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CHARACTERIZATION AND IDENTIFICATION OF THE SOURCES OF CHROMIUM, ZINC, LEAD, CADMIUM, NICKEL, MANGANESE AND IRON IN PM10 PARTICULATES AT THE TWO SITES OF KOLKATA, INDIA
No full textMonitoring of ambient PM10 (particulate matter which passes through a size selective impactor inlet with a 50% efficiency cut-off at 10μm aerodynamic diameter) has been done at residential (Kasba) and industrial (Cossipore) sites of an urban region of Kolkata during November 2003
to November 2004. These sites were selected depending on the dominant anthropogenic activities.Metal constituents of atmospheric PM10 deposited on glass fibre filter paper were estimated using Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). Chromium (Cr), zinc (Zn),lead (Pb), cadmium (Cd), nickel (Ni), manganese (Mn) and iron (Fe) are the seven toxic trace metals quantified from the measured PM10 concentrations. The 24 h average concentrations of Cr, Zn, Pb,Cd, Ni, Mn and Fe from ninety PM10 particulate samples of Kolkata were found to be 6.9, 506.1,79.1, 3.3, 7.4, 2.4 and 103.6 ng/m3, respectively. The 24 h average PM10 concentration exceeded national ambient air quality standard (NAAQS) as specified by central pollution control board, India at both residential (Kasba) and industrial (Cossipore) areas with mean concentration of 140.1 and
196.6μg/m3, respectively. A simultaneous meteorology study was performed to assess the influence of air masses by wind speed, wind direction, rainfall, relative humidity and temperature. The measured toxic trace metals generally showed inverse relationship with wind speed, relative humidity and temperature. Factor analysis, a receptor modeling technique has been used for identification of the
possible sources contributing to the PM10. Varimax rotated factor analysis identified four possible sources of measured trace metals comprising solid waste dumping, vehicular traffic with the influence of road dust, road dust and soil dust at residential site (Kasba), while vehicular traffic with the influence of soil dust, road dust, galvanizing and electroplating industry, and tanning industry at industrial site (Cossipore)
Simultaneous degradation of non-emissive and emissive dyes on Visible light illuminated TiO2 surface
Get PDFSimultaneous photocatalytic degradation of non-emissive dye, acid blue1 (AB1) and emissive dyes (eosinY or thionine) in air-equilibrated aqueous suspension of TiO2 semiconductor photocatalyst has been achieved at ambient conditions. Under visible light irradiation AB1 undergoes
appreciable degradation in presence of a sensitizing dye (eosinY or thionine). However, concomitant decoloration of eosinY (EY) or thionine (Th)due to self-sensitized degradation was also noticed. Mechanistic proposals for the photocatalytic degradation of AB1 using a 150WXe lamp with
a UV-filter (λ > 420 nm) as well as without a UV-filter, are discussed. Formation of reactive •O2−/•HO2 radicals is proposed to be responsible for the degradation of the selected dyes, AB1, EY and Th
Oncogene-Blocking Therapies: New Insights from Conditional Mouse Tumor Models
No full textIdentification of oncogene dependent signaling pathways controlling aggressive tumor growth has led to the emergence of a new era of oncogene-blocking therapies, including Herceptin and Gleevec. In the recent years conditional mouse tumor models have been established that allow switching-off the expression of specific oncogenes controlling tumor growth. The results may have two important implications for oncogeneblocking therapies: (i) downregulation of oncogenes, for instance HER2, MYC, RAS, RAF, BCR-ABL or WNT1,usually leads to a rapid tumor remission. However, it was observed that the initial remission was followed by recurrent tumor growth in most studies. Interestingly, different oncogenes controlled tumor growth in the recurrent than in the primary tumors. This could explain the astonishing clinical observation that inhibitors of a broader spectrum of protein kinases (so-called: “dirty inhibitors”) may be superior over highly specific substances. Due to their additional “unspecific” inhibition of a broader spectrum of kinases, they may hamper
