Synthesis of CdSe nanocrystals in a noncoordinating solvent: effect of reaction temperature on size and optical properties

Colloidal synthesis of high quality CdSe nanocrystals with controllable size and tunable properties have been one of the most important topics of research over the last decade, in view of its huge technological potentials. CdSe is one of the most studied nanocrystals of this category because of its photoluminescence tunability across the visible spectrum. We have synthesized CdSe nanocrystals using CdO precursor in a noncoordinating solvent and studied the effect of the reaction temperature on the size and optical properties of the nanocrystals. The size of the nanocrystals could be varied systematically in the range of 3.5 to 6.6 nm diameter with a remarkably narrow size distribution by controlling only the reaction temperature, without any need for a post-synthesis processing. The band gap and the corresponding band edge emission could be tuned across the entire visible range by tuning the size of the nanocrystals. The narrow width of the photoluminescence emissions of different colours (blue to red) make these nanocrystals a potential candidate for different optical and optoelectronic devices.

Distribution and possible source of trace elements in the sediment cores of a tropical macrotidal estuary and their ecotoxicological significance

The paper presents the first document regarding concentration, distribution and possible sources of selected trace elements (Cu, Fe, Mn, Zn, Cr, Co, Ni, Pb, Al, B and Ba) in core sediments (<63 micro particle size) from the lower stretch of Hugli (Ganges) estuary, northeast coast of Bay of Bengal by ICP-AES and EDXRF to evaluate geochemical processes influencing their distribution and possible environmental consequences. The levels of elements showed a wide range of variations in different core depths, in upper and lower intertidal zones as well as among three sampling stations. The most interesting feature of the study is the downward increase of concentrations of majority of the elements reaching overall maximum values at a depth of 20-28 cm in upper littoral zone of the site located in the extreme downstream stretch of the estuary. Values of organic carbon showed very strong positive correlations with most of the elements as revealed by correlation matrix (r) values. The interelemental relationship revealed the identical behavior of element during its transport in the estuarine environment. The overall variation in concentration can be attributed to differential discharge of untreated effluents originating from industrial, agricultural, and aquacultural sources as well as from domestic sewage along with the fishing and boating activities. The resulting compositional dataset was tested by principal component analyses and cluster analyses. Pollution load index (PLI) and index of Geoaccumulation (Igeo) revealed overall low values but the enrichment factors (EFs) for Pb were typically high for all the stations. The mean concentrations of Zn and to some extent Cu exceeded the Effects Range-Low (ER-L) values in the majority of the cases indicating that there may be some ecotoxicological risk to organisms living in sediments. The concentration of the trace elements reported in this work is useful as baselines for comparison in future sediment quality studies.

Preparation and preliminary biological evaluation of a novel 109Pd labeled porphyrin derivative for possible use in targeted tumor therapy

AIM

The labeling of a porphyrin, a tumor-avid agent, with a beta-emitting radionuclide for evaluating its potential as an agent for targeted tumor therapy is reported. A novel water soluble porphyrin viz. 5,10,15,20-tetrakis[3,4-bis(carboxymethyleneoxy)phenyl]porphyrin radiolabeled with(109)Pd (E(beta(max))=1.12 MeV, Eg=88 keV (3.6%), T1/2=13.7 h) has been prepared. The designing of this agent is based on the speculation that (109)Pd would complex with the tetrapyrrole donor array constituting the porphyrin core, resulting in a species with peripheral hydrophilic residues for facilitating renal excretion.

METHODS

Palladium-109 was produced by thermal neutron bombardment on enriched metallic Pd target at a flux of 3 x 10(13) n/cm(2) x s for 3 days and the porphyrin derivative was synthesized by a multi-step reaction using 3,4 dihydroxybenzaldehyde and pyrrole. The labeling parameters were optimized for obtaining maximum complexation yield and the biological behavior of the radiolabeled porphyrin was studied in Swiss mice bearing fibrosarcoma tumors.

RESULTS

Palladium-109 was produced with a specific activity of approximately 1.85 GBq/mg and approximately 100% radionuclidic purity. Lead-109 complex of the synthesized porphyrin derivative was prepared with excellent radiochemical purity (approximately 98%) and the complex was observed to be stable upto 24 h at room temperature. Results of the biodistribution studies revealed good tumor uptake (2.8+/-0.57%/g) within 30 min post-injection and it remained almost constant till 24 h post-injection. The complex showed predominantly renal clearance (88.68+/-4.01% at 24 h post-injection).

