantly influenced the removal capacity and mechanism of Cd on biochars. The cation-π mechanism was predominant for biochar obtained at lower pyrolytic temperature. However, mineral precipitation mechanism played a crucial role for biochar obtained at high pyrolytic temperature. These results are helpful for the design or screening of “engineered biochar” to act as sorbents to remove or immobilized Cd in polluted soil or water. Graphical abstract ᅟ
Mostrar más [+] Menos [-]Living in a Mediterranean city in 2050: broadleaf or evergreen ‘citizens’? Texto completo
2018
Cotrozzi, Lorenzo | Remorini, Damiano | Pellegrini, Elisa | Guidi, Lucia | Nali, Cristina | Lorenzini, Giacomo | Massai, Rossano | Landi, Marco
The predicted effects of global change (GC) will be exacerbated in the more densely populated cities of the future, especially in the Mediterranean basin where some environmental cues, such as drought and tropospheric ozone (O₃) pollution, already mine seriously plant survival. Physiological and biochemical responses of a Mediterranean, evergreen, isohydric plant species (Quercus ilex) were compared to those of a sympatric, deciduous, anisohydric species (Q. pubescens) under severe drought (20% of the effective daily evapotranspiration) and/or chronic O₃ exposure (80 ppb for 5 h day⁻¹ for 28 consecutive days) to test which one was more successful in those highly limiting conditions. Results show that (i) the lower reduction of total leaf biomass of Q. ilex as compared to Q. pubescens when subjected to drought and drought × O₃ (on average −59 vs −70%, respectively); (ii) the steeper decline of photosynthesis found in Q. pubescens under drought (−87 vs −81%) and drought × O₃ (−69 vs −59%, respectively); (iii) the increments of malondialdehyde (MDA) by-products found only in drought-stressed Q. pubescens; (iv) the impact of O₃, found only in Q. pubescens leaves and MDA, can be considered the best probes of the superiority of Q. ilex to counteract the effect of mild-severe drought and O₃ stress. Also, an antagonistic effect was found when drought and O₃ were applied simultaneously, as usually happens during typical Mediterranean summers. Our dataset suggests that on future, the urban greening should be wisely pondered on the ability of trees to cope the most impacting factors of GC, and in particular their simultaneity.
Mostrar más [+] Menos [-]Supplementing dietary rosemary (Rosmarinus officinalis L.) powder and vitamin E in broiler chickens: evaluation of humoral immune response, lymphoid organs, and blood proteins Texto completo
2018
Rostami, Hossein | Seidavi, Alireza | Dadashbeiki, Mohammad | Asadpour, Yadollah | Simões, João | Shah, AssarAli | Laudadio, Vito | Losacco, Caterina | Perillo, Antonella | Tufarelli, Vincenzo
The aim of the present study was to evaluate the effect rosemary (Rosmarinus officinalis L.) powder (RP) and vitamin E (VE) at different levels on humoral immunity of broilers during a 42-day production cycle. A total of 270 1-day-old male chicks were assigned to nine groups with three replicates of ten birds each, and diets were supplemented with 0, 0.5, or 1.0% RP and 0, 100, or 200 mg/kg VE, respectively. Commercial-inactivated vaccines against avian influenza (AI) and Newcastle disease (ND) viruses, and living infectious bronchitis virus (IBV) vaccine were administered by spray method. Sheep red blood cells (SRBC) were administered subcutaneously. Blood samples were collected from birds 1 week after each vaccination to determine antibody titers. At the 42nd day, blood samples were also assessed for globulin level, and lymphoid tissues (thymus, spleen, and bursa) were weighed. Neither antibody titers against viruses nor lymphoid tissues weight were affected by RP and/or VE (P > 0.05) treatments. However, broilers supplemented with 0 mg/kg of VE had lower antibody titers against SRBC than those fed 100 mg/kg of VE (P < 0.05) at the 24th day. A significant RP × VE interaction effect (P < 0.05) on plasma globulin level was observed. The findings of our study suggest that dietary RP and VE additives can interact and modulate the humoral immunity of broilers, but not sufficiently to improve antibody titers against specific virus during a 42-day production cycle.
Mostrar más [+] Menos [-]Testing the role of external debt in environmental degradation: empirical evidence from Turkey Texto completo
2018
Katircioglu, Salih | Celebi, Aysem
This study investigates the role of external debt stock in Turkey, which has suffered from heavy (external and domestic) debt stock for many years. Annual data from 1960 to 2013 was analyzed using time series analysis in order to study this. The results confirm the validity of the conventional environmental Kuznets curve (EKC) in the case of Turkey. However, this study also found that Turkey’s external debt stock did not influence the Turkish economy’s long-term EKC behavior. Fortunately, the results suggest that there are important interactions among external debt stock, CO₂ emissions, energy consumption, and real income; that is, changes in external debt volume precede changes in these aggregates’ volumes.