the escape mechanisms by antagonizing also the pathways controlling recurrent tumor growth. (ii) Experiments with cell systems that allow switching-on oncogene expression point to a so far possibly underestimated cancer drug target: the dormant tumor cell. Oncogene expression (for instance: NeuT or RAS) led to a phenomenon named oncogene-induced senescence or dormancy. Dormant cells are unresponsive to mitogenic stimuli. Importantly, such cells are not at all ready to die, but can remain viable for extended periods of time.Recently, dormant tumor cells have been shown to be more resistant to stresses such as hypoxia or exposure to cytostatic drugs. It still is a matter of debate if and under which conditions dormant tumor cells can be “kissed to life”. If these cells contribute to carcinogenesis, it will be important to identify substances specifically killing senescent cells. This review will focus on the possible relevance of senescence both as a pre-oncogenic condition and also for therapy
UNDERSTANDING URBAN VEHICULAR POLLUTION PROBLEM VIS-A-VIS AMBIENT AIR QUALITY – CASE STUDY OF A MEGACITY (DELHI, INDIA)
No full textAir pollution has become a growing problem in megacities and large urban areas through
out the globe, and transportation is recognized as the major source of air pollution in many cities,
especially in developing countries. Contribution of automobiles is reported in the range of 40 to 80%
of the total air pollution. The challenge facing megacities is how to reduce the adverse environmental
impacts and other negative effects of transportation without giving up the benefits of mobility. The
dilemma becomes most pressing under conditions of rapid urban growth, which is likely to increase
travel demand significantly.
The paper is aimed at understanding the problem of vehicular pollution vis-a-vis ambient air
quality for a highly traffic affected megacity, Delhi, wherein, the contribution of transport sector was
estimated to be as high as 72%. An effort has been made to review and evaluate the benefits (in terms
of improved air quality) of the technological interventions/policies adopted for vehicular pollution
control in Delhi. It also highlights the outcome of the efforts and suggests further improvements
thereon. The importance of public participation and awareness are also discussed. The paper focuses
on deriving the benefits of the implementation of management strategies, supported by scientific
and technical data/ interpretation, so that the people can realize and participate in the government’s
endeavor for clean city drive in a more effective manner
Statistical analysis of counts and spacing of consistent repeating patterns in a set of homologous DNA sequences
No full textUnusual patterns in nucleic acid or protein sequences are often suspected for their biological relevance. Repeating patterns of nucleotides are one such type and are typically searched in large genome sequences. In this exercise, our interest is to look for repeating patterns, which are conserved in a set of homologous DNA sequences, not only in terms of their counts/occurrences,but also their spacing/seperating distances. We refer to such patterns as consistent repeating patterns. It becomes desirable to know the probability of multiple occurence of pattern in sequences and whether the spacing due to occurrences of pattern in the sequence exhibits any statistically significant property. The information derived through statistical analysis may help in planning experiments or even raise new queries that may require attention to better understand the molecular mechanisms. A case study with four hundred 16S rDNA sequences resulted into nine most consistent repeaing patterns. The statistical significance of counts of these patterns was studied using Poisson approximation. The spacing analysis of patterns was carried with recourse to uniform probability distribution. The analysis revealed that most of the patterns show significant clustering, with one pattern occuring thrice and evenly dispersed in a sequence. The significance of occurrence and spacing of repeating patterns raised a few queries explanation, perhaps through experimentation
Inter-Laboratory Comparision of NO2 and So2 Generated by Dynamic Dilution System Under Laboratory Contitions:A Technical Discussion.
No full textA workshop on analytical quality control (AQC) of ambient air quality measurement
methods for nitrogen dioxide (NO2) and sulphur dioxide (SO2) was conducted by Central Pollution
Control Board (CPCB) for officials involved in National Ambient Air Quality Monitoring (NAAQM)
in India. Concentrations of NO2 and SO2 were generated by dynamic dilution system under laboratory
conditions at low and high levels and measured using static dilution system and wet chemical methods
laid down by CPCB under section 16(2)(h) of the air act 1981. CPCB provided the measured values
as reference values for comparing the means obtained by the officials participated from thirteen
organizations. A tolerance limit of ±15% of the reference values was specified to accept the results.