CONCLUSIONS

The high tumor/blood and tumor/muscle ratios (4.36 and 38 at 24 h post-injection) exhibited by the radiolabeled porphyrin indicate its potential for using in targeted tumor therapy.

White-light emission from a blend of CdSeS nanocrystals of different Se:S ratio

CdSeS nanocrystals with different bandgap energies have been synthesized by the colloidal method. The solution blend of blue-, green- and red-emitting CdSeS nanocrystals, in appropriate proportions, showed strong white emission of different shades on excitation with a UV source. We observed that the CIE coordinate of the spectrum of a particular blend is independent of excitation wavelength. We also observed that the contribution of self-absorption in energy loss in the blend of CdSeS nanocrystals is not very significant. A white-light-emitting LED has been fabricated by coating a blend mixed with polymethylmethacrylate on a commercial UV-LED.

Platelet activation, upregulation of CD11b/ CD18 expression on leukocytes and increase in circulating leukocyte-platelet aggregates in Indian women chronically exposed to biomass smoke

The majority of households in rural India still rely on unprocessed solid biomass for domestic energy. The aim of this study was to investigate whether chronic exposure to biomass smoke causes activation of leukocytes and the formation of leukocyte-platelet aggregates. We conducted flow cytometric analysis of beta2 Mac-1 integrin (CD11b/CD18) expression on polymorphonuclear leukocytes (PMN) and monocytes, and P-selectin (CD62P) expression on the platelets of 165 women from eastern India, who cook solely with wood, dung and agricultural wastes, and 155 age- and socio-economic condition-matched control subjects, who used relatively cleaner fuel, liquefied petroleum gas (LPG). Leukocyte-platelet aggregates were defined as CD11b-positive PMN and monocytes co-expressing platelet-specific markers CD41 or CD62P. A significant increase in leukocyte-platelet aggregates was found in women who used biomass as cooking fuel. In addition, they showed increased surface expression of CD11b/CD18 in circulating PMN and monocytes and CD62P expression on platelets. The mean fluorescence intensity (MFI) of CD11b on the surface of circulating monocytes and PMN of biomass users increased by 50 and 68%, respectively. Similarly, a 62 and 48% increase in MFI was observed in CD18 expression on the surface of these cells in biomass users. The results show that chronic biomass smoke exposure activates circulating platelets, PMN and monocytes, and increases the number of leukocyte-platelet aggregates, which are considered a risk factor for thrombosis.

A cohort study of correlation between body mass index and age at menarche in healthy Bengali girls

There are contradictory reports of lowering of age at menarche due to increasing body mass index (BMI) in the population. It is not known if a greater BMI at menarche is associated with a lower menarcheal age in healthy Bengali girls of normal nutrition. In this study the age at menarche was determined in 273 Bengali girls of middle income families. It was assessed whether BMI standard deviation scores (SDS) at menarche, BMI SDS at one year preceding menarche and BMI increments during that year were in correlation with age at menarche. The age of the girls with adequate nutrition was 8-16 years. They were examined for BMI, pubertal breast staging and age at menarche over a 4-year follow-up period. BMI SDS were calculated from National Center for Health Statistics (NCHS) normative data. The median age at menarche of 12.0 (range 10.0 - 16.0) years did not correlate with BMI SDS at menarche or BMI SDS at one year preceding menarche in this cohort. In univariate analysis, BMI increments for a given breast stage did not significantly lower the age at menarche. The change of BMI in the year preceding menarche did not correlate with age at menarche. The age at menarche in healthy Bengali girls of middle income families was similar to that of other Indian observations. There was no influence of BMI increments or that of BMI SDS prior to or at menarche on age at menarche.