Mostrar más [+] Menos [-]Heavy-metal speciation redistribution in solid phase and potential environmental risk assessment during the conversion of MSW incineration fly ash into molten slag Texto completo
2018
Luan, Jingde | Chai, Meiyun | Liu, Yawei | Ke, Xin
The alkalinity (AKₐₛₕ), BCR sequential extraction method, and principle component analysis (PCA) were adopted to investigate the heavy-metal partitioning and their speciation redistribution in solid phase in ash-melting process. The results indicated that the conversion of Zn-OXI (oxidisable fraction) into Zn-RES (residual fraction) and the decomposition of Cu-OXI fraction were prevailing in solid-phase reaction. Moreover, the alkalinity reduction from AKₐₛₕ = 2.0 to AKₐₛₕ = 1.2 had positive implications for the concentration reduction of As-RED (reducible fraction), Zn-RED, and Pb-RES fractions in slags. The modified synthesis toxicity index (STIM) calculation model was introduced to investigate the potential ecological risk (PEI) of heavy metals in the recycling and utilization of molten slag. Based on STIM calculation model, PEI of heavy metal in hazardous materials was classified into five ranks, such as serious pollution (STIM > 462), heavy pollution (330 < STIM < 462), moderate pollution (132 < STIM < 330), mild pollution (0 < STIM < 132), and no pollution (STIM = 0). The molten slags produced from fly ash can be directly reused as building materials like freestone and ceramics due to the mild PEI.
Mostrar más [+] Menos [-]Enhanced phosphorus removal using acid-treated magnesium slag particles Texto completo
2018
Tang, Xianqiang | Li, Rui | Wu, Min | Dong, Lei | Wang, Zhenhua
Magnesium-enriched magnesium slag particles (MSPs) can be used as an adsorption substrate as well as the magnesium source for struvite precipitation. In this study, an HCl treatment was used to enhance MSPs for phosphorus removal. After soaking in 1 mol/L HCl, an 11.27% decrease in median diameter (D50) and a 6.73% increase in specific surface area were observed when compared with the original MSPs. The improvement of the MSP surface properties resulted in 188.96 mg/kg increase in the PO₄³⁻ adsorption capacity. Irrespective of HCl treatment, the phosphorus adsorption process followed the Dubinin–Radushkevich (D–R) model much more accurately than the Langmuir and Freundlich equations with correlation coefficients higher than 0.94. The adsorption free energy obtained through the D–R model revealed a 9.75% decrease after HCl treatment. Sequential fraction extraction results indicated that 96% of the Mg²⁺ released from the HCl-treated MSPs came from acid-soluble magnesium (exchangeable and carbonate-bound). Mg²⁺ obtained from HCl-treated solutions provided a reliable magnesium source for struvite precipitation. The PO₄³⁻ removal rate can reach 53.63% with the optimal pH value of 10.0 and molar ratio of NH₄⁺ to PO₄³⁻ of 1:1. Struvite precipitation and adsorption can simultaneously occur in HCl-treated MSP solution. It contributed 63.19% to the overall PO₄³⁻ removal and is a major contributor compared with adsorption. Thus, HCl treatment greatly enhanced the potential of MSPs for phosphorus removal due to an improved adsorption capacity and is a reliable Mg²⁺ source for struvite precipitation.
Mostrar más [+] Menos [-]Human health risks of Hg, As, Mn, and Cr through consumption of fish, Ticto barb (Puntius ticto) from a tropical river, Bangladesh Texto completo
2018
Hossain, Mohammad Belal | Ahmed, Abu Sayeed Shafiuddin | Sarker, Md Shafiqul Islam
Metals tend to accumulate in higher organisms, e.g., fish and human through biomagnification effects in food chain. So, their presence in any component of the environment has become a global ecosystem and health concern. Here, we measured four health concerned metals like As, Cr, Mn, and Hg via inductively coupled plasma-mass spectrometry (ICP-MS) and analyzed applying some chemometrics for the assessment of human health risk through consumption of Puntius ticto, a very commonly consumed small fish in Bangladesh. The average concentration (wet weight) of metals was in the following descending order: Hg (0.006 mg/kg) > Cr (0.004 mg/kg) > Mn (0.003 mg/kg) > As (0.002 mg/kg). Hg level exceeded the provisional tolerable weekly intake (PTWI), and all other metals were within the permissible limit. The estimated daily intake (EDI) index of heavy metals showed that all the concentration levels were under the recommended daily intake (RDA) except Hg. Increased level of Hg is of particular concern to human health due to its biomagnification nature and can cause several neurological and physiological disorders including kidney failure. The total target hazard quotients (TTHQs) and carcinogenic risk (CR) matrices revealed that the intakes of Hg and As through fish consumption were higher than the recommended values, indicating consumers’ remain non-carcinogenic and carcinogenic (THQ > 1; CR > 10⁻⁵) health risks for lifetime consumption. Multivariate analyses (cluster and principal component) explained the sources of heavy metals in the study area originating from both anthropogenic and geological origin.
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