Generated concentrations, which were unknown to the participants, were measured using gaseous
sampling assembly (Envirotech APM 411, New Delhi, India), and wet chemical methods laid down
by CPCB i.e. the same methodology which is used by the organizations to generate the data of NO2 and
SO2 in ambient air. Simultaneously, concentrations were checked by CPCB using automatic analyzers
as a check on reference concentration. It is observed that results of automatic analyzers for NO2 and
SO2 were within a tolerance of ±5% with %RSD below 3. On the other hand, results of most of the
participants showed variability in the measurements with %RSD ranging between ±0.8 and ±88.6
and exceedences of means from the tolerance limit with bias ranging between 1.4 and −59%. To
check the cause of high variability in the measurements obtained under identical conditions, duplicate
sampling was performed by one of the participants for SO2 at low concentration level. In this study,
results of wet chemical methods, automatic analyzers and results of duplicate sampling are analysed
statistically to assess the cause of high variability in the measurements. Analysis of t-test and analysis
of variance (ANOVA) showed highly significant results for NO2 and SO2 at high concentration levels
(α 0.05) and for SO2 at both the levels (α 0.01) respectively indicating some bias is existing either in
the sampling or in analytical technique. Duplicate sampling performed to check precision in parallel
measurements showed high %RSD indicating the presence of systematic error in sampling technique
as the same calibration factor (CF) was used to measure the concentration of duplicate samples.
Statistical analysis of flow rates of duplicate sampling showed that the sampling assembly could not
maintain the constant flow rate within the ±10% with that measured at the start of the sampling.
This resulted in high %RSD and deviation from the reference values for the results of most of the
participants, even after accepting ±15% tolerance limit. There is a need to improve and evaluate this
gaseous sample collection device under laboratory conditions to generate reliable database of NO2
and SO2 in ambient air
Biodegradation of tech-hexachlorocyclohexane in a upflow anaerobic sludge blanket (UASB) reactor
No full textBiodegradability of technical grade hexachlorocyclohexane (tech-HCH) was studied in an upflow anaerobic sludge blanket reactor (UASB) under continuous mode of operation in concentration range of 100–200 mg/l and constant HRT of 48 h. At steady state operation more than 85% removal of tech-HCH (upto 175 mg/l concentration) and complete disappearance of b-HCH was observed. Kinetic constants in terms of maximum specific tech-HCH utilization rate (k) and half saturation velocity constant (KL) were found to be 11.88 mg/g/day and 8.11 mg/g/day, respectively. The tech-HCH degrading seed preparation, UASB reactor startup and degradation in continuous mode of operation of the reactor is presented in this paper
Photocatalytic properties of zeolite-based materials for the photoreduction of methyl orange
No full textNovel photocatalytic materials have been prepared by incorporation of TiO2, a transition metal and, heteropolyacid (HPA) in the zeolite structure. These materials have been characterized using XRD, UV–vis diffuse reflectance spectroscopy and elemental analysis. The photocatalytic activity of the materials in visible light has been evaluated for photoreduction of methyl orange solution in the presence of a sacrificial electron donor 1:40 ethanol–water mixture. The material Zeo-/TiO2/Co2+/HPA photoreduces methyl orange effectively to the extent of about 4.11 mg/g TiO2 and shows better photocatalytic activity as compared to Zeo-Y/TiO2/HPA, indicating the role of transition metal ions. The improved photocatalytic properties in the visible region could be due to the combined effect of transition metal ions and HPA, while these constituents along with the zeolite framework are also likely to contribute towards delay in charge recombination
Physico-chemical and surface characterization of adsorbent prepared from groundnut shell by ZnCl2 activation and its ability to adsorb colour.
No full textMethods for determining microcystins (peptide hepatotoxins) and microcystin-producing cyanobacteria
No full textEpisodes of cyanobacterial toxic blooms and fatalities to animals and humans due to cyanobacterial toxins (CBT) are known worldwide. The hepatotoxins and neurotoxins
(cyanotoxins) produced by bloom-forming cyanobacteria have been the cause of human and animal health hazards and even death. Prevailing concentration of cell bound endotoxin, exotoxin and the toxin variants depend on developmental stages of the bloom and the cyanobacterial (CB) species involved. Toxic and non-toxic strains do not show any predictable morphological difference. The current instrumental, immunological and molecular methods applied for determining microcystins (peptide hepatotoxins) and microcystin-producing cyanobacteria are reviewed