The effect of 3BS locus of Sumai 3 on Fusarium head blight resistance in Australian wheats

The 3BS allele of Sumai 3 has been the main source of Fusarium head blight (FHB) resistance worldwide. Using molecular markers and FHB resistance screenings, we have analysed the effects of this allele in two backcross and two 4-way F2 populations derived from elite Australian cultivars. Compared to individuals without the Sumai 3 allele, individuals with the allele showed an average 32.0% reduction in FHB severity as measured by number of diseased spikelets. This value was slightly reduced to 29.2% when the total number of spikelets was taken into account by expressing severity as the proportion of diseased spikelets. When compared to the parental cultivars, progeny with the 3BS allele of Sumai 3 offered, on average, 43.3% reduction in FHB severity. Significant differences were not detected between progeny that were homozygous or heterozygous for the 3BS locus, indicating a dominant inheritance of this locus. These results confirm that the 3BS allele controls a large component of the FHB resistance in Sumai 3, which can be readily incorporated and detected in backcross populations using molecular markers. The materials derived from this study could offer significant benefits to the Australian wheat breeding programs.

Screening of wheat varieties and associated bacterial population in old alluvial soil of Burdwan, West Bengal

In order to screen out the best variety of wheat (Triticum aestivum) out of eight varieties (viz., HP 1633, BW 11, NW 1014, Sonalika, HUW 468, K 9107, HP 1731 and HUW 234), a field experiment was conducted (from Dec. 2002 to April 2003) in a randomized block design replicated thrice at Crop Research and Seed Multiplication Farm, Burdwan University, West Bengal, India. Various morpho physiological parameters viz., plant population, length of shoot and root, leaf area index (LAI), crop growth rate (CGR), leaf area ratio (LAR), leaf area duration (LAD), net assimilation rate (NAR), yield attributes viz., length of panicles, number of grains per panicle, grain yield, straw yield, pigment content in flag leaf (chlorophyll a, b and total chlorophyll and carotenoid content) were estimated and analyzed statistically Soil bacterial populations were also estimated in the fallow land before sowing of seeds and after harvesting of crop. The HUW 468 variety records higher grain yield, maximum panicle length and maximum chlorophyll b and total chlorophyll content.

Blue-Emitting Copper-Doped Zinc Oxide Nanocrystals

We report the first synthesis of Cu doped in the core region of ZnO nanocrystals and fluorescing in the blue region, establishing the novel possibility of using these as fluorescent probes.

Cloning, restriction mapping and phylogenetic relationship of genomic components of MYMIV from Lablab purpureus

The present work describes cloning of genomic components of whitefly transmitted geminivirus infecting Lablab purpureus syn. Dolichos lablab (commonly known as Dolichos bean or Hyacinth bean). The genome characterization using PCR with geminiviral degenerate primers and DNA sequencing were used to describe the bipartite virus associated with yellow mosaic disease of Dolichos lablab. Full-length DNA-A and DNA-B clones were obtained. The DNA-A sequence analysis showed that the isolate was similar to other Mungbean yellow mosaic India virus (MYMIV) isolates reported earlier. The nucleotide sequence analysis of the full-length DNA-A of virus isolate revealed more than 97% homology with Mungbean yellow mosaic India virus-[Cowpea] (AF481865), while the DNA-B also showed >95% homology with MYMIV-[Cp] (AF503580) and MYMIV-[Sb] (AY049771). The phylogenetic analysis of present isolate showed close relationship to legume geminiviruses. The nucleotide sequence analysis showed presence of six open reading frames (ORFs) in DNA-A, with 2 ORFs aligned in sense and 4 ORFs in antisense orientation. Similarly, DNA-B contained two open reading frames (ORFs), one in sense and another in antisense orientation.

Bilateral infraoptic origin of anterior cerebral arteries: a rare anomaly and its embryological and clinical significance

SUMMARY

We describe a case of bilateral infraoptic origin of the anterior cerebral arteries associated with an anterior communicating artery (ACOM) aneurysm. Anatomical variations of the anterior cerebral artery (ACA) are common; however, bilateral infraoptic course of the anterior cerebral artery is extremely rare. Since an infraoptic course of the ACA is associated with ACOM aneurysm formation, an understanding of the cerebrovascular anatomy and embryology is important for appropriate management of the aneurysm.

Arsenic trioxide for treatment of myelodysplastic syndrome: An experience from India

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Background: Myelodysplastic Syndrome (MDS) is a heterogeneous group of clonal diseases of the haematopoietic stem cells. The hallmark of the disease is ineffective haematopoiesis characterized by dysplasia with incomplete maturation and progressive increase in the percentage of myeloblast. No standard treatment is currently available for MDS. The early clinical experience has confirmed the activity of arsenic trioxide in MDS. The drug is able to induce differentiation and apoptosis and to inhibit cell proliferation or angiogenesis. It has the potential to be active in tumour models in MDS. The preliminary result of ongoing studies conducted in patients with MDS suggests that arsenic trioxide produces haematological improvement including durable transfusion independence in 30% of patients. The aim of our study was to see the response of MDS with arsenic trioxide and to see the toxicity profile of arsenic trioxide in Asian Indian population. Methods: During period from July 2005 to December 2005 we selected consecutive 10 patients of MDS in Refractory Anaemia, Refractory anaemia with ringed sideroblasts, Refractory anaemia with blast excess, Refractory anaemia with blast excess in transformations and chronic myelo monocytic leukemia phases. All patients had performance status more than 60%, some karyotypic abnormalities & in cytopenic phase. Median age of the patients 65 years (range 42 to 70 years). All patients were treated with arsenic trioxide 10mg (Alkem/India) daily for 2 hours infusion 28 days. In 15 days interval 3 courses were repeated. Response assessments were done by haematological, cytogenetic & quality of life assessment. All patients were evaluated after 3 courses of arsenic trioxide. Result: Sixty percent (6 patients) patients had shown major haematological response, forty percent minor & twenty percent has major cytogenetic response. Twenty percent of the patients has disease progression where as 20% has stable disease. The only mild adverse effects were seen in forms of nausea, vomiting, diarrhea, abdominal pain & dermatitis in 30% of patients. Only one patient (10%) had QT prolongation in ECG. Conclusion: We concluded that arsenic trioxide is very useful drug in myelodysplastic syndrome. It is also well tolerated in Asian Indian Population.

No significant financial relationships to disclose.

Residues of DDT and HCH in wheat samples collected from different states of India and their dietary exposure: A multicentre study

Under a multicentre study conducted by the Indian Council of Medical Research, 1712 samples of wheat grain/flour were collected from urban and rural areas in 11 states representing different geographical regions of India. These samples were analysed for residues of DDT (2,2-bis (p-chlorophenyl)-1,1,1-trichloro ethane) and different isomers of HCH (1,2,3,4,5,6-hexachloro cyclohexane, a mixture of isomers) by gas-liquid chromatography. Residues of DDT were detected in 59.4% of 1080 samples of wheat grain and in 78.2% of 632 samples of wheat flour. Different isomers of HCH were present in about 45-80% of the samples of wheat grain/flour. Medians of DDT and total HCH, respectively, for pooled samples of wheat grain were 0.013 and 0.035 mg kg(-1), while those for wheat flour were 0.01 and 0.02 mg kg(-1). Estimated daily intakes of DDT and different isomers of HCH through the consumption of wheat contaminated at their median and 90th percentiles constituted a small proportion of their acceptable daily intakes. Amongst the pesticide residues analysed, statutory maximum residue limits have been fixed only for gamma-HCH in wheat in India, as 0.1 mg kg(-1) in wheat grain and zero in wheat flour. Residue levels of gamma-HCH exceeded these maximum residue limits in five of 1080 samples of wheat grain and in 340 of 632 samples of wheat flour. The failure to meet the requirement of the gamma-HCH maximum residue limit in large number of wheat flour samples was attributed to the fixation of practically unachievable zero limit. Comparing the previous studies and the present one, the levels of residues of DDT and HCH in wheat were significantly decreased.

Effect of vermicomposting process on metal content of paper mill solid waste

In the present study the change in metal content on vermicomposting of paper mill solid waste was studied. On vermicomposting, quantity of iron, zinc and chromium found to be increased whereas quantity of aluminium, copper, manganese, nickel and lead found comparatively low. The bioaccumulation of any metal was not observed in the body of the earthworm, hence after vermicomposting, there is no harm to fishes to utilize earthworm biomass as their food. The metal content in the vermicompost prepared from the paper mill solid waste was well within the permissive limits and can therefore be safely applied in an aquaculture, agriculture and other food production systems.